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diff --git a/old/dscmn11.txt b/old/dscmn11.txt new file mode 100644 index 0000000..0c408f0 --- /dev/null +++ b/old/dscmn11.txt @@ -0,0 +1,33436 @@ +The Project Gutenberg Etext The Descent of Man by Charles Darwin + +Copyright laws are changing all over the world, be sure to check +the copyright laws for your country before posting these files!! + +Please take a look at the important information in this header. +We encourage you to keep this file on your own disk, keeping an +electronic path open for the next readers. Do not remove this. + + +**Welcome To The World of Free Plain Vanilla Electronic Texts** + +**Etexts Readable By Both Humans and By Computers, Since 1971** + +*These Etexts Prepared By Hundreds of Volunteers and Donations* + +Information on contacting Project Gutenberg to get Etexts, and +further information is included below. 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Portraits. 3 volumes 36s. Popular Edition. +Condensed in 1 volume 7s 6d. + +Naturalist's Journal of Researches into the Natural History and Geology of +Countries Visited during a Voyage Round the World. With 100 Illustrations +by Pritchett. 21s. Popular Edition. Woodcuts. 3s 6d. Cheaper Edition, +2s. 6d. net. + +Origin of Species by means of Natural Selection; or, The Preservation of +Favoured Races in the Struggle for Life. Large Type Edition, 2 volumes +12s. Popular Edition, 6s. Cheaper Edition with Portrait, 2s. 6d. + +Various Contrivances by which Orchids are Fertilized by Insects. Woodcuts. +7s. 6d. + +Variation of Animals and Plants under Domestication. Illustrations. 15s. + +Descent of Man, and Selection in relation to Sex. Illustrations. Large +Type Edition, 2 volumes 15s. Popular Edition, 7s 6d. Cheaper Edition, 2s. +6d. net. + +Expression of the Emotions in Man and Animals. Illustrations. 12s. + +Insectivorous Plants. Illustrations. 9s. + +Movements and Habits of Climbing Plants. Woodcuts. 6s. + +Cross and Self-Fertilization in the Vegetable Kingdom. Illustrations. 9s. + +Different Forms of Flowers on Plants of the Same Species. Illustrations. +7s. 6d. + +Formation of Vegetable Mould through the Action of Worms. Woodcuts. 6s. + +The above works are Published by John Murray. + +Structure and Distribution of Coral Reefs. Smith, Elder, & Co. + +Geological Observations on Volcanic Islands and Parts of South America. +Smith, Elder, & Co. + +Monograph of the Cirripedia. Illustrations. 2 volumes. 8vo. Ray +Society. + +Monograph of the Fossil Lepadidae, or Pedunculated Cirripedes of Great +Britain. Palaeontographical Society. + +Monograph of the Fossil Balanidae and Verrucidae of Great Britain. +Palaeontographical Society. + + + + +THE DESCENT OF MAN + +AND + +SELECTION IN RELATION TO SEX + +BY + +CHARLES DARWIN, M.A., F.R.S. + + +Uniform with this Volume + +The Origin of Species, by means of Natural Selection; or, The Preservation +of Favoured Races in the Struggle for Life. Popular Edition, with a +Photogravure Portrait. Large Crown 8vo. 2s. 6d. net. + +A Naturalist's Voyage. Journal of Researches into the Natural History and +Geology of the Countries visited during the Voyage of H.M.S. "Beagle" round +the World, under the Command of Capt. Fitz Roy, R.N. Popular Edition, with +many Illustrations. Large Crown 8vo. 2s. 6d. net. + + +PREFACE TO THE SECOND EDITION. + +During the successive reprints of the first edition of this work, published +in 1871, I was able to introduce several important corrections; and now +that more time has elapsed, I have endeavoured to profit by the fiery +ordeal through which the book has passed, and have taken advantage of all +the criticisms which seem to me sound. I am also greatly indebted to a +large number of correspondents for the communication of a surprising number +of new facts and remarks. These have been so numerous, that I have been +able to use only the more important ones; and of these, as well as of the +more important corrections, I will append a list. Some new illustrations +have been introduced, and four of the old drawings have been replaced by +better ones, done from life by Mr. T.W. Wood. I must especially call +attention to some observations which I owe to the kindness of Prof. Huxley +(given as a supplement at the end of Part I.), on the nature of the +differences between the brains of man and the higher apes. I have been +particularly glad to give these observations, because during the last few +years several memoirs on the subject have appeared on the Continent, and +their importance has been, in some cases, greatly exaggerated by popular +writers. + +I may take this opportunity of remarking that my critics frequently assume +that I attribute all changes of corporeal structure and mental power +exclusively to the natural selection of such variations as are often called +spontaneous; whereas, even in the first edition of the 'Origin of Species,' +I distinctly stated that great weight must be attributed to the inherited +effects of use and disuse, with respect both to the body and mind. I also +attributed some amount of modification to the direct and prolonged action +of changed conditions of life. Some allowance, too, must be made for +occasional reversions of structure; nor must we forget what I have called +"correlated" growth, meaning, thereby, that various parts of the +organisation are in some unknown manner so connected, that when one part +varies, so do others; and if variations in the one are accumulated by +selection, other parts will be modified. Again, it has been said by +several critics, that when I found that many details of structure in man +could not be explained through natural selection, I invented sexual +selection; I gave, however, a tolerably clear sketch of this principle in +the first edition of the 'Origin of Species,' and I there stated that it +was applicable to man. This subject of sexual selection has been treated +at full length in the present work, simply because an opportunity was here +first afforded me. I have been struck with the likeness of many of the +half-favourable criticisms on sexual selection, with those which appeared +at first on natural selection; such as, that it would explain some few +details, but certainly was not applicable to the extent to which I have +employed it. My conviction of the power of sexual selection remains +unshaken; but it is probable, or almost certain, that several of my +conclusions will hereafter be found erroneous; this can hardly fail to be +the case in the first treatment of a subject. When naturalists have become +familiar with the idea of sexual selection, it will, as I believe, be much +more largely accepted; and it has already been fully and favourably +received by several capable judges. + +DOWN, BECKENHAM, KENT, +September, 1874. + +First Edition February 24, 1871. +Second Edition September, 1874. + + +CONTENTS. + + +INTRODUCTION. + + +PART I. THE DESCENT OR ORIGIN OF MAN. + + +CHAPTER I. + +The Evidence of the Descent of Man from some Lower Form. + +Nature of the evidence bearing on the origin of man--Homologous structures +in man and the lower animals--Miscellaneous points of correspondence-- +Development--Rudimentary structures, muscles, sense-organs, hair, bones, +reproductive organs, etc.--The bearing of these three great classes of +facts on the origin of man. + + +CHAPTER II. + +On the Manner of Development of Man from some Lower Form. + +Variability of body and mind in man--Inheritance--Causes of variability-- +Laws of variation the same in man as in the lower animals--Direct action of +the conditions of life--Effects of the increased use and disuse of parts-- +Arrested development--Reversion--Correlated variation--Rate of increase-- +Checks to increase--Natural selection--Man the most dominant animal in the +world--Importance of his corporeal structure--The causes which have led to +his becoming erect--Consequent changes of structure--Decrease in size of +the canine teeth--Increased size and altered shape of the skull--Nakedness +--Absence of a tail--Defenceless condition of man. + + +CHAPTER III. + +Comparison of the Mental Powers of Man and the Lower Animals. + +The difference in mental power between the highest ape and the lowest +savage, immense--Certain instincts in common--The emotions--Curiosity-- +Imitation--Attention--Memory--Imagination--Reason--Progressive improvement +--Tools and weapons used by animals--Abstraction, Self-consciousness-- +Language--Sense of beauty--Belief in God, spiritual agencies, +superstitions. + + +CHAPTER IV. + +Comparison of the Mental Powers of Man and the Lower Animals--continued. + +The moral sense--Fundamental proposition--The qualities of social animals-- +Origin of sociability--Struggle between opposed instincts--Man a social +animal--The more enduring social instincts conquer other less persistent +instincts--The social virtues alone regarded by savages--The self-regarding +virtues acquired at a later stage of development--The importance of the +judgment of the members of the same community on conduct--Transmission of +moral tendencies--Summary. + + +CHAPTER V. + +On the Development of the Intellectual and Moral Faculties during Primeval +and Civilised times. + +Advancement of the intellectual powers through natural selection-- +Importance of imitation--Social and moral faculties--Their development +within the limits of the same tribe--Natural selection as affecting +civilised nations--Evidence that civilised nations were once barbarous. + + +CHAPTER VI. + +On the Affinities and Genealogy of Man. + +Position of man in the animal series--The natural system genealogical-- +Adaptive characters of slight value--Various small points of resemblance +between man and the Quadrumana--Rank of man in the natural system-- +Birthplace and antiquity of man--Absence of fossil connecting-links--Lower +stages in the genealogy of man, as inferred firstly from his affinities and +secondly from his structure--Early androgynous condition of the Vertebrata +--Conclusion. + + +CHAPTER VII. + +On the Races of Man. + +The nature and value of specific characters--Application to the races of +man--Arguments in favour of, and opposed to, ranking the so-called races of +man as distinct species--Sub-species--Monogenists and polygenists-- +Convergence of character--Numerous points of resemblance in body and mind +between the most distinct races of man--The state of man when he first +spread over the earth--Each race not descended from a single pair--The +extinction of races--The formation of races--The effects of crossing-- +Slight influence of the direct action of the conditions of life--Slight or +no influence of natural selection--Sexual selection. + + +PART II. SEXUAL SELECTION. + + +CHAPTER VIII. + +Principles of Sexual Selection. + +Secondary sexual characters--Sexual selection--Manner of action--Excess of +males--Polygamy--The male alone generally modified through sexual +selection--Eagerness of the male--Variability of the male--Choice exerted +by the female--Sexual compared with natural selection--Inheritance at +corresponding periods of life, at corresponding seasons of the year, and as +limited by sex--Relations between the several forms of inheritance--Causes +why one sex and the young are not modified through sexual selection-- +Supplement on the proportional numbers of the two sexes throughout the +animal kingdom-- The proportion of the sexes in relation to natural +selection. + + +CHAPTER IX. + +Secondary Sexual Characters in the Lower Classes of the Animal Kingdom. + +These characters are absent in the lowest classes--Brilliant colours-- +Mollusca--Annelids--Crustacea, secondary sexual characters strongly +developed; dimorphism; colour; characters not acquired before maturity-- +Spiders, sexual colours of; stridulation by the males--Myriapoda. + + +CHAPTER X. + +Secondary Sexual Characters of Insects. + +Diversified structures possessed by the males for seizing the females-- +Differences between the sexes, of which the meaning is not understood-- +Difference in size between the sexes--Thysanura--Diptera--Hemiptera-- +Homoptera, musical powers possessed by the males alone--Orthoptera, musical +instruments of the males, much diversified in structure; pugnacity; +colours--Neuroptera, sexual differences in colour--Hymenoptera, pugnacity +and odours--Coleoptera, colours; furnished with great horns, apparently as +an ornament; battles; stridulating organs generally common to both sexes. + + +CHAPTER XI. + +Insects, continued.--Order Lepidoptera. + +(Butterflies and Moths.) + +Courtship of Butterflies--Battles--Ticking noise--Colours common to both +sexes, or more brilliant in the males--Examples--Not due to the direct +action of the conditions of life--Colours adapted for protection--Colours +of moths--Display--Perceptive powers of the Lepidoptera--Variability-- +Causes of the difference in colour between the males and females--Mimicry, +female butterflies more brilliantly coloured than the males--Bright colours +of caterpillars--Summary and concluding remarks on the secondary sexual +character of insects--Birds and insects compared. + + +CHAPTER XII. + +Secondary Sexual Characters of Fishes, Amphibians, and Reptiles. + +Fishes: Courtship and battles of the males--Larger size of the females-- +Males, bright colours and ornamental appendages; other strange characters-- +Colours and appendages acquired by the males during the breeding-season +alone--Fishes with both sexes brilliantly coloured--Protective colours--The +less conspicuous colours of the female cannot be accounted for on the +principle of protection--Male fishes building nests, and taking charge of +the ova and young. AMPHIBIANS: Differences in structure and colour +between the sexes--Vocal organs. REPTILES: Chelonians--Crocodiles-- +Snakes, colours in some cases protective--Lizards, battles of--Ornamental +appendages--Strange differences in structure between the sexes--Colours-- +Sexual differences almost as great as with birds. + + +CHAPTER XIII. + +Secondary Sexual Characters of Birds. + +Sexual differences--Law of battle--Special weapons--Vocal organs-- +Instrumental music--Love-antics and dances--Decorations, permanent and +seasonal--Double and single annual moults--Display of ornaments by the +males. + + +CHAPTER XIV. + +Birds--continued. + +Choice exerted by the female--Length of courtship--Unpaired birds--Mental +qualities and taste for the beautiful--Preference or antipathy shewn by the +female for particular males--Variability of birds--Variations sometimes +abrupt--Laws of variation--Formation of ocelli--Gradations of character-- +Case of Peacock, Argus pheasant, and Urosticte. + + +CHAPTER XV. + +Birds--continued. + +Discussion as to why the males alone of some species, and both sexes of +others are brightly coloured--On sexually-limited inheritance, as applied +to various structures and to brightly-coloured plumage--Nidification in +relation to colour--Loss of nuptial plumage during the winter. + + +CHAPTER XVI. + +Birds--concluded. + +The immature plumage in relation to the character of the plumage in both +sexes when adult--Six classes of cases--Sexual differences between the +males of closely-allied or representative species--The female assuming the +characters of the male--Plumage of the young in relation to the summer and +winter plumage of the adults--On the increase of beauty in the birds of the +world--Protective colouring--Conspicuously coloured birds--Novelty +appreciated--Summary of the four chapters on birds. + + +CHAPTER XVII. + +Secondary Sexual Characters of Mammals. + +The law of battle--Special weapons, confined to the males--Cause of absence +of weapons in the female--Weapons common to both sexes, yet primarily +acquired by the male--Other uses of such weapons--Their high importance-- +Greater size of the male--Means of defence--On the preference shewn by +either sex in the pairing of quadrupeds. + + +CHAPTER XVIII. + +Secondary Sexual Characters of Mammals--continued. + +Voice--Remarkable sexual peculiarities in seals--Odour--Development of the +hair--Colour of the hair and skin--Anomalous case of the female being more +ornamented than the male--Colour and ornaments due to sexual selection-- +Colour acquired for the sake of protection--Colour, though common to both +sexes, often due to sexual selection--On the disappearance of spots and +stripes in adult quadrupeds--On the colours and ornaments of the +Quadrumana--Summary. + + +PART III. SEXUAL SELECTION IN RELATION TO MAN, AND CONCLUSION. + + +CHAPTER XIX. + +Secondary Sexual Characters of Man. + +Differences between man and woman--Causes of such differences, and of +certain characters common to both sexes--Law of battle--Differences in +mental powers, and voice--On the influence of beauty in determining the +marriages of mankind--Attention paid by savages to ornaments--Their ideas +of beauty in women--The tendency to exaggerate each natural peculiarity. + + +CHAPTER XX. + +Secondary Sexual Characters of Man--continued. + +On the effects of the continued selection of women according to a different +standard of beauty in each race--On the causes which interfere with sexual +selection in civilised and savage nations--Conditions favourable to sexual +selection during primeval times--On the manner of action of sexual +selection with mankind--On the women in savage tribes having some power to +choose their husbands--Absence of hair on the body, and development of the +beard--Colour of the skin--Summary. + + +CHAPTER XXI. + +General Summary and Conclusion. + +Main conclusion that man is descended from some lower form--Manner of +development--Genealogy of man--Intellectual and moral faculties--Sexual +selection--Concluding remarks. + + +SUPPLEMENTAL NOTE. + + +INDEX. + + + +THE DESCENT OF MAN; AND SELECTION IN RELATION TO SEX. + +... + +INTRODUCTION. + +The nature of the following work will be best understood by a brief account +of how it came to be written. During many years I collected notes on the +origin or descent of man, without any intention of publishing on the +subject, but rather with the determination not to publish, as I thought +that I should thus only add to the prejudices against my views. It seemed +to me sufficient to indicate, in the first edition of my 'Origin of +Species,' that by this work "light would be thrown on the origin of man and +his history;" and this implies that man must be included with other organic +beings in any general conclusion respecting his manner of appearance on +this earth. Now the case wears a wholly different aspect. When a +naturalist like Carl Vogt ventures to say in his address as President of +the National Institution of Geneva (1869), "personne, en Europe au moins, +n'ose plus soutenir la creation indépendante et de toutes pièces, des +espèces," it is manifest that at least a large number of naturalists must +admit that species are the modified descendants of other species; and this +especially holds good with the younger and rising naturalists. The greater +number accept the agency of natural selection; though some urge, whether +with justice the future must decide, that I have greatly overrated its +importance. Of the older and honoured chiefs in natural science, many +unfortunately are still opposed to evolution in every form. + +In consequence of the views now adopted by most naturalists, and which will +ultimately, as in every other case, be followed by others who are not +scientific, I have been led to put together my notes, so as to see how far +the general conclusions arrived at in my former works were applicable to +man. This seemed all the more desirable, as I had never deliberately +applied these views to a species taken singly. When we confine our +attention to any one form, we are deprived of the weighty arguments derived +from the nature of the affinities which connect together whole groups of +organisms--their geographical distribution in past and present times, and +their geological succession. The homological structure, embryological +development, and rudimentary organs of a species remain to be considered, +whether it be man or any other animal, to which our attention may be +directed; but these great classes of facts afford, as it appears to me, +ample and conclusive evidence in favour of the principle of gradual +evolution. The strong support derived from the other arguments should, +however, always be kept before the mind. + +The sole object of this work is to consider, firstly, whether man, like +every other species, is descended from some pre-existing form; secondly, +the manner of his development; and thirdly, the value of the differences +between the so-called races of man. As I shall confine myself to these +points, it will not be necessary to describe in detail the differences +between the several races--an enormous subject which has been fully +described in many valuable works. The high antiquity of man has recently +been demonstrated by the labours of a host of eminent men, beginning with +M. Boucher de Perthes; and this is the indispensable basis for +understanding his origin. I shall, therefore, take this conclusion for +granted, and may refer my readers to the admirable treatises of Sir Charles +Lyell, Sir John Lubbock, and others. Nor shall I have occasion to do more +than to allude to the amount of difference between man and the +anthropomorphous apes; for Prof. Huxley, in the opinion of most competent +judges, has conclusively shewn that in every visible character man differs +less from the higher apes, than these do from the lower members of the same +order of Primates. + +This work contains hardly any original facts in regard to man; but as the +conclusions at which I arrived, after drawing up a rough draft, appeared to +me interesting, I thought that they might interest others. It has often +and confidently been asserted, that man's origin can never be known: but +ignorance more frequently begets confidence than does knowledge: it is +those who know little, and not those who know much, who so positively +assert that this or that problem will never be solved by science. The +conclusion that man is the co-descendant with other species of some +ancient, lower, and extinct form, is not in any degree new. Lamarck long +ago came to this conclusion, which has lately been maintained by several +eminent naturalists and philosophers; for instance, by Wallace, Huxley, +Lyell, Vogt, Lubbock, Buchner, Rolle, etc. (1. As the works of the first- +named authors are so well known, I need not give the titles; but as those +of the latter are less well known in England, I will give them:--'Sechs +Vorlesungen über die Darwin'sche Theorie:' zweite Auflage, 1868, von Dr L. +Buchner; translated into French under the title 'Conférences sur la Théorie +Darwinienne,' 1869. 'Der Mensch im Lichte der Darwin'sche Lehre,' 1865, +von Dr. F. Rolle. I will not attempt to give references to all the authors +who have taken the same side of the question. Thus G. Canestrini has +published ('Annuario della Soc. d. Nat.,' Modena, 1867, page 81) a very +curious paper on rudimentary characters, as bearing on the origin of man. +Another work has (1869) been published by Dr. Francesco Barrago, bearing in +Italian the title of "Man, made in the image of God, was also made in the +image of the ape."), and especially by Haeckel. This last naturalist, +besides his great work, 'Generelle Morphologie' (1866), has recently (1868, +with a second edition in 1870), published his 'Natürliche +Schöpfungsgeschichte,' in which he fully discusses the genealogy of man. +If this work had appeared before my essay had been written, I should +probably never have completed it. Almost all the conclusions at which I +have arrived I find confirmed by this naturalist, whose knowledge on many +points is much fuller than mine. Wherever I have added any fact or view +from Prof. Haeckel's writings, I give his authority in the text; other +statements I leave as they originally stood in my manuscript, occasionally +giving in the foot-notes references to his works, as a confirmation of the +more doubtful or interesting points. + +During many years it has seemed to me highly probable that sexual selection +has played an important part in differentiating the races of man; but in my +'Origin of Species' (first edition, page 199) I contented myself by merely +alluding to this belief. When I came to apply this view to man, I found it +indispensable to treat the whole subject in full detail. (2. Prof. +Haeckel was the only author who, at the time when this work first appeared, +had discussed the subject of sexual selection, and had seen its full +importance, since the publication of the 'Origin'; and this he did in a +very able manner in his various works.) Consequently the second part of +the present work, treating of sexual selection, has extended to an +inordinate length, compared with the first part; but this could not be +avoided. + +I had intended adding to the present volumes an essay on the expression of +the various emotions by man and the lower animals. My attention was called +to this subject many years ago by Sir Charles Bell's admirable work. This +illustrious anatomist maintains that man is endowed with certain muscles +solely for the sake of expressing his emotions. As this view is obviously +opposed to the belief that man is descended from some other and lower form, +it was necessary for me to consider it. I likewise wished to ascertain how +far the emotions are expressed in the same manner by the different races of +man. But owing to the length of the present work, I have thought it better +to reserve my essay for separate publication. + + +PART I. THE DESCENT OR ORIGIN OF MAN. + + +CHAPTER I. + +THE EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM. + +Nature of the evidence bearing on the origin of man--Homologous structures +in man and the lower animals--Miscellaneous points of correspondence-- +Development--Rudimentary structures, muscles, sense-organs, hair, bones, +reproductive organs, etc.--The bearing of these three great classes of +facts on the origin of man. + +He who wishes to decide whether man is the modified descendant of some pre- +existing form, would probably first enquire whether man varies, however +slightly, in bodily structure and in mental faculties; and if so, whether +the variations are transmitted to his offspring in accordance with the laws +which prevail with the lower animals. Again, are the variations the +result, as far as our ignorance permits us to judge, of the same general +causes, and are they governed by the same general laws, as in the case of +other organisms; for instance, by correlation, the inherited effects of use +and disuse, etc.? Is man subject to similar malconformations, the result +of arrested development, of reduplication of parts, etc., and does he +display in any of his anomalies reversion to some former and ancient type +of structure? It might also naturally be enquired whether man, like so +many other animals, has given rise to varieties and sub-races, differing +but slightly from each other, or to races differing so much that they must +be classed as doubtful species? How are such races distributed over the +world; and how, when crossed, do they react on each other in the first and +succeeding generations? And so with many other points. + +The enquirer would next come to the important point, whether man tends to +increase at so rapid a rate, as to lead to occasional severe struggles for +existence; and consequently to beneficial variations, whether in body or +mind, being preserved, and injurious ones eliminated. Do the races or +species of men, whichever term may be applied, encroach on and replace one +another, so that some finally become extinct? We shall see that all these +questions, as indeed is obvious in respect to most of them, must be +answered in the affirmative, in the same manner as with the lower animals. +But the several considerations just referred to may be conveniently +deferred for a time: and we will first see how far the bodily structure of +man shews traces, more or less plain, of his descent from some lower form. +In succeeding chapters the mental powers of man, in comparison with those +of the lower animals, will be considered. + +THE BODILY STRUCTURE OF MAN. + +It is notorious that man is constructed on the same general type or model +as other mammals. All the bones in his skeleton can be compared with +corresponding bones in a monkey, bat, or seal. So it is with his muscles, +nerves, blood-vessels and internal viscera. The brain, the most important +of all the organs, follows the same law, as shewn by Huxley and other +anatomists. Bischoff (1. 'Grosshirnwindungen des Menschen,' 1868, s. 96. +The conclusions of this author, as well as those of Gratiolet and Aeby, +concerning the brain, will be discussed by Prof. Huxley in the Appendix +alluded to in the Preface to this edition.), who is a hostile witness, +admits that every chief fissure and fold in the brain of man has its +analogy in that of the orang; but he adds that at no period of development +do their brains perfectly agree; nor could perfect agreement be expected, +for otherwise their mental powers would have been the same. Vulpian (2. +'Lec. sur la Phys.' 1866, page 890, as quoted by M. Dally, 'L'Ordre des +Primates et le Transformisme,' 1868, page 29.), remarks: "Les différences +réelles qui existent entre l'encephale de l'homme et celui des singes +supérieurs, sont bien minimes. Il ne faut pas se faire d'illusions a cet +égard. L'homme est bien plus près des singes anthropomorphes par les +caractères anatomiques de son cerveau que ceux-ci ne le sont non seulement +des autres mammifères, mais même de certains quadrumanes, des guenons et +des macaques." But it would be superfluous here to give further details on +the correspondence between man and the higher mammals in the structure of +the brain and all other parts of the body. + +It may, however, be worth while to specify a few points, not directly or +obviously connected with structure, by which this correspondence or +relationship is well shewn. + +Man is liable to receive from the lower animals, and to communicate to +them, certain diseases, as hydrophobia, variola, the glanders, syphilis, +cholera, herpes, etc. (3. Dr. W. Lauder Lindsay has treated this subject +at some length in the 'Journal of Mental Science,' July 1871; and in the +'Edinburgh Veterinary Review,' July 1858.); and this fact proves the close +similarity (4. A Reviewer has criticised ('British Quarterly Review,' Oct. +1st, 1871, page 472) what I have here said with much severity and contempt; +but as I do not use the term identity, I cannot see that I am greatly in +error. There appears to me a strong analogy between the same infection or +contagion producing the same result, or one closely similar, in two +distinct animals, and the testing of two distinct fluids by the same +chemical reagent.) of their tissues and blood, both in minute structure and +composition, far more plainly than does their comparison under the best +microscope, or by the aid of the best chemical analysis. Monkeys are +liable to many of the same non-contagious diseases as we are; thus Rengger +(5. 'Naturgeschichte der Säugethiere von Paraguay,' 1830, s. 50.), who +carefully observed for a long time the Cebus Azarae in its native land, +found it liable to catarrh, with the usual symptoms, and which, when often +recurrent, led to consumption. These monkeys suffered also from apoplexy, +inflammation of the bowels, and cataract in the eye. The younger ones when +shedding their milk-teeth often died from fever. Medicines produced the +same effect on them as on us. Many kinds of monkeys have a strong taste +for tea, coffee, and spiritous liquors: they will also, as I have myself +seen, smoke tobacco with pleasure. (6. The same tastes are common to some +animals much lower in the scale. Mr. A. Nichols informs me that he kept in +Queensland, in Australia, three individuals of the Phaseolarctus cinereus; +and that, without having been taught in any way, they acquired a strong +taste for rum, and for smoking tobacco.) Brehm asserts that the natives of +north-eastern Africa catch the wild baboons by exposing vessels with strong +beer, by which they are made drunk. He has seen some of these animals, +which he kept in confinement, in this state; and he gives a laughable +account of their behaviour and strange grimaces. On the following morning +they were very cross and dismal; they held their aching heads with both +hands, and wore a most pitiable expression: when beer or wine was offered +them, they turned away with disgust, but relished the juice of lemons. (7. +Brehm, 'Thierleben,' B. i. 1864, s. 75, 86. On the Ateles, s. 105. For +other analogous statements, see s. 25, 107.) An American monkey, an +Ateles, after getting drunk on brandy, would never touch it again, and thus +was wiser than many men. These trifling facts prove how similar the nerves +of taste must be in monkeys and man, and how similarly their whole nervous +system is affected. + +Man is infested with internal parasites, sometimes causing fatal effects; +and is plagued by external parasites, all of which belong to the same +genera or families as those infesting other mammals, and in the case of +scabies to the same species. (8. Dr. W. Lauder Lindsay, 'Edinburgh Vet. +Review,' July 1858, page 13.) Man is subject, like other mammals, birds, +and even insects (9. With respect to insects see Dr. Laycock, "On a +General Law of Vital Periodicity," 'British Association,' 1842. Dr. +Macculloch, 'Silliman's North American Journal of Science,' vol. XVII. page +305, has seen a dog suffering from tertian ague. Hereafter I shall return +to this subject.), to that mysterious law, which causes certain normal +processes, such as gestation, as well as the maturation and duration of +various diseases, to follow lunar periods. His wounds are repaired by the +same process of healing; and the stumps left after the amputation of his +limbs, especially during an early embryonic period, occasionally possess +some power of regeneration, as in the lowest animals. (10. I have given +the evidence on this head in my 'Variation of Animals and Plants under +Domestication,' vol. ii. page 15, and more could be added.) + +The whole process of that most important function, the reproduction of the +species, is strikingly the same in all mammals, from the first act of +courtship by the male (11. Mares e diversis generibus Quadrumanorum sine +dubio dignoscunt feminas humanas a maribus. Primum, credo, odoratu, postea +aspectu. Mr. Youatt, qui diu in Hortis Zoologicis (Bestiariis) medicus +animalium erat, vir in rebus observandis cautus et sagax, hoc mihi +certissime probavit, et curatores ejusdem loci et alii e ministris +confirmaverunt. Sir Andrew Smith et Brehm notabant idem in Cynocephalo. +Illustrissimus Cuvier etiam narrat multa de hac re, qua ut opinor, nihil +turpius potest indicari inter omnia hominibus et Quadrumanis communia. +Narrat enim Cynocephalum quendam in furorem incidere aspectu feminarum +aliquarem, sed nequaquam accendi tanto furore ab omnibus. Semper eligebat +juniores, et dignoscebat in turba, et advocabat voce gestuque.), to the +birth and nurturing of the young. Monkeys are born in almost as helpless a +condition as our own infants; and in certain genera the young differ fully +as much in appearance from the adults, as do our children from their +full-grown parents. (12. This remark is made with respect to Cynocephalus +and the anthropomorphous apes by Geoffroy Saint-Hilaire and F. Cuvier, +'Histoire Nat. des Mammifères,' tom. i. 1824.) It has been urged by some +writers, as an important distinction, that with man the young arrive at +maturity at a much later age than with any other animal: but if we look to +the races of mankind which inhabit tropical countries the difference is not +great, for the orang is believed not to be adult till the age of from ten +to fifteen years. (13. Huxley, 'Man's Place in Nature,' 1863, p. 34.) +Man differs from woman in size, bodily strength, hairiness, etc., as well +as in mind, in the same manner as do the two sexes of many mammals. So +that the correspondence in general structure, in the minute structure of +the tissues, in chemical composition and in constitution, between man and +the higher animals, especially the anthropomorphous apes, is extremely +close. + +EMBRYONIC DEVELOPMENT. + +[Fig. 1. Shows a human embryo, from Ecker, and a dog embryo, from +Bischoff. Labelled in each are: + +a. Fore-brain, cerebral hemispheres, etc. +b. Mid-brain, corpora quadrigemina. +c. Hind-brain, cerebellum, medulla oblongata. +d. Eye. +e. Ear. +f. First visceral arch. +g. Second visceral arch. +H. Vertebral columns and muscles in process of development. +i. Anterior extremities. +K. Posterior extremities. +L. Tail or os coccyx.] + +Man is developed from an ovule, about the 125th of an inch in diameter, +which differs in no respect from the ovules of other animals. The embryo +itself at a very early period can hardly be distinguished from that of +other members of the vertebrate kingdom. At this period the arteries run +in arch-like branches, as if to carry the blood to branchiae which are not +present in the higher Vertebrata, though the slits on the sides of the neck +still remain (see f, g, fig. 1), marking their former position. At a +somewhat later period, when the extremities are developed, "the feet of +lizards and mammals," as the illustrious Von Baer remarks, "the wings and +feet of birds, no less than the hands and feet of man, all arise from the +same fundamental form." It is, says Prof. Huxley (14. 'Man's Place in +Nature,' 1863, p. 67.), "quite in the later stages of development that the +young human being presents marked differences from the young ape, while the +latter departs as much from the dog in its developments, as the man does. +Startling as this last assertion may appear to be, it is demonstrably +true." + +As some of my readers may never have seen a drawing of an embryo, I have +given one of man and another of a dog, at about the same early stage of +development, carefully copied from two works of undoubted accuracy. (15. +The human embryo (upper fig.) is from Ecker, 'Icones Phys.,' 1851-1859, +tab. xxx. fig. 2. This embryo was ten lines in length, so that the drawing +is much magnified. The embryo of the dog is from Bischoff, +'Entwicklungsgeschichte des Hunde-Eies,' 1845, tab. xi. fig. 42B. This +drawing is five times magnified, the embryo being twenty-five days old. +The internal viscera have been omitted, and the uterine appendages in both +drawings removed. I was directed to these figures by Prof. Huxley, from +whose work, 'Man's Place in Nature,' the idea of giving them was taken. +Haeckel has also given analogous drawings in his 'Schopfungsgeschichte.') + +After the foregoing statements made by such high authorities, it would be +superfluous on my part to give a number of borrowed details, shewing that +the embryo of man closely resembles that of other mammals. It may, +however, be added, that the human embryo likewise resembles certain low +forms when adult in various points of structure. For instance, the heart +at first exists as a simple pulsating vessel; the excreta are voided +through a cloacal passage; and the os coccyx projects like a true tail, +"extending considerably beyond the rudimentary legs." (16. Prof. Wyman in +'Proceedings of the American Academy of Sciences,' vol. iv. 1860, p. 17.) +In the embryos of all air-breathing vertebrates, certain glands, called the +corpora Wolffiana, correspond with, and act like the kidneys of mature +fishes. (17. Owen, 'Anatomy of Vertebrates,' vol. i. p. 533.) Even at a +later embryonic period, some striking resemblances between man and the +lower animals may be observed. Bischoff says that "the convolutions of the +brain in a human foetus at the end of the seventh month reach about the +same stage of development as in a baboon when adult." (18. 'Die +Grosshirnwindungen des Menschen,' 1868, s. 95.) The great toe, as +Professor Owen remarks (19. 'Anatomy of Vertebrates,' vol. ii. p. 553.), +"which forms the fulcrum when standing or walking, is perhaps the most +characteristic peculiarity in the human structure;" but in an embryo, about +an inch in length, Prof. Wyman (20. 'Proc. Soc. Nat. Hist.' Boston, 1863, +vol. ix. p. 185.) found "that the great toe was shorter than the others; +and, instead of being parallel to them, projected at an angle from the side +of the foot, thus corresponding with the permanent condition of this part +in the quadrumana." I will conclude with a quotation from Huxley (21. +'Man's Place in Nature,' p. 65.) who after asking, does man originate in a +different way from a dog, bird, frog or fish? says, "the reply is not +doubtful for a moment; without question, the mode of origin, and the early +stages of the development of man, are identical with those of the animals +immediately below him in the scale: without a doubt in these respects, he +is far nearer to apes than the apes are to the dog." + +RUDIMENTS. + +This subject, though not intrinsically more important than the two last, +will for several reasons be treated here more fully. (22. I had written a +rough copy of this chapter before reading a valuable paper, "Caratteri +rudimentali in ordine all' origine dell' uomo" ('Annuario della Soc. d. +Naturalisti,' Modena, 1867, p. 81), by G. Canestrini, to which paper I am +considerably indebted. Haeckel has given admirable discussions on this +whole subject, under the title of Dysteleology, in his 'Generelle +Morphologie' and 'Schöpfungsgeschichte.') Not one of the higher animals +can be named which does not bear some part in a rudimentary condition; and +man forms no exception to the rule. Rudimentary organs must be +distinguished from those that are nascent; though in some cases the +distinction is not easy. The former are either absolutely useless, such as +the mammae of male quadrupeds, or the incisor teeth of ruminants which +never cut through the gums; or they are of such slight service to their +present possessors, that we can hardly suppose that they were developed +under the conditions which now exist. Organs in this latter state are not +strictly rudimentary, but they are tending in this direction. Nascent +organs, on the other hand, though not fully developed, are of high service +to their possessors, and are capable of further development. Rudimentary +organs are eminently variable; and this is partly intelligible, as they are +useless, or nearly useless, and consequently are no longer subjected to +natural selection. They often become wholly suppressed. When this occurs, +they are nevertheless liable to occasional reappearance through reversion-- +a circumstance well worthy of attention. + +The chief agents in causing organs to become rudimentary seem to have been +disuse at that period of life when the organ is chiefly used (and this is +generally during maturity), and also inheritance at a corresponding period +of life. The term "disuse" does not relate merely to the lessened action +of muscles, but includes a diminished flow of blood to a part or organ, +from being subjected to fewer alternations of pressure, or from becoming in +any way less habitually active. Rudiments, however, may occur in one sex +of those parts which are normally present in the other sex; and such +rudiments, as we shall hereafter see, have often originated in a way +distinct from those here referred to. In some cases, organs have been +reduced by means of natural selection, from having become injurious to the +species under changed habits of life. The process of reduction is probably +often aided through the two principles of compensation and economy of +growth; but the later stages of reduction, after disuse has done all that +can fairly be attributed to it, and when the saving to be effected by the +economy of growth would be very small (23. Some good criticisms on this +subject have been given by Messrs. Murie and Mivart, in 'Transact. +Zoological Society,' 1869, vol. vii. p. 92.), are difficult to understand. +The final and complete suppression of a part, already useless and much +reduced in size, in which case neither compensation nor economy can come +into play, is perhaps intelligible by the aid of the hypothesis of +pangenesis. But as the whole subject of rudimentary organs has been +discussed and illustrated in my former works (24. 'Variation of Animals +and Plants under Domestication,' vol. ii pp. 317 and 397. See also 'Origin +of Species,' 5th Edition p. 535.), I need here say no more on this head. + +Rudiments of various muscles have been observed in many parts of the human +body (25. For instance, M. Richard ('Annales des Sciences Nat.,' 3rd +series, Zoolog. 1852, tom. xviii. p. 13) describes and figures rudiments of +what he calls the "muscle pedieux de la main," which he says is sometimes +"infiniment petit." Another muscle, called "le tibial posterieur," is +generally quite absent in the hand, but appears from time to time in a more +or less rudimentary condition.); and not a few muscles, which are regularly +present in some of the lower animals can occasionally be detected in man in +a greatly reduced condition. Every one must have noticed the power which +many animals, especially horses, possess of moving or twitching their skin; +and this is effected by the panniculus carnosus. Remnants of this muscle +in an efficient state are found in various parts of our bodies; for +instance, the muscle on the forehead, by which the eyebrows are raised. +The platysma myoides, which is well developed on the neck, belongs to this +system. Prof. Turner, of Edinburgh, has occasionally detected, as he +informs me, muscular fasciculi in five different situations, namely in the +axillae, near the scapulae, etc., all of which must be referred to the +system of the panniculus. He has also shewn (26. Prof. W. Turner, +'Proceedings of the Royal Society of Edinburgh,' 1866-67, p. 65.) that the +musculus sternalis or sternalis brutorum, which is not an extension of the +rectus abdominalis, but is closely allied to the panniculus, occurred in +the proportion of about three per cent. in upwards of 600 bodies: he adds, +that this muscle affords "an excellent illustration of the statement that +occasional and rudimentary structures are especially liable to variation in +arrangement." + +Some few persons have the power of contracting the superficial muscles on +their scalps; and these muscles are in a variable and partially rudimentary +condition. M. A. de Candolle has communicated to me a curious instance of +the long-continued persistence or inheritance of this power, as well as of +its unusual development. He knows a family, in which one member, the +present head of the family, could, when a youth, pitch several heavy books +from his head by the movement of the scalp alone; and he won wagers by +performing this feat. His father, uncle, grandfather, and his three +children possess the same power to the same unusual degree. This family +became divided eight generations ago into two branches; so that the head of +the above-mentioned branch is cousin in the seventh degree to the head of +the other branch. This distant cousin resides in another part of France; +and on being asked whether he possessed the same faculty, immediately +exhibited his power. This case offers a good illustration how persistent +may be the transmission of an absolutely useless faculty, probably derived +from our remote semi-human progenitors; since many monkeys have, and +frequently use the power, of largely moving their scalps up and down. (27. +See my 'Expression of the Emotions in Man and Animals,' 1872, p. 144.) + +The extrinsic muscles which serve to move the external ear, and the +intrinsic muscles which move the different parts, are in a rudimentary +condition in man, and they all belong to the system of the panniculus; they +are also variable in development, or at least in function. I have seen one +man who could draw the whole ear forwards; other men can draw it upwards; +another who could draw it backwards (28. Canestrini quotes Hyrtl. +('Annuario della Soc. dei Naturalisti,' Modena, 1867, p. 97) to the same +effect.); and from what one of these persons told me, it is probable that +most of us, by often touching our ears, and thus directing our attention +towards them, could recover some power of movement by repeated trials. The +power of erecting and directing the shell of the ears to the various points +of the compass, is no doubt of the highest service to many animals, as they +thus perceive the direction of danger; but I have never heard, on +sufficient evidence, of a man who possessed this power, the one which might +be of use to him. The whole external shell may be considered a rudiment, +together with the various folds and prominences (helix and anti-helix, +tragus and anti-tragus, etc.) which in the lower animals strengthen and +support the ear when erect, without adding much to its weight. Some +authors, however, suppose that the cartilage of the shell serves to +transmit vibrations to the acoustic nerve; but Mr. Toynbee (29. 'The +Diseases of the Ear,' by J. Toynbee, F.R.S., 1860, p. 12. A distinguished +physiologist, Prof. Preyer, informs me that he had lately been +experimenting on the function of the shell of the ear, and has come to +nearly the same conclusion as that given here.), after collecting all the +known evidence on this head, concludes that the external shell is of no +distinct use. The ears of the chimpanzee and orang are curiously like +those of man, and the proper muscles are likewise but very slightly +developed. (30. Prof. A. Macalister, 'Annals and Magazine of Natural +History,' vol. vii. 1871, p. 342.) I am also assured by the keepers in the +Zoological Gardens that these animals never move or erect their ears; so +that they are in an equally rudimentary condition with those of man, as far +as function is concerned. Why these animals, as well as the progenitors of +man, should have lost the power of erecting their ears, we cannot say. It +may be, though I am not satisfied with this view, that owing to their +arboreal habits and great strength they were but little exposed to danger, +and so during a lengthened period moved their ears but little, and thus +gradually lost the power of moving them. This would be a parallel case +with that of those large and heavy birds, which, from ihabiting oceanic +islands, have not been exposed to the attacks of beasts of prey, and have +consequently lost the power of using their wings for flight. The inability +to move the ears in man and several apes is, however, partly compensated by +the freedom with which they can move the head in a horizontal plane, so as +to catch sounds from all directions. It has been asserted that the ear of +man alone possesses a lobule; but "a rudiment of it is found in the +gorilla" (31. Mr. St. George Mivart, 'Elementary Anatomy,' 1873, p. 396.); +and, as I hear from Prof. Preyer, it is not rarely absent in the negro. + +[Fig. 2. Human Ear, modelled and drawn by Mr. Woolner. The projecting +point is labelled a.] + +The celebrated sculptor, Mr. Woolner, informs me of one little peculiarity +in the external ear, which he has often observed both in men and women, and +of which he perceived the full significance. His attention was first +called to the subject whilst at work on his figure of Puck, to which he had +given pointed ears. He was thus led to examine the ears of various +monkeys, and subsequently more carefully those of man. The peculiarity +consists in a little blunt point, projecting from the inwardly folded +margin, or helix. When present, it is developed at birth, and, according +to Prof. Ludwig Meyer, more frequently in man than in woman. Mr. Woolner +made an exact model of one such case, and sent me the accompanying drawing. +(Fig. 2). These points not only project inwards towards the centre of the +ear, but often a little outwards from its plane, so as to be visible when +the head is viewed from directly in front or behind. They are variable in +size, and somewhat in position, standing either a little higher or lower; +and they sometimes occur on one ear and not on the other. They are not +confined to mankind, for I observed a case in one of the spider-monkeys +(Ateles beelzebuth) in our Zoological Gardens; and Mr. E. Ray Lankester +informs me of another case in a chimpanzee in the gardens at Hamburg. The +helix obviously consists of the extreme margin of the ear folded inwards; +and this folding appears to be in some manner connected with the whole +external ear being permanently pressed backwards. In many monkeys, which +do not stand high in the order, as baboons and some species of macacus (32. +See also some remarks, and the drawings of the ears of the Lemuroidea, in +Messrs. Murie and Mivart's excellent paper in 'Transactions of the +Zoological Society,' vol. vii. 1869, pp. 6 and 90.), the upper portion of +the ear is slightly pointed, and the margin is not at all folded inwards; +but if the margin were to be thus folded, a slight point would necessarily +project inwards towards the centre, and probably a little outwards from the +plane of the ear; and this I believe to be their origin in many cases. On +the other hand, Prof. L. Meyer, in an able paper recently published (33. +'Über das Darwin'sche Spitzohr,' Archiv fur Path. Anat. und Phys., 1871, p. +485.), maintains that the whole case is one of mere variability; and that +the projections are not real ones, but are due to the internal cartilage on +each side of the points not having been fully developed. I am quite ready +to admit that this is the correct explanation in many instances, as in +those figured by Prof. Meyer, in which there are several minute points, or +the whole margin is sinuous. I have myself seen, through the kindness of +Dr. L. Down, the ear of a microcephalous idiot, on which there is a +projection on the outside of the helix, and not on the inward folded edge, +so that this point can have no relation to a former apex of the ear. +Nevertheless in some cases, my original view, that the points are vestiges +of the tips of formerly erect and pointed ears, still seems to me probable. +I think so from the frequency of their occurrence, and from the general +correspondence in position with that of the tip of a pointed ear. In one +case, of which a photograph has been sent me, the projection is so large, +that supposing, in accordance with Prof. Meyer's view, the ear to be made +perfect by the equal development of the cartilage throughout the whole +extent of the margin, it would have covered fully one-third of the whole +ear. Two cases have been communicated to me, one in North America, and the +other in England, in which the upper margin is not at all folded inwards, +but is pointed, so that it closely resembles the pointed ear of an ordinary +quadruped in outline. In one of these cases, which was that of a young +child, the father compared the ear with the drawing which I have given (34. +'The Expression of the Emotions,' p. 136.) of the ear of a monkey, the +Cynopithecus niger, and says that their outlines are closely similar. If, +in these two cases, the margin had been folded inwards in the normal +manner, an inward projection must have been formed. I may add that in two +other cases the outline still remains somewhat pointed, although the margin +of the upper part of the ear is normally folded inwards--in one of them, +however, very narrowly. [Fig.3. Foetus of an Orang(?). Exact copy of a +photograph, shewing the form of the ear at this early age.] The following +woodcut (No. 3) is an accurate copy of a photograph of the foetus of an +orang (kindly sent me by Dr. Nitsche), in which it may be seen how +different the pointed outline of the ear is at this period from its adult +condition, when it bears a close general resemblance to that of man. It is +evident that the folding over of the tip of such an ear, unless it changed +greatly during its further development, would give rise to a point +projecting inwards. On the whole, it still seems to me probable that the +points in question are in some cases, both in man and apes, vestiges of a +former condition. + +The nictitating membrane, or third eyelid, with its accessory muscles and +other structures, is especially well developed in birds, and is of much +functional importance to them, as it can be rapidly drawn across the whole +eye-ball. It is found in some reptiles and amphibians, and in certain +fishes, as in sharks. It is fairly well developed in the two lower +divisions of the mammalian series, namely, in the monotremata and +marsupials, and in some few of the higher mammals, as in the walrus. But +in man, the quadrumana, and most other mammals, it exists, as is admitted +by all anatomists, as a mere rudiment, called the semilunar fold. (35. +Muller's 'Elements of Physiology,' Eng. translat. 1842, vol. ii. p. 1117. +Owen, 'Anatomy of Vertebrates,' vol. iii. p. 260; ibid. on the Walrus, +'Proceedings of the Zoological Society,' November 8, 1854. See also R. +Knox, 'Great Artists and Anatomists,' p. 106. This rudiment apparently is +somewhat larger in Negroes and Australians than in Europeans, see Carl +Vogt, 'Lectures on Man,' Eng. translat. p. 129.) + +The sense of smell is of the highest importance to the greater number of +mammals--to some, as the ruminants, in warning them of danger; to others, +as the Carnivora, in finding their prey; to others, again, as the wild +boar, for both purposes combined. But the sense of smell is of extremely +slight service, if any, even to the dark coloured races of men, in whom it +is much more highly developed than in the white and civilised races. (36. +The account given by Humboldt of the power of smell possessed by the +natives of South America is well known, and has been confirmed by others. +M. Houzeau ('Études sur les Facultés Mentales,' etc., tom. i. 1872, p. 91) +asserts that he repeatedly made experiments, and proved that Negroes and +Indians could recognise persons in the dark by their odour. Dr. W. Ogle +has made some curious observations on the connection between the power of +smell and the colouring matter of the mucous membrane of the olfactory +region as well as of the skin of the body. I have, therefore, spoken in +the text of the dark-coloured races having a finer sense of smell than the +white races. See his paper, 'Medico-Chirurgical Transactions,' London, +vol. liii. 1870, p. 276.) Nevertheless it does not warn them of danger, +nor guide them to their food; nor does it prevent the Esquimaux from +sleeping in the most fetid atmosphere, nor many savages from eating +half-putrid meat. In Europeans the power differs greatly in different +individuals, as I am assured by an eminent naturalist who possesses this +sense highly developed, and who has attended to the subject. Those who +believe in the principle of gradual evolution, will not readily admit that +the sense of smell in its present state was originally acquired by man, as +he now exists. He inherits the power in an enfeebled and so far +rudimentary condition, from some early progenitor, to whom it was highly +serviceable, and by whom it was continually used. In those animals which +have this sense highly developed, such as dogs and horses, the recollection +of persons and of places is strongly associated with their odour; and we +can thus perhaps understand how it is, as Dr. Maudsley has truly remarked +(37. 'The Physiology and Pathology of Mind,' 2nd ed. 1868, p. 134.), that +the sense of smell in man "is singularly effective in recalling vividly the +ideas and images of forgotten scenes and places." + +Man differs conspicuously from all the other primates in being almost +naked. But a few short straggling hairs are found over the greater part of +the body in the man, and fine down on that of the woman. The different +races differ much in hairiness; and in the individuals of the same race the +hairs are highly variable, not only in abundance, but likewise in position: +thus in some Europeans the shoulders are quite naked, whilst in others they +bear thick tufts of hair. (38. Eschricht, Über die Richtung der Haare am +menschlichen Körper, Muller's 'Archiv fur Anat. und Phys.' 1837, s. 47. I +shall often have to refer to this very curious paper.) There can be little +doubt that the hairs thus scattered over the body are the rudiments of the +uniform hairy coat of the lower animals. This view is rendered all the +more probable, as it is known that fine, short, and pale-coloured hairs on +the limbs and other parts of the body, occasionally become developed into +"thickset, long, and rather coarse dark hairs," when abnormally nourished +near old-standing inflamed surfaces. (39. Paget, 'Lectures on Surgical +Pathology,' 1853, vol. i. p. 71.) + +I am informed by Sir James Paget that often several members of a family +have a few hairs in their eyebrows much longer than the others; so that +even this slight peculiarity seems to be inherited. These hairs, too, seem +to have their representatives; for in the chimpanzee, and in certain +species of Macacus, there are scattered hairs of considerable length rising +from the naked skin above the eyes, and corresponding to our eyebrows; +similar long hairs project from the hairy covering of the superciliary +ridges in some baboons. + +The fine wool-like hair, or so-called lanugo, with which the human foetus +during the sixth month is thickly covered, offers a more curious case. It +is first developed, during the fifth month, on the eyebrows and face, and +especially round the mouth, where it is much longer than that on the head. +A moustache of this kind was observed by Eschricht (40. Eschricht, ibid. +s. 40, 47.) on a female foetus; but this is not so surprising a +circumstance as it may at first appear, for the two sexes generally +resemble each other in all external characters during an early period of +growth. The direction and arrangement of the hairs on all parts of the +foetal body are the same as in the adult, but are subject to much +variability. The whole surface, including even the forehead and ears, is +thus thickly clothed; but it is a significant fact that the palms of the +hands and the soles of the feet are quite naked, like the inferior surfaces +of all four extremities in most of the lower animals. As this can hardly +be an accidental coincidence, the woolly covering of the foetus probably +represents the first permanent coat of hair in those mammals which are born +hairy. Three or four cases have been recorded of persons born with their +whole bodies and faces thickly covered with fine long hairs; and this +strange condition is strongly inherited, and is correlated with an abnormal +condition of the teeth. (41. See my 'Variation of Animals and Plants +under Domestication,' vol. ii. p. 327. Prof. Alex. Brandt has recently +sent me an additional case of a father and son, born in Russia, with these +peculiarities. I have received drawings of both from Paris.) Prof. Alex. +Brandt informs me that he has compared the hair from the face of a man thus +characterised, aged thirty-five, with the lanugo of a foetus, and finds it +quite similar in texture; therefore, as he remarks, the case may be +attributed to an arrest of development in the hair, together with its +continued growth. Many delicate children, as I have been assured by a +surgeon to a hospital for children, have their backs covered by rather long +silky hairs; and such cases probably come under the same head. + +It appears as if the posterior molar or wisdom-teeth were tending to become +rudimentary in the more civilised races of man. These teeth are rather +smaller than the other molars, as is likewise the case with the +corresponding teeth in the chimpanzee and orang; and they have only two +separate fangs. They do not cut through the gums till about the +seventeenth year, and I have been assured that they are much more liable to +decay, and are earlier lost than the other teeth; but this is denied by +some eminent dentists. They are also much more liable to vary, both in +structure and in the period of their development, than the other teeth. +(42. Dr. Webb, 'Teeth in Man and the Anthropoid Apes,' as quoted by Dr. C. +Carter Blake in Anthropological Review, July 1867, p. 299.) In the +Melanian races, on the other hand, the wisdom-teeth are usually furnished +with three separate fangs, and are generally sound; they also differ from +the other molars in size, less than in the Caucasian races. (43. Owen, +'Anatomy of Vertebrates,' vol. iii. pp. 320, 321, and 325.) Prof. +Schaaffhausen accounts for this difference between the races by "the +posterior dental portion of the jaw being always shortened" in those that +are civilised (44. 'On the Primitive Form of the Skull,' Eng. translat., +in 'Anthropological Review,' Oct. 1868, p. 426), and this shortening may, I +presume, be attributed to civilised men habitually feeding on soft, cooked +food, and thus using their jaws less. I am informed by Mr. Brace that it +is becoming quite a common practice in the United States to remove some of +the molar teeth of children, as the jaw does not grow large enough for the +perfect development of the normal number. (45. Prof. Montegazza writes to +me from Florence, that he has lately been studying the last molar teeth in +the different races of man, and has come to the same conclusion as that +given in my text, viz., that in the higher or civilised races they are on +the road towards atrophy or elimination.) + +With respect to the alimentary canal, I have met with an account of only a +single rudiment, namely the vermiform appendage of the caecum. The caecum +is a branch or diverticulum of the intestine, ending in a cul-de-sac, and +is extremely long in many of the lower vegetable-feeding mammals. In the +marsupial koala it is actually more than thrice as long as the whole body. +(46. Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 416, 434, 441.) It is +sometimes produced into a long gradually-tapering point, and is sometimes +constricted in parts. It appears as if, in consequence of changed diet or +habits, the caecum had become much shortened in various animals, the +vermiform appendage being left as a rudiment of the shortened part. That +this appendage is a rudiment, we may infer from its small size, and from +the evidence which Prof. Canestrini (47. 'Annuario della Soc. d. Nat.' +Modena, 1867, p. 94.) has collected of its variability in man. It is +occasionally quite absent, or again is largely developed. The passage is +sometimes completely closed for half or two-thirds of its length, with the +terminal part consisting of a flattened solid expansion. In the orang this +appendage is long and convoluted: in man it arises from the end of the +short caecum, and is commonly from four to five inches in length, being +only about the third of an inch in diameter. Not only is it useless, but +it is sometimes the cause of death, of which fact I have lately heard two +instances: this is due to small hard bodies, such as seeds, entering the +passage, and causing inflammation. (48. M. C. Martins ("De l'Unité +Organique," in 'Revue des Deux Mondes,' June 15, 1862, p. 16) and Haeckel +('Generelle Morphologie,' B. ii. s. 278), have both remarked on the +singular fact of this rudiment sometimes causing death.) + +In some of the lower Quadrumana, in the Lemuridae and Carnivora, as well as +in many marsupials, there is a passage near the lower end of the humerus, +called the supra-condyloid foramen, through which the great nerve of the +fore limb and often the great artery pass. Now in the humerus of man, +there is generally a trace of this passage, which is sometimes fairly well +developed, being formed by a depending hook-like process of bone, completed +by a band of ligament. Dr. Struthers (49. With respect to inheritance, +see Dr. Struthers in the 'Lancet,' Feb. 15, 1873, and another important +paper, ibid. Jan. 24, 1863, p. 83. Dr. Knox, as I am informed, was the +first anatomist who drew attention to this peculiar structure in man; see +his 'Great Artists and Anatomists,' p. 63. See also an important memoir on +this process by Dr. Gruber, in the 'Bulletin de l'Acad. Imp. de St. +Petersbourg,' tom. xii. 1867, p. 448.), who has closely attended to the +subject, has now shewn that this peculiarity is sometimes inherited, as it +has occurred in a father, and in no less than four out of his seven +children. When present, the great nerve invariably passes through it; and +this clearly indicates that it is the homologue and rudiment of the +supra-condyloid foramen of the lower animals. Prof. Turner estimates, as +he informs me, that it occurs in about one per cent. of recent skeletons. +But if the occasional development of this structure in man is, as seems +probable, due to reversion, it is a return to a very ancient state of +things, because in the higher Quadrumana it is absent. + +There is another foramen or perforation in the humerus, occasionally +present in man, which may be called the inter-condyloid. This occurs, but +not constantly, in various anthropoid and other apes (50. Mr. St. George +Mivart, 'Transactions Phil. Soc.' 1867, p. 310.), and likewise in many of +the lower animals. It is remarkable that this perforation seems to have +been present in man much more frequently during ancient times than +recently. Mr. Busk (51. "On the Caves of Gibraltar," 'Transactions of the +International Congress of Prehistoric Archaeology,' Third Session, 1869, p. +159. Prof. Wyman has lately shewn (Fourth Annual Report, Peabody Museum, +1871, p. 20), that this perforation is present in thirty-one per cent. of +some human remains from ancient mounds in the Western United States, and in +Florida. It frequently occurs in the negro.) has collected the following +evidence on this head: Prof. Broca "noticed the perforation in four and a +half per cent. of the arm-bones collected in the 'Cimetière du Sud,' at +Paris; and in the Grotto of Orrony, the contents of which are referred to +the Bronze period, as many as eight humeri out of thirty-two were +perforated; but this extraordinary proportion, he thinks, might be due to +the cavern having been a sort of 'family vault.' Again, M. Dupont found +thirty per cent. of perforated bones in the caves of the Valley of the +Lesse, belonging to the Reindeer period; whilst M. Leguay, in a sort of +dolmen at Argenteuil, observed twenty-five per cent. to be perforated; and +M. Pruner-Bey found twenty-six per cent. in the same condition in bones +from Vaureal. Nor should it be left unnoticed that M. Pruner-Bey states +that this condition is common in Guanche skeletons." It is an interesting +fact that ancient races, in this and several other cases, more frequently +present structures which resemble those of the lower animals than do the +modern. One chief cause seems to be that the ancient races stand somewhat +nearer in the long line of descent to their remote animal-like progenitors. + +In man, the os coccyx, together with certain other vertebrae hereafter to +be described, though functionless as a tail, plainly represent this part in +other vertebrate animals. At an early embryonic period it is free, and +projects beyond the lower extremities; as may be seen in the drawing (Fig. +1.) of a human embryo. Even after birth it has been known, in certain rare +and anomalous cases (52. Quatrefages has lately collected the evidence on +this subject. 'Revue des Cours Scientifiques,' 1867-1868, p. 625. In 1840 +Fleischmann exhibited a human foetus bearing a free tail, which, as is not +always the case, included vertebral bodies; and this tail was critically +examined by the many anatomists present at the meeting of naturalists at +Erlangen (see Marshall in Niederlandischen Archiv für Zoologie, December +1871).), to form a small external rudiment of a tail. The os coccyx is +short, usually including only four vertebrae, all anchylosed together: and +these are in a rudimentary condition, for they consist, with the exception +of the basal one, of the centrum alone. (53. Owen, 'On the Nature of +Limbs,' 1849, p. 114.) They are furnished with some small muscles; one of +which, as I am informed by Prof. Turner, has been expressly described by +Theile as a rudimentary repetition of the extensor of the tail, a muscle +which is so largely developed in many mammals. + +The spinal cord in man extends only as far downwards as the last dorsal or +first lumbar vertebra; but a thread-like structure (the filum terminale) +runs down the axis of the sacral part of the spinal canal, and even along +the back of the coccygeal bones. The upper part of this filament, as Prof. +Turner informs me, is undoubtedly homologous with the spinal cord; but the +lower part apparently consists merely of the pia mater, or vascular +investing membrane. Even in this case the os coccyx may be said to possess +a vestige of so important a structure as the spinal cord, though no longer +enclosed within a bony canal. The following fact, for which I am also +indebted to Prof. Turner, shews how closely the os coccyx corresponds with +the true tail in the lower animals: Luschka has recently discovered at the +extremity of the coccygeal bones a very peculiar convoluted body, which is +continuous with the middle sacral artery; and this discovery led Krause and +Meyer to examine the tail of a monkey (Macacus), and of a cat, in both of +which they found a similarly convoluted body, though not at the extremity. + +The reproductive system offers various rudimentary structures; but these +differ in one important respect from the foregoing cases. Here we are not +concerned with the vestige of a part which does not belong to the species +in an efficient state, but with a part efficient in the one sex, and +represented in the other by a mere rudiment. Nevertheless, the occurrence +of such rudiments is as difficult to explain, on the belief of the separate +creation of each species, as in the foregoing cases. Hereafter I shall +have to recur to these rudiments, and shall shew that their presence +generally depends merely on inheritance, that is, on parts acquired by one +sex having been partially transmitted to the other. I will in this place +only give some instances of such rudiments. It is well known that in the +males of all mammals, including man, rudimentary mammae exist. These in +several instances have become well developed, and have yielded a copious +supply of milk. Their essential identity in the two sexes is likewise +shewn by their occasional sympathetic enlargement in both during an attack +of the measles. The vesicula prostatica, which has been observed in many +male mammals, is now universally acknowledged to be the homologue of the +female uterus, together with the connected passage. It is impossible to +read Leuckart's able description of this organ, and his reasoning, without +admitting the justness of his conclusion. This is especially clear in the +case of those mammals in which the true female uterus bifurcates, for in +the males of these the vesicula likewise bifurcates. (54. Leuckart, in +Todd's 'Cyclopaedia of Anatomy' 1849-52, vol. iv. p. 1415. In man this +organ is only from three to six lines in length, but, like so many other +rudimentary parts, it is variable in development as well as in other +characters.) Some other rudimentary structures belonging to the +reproductive system might have been here adduced. (55. See, on this +subject, Owen, 'Anatomy of Vertebrates,' vol. iii. pp. 675, 676, 706.) + +The bearing of the three great classes of facts now given is unmistakeable. +But it would be superfluous fully to recapitulate the line of argument +given in detail in my 'Origin of Species.' The homological construction of +the whole frame in the members of the same class is intelligible, if we +admit their descent from a common progenitor, together with their +subsequent adaptation to diversified conditions. On any other view, the +similarity of pattern between the hand of a man or monkey, the foot of a +horse, the flipper of a seal, the wing of a bat, etc., is utterly +inexplicable. (56. Prof. Bianconi, in a recently published work, +illustrated by admirable engravings ('La Théorie Darwinienne et la création +dite indépendante,' 1874), endeavours to shew that homological structures, +in the above and other cases, can be fully explained on mechanical +principles, in accordance with their uses. No one has shewn so well, how +admirably such structures are adapted for their final purpose; and this +adaptation can, as I believe, be explained through natural selection. In +considering the wing of a bat, he brings forward (p. 218) what appears to +me (to use Auguste Comte's words) a mere metaphysical principle, namely, +the preservation "in its integrity of the mammalian nature of the animal." +In only a few cases does he discuss rudiments, and then only those parts +which are partially rudimentary, such as the little hoofs of the pig and +ox, which do not touch the ground; these he shews clearly to be of service +to the animal. It is unfortunate that he did not consider such cases as +the minute teeth, which never cut through the jaw in the ox, or the mammae +of male quadrupeds, or the wings of certain beetles, existing under the +soldered wing-covers, or the vestiges of the pistil and stamens in various +flowers, and many other such cases. Although I greatly admire Prof. +Bianconi's work, yet the belief now held by most naturalists seems to me +left unshaken, that homological structures are inexplicable on the +principle of mere adaptation.) It is no scientific explanation to assert +that they have all been formed on the same ideal plan. With respect to +development, we can clearly understand, on the principle of variations +supervening at a rather late embryonic period, and being inherited at a +corresponding period, how it is that the embryos of wonderfully different +forms should still retain, more or less perfectly, the structure of their +common progenitor. No other explanation has ever been given of the +marvellous fact that the embryos of a man, dog, seal, bat, reptile, etc., +can at first hardly be distinguished from each other. In order to +understand the existence of rudimentary organs, we have only to suppose +that a former progenitor possessed the parts in question in a perfect +state, and that under changed habits of life they became greatly reduced, +either from simple disuse, or through the natural selection of those +individuals which were least encumbered with a superfluous part, aided by +the other means previously indicated. + +Thus we can understand how it has come to pass that man and all other +vertebrate animals have been constructed on the same general model, why +they pass through the same early stages of development, and why they retain +certain rudiments in common. Consequently we ought frankly to admit their +community of descent: to take any other view, is to admit that our own +structure, and that of all the animals around us, is a mere snare laid to +entrap our judgment. This conclusion is greatly strengthened, if we look +to the members of the whole animal series, and consider the evidence +derived from their affinities or classification, their geographical +distribution and geological succession. It is only our natural prejudice, +and that arrogance which made our forefathers declare that they were +descended from demi-gods, which leads us to demur to this conclusion. But +the time will before long come, when it will be thought wonderful that +naturalists, who were well acquainted with the comparative structure and +development of man, and other mammals, should have believed that each was +the work of a separate act of creation. + + +CHAPTER II. + +ON THE MANNER OF DEVELOPMENT OF MAN FROM SOME LOWER FORM. + +Variability of body and mind in man--Inheritance--Causes of variability-- +Laws of variation the same in man as in the lower animals--Direct action of +the conditions of life--Effects of the increased use and disuse of parts-- +Arrested development--Reversion--Correlated variation--Rate of increase-- +Checks to increase--Natural selection--Man the most dominant animal in the +world--Importance of his corporeal structure--The causes which have led to +his becoming erect--Consequent changes of structure--Decrease in size of +the canine teeth--Increased size and altered shape of the skull--Nakedness +--Absence of a tail--Defenceless condition of man. + +It is manifest that man is now subject to much variability. No two +individuals of the same race are quite alike. We may compare millions of +faces, and each will be distinct. There is an equally great amount of +diversity in the proportions and dimensions of the various parts of the +body; the length of the legs being one of the most variable points. (1. +'Investigations in Military and Anthropological Statistics of American +Soldiers,' by B.A. Gould, 1869, p. 256.) Although in some quarters of the +world an elongated skull, and in other quarters a short skull prevails, yet +there is great diversity of shape even within the limits of the same race, +as with the aborigines of America and South Australia--the latter a race +"probably as pure and homogeneous in blood, customs, and language as any in +existence"--and even with the inhabitants of so confined an area as the +Sandwich Islands. (2. With respect to the "Cranial forms of the American +aborigines," see Dr. Aitken Meigs in 'Proc. Acad. Nat. Sci.' Philadelphia, +May 1868. On the Australians, see Huxley, in Lyell's 'Antiquity of Man,' +1863, p. 87. On the Sandwich Islanders, Prof. J. Wyman, 'Observations on +Crania,' Boston, 1868, p. 18.) An eminent dentist assures me that there is +nearly as much diversity in the teeth as in the features. The chief +arteries so frequently run in abnormal courses, that it has been found +useful for surgical purposes to calculate from 1040 corpses how often each +course prevails. (3. 'Anatomy of the Arteries,' by R. Quain. Preface, +vol. i. 1844.) The muscles are eminently variable: thus those of the foot +were found by Prof. Turner (4. 'Transactions of the Royal Society of +Edinburgh,' vol. xxiv. pp. 175, 189.) not to be strictly alike in any two +out of fifty bodies; and in some the deviations were considerable. He +adds, that the power of performing the appropriate movements must have been +modified in accordance with the several deviations. Mr. J. Wood has +recorded (5. 'Proceedings Royal Society,' 1867, p. 544; also 1868, pp. +483, 524. There is a previous paper, 1866, p. 229.) the occurrence of 295 +muscular variations in thirty-six subjects, and in another set of the same +number no less than 558 variations, those occurring on both sides of the +body being only reckoned as one. In the last set, not one body out of the +thirty-six was "found totally wanting in departures from the standard +descriptions of the muscular system given in anatomical text books." A +single body presented the extraordinary number of twenty-five distinct +abnormalities. The same muscle sometimes varies in many ways: thus Prof. +Macalister describes (6. 'Proc. R. Irish Academy,' vol. x. 1868, p. 141.) +no less than twenty distinct variations in the palmaris accessorius. + +The famous old anatomist, Wolff (7. 'Act. Acad. St. Petersburg,' 1778, +part ii. p. 217.), insists that the internal viscera are more variable than +the external parts: Nulla particula est quae non aliter et aliter in aliis +se habeat hominibus. He has even written a treatise on the choice of +typical examples of the viscera for representation. A discussion on the +beau-ideal of the liver, lungs, kidneys, etc., as of the human face divine, +sounds strange in our ears. + +The variability or diversity of the mental faculties in men of the same +race, not to mention the greater differences between the men of distinct +races, is so notorious that not a word need here be said. So it is with +the lower animals. All who have had charge of menageries admit this fact, +and we see it plainly in our dogs and other domestic animals. Brehm +especially insists that each individual monkey of those which he kept tame +in Africa had its own peculiar disposition and temper: he mentions one +baboon remarkable for its high intelligence; and the keepers in the +Zoological Gardens pointed out to me a monkey, belonging to the New World +division, equally remarkable for intelligence. Rengger, also, insists on +the diversity in the various mental characters of the monkeys of the same +species which he kept in Paraguay; and this diversity, as he adds, is +partly innate, and partly the result of the manner in which they have been +treated or educated. (8. Brehm, 'Thierleben,' B. i. ss. 58, 87. Rengger, +'Säugethiere von Paraguay,' s. 57.) + +I have elsewhere (9. 'Variation of Animals and Plants under +Domestication,' vol. ii. chap. xii.) so fully discussed the subject of +Inheritance, that I need here add hardly anything. A greater number of +facts have been collected with respect to the transmission of the most +trifling, as well as of the most important characters in man, than in any +of the lower animals; though the facts are copious enough with respect to +the latter. So in regard to mental qualities, their transmission is +manifest in our dogs, horses, and other domestic animals. Besides special +tastes and habits, general intelligence, courage, bad and good temper, +etc., are certainly transmitted. With man we see similar facts in almost +every family; and we now know, through the admirable labours of Mr. Galton +(10. 'Hereditary Genius: an Inquiry into its Laws and Consequences,' +1869.), that genius which implies a wonderfully complex combination of high +faculties, tends to be inherited; and, on the other hand, it is too certain +that insanity and deteriorated mental powers likewise run in families. + +With respect to the causes of variability, we are in all cases very +ignorant; but we can see that in man as in the lower animals, they stand in +some relation to the conditions to which each species has been exposed, +during several generations. Domesticated animals vary more than those in a +state of nature; and this is apparently due to the diversified and changing +nature of the conditions to which they have been subjected. In this +respect the different races of man resemble domesticated animals, and so do +the individuals of the same race, when inhabiting a very wide area, like +that of America. We see the influence of diversified conditions in the +more civilised nations; for the members belonging to different grades of +rank, and following different occupations, present a greater range of +character than do the members of barbarous nations. But the uniformity of +savages has often been exaggerated, and in some cases can hardly be said to +exist. (11. Mr. Bates remarks ('The Naturalist on the Amazons,' 1863, +vol. ii p. 159), with respect to the Indians of the same South American +tribe, "no two of them were at all similar in the shape of the head; one +man had an oval visage with fine features, and another was quite Mongolian +in breadth and prominence of cheek, spread of nostrils, and obliquity of +eyes.") It is, nevertheless, an error to speak of man, even if we look +only to the conditions to which he has been exposed, as "far more +domesticated" (12. Blumenbach, 'Treatises on Anthropology.' Eng. +translat., 1865, p. 205.) than any other animal. Some savage races, such +as the Australians, are not exposed to more diversified conditions than are +many species which have a wide range. In another and much more important +respect, man differs widely from any strictly domesticated animal; for his +breeding has never long been controlled, either by methodical or +unconscious selection. No race or body of men has been so completely +subjugated by other men, as that certain individuals should be preserved, +and thus unconsciously selected, from somehow excelling in utility to their +masters. Nor have certain male and female individuals been intentionally +picked out and matched, except in the well-known case of the Prussian +grenadiers; and in this case man obeyed, as might have been expected, the +law of methodical selection; for it is asserted that many tall men were +reared in the villages inhabited by the grenadiers and their tall wives. +In Sparta, also, a form of selection was followed, for it was enacted that +all children should be examined shortly after birth; the well-formed and +vigorous being preserved, the others left to perish. (13. Mitford's +'History of Greece,' vol. i. p. 282. It appears also from a passage in +Xenophon's 'Memorabilia,' B. ii. 4 (to which my attention has been called +by the Rev. J.N. Hoare), that it was a well recognised principle with the +Greeks, that men ought to select their wives with a view to the health and +vigour of their children. The Grecian poet, Theognis, who lived 550 B.C., +clearly saw how important selection, if carefully applied, would be for the +improvement of mankind. He saw, likewise, that wealth often checks the +proper action of sexual selection. He thus writes: + + "With kine and horses, Kurnus! we proceed + By reasonable rules, and choose a breed + For profit and increase, at any price: + Of a sound stock, without defect or vice. + But, in the daily matches that we make, + The price is everything: for money's sake, + Men marry: women are in marriage given + The churl or ruffian, that in wealth has thriven, + May match his offspring with the proudest race: + Thus everything is mix'd, noble and base! + If then in outward manner, form, and mind, + You find us a degraded, motley kind, + Wonder no more, my friend! the cause is plain, + And to lament the consequence is vain." + +(The Works of J. Hookham Frere, vol. ii. 1872, p. 334.)) + +If we consider all the races of man as forming a single species, his range +is enormous; but some separate races, as the Americans and Polynesians, +have very wide ranges. It is a well-known law that widely-ranging species +are much more variable than species with restricted ranges; and the +variability of man may with more truth be compared with that of widely- +ranging species, than with that of domesticated animals. + +Not only does variability appear to be induced in man and the lower animals +by the same general causes, but in both the same parts of the body are +affected in a closely analogous manner. This has been proved in such full +detail by Godron and Quatrefages, that I need here only refer to their +works. (14. Godron, 'De l'Espèce,' 1859, tom. ii. livre 3. Quatrefages, +'Unité de l'Espèce Humaine,' 1861. Also Lectures on Anthropology, given in +the 'Revue des Cours Scientifiques,' 1866-1868.) Monstrosities, which +graduate into slight variations, are likewise so similar in man and the +lower animals, that the same classification and the same terms can be used +for both, as has been shewn by Isidore Geoffroy St.-Hilaire. (15. 'Hist. +Gen. et Part. des Anomalies de l'Organisation,' in three volumes, tom. i. +1832.) In my work on the variation of domestic animals, I have attempted +to arrange in a rude fashion the laws of variation under the following +heads:--The direct and definite action of changed conditions, as exhibited +by all or nearly all the individuals of the same species, varying in the +same manner under the same circumstances. The effects of the long- +continued use or disuse of parts. The cohesion of homologous parts. The +variability of multiple parts. Compensation of growth; but of this law I +have found no good instance in the case of man. The effects of the +mechanical pressure of one part on another; as of the pelvis on the cranium +of the infant in the womb. Arrests of development, leading to the +diminution or suppression of parts. The reappearance of long-lost +characters through reversion. And lastly, correlated variation. All these +so-called laws apply equally to man and the lower animals; and most of them +even to plants. It would be superfluous here to discuss all of them (16. +I have fully discussed these laws in my 'Variation of Animals and Plants +under Domestication,' vol. ii. chap. xxii. and xxiii. M. J.P. Durand has +lately (1868) published a valuable essay, 'De l'Influence des Milieux,' +etc. He lays much stress, in the case of plants, on the nature of the +soil.); but several are so important, that they must be treated at +considerable length. + +THE DIRECT AND DEFINITE ACTION OF CHANGED CONDITIONS. + +This is a most perplexing subject. It cannot be denied that changed +conditions produce some, and occasionally a considerable effect, on +organisms of all kinds; and it seems at first probable that if sufficient +time were allowed this would be the invariable result. But I have failed +to obtain clear evidence in favour of this conclusion; and valid reasons +may be urged on the other side, at least as far as the innumerable +structures are concerned, which are adapted for special ends. There can, +however, be no doubt that changed conditions induce an almost indefinite +amount of fluctuating variability, by which the whole organisation is +rendered in some degree plastic. + +In the United States, above 1,000,000 soldiers, who served in the late war, +were measured, and the States in which they were born and reared were +recorded. (17. 'Investigations in Military and Anthrop. Statistics,' +etc., 1869, by B.A. Gould, pp. 93, 107, 126, 131, 134.) From this +astonishing number of observations it is proved that local influences of +some kind act directly on stature; and we further learn that "the State +where the physical growth has in great measure taken place, and the State +of birth, which indicates the ancestry, seem to exert a marked influence on +the stature." For instance, it is established, "that residence in the +Western States, during the years of growth, tends to produce increase of +stature." On the other hand, it is certain that with sailors, their life +delays growth, as shewn "by the great difference between the statures of +soldiers and sailors at the ages of seventeen and eighteen years." Mr. +B.A. Gould endeavoured to ascertain the nature of the influences which thus +act on stature; but he arrived only at negative results, namely that they +did not relate to climate, the elevation of the land, soil, nor even "in +any controlling degree" to the abundance or the need of the comforts of +life. This latter conclusion is directly opposed to that arrived at by +Villerme, from the statistics of the height of the conscripts in different +parts of France. When we compare the differences in stature between the +Polynesian chiefs and the lower orders within the same islands, or between +the inhabitants of the fertile volcanic and low barren coral islands of the +same ocean (18. For the Polynesians, see Prichard's 'Physical History of +Mankind,' vol. v. 1847, pp. 145, 283. Also Godron, 'De l'Espèce,' tom. ii. +p. 289. There is also a remarkable difference in appearance between the +closely-allied Hindoos inhabiting the Upper Ganges and Bengal; see +Elphinstone's 'History of India,' vol. i. p. 324.) or again between the +Fuegians on the eastern and western shores of their country, where the +means of subsistence are very different, it is scarcely possible to avoid +the conclusion that better food and greater comfort do influence stature. +But the preceding statements shew how difficult it is to arrive at any +precise result. Dr. Beddoe has lately proved that, with the inhabitants of +Britain, residence in towns and certain occupations have a deteriorating +influence on height; and he infers that the result is to a certain extent +inherited, as is likewise the case in the United States. Dr. Beddoe +further believes that wherever a "race attains its maximum of physical +development, it rises highest in energy and moral vigour." (19. 'Memoirs, +Anthropological Society,' vol. iii. 1867-69, pp. 561, 565, 567.) + +Whether external conditions produce any other direct effect on man is not +known. It might have been expected that differences of climate would have +had a marked influence, inasmuch as the lungs and kidneys are brought into +activity under a low temperature, and the liver and skin under a high one. +(20. Dr. Brakenridge, 'Theory of Diathesis,' 'Medical Times,' June 19 and +July 17, 1869.) It was formerly thought that the colour of the skin and +the character of the hair were determined by light or heat; and although it +can hardly be denied that some effect is thus produced, almost all +observers now agree that the effect has been very small, even after +exposure during many ages. But this subject will be more properly +discussed when we treat of the different races of mankind. With our +domestic animals there are grounds for believing that cold and damp +directly affect the growth of the hair; but I have not met with any +evidence on this head in the case of man. + +EFFECTS OF THE INCREASED USE AND DISUSE OF PARTS. + +It is well known that use strengthens the muscles in the individual, and +complete disuse, or the destruction of the proper nerve, weakens them. +When the eye is destroyed, the optic nerve often becomes atrophied. When +an artery is tied, the lateral channels increase not only in diameter, but +in the thickness and strength of their coats. When one kidney ceases to +act from disease, the other increases in size, and does double work. Bones +increase not only in thickness, but in length, from carrying a greater +weight. (21. I have given authorities for these several statements in my +'Variation of Animals and Plants under Domestication,' vol. ii. pp. 297- +300. Dr. Jaeger, "Über das Langenwachsthum der Knochen," 'Jenäischen +Zeitschrift,' B. v. Heft. i.) Different occupations, habitually followed, +lead to changed proportions in various parts of the body. Thus it was +ascertained by the United States Commission (22. 'Investigations,' etc., +by B.A. Gould, 1869, p. 288.) that the legs of the sailors employed in the +late war were longer by 0.217 of an inch than those of the soldiers, though +the sailors were on an average shorter men; whilst their arms were shorter +by 1.09 of an inch, and therefore, out of proportion, shorter in relation +to their lesser height. This shortness of the arms is apparently due to +their greater use, and is an unexpected result: but sailors chiefly use +their arms in pulling, and not in supporting weights. With sailors, the +girth of the neck and the depth of the instep are greater, whilst the +circumference of the chest, waist, and hips is less, than in soldiers. + +Whether the several foregoing modifications would become hereditary, if the +same habits of life were followed during many generations, is not known, +but it is probable. Rengger (23. 'Säugethiere von Paraguay,' 1830, s. 4.) +attributes the thin legs and thick arms of the Payaguas Indians to +successive generations having passed nearly their whole lives in canoes, +with their lower extremities motionless. Other writers have come to a +similar conclusion in analogous cases. According to Cranz (24. 'History +of Greenland,' Eng. translat., 1767, vol. i. p. 230.), who lived for a long +time with the Esquimaux, "the natives believe that ingenuity and dexterity +in seal-catching (their highest art and virtue) is hereditary; there is +really something in it, for the son of a celebrated seal-catcher will +distinguish himself, though he lost his father in childhood." But in this +case it is mental aptitude, quite as much as bodily structure, which +appears to be inherited. It is asserted that the hands of English +labourers are at birth larger than those of the gentry. (25. +'Intermarriage,' by Alex. Walker, 1838, p. 377.) From the correlation +which exists, at least in some cases (26. 'The Variation of Animals under +Domestication,' vol. i. p. 173.), between the development of the +extremities and of the jaws, it is possible that in those classes which do +not labour much with their hands and feet, the jaws would be reduced in +size from this cause. That they are generally smaller in refined and +civilised men than in hard-working men or savages, is certain. But with +savages, as Mr. Herbert Spencer (27. 'Principles of Biology,' vol. i. p. +455.) has remarked, the greater use of the jaws in chewing coarse, uncooked +food, would act in a direct manner on the masticatory muscles, and on the +bones to which they are attached. In infants, long before birth, the skin +on the soles of the feet is thicker than on any other part of the body; +(28. Paget, 'Lectures on Surgical Pathology,' vol. ii, 1853, p. 209.) and +it can hardly be doubted that this is due to the inherited effects of +pressure during a long series of generations. + +It is familiar to every one that watchmakers and engravers are liable to be +short-sighted, whilst men living much out of doors, and especially savages, +are generally long-sighted. (29. It is a singular and unexpected fact +that sailors are inferior to landsmen in their mean distance of distinct +vision. Dr. B.A. Gould ('Sanitary Memoirs of the War of the Rebellion,' +1869, p. 530), has proved this to be the case; and he accounts for it by +the ordinary range of vision in sailors being "restricted to the length of +the vessel and the height of the masts.") Short-sight and long-sight +certainly tend to be inherited. (30. 'The Variation of Animals under +Domestication,' vol. i. p. 8.) The inferiority of Europeans, in comparison +with savages, in eyesight and in the other senses, is no doubt the +accumulated and transmitted effect of lessened use during many generations; +for Rengger (31. 'Säugethiere von Paraguay,' s. 8, 10. I have had good +opportunities for observing the extraordinary power of eyesight in the +Fuegians. See also Lawrence ('Lectures on Physiology,' etc., 1822, p. 404) +on this same subject. M. Giraud-Teulon has recently collected ('Revue des +Cours Scientifiques,' 1870, p. 625) a large and valuable body of evidence +proving that the cause of short-sight, "C'est le travail assidu, de près.") +states that he has repeatedly observed Europeans, who had been brought up +and spent their whole lives with the wild Indians, who nevertheless did not +equal them in the sharpness of their senses. The same naturalist observes +that the cavities in the skull for the reception of the several sense- +organs are larger in the American aborigines than in Europeans; and this +probably indicates a corresponding difference in the dimensions of the +organs themselves. Blumenbach has also remarked on the large size of the +nasal cavities in the skulls of the American aborigines, and connects this +fact with their remarkably acute power of smell. The Mongolians of the +plains of northern Asia, according to Pallas, have wonderfully perfect +senses; and Prichard believes that the great breadth of their skulls across +the zygomas follows from their highly-developed sense organs. (32. +Prichard, 'Physical History of Mankind,' on the authority of Blumenbach, +vol. i. 1851, p. 311; for the statement by Pallas, vol. iv. 1844, p. 407.) + +The Quechua Indians inhabit the lofty plateaux of Peru; and Alcide +d'Orbigny states (33. Quoted by Prichard, 'Researches into the Physical +History of Mankind,' vol. v. p. 463.) that, from continually breathing a +highly rarefied atmosphere, they have acquired chests and lungs of +extraordinary dimensions. The cells, also, of the lungs are larger and +more numerous than in Europeans. These observations have been doubted, but +Mr. D. Forbes carefully measured many Aymaras, an allied race, living at +the height of between 10,000 and 15,000 feet; and he informs me (34. Mr. +Forbes' valuable paper is now published in the 'Journal of the Ethnological +Society of London,' new series, vol. ii. 1870, p.193.) that they differ +conspicuously from the men of all other races seen by him in the +circumference and length of their bodies. In his table of measurements, +the stature of each man is taken at 1000, and the other measurements are +reduced to this standard. It is here seen that the extended arms of the +Aymaras are shorter than those of Europeans, and much shorter than those of +Negroes. The legs are likewise shorter; and they present this remarkable +peculiarity, that in every Aymara measured, the femur is actually shorter +than the tibia. On an average, the length of the femur to that of the +tibia is as 211 to 252; whilst in two Europeans, measured at the same time, +the femora to the tibiae were as 244 to 230; and in three Negroes as 258 to +241. The humerus is likewise shorter relatively to the forearm. This +shortening of that part of the limb which is nearest to the body, appears +to be, as suggested to me by Mr. Forbes, a case of compensation in relation +with the greatly increased length of the trunk. The Aymaras present some +other singular points of structure, for instance, the very small projection +of the heel. + +These men are so thoroughly acclimatised to their cold and lofty abode, +that when formerly carried down by the Spaniards to the low eastern plains, +and when now tempted down by high wages to the gold-washings, they suffer a +frightful rate of mortality. Nevertheless Mr. Forbes found a few pure +families which had survived during two generations: and he observed that +they still inherited their characteristic peculiarities. But it was +manifest, even without measurement, that these peculiarities had all +decreased; and on measurement, their bodies were found not to be so much +elongated as those of the men on the high plateau; whilst their femora had +become somewhat lengthened, as had their tibiae, although in a less degree. +The actual measurements may be seen by consulting Mr. Forbes's memoir. +From these observations, there can, I think, be no doubt that residence +during many generations at a great elevation tends, both directly and +indirectly, to induce inherited modifications in the proportions of the +body. (35. Dr. Wilckens ('Landwirthschaft. Wochenblatt,' No. 10, 1869) +has lately published an interesting essay shewing how domestic animals, +which live in mountainous regions, have their frames modified.) + +Although man may not have been much modified during the latter stages of +his existence through the increased or decreased use of parts, the facts +now given shew that his liability in this respect has not been lost; and we +positively know that the same law holds good with the lower animals. +Consequently we may infer that when at a remote epoch the progenitors of +man were in a transitional state, and were changing from quadrupeds into +bipeds, natural selection would probably have been greatly aided by the +inherited effects of the increased or diminished use of the different parts +of the body. + +ARRESTS OF DEVELOPMENT. + +There is a difference between arrested development and arrested growth, for +parts in the former state continue to grow whilst still retaining their +early condition. Various monstrosities come under this head; and some, as +a cleft palate, are known to be occasionally inherited. It will suffice +for our purpose to refer to the arrested brain-development of +microcephalous idiots, as described in Vogt's memoir. (36. 'Mémoire sur +les Microcephales,' 1867, pp. 50, 125, 169, 171, 184-198.) Their skulls +are smaller, and the convolutions of the brain are less complex than in +normal men. The frontal sinus, or the projection over the eye-brows, is +largely developed, and the jaws are prognathous to an "effrayant" degree; +so that these idiots somewhat resemble the lower types of mankind. Their +intelligence, and most of their mental faculties, are extremely feeble. +They cannot acquire the power of speech, and are wholly incapable of +prolonged attention, but are much given to imitation. They are strong and +remarkably active, continually gambolling and jumping about, and making +grimaces. They often ascend stairs on all-fours; and are curiously fond of +climbing up furniture or trees. We are thus reminded of the delight shewn +by almost all boys in climbing trees; and this again reminds us how lambs +and kids, originally alpine animals, delight to frisk on any hillock, +however small. Idiots also resemble the lower animals in some other +respects; thus several cases are recorded of their carefully smelling every +mouthful of food before eating it. One idiot is described as often using +his mouth in aid of his hands, whilst hunting for lice. They are often +filthy in their habits, and have no sense of decency; and several cases +have been published of their bodies being remarkably hairy. (37. Prof. +Laycock sums up the character of brute-like idiots by calling them +"theroid;" 'Journal of Mental Science,' July 1863. Dr. Scott ('The Deaf +and Dumb,' 2nd ed. 1870, p. 10) has often observed the imbecile smelling +their food. See, on this same subject, and on the hairiness of idiots, Dr. +Maudsley, 'Body and Mind,' 1870, pp. 46-51. Pinel has also given a +striking case of hairiness in an idiot.) + +REVERSION. + +Many of the cases to be here given, might have been introduced under the +last heading. When a structure is arrested in its development, but still +continues growing, until it closely resembles a corresponding structure in +some lower and adult member of the same group, it may in one sense be +considered as a case of reversion. The lower members in a group give us +some idea how the common progenitor was probably constructed; and it is +hardly credible that a complex part, arrested at an early phase of +embryonic development, should go on growing so as ultimately to perform its +proper function, unless it had acquired such power during some earlier +state of existence, when the present exceptional or arrested structure was +normal. The simple brain of a microcephalous idiot, in as far as it +resembles that of an ape, may in this sense be said to offer a case of +reversion. (38. In my 'Variation of Animals under Domestication' (vol. +ii. p. 57), I attributed the not very rare cases of supernumerary mammae in +women to reversion. I was led to this as a probable conclusion, by the +additional mammae being generally placed symmetrically on the breast; and +more especially from one case, in which a single efficient mamma occurred +in the inguinal region of a woman, the daughter of another woman with +supernumerary mammae. But I now find (see, for instance, Prof. Preyer, +'Der Kampf um das Dasein,' 1869, s. 45) that mammae erraticae, occur in +other situations, as on the back, in the armpit, and on the thigh; the +mammae in this latter instance having given so much milk that the child was +thus nourished. The probability that the additional mammae are due to +reversion is thus much weakened; nevertheless, it still seems to me +probable, because two pairs are often found symmetrically on the breast; +and of this I myself have received information in several cases. It is +well known that some Lemurs normally have two pairs of mammae on the +breast. Five cases have been recorded of the presence of more than a pair +of mammae (of course rudimentary) in the male sex of mankind; see 'Journal +of Anat. and Physiology,' 1872, p. 56, for a case given by Dr. Handyside, +in which two brothers exhibited this peculiarity; see also a paper by Dr. +Bartels, in 'Reichert's and du Bois-Reymond's Archiv.,' 1872, p. 304. In +one of the cases alluded to by Dr. Bartels, a man bore five mammae, one +being medial and placed above the navel; Meckel von Hemsbach thinks that +this latter case is illustrated by a medial mamma occurring in certain +Cheiroptera. On the whole, we may well doubt if additional mammae would +ever have been developed in both sexes of mankind, had not his early +progenitors been provided with more than a single pair. + +In the above work (vol. ii. p. 12), I also attributed, though with much +hesitation, the frequent cases of polydactylism in men and various animals +to reversion. I was partly led to this through Prof. Owen's statement, +that some of the Ichthyopterygia possess more than five digits, and +therefore, as I supposed, had retained a primordial condition; but Prof. +Gegenbaur ('Jenaischen Zeitschrift,' B. v. Heft 3, s. 341), disputes Owen's +conclusion. On the other hand, according to the opinion lately advanced by +Dr. Gunther, on the paddle of Ceratodus, which is provided with articulated +bony rays on both sides of a central chain of bones, there seems no great +difficulty in admitting that six or more digits on one side, or on both +sides, might reappear through reversion. I am informed by Dr. Zouteveen +that there is a case on record of a man having twenty-four fingers and +twenty-four toes! I was chiefly led to the conclusion that the presence of +supernumerary digits might be due to reversion from the fact that such +digits, not only are strongly inherited, but, as I then believed, had the +power of regrowth after amputation, like the normal digits of the lower +vertebrata. But I have explained in the second edition of my Variation +under Domestication why I now place little reliance on the recorded cases +of such regrowth. Nevertheless it deserves notice, inasmuch as arrested +development and reversion are intimately related processes; that various +structures in an embryonic or arrested condition, such as a cleft palate, +bifid uterus, etc., are frequently accompanied by polydactylism. This has +been strongly insisted on by Meckel and Isidore Geoffroy St.-Hilaire. But +at present it is the safest course to give up altogether the idea that +there is any relation between the development of supernumerary digits and +reversion to some lowly organised progenitor of man.) There are other +cases which come more strictly under our present head of reversion. +Certain structures, regularly occurring in the lower members of the group +to which man belongs, occasionally make their appearance in him, though not +found in the normal human embryo; or, if normally present in the human +embryo, they become abnormally developed, although in a manner which is +normal in the lower members of the group. These remarks will be rendered +clearer by the following illustrations. + +In various mammals the uterus graduates from a double organ with two +distinct orifices and two passages, as in the marsupials, into a single +organ, which is in no way double except from having a slight internal fold, +as in the higher apes and man. The rodents exhibit a perfect series of +gradations between these two extreme states. In all mammals the uterus is +developed from two simple primitive tubes, the inferior portions of which +form the cornua; and it is in the words of Dr. Farre, "by the coalescence +of the two cornua at their lower extremities that the body of the uterus is +formed in man; while in those animals in which no middle portion or body +exists, the cornua remain ununited. As the development of the uterus +proceeds, the two cornua become gradually shorter, until at length they are +lost, or, as it were, absorbed into the body of the uterus." The angles of +the uterus are still produced into cornua, even in animals as high up in +the scale as the lower apes and lemurs. + +Now in women, anomalous cases are not very infrequent, in which the mature +uterus is furnished with cornua, or is partially divided into two organs; +and such cases, according to Owen, repeat "the grade of concentrative +development," attained by certain rodents. Here perhaps we have an +instance of a simple arrest of embryonic development, with subsequent +growth and perfect functional development; for either side of the partially +double uterus is capable of performing the proper office of gestation. In +other and rarer cases, two distinct uterine cavities are formed, each +having its proper orifice and passage. (39. See Dr. A. Farre's well-known +article in the 'Cyclopaedia of Anatomy and Physiology,' vol. v. 1859, p. +642. Owen, 'Anatomy of Vertebrates,' vol. iii. 1868, p. 687. Professor +Turner, in 'Edinburgh Medical Journal,' February, 1865.) No such stage is +passed through during the ordinary development of the embryo; and it is +difficult to believe, though perhaps not impossible, that the two simple, +minute, primitive tubes should know how (if such an expression may be used) +to grow into two distinct uteri, each with a well-constructed orifice and +passage, and each furnished with numerous muscles, nerves, glands and +vessels, if they had not formerly passed through a similar course of +development, as in the case of existing marsupials. No one will pretend +that so perfect a structure as the abnormal double uterus in woman could be +the result of mere chance. But the principle of reversion, by which a +long-lost structure is called back into existence, might serve as the guide +for its full development, even after the lapse of an enormous interval of +time. + +Professor Canestrini, after discussing the foregoing and various analogous +cases, arrives at the same conclusion as that just given. He adduces +another instance, in the case of the malar bone (40. 'Annuario della Soc. +dei Naturalisti,' Modena, 1867, p. 83. Prof. Canestrini gives extracts on +this subject from various authorities. Laurillard remarks, that as he has +found a complete similarity in the form, proportions, and connection of the +two malar bones in several human subjects and in certain apes, he cannot +consider this disposition of the parts as simply accidental. Another paper +on this same anomaly has been published by Dr. Saviotti in the 'Gazzetta +delle Cliniche,' Turin, 1871, where he says that traces of the division may +be detected in about two per cent. of adult skulls; he also remarks that it +more frequently occurs in prognathous skulls, not of the Aryan race, than +in others. See also G. Delorenzi on the same subject; 'Tre nuovi casi +d'anomalia dell' osso malare,' Torino, 1872. Also, E. Morselli, 'Sopra una +rara anomalia dell' osso malare,' Modena, 1872. Still more recently Gruber +has written a pamphlet on the division of this bone. I give these +references because a reviewer, without any grounds or scruples, has thrown +doubts on my statements.), which, in some of the Quadrumana and other +mammals, normally consists of two portions. This is its condition in the +human foetus when two months old; and through arrested development, it +sometimes remains thus in man when adult, more especially in the lower +prognathous races. Hence Canestrini concludes that some ancient progenitor +of man must have had this bone normally divided into two portions, which +afterwards became fused together. In man the frontal bone consists of a +single piece, but in the embryo, and in children, and in almost all the +lower mammals, it consists of two pieces separated by a distinct suture. +This suture occasionally persists more or less distinctly in man after +maturity; and more frequently in ancient than in recent crania, especially, +as Canestrini has observed, in those exhumed from the Drift, and belonging +to the brachycephalic type. Here again he comes to the same conclusion as +in the analogous case of the malar bones. In this, and other instances +presently to be given, the cause of ancient races approaching the lower +animals in certain characters more frequently than do the modern races, +appears to be, that the latter stand at a somewhat greater distance in the +long line of descent from their early semi-human progenitors. + +Various other anomalies in man, more or less analogous to the foregoing, +have been advanced by different authors, as cases of reversion; but these +seem not a little doubtful, for we have to descend extremely low in the +mammalian series, before we find such structures normally present. (41. A +whole series of cases is given by Isidore Geoffroy St.-Hilaire, 'Hist. des +Anomalies,' tom, iii, p. 437. A reviewer ('Journal of Anatomy and +Physiology,' 1871, p. 366) blames me much for not having discussed the +numerous cases, which have been recorded, of various parts arrested in +their development. He says that, according to my theory, "every transient +condition of an organ, during its development, is not only a means to an +end, but once was an end in itself." This does not seem to me necessarily +to hold good. Why should not variations occur during an early period of +development, having no relation to reversion; yet such variations might be +preserved and accumulated, if in any way serviceable, for instance, in +shortening and simplifying the course of development? And again, why +should not injurious abnormalities, such as atrophied or hypertrophied +parts, which have no relation to a former state of existence, occur at an +early period, as well as during maturity?) + +In man, the canine teeth are perfectly efficient instruments for +mastication. But their true canine character, as Owen (42. 'Anatomy of +Vertebrates,' vol. iii. 1868, p. 323.) remarks, "is indicated by the +conical form of the crown, which terminates in an obtuse point, is convex +outward and flat or sub-concave within, at the base of which surface there +is a feeble prominence. The conical form is best expressed in the Melanian +races, especially the Australian. The canine is more deeply implanted, and +by a stronger fang than the incisors." Nevertheless, this tooth no longer +serves man as a special weapon for tearing his enemies or prey; it may, +therefore, as far as its proper function is concerned, be considered as +rudimentary. In every large collection of human skulls some may be found, +as Haeckel (43. 'Generelle Morphologie,' 1866, B. ii. s. clv.) observes, +with the canine teeth projecting considerably beyond the others in the same +manner as in the anthropomorphous apes, but in a less degree. In these +cases, open spaces between the teeth in the one jaw are left for the +reception of the canines of the opposite jaw. An inter-space of this kind +in a Kaffir skull, figured by Wagner, is surprisingly wide. (44. Carl +Vogt's 'Lectures on Man,' Eng. translat., 1864, p. 151.) Considering how +few are the ancient skulls which have been examined, compared to recent +skulls, it is an interesting fact that in at least three cases the canines +project largely; and in the Naulette jaw they are spoken of as enormous. +(45. C. Carter Blake, on a jaw from La Naulette, 'Anthropological Review,' +1867, p. 295. Schaaffhausen, ibid. 1868, p. 426.) + +Of the anthropomorphous apes the males alone have their canines fully +developed; but in the female gorilla, and in a less degree in the female +orang, these teeth project considerably beyond the others; therefore the +fact, of which I have been assured, that women sometimes have considerably +projecting canines, is no serious objection to the belief that their +occasional great development in man is a case of reversion to an ape-like +progenitor. He who rejects with scorn the belief that the shape of his own +canines, and their occasional great development in other men, are due to +our early forefathers having been provided with these formidable weapons, +will probably reveal, by sneering, the line of his descent. For though he +no longer intends, nor has the power, to use these teeth as weapons, he +will unconsciously retract his "snarling muscles" (thus named by Sir C. +Bell) (46. The Anatomy of Expression, 1844, pp. 110, 131.), so as to +expose them ready for action, like a dog prepared to fight. + +Many muscles are occasionally developed in man, which are proper to the +Quadrumana or other mammals. Professor Vlacovich (47. Quoted by Prof. +Canestrini in the 'Annuario della Soc. dei Naturalisti,' 1867, p. 90.) +examined forty male subjects, and found a muscle, called by him the ischio- +pubic, in nineteen of them; in three others there was a ligament which +represented this muscle; and in the remaining eighteen no trace of it. In +only two out of thirty female subjects was this muscle developed on both +sides, but in three others the rudimentary ligament was present. This +muscle, therefore, appears to be much more common in the male than in the +female sex; and on the belief in the descent of man from some lower form, +the fact is intelligible; for it has been detected in several of the lower +animals, and in all of these it serves exclusively to aid the male in the +act of reproduction. + +Mr. J. Wood, in his valuable series of papers (48. These papers deserve +careful study by any one who desires to learn how frequently our muscles +vary, and in varying come to resemble those of the Quadrumana. The +following references relate to the few points touched on in my text: +'Proc. Royal Soc.' vol. xiv. 1865, pp. 379-384; vol. xv. 1866, pp. 241, +242; vol. xv. 1867, p. 544; vol. xvi. 1868, p. 524. I may here add that +Dr. Murie and Mr. St. George Mivart have shewn in their Memoir on the +Lemuroidea ('Transactions, Zoological Society,' vol. vii. 1869, p. 96), how +extraordinarily variable some of the muscles are in these animals, the +lowest members of the Primates. Gradations, also, in the muscles leading +to structures found in animals still lower in the scale, are numerous in +the Lemuroidea.), has minutely described a vast number of muscular +variations in man, which resemble normal structures in the lower animals. +The muscles which closely resemble those regularly present in our nearest +allies, the Quadrumana, are too numerous to be here even specified. In a +single male subject, having a strong bodily frame, and well-formed skull, +no less than seven muscular variations were observed, all of which plainly +represented muscles proper to various kinds of apes. This man, for +instance, had on both sides of his neck a true and powerful "levator +claviculae," such as is found in all kinds of apes, and which is said to +occur in about one out of sixty human subjects. (49. See also Prof. +Macalister in 'Proceedings, Royal Irish Academy,' vol. x. 1868, p. 124.) +Again, this man had "a special abductor of the metatarsal bone of the fifth +digit, such as Professor Huxley and Mr. Flower have shewn to exist +uniformly in the higher and lower apes." I will give only two additional +cases; the acromio-basilar muscle is found in all mammals below man, and +seems to be correlated with a quadrupedal gait, (50. Mr. Champneys in +'Journal of Anatomy and Physiology,' Nov. 1871, p. 178.) and it occurs in +about one out of sixty human subjects. In the lower extremities Mr. +Bradley (51. Ibid. May 1872, p. 421.) found an abductor ossis metatarsi +quinti in both feet of man; this muscle had not up to that time been +recorded in mankind, but is always present in the anthropomorphous apes. +The muscles of the hands and arms--parts which are so eminently +characteristic of man--are extremely liable to vary, so as to resemble the +corresponding muscles in the lower animals. (52. Prof. Macalister (ibid. +p. 121) has tabulated his observations, and finds that muscular +abnormalities are most frequent in the fore-arms, secondly, in the face, +thirdly, in the foot, etc.) Such resemblances are either perfect or +imperfect; yet in the latter case they are manifestly of a transitional +nature. Certain variations are more common in man, and others in woman, +without our being able to assign any reason. Mr. Wood, after describing +numerous variations, makes the following pregnant remark. "Notable +departures from the ordinary type of the muscular structures run in grooves +or directions, which must be taken to indicate some unknown factor, of much +importance to a comprehensive knowledge of general and scientific anatomy." +(53. The Rev. Dr. Haughton, after giving ('Proc. R. Irish Academy,' June +27, 1864, p. 715) a remarkable case of variation in the human flexor +pollicis longus, adds, "This remarkable example shews that man may +sometimes possess the arrangement of tendons of thumb and fingers +characteristic of the macaque; but whether such a case should be regarded +as a macaque passing upwards into a man, or a man passing downwards into a +macaque, or as a congenital freak of nature, I cannot undertake to say." +It is satisfactory to hear so capable an anatomist, and so embittered an +opponent of evolutionism, admitting even the possibility of either of his +first propositions. Prof. Macalister has also described ('Proceedings +Royal Irish Academy,' vol. x. 1864, p. 138) variations in the flexor +pollicis longus, remarkable from their relations to the same muscle in the +Quadrumana.) + +That this unknown factor is reversion to a former state of existence may be +admitted as in the highest degree probable. (54. Since the first edition +of this book appeared, Mr. Wood has published another memoir in the +Philosophical Transactions, 1870, p. 83, on the varieties of the muscles of +the human neck, shoulder, and chest. He here shews how extremely variable +these muscles are, and how often and how closely the variations resemble +the normal muscles of the lower animals. He sums up by remarking, "It will +be enough for my purpose if I have succeeded in shewing the more important +forms which, when occurring as varieties in the human subject, tend to +exhibit in a sufficiently marked manner what may be considered as proofs +and examples of the Darwinian principle of reversion, or law of +inheritance, in this department of anatomical science.") It is quite +incredible that a man should through mere accident abnormally resemble +certain apes in no less than seven of his muscles, if there had been no +genetic connection between them. On the other hand, if man is descended +from some ape-like creature, no valid reason can be assigned why certain +muscles should not suddenly reappear after an interval of many thousand +generations, in the same manner as with horses, asses, and mules, dark- +coloured stripes suddenly reappear on the legs, and shoulders, after an +interval of hundreds, or more probably of thousands of generations. + +These various cases of reversion are so closely related to those of +rudimentary organs given in the first chapter, that many of them might have +been indifferently introduced either there or here. Thus a human uterus +furnished with cornua may be said to represent, in a rudimentary condition, +the same organ in its normal state in certain mammals. Some parts which +are rudimentary in man, as the os coccyx in both sexes, and the mammae in +the male sex, are always present; whilst others, such as the supracondyloid +foramen, only occasionally appear, and therefore might have been introduced +under the head of reversion. These several reversionary structures, as +well as the strictly rudimentary ones, reveal the descent of man from some +lower form in an unmistakable manner. + +CORRELATED VARIATION. + +In man, as in the lower animals, many structures are so intimately related, +that when one part varies so does another, without our being able, in most +cases, to assign any reason. We cannot say whether the one part governs +the other, or whether both are governed by some earlier developed part. +Various monstrosities, as I. Geoffroy repeatedly insists, are thus +intimately connected. Homologous structures are particularly liable to +change together, as we see on the opposite sides of the body, and in the +upper and lower extremities. Meckel long ago remarked, that when the +muscles of the arm depart from their proper type, they almost always +imitate those of the leg; and so, conversely, with the muscles of the legs. +The organs of sight and hearing, the teeth and hair, the colour of the skin +and of the hair, colour and constitution, are more or less correlated. +(55. The authorities for these several statements are given in my +'Variation of Animals under Domestication,' vol. ii. pp. 320-335.) +Professor Schaaffhausen first drew attention to the relation apparently +existing between a muscular frame and the strongly-pronounced supra-orbital +ridges, which are so characteristic of the lower races of man. + +Besides the variations which can be grouped with more or less probability +under the foregoing heads, there is a large class of variations which may +be provisionally called spontaneous, for to our ignorance they appear to +arise without any exciting cause. It can, however, be shewn that such +variations, whether consisting of slight individual differences, or of +strongly-marked and abrupt deviations of structure, depend much more on the +constitution of the organism than on the nature of the conditions to which +it has been subjected. (56. This whole subject has been discussed in +chap. xxiii. vol. ii. of my 'Variation of Animals and Plants under +Domestication.') + +RATE OF INCREASE. + +Civilised populations have been known under favourable conditions, as in +the United States, to double their numbers in twenty-five years; and, +according to a calculation, by Euler, this might occur in a little over +twelve years. (57. See the ever memorable 'Essay on the Principle of +Population,' by the Rev. T. Malthus, vol. i. 1826. pp. 6, 517.) At the +former rate, the present population of the United States (thirty millions), +would in 657 years cover the whole terraqueous globe so thickly, that four +men would have to stand on each square yard of surface. The primary or +fundamental check to the continued increase of man is the difficulty of +gaining subsistence, and of living in comfort. We may infer that this is +the case from what we see, for instance, in the United States, where +subsistence is easy, and there is plenty of room. If such means were +suddenly doubled in Great Britain, our number would be quickly doubled. +With civilised nations this primary check acts chiefly by restraining +marriages. The greater death-rate of infants in the poorest classes is +also very important; as well as the greater mortality, from various +diseases, of the inhabitants of crowded and miserable houses, at all ages. +The effects of severe epidemics and wars are soon counterbalanced, and more +than counterbalanced, in nations placed under favourable conditions. +Emigration also comes in aid as a temporary check, but, with the extremely +poor classes, not to any great extent. + +There is reason to suspect, as Malthus has remarked, that the reproductive +power is actually less in barbarous, than in civilised races. We know +nothing positively on this head, for with savages no census has been taken; +but from the concurrent testimony of missionaries, and of others who have +long resided with such people, it appears that their families are usually +small, and large ones rare. This may be partly accounted for, as it is +believed, by the women suckling their infants during a long time; but it is +highly probable that savages, who often suffer much hardship, and who do +not obtain so much nutritious food as civilised men, would be actually less +prolific. I have shewn in a former work (58. 'Variation of Animals and +Plants under Domestication,' vol ii. pp. 111-113, 163.), that all our +domesticated quadrupeds and birds, and all our cultivated plants, are more +fertile than the corresponding species in a state of nature. It is no +valid objection to this conclusion that animals suddenly supplied with an +excess of food, or when grown very fat; and that most plants on sudden +removal from very poor to very rich soil, are rendered more or less +sterile. We might, therefore, expect that civilised men, who in one sense +are highly domesticated, would be more prolific than wild men. It is also +probable that the increased fertility of civilised nations would become, as +with our domestic animals, an inherited character: it is at least known +that with mankind a tendency to produce twins runs in families. (59. Mr. +Sedgwick, 'British and Foreign Medico-Chirurgical Review,' July 1863, p. +170.) + +Notwithstanding that savages appear to be less prolific than civilised +people, they would no doubt rapidly increase if their numbers were not by +some means rigidly kept down. The Santali, or hill-tribes of India, have +recently afforded a good illustration of this fact; for, as shewn by Mr. +Hunter (60. 'The Annals of Rural Bengal,' by W.W. Hunter, 1868, p. 259.), +they have increased at an extraordinary rate since vaccination has been +introduced, other pestilences mitigated, and war sternly repressed. This +increase, however, would not have been possible had not these rude people +spread into the adjoining districts, and worked for hire. Savages almost +always marry; yet there is some prudential restraint, for they do not +commonly marry at the earliest possible age. The young men are often +required to shew that they can support a wife; and they generally have +first to earn the price with which to purchase her from her parents. With +savages the difficulty of obtaining subsistence occasionally limits their +number in a much more direct manner than with civilised people, for all +tribes periodically suffer from severe famines. At such times savages are +forced to devour much bad food, and their health can hardly fail to be +injured. Many accounts have been published of their protruding stomachs +and emaciated limbs after and during famines. They are then, also, +compelled to wander much, and, as I was assured in Australia, their infants +perish in large numbers. As famines are periodical, depending chiefly on +extreme seasons, all tribes must fluctuate in number. They cannot steadily +and regularly increase, as there is no artificial increase in the supply of +food. Savages, when hard pressed, encroach on each other's territories, +and war is the result; but they are indeed almost always at war with their +neighbours. They are liable to many accidents on land and water in their +search for food; and in some countries they suffer much from the larger +beasts of prey. Even in India, districts have been depopulated by the +ravages of tigers. + +Malthus has discussed these several checks, but he does not lay stress +enough on what is probably the most important of all, namely infanticide, +especially of female infants, and the habit of procuring abortion. These +practices now prevail in many quarters of the world; and infanticide seems +formerly to have prevailed, as Mr. M'Lennan (61. 'Primitive Marriage,' +1865.) has shewn, on a still more extensive scale. These practices appear +to have originated in savages recognising the difficulty, or rather the +impossibility of supporting all the infants that are born. Licentiousness +may also be added to the foregoing checks; but this does not follow from +failing means of subsistence; though there is reason to believe that in +some cases (as in Japan) it has been intentionally encouraged as a means of +keeping down the population. + +If we look back to an extremely remote epoch, before man had arrived at the +dignity of manhood, he would have been guided more by instinct and less by +reason than are the lowest savages at the present time. Our early semi- +human progenitors would not have practised infanticide or polyandry; for +the instincts of the lower animals are never so perverted (62. A writer in +the 'Spectator' (March 12, 1871, p. 320) comments as follows on this +passage:--"Mr. Darwin finds himself compelled to reintroduce a new doctrine +of the fall of man. He shews that the instincts of the higher animals are +far nobler than the habits of savage races of men, and he finds himself, +therefore, compelled to re-introduce,--in a form of the substantial +orthodoxy of which he appears to be quite unconscious,--and to introduce as +a scientific hypothesis the doctrine that man's gain of KNOWLEDGE was the +cause of a temporary but long-enduring moral deterioration as indicated by +the many foul customs, especially as to marriage, of savage tribes. What +does the Jewish tradition of the moral degeneration of man through his +snatching at a knowledge forbidden him by his highest instinct assert +beyond this?") as to lead them regularly to destroy their own offspring, or +to be quite devoid of jealousy. There would have been no prudential +restraint from marriage, and the sexes would have freely united at an early +age. Hence the progenitors of man would have tended to increase rapidly; +but checks of some kind, either periodical or constant, must have kept down +their numbers, even more severely than with existing savages. What the +precise nature of these checks were, we cannot say, any more than with most +other animals. We know that horses and cattle, which are not extremely +prolific animals, when first turned loose in South America, increased at an +enormous rate. The elephant, the slowest breeder of all known animals, +would in a few thousand years stock the whole world. The increase of every +species of monkey must be checked by some means; but not, as Brehm remarks, +by the attacks of beasts of prey. No one will assume that the actual power +of reproduction in the wild horses and cattle of America, was at first in +any sensible degree increased; or that, as each district became fully +stocked, this same power was diminished. No doubt, in this case, and in +all others, many checks concur, and different checks under different +circumstances; periodical dearths, depending on unfavourable seasons, being +probably the most important of all. So it will have been with the early +progenitors of man. + +NATURAL SELECTION. + +We have now seen that man is variable in body and mind; and that the +variations are induced, either directly or indirectly, by the same general +causes, and obey the same general laws, as with the lower animals. Man has +spread widely over the face of the earth, and must have been exposed, +during his incessant migrations (63. See some good remarks to this effect +by W. Stanley Jevons, "A Deduction from Darwin's Theory," 'Nature,' 1869, +p. 231.), to the most diversified conditions. The inhabitants of Tierra +del Fuego, the Cape of Good Hope, and Tasmania in the one hemisphere, and +of the arctic regions in the other, must have passed through many climates, +and changed their habits many times, before they reached their present +homes. (64. Latham, 'Man and his Migrations,' 1851, p. 135.) The early +progenitors of man must also have tended, like all other animals, to have +increased beyond their means of subsistence; they must, therefore, +occasionally have been exposed to a struggle for existence, and +consequently to the rigid law of natural selection. Beneficial variations +of all kinds will thus, either occasionally or habitually, have been +preserved and injurious ones eliminated. I do not refer to strongly-marked +deviations of structure, which occur only at long intervals of time, but to +mere individual differences. We know, for instance, that the muscles of +our hands and feet, which determine our powers of movement, are liable, +like those of the lower animals, (65. Messrs. Murie and Mivart in their +'Anatomy of the Lemuroidea' ('Transact. Zoolog. Soc.' vol. vii. 1869, pp. +96-98) say, "some muscles are so irregular in their distribution that they +cannot be well classed in any of the above groups." These muscles differ +even on the opposite sides of the same individual.) to incessant +variability. If then the progenitors of man inhabiting any district, +especially one undergoing some change in its conditions, were divided into +two equal bodies, the one half which included all the individuals best +adapted by their powers of movement for gaining subsistence, or for +defending themselves, would on an average survive in greater numbers, and +procreate more offspring than the other and less well endowed half. + +Man in the rudest state in which he now exists is the most dominant animal +that has ever appeared on this earth. He has spread more widely than any +other highly organised form: and all others have yielded before him. He +manifestly owes this immense superiority to his intellectual faculties, to +his social habits, which lead him to aid and defend his fellows, and to his +corporeal structure. The supreme importance of these characters has been +proved by the final arbitrament of the battle for life. Through his powers +of intellect, articulate language has been evolved; and on this his +wonderful advancement has mainly depended. As Mr. Chauncey Wright remarks +(66. Limits of Natural Selection, 'North American Review,' Oct. 1870, p. +295.): "a psychological analysis of the faculty of language shews, that +even the smallest proficiency in it might require more brain power than the +greatest proficiency in any other direction." He has invented and is able +to use various weapons, tools, traps, etc., with which he defends himself, +kills or catches prey, and otherwise obtains food. He has made rafts or +canoes for fishing or crossing over to neighbouring fertile islands. He +has discovered the art of making fire, by which hard and stringy roots can +be rendered digestible, and poisonous roots or herbs innocuous. This +discovery of fire, probably the greatest ever made by man, excepting +language, dates from before the dawn of history. These several inventions, +by which man in the rudest state has become so pre-eminent, are the direct +results of the development of his powers of observation, memory, curiosity, +imagination, and reason. I cannot, therefore, understand how it is that +Mr. Wallace (67. 'Quarterly Review,' April 1869, p. 392. This subject is +more fully discussed in Mr. Wallace's 'Contributions to the Theory of +Natural Selection,' 1870, in which all the essays referred to in this work +are re-published. The 'Essay on Man,' has been ably criticised by Prof. +Claparede, one of the most distinguished zoologists in Europe, in an +article published in the 'Bibliotheque Universelle,' June 1870. The remark +quoted in my text will surprise every one who has read Mr. Wallace's +celebrated paper on 'The Origin of Human Races Deduced from the Theory of +Natural Selection,' originally published in the 'Anthropological Review,' +May 1864, p. clviii. I cannot here resist quoting a most just remark by +Sir J. Lubbock ('Prehistoric Times,' 1865, p. 479) in reference to this +paper, namely, that Mr. Wallace, "with characteristic unselfishness, +ascribes it (i.e. the idea of natural selection) unreservedly to Mr. +Darwin, although, as is well known, he struck out the idea independently, +and published it, though not with the same elaboration, at the same time.") +maintains, that "natural selection could only have endowed the savage with +a brain a little superior to that of an ape." + +Although the intellectual powers and social habits of man are of paramount +importance to him, we must not underrate the importance of his bodily +structure, to which subject the remainder of this chapter will be devoted; +the development of the intellectual and social or moral faculties being +discussed in a later chapter. + +Even to hammer with precision is no easy matter, as every one who has tried +to learn carpentry will admit. To throw a stone with as true an aim as a +Fuegian in defending himself, or in killing birds, requires the most +consummate perfection in the correlated action of the muscles of the hand, +arm, and shoulder, and, further, a fine sense of touch. In throwing a +stone or spear, and in many other actions, a man must stand firmly on his +feet; and this again demands the perfect co-adaptation of numerous muscles. +To chip a flint into the rudest tool, or to form a barbed spear or hook +from a bone, demands the use of a perfect hand; for, as a most capable +judge, Mr. Schoolcraft (68. Quoted by Mr. Lawson Tait in his 'Law of +Natural Selection,' 'Dublin Quarterly Journal of Medical Science,' Feb. +1869. Dr. Keller is likewise quoted to the same effect.), remarks, the +shaping fragments of stone into knives, lances, or arrow-heads, shews +"extraordinary ability and long practice." This is to a great extent +proved by the fact that primeval men practised a division of labour; each +man did not manufacture his own flint tools or rude pottery, but certain +individuals appear to have devoted themselves to such work, no doubt +receiving in exchange the produce of the chase. Archaeologists are +convinced that an enormous interval of time elapsed before our ancestors +thought of grinding chipped flints into smooth tools. One can hardly +doubt, that a man-like animal who possessed a hand and arm sufficiently +perfect to throw a stone with precision, or to form a flint into a rude +tool, could, with sufficient practice, as far as mechanical skill alone is +concerned, make almost anything which a civilised man can make. The +structure of the hand in this respect may be compared with that of the +vocal organs, which in the apes are used for uttering various signal-cries, +or, as in one genus, musical cadences; but in man the closely similar vocal +organs have become adapted through the inherited effects of use for the +utterance of articulate language. + +Turning now to the nearest allies of men, and therefore to the best +representatives of our early progenitors, we find that the hands of the +Quadrumana are constructed on the same general pattern as our own, but are +far less perfectly adapted for diversified uses. Their hands do not serve +for locomotion so well as the feet of a dog; as may be seen in such monkeys +as the chimpanzee and orang, which walk on the outer margins of the palms, +or on the knuckles. (69. Owen, 'Anatomy of Vertebrates,' vol. iii. p. +71.) Their hands, however, are admirably adapted for climbing trees. +Monkeys seize thin branches or ropes, with the thumb on one side and the +fingers and palm on the other, in the same manner as we do. They can thus +also lift rather large objects, such as the neck of a bottle, to their +mouths. Baboons turn over stones, and scratch up roots with their hands. +They seize nuts, insects, or other small objects with the thumb in +opposition to the fingers, and no doubt they thus extract eggs and young +from the nests of birds. American monkeys beat the wild oranges on the +branches until the rind is cracked, and then tear it off with the fingers +of the two hands. In a wild state they break open hard fruits with stones. +Other monkeys open mussel-shells with the two thumbs. With their fingers +they pull out thorns and burs, and hunt for each other's parasites. They +roll down stones, or throw them at their enemies: nevertheless, they are +clumsy in these various actions, and, as I have myself seen, are quite +unable to throw a stone with precision. + +It seems to me far from true that because "objects are grasped clumsily" by +monkeys, "a much less specialised organ of prehension" would have served +them (70. 'Quarterly Review,' April 1869, p. 392.) equally well with their +present hands. On the contrary, I see no reason to doubt that more +perfectly constructed hands would have been an advantage to them, provided +that they were not thus rendered less fitted for climbing trees. We may +suspect that a hand as perfect as that of man would have been +disadvantageous for climbing; for the most arboreal monkeys in the world, +namely, Ateles in America, Colobus in Africa, and Hylobates in Asia, are +either thumbless, or their toes partially cohere, so that their limbs are +converted into mere grasping hooks. (71. In Hylobates syndactylus, as the +name expresses, two of the toes regularly cohere; and this, as Mr. Blyth +informs me, is occasionally the case with the toes of H. agilis, lar, and +leuciscus. Colobus is strictly arboreal and extraordinarily active (Brehm, +'Thierleben,' B. i. s. 50), but whether a better climber than the species +of the allied genera, I do not know. It deserves notice that the feet of +the sloths, the most arboreal animals in the world, are wonderfully hook- +like. + +As soon as some ancient member in the great series of the Primates came to +be less arboreal, owing to a change in its manner of procuring subsistence, +or to some change in the surrounding conditions, its habitual manner of +progression would have been modified: and thus it would have been rendered +more strictly quadrupedal or bipedal. Baboons frequent hilly and rocky +districts, and only from necessity climb high trees (72. Brehm, +'Thierleben,' B. i. s. 80.); and they have acquired almost the gait of a +dog. Man alone has become a biped; and we can, I think, partly see how he +has come to assume his erect attitude, which forms one of his most +conspicuous characters. Man could not have attained his present dominant +position in the world without the use of his hands, which are so admirably +adapted to act in obedience to his will. Sir C. Bell (73. 'The Hand,' +etc., 'Bridgewater Treatise,' 1833, p. 38.) insists that "the hand supplies +all instruments, and by its correspondence with the intellect gives him +universal dominion." But the hands and arms could hardly have become +perfect enough to have manufactured weapons, or to have hurled stones and +spears with a true aim, as long as they were habitually used for locomotion +and for supporting the whole weight of the body, or, as before remarked, so +long as they were especially fitted for climbing trees. Such rough +treatment would also have blunted the sense of touch, on which their +delicate use largely depends. From these causes alone it would have been +an advantage to man to become a biped; but for many actions it is +indispensable that the arms and whole upper part of the body should be +free; and he must for this end stand firmly on his feet. To gain this +great advantage, the feet have been rendered flat; and the great toe has +been peculiarly modified, though this has entailed the almost complete loss +of its power of prehension. It accords with the principle of the division +of physiological labour, prevailing throughout the animal kingdom, that as +the hands became perfected for prehension, the feet should have become +perfected for support and locomotion. With some savages, however, the foot +has not altogether lost its prehensile power, as shewn by their manner of +climbing trees, and of using them in other ways. (74. Haeckel has an +excellent discussion on the steps by which man became a biped: 'Natürliche +Schöpfungsgeschicte,' 1868, s. 507. Dr. Buchner ('Conférences sur la +Théorie Darwinienne,' 1869, p. 135) has given good cases of the use of the +foot as a prehensile organ by man; and has also written on the manner of +progression of the higher apes, to which I allude in the following +paragraph: see also Owen ('Anatomy of Vertebrates,' vol. iii. p. 71) on +this latter subject. + +If it be an advantage to man to stand firmly on his feet and to have his +hands and arms free, of which, from his pre-eminent success in the battle +of life there can be no doubt, then I can see no reason why it should not +have been advantageous to the progenitors of man to have become more and +more erect or bipedal. They would thus have been better able to defend +themselves with stones or clubs, to attack their prey, or otherwise to +obtain food. The best built individuals would in the long run have +succeeded best, and have survived in larger numbers. If the gorilla and a +few allied forms had become extinct, it might have been argued, with great +force and apparent truth, that an animal could not have been gradually +converted from a quadruped into a biped, as all the individuals in an +intermediate condition would have been miserably ill-fitted for +progression. But we know (and this is well worthy of reflection) that the +anthropomorphous apes are now actually in an intermediate condition; and no +one doubts that they are on the whole well adapted for their conditions of +life. Thus the gorilla runs with a sidelong shambling gait, but more +commonly progresses by resting on its bent hands. The long-armed apes +occasionally use their arms like crutches, swinging their bodies forward +between them, and some kinds of Hylobates, without having been taught, can +walk or run upright with tolerable quickness; yet they move awkwardly, and +much less securely than man. We see, in short, in existing monkeys a +manner of progression intermediate between that of a quadruped and a biped; +but, as an unprejudiced judge (75. Prof. Broca, La Constitution des +Vertèbres caudales; 'La Revue d'Anthropologie,' 1872, p. 26, (separate +copy).) insists, the anthropomorphous apes approach in structure more +nearly to the bipedal than to the quadrupedal type. + +As the progenitors of man became more and more erect, with their hands and +arms more and more modified for prehension and other purposes, with their +feet and legs at the same time transformed for firm support and +progression, endless other changes of structure would have become +necessary. The pelvis would have to be broadened, the spine peculiarly +curved, and the head fixed in an altered position, all which changes have +been attained by man. Prof. Schaaffhausen (76. 'On the Primitive Form of +the Skull,' translated in 'Anthropological Review,' Oct. 1868, p. 428. +Owen ('Anatomy of Vertebrates,' vol. ii. 1866, p. 551) on the mastoid +processes in the higher apes.) maintains that "the powerful mastoid +processes of the human skull are the result of his erect position;" and +these processes are absent in the orang, chimpanzee, etc., and are smaller +in the gorilla than in man. Various other structures, which appear +connected with man's erect position, might here have been added. It is +very difficult to decide how far these correlated modifications are the +result of natural selection, and how far of the inherited effects of the +increased use of certain parts, or of the action of one part on another. +No doubt these means of change often co-operate: thus when certain +muscles, and the crests of bone to which they are attached, become enlarged +by habitual use, this shews that certain actions are habitually performed +and must be serviceable. Hence the individuals which performed them best, +would tend to survive in greater numbers. + +The free use of the arms and hands, partly the cause and partly the result +of man's erect position, appears to have led in an indirect manner to other +modifications of structure. The early male forefathers of man were, as +previously stated, probably furnished with great canine teeth; but as they +gradually acquired the habit of using stones, clubs, or other weapons, for +fighting with their enemies or rivals, they would use their jaws and teeth +less and less. In this case, the jaws, together with the teeth, would +become reduced in size, as we may feel almost sure from innumerable +analogous cases. In a future chapter we shall meet with a closely parallel +case, in the reduction or complete disappearance of the canine teeth in +male ruminants, apparently in relation with the development of their horns; +and in horses, in relation to their habit of fighting with their incisor +teeth and hoofs. + +In the adult male anthropomorphous apes, as Rutimeyer (77. 'Die Grenzen +der Thierwelt, eine Betrachtung zu Darwin's Lehre,' 1868, s. 51.), and +others, have insisted, it is the effect on the skull of the great +development of the jaw-muscles that causes it to differ so greatly in many +respects from that of man, and has given to these animals "a truly +frightful physiognomy." Therefore, as the jaws and teeth in man's +progenitors gradually become reduced in size, the adult skull would have +come to resemble more and more that of existing man. As we shall hereafter +see, a great reduction of the canine teeth in the males would almost +certainly affect the teeth of the females through inheritance. + +As the various mental faculties gradually developed themselves the brain +would almost certainly become larger. No one, I presume, doubts that the +large proportion which the size of man's brain bears to his body, compared +to the same proportion in the gorilla or orang, is closely connected with +his higher mental powers. We meet with closely analogous facts with +insects, for in ants the cerebral ganglia are of extraordinary dimensions, +and in all the Hymenoptera these ganglia are many times larger than in the +less intelligent orders, such as beetles. (78. Dujardin, 'Annales des +Sciences Nat.' 3rd series, Zoolog., tom. xiv. 1850, p. 203. See also Mr. +Lowne, 'Anatomy and Phys. of the Musca vomitoria,' 1870, p. 14. My son, +Mr. F. Darwin, dissected for me the cerebral ganglia of the Formica rufa.) +On the other hand, no one supposes that the intellect of any two animals or +of any two men can be accurately gauged by the cubic contents of their +skulls. It is certain that there may be extraordinary mental activity with +an extremely small absolute mass of nervous matter: thus the wonderfully +diversified instincts, mental powers, and affections of ants are notorious, +yet their cerebral ganglia are not so large as the quarter of a small pin's +head. Under this point of view, the brain of an ant is one of the most +marvellous atoms of matter in the world, perhaps more so than the brain of +a man. + +The belief that there exists in man some close relation between the size of +the brain and the development of the intellectual faculties is supported by +the comparison of the skulls of savage and civilised races, of ancient and +modern people, and by the analogy of the whole vertebrate series. Dr. J. +Barnard Davis has proved (79. 'Philosophical Transactions,' 1869, p. +513.), by many careful measurements, that the mean internal capacity of the +skull in Europeans is 92.3 cubic inches; in Americans 87.5; in Asiatics +87.1; and in Australians only 81.9 cubic inches. Professor Broca (80. +'Les Selections,' M. P. Broca, 'Revue d'Anthropologies,' 1873; see also, as +quoted in C. Vogt's 'Lectures on Man,' Engl. translat., 1864, pp. 88, 90. +Prichard, 'Physical History of Mankind,' vol. i. 1838, p. 305.) found that +the nineteenth century skulls from graves in Paris were larger than those +from vaults of the twelfth century, in the proportion of 1484 to 1426; and +that the increased size, as ascertained by measurements, was exclusively in +the frontal part of the skull--the seat of the intellectual faculties. +Prichard is persuaded that the present inhabitants of Britain have "much +more capacious brain-cases" than the ancient inhabitants. Nevertheless, it +must be admitted that some skulls of very high antiquity, such as the +famous one of Neanderthal, are well developed and capacious. (81. In the +interesting article just referred to, Prof. Broca has well remarked, that +in civilised nations, the average capacity of the skull must be lowered by +the preservation of a considerable number of individuals, weak in mind and +body, who would have been promptly eliminated in the savage state. On the +other hand, with savages, the average includes only the more capable +individuals, who have been able to survive under extremely hard conditions +of life. Broca thus explains the otherwise inexplicable fact, that the +mean capacity of the skull of the ancient Troglodytes of Lozere is greater +than that of modern Frenchmen.) With respect to the lower animals, M.E. +Lartet (82. 'Comptes-rendus des Sciences,' etc., June 1, 1868.), by +comparing the crania of tertiary and recent mammals belonging to the same +groups, has come to the remarkable conclusion that the brain is generally +larger and the convolutions are more complex in the more recent forms. On +the other hand, I have shewn (83. The 'Variation of Animals and Plants +under Domestication,' vol. i. pp. 124-129.) that the brains of domestic +rabbits are considerably reduced in bulk, in comparison with those of the +wild rabbit or hare; and this may be attributed to their having been +closely confined during many generations, so that they have exerted their +intellect, instincts, senses and voluntary movements but little. + +The gradually increasing weight of the brain and skull in man must have +influenced the development of the supporting spinal column, more especially +whilst he was becoming erect. As this change of position was being brought +about, the internal pressure of the brain will also have influenced the +form of the skull; for many facts shew how easily the skull is thus +affected. Ethnologists believe that it is modified by the kind of cradle +in which infants sleep. Habitual spasms of the muscles, and a cicatrix +from a severe burn, have permanently modified the facial bones. In young +persons whose heads have become fixed either sideways or backwards, owing +to disease, one of the two eyes has changed its position, and the shape of +the skull has been altered apparently by the pressure of the brain in a new +direction. (84. Schaaffhausen gives from Blumenbach and Busch, the cases +of the spasms and cicatrix, in 'Anthropological Review,' Oct. 1868, p. 420. +Dr. Jarrold ('Anthropologia,' 1808, pp. 115, 116) adduces from Camper and +from his own observations, cases of the modification of the skull from the +head being fixed in an unnatural position. He believes that in certain +trades, such as that of a shoemaker, where the head is habitually held +forward, the forehead becomes more rounded and prominent.) I have shewn +that with long-eared rabbits even so trifling a cause as the lopping +forward of one ear drags forward almost every bone of the skull on that +side; so that the bones on the opposite side no longer strictly correspond. +Lastly, if any animal were to increase or diminish much in general size, +without any change in its mental powers, or if the mental powers were to be +much increased or diminished, without any great change in the size of the +body, the shape of the skull would almost certainly be altered. I infer +this from my observations on domestic rabbits, some kinds of which have +become very much larger than the wild animal, whilst others have retained +nearly the same size, but in both cases the brain has been much reduced +relatively to the size of the body. Now I was at first much surprised on +finding that in all these rabbits the skull had become elongated or +dolichocephalic; for instance, of two skulls of nearly equal breadth, the +one from a wild rabbit and the other from a large domestic kind, the former +was 3.15 and the latter 4.3 inches in length. (85. 'Variation of Animals +and Plants under Domestication,' vol. i. p. 117, on the elongation of the +skull; p. 119, on the effect of the lopping of one ear.) One of the most +marked distinctions in different races of men is that the skull in some is +elongated, and in others rounded; and here the explanation suggested by the +case of the rabbits may hold good; for Welcker finds that short "men +incline more to brachycephaly, and tall men to dolichocephaly" (86. Quoted +by Schaaffhausen, in 'Anthropological Review,' Oct. 1868, p. 419.); and +tall men may be compared with the larger and longer-bodied rabbits, all of +which have elongated skulls or are dolichocephalic. + +From these several facts we can understand, to a certain extent, the means +by which the great size and more or less rounded form of the skull have +been acquired by man; and these are characters eminently distinctive of him +in comparison with the lower animals. + +Another most conspicuous difference between man and the lower animals is +the nakedness of his skin. Whales and porpoises (Cetacea), dugongs +(Sirenia) and the hippopotamus are naked; and this may be advantageous to +them for gliding through the water; nor would it be injurious to them from +the loss of warmth, as the species, which inhabit the colder regions, are +protected by a thick layer of blubber, serving the same purpose as the fur +of seals and otters. Elephants and rhinoceroses are almost hairless; and +as certain extinct species, which formerly lived under an Arctic climate, +were covered with long wool or hair, it would almost appear as if the +existing species of both genera had lost their hairy covering from exposure +to heat. This appears the more probable, as the elephants in India which +live on elevated and cool districts are more hairy (87. Owen, 'Anatomy of +Vertebrates,' vol. iii. p. 619.) than those on the lowlands. May we then +infer that man became divested of hair from having aboriginally inhabited +some tropical land? That the hair is chiefly retained in the male sex on +the chest and face, and in both sexes at the junction of all four limbs +with the trunk, favours this inference--on the assumption that the hair was +lost before man became erect; for the parts which now retain most hair +would then have been most protected from the heat of the sun. The crown of +the head, however, offers a curious exception, for at all times it must +have been one of the most exposed parts, yet it is thickly clothed with +hair. The fact, however, that the other members of the order of Primates, +to which man belongs, although inhabiting various hot regions, are well +clothed with hair, generally thickest on the upper surface (88. Isidore +Geoffroy St.-Hilaire remarks ('Histoire Nat. Generale,' tom. ii. 1859, pp. +215-217) on the head of man being covered with long hair; also on the upper +surfaces of monkeys and of other mammals being more thickly clothed than +the lower surfaces. This has likewise been observed by various authors. +Prof. P. Gervais ('Histoire Nat. des Mammifères,' tom. i. 1854, p. 28), +however, states that in the Gorilla the hair is thinner on the back, where +it is partly rubbed off, than on the lower surface.), is opposed to the +supposition that man became naked through the action of the sun. Mr. Belt +believes (89. The 'Naturalist in Nicaragua,' 1874, p. 209. As some +confirmation of Mr. Belt's view, I may quote the following passage from Sir +W. Denison ('Varieties of Vice-Regal Life,' vol. i. 1870, p. 440): "It is +said to be a practice with the Australians, when the vermin get +troublesome, to singe themselves.") that within the tropics it is an +advantage to man to be destitute of hair, as he is thus enabled to free +himself of the multitude of ticks (acari) and other parasites, with which +he is often infested, and which sometimes cause ulceration. But whether +this evil is of sufficient magnitude to have led to the denudation of his +body through natural selection, may be doubted, since none of the many +quadrupeds inhabiting the tropics have, as far as I know, acquired any +specialised means of relief. The view which seems to me the most probable +is that man, or rather primarily woman, became divested of hair for +ornamental purposes, as we shall see under Sexual Selection; and, according +to this belief, it is not surprising that man should differ so greatly in +hairiness from all other Primates, for characters, gained through sexual +selection, often differ to an extraordinary degree in closely related +forms. + +According to a popular impression, the absence of a tail is eminently +distinctive of man; but as those apes which come nearest to him are +destitute of this organ, its disappearance does not relate exclusively to +man. The tail often differs remarkably in length within the same genus: +thus in some species of Macacus it is longer than the whole body, and is +formed of twenty-four vertebrae; in others it consists of a scarcely +visible stump, containing only three or four vertebrae. In some kinds of +baboons there are twenty-five, whilst in the mandrill there are ten very +small stunted caudal vertebrae, or, according to Cuvier (90. Mr. St. +George Mivart, 'Proc. Zoolog. Soc.' 1865, pp. 562, 583. Dr. J.E. Gray, +'Cat. Brit. Mus.: 'Skeletons.' Owen, 'Anatomy of Vertebrates,' vol. ii. +p. 517. Isidore Geoffroy, 'Hist. Nat. Gen.' tom. ii. p. 244.), sometimes +only five. The tail, whether it be long or short, almost always tapers +towards the end; and this, I presume, results from the atrophy of the +terminal muscles, together with their arteries and nerves, through disuse, +leading to the atrophy of the terminal bones. But no explanation can at +present be given of the great diversity which often occurs in its length. +Here, however, we are more specially concerned with the complete external +disappearance of the tail. Professor Broca has recently shewn (91. 'Revue +d'Anthropologie,' 1872; 'La Constitution des vertèbres caudales.') that the +tail in all quadrupeds consists of two portions, generally separated +abruptly from each other; the basal portion consists of vertebrae, more or +less perfectly channelled and furnished with apophyses like ordinary +vertebrae; whereas those of the terminal portion are not channelled, are +almost smooth, and scarcely resemble true vertebrae. A tail, though not +externally visible, is really present in man and the anthropomorphous apes, +and is constructed on exactly the same pattern in both. In the terminal +portion the vertabrae, constituting the os coccyx, are quite rudimentary, +being much reduced in size and number. In the basal portion, the vertebrae +are likewise few, are united firmly together, and are arrested in +development; but they have been rendered much broader and flatter than the +corresponding vertebrae in the tails of other animals: they constitute +what Broca calls the accessory sacral vertebrae. These are of functional +importance by supporting certain internal parts and in other ways; and +their modification is directly connected with the erect or semi-erect +attitude of man and the anthropomorphous apes. This conclusion is the more +trustworthy, as Broca formerly held a different view, which he has now +abandoned. The modification, therefore, of the basal caudal vertebrae in +man and the higher apes may have been effected, directly or indirectly, +through natural selection. + +But what are we to say about the rudimentary and variable vertebrae of the +terminal portion of the tail, forming the os coccyx? A notion which has +often been, and will no doubt again be ridiculed, namely, that friction has +had something to do with the disappearance of the external portion of the +tail, is not so ridiculous as it at first appears. Dr. Anderson (92. +'Proceedings Zoological Society,' 1872, p. 210.) states that the extremely +short tail of Macacus brunneus is formed of eleven vertebrae, including the +imbedded basal ones. The extremity is tendinous and contains no vertebrae; +this is succeeded by five rudimentary ones, so minute that together they +are only one line and a half in length, and these are permanently bent to +one side in the shape of a hook. The free part of the tail, only a little +above an inch in length, includes only four more small vertebrae. This +short tail is carried erect; but about a quarter of its total length is +doubled on to itself to the left; and this terminal part, which includes +the hook-like portion, serves "to fill up the interspace between the upper +divergent portion of the callosities;" so that the animal sits on it, and +thus renders it rough and callous. Dr. Anderson thus sums up his +observations: "These facts seem to me to have only one explanation; this +tail, from its short size, is in the monkey's way when it sits down, and +frequently becomes placed under the animal while it is in this attitude; +and from the circumstance that it does not extend beyond the extremity of +the ischial tuberosities, it seems as if the tail originally had been bent +round by the will of the animal, into the interspace between the +callosities, to escape being pressed between them and the ground, and that +in time the curvature became permanent, fitting in of itself when the organ +happens to be sat upon." Under these circumstances it is not surprising +that the surface of the tail should have been roughened and rendered +callous, and Dr. Murie (93. 'Proceedings Zoological Society,' 1872, p. +786.), who carefully observed this species in the Zoological Gardens, as +well as three other closely allied forms with slightly longer tails, says +that when the animal sits down, the tail "is necessarily thrust to one side +of the buttocks; and whether long or short its root is consequently liable +to be rubbed or chafed." As we now have evidence that mutilations +occasionally produce an inherited effect (94. I allude to Dr. Brown- +Sequard's observations on the transmitted effect of an operation causing +epilepsy in guinea-pigs, and likewise more recently on the analogous +effects of cutting the sympathetic nerve in the neck. I shall hereafter +have occasion to refer to Mr. Salvin's interesting case of the apparently +inherited effects of mot-mots biting off the barbs of their own tail- +feathers. See also on the general subject 'Variation of Animals and Plants +under Domestication,' vol. ii. pp. 22-24.), it is not very improbable that +in short-tailed monkeys, the projecting part of the tail, being +functionally useless, should after many generations have become rudimentary +and distorted, from being continually rubbed and chafed. We see the +projecting part in this condition in the Macacus brunneus, and absolutely +aborted in the M. ecaudatus and in several of the higher apes. Finally, +then, as far as we can judge, the tail has disappeared in man and the +anthropomorphous apes, owing to the terminal portion having been injured by +friction during a long lapse of time; the basal and embedded portion having +been reduced and modified, so as to become suitable to the erect or semi- +erect position. + +I have now endeavoured to shew that some of the most distinctive characters +of man have in all probability been acquired, either directly, or more +commonly indirectly, through natural selection. We should bear in mind +that modifications in structure or constitution which do not serve to adapt +an organism to its habits of life, to the food which it consumes, or +passively to the surrounding conditions, cannot have been thus acquired. +We must not, however, be too confident in deciding what modifications are +of service to each being: we should remember how little we know about the +use of many parts, or what changes in the blood or tissues may serve to fit +an organism for a new climate or new kinds of food. Nor must we forget the +principle of correlation, by which, as Isidore Geoffroy has shewn in the +case of man, many strange deviations of structure are tied together. +Independently of correlation, a change in one part often leads, through the +increased or decreased use of other parts, to other changes of a quite +unexpected nature. It is also well to reflect on such facts, as the +wonderful growth of galls on plants caused by the poison of an insect, and +on the remarkable changes of colour in the plumage of parrots when fed on +certain fishes, or inoculated with the poison of toads (95. The 'Variation +of Animals and Plants under Domestication,' vol. ii. pp. 280, 282.); for we +can thus see that the fluids of the system, if altered for some special +purpose, might induce other changes. We should especially bear in mind +that modifications acquired and continually used during past ages for some +useful purpose, would probably become firmly fixed, and might be long +inherited. + +Thus a large yet undefined extension may safely be given to the direct and +indirect results of natural selection; but I now admit, after reading the +essay by Nageli on plants, and the remarks by various authors with respect +to animals, more especially those recently made by Professor Broca, that in +the earlier editions of my 'Origin of Species' I perhaps attributed too +much to the action of natural selection or the survival of the fittest. I +have altered the fifth edition of the 'Origin' so as to confine my remarks +to adaptive changes of structure; but I am convinced, from the light gained +during even the last few years, that very many structures which now appear +to us useless, will hereafter be proved to be useful, and will therefore +come within the range of natural selection. Nevertheless, I did not +formerly consider sufficiently the existence of structures, which, as far +as we can at present judge, are neither beneficial nor injurious; and this +I believe to be one of the greatest oversights as yet detected in my work. +I may be permitted to say, as some excuse, that I had two distinct objects +in view; firstly, to shew that species had not been separately created, and +secondly, that natural selection had been the chief agent of change, though +largely aided by the inherited effects of habit, and slightly by the direct +action of the surrounding conditions. I was not, however, able to annul +the influence of my former belief, then almost universal, that each species +had been purposely created; and this led to my tacit assumption that every +detail of structure, excepting rudiments, was of some special, though +unrecognised, service. Any one with this assumption in his mind would +naturally extend too far the action of natural selection, either during +past or present times. Some of those who admit the principle of evolution, +but reject natural selection, seem to forget, when criticising my book, +that I had the above two objects in view; hence if I have erred in giving +to natural selection great power, which I am very far from admitting, or in +having exaggerated its power, which is in itself probable, I have at least, +as I hope, done good service in aiding to overthrow the dogma of separate +creations. + +It is, as I can now see, probable that all organic beings, including man, +possess peculiarities of structure, which neither are now, nor were +formerly of any service to them, and which, therefore, are of no +physiological importance. We know not what produces the numberless slight +differences between the individuals of each species, for reversion only +carries the problem a few steps backwards, but each peculiarity must have +had its efficient cause. If these causes, whatever they may be, were to +act more uniformly and energetically during a lengthened period (and +against this no reason can be assigned), the result would probably be not a +mere slight individual difference, but a well-marked and constant +modification, though one of no physiological importance. Changed +structures, which are in no way beneficial, cannot be kept uniform through +natural selection, though the injurious will be thus eliminated. +Uniformity of character would, however, naturally follow from the assumed +uniformity of the exciting causes, and likewise from the free intercrossing +of many individuals. During successive periods, the same organism might in +this manner acquire successive modifications, which would be transmitted in +a nearly uniform state as long as the exciting causes remained the same and +there was free intercrossing. With respect to the exciting causes we can +only say, as when speaking of so-called spontaneous variations, that they +relate much more closely to the constitution of the varying organism, than +to the nature of the conditions to which it has been subjected. + +CONCLUSION. + +In this chapter we have seen that as man at the present day is liable, like +every other animal, to multiform individual differences or slight +variations, so no doubt were the early progenitors of man; the variations +being formerly induced by the same general causes, and governed by the same +general and complex laws as at present. As all animals tend to multiply +beyond their means of subsistence, so it must have been with the +progenitors of man; and this would inevitably lead to a struggle for +existence and to natural selection. The latter process would be greatly +aided by the inherited effects of the increased use of parts, and these two +processes would incessantly react on each other. It appears, also, as we +shall hereafter see, that various unimportant characters have been acquired +by man through sexual selection. An unexplained residuum of change must be +left to the assumed uniform action of those unknown agencies, which +occasionally induce strongly marked and abrupt deviations of structure in +our domestic productions. + +Judging from the habits of savages and of the greater number of the +Quadrumana, primeval men, and even their ape-like progenitors, probably +lived in society. With strictly social animals, natural selection +sometimes acts on the individual, through the preservation of variations +which are beneficial to the community. A community which includes a large +number of well-endowed individuals increases in number, and is victorious +over other less favoured ones; even although each separate member gains no +advantage over the others of the same community. Associated insects have +thus acquired many remarkable structures, which are of little or no service +to the individual, such as the pollen-collecting apparatus, or the sting of +the worker-bee, or the great jaws of soldier-ants. With the higher social +animals, I am not aware that any structure has been modified solely for the +good of the community, though some are of secondary service to it. For +instance, the horns of ruminants and the great canine teeth of baboons +appear to have been acquired by the males as weapons for sexual strife, but +they are used in defence of the herd or troop. In regard to certain mental +powers the case, as we shall see in the fifth chapter, is wholly different; +for these faculties have been chiefly, or even exclusively, gained for the +benefit of the community, and the individuals thereof have at the same time +gained an advantage indirectly. + +It has often been objected to such views as the foregoing, that man is one +of the most helpless and defenceless creatures in the world; and that +during his early and less well-developed condition, he would have been +still more helpless. The Duke of Argyll, for instance, insists (96. +'Primeval Man,' 1869, p. 66.) that "the human frame has diverged from the +structure of brutes, in the direction of greater physical helplessness and +weakness. That is to say, it is a divergence which of all others it is +most impossible to ascribe to mere natural selection." He adduces the +naked and unprotected state of the body, the absence of great teeth or +claws for defence, the small strength and speed of man, and his slight +power of discovering food or of avoiding danger by smell. To these +deficiencies there might be added one still more serious, namely, that he +cannot climb quickly, and so escape from enemies. The loss of hair would +not have been a great injury to the inhabitants of a warm country. For we +know that the unclothed Fuegians can exist under a wretched climate. When +we compare the defenceless state of man with that of apes, we must remember +that the great canine teeth with which the latter are provided, are +possessed in their full development by the males alone, and are chiefly +used by them for fighting with their rivals; yet the females, which are not +thus provided, manage to survive. + +In regard to bodily size or strength, we do not know whether man is +descended from some small species, like the chimpanzee, or from one as +powerful as the gorilla; and, therefore, we cannot say whether man has +become larger and stronger, or smaller and weaker, than his ancestors. We +should, however, bear in mind that an animal possessing great size, +strength, and ferocity, and which, like the gorilla, could defend itself +from all enemies, would not perhaps have become social: and this would +most effectually have checked the acquirement of the higher mental +qualities, such as sympathy and the love of his fellows. Hence it might +have been an immense advantage to man to have sprung from some +comparatively weak creature. + +The small strength and speed of man, his want of natural weapons, etc., are +more than counterbalanced, firstly, by his intellectual powers, through +which he has formed for himself weapons, tools, etc., though still +remaining in a barbarous state, and, secondly, by his social qualities +which lead him to give and receive aid from his fellow-men. No country in +the world abounds in a greater degree with dangerous beasts than Southern +Africa; no country presents more fearful physical hardships than the Arctic +regions; yet one of the puniest of races, that of the Bushmen, maintains +itself in Southern Africa, as do the dwarfed Esquimaux in the Arctic +regions. The ancestors of man were, no doubt, inferior in intellect, and +probably in social disposition, to the lowest existing savages; but it is +quite conceivable that they might have existed, or even flourished, if +they had advanced in intellect, whilst gradually losing their brute-like +powers, such as that of climbing trees, etc. But these ancestors would not +have been exposed to any special danger, even if far more helpless and +defenceless than any existing savages, had they inhabited some warm +continent or large island, such as Australia, New Guinea, or Borneo, which +is now the home of the orang. And natural selection arising from the +competition of tribe with tribe, in some such large area as one of these, +together with the inherited effects of habit, would, under favourable +conditions, have sufficed to raise man to his present high position in the +organic scale. + + +CHAPTER III. + +COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS. + +The difference in mental power between the highest ape and the lowest +savage, immense--Certain instincts in common--The emotions--Curiosity-- +Imitation--Attention--Memory--Imagination--Reason--Progressive improvement +--Tools and weapons used by animals--Abstraction, Self-consciousness-- +Language--Sense of beauty--Belief in God, spiritual agencies, +superstitions. + +We have seen in the last two chapters that man bears in his bodily +structure clear traces of his descent from some lower form; but it may be +urged that, as man differs so greatly in his mental power from all other +animals, there must be some error in this conclusion. No doubt the +difference in this respect is enormous, even if we compare the mind of one +of the lowest savages, who has no words to express any number higher than +four, and who uses hardly any abstract terms for common objects or for the +affections (1. See the evidence on those points, as given by Lubbock, +'Prehistoric Times,' p. 354, etc.), with that of the most highly organised +ape. The difference would, no doubt, still remain immense, even if one of +the higher apes had been improved or civilised as much as a dog has been in +comparison with its parent-form, the wolf or jackal. The Fuegians rank +amongst the lowest barbarians; but I was continually struck with surprise +how closely the three natives on board H.M.S. "Beagle," who had lived some +years in England, and could talk a little English, resembled us in +disposition and in most of our mental faculties. If no organic being +excepting man had possessed any mental power, or if his powers had been of +a wholly different nature from those of the lower animals, then we should +never have been able to convince ourselves that our high faculties had been +gradually developed. But it can be shewn that there is no fundamental +difference of this kind. We must also admit that there is a much wider +interval in mental power between one of the lowest fishes, as a lamprey or +lancelet, and one of the higher apes, than between an ape and man; yet this +interval is filled up by numberless gradations. + +Nor is the difference slight in moral disposition between a barbarian, such +as the man described by the old navigator Byron, who dashed his child on +the rocks for dropping a basket of sea-urchins, and a Howard or Clarkson; +and in intellect, between a savage who uses hardly any abstract terms, and +a Newton or Shakspeare. Differences of this kind between the highest men +of the highest races and the lowest savages, are connected by the finest +gradations. Therefore it is possible that they might pass and be developed +into each other. + +My object in this chapter is to shew that there is no fundamental +difference between man and the higher mammals in their mental faculties. +Each division of the subject might have been extended into a separate +essay, but must here be treated briefly. As no classification of the +mental powers has been universally accepted, I shall arrange my remarks in +the order most convenient for my purpose; and will select those facts which +have struck me most, with the hope that they may produce some effect on the +reader. + +With respect to animals very low in the scale, I shall give some additional +facts under Sexual Selection, shewing that their mental powers are much +higher than might have been expected. The variability of the faculties in +the individuals of the same species is an important point for us, and some +few illustrations will here be given. But it would be superfluous to enter +into many details on this head, for I have found on frequent enquiry, that +it is the unanimous opinion of all those who have long attended to animals +of many kinds, including birds, that the individuals differ greatly in +every mental characteristic. In what manner the mental powers were first +developed in the lowest organisms, is as hopeless an enquiry as how life +itself first originated. These are problems for the distant future, if +they are ever to be solved by man. + +As man possesses the same senses as the lower animals, his fundamental +intuitions must be the same. Man has also some few instincts in common, as +that of self-preservation, sexual love, the love of the mother for her new- +born offspring, the desire possessed by the latter to suck, and so forth. +But man, perhaps, has somewhat fewer instincts than those possessed by the +animals which come next to him in the series. The orang in the Eastern +islands, and the chimpanzee in Africa, build platforms on which they sleep; +and, as both species follow the same habit, it might be argued that this +was due to instinct, but we cannot feel sure that it is not the result of +both animals having similar wants, and possessing similar powers of +reasoning. These apes, as we may assume, avoid the many poisonous fruits +of the tropics, and man has no such knowledge: but as our domestic +animals, when taken to foreign lands, and when first turned out in the +spring, often eat poisonous herbs, which they afterwards avoid, we cannot +feel sure that the apes do not learn from their own experience or from that +of their parents what fruits to select. It is, however, certain, as we +shall presently see, that apes have an instinctive dread of serpents, and +probably of other dangerous animals. + +The fewness and the comparative simplicity of the instincts in the higher +animals are remarkable in contrast with those of the lower animals. Cuvier +maintained that instinct and intelligence stand in an inverse ratio to each +other; and some have thought that the intellectual faculties of the higher +animals have been gradually developed from their instincts. But Pouchet, +in an interesting essay (2. 'L'Instinct chez les Insectes,' 'Revue des +Deux Mondes,' Feb. 1870, p. 690.), has shewn that no such inverse ratio +really exists. Those insects which possess the most wonderful instincts +are certainly the most intelligent. In the vertebrate series, the least +intelligent members, namely fishes and amphibians, do not possess complex +instincts; and amongst mammals the animal most remarkable for its +instincts, namely the beaver, is highly intelligent, as will be admitted by +every one who has read Mr. Morgan's excellent work. (3. 'The American +Beaver and His Works,' 1868.) + +Although the first dawnings of intelligence, according to Mr. Herbert +Spencer (4. 'The Principles of Psychology,' 2nd edit., 1870, pp. 418- +443.), have been developed through the multiplication and co-ordination of +reflex actions, and although many of the simpler instincts graduate into +reflex actions, and can hardly be distinguished from them, as in the case +of young animals sucking, yet the more complex instincts seem to have +originated independently of intelligence. I am, however, very far from +wishing to deny that instinctive actions may lose their fixed and untaught +character, and be replaced by others performed by the aid of the free will. +On the other hand, some intelligent actions, after being performed during +several generations, become converted into instincts and are inherited, as +when birds on oceanic islands learn to avoid man. These actions may then +be said to be degraded in character, for they are no longer performed +through reason or from experience. But the greater number of the more +complex instincts appear to have been gained in a wholly different manner, +through the natural selection of variations of simpler instinctive actions. +Such variations appear to arise from the same unknown causes acting on the +cerebral organisation, which induce slight variations or individual +differences in other parts of the body; and these variations, owing to our +ignorance, are often said to arise spontaneously. We can, I think, come to +no other conclusion with respect to the origin of the more complex +instincts, when we reflect on the marvellous instincts of sterile worker- +ants and bees, which leave no offspring to inherit the effects of +experience and of modified habits. + +Although, as we learn from the above-mentioned insects and the beaver, a +high degree of intelligence is certainly compatible with complex instincts, +and although actions, at first learnt voluntarily can soon through habit be +performed with the quickness and certainty of a reflex action, yet it is +not improbable that there is a certain amount of interference between the +development of free intelligence and of instinct,--which latter implies +some inherited modification of the brain. Little is known about the +functions of the brain, but we can perceive that as the intellectual powers +become highly developed, the various parts of the brain must be connected +by very intricate channels of the freest intercommunication; and as a +consequence each separate part would perhaps tend to be less well fitted to +answer to particular sensations or associations in a definite and +inherited--that is instinctive--manner. There seems even to exist some +relation between a low degree of intelligence and a strong tendency to the +formation of fixed, though not inherited habits; for as a sagacious +physician remarked to me, persons who are slightly imbecile tend to act in +everything by routine or habit; and they are rendered much happier if this +is encouraged. + +I have thought this digression worth giving, because we may easily +underrate the mental powers of the higher animals, and especially of man, +when we compare their actions founded on the memory of past events, on +foresight, reason, and imagination, with exactly similar actions +instinctively performed by the lower animals; in this latter case the +capacity of performing such actions has been gained, step by step, through +the variability of the mental organs and natural selection, without any +conscious intelligence on the part of the animal during each successive +generation. No doubt, as Mr. Wallace has argued (5. 'Contributions to the +Theory of Natural Selection,' 1870, p. 212.), much of the intelligent work +done by man is due to imitation and not to reason; but there is this great +difference between his actions and many of those performed by the lower +animals, namely, that man cannot, on his first trial, make, for instance, a +stone hatchet or a canoe, through his power of imitation. He has to learn +his work by practice; a beaver, on the other hand, can make its dam or +canal, and a bird its nest, as well, or nearly as well, and a spider its +wonderful web, quite as well (6. For the evidence on this head, see Mr. J. +Traherne Moggridge's most interesting work, 'Harvesting Ants and Trap-Door +Spiders,' 1873, pp. 126, 128.), the first time it tries as when old and +experienced. + +To return to our immediate subject: the lower animals, like man, +manifestly feel pleasure and pain, happiness and misery. Happiness is +never better exhibited than by young animals, such as puppies, kittens, +lambs, etc., when playing together, like our own children. Even insects +play together, as has been described by that excellent observer, P. Huber +(7. 'Recherches sur les Moeurs des Fourmis,' 1810, p. 173.), who saw ants +chasing and pretending to bite each other, like so many puppies. + +The fact that the lower animals are excited by the same emotions as +ourselves is so well established, that it will not be necessary to weary +the reader by many details. Terror acts in the same manner on them as on +us, causing the muscles to tremble, the heart to palpitate, the sphincters +to be relaxed, and the hair to stand on end. Suspicion, the offspring of +fear, is eminently characteristic of most wild animals. It is, I think, +impossible to read the account given by Sir E. Tennent, of the behaviour of +the female elephants, used as decoys, without admitting that they +intentionally practise deceit, and well know what they are about. Courage +and timidity are extremely variable qualities in the individuals of the +same species, as is plainly seen in our dogs. Some dogs and horses are +ill-tempered, and easily turn sulky; others are good-tempered; and these +qualities are certainly inherited. Every one knows how liable animals are +to furious rage, and how plainly they shew it. Many, and probably true, +anecdotes have been published on the long-delayed and artful revenge of +various animals. The accurate Rengger, and Brehm (8. All the following +statements, given on the authority of these two naturalists, are taken from +Rengger's 'Naturgesch. der Säugethiere von Paraguay,' 1830, s. 41-57, and +from Brehm's 'Thierleben,' B. i. s. 10-87.) state that the American and +African monkeys which they kept tame, certainly revenged themselves. Sir +Andrew Smith, a zoologist whose scrupulous accuracy was known to many +persons, told me the following story of which he was himself an eye- +witness; at the Cape of Good Hope an officer had often plagued a certain +baboon, and the animal, seeing him approaching one Sunday for parade, +poured water into a hole and hastily made some thick mud, which he +skilfully dashed over the officer as he passed by, to the amusement of many +bystanders. For long afterwards the baboon rejoiced and triumphed whenever +he saw his victim. + +The love of a dog for his master is notorious; as an old writer quaintly +says (9. Quoted by Dr. Lauder Lindsay, in his 'Physiology of Mind in the +Lower Animals,' 'Journal of Mental Science,' April 1871, p. 38.), "A dog is +the only thing on this earth that luvs you more than he luvs himself." + +In the agony of death a dog has been known to caress his master, and every +one has heard of the dog suffering under vivisection, who licked the hand +of the operator; this man, unless the operation was fully justified by an +increase of our knowledge, or unless he had a heart of stone, must have +felt remorse to the last hour of his life. + +As Whewell (10. 'Bridgewater Treatise,' p. 263.) has well asked, "who that +reads the touching instances of maternal affection, related so often of the +women of all nations, and of the females of all animals, can doubt that the +principle of action is the same in the two cases?" We see maternal +affection exhibited in the most trifling details; thus Rengger observed an +American monkey (a Cebus) carefully driving away the flies which plagued +her infant; and Duvaucel saw a Hylobates washing the faces of her young +ones in a stream. So intense is the grief of female monkeys for the loss +of their young, that it invariably caused the death of certain kinds kept +under confinement by Brehm in N. Africa. Orphan monkeys were always +adopted and carefully guarded by the other monkeys, both males and females. +One female baboon had so capacious a heart that she not only adopted young +monkeys of other species, but stole young dogs and cats, which she +continually carried about. Her kindness, however, did not go so far as to +share her food with her adopted offspring, at which Brehm was surprised, as +his monkeys always divided everything quite fairly with their own young +ones. An adopted kitten scratched this affectionate baboon, who certainly +had a fine intellect, for she was much astonished at being scratched, and +immediately examined the kitten's feet, and without more ado bit off the +claws. (11. A critic, without any grounds ('Quarterly Review,' July 1871, +p. 72), disputes the possibility of this act as described by Brehm, for the +sake of discrediting my work. Therefore I tried, and found that I could +readily seize with my own teeth the sharp little claws of a kitten nearly +five weeks old.) In the Zoological Gardens, I heard from the keeper that +an old baboon (C. chacma) had adopted a Rhesus monkey; but when a young +drill and mandrill were placed in the cage, she seemed to perceive that +these monkeys, though distinct species, were her nearer relatives, for she +at once rejected the Rhesus and adopted both of them. The young Rhesus, as +I saw, was greatly discontented at being thus rejected, and it would, like +a naughty child, annoy and attack the young drill and mandrill whenever it +could do so with safety; this conduct exciting great indignation in the old +baboon. Monkeys will also, according to Brehm, defend their master when +attacked by any one, as well as dogs to whom they are attached, from the +attacks of other dogs. But we here trench on the subjects of sympathy and +fidelity, to which I shall recur. Some of Brehm's monkeys took much +delight in teasing a certain old dog whom they disliked, as well as other +animals, in various ingenious ways. + +Most of the more complex emotions are common to the higher animals and +ourselves. Every one has seen how jealous a dog is of his master's +affection, if lavished on any other creature; and I have observed the same +fact with monkeys. This shews that animals not only love, but have desire +to be loved. Animals manifestly feel emulation. They love approbation or +praise; and a dog carrying a basket for his master exhibits in a high +degree self-complacency or pride. There can, I think, be no doubt that a +dog feels shame, as distinct from fear, and something very like modesty +when begging too often for food. A great dog scorns the snarling of a +little dog, and this may be called magnanimity. Several observers have +stated that monkeys certainly dislike being laughed at; and they sometimes +invent imaginary offences. In the Zoological Gardens I saw a baboon who +always got into a furious rage when his keeper took out a letter or book +and read it aloud to him; and his rage was so violent that, as I witnessed +on one occasion, he bit his own leg till the blood flowed. Dogs shew what +may be fairly called a sense of humour, as distinct from mere play; if a +bit of stick or other such object be thrown to one, he will often carry it +away for a short distance; and then squatting down with it on the ground +close before him, will wait until his master comes quite close to take it +away. The dog will then seize it and rush away in triumph, repeating the +same manoeuvre, and evidently enjoying the practical joke. + +We will now turn to the more intellectual emotions and faculties, which are +very important, as forming the basis for the development of the higher +mental powers. Animals manifestly enjoy excitement, and suffer from ennui, +as may be seen with dogs, and, according to Rengger, with monkeys. All +animals feel WONDER, and many exhibit CURIOSITY. They sometimes suffer +from this latter quality, as when the hunter plays antics and thus attracts +them; I have witnessed this with deer, and so it is with the wary chamois, +and with some kinds of wild-ducks. Brehm gives a curious account of the +instinctive dread, which his monkeys exhibited, for snakes; but their +curiosity was so great that they could not desist from occasionally +satiating their horror in a most human fashion, by lifting up the lid of +the box in which the snakes were kept. I was so much surprised at his +account, that I took a stuffed and coiled-up snake into the monkey-house at +the Zoological Gardens, and the excitement thus caused was one of the most +curious spectacles which I ever beheld. Three species of Cercopithecus +were the most alarmed; they dashed about their cages, and uttered sharp +signal cries of danger, which were understood by the other monkeys. A few +young monkeys and one old Anubis baboon alone took no notice of the snake. +I then placed the stuffed specimen on the ground in one of the larger +compartments. After a time all the monkeys collected round it in a large +circle, and staring intently, presented a most ludicrous appearance. They +became extremely nervous; so that when a wooden ball, with which they were +familiar as a plaything, was accidentally moved in the straw, under which +it was partly hidden, they all instantly started away. These monkeys +behaved very differently when a dead fish, a mouse (12. I have given a +short account of their behaviour on this occasion in my 'Expression of the +Emotions in Man and Animals,' p. 43.), a living turtle, and other new +objects were placed in their cages; for though at first frightened, they +soon approached, handled and examined them. I then placed a live snake in +a paper bag, with the mouth loosely closed, in one of the larger +compartments. One of the monkeys immediately approached, cautiously opened +the bag a little, peeped in, and instantly dashed away. Then I witnessed +what Brehm has described, for monkey after monkey, with head raised high +and turned on one side, could not resist taking a momentary peep into the +upright bag, at the dreadful object lying quietly at the bottom. It would +almost appear as if monkeys had some notion of zoological affinities, for +those kept by Brehm exhibited a strange, though mistaken, instinctive dread +of innocent lizards and frogs. An orang, also, has been known to be much +alarmed at the first sight of a turtle. (13. W.C.L. Martin, 'Natural +History of Mammalia,' 1841, p. 405.) + +The principle of IMITATION is strong in man, and especially, as I have +myself observed, with savages. In certain morbid states of the brain this +tendency is exaggerated to an extraordinary degree: some hemiplegic +patients and others, at the commencement of inflammatory softening of the +brain, unconsciously imitate every word which is uttered, whether in their +own or in a foreign language, and every gesture or action which is +performed near them. (14. Dr. Bateman, 'On Aphasia,' 1870, p. 110.) +Desor (15. Quoted by Vogt, 'Mémoire sur les Microcephales,' 1867, p. 168.) +has remarked that no animal voluntarily imitates an action performed by +man, until in the ascending scale we come to monkeys, which are well known +to be ridiculous mockers. Animals, however, sometimes imitate each other's +actions: thus two species of wolves, which had been reared by dogs, +learned to bark, as does sometimes the jackal (16. The 'Variation of +Animals and Plants under Domestication,' vol. i. p. 27.), but whether this +can be called voluntary imitation is another question. Birds imitate the +songs of their parents, and sometimes of other birds; and parrots are +notorious imitators of any sound which they often hear. Dureau de la Malle +gives an account (17. 'Annales des Sciences Nat.' (1st Series), tom. xxii. +p. 397.) of a dog reared by a cat, who learnt to imitate the well-known +action of a cat licking her paws, and thus washing her ears and face; this +was also witnessed by the celebrated naturalist Audouin. I have received +several confirmatory accounts; in one of these, a dog had not been suckled +by a cat, but had been brought up with one, together with kittens, and had +thus acquired the above habit, which he ever afterwards practised during +his life of thirteen years. Dureau de la Malle's dog likewise learnt from +the kittens to play with a ball by rolling it about with his fore paws, and +springing on it. A correspondent assures me that a cat in his house used +to put her paws into jugs of milk having too narrow a mouth for her head. +A kitten of this cat soon learned the same trick, and practised it ever +afterwards, whenever there was an opportunity. + +The parents of many animals, trusting to the principle of imitation in +their young, and more especially to their instinctive or inherited +tendencies, may be said to educate them. We see this when a cat brings a +live mouse to her kittens; and Dureau de la Malle has given a curious +account (in the paper above quoted) of his observations on hawks which +taught their young dexterity, as well as judgment of distances, by first +dropping through the air dead mice and sparrows, which the young generally +failed to catch, and then bringing them live birds and letting them loose. + +Hardly any faculty is more important for the intellectual progress of man +than ATTENTION. Animals clearly manifest this power, as when a cat watches +by a hole and prepares to spring on its prey. Wild animals sometimes +become so absorbed when thus engaged, that they may be easily approached. +Mr. Bartlett has given me a curious proof how variable this faculty is in +monkeys. A man who trains monkeys to act in plays, used to purchase common +kinds from the Zoological Society at the price of five pounds for each; but +he offered to give double the price, if he might keep three or four of them +for a few days, in order to select one. When asked how he could possibly +learn so soon, whether a particular monkey would turn out a good actor, he +answered that it all depended on their power of attention. If when he was +talking and explaining anything to a monkey, its attention was easily +distracted, as by a fly on the wall or other trifling object, the case was +hopeless. If he tried by punishment to make an inattentive monkey act, it +turned sulky. On the other hand, a monkey which carefully attended to him +could always be trained. + +It is almost superfluous to state that animals have excellent MEMORIES for +persons and places. A baboon at the Cape of Good Hope, as I have been +informed by Sir Andrew Smith, recognised him with joy after an absence of +nine months. I had a dog who was savage and averse to all strangers, and I +purposely tried his memory after an absence of five years and two days. I +went near the stable where he lived, and shouted to him in my old manner; +he shewed no joy, but instantly followed me out walking, and obeyed me, +exactly as if I had parted with him only half an hour before. A train of +old associations, dormant during five years, had thus been instantaneously +awakened in his mind. Even ants, as P. Huber (18. 'Les Moeurs des +Fourmis,' 1810, p. 150.) has clearly shewn, recognised their fellow-ants +belonging to the same community after a separation of four months. Animals +can certainly by some means judge of the intervals of time between +recurrent events. + +The IMAGINATION is one of the highest prerogatives of man. By this faculty +he unites former images and ideas, independently of the will, and thus +creates brilliant and novel results. A poet, as Jean Paul Richter remarks +(19. Quoted in Dr. Maudsley's 'Physiology and Pathology of Mind,' 1868, +pp. 19, 220.), "who must reflect whether he shall make a character say yes +or no--to the devil with him; he is only a stupid corpse." Dreaming gives +us the best notion of this power; as Jean Paul again says, "The dream is an +involuntary art of poetry." The value of the products of our imagination +depends of course on the number, accuracy, and clearness of our +impressions, on our judgment and taste in selecting or rejecting the +involuntary combinations, and to a certain extent on our power of +voluntarily combining them. As dogs, cats, horses, and probably all the +higher animals, even birds (20. Dr. Jerdon, 'Birds of India,' vol. i. +1862, p. xxi. Houzeau says that his parokeets and canary-birds dreamt: +'Etudes sur les Facultes Mentales des Animaux,' tom. ii. p. 136.) have +vivid dreams, and this is shewn by their movements and the sounds uttered, +we must admit that they possess some power of imagination. There must be +something special, which causes dogs to howl in the night, and especially +during moonlight, in that remarkable and melancholy manner called baying. +All dogs do not do so; and, according to Houzeau (21. ibid. 1872, tom. ii. +p. 181.), they do not then look at the moon, but at some fixed point near +the horizon. Houzeau thinks that their imaginations are disturbed by the +vague outlines of the surrounding objects, and conjure up before them +fantastic images: if this be so, their feelings may almost be called +superstitious. + +Of all the faculties of the human mind, it will, I presume, be admitted +that REASON stands at the summit. Only a few persons now dispute that +animals possess some power of reasoning. Animals may constantly be seen to +pause, deliberate, and resolve. It is a significant fact, that the more +the habits of any particular animal are studied by a naturalist, the more +he attributes to reason and the less to unlearnt instincts. (22. Mr. L.H. +Morgan's work on 'The American Beaver,' 1868, offers a good illustration of +this remark. I cannot help thinking, however, that he goes too far in +underrating the power of instinct.) In future chapters we shall see that +some animals extremely low in the scale apparently display a certain amount +of reason. No doubt it is often difficult to distinguish between the power +of reason and that of instinct. For instance, Dr. Hayes, in his work on +'The Open Polar Sea,' repeatedly remarks that his dogs, instead of +continuing to draw the sledges in a compact body, diverged and separated +when they came to thin ice, so that their weight might be more evenly +distributed. This was often the first warning which the travellers +received that the ice was becoming thin and dangerous. Now, did the dogs +act thus from the experience of each individual, or from the example of the +older and wiser dogs, or from an inherited habit, that is from instinct? +This instinct, may possibly have arisen since the time, long ago, when dogs +were first employed by the natives in drawing their sledges; or the Arctic +wolves, the parent-stock of the Esquimaux dog, may have acquired an +instinct impelling them not to attack their prey in a close pack, when on +thin ice. + +We can only judge by the circumstances under which actions are performed, +whether they are due to instinct, or to reason, or to the mere association +of ideas: this latter principle, however, is intimately connected with +reason. A curious case has been given by Prof. Mobius (23. 'Die +Bewegungen der Thiere,' etc., 1873, p. 11.), of a pike, separated by a +plate of glass from an adjoining aquarium stocked with fish, and who often +dashed himself with such violence against the glass in trying to catch the +other fishes, that he was sometimes completely stunned. The pike went on +thus for three months, but at last learnt caution, and ceased to do so. +The plate of glass was then removed, but the pike would not attack these +particular fishes, though he would devour others which were afterwards +introduced; so strongly was the idea of a violent shock associated in his +feeble mind with the attempt on his former neighbours. If a savage, who +had never seen a large plate-glass window, were to dash himself even once +against it, he would for a long time afterwards associate a shock with a +window-frame; but very differently from the pike, he would probably reflect +on the nature of the impediment, and be cautious under analogous +circumstances. Now with monkeys, as we shall presently see, a painful or +merely a disagreeable impression, from an action once performed, is +sometimes sufficient to prevent the animal from repeating it. If we +attribute this difference between the monkey and the pike solely to the +association of ideas being so much stronger and more persistent in the one +than the other, though the pike often received much the more severe injury, +can we maintain in the case of man that a similar difference implies the +possession of a fundamentally different mind? + +Houzeau relates (24. 'Études sur les Facultés Mentales des Animaux,' 1872, +tom. ii. p. 265.) that, whilst crossing a wide and arid plain in Texas, his +two dogs suffered greatly from thirst, and that between thirty and forty +times they rushed down the hollows to search for water. These hollows were +not valleys, and there were no trees in them, or any other difference in +the vegetation, and as they were absolutely dry there could have been no +smell of damp earth. The dogs behaved as if they knew that a dip in the +ground offered them the best chance of finding water, and Houzeau has often +witnessed the same behaviour in other animals. + +I have seen, as I daresay have others, that when a small object is thrown +on the ground beyond the reach of one of the elephants in the Zoological +Gardens, he blows through his trunk on the ground beyond the object, so +that the current reflected on all sides may drive the object within his +reach. Again a well-known ethnologist, Mr. Westropp, informs me that he +observed in Vienna a bear deliberately making with his paw a current in +some water, which was close to the bars of his cage, so as to draw a piece +of floating bread within his reach. These actions of the elephant and bear +can hardly be attributed to instinct or inherited habit, as they would be +of little use to an animal in a state of nature. Now, what is the +difference between such actions, when performed by an uncultivated man, and +by one of the higher animals? + +The savage and the dog have often found water at a low level, and the +coincidence under such circumstances has become associated in their minds. +A cultivated man would perhaps make some general proposition on the +subject; but from all that we know of savages it is extremely doubtful +whether they would do so, and a dog certainly would not. But a savage, as +well as a dog, would search in the same way, though frequently +disappointed; and in both it seems to be equally an act of reason, whether +or not any general proposition on the subject is consciously placed before +the mind. (25. Prof. Huxley has analysed with admirable clearness the +mental steps by which a man, as well as a dog, arrives at a conclusion in a +case analogous to that given in my text. See his article, 'Mr. Darwin's +Critics,' in the 'Contemporary Review,' Nov. 1871, p. 462, and in his +'Critiques and Essays,' 1873, p. 279.) The same would apply to the +elephant and the bear making currents in the air or water. The savage +would certainly neither know nor care by what law the desired movements +were effected; yet his act would be guided by a rude process of reasoning, +as surely as would a philosopher in his longest chain of deductions. There +would no doubt be this difference between him and one of the higher +animals, that he would take notice of much slighter circumstances and +conditions, and would observe any connection between them after much less +experience, and this would be of paramount importance. I kept a daily +record of the actions of one of my infants, and when he was about eleven +months old, and before he could speak a single word, I was continually +struck with the greater quickness, with which all sorts of objects and +sounds were associated together in his mind, compared with that of the most +intelligent dogs I ever knew. But the higher animals differ in exactly the +same way in this power of association from those low in the scale, such as +the pike, as well as in that of drawing inferences and of observation. + +The promptings of reason, after very short experience, are well shewn by +the following actions of American monkeys, which stand low in their order. +Rengger, a most careful observer, states that when he first gave eggs to +his monkeys in Paraguay, they smashed them, and thus lost much of their +contents; afterwards they gently hit one end against some hard body, and +picked off the bits of shell with their fingers. After cutting themselves +only ONCE with any sharp tool, they would not touch it again, or would +handle it with the greatest caution. Lumps of sugar were often given them +wrapped up in paper; and Rengger sometimes put a live wasp in the paper, so +that in hastily unfolding it they got stung; after this had ONCE happened, +they always first held the packet to their ears to detect any movement +within. (26. Mr. Belt, in his most interesting work, 'The Naturalist in +Nicaragua,' 1874, (p. 119,) likewise describes various actions of a tamed +Cebus, which, I think, clearly shew that this animal possessed some +reasoning power.) + +The following cases relate to dogs. Mr. Colquhoun (27. 'The Moor and the +Loch,' p. 45. Col. Hutchinson on 'Dog Breaking,' 1850, p. 46.) winged two +wild-ducks, which fell on the further side of a stream; his retriever tried +to bring over both at once, but could not succeed; she then, though never +before known to ruffle a feather, deliberately killed one, brought over the +other, and returned for the dead bird. Col. Hutchinson relates that two +partridges were shot at once, one being killed, the other wounded; the +latter ran away, and was caught by the retriever, who on her return came +across the dead bird; "she stopped, evidently greatly puzzled, and after +one or two trials, finding she could not take it up without permitting the +escape of the winged bird, she considered a moment, then deliberately +murdered it by giving it a severe crunch, and afterwards brought away both +together. This was the only known instance of her ever having wilfully +injured any game." Here we have reason though not quite perfect, for the +retriever might have brought the wounded bird first and then returned for +the dead one, as in the case of the two wild-ducks. I give the above +cases, as resting on the evidence of two independent witnesses, and because +in both instances the retrievers, after deliberation, broke through a habit +which is inherited by them (that of not killing the game retrieved), and +because they shew how strong their reasoning faculty must have been to +overcome a fixed habit. + +I will conclude by quoting a remark by the illustrious Humboldt. (28. +'Personal Narrative,' Eng. translat., vol. iii. p. 106.) "The muleteers in +S. America say, 'I will not give you the mule whose step is easiest, but la +mas racional,--the one that reasons best'"; and; as, he adds, "this popular +expression, dictated by long experience, combats the system of animated +machines, better perhaps than all the arguments of speculative philosophy." +Nevertheless some writers even yet deny that the higher animals possess a +trace of reason; and they endeavour to explain away, by what appears to be +mere verbiage, (29. I am glad to find that so acute a reasoner as Mr. +Leslie Stephen ('Darwinism and Divinity, Essays on Free Thinking,' 1873, p. +80), in speaking of the supposed impassable barrier between the minds of +man and the lower animals, says, "The distinctions, indeed, which have been +drawn, seem to us to rest upon no better foundation than a great many other +metaphysical distinctions; that is, the assumption that because you can +give two things different names, they must therefore have different +natures. It is difficult to understand how anybody who has ever kept a +dog, or seen an elephant, can have any doubt as to an animal's power of +performing the essential processes of reasoning.") all such facts as those +above given. + +It has, I think, now been shewn that man and the higher animals, especially +the Primates, have some few instincts in common. All have the same senses, +intuitions, and sensations,--similar passions, affections, and emotions, +even the more complex ones, such as jealousy, suspicion, emulation, +gratitude, and magnanimity; they practise deceit and are revengeful; they +are sometimes susceptible to ridicule, and even have a sense of humour; +they feel wonder and curiosity; they possess the same faculties of +imitation, attention, deliberation, choice, memory, imagination, the +association of ideas, and reason, though in very different degrees. The +individuals of the same species graduate in intellect from absolute +imbecility to high excellence. They are also liable to insanity, though +far less often than in the case of man. (30. See 'Madness in Animals,' by +Dr. W. Lauder Lindsay, in 'Journal of Mental Science,' July 1871.) +Nevertheless, many authors have insisted that man is divided by an +insuperable barrier from all the lower animals in his mental faculties. I +formerly made a collection of above a score of such aphorisms, but they are +almost worthless, as their wide difference and number prove the difficulty, +if not the impossibility, of the attempt. It has been asserted that man +alone is capable of progressive improvement; that he alone makes use of +tools or fire, domesticates other animals, or possesses property; that no +animal has the power of abstraction, or of forming general concepts, is +self-conscious and comprehends itself; that no animal employs language; +that man alone has a sense of beauty, is liable to caprice, has the feeling +of gratitude, mystery, etc.; believes in God, or is endowed with a +conscience. I will hazard a few remarks on the more important and +interesting of these points. + +Archbishop Sumner formerly maintained (31. Quoted by Sir C. Lyell, +'Antiquity of Man,' p. 497.) that man alone is capable of progressive +improvement. That he is capable of incomparably greater and more rapid +improvement than is any other animal, admits of no dispute; and this is +mainly due to his power of speaking and handing down his acquired +knowledge. With animals, looking first to the individual, every one who +has had any experience in setting traps, knows that young animals can he +caught much more easily than old ones; and they can be much more easily +approached by an enemy. Even with respect to old animals, it is impossible +to catch many in the same place and in the same kind of trap, or to destroy +them by the same kind of poison; yet it is improbable that all should have +partaken of the poison, and impossible that all should have been caught in +a trap. They must learn caution by seeing their brethren caught or +poisoned. In North America, where the fur-bearing animals have long been +pursued, they exhibit, according to the unanimous testimony of all +observers, an almost incredible amount of sagacity, caution and cunning; +but trapping has been there so long carried on, that inheritance may +possibly have come into play. I have received several accounts that when +telegraphs are first set up in any district, many birds kill themselves by +flying against the wires, but that in the course of a very few years they +learn to avoid this danger, by seeing, as it would appear, their comrades +killed. (32. For additional evidence, with details, see M. Houzeau, +'Études sur les Facultés Mentales des Animaux,' tom. ii. 1872, p. 147.) + +If we look to successive generations, or to the race, there is no doubt +that birds and other animals gradually both acquire and lose caution in +relation to man or other enemies (33. See, with respect to birds on +oceanic islands, my 'Journal of Researches during the Voyage of the +"Beagle,"' 1845, p. 398. 'Origin of Species,' 5th ed. p. 260.); and this +caution is certainly in chief part an inherited habit or instinct, but in +part the result of individual experience. A good observer, Leroy (34. +'Lettres Phil. sur l'Intelligence des Animaux,' nouvelle edit., 1802, p. +86.), states, that in districts where foxes are much hunted, the young, on +first leaving their burrows, are incontestably much more wary than the old +ones in districts where they are not much disturbed. + +Our domestic dogs are descended from wolves and jackals (35. See the +evidence on this head in chap. i. vol. i., 'On the Variation of Animals and +Plants under Domestication.'), and though they may not have gained in +cunning, and may have lost in wariness and suspicion, yet they have +progressed in certain moral qualities, such as in affection, trust- +worthiness, temper, and probably in general intelligence. The common rat +has conquered and beaten several other species throughout Europe, in parts +of North America, New Zealand, and recently in Formosa, as well as on the +mainland of China. Mr. Swinhoe (36. 'Proceedings Zoological Society,' +1864, p. 186.), who describes these two latter cases, attributes the +victory of the common rat over the large Mus coninga to its superior +cunning; and this latter quality may probably be attributed to the habitual +exercise of all its faculties in avoiding extirpation by man, as well as to +nearly all the less cunning or weak-minded rats having been continuously +destroyed by him. It is, however, possible that the success of the common +rat may be due to its having possessed greater cunning than its fellow- +species, before it became associated with man. To maintain, independently +of any direct evidence, that no animal during the course of ages has +progressed in intellect or other mental faculties, is to beg the question +of the evolution of species. We have seen that, according to Lartet, +existing mammals belonging to several orders have larger brains than their +ancient tertiary prototypes. + +It has often been said that no animal uses any tool; but the chimpanzee in +a state of nature cracks a native fruit, somewhat like a walnut, with a +stone. (37. Savage and Wyman in 'Boston Journal of Natural History,' vol. +iv. 1843-44, p. 383.) Rengger (38. 'Säugethiere von Paraguay,' 1830, s. +51-56.) easily taught an American monkey thus to break open hard palm-nuts; +and afterwards of its own accord, it used stones to open other kinds of +nuts, as well as boxes. It thus also removed the soft rind of fruit that +had a disagreeable flavour. Another monkey was taught to open the lid of a +large box with a stick, and afterwards it used the stick as a lever to move +heavy bodies; and I have myself seen a young orang put a stick into a +crevice, slip his hand to the other end, and use it in the proper manner as +a lever. The tamed elephants in India are well known to break off branches +of trees and use them to drive away the flies; and this same act has been +observed in an elephant in a state of nature. (39. The Indian Field, +March 4, 1871.) I have seen a young orang, when she thought she was going +to be whipped, cover and protect herself with a blanket or straw. In these +several cases stones and sticks were employed as implements; but they are +likewise used as weapons. Brehm (40. 'Thierleben,' B. i. s. 79, 82.) +states, on the authority of the well-known traveller Schimper, that in +Abyssinia when the baboons belonging to one species (C. gelada) descend in +troops from the mountains to plunder the fields, they sometimes encounter +troops of another species (C. hamadryas), and then a fight ensues. The +Geladas roll down great stones, which the Hamadryas try to avoid, and then +both species, making a great uproar, rush furiously against each other. +Brehm, when accompanying the Duke of Coburg-Gotha, aided in an attack with +fire-arms on a troop of baboons in the pass of Mensa in Abyssinia. The +baboons in return rolled so many stones down the mountain, some as large as +a man's head, that the attackers had to beat a hasty retreat; and the pass +was actually closed for a time against the caravan. It deserves notice +that these baboons thus acted in concert. Mr. Wallace (41. 'The Malay +Archipelago,' vol. i. 1869, p. 87.) on three occasions saw female orangs, +accompanied by their young, "breaking off branches and the great spiny +fruit of the Durian tree, with every appearance of rage; causing such a +shower of missiles as effectually kept us from approaching too near the +tree." As I have repeatedly seen, a chimpanzee will throw any object at +hand at a person who offends him; and the before-mentioned baboon at the +Cape of Good Hope prepared mud for the purpose. + +In the Zoological Gardens, a monkey, which had weak teeth, used to break +open nuts with a stone; and I was assured by the keepers that after using +the stone, he hid it in the straw, and would not let any other monkey touch +it. Here, then, we have the idea of property; but this idea is common to +every dog with a bone, and to most or all birds with their nests. + +The Duke of Argyll (42. 'Primeval Man,' 1869, pp. 145, 147.) remarks, that +the fashioning of an implement for a special purpose is absolutely peculiar +to man; and he considers that this forms an immeasurable gulf between him +and the brutes. This is no doubt a very important distinction; but there +appears to me much truth in Sir J. Lubbock's suggestion (43. 'Prehistoric +Times,' 1865, p. 473, etc.), that when primeval man first used flint-stones +for any purpose, he would have accidentally splintered them, and would then +have used the sharp fragments. From this step it would be a small one to +break the flints on purpose, and not a very wide step to fashion them +rudely. This latter advance, however, may have taken long ages, if we may +judge by the immense interval of time which elapsed before the men of the +neolithic period took to grinding and polishing their stone tools. In +breaking the flints, as Sir J. Lubbock likewise remarks, sparks would have +been emitted, and in grinding them heat would have been evolved: thus the +two usual methods of "obtaining fire may have originated." The nature of +fire would have been known in the many volcanic regions where lava +occasionally flows through forests. The anthropomorphous apes, guided +probably by instinct, build for themselves temporary platforms; but as many +instincts are largely controlled by reason, the simpler ones, such as this +of building a platform, might readily pass into a voluntary and conscious +act. The orang is known to cover itself at night with the leaves of the +Pandanus; and Brehm states that one of his baboons used to protect itself +from the heat of the sun by throwing a straw-mat over its head. In these +several habits, we probably see the first steps towards some of the simpler +arts, such as rude architecture and dress, as they arose amongst the early +progenitors of man. + +ABSTRACTION, GENERAL CONCEPTIONS, SELF-CONSCIOUSNESS, MENTAL INDIVIDUALITY. + +It would be very difficult for any one with even much more knowledge than I +possess, to determine how far animals exhibit any traces of these high +mental powers. This difficulty arises from the impossibility of judging +what passes through the mind of an animal; and again, the fact that writers +differ to a great extent in the meaning which they attribute to the above +terms, causes a further difficulty. If one may judge from various articles +which have been published lately, the greatest stress seems to be laid on +the supposed entire absence in animals of the power of abstraction, or of +forming general concepts. But when a dog sees another dog at a distance, +it is often clear that he perceives that it is a dog in the abstract; for +when he gets nearer his whole manner suddenly changes, if the other dog be +a friend. A recent writer remarks, that in all such cases it is a pure +assumption to assert that the mental act is not essentially of the same +nature in the animal as in man. If either refers what he perceives with +his senses to a mental concept, then so do both. (44. Mr. Hookham, in a +letter to Prof. Max Muller, in the 'Birmingham News,' May 1873.) When I +say to my terrier, in an eager voice (and I have made the trial many +times), "Hi, hi, where is it?" she at once takes it as a sign that +something is to be hunted, and generally first looks quickly all around, +and then rushes into the nearest thicket, to scent for any game, but +finding nothing, she looks up into any neighbouring tree for a squirrel. +Now do not these actions clearly shew that she had in her mind a general +idea or concept that some animal is to be discovered and hunted? + +It may be freely admitted that no animal is self-conscious, if by this term +it is implied, that he reflects on such points, as whence he comes or +whither he will go, or what is life and death, and so forth. But how can +we feel sure that an old dog with an excellent memory and some power of +imagination, as shewn by his dreams, never reflects on his past pleasures +or pains in the chase? And this would be a form of self-consciousness. On +the other hand, as Buchner (45. 'Conférences sur la Théorie Darwinienne,' +French translat. 1869, p. 132.) has remarked, how little can the hard- +worked wife of a degraded Australian savage, who uses very few abstract +words, and cannot count above four, exert her self-consciousness, or +reflect on the nature of her own existence. It is generally admitted, that +the higher animals possess memory, attention, association, and even some +imagination and reason. If these powers, which differ much in different +animals, are capable of improvement, there seems no great improbability in +more complex faculties, such as the higher forms of abstraction, and self- +consciousness, etc., having been evolved through the development and +combination of the simpler ones. It has been urged against the views here +maintained that it is impossible to say at what point in the ascending +scale animals become capable of abstraction, etc.; but who can say at what +age this occurs in our young children? We see at least that such powers +are developed in children by imperceptible degrees. + +That animals retain their mental individuality is unquestionable. When my +voice awakened a train of old associations in the mind of the before- +mentioned dog, he must have retained his mental individuality, although +every atom of his brain had probably undergone change more than once during +the interval of five years. This dog might have brought forward the +argument lately advanced to crush all evolutionists, and said, "I abide +amid all mental moods and all material changes...The teaching that atoms +leave their impressions as legacies to other atoms falling into the places +they have vacated is contradictory of the utterance of consciousness, and +is therefore false; but it is the teaching necessitated by evolutionism, +consequently the hypothesis is a false one." (46. The Rev. Dr. J. M'Cann, +'Anti-Darwinism,' 1869, p. 13.) + +LANGUAGE. + +This faculty has justly been considered as one of the chief distinctions +between man and the lower animals. But man, as a highly competent judge, +Archbishop Whately remarks, "is not the only animal that can make use of +language to express what is passing in his mind, and can understand, more +or less, what is so expressed by another." (47. Quoted in +'Anthropological Review,' 1864, p. 158.) In Paraguay the Cebus azarae when +excited utters at least six distinct sounds, which excite in other monkeys +similar emotions. (48. Rengger, ibid. s. 45.) The movements of the +features and gestures of monkeys are understood by us, and they partly +understand ours, as Rengger and others declare. It is a more remarkable +fact that the dog, since being domesticated, has learnt to bark (49. See +my 'Variation of Animals and Plants under Domestication,' vol. i. p. 27.) +in at least four or five distinct tones. Although barking is a new art, no +doubt the wild parent-species of the dog expressed their feelings by cries +of various kinds. With the domesticated dog we have the bark of eagerness, +as in the chase; that of anger, as well as growling; the yelp or howl of +despair, as when shut up; the baying at night; the bark of joy, as when +starting on a walk with his master; and the very distinct one of demand or +supplication, as when wishing for a door or window to be opened. According +to Houzeau, who paid particular attention to the subject, the domestic fowl +utters at least a dozen significant sounds. (50. 'Facultés Mentales des +Animaux,' tom. ii. 1872, p. 346-349.) + +The habitual use of articulate language is, however, peculiar to man; but +he uses, in common with the lower animals, inarticulate cries to express +his meaning, aided by gestures and the movements of the muscles of the +face. (51. See a discussion on this subject in Mr. E.B. Tylor's very +interesting work, 'Researches into the Early History of Mankind,' 1865, +chaps. ii. to iv.) This especially holds good with the more simple and +vivid feelings, which are but little connected with our higher +intelligence. Our cries of pain, fear, surprise, anger, together with +their appropriate actions, and the murmur of a mother to her beloved child +are more expressive than any words. That which distinguishes man from the +lower animals is not the understanding of articulate sounds, for, as every +one knows, dogs understand many words and sentences. In this respect they +are at the same stage of development as infants, between the ages of ten +and twelve months, who understand many words and short sentences, but +cannot yet utter a single word. It is not the mere articulation which is +our distinguishing character, for parrots and other birds possess this +power. Nor is it the mere capacity of connecting definite sounds with +definite ideas; for it is certain that some parrots, which have been taught +to speak, connect unerringly words with things, and persons with events. +(52. I have received several detailed accounts to this effect. Admiral +Sir B.J. Sulivan, whom I know to be a careful observer, assures me that an +African parrot, long kept in his father's house, invariably called certain +persons of the household, as well as visitors, by their names. He said +"good morning" to every one at breakfast, and "good night" to each as they +left the room at night, and never reversed these salutations. To Sir B.J. +Sulivan's father, he used to add to the " good morning" a short sentence, +which was never once repeated after his father's death. He scolded +violently a strange dog which came into the room through the open window; +and he scolded another parrot (saying "you naughty polly") which had got +out of its cage, and was eating apples on the kitchen table. See also, to +the same effect, Houzeau on parrots, 'Facultés Mentales,' tom. ii. p. 309. +Dr. A. Moschkau informs me that he knew a starling which never made a +mistake in saying in German "good morning" to persons arriving, and "good +bye, old fellow," to those departing. I could add several other such +cases.) The lower animals differ from man solely in his almost infinitely +larger power of associating together the most diversified sounds and ideas; +and this obviously depends on the high development of his mental powers. + +As Horne Tooke, one of the founders of the noble science of philology, +observes, language is an art, like brewing or baking; but writing would +have been a better simile. It certainly is not a true instinct, for every +language has to be learnt. It differs, however, widely from all ordinary +arts, for man has an instinctive tendency to speak, as we see in the babble +of our young children; whilst no child has an instinctive tendency to brew, +bake, or write. Moreover, no philologist now supposes that any language +has been deliberately invented; it has been slowly and unconsciously +developed by many steps. (53. See some good remarks on this head by Prof. +Whitney, in his 'Oriental and Linguistic Studies,' 1873, p. 354. He +observes that the desire of communication between man is the living force, +which, in the development of language, "works both consciously and +unconsciously; consciously as regards the immediate end to be attained; +unconsciously as regards the further consequences of the act.") The sounds +uttered by birds offer in several respects the nearest analogy to language, +for all the members of the same species utter the same instinctive cries +expressive of their emotions; and all the kinds which sing, exert their +power instinctively; but the actual song, and even the call-notes, are +learnt from their parents or foster-parents. These sounds, as Daines +Barrington (54. Hon. Daines Barrington in 'Philosoph. Transactions,' 1773, +p. 262. See also Dureau de la Malle, in 'Ann. des. Sc. Nat.' 3rd series, +Zoolog., tom. x. p. 119.) has proved, "are no more innate than language is +in man." The first attempts to sing "may be compared to the imperfect +endeavour in a child to babble." The young males continue practising, or +as the bird-catchers say, "recording," for ten or eleven months. Their +first essays shew hardly a rudiment of the future song; but as they grow +older we can perceive what they are aiming at; and at last they are said +"to sing their song round." Nestlings which have learnt the song of a +distinct species, as with the canary-birds educated in the Tyrol, teach and +transmit their new song to their offspring. The slight natural differences +of song in the same species inhabiting different districts may be +appositely compared, as Barrington remarks, "to provincial dialects"; and +the songs of allied, though distinct species may be compared with the +languages of distinct races of man. I have given the foregoing details to +shew that an instinctive tendency to acquire an art is not peculiar to man. + +With respect to the origin of articulate language, after having read on the +one side the highly interesting works of Mr. Hensleigh Wedgwood, the Rev. +F. Farrar, and Prof. Schleicher (55. 'On the Origin of Language,' by H. +Wedgwood, 1866. 'Chapters on Language,' by the Rev. F.W. Farrar, 1865. +These works are most interesting. See also 'De la Phys. et de Parole,' par +Albert Lemoine, 1865, p. 190. The work on this subject, by the late Prof. +Aug. Schleicher, has been translated by Dr. Bikkers into English, under the +title of 'Darwinism tested by the Science of Language,' 1869.), and the +celebrated lectures of Prof. Max Muller on the other side, I cannot doubt +that language owes its origin to the imitation and modification of various +natural sounds, the voices of other animals, and man's own instinctive +cries, aided by signs and gestures. When we treat of sexual selection we +shall see that primeval man, or rather some early progenitor of man, +probably first used his voice in producing true musical cadences, that is +in singing, as do some of the gibbon-apes at the present day; and we may +conclude from a widely-spread analogy, that this power would have been +especially exerted during the courtship of the sexes,--would have expressed +various emotions, such as love, jealousy, triumph,--and would have served +as a challenge to rivals. It is, therefore, probable that the imitation of +musical cries by articulate sounds may have given rise to words expressive +of various complex emotions. The strong tendency in our nearest allies, +the monkeys, in microcephalous idiots (56. Vogt, 'Mémoire sur les +Microcephales,' 1867, p. 169. With respect to savages, I have given some +facts in my 'Journal of Researches,' etc., 1845, p. 206.), and in the +barbarous races of mankind, to imitate whatever they hear deserves notice, +as bearing on the subject of imitation. Since monkeys certainly understand +much that is said to them by man, and when wild, utter signal-cries of +danger to their fellows (57. See clear evidence on this head in the two +works so often quoted, by Brehm and Rengger.); and since fowls give +distinct warnings for danger on the ground, or in the sky from hawks (both, +as well as a third cry, intelligible to dogs) (58. Houzeau gives a very +curious account of his observations on this subject in his 'Facultés +Mentales des Animaux,' tom. ii. p. 348.), may not some unusually wise ape- +like animal have imitated the growl of a beast of prey, and thus told his +fellow-monkeys the nature of the expected danger? This would have been a +first step in the formation of a language. + +As the voice was used more and more, the vocal organs would have been +strengthened and perfected through the principle of the inherited effects +of use; and this would have reacted on the power of speech. But the +relation between the continued use of language and the development of the +brain, has no doubt been far more important. The mental powers in some +early progenitor of man must have been more highly developed than in any +existing ape, before even the most imperfect form of speech could have come +into use; but we may confidently believe that the continued use and +advancement of this power would have reacted on the mind itself, by +enabling and encouraging it to carry on long trains of thought. A complex +train of thought can no more be carried on without the aid of words, +whether spoken or silent, than a long calculation without the use of +figures or algebra. It appears, also, that even an ordinary train of +thought almost requires, or is greatly facilitated by some form of +language, for the dumb, deaf, and blind girl, Laura Bridgman, was observed +to use her fingers whilst dreaming. (59. See remarks on this head by Dr. +Maudsley, 'The Physiology and Pathology of Mind,' 2nd ed., 1868, p. 199.) +Nevertheless, a long succession of vivid and connected ideas may pass +through the mind without the aid of any form of language, as we may infer +from the movements of dogs during their dreams. We have, also, seen that +animals are able to reason to a certain extent, manifestly without the aid +of language. The intimate connection between the brain, as it is now +developed in us, and the faculty of speech, is well shewn by those curious +cases of brain-disease in which speech is specially affected, as when the +power to remember substantives is lost, whilst other words can be correctly +used, or where substantives of a certain class, or all except the initial +letters of substantives and proper names are forgotten. (60. Many curious +cases have been recorded. See, for instance, Dr. Bateman 'On Aphasia,' +1870, pp. 27, 31, 53, 100, etc. Also, 'Inquiries Concerning the +Intellectual Powers,' by Dr. Abercrombie, 1838, p. 150.) There is no more +improbability in the continued use of the mental and vocal organs leading +to inherited changes in their structure and functions, than in the case of +hand-writing, which depends partly on the form of the hand and partly on +the disposition of the mind; and handwriting is certainly inherited. (61. +'The Variation of Animals and Plants under Domestication,' vol. ii. p. 6.' + +Several writers, more especially Prof. Max Muller (62. Lectures on 'Mr. +Darwin's Philosophy of Language,' 1873.), have lately insisted that the use +of language implies the power of forming general concepts; and that as no +animals are supposed to possess this power, an impassable barrier is formed +between them and man. (63. The judgment of a distinguished philologist, +such as Prof. Whitney, will have far more weight on this point than +anything that I can say. He remarks ('Oriental and Linguistic Studies,' +1873, p. 297), in speaking of Bleek's views: "Because on the grand scale +language is the necessary auxiliary of thought, indispensable to the +development of the power of thinking, to the distinctness and variety and +complexity of cognitions to the full mastery of consciousness; therefore he +would fain make thought absolutely impossible without speech, identifying +the faculty with its instrument. He might just as reasonably assert that +the human hand cannot act without a tool. With such a doctrine to start +from, he cannot stop short of Max Muller's worst paradoxes, that an infant +(in fans, not speaking) is not a human being, and that deaf-mutes do not +become possessed of reason until they learn to twist their fingers into +imitation of spoken words." Max Muller gives in italics ('Lectures on Mr. +Darwin's Philosophy of Language,' 1873, third lecture) this aphorism: +"There is no thought without words, as little as there are words without +thought." What a strange definition must here be given to the word +thought!) With respect to animals, I have already endeavoured to shew that +they have this power, at least in a rude and incipient degree. As far as +concerns infants of from ten to eleven months old, and deaf-mutes, it seems +to me incredible, that they should be able to connect certain sounds with +certain general ideas as quickly as they do, unless such ideas were already +formed in their minds. The same remark may be extended to the more +intelligent animals; as Mr. Leslie Stephen observes (64. 'Essays on Free +Thinking,' etc., 1873, p. 82.), "A dog frames a general concept of cats or +sheep, and knows the corresponding words as well as a philosopher. And the +capacity to understand is as good a proof of vocal intelligence, though in +an inferior degree, as the capacity to speak." + +Why the organs now used for speech should have been originally perfected +for this purpose, rather than any other organs, it is not difficult to see. +Ants have considerable powers of intercommunication by means of their +antennae, as shewn by Huber, who devotes a whole chapter to their language. +We might have used our fingers as efficient instruments, for a person with +practice can report to a deaf man every word of a speech rapidly delivered +at a public meeting; but the loss of our hands, whilst thus employed, would +have been a serious inconvenience. As all the higher mammals possess vocal +organs, constructed on the same general plan as ours, and used as a means +of communication, it was obviously probable that these same organs would be +still further developed if the power of communication had to be improved; +and this has been effected by the aid of adjoining and well adapted parts, +namely the tongue and lips. (65. See some good remarks to this effect by +Dr. Maudsley, 'The Physiology and Pathology of Mind,' 1868, p. 199.) The +fact of the higher apes not using their vocal organs for speech, no doubt +depends on their intelligence not having been sufficiently advanced. The +possession by them of organs, which with long-continued practice might have +been used for speech, although not thus used, is paralleled by the case of +many birds which possess organs fitted for singing, though they never sing. +Thus, the nightingale and crow have vocal organs similarly constructed, +these being used by the former for diversified song, and by the latter only +for croaking. (66. Macgillivray, 'Hist. of British Birds,' vol. ii. 1839, +p. 29. An excellent observer, Mr. Blackwall, remarks that the magpie +learns to pronounce single words, and even short sentences, more readily +than almost any other British bird; yet, as he adds, after long and closely +investigating its habits, he has never known it, in a state of nature, +display any unusual capacity for imitation. 'Researches in Zoology,' 1834, +p. 158.) If it be asked why apes have not had their intellects developed +to the same degree as that of man, general causes only can be assigned in +answer, and it is unreasonable to expect any thing more definite, +considering our ignorance with respect to the successive stages of +development through which each creature has passed. + +The formation of different languages and of distinct species, and the +proofs that both have been developed through a gradual process, are +curiously parallel. (67. See the very interesting parallelism between the +development of species and languages, given by Sir C. Lyell in 'The +Geological Evidences of the Antiquity of Man,' 1863, chap. xxiii.) But we +can trace the formation of many words further back than that of species, +for we can perceive how they actually arose from the imitation of various +sounds. We find in distinct languages striking homologies due to community +of descent, and analogies due to a similar process of formation. The +manner in which certain letters or sounds change when others change is very +like correlated growth. We have in both cases the reduplication of parts, +the effects of long-continued use, and so forth. The frequent presence of +rudiments, both in languages and in species, is still more remarkable. The +letter m in the word am, means I; so that in the expression I am, a +superfluous and useless rudiment has been retained. In the spelling also +of words, letters often remain as the rudiments of ancient forms of +pronunciation. Languages, like organic beings, can be classed in groups +under groups; and they can be classed either naturally according to +descent, or artificially by other characters. Dominant languages and +dialects spread widely, and lead to the gradual extinction of other +tongues. A language, like a species, when once extinct, never, as Sir C. +Lyell remarks, reappears. The same language never has two birth-places. +Distinct languages may be crossed or blended together. (68. See remarks +to this effect by the Rev. F.W. Farrar, in an interesting article, entitled +'Philology and Darwinism,' in 'Nature,' March 24th, 1870, p. 528.) We see +variability in every tongue, and new words are continually cropping up; but +as there is a limit to the powers of the memory, single words, like whole +languages, gradually become extinct. As Max Muller (69. 'Nature,' January +6th, 1870, p. 257.) has well remarked:--"A struggle for life is constantly +going on amongst the words and grammatical forms in each language. The +better, the shorter, the easier forms are constantly gaining the upper +hand, and they owe their success to their own inherent virtue." To these +more important causes of the survival of certain words, mere novelty and +fashion may be added; for there is in the mind of man a strong love for +slight changes in all things. The survival or preservation of certain +favoured words in the struggle for existence is natural selection. + +The perfectly regular and wonderfully complex construction of the languages +of many barbarous nations has often been advanced as a proof, either of the +divine origin of these languages, or of the high art and former +civilisation of their founders. Thus F. von Schlegel writes: "In those +languages which appear to be at the lowest grade of intellectual culture, +we frequently observe a very high and elaborate degree of art in their +grammatical structure. This is especially the case with the Basque and the +Lapponian, and many of the American languages." (70. Quoted by C.S. Wake, +'Chapters on Man,' 1868, p. 101.) But it is assuredly an error to speak of +any language as an art, in the sense of its having been elaborately and +methodically formed. Philologists now admit that conjugations, +declensions, etc., originally existed as distinct words, since joined +together; and as such words express the most obvious relations between +objects and persons, it is not surprising that they should have been used +by the men of most races during the earliest ages. With respect to +perfection, the following illustration will best shew how easily we may +err: a Crinoid sometimes consists of no less than 150,000 pieces of shell +(71. Buckland, 'Bridgewater Treatise,' p. 411.), all arranged with perfect +symmetry in radiating lines; but a naturalist does not consider an animal +of this kind as more perfect than a bilateral one with comparatively few +parts, and with none of these parts alike, excepting on the opposite sides +of the body. He justly considers the differentiation and specialisation of +organs as the test of perfection. So with languages: the most symmetrical +and complex ought not to be ranked above irregular, abbreviated, and +bastardised languages, which have borrowed expressive words and useful +forms of construction from various conquering, conquered, or immigrant +races. + +From these few and imperfect remarks I conclude that the extremely complex +and regular construction of many barbarous languages, is no proof that they +owe their origin to a special act of creation. (72. See some good remarks +on the simplification of languages, by Sir J. Lubbock, 'Origin of +Civilisation,' 1870, p. 278.) Nor, as we have seen, does the faculty of +articulate speech in itself offer any insuperable objection to the belief +that man has been developed from some lower form. + +SENSE OF BEAUTY. + +This sense has been declared to be peculiar to man. I refer here only to +the pleasure given by certain colours, forms, and sounds, and which may +fairly be called a sense of the beautiful; with cultivated men such +sensations are, however, intimately associated with complex ideas and +trains of thought. When we behold a male bird elaborately displaying his +graceful plumes or splendid colours before the female, whilst other birds, +not thus decorated, make no such display, it is impossible to doubt that +she admires the beauty of her male partner. As women everywhere deck +themselves with these plumes, the beauty of such ornaments cannot be +disputed. As we shall see later, the nests of humming-birds, and the +playing passages of bower-birds are tastefully ornamented with gaily- +coloured objects; and this shews that they must receive some kind of +pleasure from the sight of such things. With the great majority of +animals, however, the taste for the beautiful is confined, as far as we can +judge, to the attractions of the opposite sex. The sweet strains poured +forth by many male birds during the season of love, are certainly admired +by the females, of which fact evidence will hereafter be given. If female +birds had been incapable of appreciating the beautiful colours, the +ornaments, and voices of their male partners, all the labour and anxiety +exhibited by the latter in displaying their charms before the females would +have been thrown away; and this it is impossible to admit. Why certain +bright colours should excite pleasure cannot, I presume, be explained, any +more than why certain flavours and scents are agreeable; but habit has +something to do with the result, for that which is at first unpleasant to +our senses, ultimately becomes pleasant, and habits are inherited. With +respect to sounds, Helmholtz has explained to a certain extent on +physiological principles, why harmonies and certain cadences are agreeable. +But besides this, sounds frequently recurring at irregular intervals are +highly disagreeable, as every one will admit who has listened at night to +the irregular flapping of a rope on board ship. The same principle seems +to come into play with vision, as the eye prefers symmetry or figures with +some regular recurrence. Patterns of this kind are employed by even the +lowest savages as ornaments; and they have been developed through sexual +selection for the adornment of some male animals. Whether we can or not +give any reason for the pleasure thus derived from vision and hearing, yet +man and many of the lower animals are alike pleased by the same colours, +graceful shading and forms, and the same sounds. + +The taste for the beautiful, at least as far as female beauty is concerned, +is not of a special nature in the human mind; for it differs widely in the +different races of man, and is not quite the same even in the different +nations of the same race. Judging from the hideous ornaments, and the +equally hideous music admired by most savages, it might be urged that their +aesthetic faculty was not so highly developed as in certain animals, for +instance, as in birds. Obviously no animal would be capable of admiring +such scenes as the heavens at night, a beautiful landscape, or refined +music; but such high tastes are acquired through culture, and depend on +complex associations; they are not enjoyed by barbarians or by uneducated +persons. + +Many of the faculties, which have been of inestimable service to man for +his progressive advancement, such as the powers of the imagination, wonder, +curiosity, an undefined sense of beauty, a tendency to imitation, and the +love of excitement or novelty, could hardly fail to lead to capricious +changes of customs and fashions. I have alluded to this point, because a +recent writer (73. 'The Spectator,' Dec. 4th, 1869, p. 1430.) has oddly +fixed on Caprice "as one of the most remarkable and typical differences +between savages and brutes." But not only can we partially understand how +it is that man is from various conflicting influences rendered capricious, +but that the lower animals are, as we shall hereafter see, likewise +capricious in their affections, aversions, and sense of beauty. There is +also reason to suspect that they love novelty, for its own sake. + +BELIEF IN GOD--RELIGION. + +There is no evidence that man was aboriginally endowed with the ennobling +belief in the existence of an Omnipotent God. On the contrary there is +ample evidence, derived not from hasty travellers, but from men who have +long resided with savages, that numerous races have existed, and still +exist, who have no idea of one or more gods, and who have no words in their +languages to express such an idea. (74. See an excellent article on this +subject by the Rev. F.W. Farrar, in the 'Anthropological Review,' Aug. +1864, p. ccxvii. For further facts see Sir J. Lubbock, 'Prehistoric +Times,' 2nd edit., 1869, p. 564; and especially the chapters on Religion in +his 'Origin of Civilisation,' 1870.) The question is of course wholly +distinct from that higher one, whether there exists a Creator and Ruler of +the universe; and this has been answered in the affirmative by some of the +highest intellects that have ever existed. + +If, however, we include under the term "religion" the belief in unseen or +spiritual agencies, the case is wholly different; for this belief seems to +be universal with the less civilised races. Nor is it difficult to +comprehend how it arose. As soon as the important faculties of the +imagination, wonder, and curiosity, together with some power of reasoning, +had become partially developed, man would naturally crave to understand +what was passing around him, and would have vaguely speculated on his own +existence. As Mr. M'Lennan (75. 'The Worship of Animals and Plants,' in +the 'Fortnightly Review,' Oct. 1, 1869, p. 422.) has remarked, "Some +explanation of the phenomena of life, a man must feign for himself, and to +judge from the universality of it, the simplest hypothesis, and the first +to occur to men, seems to have been that natural phenomena are ascribable +to the presence in animals, plants, and things, and in the forces of +nature, of such spirits prompting to action as men are conscious they +themselves possess." It is also probable, as Mr. Tylor has shewn, that +dreams may have first given rise to the notion of spirits; for savages do +not readily distinguish between subjective and objective impressions. When +a savage dreams, the figures which appear before him are believed to have +come from a distance, and to stand over him; or "the soul of the dreamer +goes out on its travels, and comes home with a remembrance of what it has +seen." (76. Tylor, 'Early History of Mankind,' 1865, p. 6. See also the +three striking chapters on the 'Development of Religion,' in Lubbock's +'Origin of Civilisation,' 1870. In a like manner Mr. Herbert Spencer, in +his ingenious essay in the 'Fortnightly Review' (May 1st, 1870, p. 535), +accounts for the earliest forms of religious belief throughout the world, +by man being led through dreams, shadows, and other causes, to look at +himself as a double essence, corporeal and spiritual. As the spiritual +being is supposed to exist after death and to be powerful, it is +propitiated by various gifts and ceremonies, and its aid invoked. He then +further shews that names or nicknames given from some animal or other +object, to the early progenitors or founders of a tribe, are supposed after +a long interval to represent the real progenitor of the tribe; and such +animal or object is then naturally believed still to exist as a spirit, is +held sacred, and worshipped as a god. Nevertheless I cannot but suspect +that there is a still earlier and ruder stage, when anything which +manifests power or movement is thought to be endowed with some form of +life, and with mental faculties analogous to our own.) But until the +faculties of imagination, curiosity, reason, etc., had been fairly well +developed in the mind of man, his dreams would not have led him to believe +in spirits, any more than in the case of a dog. + +The tendency in savages to imagine that natural objects and agencies are +animated by spiritual or living essences, is perhaps illustrated by a +little fact which I once noticed: my dog, a full-grown and very sensible +animal, was lying on the lawn during a hot and still day; but at a little +distance a slight breeze occasionally moved an open parasol, which would +have been wholly disregarded by the dog, had any one stood near it. As it +was, every time that the parasol slightly moved, the dog growled fiercely +and barked. He must, I think, have reasoned to himself in a rapid and +unconscious manner, that movement without any apparent cause indicated the +presence of some strange living agent, and that no stranger had a right to +be on his territory. + +The belief in spiritual agencies would easily pass into the belief in the +existence of one or more gods. For savages would naturally attribute to +spirits the same passions, the same love of vengeance or simplest form of +justice, and the same affections which they themselves feel. The Fuegians +appear to be in this respect in an intermediate condition, for when the +surgeon on board the "Beagle" shot some young ducklings as specimens, York +Minster declared in the most solemn manner, "Oh, Mr. Bynoe, much rain, much +snow, blow much"; and this was evidently a retributive punishment for +wasting human food. So again he related how, when his brother killed a +"wild man," storms long raged, much rain and snow fell. Yet we could never +discover that the Fuegians believed in what we should call a God, or +practised any religious rites; and Jemmy Button, with justifiable pride, +stoutly maintained that there was no devil in his land. This latter +assertion is the more remarkable, as with savages the belief in bad spirits +is far more common than that in good ones. + +The feeling of religious devotion is a highly complex one, consisting of +love, complete submission to an exalted and mysterious superior, a strong +sense of dependence (77. See an able article on the 'Physical Elements of +Religion,' by Mr. L. Owen Pike, in 'Anthropological Review,' April 1870, p. +lxiii.), fear, reverence, gratitude, hope for the future, and perhaps other +elements. No being could experience so complex an emotion until advanced +in his intellectual and moral faculties to at least a moderately high +level. Nevertheless, we see some distant approach to this state of mind in +the deep love of a dog for his master, associated with complete submission, +some fear, and perhaps other feelings. The behaviour of a dog when +returning to his master after an absence, and, as I may add, of a monkey to +his beloved keeper, is widely different from that towards their fellows. +In the latter case the transports of joy appear to be somewhat less, and +the sense of equality is shewn in every action. Professor Braubach goes so +far as to maintain that a dog looks on his master as on a god. (78. +'Religion, Moral, etc., der Darwin'schen Art-Lehre,' 1869, s. 53. It is +said (Dr. W. Lauder Lindsay, 'Journal of Mental Science,' 1871, p. 43), +that Bacon long ago, and the poet Burns, held the same notion.) + +The same high mental faculties which first led man to believe in unseen +spiritual agencies, then in fetishism, polytheism, and ultimately in +monotheism, would infallibly lead him, as long as his reasoning powers +remained poorly developed, to various strange superstitions and customs. +Many of these are terrible to think of--such as the sacrifice of human +beings to a blood-loving god; the trial of innocent persons by the ordeal +of poison or fire; witchcraft, etc.--yet it is well occasionally to reflect +on these superstitions, for they shew us what an infinite debt of gratitude +we owe to the improvement of our reason, to science, and to our accumulated +knowledge. As Sir J. Lubbock (79. 'Prehistoric Times,' 2nd edit., p. 571. +In this work (p. 571) there will be found an excellent account of the many +strange and capricious customs of savages.) has well observed, "it is not +too much to say that the horrible dread of unknown evil hangs like a thick +cloud over savage life, and embitters every pleasure." These miserable and +indirect consequences of our highest faculties may be compared with the +incidental and occasional mistakes of the instincts of the lower animals. + + +CHAPTER IV. + +COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS--continued. + +The moral sense--Fundamental proposition--The qualities of social animals-- +Origin of sociability--Struggle between opposed instincts--Man a social +animal--The more enduring social instincts conquer other less persistent +instincts--The social virtues alone regarded by savages--The self-regarding +virtues acquired at a later stage of development--The importance of the +judgment of the members of the same community on conduct--Transmission of +moral tendencies--Summary. + +I fully subscribe to the judgment of those writers (1. See, for instance, +on this subject, Quatrefages, 'Unité de l'Espèce Humaine,' 1861, p. 21, +etc.) who maintain that of all the differences between man and the lower +animals, the moral sense or conscience is by far the most important. This +sense, as Mackintosh (2. 'Dissertation an Ethical Philosophy,' 1837, p. +231, etc.) remarks, "has a rightful supremacy over every other principle of +human action"; it is summed up in that short but imperious word "ought," so +full of high significance. It is the most noble of all the attributes of +man, leading him without a moment's hesitation to risk his life for that of +a fellow-creature; or after due deliberation, impelled simply by the deep +feeling of right or duty, to sacrifice it in some great cause. Immanuel +Kant exclaims, "Duty! Wondrous thought, that workest neither by fond +insinuation, flattery, nor by any threat, but merely by holding up thy +naked law in the soul, and so extorting for thyself always reverence, if +not always obedience; before whom all appetites are dumb, however secretly +they rebel; whence thy original?" (3. 'Metaphysics of Ethics,' translated +by J.W. Semple, Edinburgh, 1836, p. 136.) + +This great question has been discussed by many writers (4. Mr. Bain gives +a list ('Mental and Moral Science,' 1868, pp. 543-725) of twenty-six +British authors who have written on this subject, and whose names are +familiar to every reader; to these, Mr. Bain's own name, and those of Mr. +Lecky, Mr. Shadworth Hodgson, Sir J. Lubbock, and others, might be added.) +of consummate ability; and my sole excuse for touching on it, is the +impossibility of here passing it over; and because, as far as I know, no +one has approached it exclusively from the side of natural history. The +investigation possesses, also, some independent interest, as an attempt to +see how far the study of the lower animals throws light on one of the +highest psychical faculties of man. + +The following proposition seems to me in a high degree probable--namely, +that any animal whatever, endowed with well-marked social instincts (5. +Sir B. Brodie, after observing that man is a social animal ('Psychological +Enquiries,' 1854, p. 192), asks the pregnant question, "ought not this to +settle the disputed question as to the existence of a moral sense?" +Similar ideas have probably occurred to many persons, as they did long ago +to Marcus Aurelius. Mr. J.S. Mill speaks, in his celebrated work, +'Utilitarianism,' (1864, pp. 45, 46), of the social feelings as a "powerful +natural sentiment," and as "the natural basis of sentiment for utilitarian +morality." Again he says, "Like the other acquired capacities above +referred to, the moral faculty, if not a part of our nature, is a natural +out-growth from it; capable, like them, in a certain small degree of +springing up spontaneously." But in opposition to all this, he also +remarks, "if, as in my own belief, the moral feelings are not innate, but +acquired, they are not for that reason less natural." It is with +hesitation that I venture to differ at all from so profound a thinker, but +it can hardly be disputed that the social feelings are instinctive or +innate in the lower animals; and why should they not be so in man? Mr. +Bain (see, for instance, 'The Emotions and the Will,' 1865, p. 481) and +others believe that the moral sense is acquired by each individual during +his lifetime. On the general theory of evolution this is at least +extremely improbable. The ignoring of all transmitted mental qualities +will, as it seems to me, be hereafter judged as a most serious blemish in +the works of Mr. Mill.), the parental and filial affections being here +included, would inevitably acquire a moral sense or conscience, as soon as +its intellectual powers had become as well, or nearly as well developed, as +in man. For, FIRSTLY, the social instincts lead an animal to take pleasure +in the society of its fellows, to feel a certain amount of sympathy with +them, and to perform various services for them. The services may be of a +definite and evidently instinctive nature; or there may be only a wish and +readiness, as with most of the higher social animals, to aid their fellows +in certain general ways. But these feelings and services are by no means +extended to all the individuals of the same species, only to those of the +same association. SECONDLY, as soon as the mental faculties had become +highly developed, images of all past actions and motives would be +incessantly passing through the brain of each individual: and that feeling +of dissatisfaction, or even misery, which invariably results, as we shall +hereafter see, from any unsatisfied instinct, would arise, as often as it +was perceived that the enduring and always present social instinct had +yielded to some other instinct, at the time stronger, but neither enduring +in its nature, nor leaving behind it a very vivid impression. It is clear +that many instinctive desires, such as that of hunger, are in their nature +of short duration; and after being satisfied, are not readily or vividly +recalled. THIRDLY, after the power of language had been acquired, and the +wishes of the community could be expressed, the common opinion how each +member ought to act for the public good, would naturally become in a +paramount degree the guide to action. But it should be borne in mind that +however great weight we may attribute to public opinion, our regard for the +approbation and disapprobation of our fellows depends on sympathy, which, +as we shall see, forms an essential part of the social instinct, and is +indeed its foundation-stone. LASTLY, habit in the individual would +ultimately play a very important part in guiding the conduct of each +member; for the social instinct, together with sympathy, is, like any other +instinct, greatly strengthened by habit, and so consequently would be +obedience to the wishes and judgment of the community. These several +subordinate propositions must now be discussed, and some of them at +considerable length. + +It may be well first to premise that I do not wish to maintain that any +strictly social animal, if its intellectual faculties were to become as +active and as highly developed as in man, would acquire exactly the same +moral sense as ours. In the same manner as various animals have some sense +of beauty, though they admire widely-different objects, so they might have +a sense of right and wrong, though led by it to follow widely different +lines of conduct. If, for instance, to take an extreme case, men were +reared under precisely the same conditions as hive-bees, there can hardly +be a doubt that our unmarried females would, like the worker-bees, think it +a sacred duty to kill their brothers, and mothers would strive to kill +their fertile daughters; and no one would think of interfering. (6. Mr. +H. Sidgwick remarks, in an able discussion on this subject (the 'Academy,' +June 15, 1872, p. 231), "a superior bee, we may feel sure, would aspire to +a milder solution of the population question." Judging, however, from the +habits of many or most savages, man solves the problem by female +infanticide, polyandry and promiscuous intercourse; therefore it may well +be doubted whether it would be by a milder method. Miss Cobbe, in +commenting ('Darwinism in Morals,' 'Theological Review,' April 1872, pp. +188-191) on the same illustration, says, the PRINCIPLES of social duty +would be thus reversed; and by this, I presume, she means that the +fulfilment of a social duty would tend to the injury of individuals; but +she overlooks the fact, which she would doubtless admit, that the instincts +of the bee have been acquired for the good of the community. She goes so +far as to say that if the theory of ethics advocated in this chapter were +ever generally accepted, "I cannot but believe that in the hour of their +triumph would be sounded the knell of the virtue of mankind!" It is to be +hoped that the belief in the permanence of virtue on this earth is not held +by many persons on so weak a tenure.) Nevertheless, the bee, or any other +social animal, would gain in our supposed case, as it appears to me, some +feeling of right or wrong, or a conscience. For each individual would have +an inward sense of possessing certain stronger or more enduring instincts, +and others less strong or enduring; so that there would often be a struggle +as to which impulse should be followed; and satisfaction, dissatisfaction, +or even misery would be felt, as past impressions were compared during +their incessant passage through the mind. In this case an inward monitor +would tell the animal that it would have been better to have followed the +one impulse rather than the other. The one course ought to have been +followed, and the other ought not; the one would have been right and the +other wrong; but to these terms I shall recur. + + +SOCIABILITY. + +Animals of many kinds are social; we find even distinct species living +together; for example, some American monkeys; and united flocks of rooks, +jackdaws, and starlings. Man shews the same feeling in his strong love for +the dog, which the dog returns with interest. Every one must have noticed +how miserable horses, dogs, sheep, etc., are when separated from their +companions, and what strong mutual affection the two former kinds, at +least, shew on their reunion. It is curious to speculate on the feelings +of a dog, who will rest peacefully for hours in a room with his master or +any of the family, without the least notice being taken of him; but if left +for a short time by himself, barks or howls dismally. We will confine our +attention to the higher social animals; and pass over insects, although +some of these are social, and aid one another in many important ways. The +most common mutual service in the higher animals is to warn one another of +danger by means of the united senses of all. Every sportsman knows, as Dr. +Jaeger remarks (7. 'Die Darwin'sche Theorie,' s. 101.), how difficult it +is to approach animals in a herd or troop. Wild horses and cattle do not, +I believe, make any danger-signal; but the attitude of any one of them who +first discovers an enemy, warns the others. Rabbits stamp loudly on the +ground with their hind-feet as a signal: sheep and chamois do the same +with their forefeet, uttering likewise a whistle. Many birds, and some +mammals, post sentinels, which in the case of seals are said (8. Mr. R. +Brown in 'Proc. Zoolog. Soc.' 1868, p. 409.) generally to be the females. +The leader of a troop of monkeys acts as the sentinel, and utters cries +expressive both of danger and of safety. (9. Brehm, 'Thierleben,' B. i. +1864, s. 52, 79. For the case of the monkeys extracting thorns from each +other, see s. 54. With respect to the Hamadryas turning over stones, the +fact is given (s. 76), on the evidence of Alvarez, whose observations Brehm +thinks quite trustworthy. For the cases of the old male baboons attacking +the dogs, see s. 79; and with respect to the eagle, s. 56.) Social animals +perform many little services for each other: horses nibble, and cows lick +each other, on any spot which itches: monkeys search each other for +external parasites; and Brehm states that after a troop of the +Cercopithecus griseo-viridis has rushed through a thorny brake, each monkey +stretches itself on a branch, and another monkey sitting by, +"conscientiously" examines its fur, and extracts every thorn or burr. + +Animals also render more important services to one another: thus wolves +and some other beasts of prey hunt in packs, and aid one another in +attacking their victims. Pelicans fish in concert. The Hamadryas baboons +turn over stones to find insects, etc.; and when they come to a large one, +as many as can stand round, turn it over together and share the booty. +Social animals mutually defend each other. Bull bisons in N. America, when +there is danger, drive the cows and calves into the middle of the herd, +whilst they defend the outside. I shall also in a future chapter give an +account of two young wild bulls at Chillingham attacking an old one in +concert, and of two stallions together trying to drive away a third +stallion from a troop of mares. In Abyssinia, Brehm encountered a great +troop of baboons who were crossing a valley: some had already ascended the +opposite mountain, and some were still in the valley; the latter were +attacked by the dogs, but the old males immediately hurried down from the +rocks, and with mouths widely opened, roared so fearfully, that the dogs +quickly drew back. They were again encouraged to the attack; but by this +time all the baboons had reascended the heights, excepting a young one, +about six months old, who, loudly calling for aid, climbed on a block of +rock, and was surrounded. Now one of the largest males, a true hero, came +down again from the mountain, slowly went to the young one, coaxed him, and +triumphantly led him away--the dogs being too much astonished to make an +attack. I cannot resist giving another scene which was witnessed by this +same naturalist; an eagle seized a young Cercopithecus, which, by clinging +to a branch, was not at once carried off; it cried loudly for assistance, +upon which the other members of the troop, with much uproar, rushed to the +rescue, surrounded the eagle, and pulled out so many feathers, that he no +longer thought of his prey, but only how to escape. This eagle, as Brehm +remarks, assuredly would never again attack a single monkey of a troop. +(10. Mr. Belt gives the case of a spider-monkey (Ateles) in Nicaragua, +which was heard screaming for nearly two hours in the forest, and was found +with an eagle perched close by it. The bird apparently feared to attack as +long as it remained face to face; and Mr. Belt believes, from what he has +seen of the habits of these monkeys, that they protect themselves from +eagles by keeping two or three together. 'The Naturalist in Nicaragua,' +1874, p. 118.) + +It is certain that associated animals have a feeling of love for each +other, which is not felt by non-social adult animals. How far in most +cases they actually sympathise in the pains and pleasures of others, is +more doubtful, especially with respect to pleasures. Mr. Buxton, however, +who had excellent means of observation (11. 'Annals and Magazine of +Natural History,' November 1868, p. 382.), states that his macaws, which +lived free in Norfolk, took "an extravagant interest" in a pair with a +nest; and whenever the female left it, she was surrounded by a troop +"screaming horrible acclamations in her honour." It is often difficult to +judge whether animals have any feeling for the sufferings of others of +their kind. Who can say what cows feel, when they surround and stare +intently on a dying or dead companion; apparently, however, as Houzeau +remarks, they feel no pity. That animals sometimes are far from feeling +any sympathy is too certain; for they will expel a wounded animal from the +herd, or gore or worry it to death. This is almost the blackest fact in +natural history, unless, indeed, the explanation which has been suggested +is true, that their instinct or reason leads them to expel an injured +companion, lest beasts of prey, including man, should be tempted to follow +the troop. In this case their conduct is not much worse than that of the +North American Indians, who leave their feeble comrades to perish on the +plains; or the Fijians, who, when their parents get old, or fall ill, bury +them alive. (12. Sir J. Lubbock, 'Prehistoric Times,' 2nd ed., p. 446.) + +Many animals, however, certainly sympathise with each other's distress or +danger. This is the case even with birds. Captain Stansbury (13. As +quoted by Mr. L.H. Morgan, 'The American Beaver,' 1868, p. 272. Capt. +Stansbury also gives an interesting account of the manner in which a very +young pelican, carried away by a strong stream, was guided and encouraged +in its attempts to reach the shore by half a dozen old birds.) found on a +salt lake in Utah an old and completely blind pelican, which was very fat, +and must have been well fed for a long time by his companions. Mr. Blyth, +as he informs me, saw Indian crows feeding two or three of their companions +which were blind; and I have heard of an analogous case with the domestic +cock. We may, if we choose, call these actions instinctive; but such cases +are much too rare for the development of any special instinct. (14. As +Mr. Bain states, "effective aid to a sufferer springs from sympathy +proper:" 'Mental and Moral Science,' 1868, p. 245.) I have myself seen a +dog, who never passed a cat who lay sick in a basket, and was a great +friend of his, without giving her a few licks with his tongue, the surest +sign of kind feeling in a dog. + +It must be called sympathy that leads a courageous dog to fly at any one +who strikes his master, as he certainly will. I saw a person pretending to +beat a lady, who had a very timid little dog on her lap, and the trial had +never been made before; the little creature instantly jumped away, but +after the pretended beating was over, it was really pathetic to see how +perseveringly he tried to lick his mistress's face, and comfort her. Brehm +(15. 'Thierleben,' B. i. s. 85.) states that when a baboon in confinement +was pursued to be punished, the others tried to protect him. It must have +been sympathy in the cases above given which led the baboons and +Cercopitheci to defend their young comrades from the dogs and the eagle. I +will give only one other instance of sympathetic and heroic conduct, in the +case of a little American monkey. Several years ago a keeper at the +Zoological Gardens shewed me some deep and scarcely healed wounds on the +nape of his own neck, inflicted on him, whilst kneeling on the floor, by a +fierce baboon. The little American monkey, who was a warm friend of this +keeper, lived in the same large compartment, and was dreadfully afraid of +the great baboon. Nevertheless, as soon as he saw his friend in peril, he +rushed to the rescue, and by screams and bites so distracted the baboon +that the man was able to escape, after, as the surgeon thought, running +great risk of his life. + +Besides love and sympathy, animals exhibit other qualities connected with +the social instincts, which in us would be called moral; and I agree with +Agassiz (16. 'De l'Espèce et de la Classe,' 1869, p. 97.) that dogs +possess something very like a conscience. + +Dogs possess some power of self-command, and this does not appear to be +wholly the result of fear. As Braubach (17. 'Die Darwin'sche Art-Lehre,' +1869, s. 54.) remarks, they will refrain from stealing food in the absence +of their master. They have long been accepted as the very type of fidelity +and obedience. But the elephant is likewise very faithful to his driver or +keeper, and probably considers him as the leader of the herd. Dr. Hooker +informs me that an elephant, which he was riding in India, became so deeply +bogged that he remained stuck fast until the next day, when he was +extricated by men with ropes. Under such circumstances elephants will +seize with their trunks any object, dead or alive, to place under their +knees, to prevent their sinking deeper in the mud; and the driver was +dreadfully afraid lest the animal should have seized Dr. Hooker and crushed +him to death. But the driver himself, as Dr. Hooker was assured, ran no +risk. This forbearance under an emergency so dreadful for a heavy animal, +is a wonderful proof of noble fidelity. (18. See also Hooker's 'Himalayan +Journals,' vol. ii. 1854, p. 333.) + +All animals living in a body, which defend themselves or attack their +enemies in concert, must indeed be in some degree faithful to one another; +and those that follow a leader must be in some degree obedient. When the +baboons in Abyssinia (19. Brehm, 'Thierleben,' B. i. s. 76.) plunder a +garden, they silently follow their leader; and if an imprudent young animal +makes a noise, he receives a slap from the others to teach him silence and +obedience. Mr. Galton, who has had excellent opportunities for observing +the half-wild cattle in S. Africa, says (20. See his extremely interesting +paper on 'Gregariousness in Cattle, and in Man,' 'Macmillan's Magazine,' +Feb. 1871, p. 353.), that they cannot endure even a momentary separation +from the herd. They are essentially slavish, and accept the common +determination, seeking no better lot than to be led by any one ox who has +enough self-reliance to accept the position. The men who break in these +animals for harness, watch assiduously for those who, by grazing apart, +shew a self-reliant disposition, and these they train as fore-oxen. Mr. +Galton adds that such animals are rare and valuable; and if many were born +they would soon be eliminated, as lions are always on the look-out for the +individuals which wander from the herd. + +With respect to the impulse which leads certain animals to associate +together, and to aid one another in many ways, we may infer that in most +cases they are impelled by the same sense of satisfaction or pleasure which +they experience in performing other instinctive actions; or by the same +sense of dissatisfaction as when other instinctive actions are checked. We +see this in innumerable instances, and it is illustrated in a striking +manner by the acquired instincts of our domesticated animals; thus a young +shepherd-dog delights in driving and running round a flock of sheep, but +not in worrying them; a young fox-hound delights in hunting a fox, whilst +some other kinds of dogs, as I have witnessed, utterly disregard foxes. +What a strong feeling of inward satisfaction must impel a bird, so full of +activity, to brood day after day over her eggs. Migratory birds are quite +miserable if stopped from migrating; perhaps they enjoy starting on their +long flight; but it is hard to believe that the poor pinioned goose, +described by Audubon, which started on foot at the proper time for its +journey of probably more than a thousand miles, could have felt any joy in +doing so. Some instincts are determined solely by painful feelings, as by +fear, which leads to self-preservation, and is in some cases directed +towards special enemies. No one, I presume, can analyse the sensations of +pleasure or pain. In many instances, however, it is probable that +instincts are persistently followed from the mere force of inheritance, +without the stimulus of either pleasure or pain. A young pointer, when it +first scents game, apparently cannot help pointing. A squirrel in a cage +who pats the nuts which it cannot eat, as if to bury them in the ground, +can hardly be thought to act thus, either from pleasure or pain. Hence the +common assumption that men must be impelled to every action by experiencing +some pleasure or pain may be erroneous. Although a habit may be blindly +and implicitly followed, independently of any pleasure or pain felt at the +moment, yet if it be forcibly and abruptly checked, a vague sense of +dissatisfaction is generally experienced. + +It has often been assumed that animals were in the first place rendered +social, and that they feel as a consequence uncomfortable when separated +from each other, and comfortable whilst together; but it is a more probable +view that these sensations were first developed, in order that those +animals which would profit by living in society, should be induced to live +together, in the same manner as the sense of hunger and the pleasure of +eating were, no doubt, first acquired in order to induce animals to eat. +The feeling of pleasure from society is probably an extension of the +parental or filial affections, since the social instinct seems to be +developed by the young remaining for a long time with their parents; and +this extension may be attributed in part to habit, but chiefly to natural +selection. With those animals which were benefited by living in close +association, the individuals which took the greatest pleasure in society +would best escape various dangers, whilst those that cared least for their +comrades, and lived solitary, would perish in greater numbers. With +respect to the origin of the parental and filial affections, which +apparently lie at the base of the social instincts, we know not the steps +by which they have been gained; but we may infer that it has been to a +large extent through natural selection. So it has almost certainly been +with the unusual and opposite feeling of hatred between the nearest +relations, as with the worker-bees which kill their brother drones, and +with the queen-bees which kill their daughter-queens; the desire to destroy +their nearest relations having been in this case of service to the +community. Parental affection, or some feeling which replaces it, has been +developed in certain animals extremely low in the scale, for example, in +star-fishes and spiders. It is also occasionally present in a few members +alone in a whole group of animals, as in the genus Forficula, or earwigs. + +The all-important emotion of sympathy is distinct from that of love. A +mother may passionately love her sleeping and passive infant, but she can +hardly at such times be said to feel sympathy for it. The love of a man +for his dog is distinct from sympathy, and so is that of a dog for his +master. Adam Smith formerly argued, as has Mr. Bain recently, that the +basis of sympathy lies in our strong retentiveness of former states of pain +or pleasure. Hence, "the sight of another person enduring hunger, cold, +fatigue, revives in us some recollection of these states, which are painful +even in idea." We are thus impelled to relieve the sufferings of another, +in order that our own painful feelings may be at the same time relieved. +In like manner we are led to participate in the pleasures of others. (21. +See the first and striking chapter in Adam Smith's 'Theory of Moral +Sentiments.' Also 'Mr. Bain's Mental and Moral Science,' 1868, pp. 244, +and 275-282. Mr. Bain states, that, "sympathy is, indirectly, a source of +pleasure to the sympathiser"; and he accounts for this through reciprocity. +He remarks that "the person benefited, or others in his stead, may make up, +by sympathy and good offices returned, for all the sacrifice." But if, as +appears to be the case, sympathy is strictly an instinct, its exercise +would give direct pleasure, in the same manner as the exercise, as before +remarked, of almost every other instinct.) But I cannot see how this view +explains the fact that sympathy is excited, in an immeasurably stronger +degree, by a beloved, than by an indifferent person. The mere sight of +suffering, independently of love, would suffice to call up in us vivid +recollections and associations. The explanation may lie in the fact that, +with all animals, sympathy is directed solely towards the members of the +same community, and therefore towards known, and more or less beloved +members, but not to all the individuals of the same species. This fact is +not more surprising than that the fears of many animals should be directed +against special enemies. Species which are not social, such as lions and +tigers, no doubt feel sympathy for the suffering of their own young, but +not for that of any other animal. With mankind, selfishness, experience, +and imitation, probably add, as Mr. Bain has shewn, to the power of +sympathy; for we are led by the hope of receiving good in return to perform +acts of sympathetic kindness to others; and sympathy is much strengthened +by habit. In however complex a manner this feeling may have originated, as +it is one of high importance to all those animals which aid and defend one +another, it will have been increased through natural selection; for those +communities, which included the greatest number of the most sympathetic +members, would flourish best, and rear the greatest number of offspring. + +It is, however, impossible to decide in many cases whether certain social +instincts have been acquired through natural selection, or are the indirect +result of other instincts and faculties, such as sympathy, reason, +experience, and a tendency to imitation; or again, whether they are simply +the result of long-continued habit. So remarkable an instinct as the +placing sentinels to warn the community of danger, can hardly have been the +indirect result of any of these faculties; it must, therefore, have been +directly acquired. On the other hand, the habit followed by the males of +some social animals of defending the community, and of attacking their +enemies or their prey in concert, may perhaps have originated from mutual +sympathy; but courage, and in most cases strength, must have been +previously acquired, probably through natural selection. + +Of the various instincts and habits, some are much stronger than others; +that is, some either give more pleasure in their performance, and more +distress in their prevention, than others; or, which is probably quite as +important, they are, through inheritance, more persistently followed, +without exciting any special feeling of pleasure or pain. We are ourselves +conscious that some habits are much more difficult to cure or change than +others. Hence a struggle may often be observed in animals between +different instincts, or between an instinct and some habitual disposition; +as when a dog rushes after a hare, is rebuked, pauses, hesitates, pursues +again, or returns ashamed to his master; or as between the love of a female +dog for her young puppies and for her master,--for she may be seen to slink +away to them, as if half ashamed of not accompanying her master. But the +most curious instance known to me of one instinct getting the better of +another, is the migratory instinct conquering the maternal instinct. The +former is wonderfully strong; a confined bird will at the proper season +beat her breast against the wires of her cage, until it is bare and bloody. +It causes young salmon to leap out of the fresh water, in which they could +continue to exist, and thus unintentionally to commit suicide. Every one +knows how strong the maternal instinct is, leading even timid birds to face +great danger, though with hesitation, and in opposition to the instinct of +self-preservation. Nevertheless, the migratory instinct is so powerful, +that late in the autumn swallows, house-martins, and swifts frequently +desert their tender young, leaving them to perish miserably in their nests. +(22. This fact, the Rev. L. Jenyns states (see his edition of 'White's +Nat. Hist. of Selborne,' 1853, p. 204) was first recorded by the +illustrious Jenner, in 'Phil. Transact.' 1824, and has since been confirmed +by several observers, especially by Mr. Blackwall. This latter careful +observer examined, late in the autumn, during two years, thirty-six nests; +he found that twelve contained young dead birds, five contained eggs on the +point of being hatched, and three, eggs not nearly hatched. Many birds, +not yet old enough for a prolonged flight, are likewise deserted and left +behind. See Blackwall, 'Researches in Zoology,' 1834, pp. 108, 118. For +some additional evidence, although this is not wanted, see Leroy, 'Lettres +Phil.' 1802, p. 217. For Swifts, Gould's 'Introduction to the Birds of +Great Britain,' 1823, p. 5. Similar cases have been observed in Canada by +Mr. Adams; 'Pop. Science Review,' July 1873, p. 283.) + +We can perceive that an instinctive impulse, if it be in any way more +beneficial to a species than some other or opposed instinct, would be +rendered the more potent of the two through natural selection; for the +individuals which had it most strongly developed would survive in larger +numbers. Whether this is the case with the migratory in comparison with +the maternal instinct, may be doubted. The great persistence, or steady +action of the former at certain seasons of the year during the whole day, +may give it for a time paramount force. + +MAN A SOCIAL ANIMAL. + +Every one will admit that man is a social being. We see this in his +dislike of solitude, and in his wish for society beyond that of his own +family. Solitary confinement is one of the severest punishments which can +be inflicted. Some authors suppose that man primevally lived in single +families; but at the present day, though single families, or only two or +three together, roam the solitudes of some savage lands, they always, as +far as I can discover, hold friendly relations with other families +inhabiting the same district. Such families occasionally meet in council, +and unite for their common defence. It is no argument against savage man +being a social animal, that the tribes inhabiting adjacent districts are +almost always at war with each other; for the social instincts never extend +to all the individuals of the same species. Judging from the analogy of +the majority of the Quadrumana, it is probable that the early ape-like +progenitors of man were likewise social; but this is not of much importance +for us. Although man, as he now exists, has few special instincts, having +lost any which his early progenitors may have possessed, this is no reason +why he should not have retained from an extremely remote period some degree +of instinctive love and sympathy for his fellows. We are indeed all +conscious that we do possess such sympathetic feelings (23. Hume remarks +('An Enquiry Concerning the Principles of Morals,' edit. of 1751, p. 132), +"There seems a necessity for confessing that the happiness and misery of +others are not spectacles altogether indifferent to us, but that the view +of the former...communicates a secret joy; the appearance of the latter... +throws a melancholy damp over the imagination."); but our consciousness +does not tell us whether they are instinctive, having originated long ago +in the same manner as with the lower animals, or whether they have been +acquired by each of us during our early years. As man is a social animal, +it is almost certain that he would inherit a tendency to be faithful to his +comrades, and obedient to the leader of his tribe; for these qualities are +common to most social animals. He would consequently possess some capacity +for self-command. He would from an inherited tendency be willing to +defend, in concert with others, his fellow-men; and would be ready to aid +them in any way, which did not too greatly interfere with his own welfare +or his own strong desires. + +The social animals which stand at the bottom of the scale are guided almost +exclusively, and those which stand higher in the scale are largely guided, +by special instincts in the aid which they give to the members of the same +community; but they are likewise in part impelled by mutual love and +sympathy, assisted apparently by some amount of reason. Although man, as +just remarked, has no special instincts to tell him how to aid his fellow- +men, he still has the impulse, and with his improved intellectual faculties +would naturally be much guided in this respect by reason and experience. +Instinctive sympathy would also cause him to value highly the approbation +of his fellows; for, as Mr. Bain has clearly shewn (24. 'Mental and Moral +Science,' 1868, p. 254.), the love of praise and the strong feeling of +glory, and the still stronger horror of scorn and infamy, "are due to the +workings of sympathy." Consequently man would be influenced in the highest +degree by the wishes, approbation, and blame of his fellow-men, as +expressed by their gestures and language. Thus the social instincts, which +must have been acquired by man in a very rude state, and probably even by +his early ape-like progenitors, still give the impulse to some of his best +actions; but his actions are in a higher degree determined by the expressed +wishes and judgment of his fellow-men, and unfortunately very often by his +own strong selfish desires. But as love, sympathy and self-command become +strengthened by habit, and as the power of reasoning becomes clearer, so +that man can value justly the judgments of his fellows, he will feel +himself impelled, apart from any transitory pleasure or pain, to certain +lines of conduct. He might then declare--not that any barbarian or +uncultivated man could thus think--I am the supreme judge of my own +conduct, and in the words of Kant, I will not in my own person violate the +dignity of humanity. + +THE MORE ENDURING SOCIAL INSTINCTS CONQUER THE LESS PERSISTENT INSTINCTS. + +We have not, however, as yet considered the main point, on which, from our +present point of view, the whole question of the moral sense turns. Why +should a man feel that he ought to obey one instinctive desire rather than +another? Why is he bitterly regretful, if he has yielded to a strong sense +of self-preservation, and has not risked his life to save that of a fellow- +creature? or why does he regret having stolen food from hunger? + +It is evident in the first place, that with mankind the instinctive +impulses have different degrees of strength; a savage will risk his own +life to save that of a member of the same community, but will be wholly +indifferent about a stranger: a young and timid mother urged by the +maternal instinct will, without a moment's hesitation, run the greatest +danger for her own infant, but not for a mere fellow-creature. +Nevertheless many a civilised man, or even boy, who never before risked his +life for another, but full of courage and sympathy, has disregarded the +instinct of self-preservation, and plunged at once into a torrent to save a +drowning man, though a stranger. In this case man is impelled by the same +instinctive motive, which made the heroic little American monkey, formerly +described, save his keeper, by attacking the great and dreaded baboon. +Such actions as the above appear to be the simple result of the greater +strength of the social or maternal instincts rather than that of any other +instinct or motive; for they are performed too instantaneously for +reflection, or for pleasure or pain to be felt at the time; though, if +prevented by any cause, distress or even misery might be felt. In a timid +man, on the other hand, the instinct of self-preservation might be so +strong, that he would be unable to force himself to run any such risk, +perhaps not even for his own child. + +I am aware that some persons maintain that actions performed impulsively, +as in the above cases, do not come under the dominion of the moral sense, +and cannot be called moral. They confine this term to actions done +deliberately, after a victory over opposing desires, or when prompted by +some exalted motive. But it appears scarcely possible to draw any clear +line of distinction of this kind. (25. I refer here to the distinction +between what has been called MATERIAL and FORMAL morality. I am glad to +find that Professor Huxley ('Critiques and Addresses,' 1873, p. 287) takes +the same view on this subject as I do. Mr. Leslie Stephen remarks ('Essays +on Freethinking and Plain Speaking,' 1873, p. 83), "the metaphysical +distinction, between material and formal morality is as irrelevant as other +such distinctions.") As far as exalted motives are concerned, many +instances have been recorded of savages, destitute of any feeling of +general benevolence towards mankind, and not guided by any religious +motive, who have deliberately sacrificed their lives as prisoners(26. I +have given one such case, namely of three Patagonian Indians who preferred +being shot, one after the other, to betraying the plans of their companions +in war ('Journal of Researches,' 1845, p. 103).), rather than betray their +comrades; and surely their conduct ought to be considered as moral. As far +as deliberation, and the victory over opposing motives are concerned, +animals may be seen doubting between opposed instincts, in rescuing their +offspring or comrades from danger; yet their actions, though done for the +good of others, are not called moral. Moreover, anything performed very +often by us, will at last be done without deliberation or hesitation, and +can then hardly be distinguished from an instinct; yet surely no one will +pretend that such an action ceases to be moral. On the contrary, we all +feel that an act cannot be considered as perfect, or as performed in the +most noble manner, unless it be done impulsively, without deliberation or +effort, in the same manner as by a man in whom the requisite qualities are +innate. He who is forced to overcome his fear or want of sympathy before +he acts, deserves, however, in one way higher credit than the man whose +innate disposition leads him to a good act without effort. As we cannot +distinguish between motives, we rank all actions of a certain class as +moral, if performed by a moral being. A moral being is one who is capable +of comparing his past and future actions or motives, and of approving or +disapproving of them. We have no reason to suppose that any of the lower +animals have this capacity; therefore, when a Newfoundland dog drags a +child out of the water, or a monkey faces danger to rescue its comrade, or +takes charge of an orphan monkey, we do not call its conduct moral. But in +the case of man, who alone can with certainty be ranked as a moral being, +actions of a certain class are called moral, whether performed +deliberately, after a struggle with opposing motives, or impulsively +through instinct, or from the effects of slowly-gained habit. + +But to return to our more immediate subject. Although some instincts are +more powerful than others, and thus lead to corresponding actions, yet it +is untenable, that in man the social instincts (including the love of +praise and fear of blame) possess greater strength, or have, through long +habit, acquired greater strength than the instincts of self-preservation, +hunger, lust, vengeance, etc. Why then does man regret, even though trying +to banish such regret, that he has followed the one natural impulse rather +than the other; and why does he further feel that he ought to regret his +conduct? Man in this respect differs profoundly from the lower animals. +Nevertheless we can, I think, see with some degree of clearness the reason +of this difference. + +Man, from the activity of his mental faculties, cannot avoid reflection: +past impressions and images are incessantly and clearly passing through his +mind. Now with those animals which live permanently in a body, the social +instincts are ever present and persistent. Such animals are always ready +to utter the danger-signal, to defend the community, and to give aid to +their fellows in accordance with their habits; they feel at all times, +without the stimulus of any special passion or desire, some degree of love +and sympathy for them; they are unhappy if long separated from them, and +always happy to be again in their company. So it is with ourselves. Even +when we are quite alone, how often do we think with pleasure or pain of +what others think of us,--of their imagined approbation or disapprobation; +and this all follows from sympathy, a fundamental element of the social +instincts. A man who possessed no trace of such instincts would be an +unnatural monster. On the other hand, the desire to satisfy hunger, or any +passion such as vengeance, is in its nature temporary, and can for a time +be fully satisfied. Nor is it easy, perhaps hardly possible, to call up +with complete vividness the feeling, for instance, of hunger; nor indeed, +as has often been remarked, of any suffering. The instinct of self- +preservation is not felt except in the presence of danger; and many a +coward has thought himself brave until he has met his enemy face to face. +The wish for another man's property is perhaps as persistent a desire as +any that can be named; but even in this case the satisfaction of actual +possession is generally a weaker feeling than the desire: many a thief, if +not a habitual one, after success has wondered why he stole some article. +(27. Enmity or hatred seems also to be a highly persistent feeling, perhaps +more so than any other that can be named. Envy is defined as hatred of +another for some excellence or success; and Bacon insists (Essay ix.), "Of +all other affections envy is the most importune and continual." Dogs are +very apt to hate both strange men and strange dogs, especially if they live +near at hand, but do not belong to the same family, tribe, or clan; this +feeling would thus seem to be innate, and is certainly a most persistent +one. It seems to be the complement and converse of the true social +instinct. From what we hear of savages, it would appear that something of +the same kind holds good with them. If this be so, it would be a small +step in any one to transfer such feelings to any member of the same tribe +if he had done him an injury and had become his enemy. Nor is it probable +that the primitive conscience would reproach a man for injuring his enemy; +rather it would reproach him, if he had not revenged himself. To do good +in return for evil, to love your enemy, is a height of morality to which it +may be doubted whether the social instincts would, by themselves, have ever +led us. It is necessary that these instincts, together with sympathy, +should have been highly cultivated and extended by the aid of reason, +instruction, and the love or fear of God, before any such golden rule would +ever be thought of and obeyed.) + +A man cannot prevent past impressions often repassing through his mind; he +will thus be driven to make a comparison between the impressions of past +hunger, vengeance satisfied, or danger shunned at other men's cost, with +the almost ever-present instinct of sympathy, and with his early knowledge +of what others consider as praiseworthy or blameable. This knowledge +cannot be banished from his mind, and from instinctive sympathy is esteemed +of great moment. He will then feel as if he had been baulked in following +a present instinct or habit, and this with all animals causes +dissatisfaction, or even misery. + +The above case of the swallow affords an illustration, though of a reversed +nature, of a temporary though for the time strongly persistent instinct +conquering another instinct, which is usually dominant over all others. At +the proper season these birds seem all day long to be impressed with the +desire to migrate; their habits change; they become restless, are noisy and +congregate in flocks. Whilst the mother-bird is feeding, or brooding over +her nestlings, the maternal instinct is probably stronger than the +migratory; but the instinct which is the more persistent gains the victory, +and at last, at a moment when her young ones are not in sight, she takes +flight and deserts them. When arrived at the end of her long journey, and +the migratory instinct has ceased to act, what an agony of remorse the bird +would feel, if, from being endowed with great mental activity, she could +not prevent the image constantly passing through her mind, of her young +ones perishing in the bleak north from cold and hunger. + +At the moment of action, man will no doubt be apt to follow the stronger +impulse; and though this may occasionally prompt him to the noblest deeds, +it will more commonly lead him to gratify his own desires at the expense of +other men. But after their gratification when past and weaker impressions +are judged by the ever-enduring social instinct, and by his deep regard for +the good opinion of his fellows, retribution will surely come. He will +then feel remorse, repentance, regret, or shame; this latter feeling, +however, relates almost exclusively to the judgment of others. He will +consequently resolve more or less firmly to act differently for the future; +and this is conscience; for conscience looks backwards, and serves as a +guide for the future. + +The nature and strength of the feelings which we call regret, shame, +repentance or remorse, depend apparently not only on the strength of the +violated instinct, but partly on the strength of the temptation, and often +still more on the judgment of our fellows. How far each man values the +appreciation of others, depends on the strength of his innate or acquired +feeling of sympathy; and on his own capacity for reasoning out the remote +consequences of his acts. Another element is most important, although not +necessary, the reverence or fear of the Gods, or Spirits believed in by +each man: and this applies especially in cases of remorse. Several +critics have objected that though some slight regret or repentance may be +explained by the view advocated in this chapter, it is impossible thus to +account for the soul-shaking feeling of remorse. But I can see little +force in this objection. My critics do not define what they mean by +remorse, and I can find no definition implying more than an overwhelming +sense of repentance. Remorse seems to bear the same relation to +repentance, as rage does to anger, or agony to pain. It is far from +strange that an instinct so strong and so generally admired, as maternal +love, should, if disobeyed, lead to the deepest misery, as soon as the +impression of the past cause of disobedience is weakened. Even when an +action is opposed to no special instinct, merely to know that our friends +and equals despise us for it is enough to cause great misery. Who can +doubt that the refusal to fight a duel through fear has caused many men an +agony of shame? Many a Hindoo, it is said, has been stirred to the bottom +of his soul by having partaken of unclean food. Here is another case of +what must, I think, be called remorse. Dr. Landor acted as a magistrate in +West Australia, and relates (28. 'Insanity in Relation to Law,' Ontario, +United States, 1871, p. 1.), that a native on his farm, after losing one of +his wives from disease, came and said that, "he was going to a distant +tribe to spear a woman, to satisfy his sense of duty to his wife. I told +him that if he did so, I would send him to prison for life. He remained +about the farm for some months, but got exceedingly thin, and complained +that he could not rest or eat, that his wife's spirit was haunting him, +because he had not taken a life for hers. I was inexorable, and assured +him that nothing should save him if he did." Nevertheless the man +disappeared for more than a year, and then returned in high condition; and +his other wife told Dr. Landor that her husband had taken the life of a +woman belonging to a distant tribe; but it was impossible to obtain legal +evidence of the act. The breach of a rule held sacred by the tribe, will +thus, as it seems, give rise to the deepest feelings,--and this quite apart +from the social instincts, excepting in so far as the rule is grounded on +the judgment of the community. How so many strange superstitions have +arisen throughout the world we know not; nor can we tell how some real and +great crimes, such as incest, have come to be held in an abhorrence (which +is not however quite universal) by the lowest savages. It is even doubtful +whether in some tribes incest would be looked on with greater horror, than +would the marriage of a man with a woman bearing the same name, though not +a relation. "To violate this law is a crime which the Australians hold in +the greatest abhorrence, in this agreeing exactly with certain tribes of +North America. When the question is put in either district, is it worse to +kill a girl of a foreign tribe, or to marry a girl of one's own, an answer +just opposite to ours would be given without hesitation." (29. E.B. +Tylor, in 'Contemporary Review,' April 1873, p. 707.) We may, therefore, +reject the belief, lately insisted on by some writers, that the abhorrence +of incest is due to our possessing a special God-implanted conscience. On +the whole it is intelligible, that a man urged by so powerful a sentiment +as remorse, though arising as above explained, should be led to act in a +manner, which he has been taught to believe serves as an expiation, such as +delivering himself up to justice. + +Man prompted by his conscience, will through long habit acquire such +perfect self-command, that his desires and passions will at last yield +instantly and without a struggle to his social sympathies and instincts, +including his feeling for the judgment of his fellows. The still hungry, +or the still revengeful man will not think of stealing food, or of wreaking +his vengeance. It is possible, or as we shall hereafter see, even +probable, that the habit of self-command may, like other habits, be +inherited. Thus at last man comes to feel, through acquired and perhaps +inherited habit, that it is best for him to obey his more persistent +impulses. The imperious word "ought" seems merely to imply the +consciousness of the existence of a rule of conduct, however it may have +originated. Formerly it must have been often vehemently urged that an +insulted gentleman OUGHT to fight a duel. We even say that a pointer OUGHT +to point, and a retriever to retrieve game. If they fail to do so, they +fail in their duty and act wrongly. + +If any desire or instinct leading to an action opposed to the good of +others still appears, when recalled to mind, as strong as, or stronger +than, the social instinct, a man will feel no keen regret at having +followed it; but he will be conscious that if his conduct were known to his +fellows, it would meet with their disapprobation; and few are so destitute +of sympathy as not to feel discomfort when this is realised. If he has no +such sympathy, and if his desires leading to bad actions are at the time +strong, and when recalled are not over-mastered by the persistent social +instincts, and the judgment of others, then he is essentially a bad man +(30. Dr. Prosper Despine, in his Psychologie Naturelle, 1868 (tom. i. p. +243; tom. ii. p. 169) gives many curious cases of the worst criminals, who +apparently have been entirely destitute of conscience.); and the sole +restraining motive left is the fear of punishment, and the conviction that +in the long run it would be best for his own selfish interests to regard +the good of others rather than his own. + +It is obvious that every one may with an easy conscience gratify his own +desires, if they do not interfere with his social instincts, that is with +the good of others; but in order to be quite free from self-reproach, or at +least of anxiety, it is almost necessary for him to avoid the +disapprobation, whether reasonable or not, of his fellow-men. Nor must he +break through the fixed habits of his life, especially if these are +supported by reason; for if he does, he will assuredly feel +dissatisfaction. He must likewise avoid the reprobation of the one God or +gods in whom, according to his knowledge or superstition, he may believe; +but in this case the additional fear of divine punishment often supervenes. + +THE STRICTLY SOCIAL VIRTUES AT FIRST ALONE REGARDED. + +The above view of the origin and nature of the moral sense, which tells us +what we ought to do, and of the conscience which reproves us if we disobey +it, accords well with what we see of the early and undeveloped condition of +this faculty in mankind. The virtues which must be practised, at least +generally, by rude men, so that they may associate in a body, are those +which are still recognised as the most important. But they are practised +almost exclusively in relation to the men of the same tribe; and their +opposites are not regarded as crimes in relation to the men of other +tribes. No tribe could hold together if murder, robbery, treachery, etc., +were common; consequently such crimes within the limits of the same tribe +"are branded with everlasting infamy" (31. See an able article in the +'North British Review,' 1867, p. 395. See also Mr. W. Bagehot's articles +on the Importance of Obedience and Coherence to Primitive Man, in the +'Fortnightly Review,' 1867, p. 529, and 1868, p. 457, etc.); but excite no +such sentiment beyond these limits. A North-American Indian is well +pleased with himself, and is honoured by others, when he scalps a man of +another tribe; and a Dyak cuts off the head of an unoffending person, and +dries it as a trophy. The murder of infants has prevailed on the largest +scale throughout the world (32. The fullest account which I have met with +is by Dr. Gerland, in his 'Ueber den Aussterben der Naturvölker,' 1868; but +I shall have to recur to the subject of infanticide in a future chapter.), +and has met with no reproach; but infanticide, especially of females, has +been thought to be good for the tribe, or at least not injurious. Suicide +during former times was not generally considered as a crime (33. See the +very interesting discussion on suicide in Lecky's 'History of European +Morals,' vol. i. 1869, p. 223. With respect to savages, Mr. Winwood Reade +informs me that the negroes of West Africa often commit suicide. It is +well known how common it was amongst the miserable aborigines of South +America after the Spanish conquest. For New Zealand, see the voyage of the +Novara, and for the Aleutian Islands, Müller, as quoted by Houzeau, 'Les +Facultés Mentales,' etc., tom. ii. p. 136.), but rather, from the courage +displayed, as an honourable act; and it is still practised by some semi- +civilised and savage nations without reproach, for it does not obviously +concern others of the tribe. It has been recorded that an Indian Thug +conscientiously regretted that he had not robbed and strangled as many +travellers as did his father before him. In a rude state of civilisation +the robbery of strangers is, indeed, generally considered as honourable. + + +Slavery, although in some ways beneficial during ancient times (34. See +Mr. Bagehot, 'Physics and Politics,' 1872, p. 72.), is a great crime; yet +it was not so regarded until quite recently, even by the most civilised +nations. And this was especially the case, because the slaves belonged in +general to a race different from that of their masters. As barbarians do +not regard the opinion of their women, wives are commonly treated like +slaves. Most savages are utterly indifferent to the sufferings of +strangers, or even delight in witnessing them. It is well known that the +women and children of the North-American Indians aided in torturing their +enemies. Some savages take a horrid pleasure in cruelty to animals (35. +See, for instance, Mr. Hamilton's account of the Kaffirs, 'Anthropological +Review,' 1870, p. xv.), and humanity is an unknown virtue. Nevertheless, +besides the family affections, kindness is common, especially during +sickness, between the members of the same tribe, and is sometimes extended +beyond these limits. Mungo Park's touching account of the kindness of the +negro women of the interior to him is well known. Many instances could be +given of the noble fidelity of savages towards each other, but not to +strangers; common experience justifies the maxim of the Spaniard, "Never, +never trust an Indian." There cannot be fidelity without truth; and this +fundamental virtue is not rare between the members of the same tribe: thus +Mungo Park heard the negro women teaching their young children to love the +truth. This, again, is one of the virtues which becomes so deeply rooted +in the mind, that it is sometimes practised by savages, even at a high +cost, towards strangers; but to lie to your enemy has rarely been thought a +sin, as the history of modern diplomacy too plainly shews. As soon as a +tribe has a recognised leader, disobedience becomes a crime, and even +abject submission is looked at as a sacred virtue. + +As during rude times no man can be useful or faithful to his tribe without +courage, this quality has universally been placed in the highest rank; and +although in civilised countries a good yet timid man may be far more useful +to the community than a brave one, we cannot help instinctively honouring +the latter above a coward, however benevolent. Prudence, on the other +hand, which does not concern the welfare of others, though a very useful +virtue, has never been highly esteemed. As no man can practise the virtues +necessary for the welfare of his tribe without self-sacrifice, self- +command, and the power of endurance, these qualities have been at all times +highly and most justly valued. The American savage voluntarily submits to +the most horrid tortures without a groan, to prove and strengthen his +fortitude and courage; and we cannot help admiring him, or even an Indian +Fakir, who, from a foolish religious motive, swings suspended by a hook +buried in his flesh. + +The other so-called self-regarding virtues, which do not obviously, though +they may really, affect the welfare of the tribe, have never been esteemed +by savages, though now highly appreciated by civilised nations. The +greatest intemperance is no reproach with savages. Utter licentiousness, +and unnatural crimes, prevail to an astounding extent. (36. Mr. M'Lennan +has given ('Primitive Marriage,' 1865, p. 176) a good collection of facts +on this head.) As soon, however, as marriage, whether polygamous, or +monogamous, becomes common, jealousy will lead to the inculcation of female +virtue; and this, being honoured, will tend to spread to the unmarried +females. How slowly it spreads to the male sex, we see at the present day. +Chastity eminently requires self-command; therefore it has been honoured +from a very early period in the moral history of civilised man. As a +consequence of this, the senseless practice of celibacy has been ranked +from a remote period as a virtue. (38. Lecky, 'History of European +Morals,' vol. i. 1869, p. 109.) The hatred of indecency, which appears to +us so natural as to be thought innate, and which is so valuable an aid to +chastity, is a modern virtue, appertaining exclusively, as Sir G. Staunton +remarks (38. 'Embassy to China,' vol. ii. p. 348.), to civilised life. +This is shewn by the ancient religious rites of various nations, by the +drawings on the walls of Pompeii, and by the practices of many savages. + +We have now seen that actions are regarded by savages, and were probably so +regarded by primeval man, as good or bad, solely as they obviously affect +the welfare of the tribe,--not that of the species, nor that of an +individual member of the tribe. This conclusion agrees well with the +belief that the so-called moral sense is aboriginally derived from the +social instincts, for both relate at first exclusively to the community. + +The chief causes of the low morality of savages, as judged by our standard, +are, firstly, the confinement of sympathy to the same tribe. Secondly, +powers of reasoning insufficient to recognise the bearing of many virtues, +especially of the self-regarding virtues, on the general welfare of the +tribe. Savages, for instance, fail to trace the multiplied evils +consequent on a want of temperance, chastity, etc. And, thirdly, weak +power of self-command; for this power has not been strengthened through +long-continued, perhaps inherited, habit, instruction and religion. + +I have entered into the above details on the immorality of savages (39. +See on this subject copious evidence in Chap. vii. of Sir J. Lubbock, +'Origin of Civilisation,' 1870.), because some authors have recently taken +a high view of their moral nature, or have attributed most of their crimes +to mistaken benevolence. (40. For instance Lecky, 'History of European +Morals,' vol. i. p. 124.) These authors appear to rest their conclusion on +savages possessing those virtues which are serviceable, or even necessary, +for the existence of the family and of the tribe,--qualities which they +undoubtedly do possess, and often in a high degree. + +CONCLUDING REMARKS. + +It was assumed formerly by philosophers of the derivative (41. This term +is used in an able article in the 'Westminster Review,' Oct. 1869, p. 498. +For the "Greatest happiness principle," see J.S. Mill, 'Utilitarianism,' p. +17.) school of morals that the foundation of morality lay in a form of +Selfishness; but more recently the "Greatest happiness principle" has been +brought prominently forward. It is, however, more correct to speak of the +latter principle as the standard, and not as the motive of conduct. +Nevertheless, all the authors whose works I have consulted, with a few +exceptions (42. Mill recognises ('System of Logic,' vol. ii. p. 422) in +the clearest manner, that actions may be performed through habit without +the anticipation of pleasure. Mr. H. Sidgwick also, in his Essay on +Pleasure and Desire ('The Contemporary Review,' April 1872, p. 671), +remarks: "To sum up, in contravention of the doctrine that our conscious +active impulses are always directed towards the production of agreeable +sensations in ourselves, I would maintain that we find everywhere in +consciousness extra-regarding impulse, directed towards something that is +not pleasure; that in many cases the impulse is so far incompatible with +the self-regarding that the two do not easily co-exist in the same moment +of consciousness." A dim feeling that our impulses do not by any means +always arise from any contemporaneous or anticipated pleasure, has, I +cannot but think, been one chief cause of the acceptance of the intuitive +theory of morality, and of the rejection of the utilitarian or "Greatest +happiness" theory. With respect to the latter theory the standard and the +motive of conduct have no doubt often been confused, but they are really in +some degree blended.), write as if there must be a distinct motive for +every action, and that this must be associated with some pleasure or +displeasure. But man seems often to act impulsively, that is from instinct +or long habit, without any consciousness of pleasure, in the same manner as +does probably a bee or ant, when it blindly follows its instincts. Under +circumstances of extreme peril, as during a fire, when a man endeavours to +save a fellow-creature without a moment's hesitation, he can hardly feel +pleasure; and still less has he time to reflect on the dissatisfaction +which he might subsequently experience if he did not make the attempt. +Should he afterwards reflect over his own conduct, he would feel that there +lies within him an impulsive power widely different from a search after +pleasure or happiness; and this seems to be the deeply planted social +instinct. + +In the case of the lower animals it seems much more appropriate to speak of +their social instincts, as having been developed for the general good +rather than for the general happiness of the species. The term, general +good, may be defined as the rearing of the greatest number of individuals +in full vigour and health, with all their faculties perfect, under the +conditions to which they are subjected. As the social instincts both of +man and the lower animals have no doubt been developed by nearly the same +steps, it would be advisable, if found practicable, to use the same +definition in both cases, and to take as the standard of morality, the +general good or welfare of the community, rather than the general +happiness; but this definition would perhaps require some limitation on +account of political ethics. + +When a man risks his life to save that of a fellow-creature, it seems also +more correct to say that he acts for the general good, rather than for the +general happiness of mankind. No doubt the welfare and the happiness of +the individual usually coincide; and a contented, happy tribe will flourish +better than one that is discontented and unhappy. We have seen that even +at an early period in the history of man, the expressed wishes of the +community will have naturally influenced to a large extent the conduct of +each member; and as all wish for happiness, the "greatest happiness +principle" will have become a most important secondary guide and object; +the social instinct, however, together with sympathy (which leads to our +regarding the approbation and disapprobation of others), having served as +the primary impulse and guide. Thus the reproach is removed of laying the +foundation of the noblest part of our nature in the base principle of +selfishness; unless, indeed, the satisfaction which every animal feels, +when it follows its proper instincts, and the dissatisfaction felt when +prevented, be called selfish. + +The wishes and opinions of the members of the same community, expressed at +first orally, but later by writing also, either form the sole guides of our +conduct, or greatly reinforce the social instincts; such opinions, however, +have sometimes a tendency directly opposed to these instincts. This latter +fact is well exemplified by the LAW OF HONOUR, that is, the law of the +opinion of our equals, and not of all our countrymen. The breach of this +law, even when the breach is known to be strictly accordant with true +morality, has caused many a man more agony than a real crime. We recognise +the same influence in the burning sense of shame which most of us have +felt, even after the interval of years, when calling to mind some +accidental breach of a trifling, though fixed, rule of etiquette. The +judgment of the community will generally be guided by some rude experience +of what is best in the long run for all the members; but this judgment will +not rarely err from ignorance and weak powers of reasoning. Hence the +strangest customs and superstitions, in complete opposition to the true +welfare and happiness of mankind, have become all-powerful throughout the +world. We see this in the horror felt by a Hindoo who breaks his caste, +and in many other such cases. It would be difficult to distinguish between +the remorse felt by a Hindoo who has yielded to the temptation of eating +unclean food, from that felt after committing a theft; but the former would +probably be the more severe. + +How so many absurd rules of conduct, as well as so many absurd religious +beliefs, have originated, we do not know; nor how it is that they have +become, in all quarters of the world, so deeply impressed on the mind of +men; but it is worthy of remark that a belief constantly inculcated during +the early years of life, whilst the brain is impressible, appears to +acquire almost the nature of an instinct; and the very essence of an +instinct is that it is followed independently of reason. Neither can we +say why certain admirable virtues, such as the love of truth, are much more +highly appreciated by some savage tribes than by others (43. Good +instances are given by Mr. Wallace in 'Scientific Opinion,' Sept. 15, 1869; +and more fully in his 'Contributions to the Theory of Natural Selection,' +1870, p. 353.); nor, again, why similar differences prevail even amongst +highly civilised nations. Knowing how firmly fixed many strange customs +and superstitions have become, we need feel no surprise that the self- +regarding virtues, supported as they are by reason, should now appear to us +so natural as to be thought innate, although they were not valued by man in +his early condition. + +Not withstanding many sources of doubt, man can generally and readily +distinguish between the higher and lower moral rules. The higher are +founded on the social instincts, and relate to the welfare of others. They +are supported by the approbation of our fellow-men and by reason. The +lower rules, though some of them when implying self-sacrifice hardly +deserve to be called lower, relate chiefly to self, and arise from public +opinion, matured by experience and cultivation; for they are not practised +by rude tribes. + +As man advances in civilisation, and small tribes are united into larger +communities, the simplest reason would tell each individual that he ought +to extend his social instincts and sympathies to all the members of the +same nation, though personally unknown to him. This point being once +reached, there is only an artificial barrier to prevent his sympathies +extending to the men of all nations and races. If, indeed, such men are +separated from him by great differences in appearance or habits, experience +unfortunately shews us how long it is, before we look at them as our +fellow-creatures. Sympathy beyond the confines of man, that is, humanity +to the lower animals, seems to be one of the latest moral acquisitions. It +is apparently unfelt by savages, except towards their pets. How little the +old Romans knew of it is shewn by their abhorrent gladiatorial exhibitions. +The very idea of humanity, as far as I could observe, was new to most of +the Gauchos of the Pampas. This virtue, one of the noblest with which man +is endowed, seems to arise incidentally from our sympathies becoming more +tender and more widely diffused, until they are extended to all sentient +beings. As soon as this virtue is honoured and practised by some few men, +it spreads through instruction and example to the young, and eventually +becomes incorporated in public opinion. + +The highest possible stage in moral culture is when we recognise that we +ought to control our thoughts, and "not even in inmost thought to think +again the sins that made the past so pleasant to us." (44. Tennyson, +Idylls of the King, p. 244.) Whatever makes any bad action familiar to the +mind, renders its performance by so much the easier. As Marcus Aurelius +long ago said, "Such as are thy habitual thoughts, such also will be the +character of thy mind; for the soul is dyed by the thoughts." (45. 'The +Thoughts of the Emperor M. Aurelius Antoninus,' English translation, 2nd +edit., 1869. p. 112. Marcus Aurelius ws born A.D. 121.) + +Our great philosopher, Herbert Spencer, has recently explained his views on +the moral sense. He says (46. Letter to Mr. Mill in Bain's 'Mental and +Moral Science,' 1868, p. 722.), "I believe that the experiences of utility +organised and consolidated through all past generations of the human race, +have been producing corresponding modifications, which, by continued +transmission and accumulation, have become in us certain faculties of moral +intuition--certain emotions responding to right and wrong conduct, which +have no apparent basis in the individual experiences of utility." There is +not the least inherent improbability, as it seems to me, in virtuous +tendencies being more or less strongly inherited; for, not to mention the +various dispositions and habits transmitted by many of our domestic animals +to their offspring, I have heard of authentic cases in which a desire to +steal and a tendency to lie appeared to run in families of the upper ranks; +and as stealing is a rare crime in the wealthy classes, we can hardly +account by accidental coincidence for the tendency occurring in two or +three members of the same family. If bad tendencies are transmitted, it is +probable that good ones are likewise transmitted. That the state of the +body by affecting the brain, has great influence on the moral tendencies is +known to most of those who have suffered from chronic derangements of the +digestion or liver. The same fact is likewise shewn by the "perversion or +destruction of the moral sense being often one of the earliest symptoms of +mental derangement" (47. Maudsley, 'Body and Mind,' 1870, p. 60.); and +insanity is notoriously often inherited. Except through the principle of +the transmission of moral tendencies, we cannot understand the differences +believed to exist in this respect between the various races of mankind. + +Even the partial transmission of virtuous tendencies would be an immense +assistance to the primary impulse derived directly and indirectly from the +social instincts. Admitting for a moment that virtuous tendencies are +inherited, it appears probable, at least in such cases as chastity, +temperance, humanity to animals, etc., that they become first impressed on +the mental organization through habit, instruction and example, continued +during several generations in the same family, and in a quite subordinate +degree, or not at all, by the individuals possessing such virtues having +succeeded best in the struggle for life. My chief source of doubt with +respect to any such inheritance, is that senseless customs, superstitions, +and tastes, such as the horror of a Hindoo for unclean food, ought on the +same principle to be transmitted. I have not met with any evidence in +support of the transmission of superstitious customs or senseless habits, +although in itself it is perhaps not less probable than that animals should +acquire inherited tastes for certain kinds of food or fear of certain foes. + +Finally the social instincts, which no doubt were acquired by man as by the +lower animals for the good of the community, will from the first have given +to him some wish to aid his fellows, some feeling of sympathy, and have +compelled him to regard their approbation and disapprobation. Such +impulses will have served him at a very early period as a rude rule of +right and wrong. But as man gradually advanced in intellectual power, and +was enabled to trace the more remote consequences of his actions; as he +acquired sufficient knowledge to reject baneful customs and superstitions; +as he regarded more and more, not only the welfare, but the happiness of +his fellow-men; as from habit, following on beneficial experience, +instruction and example, his sympathies became more tender and widely +diffused, extending to men of all races, to the imbecile, maimed, and other +useless members of society, and finally to the lower animals,--so would the +standard of his morality rise higher and higher. And it is admitted by +moralists of the derivative school and by some intuitionists, that the +standard of morality has risen since an early period in the history of man. +(48. A writer in the 'North British Review' (July 1869, p. 531), well +capable of forming a sound judgment, expresses himself strongly in favour +of this conclusion. Mr. Lecky ('History of Morals,' vol. i. p. 143) seems +to a certain extent to coincide therein.) + +As a struggle may sometimes be seen going on between the various instincts +of the lower animals, it is not surprising that there should be a struggle +in man between his social instincts, with their derived virtues, and his +lower, though momentarily stronger impulses or desires. This, as Mr. +Galton (49. See his remarkable work on 'Hereditary Genius,' 1869, p. 349. +The Duke of Argyll ('Primeval Man,' 1869, p. 188) has some good remarks on +the contest in man's nature between right and wrong.) has remarked, is all +the less surprising, as man has emerged from a state of barbarism within a +comparatively recent period. After having yielded to some temptation we +feel a sense of dissatisfaction, shame, repentance, or remorse, analogous +to the feelings caused by other powerful instincts or desires, when left +unsatisfied or baulked. We compare the weakened impression of a past +temptation with the ever present social instincts, or with habits, gained +in early youth and strengthened during our whole lives, until they have +become almost as strong as instincts. If with the temptation still before +us we do not yield, it is because either the social instinct or some custom +is at the moment predominant, or because we have learnt that it will appear +to us hereafter the stronger, when compared with the weakened impression of +the temptation, and we realise that its violation would cause us suffering. +Looking to future generations, there is no cause to fear that the social +instincts will grow weaker, and we may expect that virtuous habits will +grow stronger, becoming perhaps fixed by inheritance. In this case the +struggle between our higher and lower impulses will be less severe, and +virtue will be triumphant. + +SUMMARY OF THE LAST TWO CHAPTERS. + +There can be no doubt that the difference between the mind of the lowest +man and that of the highest animal is immense. An anthropomorphous ape, if +he could take a dispassionate view of his own case, would admit that though +he could form an artful plan to plunder a garden--though he could use +stones for fighting or for breaking open nuts, yet that the thought of +fashioning a stone into a tool was quite beyond his scope. Still less, as +he would admit, could he follow out a train of metaphysical reasoning, or +solve a mathematical problem, or reflect on God, or admire a grand natural +scene. Some apes, however, would probably declare that they could and did +admire the beauty of the coloured skin and fur of their partners in +marriage. They would admit, that though they could make other apes +understand by cries some of their perceptions and simpler wants, the notion +of expressing definite ideas by definite sounds had never crossed their +minds. They might insist that they were ready to aid their fellow-apes of +the same troop in many ways, to risk their lives for them, and to take +charge of their orphans; but they would be forced to acknowledge that +disinterested love for all living creatures, the most noble attribute of +man, was quite beyond their comprehension. + +Nevertheless the difference in mind between man and the higher animals, +great as it is, certainly is one of degree and not of kind. We have seen +that the senses and intuitions, the various emotions and faculties, such as +love, memory, attention, curiosity, imitation, reason, etc., of which man +boasts, may be found in an incipient, or even sometimes in a well-developed +condition, in the lower animals. They are also capable of some inherited +improvement, as we see in the domestic dog compared with the wolf or +jackal. If it could be proved that certain high mental powers, such as the +formation of general concepts, self-consciousness, etc., were absolutely +peculiar to man, which seems extremely doubtful, it is not improbable that +these qualities are merely the incidental results of other highly-advanced +intellectual faculties; and these again mainly the result of the continued +use of a perfect language. At what age does the new-born infant possess +the power of abstraction, or become self-conscious, and reflect on its own +existence? We cannot answer; nor can we answer in regard to the ascending +organic scale. The half-art, half-instinct of language still bears the +stamp of its gradual evolution. The ennobling belief in God is not +universal with man; and the belief in spiritual agencies naturally follows +from other mental powers. The moral sense perhaps affords the best and +highest distinction between man and the lower animals; but I need say +nothing on this head, as I have so lately endeavoured to shew that the +social instincts,--the prime principle of man's moral constitution (50. +'The Thoughts of Marcus Aurelius,' etc., p. 139.)--with the aid of active +intellectual powers and the effects of habit, naturally lead to the golden +rule, "As ye would that men should do to you, do ye to them likewise;" and +this lies at the foundation of morality. + +In the next chapter I shall make some few remarks on the probable steps and +means by which the several mental and moral faculties of man have been +gradually evolved. That such evolution is at least possible, ought not to +be denied, for we daily see these faculties developing in every infant; and +we may trace a perfect gradation from the mind of an utter idiot, lower +than that of an animal low in the scale, to the mind of a Newton. + + +CHAPTER V. + +ON THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL FACULTIES DURING PRIMEVAL +AND CIVILISED TIMES. + +Advancement of the intellectual powers through natural selection-- +Importance of imitation--Social and moral faculties--Their development +within the limits of the same tribe--Natural selection as affecting +civilised nations--Evidence that civilised nations were once barbarous. + +The subjects to be discussed in this chapter are of the highest interest, +but are treated by me in an imperfect and fragmentary manner. Mr. Wallace, +in an admirable paper before referred to (1. Anthropological Review, May +1864, p. clviii.), argues that man, after he had partially acquired those +intellectual and moral faculties which distinguish him from the lower +animals, would have been but little liable to bodily modifications through +natural selection or any other means. For man is enabled through his +mental faculties "to keep with an unchanged body in harmony with the +changing universe." He has great power of adapting his habits to new +conditions of life. He invents weapons, tools, and various stratagems to +procure food and to defend himself. When he migrates into a colder climate +he uses clothes, builds sheds, and makes fires; and by the aid of fire +cooks food otherwise indigestible. He aids his fellow-men in many ways, +and anticipates future events. Even at a remote period he practised some +division of labour. + +The lower animals, on the other hand, must have their bodily structure +modified in order to survive under greatly changed conditions. They must +be rendered stronger, or acquire more effective teeth or claws, for defence +against new enemies; or they must be reduced in size, so as to escape +detection and danger. When they migrate into a colder climate, they must +become clothed with thicker fur, or have their constitutions altered. If +they fail to be thus modified, they will cease to exist. + +The case, however, is widely different, as Mr. Wallace has with justice +insisted, in relation to the intellectual and moral faculties of man. +These faculties are variable; and we have every reason to believe that the +variations tend to be inherited. Therefore, if they were formerly of high +importance to primeval man and to his ape-like progenitors, they would have +been perfected or advanced through natural selection. Of the high +importance of the intellectual faculties there can be no doubt, for man +mainly owes to them his predominant position in the world. We can see, +that in the rudest state of society, the individuals who were the most +sagacious, who invented and used the best weapons or traps, and who were +best able to defend themselves, would rear the greatest number of +offspring. The tribes, which included the largest number of men thus +endowed, would increase in number and supplant other tribes. Numbers +depend primarily on the means of subsistence, and this depends partly on +the physical nature of the country, but in a much higher degree on the arts +which are there practised. As a tribe increases and is victorious, it is +often still further increased by the absorption of other tribes. (2. +After a time the members or tribes which are absorbed into another tribe +assume, as Sir Henry Maine remarks ('Ancient Law,' 1861, p. 131), that they +are the co-descendants of the same ancestors.) The stature and strength of +the men of a tribe are likewise of some importance for its success, and +these depend in part on the nature and amount of the food which can be +obtained. In Europe the men of the Bronze period were supplanted by a race +more powerful, and, judging from their sword-handles, with larger hands (3. +Morlot, 'Soc. Vaud. Sc. Nat.' 1860, p. 294.); but their success was +probably still more due to their superiority in the arts. + +All that we know about savages, or may infer from their traditions and from +old monuments, the history of which is quite forgotten by the present +inhabitants, shew that from the remotest times successful tribes have +supplanted other tribes. Relics of extinct or forgotten tribes have been +discovered throughout the civilised regions of the earth, on the wild +plains of America, and on the isolated islands in the Pacific Ocean. At +the present day civilised nations are everywhere supplanting barbarous +nations, excepting where the climate opposes a deadly barrier; and they +succeed mainly, though not exclusively, through their arts, which are the +products of the intellect. It is, therefore, highly probable that with +mankind the intellectual faculties have been mainly and gradually perfected +through natural selection; and this conclusion is sufficient for our +purpose. Undoubtedly it would be interesting to trace the development of +each separate faculty from the state in which it exists in the lower +animals to that in which it exists in man; but neither my ability nor +knowledge permits the attempt. + +It deserves notice that, as soon as the progenitors of man became social +(and this probably occurred at a very early period), the principle of +imitation, and reason, and experience would have increased, and much +modified the intellectual powers in a way, of which we see only traces in +the lower animals. Apes are much given to imitation, as are the lowest +savages; and the simple fact previously referred to, that after a time no +animal can be caught in the same place by the same sort of trap, shews that +animals learn by experience, and imitate the caution of others. Now, if +some one man in a tribe, more sagacious than the others, invented a new +snare or weapon, or other means of attack or defence, the plainest self- +interest, without the assistance of much reasoning power, would prompt the +other members to imitate him; and all would thus profit. The habitual +practice of each new art must likewise in some slight degree strengthen the +intellect. If the new invention were an important one, the tribe would +increase in number, spread, and supplant other tribes. In a tribe thus +rendered more numerous there would always be a rather greater chance of the +birth of other superior and inventive members. If such men left children +to inherit their mental superiority, the chance of the birth of still more +ingenious members would be somewhat better, and in a very small tribe +decidedly better. Even if they left no children, the tribe would still +include their blood-relations; and it has been ascertained by +agriculturists (4. I have given instances in my Variation of Animals under +Domestication, vol. ii. p. 196.) that by preserving and breeding from the +family of an animal, which when slaughtered was found to be valuable, the +desired character has been obtained. + +Turning now to the social and moral faculties. In order that primeval men, +or the ape-like progenitors of man, should become social, they must have +acquired the same instinctive feelings, which impel other animals to live +in a body; and they no doubt exhibited the same general disposition. They +would have felt uneasy when separated from their comrades, for whom they +would have felt some degree of love; they would have warned each other of +danger, and have given mutual aid in attack or defence. All this implies +some degree of sympathy, fidelity, and courage. Such social qualities, the +paramount importance of which to the lower animals is disputed by no one, +were no doubt acquired by the progenitors of man in a similar manner, +namely, through natural selection, aided by inherited habit. When two +tribes of primeval man, living in the same country, came into competition, +if (other circumstances being equal) the one tribe included a great number +of courageous, sympathetic and faithful members, who were always ready to +warn each other of danger, to aid and defend each other, this tribe would +succeed better and conquer the other. Let it be borne in mind how all- +important in the never-ceasing wars of savages, fidelity and courage must +be. The advantage which disciplined soldiers have over undisciplined +hordes follows chiefly from the confidence which each man feels in his +comrades. Obedience, as Mr. Bagehot has well shewn (5. See a remarkable +series of articles on 'Physics and Politics,' in the 'Fortnightly Review,' +Nov. 1867; April 1, 1868; July 1, 1869, since separately published.), is of +the highest value, for any form of government is better than none. Selfish +and contentious people will not cohere, and without coherence nothing can +be effected. A tribe rich in the above qualities would spread and be +victorious over other tribes: but in the course of time it would, judging +from all past history, be in its turn overcome by some other tribe still +more highly endowed. Thus the social and moral qualities would tend slowly +to advance and be diffused throughout the world. + +But it may be asked, how within the limits of the same tribe did a large +number of members first become endowed with these social and moral +qualities, and how was the standard of excellence raised? It is extremely +doubtful whether the offspring of the more sympathetic and benevolent +parents, or of those who were the most faithful to their comrades, would be +reared in greater numbers than the children of selfish and treacherous +parents belonging to the same tribe. He who was ready to sacrifice his +life, as many a savage has been, rather than betray his comrades, would +often leave no offspring to inherit his noble nature. The bravest men, who +were always willing to come to the front in war, and who freely risked +their lives for others, would on an average perish in larger numbers than +other men. Therefore, it hardly seems probable, that the number of men +gifted with such virtues, or that the standard of their excellence, could +be increased through natural selection, that is, by the survival of the +fittest; for we are not here speaking of one tribe being victorious over +another. + +Although the circumstances, leading to an increase in the number of those +thus endowed within the same tribe, are too complex to be clearly followed +out, we can trace some of the probable steps. In the first place, as the +reasoning powers and foresight of the members became improved, each man +would soon learn that if he aided his fellow-men, he would commonly receive +aid in return. From this low motive he might acquire the habit of aiding +his fellows; and the habit of performing benevolent actions certainly +strengthens the feeling of sympathy which gives the first impulse to +benevolent actions. Habits, moreover, followed during many generations +probably tend to be inherited. + +But another and much more powerful stimulus to the development of the +social virtues, is afforded by the praise and the blame of our fellow-men. +To the instinct of sympathy, as we have already seen, it is primarily due, +that we habitually bestow both praise and blame on others, whilst we love +the former and dread the latter when applied to ourselves; and this +instinct no doubt was originally acquired, like all the other social +instincts, through natural selection. At how early a period the +progenitors of man in the course of their development, became capable of +feeling and being impelled by, the praise or blame of their fellow- +creatures, we cannot of course say. But it appears that even dogs +appreciate encouragement, praise, and blame. The rudest savages feel the +sentiment of glory, as they clearly shew by preserving the trophies of +their prowess, by their habit of excessive boasting, and even by the +extreme care which they take of their personal appearance and decorations; +for unless they regarded the opinion of their comrades, such habits would +be senseless. + +They certainly feel shame at the breach of some of their lesser rules, and +apparently remorse, as shewn by the case of the Australian who grew thin +and could not rest from having delayed to murder some other woman, so as to +propitiate his dead wife's spirit. Though I have not met with any other +recorded case, it is scarcely credible that a savage, who will sacrifice +his life rather than betray his tribe, or one who will deliver himself up +as a prisoner rather than break his parole (6. Mr. Wallace gives cases in +his 'Contributions to the Theory of Natural Selection,' 1870, p. 354.), +would not feel remorse in his inmost soul, if he had failed in a duty, +which he held sacred. + +We may therefore conclude that primeval man, at a very remote period, was +influenced by the praise and blame of his fellows. It is obvious, that the +members of the same tribe would approve of conduct which appeared to them +to be for the general good, and would reprobate that which appeared evil. +To do good unto others--to do unto others as ye would they should do unto +you--is the foundation-stone of morality. It is, therefore, hardly +possible to exaggerate the importance during rude times of the love of +praise and the dread of blame. A man who was not impelled by any deep, +instinctive feeling, to sacrifice his life for the good of others, yet was +roused to such actions by a sense of glory, would by his example excite the +same wish for glory in other men, and would strengthen by exercise the +noble feeling of admiration. He might thus do far more good to his tribe +than by begetting offspring with a tendency to inherit his own high +character. + +With increased experience and reason, man perceives the more remote +consequences of his actions, and the self-regarding virtues, such as +temperance, chastity, etc., which during early times are, as we have before +seen, utterly disregarded, come to be highly esteemed or even held sacred. +I need not, however, repeat what I have said on this head in the fourth +chapter. Ultimately our moral sense or conscience becomes a highly complex +sentiment--originating in the social instincts, largely guided by the +approbation of our fellow-men, ruled by reason, self-interest, and in later +times by deep religious feelings, and confirmed by instruction and habit. + +It must not be forgotten that although a high standard of morality gives +but a slight or no advantage to each individual man and his children over +the other men of the same tribe, yet that an increase in the number of +well-endowed men and an advancement in the standard of morality will +certainly give an immense advantage to one tribe over another. A tribe +including many members who, from possessing in a high degree the spirit of +patriotism, fidelity, obedience, courage, and sympathy, were always ready +to aid one another, and to sacrifice themselves for the common good, would +be victorious over most other tribes; and this would be natural selection. +At all times throughout the world tribes have supplanted other tribes; and +as morality is one important element in their success, the standard of +morality and the number of well-endowed men will thus everywhere tend to +rise and increase. + +It is, however, very difficult to form any judgment why one particular +tribe and not another has been successful and has risen in the scale of +civilisation. Many savages are in the same condition as when first +discovered several centuries ago. As Mr. Bagehot has remarked, we are apt +to look at progress as normal in human society; but history refutes this. +The ancients did not even entertain the idea, nor do the Oriental nations +at the present day. According to another high authority, Sir Henry Maine +(7. 'Ancient Law,' 1861, p. 22. For Mr. Bagehot's remarks, 'Fortnightly +Review,' April 1, 1868, p. 452.), "the greatest part of mankind has never +shewn a particle of desire that its civil institutions should be improved." +Progress seems to depend on many concurrent favourable conditions, far too +complex to be followed out. But it has often been remarked, that a cool +climate, from leading to industry and to the various arts, has been highly +favourable thereto. The Esquimaux, pressed by hard necessity, have +succeeded in many ingenious inventions, but their climate has been too +severe for continued progress. Nomadic habits, whether over wide plains, +or through the dense forests of the tropics, or along the shores of the +sea, have in every case been highly detrimental. Whilst observing the +barbarous inhabitants of Tierra del Fuego, it struck me that the possession +of some property, a fixed abode, and the union of many families under a +chief, were the indispensable requisites for civilisation. Such habits +almost necessitate the cultivation of the ground; and the first steps in +cultivation would probably result, as I have elsewhere shewn (8. 'The +Variation of Animals and Plants under Domestication,' vol. i. p. 309.), +from some such accident as the seeds of a fruit-tree falling on a heap of +refuse, and producing an unusually fine variety. The problem, however, of +the first advance of savages towards civilisation is at present much too +difficult to be solved. + +NATURAL SELECTION AS AFFECTING CIVILISED NATIONS. + +I have hitherto only considered the advancement of man from a semi-human +condition to that of the modern savage. But some remarks on the action of +natural selection on civilised nations may be worth adding. This subject +has been ably discussed by Mr. W.R. Greg (9. 'Fraser's Magazine,' Sept. +1868, p. 353. This article seems to have struck many persons, and has +given rise to two remarkable essays and a rejoinder in the 'Spectator,' +Oct. 3rd and 17th, 1868. It has also been discussed in the 'Quarterly +Journal of Science,' 1869, p. 152, and by Mr. Lawson Tait in the 'Dublin +Quarterly Journal of Medical Science,' Feb. 1869, and by Mr. E. Ray +Lankester in his 'Comparative Longevity,' 1870, p. 128. Similar views +appeared previously in the 'Australasian,' July 13, 1867. I have borrowed +ideas from several of these writers.), and previously by Mr. Wallace and +Mr. Galton. (10. For Mr. Wallace, see 'Anthropological Review,' as before +cited. Mr. Galton in 'Macmillan's Magazine,' Aug. 1865, p. 318; also his +great work, 'Hereditary Genius,' 1870.) Most of my remarks are taken from +these three authors. With savages, the weak in body or mind are soon +eliminated; and those that survive commonly exhibit a vigorous state of +health. We civilised men, on the other hand, do our utmost to check the +process of elimination; we build asylums for the imbecile, the maimed, and +the sick; we institute poor-laws; and our medical men exert their utmost +skill to save the life of every one to the last moment. There is reason to +believe that vaccination has preserved thousands, who from a weak +constitution would formerly have succumbed to small-pox. Thus the weak +members of civilised societies propagate their kind. No one who has +attended to the breeding of domestic animals will doubt that this must be +highly injurious to the race of man. It is surprising how soon a want of +care, or care wrongly directed, leads to the degeneration of a domestic +race; but excepting in the case of man himself, hardly any one is so +ignorant as to allow his worst animals to breed. + +The aid which we feel impelled to give to the helpless is mainly an +incidental result of the instinct of sympathy, which was originally +acquired as part of the social instincts, but subsequently rendered, in the +manner previously indicated, more tender and more widely diffused. Nor +could we check our sympathy, even at the urging of hard reason, without +deterioration in the noblest part of our nature. The surgeon may harden +himself whilst performing an operation, for he knows that he is acting for +the good of his patient; but if we were intentionally to neglect the weak +and helpless, it could only be for a contingent benefit, with an +overwhelming present evil. We must therefore bear the undoubtedly bad +effects of the weak surviving and propagating their kind; but there appears +to be at least one check in steady action, namely that the weaker and +inferior members of society do not marry so freely as the sound; and this +check might be indefinitely increased by the weak in body or mind +refraining from marriage, though this is more to be hoped for than +expected. + +In every country in which a large standing army is kept up, the finest +young men are taken by the conscription or are enlisted. They are thus +exposed to early death during war, are often tempted into vice, and are +prevented from marrying during the prime of life. On the other hand the +shorter and feebler men, with poor constitutions, are left at home, and +consequently have a much better chance of marrying and propagating their +kind. (11. Prof. H. Fick ('Einfluss der Naturwissenschaft auf das Recht,' +June 1872) has some good remarks on this head, and on other such points.) + +Man accumulates property and bequeaths it to his children, so that the +children of the rich have an advantage over the poor in the race for +success, independently of bodily or mental superiority. On the other hand, +the children of parents who are short-lived, and are therefore on an +average deficient in health and vigour, come into their property sooner +than other children, and will be likely to marry earlier, and leave a +larger number of offspring to inherit their inferior constitutions. But +the inheritance of property by itself is very far from an evil; for without +the accumulation of capital the arts could not progress; and it is chiefly +through their power that the civilised races have extended, and are now +everywhere extending their range, so as to take the place of the lower +races. Nor does the moderate accumulation of wealth interfere with the +process of selection. When a poor man becomes moderately rich, his +children enter trades or professions in which there is struggle enough, so +that the able in body and mind succeed best. The presence of a body of +well-instructed men, who have not to labour for their daily bread, is +important to a degree which cannot be over-estimated; as all high +intellectual work is carried on by them, and on such work, material +progress of all kinds mainly depends, not to mention other and higher +advantages. No doubt wealth when very great tends to convert men into +useless drones, but their number is never large; and some degree of +elimination here occurs, for we daily see rich men, who happen to be fools +or profligate, squandering away their wealth. + +Primogeniture with entailed estates is a more direct evil, though it may +formerly have been a great advantage by the creation of a dominant class, +and any government is better than none. Most eldest sons, though they may +be weak in body or mind, marry, whilst the younger sons, however superior +in these respects, do not so generally marry. Nor can worthless eldest +sons with entailed estates squander their wealth. But here, as elsewhere, +the relations of civilised life are so complex that some compensatory +checks intervene. The men who are rich through primogeniture are able to +select generation after generation the more beautiful and charming women; +and these must generally be healthy in body and active in mind. The evil +consequences, such as they may be, of the continued preservation of the +same line of descent, without any selection, are checked by men of rank +always wishing to increase their wealth and power; and this they effect by +marrying heiresses. But the daughters of parents who have produced single +children, are themselves, as Mr. Galton (12. 'Hereditary Genius,' 1870, pp. +132-140.) has shewn, apt to be sterile; and thus noble families are +continually cut off in the direct line, and their wealth flows into some +side channel; but unfortunately this channel is not determined by +superiority of any kind. + +Although civilisation thus checks in many ways the action of natural +selection, it apparently favours the better development of the body, by +means of good food and the freedom from occasional hardships. This may be +inferred from civilised men having been found, wherever compared, to be +physically stronger than savages. (13. Quatrefages, 'Revue des Cours +Scientifiques,' 1867-68, p. 659.) They appear also to have equal powers of +endurance, as has been proved in many adventurous expeditions. Even the +great luxury of the rich can be but little detrimental; for the expectation +of life of our aristocracy, at all ages and of both sexes, is very little +inferior to that of healthy English lives in the lower classes. (14. +See the fifth and sixth columns, compiled from good authorities, in the +table given in Mr. E.R. Lankester's 'Comparative Longevity,' 1870, p. 115.) + +We will now look to the intellectual faculties. If in each grade of +society the members were divided into two equal bodies, the one including +the intellectually superior and the other the inferior, there can be little +doubt that the former would succeed best in all occupations, and rear a +greater number of children. Even in the lowest walks of life, skill and +ability must be of some advantage; though in many occupations, owing to the +great division of labour, a very small one. Hence in civilised nations +there will be some tendency to an increase both in the number and in the +standard of the intellectually able. But I do not wish to assert that this +tendency may not be more than counterbalanced in other ways, as by the +multiplication of the reckless and improvident; but even to such as these, +ability must be some advantage. + +It has often been objected to views like the foregoing, that the most +eminent men who have ever lived have left no offspring to inherit their +great intellect. Mr. Galton says, "I regret I am unable to solve the +simple question whether, and how far, men and women who are prodigies of +genius are infertile. I have, however, shewn that men of eminence are by +no means so." (15. 'Hereditary Genius,' 1870, p. 330.) Great lawgivers, +the founders of beneficent religions, great philosophers and discoverers in +science, aid the progress of mankind in a far higher degree by their works +than by leaving a numerous progeny. In the case of corporeal structures, +it is the selection of the slightly better-endowed and the elimination of +the slightly less well-endowed individuals, and not the preservation of +strongly-marked and rare anomalies, that leads to the advancement of a +species. (16. 'Origin of Species' (fifth edition, 1869), p. 104.) So it +will be with the intellectual faculties, since the somewhat abler men in +each grade of society succeed rather better than the less able, and +consequently increase in number, if not otherwise prevented. When in any +nation the standard of intellect and the number of intellectual men have +increased, we may expect from the law of the deviation from an average, +that prodigies of genius will, as shewn by Mr. Galton, appear somewhat more +frequently than before. + +In regard to the moral qualities, some elimination of the worst +dispositions is always in progress even in the most civilised nations. +Malefactors are executed, or imprisoned for long periods, so that they +cannot freely transmit their bad qualities. Melancholic and insane persons +are confined, or commit suicide. Violent and quarrelsome men often come to +a bloody end. The restless who will not follow any steady occupation--and +this relic of barbarism is a great check to civilisation (17. 'Hereditary +Genius,' 1870, p. 347.)--emigrate to newly-settled countries; where they +prove useful pioneers. Intemperance is so highly destructive, that the +expectation of life of the intemperate, at the age of thirty for instance, +is only 13.8 years; whilst for the rural labourers of England at the same +age it is 40.59 years. (18. E. Ray Lankester, 'Comparative Longevity,' +1870, p. 115. The table of the intemperate is from Neison's 'Vital +Statistics.' In regard to profligacy, see Dr. Farr, 'Influence of Marriage +on Mortality,' 'Nat. Assoc. for the Promotion of Social Science,' 1858.) +Profligate women bear few children, and profligate men rarely marry; both +suffer from disease. In the breeding of domestic animals, the elimination +of those individuals, though few in number, which are in any marked manner +inferior, is by no means an unimportant element towards success. This +especially holds good with injurious characters which tend to reappear +through reversion, such as blackness in sheep; and with mankind some of the +worst dispositions, which occasionally without any assignable cause make +their appearance in families, may perhaps be reversions to a savage state, +from which we are not removed by very many generations. This view seems +indeed recognised in the common expression that such men are the black +sheep of the family. + +With civilised nations, as far as an advanced standard of morality, and an +increased number of fairly good men are concerned, natural selection +apparently effects but little; though the fundamental social instincts were +originally thus gained. But I have already said enough, whilst treating of +the lower races, on the causes which lead to the advance of morality, +namely, the approbation of our fellow-men--the strengthening of our +sympathies by habit--example and imitation--reason--experience, and even +self-interest--instruction during youth, and religious feelings. + +A most important obstacle in civilised countries to an increase in the +number of men of a superior class has been strongly insisted on by Mr. Greg +and Mr. Galton (19. 'Fraser's Magazine,' Sept. 1868, p. 353. 'Macmillan's +Magazine,' Aug. 1865, p. 318. The Rev. F.W. Farrar ('Fraser's Magazine,' +Aug. 1870, p. 264) takes a different view.), namely, the fact that the very +poor and reckless, who are often degraded by vice, almost invariably marry +early, whilst the careful and frugal, who are generally otherwise virtuous, +marry late in life, so that they may be able to support themselves and +their children in comfort. Those who marry early produce within a given +period not only a greater number of generations, but, as shewn by Dr. +Duncan (20. 'On the Laws of the Fertility of Women,' in 'Transactions of +the Royal Society,' Edinburgh, vol. xxiv. p. 287; now published separately +under the title of 'Fecundity, Fertility, and Sterility,' 1871. See, also, +Mr. Galton, 'Hereditary Genius,' pp. 352-357, for observations to the above +effect.), they produce many more children. The children, moreover, that +are borne by mothers during the prime of life are heavier and larger, and +therefore probably more vigorous, than those born at other periods. Thus +the reckless, degraded, and often vicious members of society, tend to +increase at a quicker rate than the provident and generally virtuous +members. Or as Mr. Greg puts the case: "The careless, squalid, unaspiring +Irishman multiplies like rabbits: the frugal, foreseeing, self-respecting, +ambitious Scot, stern in his morality, spiritual in his faith, sagacious +and disciplined in his intelligence, passes his best years in struggle and +in celibacy, marries late, and leaves few behind him. Given a land +originally peopled by a thousand Saxons and a thousand Celts--and in a +dozen generations five-sixths of the population would be Celts, but five- +sixths of the property, of the power, of the intellect, would belong to the +one-sixth of Saxons that remained. In the eternal 'struggle for +existence,' it would be the inferior and LESS favoured race that had +prevailed--and prevailed by virtue not of its good qualities but of its +faults." + +There are, however, some checks to this downward tendency. We have seen +that the intemperate suffer from a high rate of mortality, and the +extremely profligate leave few offspring. The poorest classes crowd into +towns, and it has been proved by Dr. Stark from the statistics of ten years +in Scotland (21. 'Tenth Annual Report of Births, Deaths, etc., in +Scotland,' 1867, p. xxix.), that at all ages the death-rate is higher in +towns than in rural districts, "and during the first five years of life the +town death-rate is almost exactly double that of the rural districts." As +these returns include both the rich and the poor, no doubt more than twice +the number of births would be requisite to keep up the number of the very +poor inhabitants in the towns, relatively to those in the country. With +women, marriage at too early an age is highly injurious; for it has been +found in France that, "Twice as many wives under twenty die in the year, as +died out of the same number of the unmarried." The mortality, also, of +husbands under twenty is "excessively high" (22. These quotations are +taken from our highest authority on such questions, namely, Dr. Farr, in +his paper 'On the Influence of Marriage on the Mortality of the French +People,' read before the Nat. Assoc. for the Promotion of Social Science, +1858.), but what the cause of this may be, seems doubtful. Lastly, if the +men who prudently delay marrying until they can bring up their families in +comfort, were to select, as they often do, women in the prime of life, the +rate of increase in the better class would be only slightly lessened. + +It was established from an enormous body of statistics, taken during 1853, +that the unmarried men throughout France, between the ages of twenty and +eighty, die in a much larger proportion than the married: for instance, +out of every 1000 unmarried men, between the ages of twenty and thirty, +11.3 annually died, whilst of the married, only 6.5 died. (23. Dr. Farr, +ibid. The quotations given below are extracted from the same striking +paper.) A similar law was proved to hold good, during the years 1863 and +1864, with the entire population above the age of twenty in Scotland: for +instance, out of every 1000 unmarried men, between the ages of twenty and +thirty, 14.97 annually died, whilst of the married only 7.24 died, that is +less than half. (24. I have taken the mean of the quinquennial means, +given in 'The Tenth Annual Report of Births, Deaths, etc., in Scotland,' +1867. The quotation from Dr. Stark is copied from an article in the 'Daily +News,' Oct. 17, 1868, which Dr. Farr considers very carefully written.) +Dr. Stark remarks on this, "Bachelorhood is more destructive to life than +the most unwholesome trades, or than residence in an unwholesome house or +district where there has never been the most distant attempt at sanitary +improvement." He considers that the lessened mortality is the direct +result of "marriage, and the more regular domestic habits which attend that +state." He admits, however, that the intemperate, profligate, and criminal +classes, whose duration of life is low, do not commonly marry; and it must +likewise be admitted that men with a weak constitution, ill health, or any +great infirmity in body or mind, will often not wish to marry, or will be +rejected. Dr. Stark seems to have come to the conclusion that marriage in +itself is a main cause of prolonged life, from finding that aged married +men still have a considerable advantage in this respect over the unmarried +of the same advanced age; but every one must have known instances of men, +who with weak health during youth did not marry, and yet have survived to +old age, though remaining weak, and therefore always with a lessened chance +of life or of marrying. There is another remarkable circumstance which +seems to support Dr. Stark's conclusion, namely, that widows and widowers +in France suffer in comparison with the married a very heavy rate of +mortality; but Dr. Farr attributes this to the poverty and evil habits +consequent on the disruption of the family, and to grief. On the whole we +may conclude with Dr. Farr that the lesser mortality of married than of +unmarried men, which seems to be a general law, "is mainly due to the +constant elimination of imperfect types, and to the skilful selection of +the finest individuals out of each successive generation;" the selection +relating only to the marriage state, and acting on all corporeal, +intellectual, and moral qualities. (25. Dr. Duncan remarks ('Fecundity, +Fertility, etc.' 1871, p. 334) on this subject: "At every age the healthy +and beautiful go over from the unmarried side to the married, leaving the +unmarried columns crowded with the sickly and unfortunate.") We may, +therefore, infer that sound and good men who out of prudence remain for a +time unmarried, do not suffer a high rate of mortality. + +If the various checks specified in the two last paragraphs, and perhaps +others as yet unknown, do not prevent the reckless, the vicious and +otherwise inferior members of society from increasing at a quicker rate +than the better class of men, the nation will retrograde, as has too often +occurred in the history of the world. We must remember that progress is no +invariable rule. It is very difficult to say why one civilised nation +rises, becomes more powerful, and spreads more widely, than another; or why +the same nation progresses more quickly at one time than at another. We +can only say that it depends on an increase in the actual number of the +population, on the number of men endowed with high intellectual and moral +faculties, as well as on their standard of excellence. Corporeal structure +appears to have little influence, except so far as vigour of body leads to +vigour of mind. + +It has been urged by several writers that as high intellectual powers are +advantageous to a nation, the old Greeks, who stood some grades higher in +intellect than any race that has ever existed (26. See the ingenious and +original argument on this subject by Mr. Galton, 'Hereditary Genius,' pp. +340-342.), ought, if the power of natural selection were real, to have +risen still higher in the scale, increased in number, and stocked the whole +of Europe. Here we have the tacit assumption, so often made with respect +to corporeal structures, that there is some innate tendency towards +continued development in mind and body. But development of all kinds +depends on many concurrent favourable circumstances. Natural selection +acts only tentatively. Individuals and races may have acquired certain +indisputable advantages, and yet have perished from failing in other +characters. The Greeks may have retrograded from a want of coherence +between the many small states, from the small size of their whole country, +from the practice of slavery, or from extreme sensuality; for they did not +succumb until "they were enervated and corrupt to the very core." (27. +Mr. Greg, 'Fraser's Magazine,' Sept. 1868, p. 357.) The western nations of +Europe, who now so immeasurably surpass their former savage progenitors, +and stand at the summit of civilisation, owe little or none of their +superiority to direct inheritance from the old Greeks, though they owe much +to the written works of that wonderful people. + +Who can positively say why the Spanish nation, so dominant at one time, has +been distanced in the race. The awakening of the nations of Europe from +the dark ages is a still more perplexing problem. At that early period, as +Mr. Galton has remarked, almost all the men of a gentle nature, those given +to meditation or culture of the mind, had no refuge except in the bosom of +a Church which demanded celibacy (28. 'Hereditary Genius,' 1870, pp. 357- +359. The Rev. F.W. Farrar ('Fraser's Magazine,' Aug. 1870, p. 257) +advances arguments on the other side. Sir C. Lyell had already +('Principles of Geology,' vol. ii. 1868, p. 489), in a striking passage +called attention to the evil influence of the Holy Inquisition in having, +through selection, lowered the general standard of intelligence in +Europe.); and this could hardly fail to have had a deteriorating influence +on each successive generation. During this same period the Holy +Inquisition selected with extreme care the freest and boldest men in order +to burn or imprison them. In Spain alone some of the best men--those who +doubted and questioned, and without doubting there can be no progress--were +eliminated during three centuries at the rate of a thousand a year. The +evil which the Catholic Church has thus effected is incalculable, though no +doubt counterbalanced to a certain, perhaps to a large, extent in other +ways; nevertheless, Europe has progressed at an unparalleled rate. + +The remarkable success of the English as colonists, compared to other +European nations, has been ascribed to their "daring and persistent +energy"; a result which is well illustrated by comparing the progress of +the Canadians of English and French extraction; but who can say how the +English gained their energy? There is apparently much truth in the belief +that the wonderful progress of the United States, as well as the character +of the people, are the results of natural selection; for the more +energetic, restless, and courageous men from all parts of Europe have +emigrated during the last ten or twelve generations to that great country, +and have there succeeded best. (29. Mr. Galton, 'Macmillan's Magazine,' +August 1865, p. 325. See also, 'Nature,' 'On Darwinism and National Life,' +Dec. 1869, p. 184.) Looking to the distant future, I do not think that the +Rev. Mr. Zincke takes an exaggerated view when he says (30. 'Last Winter +in the United States,' 1868, p. 29.): "All other series of events--as that +which resulted in the culture of mind in Greece, and that which resulted in +the empire of Rome--only appear to have purpose and value when viewed in +connection with, or rather as subsidiary to...the great stream of Anglo- +Saxon emigration to the west." Obscure as is the problem of the advance of +civilisation, we can at least see that a nation which produced during a +lengthened period the greatest number of highly intellectual, energetic, +brave, patriotic, and benevolent men, would generally prevail over less +favoured nations. + +Natural selection follows from the struggle for existence; and this from a +rapid rate of increase. It is impossible not to regret bitterly, but +whether wisely is another question, the rate at which man tends to +increase; for this leads in barbarous tribes to infanticide and many other +evils, and in civilised nations to abject poverty, celibacy, and to the +late marriages of the prudent. But as man suffers from the same physical +evils as the lower animals, he has no right to expect an immunity from the +evils consequent on the struggle for existence. Had he not been subjected +during primeval times to natural selection, assuredly he would never have +attained to his present rank. Since we see in many parts of the world +enormous areas of the most fertile land capable of supporting numerous +happy homes, but peopled only by a few wandering savages, it might be +argued that the struggle for existence had not been sufficiently severe to +force man upwards to his highest standard. Judging from all that we know +of man and the lower animals, there has always been sufficient variability +in their intellectual and moral faculties, for a steady advance through +natural selection. No doubt such advance demands many favourable +concurrent circumstances; but it may well be doubted whether the most +favourable would have sufficed, had not the rate of increase been rapid, +and the consequent struggle for existence extremely severe. It even +appears from what we see, for instance, in parts of S. America, that a +people which may be called civilised, such as the Spanish settlers, is +liable to become indolent and to retrograde, when the conditions of life +are very easy. With highly civilised nations continued progress depends in +a subordinate degree on natural selection; for such nations do not supplant +and exterminate one another as do savage tribes. Nevertheless the more +intelligent members within the same community will succeed better in the +long run than the inferior, and leave a more numerous progeny, and this is +a form of natural selection. The more efficient causes of progress seem to +consist of a good education during youth whilst the brain is impressible, +and of a high standard of excellence, inculcated by the ablest and best +men, embodied in the laws, customs and traditions of the nation, and +enforced by public opinion. It should, however, be borne in mind, that the +enforcement of public opinion depends on our appreciation of the +approbation and disapprobation of others; and this appreciation is founded +on our sympathy, which it can hardly be doubted was originally developed +through natural selection as one of the most important elements of the +social instincts. (31. I am much indebted to Mr. John Morley for some +good criticisms on this subject: see, also Broca, 'Les Selections,' 'Revue +d'Anthropologie,' 1872.) + +ON THE EVIDENCE THAT ALL CIVILISED NATIONS WERE ONCE BARBAROUS. + +The present subject has been treated in so full and admirable a manner by +Sir J. Lubbock (32. 'On the Origin of Civilisation,' 'Proceedings of the +Ethnological Society,' Nov. 26, 1867.), Mr. Tylor, Mr. M'Lennan, and +others, that I need here give only the briefest summary of their results. +The arguments recently advanced by the Duke of Argyll (33. 'Primeval Man,' +1869.) and formerly by Archbishop Whately, in favour of the belief that man +came into the world as a civilised being, and that all savages have since +undergone degradation, seem to me weak in comparison with those advanced on +the other side. Many nations, no doubt, have fallen away in civilisation, +and some may have lapsed into utter barbarism, though on this latter head I +have met with no evidence. The Fuegians were probably compelled by other +conquering hordes to settle in their inhospitable country, and they may +have become in consequence somewhat more degraded; but it would be +difficult to prove that they have fallen much below the Botocudos, who +inhabit the finest parts of Brazil. + +The evidence that all civilised nations are the descendants of barbarians, +consists, on the one side, of clear traces of their former low condition in +still-existing customs, beliefs, language, etc.; and on the other side, of +proofs that savages are independently able to raise themselves a few steps +in the scale of civilisation, and have actually thus risen. The evidence +on the first head is extremely curious, but cannot be here given: I refer +to such cases as that of the art of enumeration, which, as Mr. Tylor +clearly shews by reference to the words still used in some places, +originated in counting the fingers, first of one hand and then of the +other, and lastly of the toes. We have traces of this in our own decimal +system, and in the Roman numerals, where, after the V, which is supposed to +be an abbreviated picture of a human hand, we pass on to VI, etc., when the +other hand no doubt was used. So again, "when we speak of three-score and +ten, we are counting by the vigesimal system, each score thus ideally made, +standing for 20--for 'one man' as a Mexican or Carib would put it." (34. +'Royal Institution of Great Britain,' March 15, 1867. Also, 'Researches +into the Early History of Mankind,' 1865.) According to a large and +increasing school of philologists, every language bears the marks of its +slow and gradual evolution. So it is with the art of writing, for letters +are rudiments of pictorial representations. It is hardly possible to read +Mr. M'Lennan's work (35. 'Primitive Marriage,' 1865. See, likewise, an +excellent article, evidently by the same author, in the 'North British +Review,' July 1869. Also, Mr. L.H. Morgan, 'A Conjectural Solution of the +Origin of the Class, System of Relationship,' in 'Proc. American Acad. of +Sciences,' vol. vii. Feb. 1868. Prof. Schaaffhausen ('Anthropolog. +Review,' Oct. 1869, p. 373) remarks on "the vestiges of human sacrifices +found both in Homer and the Old Testament.") and not admit that almost all +civilised nations still retain traces of such rude habits as the forcible +capture of wives. What ancient nation, as the same author asks, can be +named that was originally monogamous? The primitive idea of justice, as +shewn by the law of battle and other customs of which vestiges still +remain, was likewise most rude. Many existing superstitions are the +remnants of former false religious beliefs. The highest form of religion-- +the grand idea of God hating sin and loving righteousness--was unknown +during primeval times. + +Turning to the other kind of evidence: Sir J. Lubbock has shewn that some +savages have recently improved a little in some of their simpler arts. +From the extremely curious account which he gives of the weapons, tools, +and arts, in use amongst savages in various parts of the world, it cannot +be doubted that these have nearly all been independent discoveries, +excepting perhaps the art of making fire. (36. Sir J. Lubbock, +'Prehistoric Times,' 2nd edit. 1869, chaps. xv. and xvi. et passim. See +also the excellent 9th Chapter in Tylor's 'Early History of Mankind,' 2nd +edit., 1870.) The Australian boomerang is a good instance of one such +independent discovery. The Tahitians when first visited had advanced in +many respects beyond the inhabitants of most of the other Polynesian +islands. There are no just grounds for the belief that the high culture of +the native Peruvians and Mexicans was derived from abroad (37. Dr. F. +Müller has made some good remarks to this effect in the 'Reise der Novara: +Anthropolog. Theil,' Abtheil. iii. 1868, s. 127.); many native plants were +there cultivated, and a few native animals domesticated. We should bear in +mind that, judging from the small influence of most missionaries, a +wandering crew from some semi-civilised land, if washed to the shores of +America, would not have produced any marked effect on the natives, unless +they had already become somewhat advanced. Looking to a very remote period +in the history of the world, we find, to use Sir J. Lubbock's well-known +terms, a paleolithic and neolithic period; and no one will pretend that the +art of grinding rough flint tools was a borrowed one. In all parts of +Europe, as far east as Greece, in Palestine, India, Japan, New Zealand, and +Africa, including Egypt, flint tools have been discovered in abundance; and +of their use the existing inhabitants retain no tradition. There is also +indirect evidence of their former use by the Chinese and ancient Jews. +Hence there can hardly be a doubt that the inhabitants of these countries, +which include nearly the whole civilised world, were once in a barbarous +condition. To believe that man was aboriginally civilised and then +suffered utter degradation in so many regions, is to take a pitiably low +view of human nature. It is apparently a truer and more cheerful view that +progress has been much more general than retrogression; that man has risen, +though by slow and interrupted steps, from a lowly condition to the highest +standard as yet attained by him in knowledge, morals and religion. + + +CHAPTER VI. + +ON THE AFFINITIES AND GENEALOGY OF MAN. + +Position of man in the animal series--The natural system genealogical-- +Adaptive characters of slight value--Various small points of resemblance +between man and the Quadrumana--Rank of man in the natural system-- +Birthplace and antiquity of man--Absence of fossil connecting links--Lower +stages in the genealogy of man, as inferred, firstly from his affinities +and secondly from his structure--Early androgynous condition of the +Vertebrata--Conclusion. + +Even if it be granted that the difference between man and his nearest +allies is as great in corporeal structure as some naturalists maintain, and +although we must grant that the difference between them is immense in +mental power, yet the facts given in the earlier chapters appear to +declare, in the plainest manner, that man is descended from some lower +form, notwithstanding that connecting-links have not hitherto been +discovered. + +Man is liable to numerous, slight, and diversified variations, which are +induced by the same general causes, are governed and transmitted in +accordance with the same general laws, as in the lower animals. Man has +multiplied so rapidly, that he has necessarily been exposed to struggle for +existence, and consequently to natural selection. He has given rise to +many races, some of which differ so much from each other, that they have +often been ranked by naturalists as distinct species. His body is +constructed on the same homological plan as that of other mammals. He +passes through the same phases of embryological development. He retains +many rudimentary and useless structures, which no doubt were once +serviceable. Characters occasionally make their re-appearance in him, +which we have reason to believe were possessed by his early progenitors. +If the origin of man had been wholly different from that of all other +animals, these various appearances would be mere empty deceptions; but such +an admission is incredible. These appearances, on the other hand, are +intelligible, at least to a large extent, if man is the co-descendant with +other mammals of some unknown and lower form. + +Some naturalists, from being deeply impressed with the mental and spiritual +powers of man, have divided the whole organic world into three kingdoms, +the Human, the Animal, and the Vegetable, thus giving to man a separate +kingdom. (1. Isidore Geoffroy St.-Hilaire gives a detailed account of the +position assigned to man by various naturalists in their classifications: +'Hist. Nat. Gen.' tom. ii. 1859, pp. 170-189.) Spiritual powers cannot be +compared or classed by the naturalist: but he may endeavour to shew, as I +have done, that the mental faculties of man and the lower animals do not +differ in kind, although immensely in degree. A difference in degree, +however great, does not justify us in placing man in a distinct kingdom, as +will perhaps be best illustrated by comparing the mental powers of two +insects, namely, a coccus or scale-insect and an ant, which undoubtedly +belong to the same class. The difference is here greater than, though of a +somewhat different kind from, that between man and the highest mammal. The +female coccus, whilst young, attaches itself by its proboscis to a plant; +sucks the sap, but never moves again; is fertilised and lays eggs; and this +is its whole history. On the other hand, to describe the habits and mental +powers of worker-ants, would require, as Pierre Huber has shewn, a large +volume; I may, however, briefly specify a few points. Ants certainly +communicate information to each other, and several unite for the same work, +or for games of play. They recognise their fellow-ants after months of +absence, and feel sympathy for each other. They build great edifices, keep +them clean, close the doors in the evening, and post sentries. They make +roads as well as tunnels under rivers, and temporary bridges over them, by +clinging together. They collect food for the community, and when an +object, too large for entrance, is brought to the nest, they enlarge the +door, and afterwards build it up again. They store up seeds, of which they +prevent the germination, and which, if damp, are brought up to the surface +to dry. They keep aphides and other insects as milch-cows. They go out to +battle in regular bands, and freely sacrifice their lives for the common +weal. They emigrate according to a preconcerted plan. They capture +slaves. They move the eggs of their aphides, as well as their own eggs and +cocoons, into warm parts of the nest, in order that they may be quickly +hatched; and endless similar facts could be given. (2. Some of the most +interesting facts ever published on the habits of ants are given by Mr. +Belt, in his 'Naturalist in Nicaragua,' 1874. See also Mr. Moggridge's +admirable work, 'Harvesting Ants,' etc., 1873, also 'L'Instinct chez les +Insectes,' by M. George Pouchet, 'Revue des Deux Mondes,' Feb. 1870, p. +682.) On the whole, the difference in mental power between an ant and a +coccus is immense; yet no one has ever dreamed of placing these insects in +distinct classes, much less in distinct kingdoms. No doubt the difference +is bridged over by other insects; and this is not the case with man and the +higher apes. But we have every reason to believe that the breaks in the +series are simply the results of many forms having become extinct. + +Professor Owen, relying chiefly on the structure of the brain, has divided +the mammalian series into four sub-classes. One of these he devotes to +man; in another he places both the marsupials and the Monotremata; so that +he makes man as distinct from all other mammals as are these two latter +groups conjoined. This view has not been accepted, as far as I am aware, +by any naturalist capable of forming an independent judgment, and therefore +need not here be further considered. + +We can understand why a classification founded on any single character or +organ--even an organ so wonderfully complex and important as the brain--or +on the high development of the mental faculties, is almost sure to prove +unsatisfactory. This principle has indeed been tried with hymenopterous +insects; but when thus classed by their habits or instincts, the +arrangement proved thoroughly artificial. (3. Westwood, 'Modern +Classification of Insects,' vol. ii. 1840, p. 87.) Classifications may, of +course, be based on any character whatever, as on size, colour, or the +element inhabited; but naturalists have long felt a profound conviction +that there is a natural system. This system, it is now generally admitted, +must be, as far as possible, genealogical in arrangement,--that is, the co- +descendants of the same form must be kept together in one group, apart from +the co-descendants of any other form; but if the parent-forms are related, +so will be their descendants, and the two groups together will form a +larger group. The amount of difference between the several groups--that is +the amount of modification which each has undergone--is expressed by such +terms as genera, families, orders, and classes. As we have no record of +the lines of descent, the pedigree can be discovered only by observing the +degrees of resemblance between the beings which are to be classed. For +this object numerous points of resemblance are of much more importance than +the amount of similarity or dissimilarity in a few points. If two +languages were found to resemble each other in a multitude of words and +points of construction, they would be universally recognised as having +sprung from a common source, notwithstanding that they differed greatly in +some few words or points of construction. But with organic beings the +points of resemblance must not consist of adaptations to similar habits of +life: two animals may, for instance, have had their whole frames modified +for living in the water, and yet they will not be brought any nearer to +each other in the natural system. Hence we can see how it is that +resemblances in several unimportant structures, in useless and rudimentary +organs, or not now functionally active, or in an embryological condition, +are by far the most serviceable for classification; for they can hardly be +due to adaptations within a late period; and thus they reveal the old lines +of descent or of true affinity. + +We can further see why a great amount of modification in some one character +ought not to lead us to separate widely any two organisms. A part which +already differs much from the same part in other allied forms has already, +according to the theory of evolution, varied much; consequently it would +(as long as the organism remained exposed to the same exciting conditions) +be liable to further variations of the same kind; and these, if beneficial, +would be preserved, and thus be continually augmented. In many cases the +continued development of a part, for instance, of the beak of a bird, or of +the teeth of a mammal, would not aid the species in gaining its food, or +for any other object; but with man we can see no definite limit to the +continued development of the brain and mental faculties, as far as +advantage is concerned. Therefore in determining the position of man in +the natural or genealogical system, the extreme development of his brain +ought not to outweigh a multitude of resemblances in other less important +or quite unimportant points. + +The greater number of naturalists who have taken into consideration the +whole structure of man, including his mental faculties, have followed +Blumenbach and Cuvier, and have placed man in a separate Order, under the +title of the Bimana, and therefore on an equality with the orders of the +Quadrumana, Carnivora, etc. Recently many of our best naturalists have +recurred to the view first propounded by Linnaeus, so remarkable for his +sagacity, and have placed man in the same Order with the Quadrumana, under +the title of the Primates. The justice of this conclusion will be +admitted: for in the first place, we must bear in mind the comparative +insignificance for classification of the great development of the brain in +man, and that the strongly-marked differences between the skulls of man and +the Quadrumana (lately insisted upon by Bischoff, Aeby, and others) +apparently follow from their differently developed brains. In the second +place, we must remember that nearly all the other and more important +differences between man and the Quadrumana are manifestly adaptive in their +nature, and relate chiefly to the erect position of man; such as the +structure of his hand, foot, and pelvis, the curvature of his spine, and +the position of his head. The family of Seals offers a good illustration +of the small importance of adaptive characters for classification. These +animals differ from all other Carnivora in the form of their bodies and in +the structure of their limbs, far more than does man from the higher apes; +yet in most systems, from that of Cuvier to the most recent one by Mr. +Flower (4. 'Proceedings Zoological Society,' 1863, p. 4.), seals are +ranked as a mere family in the Order of the Carnivora. If man had not been +his own classifier, he would never have thought of founding a separate +order for his own reception. + +It would be beyond my limits, and quite beyond my knowledge, even to name +the innumerable points of structure in which man agrees with the other +Primates. Our great anatomist and philosopher, Prof. Huxley, has fully +discussed this subject (5. 'Evidence as to Man's Place in Nature,' 1863, +p. 70, et passim.), and concludes that man in all parts of his organization +differs less from the higher apes, than these do from the lower members of +the same group. Consequently there "is no justification for placing man in +a distinct order." + +In an early part of this work I brought forward various facts, shewing how +closely man agrees in constitution with the higher mammals; and this +agreement must depend on our close similarity in minute structure and +chemical composition. I gave, as instances, our liability to the same +diseases, and to the attacks of allied parasites; our tastes in common for +the same stimulants, and the similar effects produced by them, as well as +by various drugs, and other such facts. + +As small unimportant points of resemblance between man and the Quadrumana +are not commonly noticed in systematic works, and as, when numerous, they +clearly reveal our relationship, I will specify a few such points. The +relative position of our features is manifestly the same; and the various +emotions are displayed by nearly similar movements of the muscles and skin, +chiefly above the eyebrows and round the mouth. Some few expressions are, +indeed, almost the same, as in the weeping of certain kinds of monkeys and +in the laughing noise made by others, during which the corners of the mouth +are drawn backwards, and the lower eyelids wrinkled. The external ears are +curiously alike. In man the nose is much more prominent than in most +monkeys; but we may trace the commencement of an aquiline curvature in the +nose of the Hoolock Gibbon; and this in the Semnopithecus nasica is carried +to a ridiculous extreme. + +The faces of many monkeys are ornamented with beards, whiskers, or +moustaches. The hair on the head grows to a great length in some species +of Semnopithecus (6. Isidore Geoffroy St.-Hilaire, 'Hist. Nat. Gen.' tom. +ii. 1859, p. 217.); and in the Bonnet monkey (Macacus radiatus) it radiates +from a point on the crown, with a parting down the middle. It is commonly +said that the forehead gives to man his noble and intellectual appearance; +but the thick hair on the head of the Bonnet monkey terminates downwards +abruptly, and is succeeded by hair so short and fine that at a little +distance the forehead, with the exception of the eyebrows, appears quite +naked. It has been erroneously asserted that eyebrows are not present in +any monkey. In the species just named the degree of nakedness of the +forehead differs in different individuals; and Eschricht states (7. 'Über +die Richtung der Haare,' etc., Müller's 'Archiv fur Anat. und Phys.' 1837, +s. 51.) that in our children the limit between the hairy scalp and the +naked forehead is sometimes not well defined; so that here we seem to have +a trifling case of reversion to a progenitor, in whom the forehead had not +as yet become quite naked. + +It is well known that the hair on our arms tends to converge from above and +below to a point at the elbow. This curious arrangement, so unlike that in +most of the lower mammals, is common to the gorilla, chimpanzee, orang, +some species of Hylobates, and even to some few American monkeys. But in +Hylobates agilis the hair on the fore-arm is directed downwards or towards +the wrist in the ordinary manner; and in H. lar it is nearly erect, with +only a very slight forward inclination; so that in this latter species it +is in a transitional state. It can hardly be doubted that with most +mammals the thickness of the hair on the back and its direction, is adapted +to throw off the rain; even the transverse hairs on the fore-legs of a dog +may serve for this end when he is coiled up asleep. Mr. Wallace, who has +carefully studied the habits of the orang, remarks that the convergence of +the hair towards the elbow on the arms of the orang may be explained as +serving to throw off the rain, for this animal during rainy weather sits +with its arms bent, and with the hands clasped round a branch or over its +head. According to Livingstone, the gorilla also "sits in pelting rain +with his hands over his head." (8. Quoted by Reade, 'The African Sketch +Book,' vol i. 1873, p. 152.) If the above explanation is correct, as seems +probable, the direction of the hair on our own arms offers a curious record +of our former state; for no one supposes that it is now of any use in +throwing off the rain; nor, in our present erect condition, is it properly +directed for this purpose. + +It would, however, be rash to trust too much to the principle of adaptation +in regard to the direction of the hair in man or his early progenitors; for +it is impossible to study the figures given by Eschricht of the arrangement +of the hair on the human foetus (this being the same as in the adult) and +not agree with this excellent observer that other and more complex causes +have intervened. The points of convergence seem to stand in some relation +to those points in the embryo which are last closed in during development. +There appears, also, to exist some relation between the arrangement of the +hair on the limbs, and the course of the medullary arteries. (9. On the +hair in Hylobates, see 'Natural History of Mammals,' by C.L. Martin, 1841, +p. 415. Also, Isidore Geoffroy on the American monkeys and other kinds, +'Hist. Nat. Gen.' vol. ii. 1859, pp. 216, 243. Eschricht, ibid. s. 46, 55, +61. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 619. Wallace, +'Contributions to the Theory of Natural Selection,' 1870, p. 344.) + +It must not be supposed that the resemblances between man and certain apes +in the above and in many other points--such as in having a naked forehead, +long tresses on the head, etc.,--are all necessarily the result of unbroken +inheritance from a common progenitor, or of subsequent reversion. Many of +these resemblances are more probably due to analogous variation, which +follows, as I have elsewhere attempted to shew (10. 'Origin of Species,' +5th edit. 1869, p.194. 'The Variation of Animals and Plants under +Domestication,' vol. ii. 1868, p. 348.), from co-descended organisms having +a similar constitution, and having been acted on by like causes inducing +similar modifications. With respect to the similar direction of the hair +on the fore-arms of man and certain monkeys, as this character is common to +almost all the anthropomorphous apes, it may probably be attributed to +inheritance; but this is not certain, as some very distinct American +monkeys are thus characterised. + +Although, as we have now seen, man has no just right to form a separate +Order for his own reception, he may perhaps claim a distinct Sub-order or +Family. Prof. Huxley, in his last work (11. 'An Introduction to the +Classification of Animals,' 1869, p. 99.), divides the primates into three +Sub-orders; namely, the Anthropidae with man alone, the Simiadae including +monkeys of all kinds, and the Lemuridae with the diversified genera of +lemurs. As far as differences in certain important points of structure are +concerned, man may no doubt rightly claim the rank of a Sub-order; and this +rank is too low, if we look chiefly to his mental faculties. Nevertheless, +from a genealogical point of view it appears that this rank is too high, +and that man ought to form merely a Family, or possibly even only a Sub- +family. If we imagine three lines of descent proceeding from a common +stock, it is quite conceivable that two of them might after the lapse of +ages be so slightly changed as still to remain as species of the same +genus, whilst the third line might become so greatly modified as to deserve +to rank as a distinct Sub-family, Family, or even Order. But in this case +it is almost certain that the third line would still retain through +inheritance numerous small points of resemblance with the other two. Here, +then, would occur the difficulty, at present insoluble, how much weight we +ought to assign in our classifications to strongly-marked differences in +some few points,--that is, to the amount of modification undergone; and how +much to close resemblance in numerous unimportant points, as indicating the +lines of descent or genealogy. To attach much weight to the few but strong +differences is the most obvious and perhaps the safest course, though it +appears more correct to pay great attention to the many small resemblances, +as giving a truly natural classification. + +In forming a judgment on this head with reference to man, we must glance at +the classification of the Simiadae. This family is divided by almost all +naturalists into the Catarrhine group, or Old World monkeys, all of which +are characterised (as their name expresses) by the peculiar structure of +their nostrils, and by having four premolars in each jaw; and into the +Platyrrhine group or New World monkeys (including two very distinct sub- +groups), all of which are characterised by differently constructed +nostrils, and by having six premolars in each jaw. Some other small +differences might be mentioned. Now man unquestionably belongs in his +dentition, in the structure of his nostrils, and some other respects, to +the Catarrhine or Old World division; nor does he resemble the Platyrrhines +more closely than the Catarrhines in any characters, excepting in a few of +not much importance and apparently of an adaptive nature. It is therefore +against all probability that some New World species should have formerly +varied and produced a man-like creature, with all the distinctive +characters proper to the Old World division; losing at the same time all +its own distinctive characters. There can, consequently, hardly be a doubt +that man is an off-shoot from the Old World Simian stem; and that under a +genealogical point of view he must be classed with the Catarrhine division. +(12. This is nearly the same classification as that provisionally adopted +by Mr. St. George Mivart, ('Transactions, Philosophical Society," 1867, p. +300), who, after separating the Lemuridae, divides the remainder of the +Primates into the Hominidae, the Simiadae which answer to the Catarrhines, +the Cebidae, and the Hapalidae,--these two latter groups answering to the +Platyrrhines. Mr. Mivart still abides by the same view; see 'Nature,' +1871, p. 481.) + +The anthropomorphous apes, namely the gorilla, chimpanzee, orang, and +hylobates, are by most naturalists separated from the other Old World +monkeys, as a distinct sub-group. I am aware that Gratiolet, relying on +the structure of the brain, does not admit the existence of this sub-group, +and no doubt it is a broken one. Thus the orang, as Mr. St. G. Mivart +remarks, "is one of the most peculiar and aberrant forms to be found in the +Order." (13. 'Transactions, Zoolog. Soc.' vol. vi. 1867, p. 214.) The +remaining non-anthropomorphous Old World monkeys, are again divided by some +naturalists into two or three smaller sub-groups; the genus Semnopithecus, +with its peculiar sacculated stomach, being the type of one sub-group. But +it appears from M. Gaudry's wonderful discoveries in Attica, that during +the Miocene period a form existed there, which connected Semnopithecus and +Macacus; and this probably illustrates the manner in which the other and +higher groups were once blended together. + +If the anthropomorphous apes be admitted to form a natural sub-group, then +as man agrees with them, not only in all those characters which he +possesses in common with the whole Catarrhine group, but in other peculiar +characters, such as the absence of a tail and of callosities, and in +general appearance, we may infer that some ancient member of the +anthropomorphous sub-group gave birth to man. It is not probable that, +through the law of analogous variation, a member of one of the other lower +sub-groups should have given rise to a man-like creature, resembling the +higher anthropomorphous apes in so many respects. No doubt man, in +comparison with most of his allies, has undergone an extraordinary amount +of modification, chiefly in consequence of the great development of his +brain and his erect position; nevertheless, we should bear in mind that he +"is but one of several exceptional forms of Primates." (14. Mr. St. G. +Mivart, 'Transactions of the Philosophical Society,' 1867, p. 410.) + +Every naturalist, who believes in the principle of evolution, will grant +that the two main divisions of the Simiadae, namely the Catarrhine and +Platyrrhine monkeys, with their sub-groups, have all proceeded from some +one extremely ancient progenitor. The early descendants of this +progenitor, before they had diverged to any considerable extent from each +other, would still have formed a single natural group; but some of the +species or incipient genera would have already begun to indicate by their +diverging characters the future distinctive marks of the Catarrhine and +Platyrrhine divisions. Hence the members of this supposed ancient group +would not have been so uniform in their dentition, or in the structure of +their nostrils, as are the existing Catarrhine monkeys in one way and the +Platyrrhines in another way, but would have resembled in this respect the +allied Lemuridae, which differ greatly from each other in the form of their +muzzles (15. Messrs. Murie and Mivart on the Lemuroidea, 'Transactions, +Zoological Society,' vol. vii, 1869, p. 5.), and to an extraordinary degree +in their dentition. + +The Catarrhine and Platyrrhine monkeys agree in a multitude of characters, +as is shewn by their unquestionably belonging to one and the same Order. +The many characters which they possess in common can hardly have been +independently acquired by so many distinct species; so that these +characters must have been inherited. But a naturalist would undoubtedly +have ranked as an ape or a monkey, an ancient form which possessed many +characters common to the Catarrhine and Platyrrhine monkeys, other +characters in an intermediate condition, and some few, perhaps, distinct +from those now found in either group. And as man from a genealogical point +of view belongs to the Catarrhine or Old World stock, we must conclude, +however much the conclusion may revolt our pride, that our early +progenitors would have been properly thus designated. (16. Haeckel has +come to this same conclusion. See 'Über die Entstehung des +Menschengeschlechts,' in Virchow's 'Sammlung. gemein. wissen. Vorträge,' +1868, s. 61. Also his 'Natürliche Schöpfungsgeschicte,' 1868, in which he +gives in detail his views on the genealogy of man.) But we must not fall +into the error of supposing that the early progenitor of the whole Simian +stock, including man, was identical with, or even closely resembled, any +existing ape or monkey. + +ON THE BIRTHPLACE AND ANTIQUITY OF MAN. + +We are naturally led to enquire, where was the birthplace of man at that +stage of descent when our progenitors diverged from the Catarrhine stock? +The fact that they belonged to this stock clearly shews that they inhabited +the Old World; but not Australia nor any oceanic island, as we may infer +from the laws of geographical distribution. In each great region of the +world the living mammals are closely related to the extinct species of the +same region. It is therefore probable that Africa was formerly inhabited +by extinct apes closely allied to the gorilla and chimpanzee; and as these +two species are now man's nearest allies, it is somewhat more probable that +our early progenitors lived on the African continent than elsewhere. But +it is useless to speculate on this subject; for two or three +anthropomorphous apes, one the Dryopithecus (17. Dr. C. Forsyth Major, +'Sur les Singes fossiles trouvés en Italie:' 'Soc. Ital. des Sc. Nat.' tom. +xv. 1872.) of Lartet, nearly as large as a man, and closely allied to +Hylobates, existed in Europe during the Miocene age; and since so remote a +period the earth has certainly undergone many great revolutions, and there +has been ample time for migration on the largest scale. + +At the period and place, whenever and wherever it was, when man first lost +his hairy covering, he probably inhabited a hot country; a circumstance +favourable for the frugiferous diet on which, judging from analogy, he +subsisted. We are far from knowing how long ago it was when man first +diverged from the Catarrhine stock; but it may have occurred at an epoch as +remote as the Eocene period; for that the higher apes had diverged from the +lower apes as early as the Upper Miocene period is shewn by the existence +of the Dryopithecus. We are also quite ignorant at how rapid a rate +organisms, whether high or low in the scale, may be modified under +favourable circumstances; we know, however, that some have retained the +same form during an enormous lapse of time. From what we see going on +under domestication, we learn that some of the co-descendants of the same +species may be not at all, some a little, and some greatly changed, all +within the same period. Thus it may have been with man, who has undergone +a great amount of modification in certain characters in comparison with the +higher apes. + +The great break in the organic chain between man and his nearest allies, +which cannot be bridged over by any extinct or living species, has often +been advanced as a grave objection to the belief that man is descended from +some lower form; but this objection will not appear of much weight to those +who, from general reasons, believe in the general principle of evolution. +Breaks often occur in all parts of the series, some being wide, sharp and +defined, others less so in various degrees; as between the orang and its +nearest allies--between the Tarsius and the other Lemuridae--between the +elephant, and in a more striking manner between the Ornithorhynchus or +Echidna, and all other mammals. But these breaks depend merely on the +number of related forms which have become extinct. At some future period, +not very distant as measured by centuries, the civilised races of man will +almost certainly exterminate, and replace, the savage races throughout the +world. At the same time the anthropomorphous apes, as Professor +Schaaffhausen has remarked (18. 'Anthropological Review,' April 1867, p. +236.), will no doubt be exterminated. The break between man and his +nearest allies will then be wider, for it will intervene between man in a +more civilised state, as we may hope, even than the Caucasian, and some ape +as low as a baboon, instead of as now between the negro or Australian and +the gorilla. + +With respect to the absence of fossil remains, serving to connect man with +his ape-like progenitors, no one will lay much stress on this fact who +reads Sir C. Lyell's discussion (19. 'Elements of Geology,' 1865, pp. 583- +585. 'Antiquity of Man,' 1863, p. 145.), where he shews that in all the +vertebrate classes the discovery of fossil remains has been a very slow and +fortuitous process. Nor should it be forgotten that those regions which +are the most likely to afford remains connecting man with some extinct ape- +like creature, have not as yet been searched by geologists. + +LOWER STAGES IN THE GENEALOGY OF MAN. + +We have seen that man appears to have diverged from the Catarrhine or Old +World division of the Simiadae, after these had diverged from the New World +division. We will now endeavour to follow the remote traces of his +genealogy, trusting principally to the mutual affinities between the +various classes and orders, with some slight reference to the periods, as +far as ascertained, of their successive appearance on the earth. The +Lemuridae stand below and near to the Simiadae, and constitute a very +distinct family of the primates, or, according to Haeckel and others, a +distinct Order. This group is diversified and broken to an extraordinary +degree, and includes many aberrant forms. It has, therefore, probably +suffered much extinction. Most of the remnants survive on islands, such as +Madagascar and the Malayan archipelago, where they have not been exposed to +so severe a competition as they would have been on well-stocked continents. +This group likewise presents many gradations, leading, as Huxley remarks +(20. 'Man's Place in Nature,' p. 105.), "insensibly from the crown and +summit of the animal creation down to creatures from which there is but a +step, as it seems, to the lowest, smallest, and least intelligent of the +placental mammalia." From these various considerations it is probable that +the Simiadae were originally developed from the progenitors of the existing +Lemuridae; and these in their turn from forms standing very low in the +mammalian series. + +The Marsupials stand in many important characters below the placental +mammals. They appeared at an earlier geological period, and their range +was formerly much more extensive than at present. Hence the Placentata are +generally supposed to have been derived from the Implacentata or +Marsupials; not, however, from forms closely resembling the existing +Marsupials, but from their early progenitors. The Monotremata are plainly +allied to the Marsupials, forming a third and still lower division in the +great mammalian series. They are represented at the present day solely by +the Ornithorhynchus and Echidna; and these two forms may be safely +considered as relics of a much larger group, representatives of which have +been preserved in Australia through some favourable concurrence of +circumstances. The Monotremata are eminently interesting, as leading in +several important points of structure towards the class of reptiles. + +In attempting to trace the genealogy of the Mammalia, and therefore of man, +lower down in the series, we become involved in greater and greater +obscurity; but as a most capable judge, Mr. Parker, has remarked, we have +good reason to believe, that no true bird or reptile intervenes in the +direct line of descent. He who wishes to see what ingenuity and knowledge +can effect, may consult Prof. Haeckel's works. (21. Elaborate tables are +given in his 'Generelle Morphologie' (B. ii. s. cliii. and s. 425); and +with more especial reference to man in his 'Natürliche +Schöpfungsgeschichte,' 1868. Prof. Huxley, in reviewing this latter work +('The Academy,' 1869, p. 42) says, that he considers the phylum or lines of +descent of the Vertebrata to be admirably discussed by Haeckel, although he +differs on some points. He expresses, also, his high estimate of the +general tenor and spirit of the whole work.) I will content myself with a +few general remarks. Every evolutionist will admit that the five great +vertebrate classes, namely, mammals, birds, reptiles, amphibians, and +fishes, are descended from some one prototype; for they have much in +common, especially during their embryonic state. As the class of fishes is +the most lowly organised, and appeared before the others, we may conclude +that all the members of the vertebrate kingdom are derived from some +fishlike animal. The belief that animals so distinct as a monkey, an +elephant, a humming-bird, a snake, a frog, and a fish, etc., could all have +sprung from the same parents, will appear monstrous to those who have not +attended to the recent progress of natural history. For this belief +implies the former existence of links binding closely together all these +forms, now so utterly unlike. + +Nevertheless, it is certain that groups of animals have existed, or do now +exist, which serve to connect several of the great vertebrate classes more +or less closely. We have seen that the Ornithorhynchus graduates towards +reptiles; and Prof. Huxley has discovered, and is confirmed by Mr. Cope and +others, that the Dinosaurians are in many important characters intermediate +between certain reptiles and certain birds--the birds referred to being the +ostrich-tribe (itself evidently a widely-diffused remnant of a larger +group) and the Archeopteryx, that strange Secondary bird, with a long +lizard-like tail. Again, according to Prof. Owen (22. 'Palaeontology' +1860, p. 199.), the Ichthyosaurians--great sea-lizards furnished with +paddles--present many affinities with fishes, or rather, according to +Huxley, with amphibians; a class which, including in its highest division +frogs and toads, is plainly allied to the Ganoid fishes. These latter +fishes swarmed during the earlier geological periods, and were constructed +on what is called a generalised type, that is, they presented diversified +affinities with other groups of organisms. The Lepidosiren is also so +closely allied to amphibians and fishes, that naturalists long disputed in +which of these two classes to rank it; it, and also some few Ganoid fishes, +have been preserved from utter extinction by inhabiting rivers, which are +harbours of refuge, and are related to the great waters of the ocean in the +same way that islands are to continents. + +Lastly, one single member of the immense and diversified class of fishes, +namely, the lancelet or amphioxus, is so different from all other fishes, +that Haeckel maintains that it ought to form a distinct class in the +vertebrate kingdom. This fish is remarkable for its negative characters; +it can hardly be said to possess a brain, vertebral column, or heart, etc.; +so that it was classed by the older naturalists amongst the worms. Many +years ago Prof. Goodsir perceived that the lancelet presented some +affinities with the Ascidians, which are invertebrate, hermaphrodite, +marine creatures permanently attached to a support. They hardly appear +like animals, and consist of a simple, tough, leathery sack, with two small +projecting orifices. They belong to the Mulluscoida of Huxley--a lower +division of the great kingdom of the Mollusca; but they have recently been +placed by some naturalists amongst the Vermes or worms. Their larvae +somewhat resemble tadpoles in shape (23. At the Falkland Islands I had the +satisfaction of seeing, in April, 1833, and therefore some years before any +other naturalist, the locomotive larvae of a compound Ascidian, closely +allied to Synoicum, but apparently generically distinct from it. The tail +was about five times as long as the oblong head, and terminated in a very +fine filament. It was, as sketched by me under a simple microscope, +plainly divided by transverse opaque partitions, which I presume represent +the great cells figured by Kovalevsky. At an early stage of development +the tail was closely coiled round the head of the larva.), and have the +power of swimming freely about. Mr. Kovalevsky (24. 'Memoires de l'Acad. +des Sciences de St. Petersbourg,' tom. x. No. 15, 1866.) has lately +observed that the larvae of Ascidians are related to the Vertebrata, in +their manner of development, in the relative position of the nervous +system, and in possessing a structure closely like the chorda dorsalis of +vertebrate animals; and in this he has been since confirmed by Prof. +Kupffer. M. Kovalevsky writes to me from Naples, that he has now carried +these observations yet further, and should his results be well established, +the whole will form a discovery of the very greatest value. Thus, if we +may rely on embryology, ever the safest guide in classification, it seems +that we have at last gained a clue to the source whence the Vertebrata were +derived. (25. But I am bound to add that some competent judges dispute +this conclusion; for instance, M. Giard, in a series of papers in the +'Archives de Zoologie Experimentale,' for 1872. Nevertheless, this +naturalist remarks, p. 281, "L'organisation de la larve ascidienne en +dehors de toute hypothèse et de toute théorie, nous montre comment la +nature peut produire la disposition fondamentale du type vertébré +(l'existence d'une corde dorsale) chez un invertébré par la seule condition +vitale de l'adaptation, et cette simple possibilité du passage supprime +l'abîme entre les deux sous-règnes, encore bien qu'en ignore par où le +passage s'est fait en realité.") We should then be justified in believing +that at an extremely remote period a group of animals existed, resembling +in many respects the larvae of our present Ascidians, which diverged into +two great branches--the one retrograding in development and producing the +present class of Ascidians, the other rising to the crown and summit of the +animal kingdom by giving birth to the Vertebrata. + +We have thus far endeavoured rudely to trace the genealogy of the +Vertebrata by the aid of their mutual affinities. We will now look to man +as he exists; and we shall, I think, be able partially to restore the +structure of our early progenitors, during successive periods, but not in +due order of time. This, can be effected by means of the rudiments which +man still retains, by the characters which occasionally make their +appearance in him through reversion, and by the aid of the principles of +morphology and embryology. The various facts, to which I shall here +allude, have been given in the previous chapters. + +The early progenitors of man must have been once covered with hair, both +sexes having beards; their ears were probably pointed, and capable of +movement; and their bodies were provided with a tail, having the proper +muscles. Their limbs and bodies were also acted on by many muscles which +now only occasionally reappear, but are normally present in the Quadrumana. +At this or some earlier period, the great artery and nerve of the humerus +ran through a supra-condyloid foramen. The intestine gave forth a much +larger diverticulum or caecum than that now existing. The foot was then +prehensile, judging from the condition of the great toe in the foetus; and +our progenitors, no doubt, were arboreal in their habits, and frequented +some warm, forest-clad land. The males had great canine teeth, which +served them as formidable weapons. At a much earlier period the uterus was +double; the excreta were voided through a cloaca; and the eye was protected +by a third eyelid or nictitating membrane. At a still earlier period the +progenitors of man must have been aquatic in their habits; for morphology +plainly tells us that our lungs consist of a modified swim-bladder, which +once served as a float. The clefts on the neck in the embryo of man shew +where the branchiae once existed. In the lunar or weekly recurrent periods +of some of our functions we apparently still retain traces of our +primordial birthplace, a shore washed by the tides. At about this same +early period the true kidneys were replaced by the corpora wolffiana. The +heart existed as a simple pulsating vessel; and the chorda dorsalis took +the place of a vertebral column. These early ancestors of man, thus seen +in the dim recesses of time, must have been as simply, or even still more +simply organised than the lancelet or amphioxus. + +There is one other point deserving a fuller notice. It has long been known +that in the vertebrate kingdom one sex bears rudiments of various accessory +parts, appertaining to the reproductive system, which properly belong to +the opposite sex; and it has now been ascertained that at a very early +embryonic period both sexes possess true male and female glands. Hence +some remote progenitor of the whole vertebrate kingdom appears to have been +hermaphrodite or androgynous. (26. This is the conclusion of Prof. +Gegenbaur, one of the highest authorities in comparative anatomy: see +'Grundzüge der vergleich. Anat.' 1870, s. 876. The result has been arrived +at chiefly from the study of the Amphibia; but it appears from the +researches of Waldeyer (as quoted in 'Journal of Anat. and Phys.' 1869, p. +161), that the sexual organs of even "the higher vertebrata are, in their +early condition, hermaphrodite." Similar views have long been held by some +authors, though until recently without a firm basis.) But here we +encounter a singular difficulty. In the mammalian class the males possess +rudiments of a uterus with the adjacent passage, in their vesiculae +prostaticae; they bear also rudiments of mammae, and some male Marsupials +have traces of a marsupial sack. (27. The male Thylacinus offers the best +instance. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 771.) Other +analogous facts could be added. Are we, then, to suppose that some +extremely ancient mammal continued androgynous, after it had acquired the +chief distinctions of its class, and therefore after it had diverged from +the lower classes of the vertebrate kingdom? This seems very improbable, +for we have to look to fishes, the lowest of all the classes, to find any +still existent androgynous forms. (28. Hermaphroditism has been observed +in several species of Serranus, as well as in some other fishes, where it +is either normal and symmetrical, or abnormal and unilateral. Dr. +Zouteveen has given me references on this subject, more especially to a +paper by Prof. Halbertsma, in the 'Transact. of the Dutch Acad. of +Sciences,' vol. xvi. Dr. Gunther doubts the fact, but it has now been +recorded by too many good observers to be any longer disputed. Dr. M. +Lessona writes to me, that he has verified the observations made by +Cavolini on Serranus. Prof. Ercolani has recently shewn ('Accad. delle +Scienze,' Bologna, Dec. 28, 1871) that eels are androgynous.) That various +accessory parts, proper to each sex, are found in a rudimentary condition +in the opposite sex, may be explained by such organs having been gradually +acquired by the one sex, and then transmitted in a more or less imperfect +state to the other. When we treat of sexual selection, we shall meet with +innumerable instances of this form of transmission,--as in the case of the +spurs, plumes, and brilliant colours, acquired for battle or ornament by +male birds, and inherited by the females in an imperfect or rudimentary +condition. + +The possession by male mammals of functionally imperfect mammary organs is, +in some respects, especially curious. The Monotremata have the proper +milk-secreting glands with orifices, but no nipples; and as these animals +stand at the very base of the mammalian series, it is probable that the +progenitors of the class also had milk-secreting glands, but no nipples. +This conclusion is supported by what is known of their manner of +development; for Professor Turner informs me, on the authority of Kolliker +and Langer, that in the embryo the mammary glands can be distinctly traced +before the nipples are in the least visible; and the development of +successive parts in the individual generally represents and accords with +the development of successive beings in the same line of descent. The +Marsupials differ from the Monotremata by possessing nipples; so that +probably these organs were first acquired by the Marsupials, after they had +diverged from, and risen above, the Monotremata, and were then transmitted +to the placental mammals. (29. Prof. Gegenbaur has shewn ('Jenäische +Zeitschrift,' Bd. vii. p. 212) that two distinct types of nipples prevail +throughout the several mammalian orders, but that it is quite intelligible +how both could have been derived from the nipples of the Marsupials, and +the latter from those of the Monotremata. See, also, a memoir by Dr. Max +Huss, on the mammary glands, ibid. B. viii. p. 176.) No one will suppose +that the marsupials still remained androgynous, after they had +approximately acquired their present structure. How then are we to account +for male mammals possessing mammae? It is possible that they were first +developed in the females and then transferred to the males, but from what +follows this is hardly probable. + +It may be suggested, as another view, that long after the progenitors of +the whole mammalian class had ceased to be androgynous, both sexes yielded +milk, and thus nourished their young; and in the case of the Marsupials, +that both sexes carried their young in marsupial sacks. This will not +appear altogether improbable, if we reflect that the males of existing +syngnathous fishes receive the eggs of the females in their abdominal +pouches, hatch them, and afterwards, as some believe, nourish the young +(30. Mr. Lockwood believes (as quoted in 'Quart. Journal of Science,' +April 1868, p. 269), from what he has observed of the development of +Hippocampus, that the walls of the abdominal pouch of the male in some way +afford nourishment. On male fishes hatching the ova in their mouths, see a +very interesting paper by Prof. Wyman, in 'Proc. Boston Soc. of Nat. Hist.' +Sept. 15, 1857; also Prof. Turner, in 'Journal of Anatomy and Physiology,' +Nov. 1, 1866, p. 78. Dr. Gunther has likewise described similar cases.);-- +that certain other male fishes hatch the eggs within their mouths or +branchial cavities;--that certain male toads take the chaplets of eggs from +the females, and wind them round their own thighs, keeping them there until +the tadpoles are born;--that certain male birds undertake the whole duty of +incubation, and that male pigeons, as well as the females, feed their +nestlings with a secretion from their crops. But the above suggestion +first occurred to me from mammary glands of male mammals being so much more +perfectly developed than the rudiments of the other accessory reproductive +parts, which are found in the one sex though proper to the other. The +mammary glands and nipples, as they exist in male mammals, can indeed +hardly be called rudimentary; they are merely not fully developed, and not +functionally active. They are sympathetically affected under the influence +of certain diseases, like the same organs in the female. They often +secrete a few drops of milk at birth and at puberty: this latter fact +occurred in the curious case, before referred to, where a young man +possessed two pairs of mammae. In man and some other male mammals these +organs have been known occasionally to become so well developed during +maturity as to yield a fair supply of milk. Now if we suppose that during +a former prolonged period male mammals aided the females in nursing their +offspring (31. Mlle. C. Royer has suggested a similar view in her 'Origine +de l'homme,' etc., 1870.), and that afterwards from some cause (as from the +production of a smaller number of young) the males ceased to give this aid, +disuse of the organs during maturity would lead to their becoming inactive; +and from two well-known principles of inheritance, this state of inactivity +would probably be transmitted to the males at the corresponding age of +maturity. But at an earlier age these organs would be left unaffected, so +that they would be almost equally well developed in the young of both +sexes. + +CONCLUSION. + +Von Baer has defined advancement or progress in the organic scale better +than any one else, as resting on the amount of differentiation and +specialisation of the several parts of a being,--when arrived at maturity, +as I should be inclined to add. Now as organisms have become slowly +adapted to diversified lines of life by means of natural selection, their +parts will have become more and more differentiated and specialised for +various functions from the advantage gained by the division of +physiological labour. The same part appears often to have been modified +first for one purpose, and then long afterwards for some other and quite +distinct purpose; and thus all the parts are rendered more and more +complex. But each organism still retains the general type of structure of +the progenitor from which it was aboriginally derived. In accordance with +this view it seems, if we turn to geological evidence, that organisation on +the whole has advanced throughout the world by slow and interrupted steps. +In the great kingdom of the Vertebrata it has culminated in man. It must +not, however, be supposed that groups of organic beings are always +supplanted, and disappear as soon as they have given birth to other and +more perfect groups. The latter, though victorious over their +predecessors, may not have become better adapted for all places in the +economy of nature. Some old forms appear to have survived from inhabiting +protected sites, where they have not been exposed to very severe +competition; and these often aid us in constructing our genealogies, by +giving us a fair idea of former and lost populations. But we must not fall +into the error of looking at the existing members of any lowly-organised +group as perfect representatives of their ancient predecessors. + +The most ancient progenitors in the kingdom of the Vertebrata, at which we +are able to obtain an obscure glance, apparently consisted of a group of +marine animals (32. The inhabitants of the seashore must be greatly +affected by the tides; animals living either about the MEAN high-water +mark, or about the MEAN low-water mark, pass through a complete cycle of +tidal changes in a fortnight. Consequently, their food supply will undergo +marked changes week by week. The vital functions of such animals, living +under these conditions for many generations, can hardly fail to run their +course in regular weekly periods. Now it is a mysterious fact that in the +higher and now terrestrial Vertebrata, as well as in other classes, many +normal and abnormal processes have one or more whole weeks as their +periods; this would be rendered intelligible if the Vertebrata are +descended from an animal allied to the existing tidal Ascidians. Many +instances of such periodic processes might be given, as the gestation of +mammals, the duration of fevers, etc. The hatching of eggs affords also a +good example, for, according to Mr. Bartlett ('Land and Water,' Jan. 7, +1871), the eggs of the pigeon are hatched in two weeks; those of the fowl +in three; those of the duck in four; those of the goose in five; and those +of the ostrich in seven weeks. As far as we can judge, a recurrent period, +if approximately of the right duration for any process or function, would +not, when once gained, be liable to change; consequently it might be thus +transmitted through almost any number of generations. But if the function +changed, the period would have to change, and would be apt to change almost +abruptly by a whole week. This conclusion, if sound, is highly remarkable; +for the period of gestation in each mammal, and the hatching of each bird's +eggs, and many other vital processes, thus betray to us the primordial +birthplace of these animals.), resembling the larvae of existing Ascidians. +These animals probably gave rise to a group of fishes, as lowly organised +as the lancelet; and from these the Ganoids, and other fishes like the +Lepidosiren, must have been developed. From such fish a very small advance +would carry us on to the Amphibians. We have seen that birds and reptiles +were once intimately connected together; and the Monotremata now connect +mammals with reptiles in a slight degree. But no one can at present say by +what line of descent the three higher and related classes, namely, mammals, +birds, and reptiles, were derived from the two lower vertebrate classes, +namely, amphibians and fishes. In the class of mammals the steps are not +difficult to conceive which led from the ancient Monotremata to the ancient +Marsupials; and from these to the early progenitors of the placental +mammals. We may thus ascend to the Lemuridae; and the interval is not very +wide from these to the Simiadae. The Simiadae then branched off into two +great stems, the New World and Old World monkeys; and from the latter, at a +remote period, Man, the wonder and glory of the Universe, proceeded. + +Thus we have given to man a pedigree of prodigious length, but not, it may +be said, of noble quality. The world, it has often been remarked, appears +as if it had long been preparing for the advent of man: and this, in one +sense is strictly true, for he owes his birth to a long line of +progenitors. If any single link in this chain had never existed, man would +not have been exactly what he now is. Unless we wilfully close our eyes, +we may, with our present knowledge, approximately recognise our parentage; +nor need we feel ashamed of it. The most humble organism is something much +higher than the inorganic dust under our feet; and no one with an unbiassed +mind can study any living creature, however humble, without being struck +with enthusiasm at its marvellous structure and properties. + + +CHAPTER VII. + +ON THE RACES OF MAN. + +The nature and value of specific characters--Application to the races of +man--Arguments in favour of, and opposed to, ranking the so-called races of +man as district species--Sub-species--Monogenists and polygenists-- +Convergence of character--Numerous points of resemblance in body and mind +between the most distinct races of man--The state of man when he first +spread over the earth--Each race not descended from a single pair--The +extinction of races--The formation of races--The effects of crossing-- +Slight influence of the direct action of the conditions of life--Slight or +no influence of natural selection--Sexual selection. + +It is not my intention here to describe the several so-called races of men; +but I am about to enquire what is the value of the differences between them +under a classificatory point of view, and how they have originated. In +determining whether two or more allied forms ought to be ranked as species +or varieties, naturalists are practically guided by the following +considerations; namely, the amount of difference between them, and whether +such differences relate to few or many points of structure, and whether +they are of physiological importance; but more especially whether they are +constant. Constancy of character is what is chiefly valued and sought for +by naturalists. Whenever it can be shewn, or rendered probable, that the +forms in question have remained distinct for a long period, this becomes an +argument of much weight in favour of treating them as species. Even a +slight degree of sterility between any two forms when first crossed, or in +their offspring, is generally considered as a decisive test of their +specific distinctness; and their continued persistence without blending +within the same area, is usually accepted as sufficient evidence, either of +some degree of mutual sterility, or in the case of animals of some mutual +repugnance to pairing. + +Independently of fusion from intercrossing, the complete absence, in a +well-investigated region, of varieties linking together any two closely- +allied forms, is probably the most important of all the criterions of their +specific distinctness; and this is a somewhat different consideration from +mere constancy of character, for two forms may be highly variable and yet +not yield intermediate varieties. Geographical distribution is often +brought into play unconsciously and sometimes consciously; so that forms +living in two widely separated areas, in which most of the other +inhabitants are specifically distinct, are themselves usually looked at as +distinct; but in truth this affords no aid in distinguishing geographical +races from so-called good or true species. + +Now let us apply these generally-admitted principles to the races of man, +viewing him in the same spirit as a naturalist would any other animal. In +regard to the amount of difference between the races, we must make some +allowance for our nice powers of discrimination gained by the long habit of +observing ourselves. In India, as Elphinstone remarks, although a newly- +arrived European cannot at first distinguish the various native races, yet +they soon appear to him extremely dissimilar (1. 'History of India,' 1841, +vol. i. p. 323. Father Ripa makes exactly the same remark with respect to +the Chinese.); and the Hindoo cannot at first perceive any difference +between the several European nations. Even the most distinct races of man +are much more like each other in form than would at first be supposed; +certain negro tribes must be excepted, whilst others, as Dr. Rohlfs writes +to me, and as I have myself seen, have Caucasian features. This general +similarity is well shewn by the French photographs in the Collection +Anthropologique du Museum de Paris of the men belonging to various races, +the greater number of which might pass for Europeans, as many persons to +whom I have shewn them have remarked. Nevertheless, these men, if seen +alive, would undoubtedly appear very distinct, so that we are clearly much +influenced in our judgment by the mere colour of the skin and hair, by +slight differences in the features, and by expression. + +There is, however, no doubt that the various races, when carefully compared +and measured, differ much from each other,--as in the texture of the hair, +the relative proportions of all parts of the body (2. A vast number of +measurements of Whites, Blacks, and Indians, are given in the +'Investigations in the Military and Anthropolog. Statistics of American +Soldiers,' by B.A. Gould, 1869, pp. 298-358; 'On the capacity of the +lungs,' p. 471. See also the numerous and valuable tables, by Dr. +Weisbach, from the observations of Dr. Scherzer and Dr. Schwarz, in the +'Reise der Novara: Anthropolog. Theil,' 1867.), the capacity of the lungs, +the form and capacity of the skull, and even in the convolutions of the +brain. (3. See, for instance, Mr. Marshall's account of the brain of a +Bushwoman, in 'Philosophical Transactions,' 1864, p. 519.) But it would be +an endless task to specify the numerous points of difference. The races +differ also in constitution, in acclimatisation and in liability to certain +diseases. Their mental characteristics are likewise very distinct; chiefly +as it would appear in their emotional, but partly in their intellectual +faculties. Every one who has had the opportunity of comparison, must have +been struck with the contrast between the taciturn, even morose, aborigines +of S. America and the light-hearted, talkative negroes. There is a nearly +similar contrast between the Malays and the Papuans (4. Wallace, 'The +Malay Archipelago,' vol. ii. 1869, p. 178.), who live under the same +physical conditions, and are separated from each other only by a narrow +space of sea. + +We will first consider the arguments which may be advanced in favour of +classing the races of man as distinct species, and then the arguments on +the other side. If a naturalist, who had never before seen a Negro, +Hottentot, Australian, or Mongolian, were to compare them, he would at once +perceive that they differed in a multitude of characters, some of slight +and some of considerable importance. On enquiry he would find that they +were adapted to live under widely different climates, and that they +differed somewhat in bodily constitution and mental disposition. If he +were then told that hundreds of similar specimens could be brought from the +same countries, he would assuredly declare that they were as good species +as many to which he had been in the habit of affixing specific names. This +conclusion would be greatly strengthened as soon as he had ascertained that +these forms had all retained the same character for many centuries; and +that negroes, apparently identical with existing negroes, had lived at +least 4000 years ago. (5. With respect to the figures in the famous +Egyptian caves of Abou-Simbel, M. Pouchet says ('The Plurality of the Human +Races,' Eng. translat., 1864, p. 50), that he was far from finding +recognisable representations of the dozen or more nations which some +authors believe that they can recognise. Even some of the most strongly- +marked races cannot be identified with that degree of unanimity which might +have been expected from what has been written on the subject. Thus Messrs. +Nott and Gliddon ('Types of Mankind,' p. 148), state that Rameses II., or +the Great, has features superbly European; whereas Knox, another firm +believer in the specific distinctness of the races of man ('Races of Man,' +1850, p. 201), speaking of young Memnon (the same as Rameses II., as I am +informed by Mr. Birch), insists in the strongest manner that he is +identical in character with the Jews of Antwerp. Again, when I looked at +the statue of Amunoph III., I agreed with two officers of the +establishment, both competent judges, that he had a strongly-marked negro +type of features; but Messrs. Nott and Gliddon (ibid. p. 146, fig. 53), +describe him as a hybrid, but not of "negro intermixture.") He would also +hear, on the authority of an excellent observer, Dr. Lund (6. As quoted by +Nott and Gliddon, 'Types of Mankind,' 1854, p. 439. They give also +corroborative evidence; but C. Vogt thinks that the subject requires +further investigation.), that the human skulls found in the caves of +Brazil, entombed with many extinct mammals, belonged to the same type as +that now prevailing throughout the American Continent. + +Our naturalist would then perhaps turn to geographical distribution, and he +would probably declare that those forms must be distinct species, which +differ not only in appearance, but are fitted for hot, as well as damp or +dry countries, and for the Artic regions. He might appeal to the fact that +no species in the group next to man--namely, the Quadrumana, can resist a +low temperature, or any considerable change of climate; and that the +species which come nearest to man have never been reared to maturity, even +under the temperate climate of Europe. He would be deeply impressed with +the fact, first noticed by Agassiz (7. 'Diversity of Origin of the Human +Races,' in the 'Christian Examiner,' July 1850.), that the different races +of man are distributed over the world in the same zoological provinces, as +those inhabited by undoubtedly distinct species and genera of mammals. +This is manifestly the case with the Australian, Mongolian, and Negro races +of man; in a less well-marked manner with the Hottentots; but plainly with +the Papuans and Malays, who are separated, as Mr. Wallace has shewn, by +nearly the same line which divides the great Malayan and Australian +zoological provinces. The Aborigines of America range throughout the +Continent; and this at first appears opposed to the above rule, for most of +the productions of the Southern and Northern halves differ widely: yet +some few living forms, as the opossum, range from the one into the other, +as did formerly some of the gigantic Edentata. The Esquimaux, like other +Arctic animals, extend round the whole polar regions. It should be +observed that the amount of difference between the mammals of the several +zoological provinces does not correspond with the degree of separation +between the latter; so that it can hardly be considered as an anomaly that +the Negro differs more, and the American much less from the other races of +man, than do the mammals of the African and American continents from the +mammals of the other provinces. Man, it may be added, does not appear to +have aboriginally inhabited any oceanic island; and in this respect, he +resembles the other members of his class. + +In determining whether the supposed varieties of the same kind of domestic +animal should be ranked as such, or as specifically distinct, that is, +whether any of them are descended from distinct wild species, every +naturalist would lay much stress on the fact of their external parasites +being specifically distinct. All the more stress would be laid on this +fact, as it would be an exceptional one; for I am informed by Mr. Denny +that the most different kinds of dogs, fowls, and pigeons, in England, are +infested by the same species of Pediculi or lice. Now Mr. A. Murray has +carefully examined the Pediculi collected in different countries from the +different races of man (8. 'Transactions of the Royal Society of +Edinburgh,' vol. xxii, 1861, p. 567.); and he finds that they differ, not +only in colour, but in the structure of their claws and limbs. In every +case in which many specimens were obtained the differences were constant. +The surgeon of a whaling ship in the Pacific assured me that when the +Pediculi, with which some Sandwich Islanders on board swarmed, strayed on +to the bodies of the English sailors, they died in the course of three or +four days. These Pediculi were darker coloured, and appeared different +from those proper to the natives of Chiloe in South America, of which he +gave me specimens. These, again, appeared larger and much softer than +European lice. Mr. Murray procured four kinds from Africa, namely, from +the Negroes of the Eastern and Western coasts, from the Hottentots and +Kaffirs; two kinds from the natives of Australia; two from North and two +from South America. In these latter cases it may be presumed that the +Pediculi came from natives inhabiting different districts. With insects +slight structural differences, if constant, are generally esteemed of +specific value: and the fact of the races of man being infested by +parasites, which appear to be specifically distinct, might fairly be urged +as an argument that the races themselves ought to be classed as distinct +species. + +Our supposed naturalist having proceeded thus far in his investigation, +would next enquire whether the races of men, when crossed, were in any +degree sterile. He might consult the work (9. 'On the Phenomena of +Hybridity in the Genus Homo,' Eng. translat., 1864.) of Professor Broca, a +cautious and philosophical observer, and in this he would find good +evidence that some races were quite fertile together, but evidence of an +opposite nature in regard to other races. Thus it has been asserted that +the native women of Australia and Tasmania rarely produce children to +European men; the evidence, however, on this head has now been shewn to be +almost valueless. The half-castes are killed by the pure blacks: and an +account has lately been published of eleven half-caste youths murdered and +burnt at the same time, whose remains were found by the police. (10. See +the interesting letter by Mr. T.A. Murray, in the 'Anthropological Review,' +April 1868, p. liii. In this letter Count Strzelecki's statement that +Australian women who have borne children to a white man, are afterwards +sterile with their own race, is disproved. M. A. de Quatrefages has also +collected (Revue des Cours Scientifiques, March, 1869, p. 239), much +evidence that Australians and Europeans are not sterile when crossed.) +Again, it has often been said that when mulattoes intermarry, they produce +few children; on the other hand, Dr. Bachman, of Charleston (11. 'An +Examination of Prof. Agassiz's Sketch of the Nat. Provinces of the Animal +World,' Charleston, 1855, p. 44.), positively asserts that he has known +mulatto families which have intermarried for several generations, and have +continued on an average as fertile as either pure whites or pure blacks. +Enquiries formerly made by Sir C. Lyell on this subject led him, as he +informs me, to the same conclusion. (12. Dr. Rohlfs writes to me that he +found the mixed races in the Great Sahara, derived from Arabs, Berbers, and +Negroes of three tribes, extraordinarily fertile. On the other hand, Mr. +Winwood Reade informs me that the Negroes on the Gold Coast, though +admiring white men and mulattoes, have a maxim that mulattoes should not +intermarry, as the children are few and sickly. This belief, as Mr. Reade +remarks, deserves attention, as white men have visited and resided on the +Gold Coast for four hundred years, so that the natives have had ample time +to gain knowledge through experience.) In the United States the census for +the year 1854 included, according to Dr. Bachman, 405,751 mulattoes; and +this number, considering all the circumstances of the case, seems small; +but it may partly be accounted for by the degraded and anomalous position +of the class, and by the profligacy of the women. A certain amount of +absorption of mulattoes into negroes must always be in progress; and this +would lead to an apparent diminution of the former. The inferior vitality +of mulattoes is spoken of in a trustworthy work (13. 'Military and +Anthropological Statistics of American Soldiers,' by B.A. Gould, 1869, p. +319.) as a well-known phenomenon; and this, although a different +consideration from their lessened fertility, may perhaps be advanced as a +proof of the specific distinctness of the parent races. No doubt both +animal and vegetable hybrids, when produced from extremely distinct +species, are liable to premature death; but the parents of mulattoes cannot +be put under the category of extremely distinct species. The common Mule, +so notorious for long life and vigour, and yet so sterile, shews how little +necessary connection there is in hybrids between lessened fertility and +vitality; other analogous cases could be cited. + +Even if it should hereafter be proved that all the races of men were +perfectly fertile together, he who was inclined from other reasons to rank +them as distinct species, might with justice argue that fertility and +sterility are not safe criterions of specific distinctness. We know that +these qualities are easily affected by changed conditions of life, or by +close inter-breeding, and that they are governed by highly complex laws, +for instance, that of the unequal fertility of converse crosses between the +same two species. With forms which must be ranked as undoubted species, a +perfect series exists from those which are absolutely sterile when crossed, +to those which are almost or completely fertile. The degrees of sterility +do not coincide strictly with the degrees of difference between the parents +in external structure or habits of life. Man in many respects may be +compared with those animals which have long been domesticated, and a large +body of evidence can be advanced in favour of the Pallasian doctrine (14. +The 'Variation of Animals and Plants under Domestication,' vol. ii. p. 109. +I may here remind the reader that the sterility of species when crossed is +not a specially-acquired quality, but, like the incapacity of certain trees +to be grafted together, is incidental on other acquired differences. The +nature of these differences is unknown, but they relate more especially to +the reproductive system, and much less so to external structure or to +ordinary differences in constitution. One important element in the +sterility of crossed species apparently lies in one or both having been +long habituated to fixed conditions; for we know that changed conditions +have a special influence on the reproductive system, and we have good +reason to believe (as before remarked) that the fluctuating conditions of +domestication tend to eliminate that sterility which is so general with +species, in a natural state, when crossed. It has elsewhere been shewn by +me (ibid. vol. ii. p. 185, and 'Origin of Species,' 5th edit. p. 317), that +the sterility of crossed species has not been acquired through natural +selection: we can see that when two forms have already been rendered very +sterile, it is scarcely possible that their sterility should be augmented +by the preservation or survival of the more and more sterile individuals; +for, as the sterility increases, fewer and fewer offspring will be produced +from which to breed, and at last only single individuals will be produced +at the rarest intervals. But there is even a higher grade of sterility +than this. Both Gartner and Kolreuter have proved that in genera of +plants, including many species, a series can be formed from species which, +when crossed, yield fewer and fewer seeds, to species which never produce a +single seed, but yet are affected by the pollen of the other species, as +shewn by the swelling of the germen. It is here manifestly impossible to +select the more sterile individuals, which have already ceased to yield +seeds; so that the acme of sterility, when the germen alone is affected, +cannot have been gained through selection. This acme, and no doubt the +other grades of sterility, are the incidental results of certain unknown +differences in the constitution of the reproductive system of the species +which are crossed.), that domestication tends to eliminate the sterility +which is so general a result of the crossing of species in a state of +nature. From these several considerations, it may be justly urged that the +perfect fertility of the intercrossed races of man, if established, would +not absolutely preclude us from ranking them as distinct species. + +Independently of fertility, the characters presented by the offspring from +a cross have been thought to indicate whether or not the parent-forms ought +to be ranked as species or varieties; but after carefully studying the +evidence, I have come to the conclusion that no general rules of this kind +can be trusted. The ordinary result of a cross is the production of a +blended or intermediate form; but in certain cases some of the offspring +take closely after one parent-form, and some after the other. This is +especially apt to occur when the parents differ in characters which first +appeared as sudden variations or monstrosities. (15. 'The Variation of +Animals,' etc., vol. ii. p. 92.) I refer to this point, because Dr. Rohlfs +informs me that he has frequently seen in Africa the offspring of negroes +crossed with members of other races, either completely black or completely +white, or rarely piebald. On the other hand, it is notorious that in +America mulattoes commonly present an intermediate appearance. + +We have now seen that a naturalist might feel himself fully justified in +ranking the races of man as distinct species; for he has found that they +are distinguished by many differences in structure and constitution, some +being of importance. These differences have, also, remained nearly +constant for very long periods of time. Our naturalist will have been in +some degree influenced by the enormous range of man, which is a great +anomaly in the class of mammals, if mankind be viewed as a single species. +He will have been struck with the distribution of the several so-called +races, which accords with that of other undoubtedly distinct species of +mammals. Finally, he might urge that the mutual fertility of all the races +has not as yet been fully proved, and even if proved would not be an +absolute proof of their specific identity. + +On the other side of the question, if our supposed naturalist were to +enquire whether the forms of man keep distinct like ordinary species, when +mingled together in large numbers in the same country, he would immediately +discover that this was by no means the case. In Brazil he would behold an +immense mongrel population of Negroes and Portuguese; in Chiloe, and other +parts of South America, he would behold the whole population consisting of +Indians and Spaniards blended in various degrees. (16. M. de Quatrefages +has given ('Anthropological Review,' Jan. 1869, p. 22), an interesting +account of the success and energy of the Paulistas in Brazil, who are a +much crossed race of Portuguese and Indians, with a mixture of the blood of +other races.) In many parts of the same continent he would meet with the +most complex crosses between Negroes, Indians, and Europeans; and judging +from the vegetable kingdom, such triple crosses afford the severest test of +the mutual fertility of the parent forms. In one island of the Pacific he +would find a small population of mingled Polynesian and English blood; and +in the Fiji Archipelago a population of Polynesian and Negritos crossed in +all degrees. Many analogous cases could be added; for instance, in Africa. +Hence the races of man are not sufficiently distinct to inhabit the same +country without fusion; and the absence of fusion affords the usual and +best test of specific distinctness. + +Our naturalist would likewise be much disturbed as soon as he perceived +that the distinctive characters of all the races were highly variable. +This fact strikes every one on first beholding the negro slaves in Brazil, +who have been imported from all parts of Africa. The same remark holds +good with the Polynesians, and with many other races. It may be doubted +whether any character can be named which is distinctive of a race and is +constant. Savages, even within the limits of the same tribe, are not +nearly so uniform in character, as has been often asserted. Hottentot +women offer certain peculiarities, more strongly marked than those +occurring in any other race, but these are known not to be of constant +occurrence. In the several American tribes, colour and hairiness differ +considerably; as does colour to a certain degree, and the shape of the +features greatly, in the Negroes of Africa. The shape of the skull varies +much in some races (17. For instance, with the aborigines of America and +Australia, Prof. Huxley says ('Transact. Internat. Congress of Prehist. +Arch.' 1868, p. 105), that the skulls of many South Germans and Swiss are +"as short and as broad as those of the Tartars," etc.); and so it is with +every other character. Now all naturalists have learnt by dearly bought +experience, how rash it is to attempt to define species by the aid of +inconstant characters. + +But the most weighty of all the arguments against treating the races of man +as distinct species, is that they graduate into each other, independently +in many cases, as far as we can judge, of their having intercrossed. Man +has been studied more carefully than any other animal, and yet there is the +greatest possible diversity amongst capable judges whether he should be +classed as a single species or race, or as two (Virey), as three +(Jacquinot), as four (Kant), five (Blumenbach), six (Buffon), seven +(Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory St. Vincent), +sixteen (Desmoulins), twenty-two (Morton), sixty (Crawfurd), or as sixty- +three, according to Burke. (18. See a good discussion on this subject in +Waitz, 'Introduction to Anthropology,' Eng. translat., 1863, pp. 198-208, +227. I have taken some of the above statements from H. Tuttle's 'Origin +and Antiquity of Physical Man,' Boston, 1866, p. 35.) This diversity of +judgment does not prove that the races ought not to be ranked as species, +but it shews that they graduate into each other, and that it is hardly +possible to discover clear distinctive characters between them. + +Every naturalist who has had the misfortune to undertake the description of +a group of highly varying organisms, has encountered cases (I speak after +experience) precisely like that of man; and if of a cautious disposition, +he will end by uniting all the forms which graduate into each other, under +a single species; for he will say to himself that he has no right to give +names to objects which he cannot define. Cases of this kind occur in the +Order which includes man, namely in certain genera of monkeys; whilst in +other genera, as in Cercopithecus, most of the species can be determined +with certainty. In the American genus Cebus, the various forms are ranked +by some naturalists as species, by others as mere geographical races. Now +if numerous specimens of Cebus were collected from all parts of South +America, and those forms which at present appear to be specifically +distinct, were found to graduate into each other by close steps, they would +usually be ranked as mere varieties or races; and this course has been +followed by most naturalists with respect to the races of man. +Nevertheless, it must be confessed that there are forms, at least in the +vegetable kingdom (19. Prof. Nageli has carefully described several +striking cases in his 'Botanische Mittheilungen,' B. ii. 1866, ss. 294-369. +Prof. Asa Gray has made analogous remarks on some intermediate forms in the +Compositae of N. America.), which we cannot avoid naming as species, but +which are connected together by numberless gradations, independently of +intercrossing. + +Some naturalists have lately employed the term "sub-species" to designate +forms which possess many of the characteristics of true species, but which +hardly deserve so high a rank. Now if we reflect on the weighty arguments +above given, for raising the races of man to the dignity of species, and +the insuperable difficulties on the other side in defining them, it seems +that the term "sub-species" might here be used with propriety. But from +long habit the term "race" will perhaps always be employed. The choice of +terms is only so far important in that it is desirable to use, as far as +possible, the same terms for the same degrees of difference. Unfortunately +this can rarely be done: for the larger genera generally include closely- +allied forms, which can be distinguished only with much difficulty, whilst +the smaller genera within the same family include forms that are perfectly +distinct; yet all must be ranked equally as species. So again, species +within the same large genus by no means resemble each other to the same +degree: on the contrary, some of them can generally be arranged in little +groups round other species, like satellites round planets. (20. 'Origin +of Species,' 5th edit. p. 68.) + +The question whether mankind consists of one or several species has of late +years been much discussed by anthropologists, who are divided into the two +schools of monogenists and polygenists. Those who do not admit the +principle of evolution, must look at species as separate creations, or in +some manner as distinct entities; and they must decide what forms of man +they will consider as species by the analogy of the method commonly pursued +in ranking other organic beings as species. But it is a hopeless endeavour +to decide this point, until some definition of the term "species" is +generally accepted; and the definition must not include an indeterminate +element such as an act of creation. We might as well attempt without any +definition to decide whether a certain number of houses should be called a +village, town, or city. We have a practical illustration of the difficulty +in the never-ending doubts whether many closely-allied mammals, birds, +insects, and plants, which represent each other respectively in North +America and Europe, should be ranked as species or geographical races; and +the like holds true of the productions of many islands situated at some +little distance from the nearest continent. + +Those naturalists, on the other hand, who admit the principle of evolution, +and this is now admitted by the majority of rising men, will feel no doubt +that all the races of man are descended from a single primitive stock; +whether or not they may think fit to designate the races as distinct +species, for the sake of expressing their amount of difference. (21. See +Prof. Huxley to this effect in the 'Fortnightly Review,' 1865, p. 275.) +With our domestic animals the question whether the various races have +arisen from one or more species is somewhat different. Although it may be +admitted that all the races, as well as all the natural species within the +same genus, have sprung from the same primitive stock, yet it is a fit +subject for discussion, whether all the domestic races of the dog, for +instance, have acquired their present amount of difference since some one +species was first domesticated by man; or whether they owe some of their +characters to inheritance from distinct species, which had already been +differentiated in a state of nature. With man no such question can arise, +for he cannot be said to have been domesticated at any particular period. + +During an early stage in the divergence of the races of man from a common +stock, the differences between the races and their number must have been +small; consequently as far as their distinguishing characters are +concerned, they then had less claim to rank as distinct species than the +existing so-called races. Nevertheless, so arbitrary is the term of +species, that such early races would perhaps have been ranked by some +naturalists as distinct species, if their differences, although extremely +slight, had been more constant than they are at present, and had not +graduated into each other. + +It is however possible, though far from probable, that the early +progenitors of man might formerly have diverged much in character, until +they became more unlike each other than any now existing races; but that +subsequently, as suggested by Vogt (22. 'Lectures on Man,' Eng. translat., +1864, p. 468.), they converged in character. When man selects the +offspring of two distinct species for the same object, he sometimes induces +a considerable amount of convergence, as far as general appearance is +concerned. This is the case, as shewn by von Nathusius (23. 'Die Rassen +des Schweines,' 1860, s. 46. 'Vorstudien für Geschichte,' etc., +Schweinesschädel, 1864, s. 104. With respect to cattle, see M. de +Quatrefages, 'Unité de l'Espèce Humaine,' 1861, p. 119.), with the improved +breeds of the pig, which are descended from two distinct species; and in a +less marked manner with the improved breeds of cattle. A great anatomist, +Gratiolet, maintains that the anthropomorphous apes do not form a natural +sub-group; but that the orang is a highly developed gibbon or +semnopithecus, the chimpanzee a highly developed macacus, and the gorilla a +highly developed mandrill. If this conclusion, which rests almost +exclusively on brain-characters, be admitted, we should have a case of +convergence at least in external characters, for the anthropomorphous apes +are certainly more like each other in many points, than they are to other +apes. All analogical resemblances, as of a whale to a fish, may indeed be +said to be cases of convergence; but this term has never been applied to +superficial and adaptive resemblances. It would, however, be extremely +rash to attribute to convergence close similarity of character in many +points of structure amongst the modified descendants of widely distinct +beings. The form of a crystal is determined solely by the molecular +forces, and it is not surprising that dissimilar substances should +sometimes assume the same form; but with organic beings we should bear in +mind that the form of each depends on an infinity of complex relations, +namely on variations, due to causes far too intricate to be followed,--on +the nature of the variations preserved, these depending on the physical +conditions, and still more on the surrounding organisms which compete with +each,--and lastly, on inheritance (in itself a fluctuating element) from +innumerable progenitors, all of which have had their forms determined +through equally complex relations. It appears incredible that the modified +descendants of two organisms, if these differed from each other in a marked +manner, should ever afterwards converge so closely as to lead to a near +approach to identity throughout their whole organisation. In the case of +the convergent races of pigs above referred to, evidence of their descent +from two primitive stocks is, according to von Nathusius, still plainly +retained, in certain bones of their skulls. If the races of man had +descended, as is supposed by some naturalists, from two or more species, +which differed from each other as much, or nearly as much, as does the +orang from the gorilla, it can hardly be doubted that marked differences in +the structure of certain bones would still be discoverable in man as he now +exists. + +Although the existing races of man differ in many respects, as in colour, +hair, shape of skull, proportions of the body, etc., yet if their whole +structure be taken into consideration they are found to resemble each other +closely in a multitude of points. Many of these are of so unimportant or +of so singular a nature, that it is extremely improbable that they should +have been independently acquired by aboriginally distinct species or races. +The same remark holds good with equal or greater force with respect to the +numerous points of mental similarity between the most distinct races of +man. The American aborigines, Negroes and Europeans are as different from +each other in mind as any three races that can be named; yet I was +incessantly struck, whilst living with the Feugians on board the "Beagle," +with the many little traits of character, shewing how similar their minds +were to ours; and so it was with a full-blooded negro with whom I happened +once to be intimate. + +He who will read Mr. Tylor's and Sir J. Lubbock's interesting works (24. +Tylor's 'Early History of Mankind,' 1865: with respect to gesture- +language, see p. 54. Lubbock's 'Prehistoric Times,' 2nd edit. 1869.) can +hardly fail to be deeply impressed with the close similarity between the +men of all races in tastes, dispositions and habits. This is shewn by the +pleasure which they all take in dancing, rude music, acting, painting, +tattooing, and otherwise decorating themselves; in their mutual +comprehension of gesture-language, by the same expression in their +features, and by the same inarticulate cries, when excited by the same +emotions. This similarity, or rather identity, is striking, when +contrasted with the different expressions and cries made by distinct +species of monkeys. There is good evidence that the art of shooting with +bows and arrows has not been handed down from any common progenitor of +mankind, yet as Westropp and Nilsson have remarked (25. 'On Analogous +Forms of Implements,' in 'Memoirs of Anthropological Society' by H.M. +Westropp. 'The Primitive Inhabitants of Scandinavia,' Eng. translat., +edited by Sir J. Lubbock, 1868, p. 104.), the stone arrow-heads, brought +from the most distant parts of the world, and manufactured at the most +remote periods, are almost identical; and this fact can only be accounted +for by the various races having similar inventive or mental powers. The +same observation has been made by archaeologists (26. Westropp 'On +Cromlechs,' etc., 'Journal of Ethnological Soc.' as given in 'Scientific +Opinion,' June 2nd, 1869, p. 3.) with respect to certain widely-prevalent +ornaments, such as zig-zags, etc.; and with respect to various simple +beliefs and customs, such as the burying of the dead under megalithic +structures. I remember observing in South America (27. 'Journal of +Researches: Voyage of the "Beagle,"' p. 46.), that there, as in so many +other parts of the world, men have generally chosen the summits of lofty +hills, to throw up piles of stones, either as a record of some remarkable +event, or for burying their dead. + +Now when naturalists observe a close agreement in numerous small details of +habits, tastes, and dispositions between two or more domestic races, or +between nearly-allied natural forms, they use this fact as an argument that +they are descended from a common progenitor who was thus endowed; and +consequently that all should be classed under the same species. The same +argument may be applied with much force to the races of man. + +As it is improbable that the numerous and unimportant points of resemblance +between the several races of man in bodily structure and mental faculties +(I do not here refer to similar customs) should all have been independently +acquired, they must have been inherited from progenitors who had these same +characters. We thus gain some insight into the early state of man, before +he had spread step by step over the face of the earth. The spreading of +man to regions widely separated by the sea, no doubt, preceded any great +amount of divergence of character in the several races; for otherwise we +should sometimes meet with the same race in distinct continents; and this +is never the case. Sir J. Lubbock, after comparing the arts now practised +by savages in all parts of the world, specifies those which man could not +have known, when he first wandered from his original birthplace; for if +once learnt they would never have been forgotten. (28. 'Prehistoric +Times,' 1869, p. 574.) He thus shews that "the spear, which is but a +development of the knife-point, and the club, which is but a long hammer, +are the only things left." He admits, however, that the art of making fire +probably had been already discovered, for it is common to all the races now +existing, and was known to the ancient cave-inhabitants of Europe. Perhaps +the art of making rude canoes or rafts was likewise known; but as man +existed at a remote epoch, when the land in many places stood at a very +different level to what it does now, he would have been able, without the +aid of canoes, to have spread widely. Sir J. Lubbock further remarks how +improbable it is that our earliest ancestors could have "counted as high as +ten, considering that so many races now in existence cannot get beyond +four." Nevertheless, at this early period, the intellectual and social +faculties of man could hardly have been inferior in any extreme degree to +those possessed at present by the lowest savages; otherwise primeval man +could not have been so eminently successful in the struggle for life, as +proved by his early and wide diffusion. + +From the fundamental differences between certain languages, some +philologists have inferred that when man first became widely diffused, he +was not a speaking animal; but it may be suspected that languages, far less +perfect than any now spoken, aided by gestures, might have been used, and +yet have left no traces on subsequent and more highly-developed tongues. +Without the use of some language, however imperfect, it appears doubtful +whether man's intellect could have risen to the standard implied by his +dominant position at an early period. + +Whether primeval man, when he possessed but few arts, and those of the +rudest kind, and when his power of language was extremely imperfect, would +have deserved to be called man, must depend on the definition which we +employ. In a series of forms graduating insensibly from some ape-like +creature to man as he now exists, it would be impossible to fix on any +definite point where the term "man" ought to be used. But this is a matter +of very little importance. So again, it is almost a matter of indifference +whether the so-called races of man are thus designated, or are ranked as +species or sub-species; but the latter term appears the more appropriate. +Finally, we may conclude that when the principle of evolution is generally +accepted, as it surely will be before long, the dispute between the +monogenists and the polygenists will die a silent and unobserved death. + +One other question ought not to be passed over without notice, namely, +whether, as is sometimes assumed, each sub-species or race of man has +sprung from a single pair of progenitors. With our domestic animals a new +race can readily be formed by carefully matching the varying offspring from +a single pair, or even from a single individual possessing some new +character; but most of our races have been formed, not intentionally from a +selected pair, but unconsciously by the preservation of many individuals +which have varied, however slightly, in some useful or desired manner. If +in one country stronger and heavier horses, and in another country lighter +and fleeter ones, were habitually preferred, we may feel sure that two +distinct sub-breeds would be produced in the course of time, without any +one pair having been separated and bred from, in either country. Many +races have been thus formed, and their manner of formation is closely +analogous to that of natural species. We know, also, that the horses taken +to the Falkland Islands have, during successive generations, become smaller +and weaker, whilst those which have run wild on the Pampas have acquired +larger and coarser heads; and such changes are manifestly due, not to any +one pair, but to all the individuals having been subjected to the same +conditions, aided, perhaps, by the principle of reversion. The new sub- +breeds in such cases are not descended from any single pair, but from many +individuals which have varied in different degrees, but in the same general +manner; and we may conclude that the races of man have been similarly +produced, the modifications being either the direct result of exposure to +different conditions, or the indirect result of some form of selection. +But to this latter subject we shall presently return. + +ON THE EXTINCTION OF THE RACES OF MAN. + +The partial or complete extinction of many races and sub-races of man is +historically known. Humboldt saw in South America a parrot which was the +sole living creature that could speak a word of the language of a lost +tribe. Ancient monuments and stone implements found in all parts of the +world, about which no tradition has been preserved by the present +inhabitants, indicate much extinction. Some small and broken tribes, +remnants of former races, still survive in isolated and generally +mountainous districts. In Europe the ancient races were all, according to +Shaaffhausen (29. Translation in 'Anthropological Review,' Oct. 1868, p. +431.), "lower in the scale than the rudest living savages"; they must +therefore have differed, to a certain extent, from any existing race. The +remains described by Professor Broca from Les Eyzies, though they +unfortunately appear to have belonged to a single family, indicate a race +with a most singular combination of low or simious, and of high +characteristics. This race is "entirely different from any other, ancient +or modern, that we have heard of." (30. 'Transactions, International +Congress of Prehistoric Archaeology' 1868, pp. 172-175. See also Broca +(tr.) in 'Anthropological Review,' Oct. 1868, p. 410.) It differed, +therefore, from the quaternary race of the caverns of Belgium. + +Man can long resist conditions which appear extremely unfavourable for his +existence. (31. Dr. Gerland, 'Ueber das Aussterben der Naturvölker,' +1868, s. 82.) He has long lived in the extreme regions of the North, with +no wood for his canoes or implements, and with only blubber as fuel, and +melted snow as drink. In the southern extremity of America the Fuegians +survive without the protection of clothes, or of any building worthy to be +called a hovel. In South Africa the aborigines wander over arid plains, +where dangerous beasts abound. Man can withstand the deadly influence of +the Terai at the foot of the Himalaya, and the pestilential shores of +tropical Africa. + +Extinction follows chiefly from the competition of tribe with tribe, and +race with race. Various checks are always in action, serving to keep down +the numbers of each savage tribe,--such as periodical famines, nomadic +habits and the consequent deaths of infants, prolonged suckling, wars, +accidents, sickness, licentiousness, the stealing of women, infanticide, +and especially lessened fertility. If any one of these checks increases in +power, even slightly, the tribe thus affected tends to decrease; and when +of two adjoining tribes one becomes less numerous and less powerful than +the other, the contest is soon settled by war, slaughter, cannibalism, +slavery, and absorption. Even when a weaker tribe is not thus abruptly +swept away, if it once begins to decrease, it generally goes on decreasing +until it becomes extinct. (32. Gerland (ibid. s. 12) gives facts in +support of this statement.) + +When civilised nations come into contact with barbarians the struggle is +short, except where a deadly climate gives its aid to the native race. Of +the causes which lead to the victory of civilised nations, some are plain +and simple, others complex and obscure. We can see that the cultivation of +the land will be fatal in many ways to savages, for they cannot, or will +not, change their habits. New diseases and vices have in some cases proved +highly destructive; and it appears that a new disease often causes much +death, until those who are most susceptible to its destructive influence +are gradually weeded out (33. See remarks to this effect in Sir H. +Holland's 'Medical Notes and Reflections,' 1839, p. 390.); and so it may be +with the evil effects from spirituous liquors, as well as with the +unconquerably strong taste for them shewn by so many savages. It further +appears, mysterious as is the fact, that the first meeting of distinct and +separated people generates disease. (34. I have collected ('Journal of +Researches: Voyage of the "Beagle,"' p. 435) a good many cases bearing on +this subject; see also Gerland, ibid. s. 8. Poeppig speaks of the "breath +of civilisation as poisonous to savages.") Mr. Sproat, who in Vancouver +Island closely attended to the subject of extinction, believed that changed +habits of life, consequent on the advent of Europeans, induces much ill +health. He lays, also, great stress on the apparently trifling cause that +the natives become "bewildered and dull by the new life around them; they +lose the motives for exertion, and get no new ones in their place." (35. +Sproat, 'Scenes and Studies of Savage Life,' 1868, p. 284.) + +The grade of their civilisation seems to be a most important element in the +success of competing nations. A few centuries ago Europe feared the +inroads of Eastern barbarians; now any such fear would be ridiculous. It +is a more curious fact, as Mr. Bagehot has remarked, that savages did not +formerly waste away before the classical nations, as they now do before +modern civilised nations; had they done so, the old moralists would have +mused over the event; but there is no lament in any writer of that period +over the perishing barbarians. (36. Bagehot, 'Physics and Politics,' +'Fortnightly Review,' April 1, 1868, p. 455.) The most potent of all the +causes of extinction, appears in many cases to be lessened fertility and +ill-health, especially amongst the children, arising from changed +conditions of life, notwithstanding that the new conditions may not be +injurious in themselves. I am much indebted to Mr. H.H. Howorth for having +called my attention to this subject, and for having given me information +respecting it. I have collected the following cases. + +When Tasmania was first colonised the natives were roughly estimated by +some at 7000 and by others at 20,000. Their number was soon greatly +reduced, chiefly by fighting with the English and with each other. After +the famous hunt by all the colonists, when the remaining natives delivered +themselves up to the government, they consisted only of 120 individuals +(37. All the statements here given are taken from 'The Last of the +Tasmanians,' by J. Bonwick, 1870.), who were in 1832 transported to +Flinders Island. This island, situated between Tasmania and Australia, is +forty miles long, and from twelve to eighteen miles broad: it seems +healthy, and the natives were well treated. Nevertheless, they suffered +greatly in health. In 1834 they consisted (Bonwick, p. 250) of forty-seven +adult males, forty-eight adult females, and sixteen children, or in all of +111 souls. In 1835 only one hundred were left. As they continued rapidly +to decrease, and as they themselves thought that they should not perish so +quickly elsewhere, they were removed in 1847 to Oyster Cove in the southern +part of Tasmania. They then consisted (Dec. 20th, 1847) of fourteen men, +twenty-two women and ten children. (38. This is the statement of the +Governor of Tasmania, Sir W. Denison, 'Varieties of Vice-Regal Life,' 1870, +vol. i. p. 67.) But the change of site did no good. Disease and death +still pursued them, and in 1864 one man (who died in 1869), and three +elderly women alone survived. The infertility of the women is even a more +remarkable fact than the liability of all to ill-health and death. At the +time when only nine women were left at Oyster Cove, they told Mr. Bonwick +(p. 386), that only two had ever borne children: and these two had +together produced only three children! + +With respect to the cause of this extraordinary state of things, Dr. Story +remarks that death followed the attempts to civilise the natives. "If left +to themselves to roam as they were wont and undisturbed, they would have +reared more children, and there would have been less mortality." Another +careful observer of the natives, Mr. Davis, remarks, "The births have been +few and the deaths numerous. This may have been in a great measure owing +to their change of living and food; but more so to their banishment from +the mainland of Van Diemen's Land, and consequent depression of spirits" +(Bonwick, pp. 388, 390). + +Similar facts have been observed in two widely different parts of +Australia. The celebrated explorer, Mr. Gregory, told Mr. Bonwick, that in +Queensland "the want of reproduction was being already felt with the +blacks, even in the most recently settled parts, and that decay would set +in." Of thirteen aborigines from Shark's Bay who visited Murchison River, +twelve died of consumption within three months. (39. For these cases, see +Bonwick's 'Daily Life of the Tasmanians,' 1870, p. 90: and the 'Last of +the Tasmanians,' 1870, p. 386.) + +The decrease of the Maories of New Zealand has been carefully investigated +by Mr. Fenton, in an admirable Report, from which all the following +statements, with one exception, are taken. (40. 'Observations on the +Aboriginal Inhabitants of New Zealand,' published by the Government, 1859.) +The decrease in number since 1830 is admitted by every one, including the +natives themselves, and is still steadily progressing. Although it has +hitherto been found impossible to take an actual census of the natives, +their numbers were carefully estimated by residents in many districts. The +result seems trustworthy, and shows that during the fourteen years, +previous to 1858, the decrease was 19.42 per cent. Some of the tribes, +thus carefully examined, lived above a hundred miles apart, some on the +coast, some inland; and their means of subsistence and habits differed to a +certain extent (p. 28). The total number in 1858 was believed to be +53,700, and in 1872, after a second interval of fourteen years, another +census was taken, and the number is given as only 36,359, shewing a +decrease of 32.29 per cent! (41. 'New Zealand,' by Alex. Kennedy, 1873, +p. 47.) Mr. Fenton, after shewing in detail the insufficiency of the +various causes, usually assigned in explanation of this extraordinary +decrease, such as new diseases, the profligacy of the women, drunkenness, +wars, etc., concludes on weighty grounds that it depends chiefly on the +unproductiveness of the women, and on the extraordinary mortality of the +young children (pp. 31, 34). In proof of this he shews (p. 33) that in +1844 there was one non-adult for every 2.57 adults; whereas in 1858 there +was only one non-adult for every 3.27 adults. The mortality of the adults +is also great. He adduces as a further cause of the decrease the +inequality of the sexes; for fewer females are born than males. To this +latter point, depending perhaps on a widely distinct cause, I shall return +in a future chapter. Mr. Fenton contrasts with astonishment the decrease +in New Zealand with the increase in Ireland; countries not very dissimilar +in climate, and where the inhabitants now follow nearly similar habits. +The Maories themselves (p. 35) "attribute their decadence, in some measure, +to the introduction of new food and clothing, and the attendant change of +habits"; and it will be seen, when we consider the influence of changed +conditions on fertility, that they are probably right. The diminution +began between the years 1830 and 1840; and Mr. Fenton shews (p. 40) that +about 1830, the art of manufacturing putrid corn (maize), by long steeping +in water, was discovered and largely practised; and this proves that a +change of habits was beginning amongst the natives, even when New Zealand +was only thinly inhabited by Europeans. When I visited the Bay of Islands +in 1835, the dress and food of the inhabitants had already been much +modified: they raised potatoes, maize, and other agricultural produce, and +exchanged them for English manufactured goods and tobacco. + +It is evident from many statements in the life of Bishop Patteson (42. +'Life of J.C. Patteson,' by C.M. Younge, 1874; see more especially vol. i. +p. 530.), that the Melanesians of the New Hebrides and neighbouring +archipelagoes, suffered to an extraordinary degree in health, and perished +in large numbers, when they were removed to New Zealand, Norfolk Island, +and other salubrious places, in order to be educated as missionaries. + +The decrease of the native population of the Sandwich Islands is as +notorious as that of New Zealand. It has been roughly estimated by those +best capable of judging, that when Cook discovered the Islands in 1779, the +population amounted to about 300,000. According to a loose census in 1823, +the numbers then were 142,050. In 1832, and at several subsequent periods, +an accurate census was officially taken, but I have been able to obtain +only the following returns: + Native Population Annual rate of decrease + per cent., assuming it to + (Except during 1832 and have been uniform between + 1836, when the few the successive censuses; + foreigners in the islands these censuses being taken + Year were included.) at irregular intervals. + + 1832 130,313 + 4.46 + 1836 108,579 + 2.47 + 1853 71,019 + 0.81 + 1860 67,084 + 2.18 + 1866 58,765 + 2.17 + 1872 51,531 + +We here see that in the interval of forty years, between 1832 and 1872, the +population has decreased no less than sixty-eight per cent.! This has been +attributed by most writers to the profligacy of the women, to former bloody +wars, and to the severe labour imposed on conquered tribes and to newly +introduced diseases, which have been on several occasions extremely +destructive. No doubt these and other such causes have been highly +efficient, and may account for the extraordinary rate of decrease between +the years 1832 and 1836; but the most potent of all the causes seems to be +lessened fertility. According to Dr. Ruschenberger of the U.S. Navy, who +visited these islands between 1835 and 1837, in one district of Hawaii, +only twenty-five men out of 1134, and in another district only ten out of +637, had a family with as many as three children. Of eighty married women, +only thirty-nine had ever borne children; and "the official report gives an +average of half a child to each married couple in the whole island." This +is almost exactly the same average as with the Tasmanians at Oyster Cove. +Jarves, who published his History in 1843, says that "families who have +three children are freed from all taxes; those having more, are rewarded by +gifts of land and other encouragements." This unparalleled enactment by +the government well shews how infertile the race had become. The Rev. A. +Bishop stated in the Hawaiian 'Spectator' in 1839, that a large proportion +of the children die at early ages, and Bishop Staley informs me that this +is still the case, just as in New Zealand. This has been attributed to the +neglect of the children by the women, but it is probably in large part due +to innate weakness of constitution in the children, in relation to the +lessened fertility of their parents. There is, moreover, a further +resemblance to the case of New Zealand, in the fact that there is a large +excess of male over female births: the census of 1872 gives 31,650 males +to 25,247 females of all ages, that is 125.36 males for every 100 females; +whereas in all civilised countries the females exceed the males. No doubt +the profligacy of the women may in part account for their small fertility; +but their changed habits of life is a much more probable cause, and which +will at the same time account for the increased mortality, especially of +the children. The islands were visited by Cook in 1779, Vancouver in 1794, +and often subsequently by whalers. In 1819 missionaries arrived, and found +that idolatry had been already abolished, and other changes effected by the +king. After this period there was a rapid change in almost all the habits +of life of the natives, and they soon became "the most civilised of the +Pacific Islanders." One of my informants, Mr. Coan, who was born on the +islands, remarks that the natives have undergone a greater change in their +habits of life in the course of fifty years than Englishmen during a +thousand years. From information received from Bishop Staley, it does not +appear that the poorer classes have ever much changed their diet, although +many new kinds of fruit have been introduced, and the sugar-cane is in +universal use. Owing, however, to their passion for imitating Europeans, +they altered their manner of dressing at an early period, and the use of +alcoholic drinks became very general. Although these changes appear +inconsiderable, I can well believe, from what is known with respect to +animals, that they might suffice to lessen the fertility of the natives. +(43. The foregoing statements are taken chiefly from the following works: +Jarves' 'History of the Hawaiian Islands,' 1843, pp. 400-407. Cheever, +'Life in the Sandwich Islands,' 1851, p. 277. Ruschenberger is quoted by +Bonwick, 'Last of the Tasmanians,' 1870, p. 378. Bishop is quoted by Sir +E. Belcher, 'Voyage Round the World,' 1843, vol. i. p. 272. I owe the +census of the several years to the kindness of Mr. Coan, at the request of +Dr. Youmans of New York; and in most cases I have compared the Youmans +figures with those given in several of the above-named works. I have +omitted the census for 1850, as I have seen two widely different numbers +given.) + +Lastly, Mr. Macnamara states (44. 'The Indian Medical Gazette,' Nov. 1, +1871, p. 240.) that the low and degraded inhabitants of the Andaman +Islands, on the eastern side of the Gulf of Bengal, are "eminently +susceptible to any change of climate: in fact, take them away from their +island homes, and they are almost certain to die, and that independently of +diet or extraneous influences." He further states that the inhabitants of +the Valley of Nepal, which is extremely hot in summer, and also the various +hill-tribes of India, suffer from dysentery and fever when on the plains; +and they die if they attempt to pass the whole year there. + +We thus see that many of the wilder races of man are apt to suffer much in +health when subjected to changed conditions or habits of life, and not +exclusively from being transported to a new climate. Mere alterations in +habits, which do not appear injurious in themselves, seem to have this same +effect; and in several cases the children are particularly liable to +suffer. It has often been said, as Mr. Macnamara remarks, that man can +resist with impunity the greatest diversities of climate and other changes; +but this is true only of the civilised races. Man in his wild condition +seems to be in this respect almost as susceptible as his nearest allies, +the anthropoid apes, which have never yet survived long, when removed from +their native country. + +Lessened fertility from changed conditions, as in the case of the +Tasmanians, Maories, Sandwich Islanders, and apparently the Australians, is +still more interesting than their liability to ill-health and death; for +even a slight degree of infertility, combined with those other causes which +tend to check the increase of every population, would sooner or later lead +to extinction. The diminution of fertility may be explained in some cases +by the profligacy of the women (as until lately with the Tahitians), but +Mr. Fenton has shewn that this explanation by no means suffices with the +New Zealanders, nor does it with the Tasmanians. + +In the paper above quoted, Mr. Macnamara gives reasons for believing that +the inhabitants of districts subject to malaria are apt to be sterile; but +this cannot apply in several of the above cases. Some writers have +suggested that the aborigines of islands have suffered in fertility and +health from long continued inter-breeding; but in the above cases +infertility has coincided too closely with the arrival of Europeans for us +to admit this explanation. Nor have we at present any reason to believe +that man is highly sensitive to the evil effects of inter-breeding, +especially in areas so large as New Zealand, and the Sandwich archipelago +with its diversified stations. On the contrary, it is known that the +present inhabitants of Norfolk Island are nearly all cousins or near +relations, as are the Todas in India, and the inhabitants of some of the +Western Islands of Scotland; and yet they seem not to have suffered in +fertility. (45. On the close relationship of the Norfolk Islanders, Sir +W. Denison, 'Varieties of Vice-Regal Life,' vol. i. 1870, p. 410. For the +Todas, see Col. Marshall's work 1873, p. 110. For the Western Islands of +Scotland, Dr. Mitchell, 'Edinburgh Medical Journal,' March to June, 1865.) + +A much more probable view is suggested by the analogy of the lower animals. +The reproductive system can be shewn to be susceptible to an extraordinary +degree (though why we know not) to changed conditions of life; and this +susceptibility leads both to beneficial and to evil results. A large +collection of facts on this subject is given in chap. xviii. of vol. ii. of +my 'Variation of Animals and Plants under Domestication,' I can here give +only the briefest abstract; and every one interested in the subject may +consult the above work. Very slight changes increase the health, vigour, +and fertility of most or all organic beings, whilst other changes are known +to render a large number of animals sterile. One of the most familiar +cases, is that of tamed elephants not breeding in India; though they often +breed in Ava, where the females are allowed to roam about the forests to +some extent, and are thus placed under more natural conditions. The case +of various American monkeys, both sexes of which have been kept for many +years together in their own countries, and yet have very rarely or never +bred, is a more apposite instance, because of their relationship to man. +It is remarkable how slight a change in the conditions often induces +sterility in a wild animal when captured; and this is the more strange as +all our domesticated animals have become more fertile than they were in a +state of nature; and some of them can resist the most unnatural conditions +with undiminished fertility. (46. For the evidence on this head, see +'Variation of Animals,' etc., vol. ii. p. 111.) Certain groups of animals +are much more liable than others to be affected by captivity; and generally +all the species of the same group are affected in the same manner. But +sometimes a single species in a group is rendered sterile, whilst the +others are not so; on the other hand, a single species may retain its +fertility whilst most of the others fail to breed. The males and females +of some species when confined, or when allowed to live almost, but not +quite free, in their native country, never unite; others thus circumstanced +frequently unite but never produce offspring; others again produce some +offspring, but fewer than in a state of nature; and as bearing on the above +cases of man, it is important to remark that the young are apt to be weak +and sickly, or malformed, and to perish at an early age. + +Seeing how general is this law of the susceptibility of the reproductive +system to changed conditions of life, and that it holds good with our +nearest allies, the Quadrumana, I can hardly doubt that it applies to man +in his primeval state. Hence if savages of any race are induced suddenly +to change their habits of life, they become more or less sterile, and their +young offspring suffer in health, in the same manner and from the same +cause, as do the elephant and hunting-leopard in India, many monkeys in +America, and a host of animals of all kinds, on removal from their natural +conditions. + +We can see why it is that aborigines, who have long inhabited islands, and +who must have been long exposed to nearly uniform conditions, should be +specially affected by any change in their habits, as seems to be the case. +Civilised races can certainly resist changes of all kinds far better than +savages; and in this respect they resemble domesticated animals, for though +the latter sometimes suffer in health (for instance European dogs in +India), yet they are rarely rendered sterile, though a few such instances +have been recorded. (47. 'Variation of Animals,' etc., vol. ii. p. 16.) +The immunity of civilised races and domesticated animals is probably due to +their having been subjected to a greater extent, and therefore having grown +somewhat more accustomed, to diversified or varying conditions, than the +majority of wild animals; and to their having formerly immigrated or been +carried from country to country, and to different families or sub-races +having inter-crossed. It appears that a cross with civilised races at once +gives to an aboriginal race an immunity from the evil consequences of +changed conditions. Thus the crossed offspring from the Tahitians and +English, when settled in Pitcairn Island, increased so rapidly that the +island was soon overstocked; and in June 1856 they were removed to Norfolk +Island. They then consisted of 60 married persons and 134 children, making +a total of 194. Here they likewise increased so rapidly, that although +sixteen of them returned to Pitcairn Island in 1859, they numbered in +January 1868, 300 souls; the males and females being in exactly equal +numbers. What a contrast does this case present with that of the +Tasmanians; the Norfolk Islanders INCREASED in only twelve and a half years +from 194 to 300; whereas the Tasmanians DECREASED during fifteen years from +120 to 46, of which latter number only ten were children. (48. These +details are taken from 'The Mutineers of the "Bounty,"' by Lady Belcher, +1870; and from 'Pitcairn Island,' ordered to be printed by the House of +Commons, May 29, 1863. The following statements about the Sandwich +Islanders are from the 'Honolulu Gazette,' and from Mr. Coan.) + +So again in the interval between the census of 1866 and 1872 the natives of +full blood in the Sandwich Islands decreased by 8081, whilst the half- +castes, who are believed to be healthier, increased by 847; but I do not +know whether the latter number includes the offspring from the half-castes, +or only the half-castes of the first generation. + +The cases which I have here given all relate to aborigines, who have been +subjected to new conditions as the result of the immigration of civilised +men. But sterility and ill-health would probably follow, if savages were +compelled by any cause, such as the inroad of a conquering tribe, to desert +their homes and to change their habits. It is an interesting circumstance +that the chief check to wild animals becoming domesticated, which implies +the power of their breeding freely when first captured, and one chief check +to wild men, when brought into contact with civilisation, surviving to form +a civilised race, is the same, namely, sterility from changed conditions of +life. + +Finally, although the gradual decrease and ultimate extinction of the races +of man is a highly complex problem, depending on many causes which differ +in different places and at different times; it is the same problem as that +presented by the extinction of one of the higher animals--of the fossil +horse, for instance, which disappeared from South America, soon afterwards +to be replaced, within the same districts, by countless troups of the +Spanish horse. The New Zealander seems conscious of this parallelism, for +he compares his future fate with that of the native rat now almost +exterminated by the European rat. Though the difficulty is great to our +imagination, and really great, if we wish to ascertain the precise causes +and their manner of action, it ought not to be so to our reason, as long as +we keep steadily in mind that the increase of each species and each race is +constantly checked in various ways; so that if any new check, even a slight +one, be superadded, the race will surely decrease in number; and decreasing +numbers will sooner or later lead to extinction; the end, in most cases, +being promptly determined by the inroads of conquering tribes. + +ON THE FORMATION OF THE RACES OF MAN. + +In some cases the crossing of distinct races has led to the formation of a +new race. The singular fact that the Europeans and Hindoos, who belong to +the same Aryan stock, and speak a language fundamentally the same, differ +widely in appearance, whilst Europeans differ but little from Jews, who +belong to the Semitic stock, and speak quite another language, has been +accounted for by Broca (49. 'On Anthropology,' translation, +'Anthropological Review,' Jan. 1868, p. 38.), through certain Aryan +branches having been largely crossed by indigenous tribes during their wide +diffusion. When two races in close contact cross, the first result is a +heterogeneous mixture: thus Mr. Hunter, in describing the Santali or hill- +tribes of India, says that hundreds of imperceptible gradations may be +traced "from the black, squat tribes of the mountains to the tall olive- +coloured Brahman, with his intellectual brow, calm eyes, and high but +narrow head"; so that it is necessary in courts of justice to ask the +witnesses whether they are Santalis or Hindoos. (50. 'The Annals of Rural +Bengal,' 1868, p. 134.) Whether a heterogeneous people, such as the +inhabitants of some of the Polynesian islands, formed by the crossing of +two distinct races, with few or no pure members left, would ever become +homogeneous, is not known from direct evidence. But as with our +domesticated animals, a cross-breed can certainly be fixed and made uniform +by careful selection (51. 'The Variation of Animals and Plants under +Domestication,' vol. ii. p. 95.) in the course of a few generations, we may +infer that the free intercrossing of a heterogeneous mixture during a long +descent would supply the place of selection, and overcome any tendency to +reversion; so that the crossed race would ultimately become homogeneous, +though it might not partake in an equal degree of the characters of the two +parent-races. + +Of all the differences between the races of man, the colour of the skin is +the most conspicuous and one of the best marked. It was formerly thought +that differences of this kind could be accounted for by long exposure to +different climates; but Pallas first shewed that this is not tenable, and +he has since been followed by almost all anthropologists. (52. Pallas, +'Act. Acad. St. Petersburg,' 1780, part ii. p. 69. He was followed by +Rudolphi, in his 'Beytrage zur Anthropologie,' 1812. An excellent summary +of the evidence is given by Godron, 'De l'Espèce,' 1859, vol. ii. p. 246, +etc.) This view has been rejected chiefly because the distribution of the +variously coloured races, most of whom must have long inhabited their +present homes, does not coincide with corresponding differences of climate. +Some little weight may be given to such cases as that of the Dutch +families, who, as we hear on excellent authority (53. Sir Andrew Smith, as +quoted by Knox, 'Races of Man,' 1850, p. 473.), have not undergone the +least change of colour after residing for three centuries in South Africa. +An argument on the same side may likewise be drawn from the uniform +appearance in various parts of the world of gipsies and Jews, though the +uniformity of the latter has been somewhat exaggerated. (54. See De +Quatrefages on this head, 'Revue des Cours Scientifiques,' Oct. 17, 1868, +p. 731.) A very damp or a very dry atmosphere has been supposed to be more +influential in modifying the colour of the skin than mere heat; but as +D'Orbigny in South America, and Livingstone in Africa, arrived at +diametrically opposite conclusions with respect to dampness and dryness, +any conclusion on this head must be considered as very doubtful. (55. +Livingstone's 'Travels and Researches in S. Africa,' 1857, pp. 338, 339. +D'Orbigny, as quoted by Godron, 'De l'Espece,' vol. ii. p. 266.) + +Various facts, which I have given elsewhere, prove that the colour of the +skin and hair is sometimes correlated in a surprising manner with a +complete immunity from the action of certain vegetable poisons, and from +the attacks of certain parasites. Hence it occurred to me, that negroes +and other dark races might have acquired their dark tints by the darker +individuals escaping from the deadly influence of the miasma of their +native countries, during a long series of generations. + +I afterwards found that this same idea had long ago occurred to Dr. Wells. +(56. See a paper read before the Royal Soc. in 1813, and published in his +Essays in 1818. I have given an account of Dr. Wells' views in the +Historical Sketch (p. xvi.) to my 'Origin of Species.' Various cases of +colour correlated with constitutional peculiarities are given in my +'Variation of Animals and Plants under Domestication,' vol. ii. pp. 227, +335.) It has long been known that negroes, and even mulattoes, are almost +completely exempt from the yellow-fever, so destructive in tropical +America. (57. See, for instance, Nott and Gliddon, 'Types of Mankind,' p. +68.) They likewise escape to a large extent the fatal intermittent fevers, +that prevail along at least 2600 miles of the shores of Africa, and which +annually cause one-fifth of the white settlers to die, and another fifth to +return home invalided. (58. Major Tulloch, in a paper read before the +Statistical Society, April 20, 1840, and given in the 'Athenaeum,' 1840, p. +353.) This immunity in the negro seems to be partly inherent, depending on +some unknown peculiarity of constitution, and partly the result of +acclimatisation. Pouchet (59. 'The Plurality of the Human Race' +(translat.), 1864, p. 60.) states that the negro regiments recruited near +the Soudan, and borrowed from the Viceroy of Egypt for the Mexican war, +escaped the yellow-fever almost equally with the negroes originally brought +from various parts of Africa and accustomed to the climate of the West +Indies. That acclimatisation plays a part, is shewn by the many cases in +which negroes have become somewhat liable to tropical fevers, after having +resided for some time in a colder climate. (60. Quatrefages, 'Unité de +l'Espèce Humaine,' 1861, p. 205. Waitz, 'Introduction to Anthropology,' +translat., vol. i. 1863, p. 124. Livingstone gives analogous cases in his +'Travels.') The nature of the climate under which the white races have +long resided, likewise has some influence on them; for during the fearful +epidemic of yellow fever in Demerara during 1837, Dr. Blair found that the +death-rate of the immigrants was proportional to the latitude of the +country whence they had come. With the negro the immunity, as far as it is +the result of acclimatisation, implies exposure during a prodigious length +of time; for the aborigines of tropical America who have resided there from +time immemorial, are not exempt from yellow fever; and the Rev. H.B. +Tristram states, that there are districts in Northern Africa which the +native inhabitants are compelled annually to leave, though the negroes can +remain with safety. + +That the immunity of the negro is in any degree correlated with the colour +of his skin is a mere conjecture: it may be correlated with some +difference in his blood, nervous system, or other tissues. Nevertheless, +from the facts above alluded to, and from some connection apparently +existing between complexion and a tendency to consumption, the conjecture +seemed to me not improbable. Consequently I endeavoured, with but little +success (61. In the spring of 1862 I obtained permission from the +Director-General of the Medical department of the Army, to transmit to the +surgeons of the various regiments on foreign service a blank table, with +the following appended remarks, but I have received no returns. "As +several well-marked cases have been recorded with our domestic animals of a +relation between the colour of the dermal appendages and the constitution; +and it being notorious that there is some limited degree of relation +between the colour of the races of man and the climate inhabited by them; +the following investigation seems worth consideration. Namely, whether +there is any relation in Europeans between the colour of their hair, and +their liability to the diseases of tropical countries. If the surgeons of +the several regiments, when stationed in unhealthy tropical districts, +would be so good as first to count, as a standard of comparison, how many +men, in the force whence the sick are drawn, have dark and light-coloured +hair, and hair of intermediate or doubtful tints; and if a similar account +were kept by the same medical gentlemen, of all the men who suffered from +malarious and yellow fevers, or from dysentery, it would soon be apparent, +after some thousand cases had been tabulated, whether there exists any +relation between the colour of the hair and constitutional liability to +tropical diseases. Perhaps no such relation would be discovered, but the +investigation is well worth making. In case any positive result were +obtained, it might be of some practical use in selecting men for any +particular service. Theoretically the result would be of high interest, as +indicating one means by which a race of men inhabiting from a remote period +an unhealthy tropical climate, might have become dark-coloured by the +better preservation of dark-haired or dark-complexioned individuals during +a long succession of generations."), to ascertain how far it holds good. +The late Dr. Daniell, who had long lived on the West Coast of Africa, told +me that he did not believe in any such relation. He was himself unusually +fair, and had withstood the climate in a wonderful manner. When he first +arrived as a boy on the coast, an old and experienced negro chief predicted +from his appearance that this would prove the case. Dr. Nicholson, of +Antigua, after having attended to this subject, writes to me that dark- +coloured Europeans escape the yellow fever more than those that are light- +coloured. Mr. J.M. Harris altogether denies that Europeans with dark hair +withstand a hot climate better than other men: on the contrary, experience +has taught him in making a selection of men for service on the coast of +Africa, to choose those with red hair. (62. 'Anthropological Review,' +Jan. 1866, p. xxi. Dr. Sharpe also says, with respect to India ('Man a +Special Creation,' 1873, p. 118), "that it has been noticed by some medical +officers that Europeans with light hair and florid complexions suffer less +from diseases of tropical countries than persons with dark hair and sallow +complexions; and, so far as I know, there appear to be good grounds for +this remark." On the other hand, Mr. Heddle, of Sierra Leone, "who has had +more clerks killed under him than any other man," by the climate of the +West African Coast (W. Reade, 'African Sketch Book,' vol. ii. p. 522), +holds a directly opposite view, as does Capt. Burton.) As far, therefore, +as these slight indications go, there seems no foundation for the +hypothesis, that blackness has resulted from the darker and darker +individuals having survived better during long exposure to fever-generating +miasma. + +Dr. Sharpe remarks (63. 'Man a Special Creation,' 1873, p. 119.), that a +tropical sun, which burns and blisters a white skin, does not injure a +black one at all; and, as he adds, this is not due to habit in the +individual, for children only six or eight months old are often carried +about naked, and are not affected. I have been assured by a medical man, +that some years ago during each summer, but not during the winter, his +hands became marked with light brown patches, like, although larger than +freckles, and that these patches were never affected by sun-burning, whilst +the white parts of his skin have on several occasions been much inflamed +and blistered. With the lower animals there is, also, a constitutional +difference in liability to the action of the sun between those parts of the +skin clothed with white hair and other parts. (64. 'Variation of Animals +and Plants under Domestication,' vol. ii. pp. 336, 337.) Whether the +saving of the skin from being thus burnt is of sufficient importance to +account for a dark tint having been gradually acquired by man through +natural selection, I am unable to judge. If it be so, we should have to +assume that the natives of tropical America have lived there for a much +shorter time than the Negroes in Africa, or the Papuans in the southern +parts of the Malay archipelago, just as the lighter-coloured Hindoos have +resided in India for a shorter time than the darker aborigines of the +central and southern parts of the peninsula. + +Although with our present knowledge we cannot account for the differences +of colour in the races of man, through any advantage thus gained, or from +the direct action of climate; yet we must not quite ignore the latter +agency, for there is good reason to believe that some inherited effect is +thus produced. (65. See, for instance, Quatrefages ('Revue des Cours +Scientifiques,' Oct. 10, 1868, p. 724) on the effects of residence in +Abyssinia and Arabia, and other analogous cases. Dr. Rolle ('Der Mensch, +seine Abstammung,' etc., 1865, s. 99) states, on the authority of Khanikof, +that the greater number of German families settled in Georgia, have +acquired in the course of two generations dark hair and eyes. Mr. D. +Forbes informs me that the Quichuas in the Andes vary greatly in colour, +according to the position of the valleys inhabited by them.) + +We have seen in the second chapter that the conditions of life affect the +development of the bodily frame in a direct manner, and that the effects +are transmitted. Thus, as is generally admitted, the European settlers in +the United States undergo a slight but extraordinary rapid change of +appearance. Their bodies and limbs become elongated; and I hear from Col. +Bernys that during the late war in the United States, good evidence was +afforded of this fact by the ridiculous appearance presented by the German +regiments, when dressed in ready-made clothes manufactured for the American +market, and which were much too long for the men in every way. There is, +also, a considerable body of evidence shewing that in the Southern States +the house-slaves of the third generation present a markedly different +appearance from the field-slaves. (66. Harlan, 'Medical Researches,' p. +532. Quatrefages ('Unité de l'Espèce Humaine,' 1861, p. 128) has collected +much evidence on this head.) + +If, however, we look to the races of man as distributed over the world, we +must infer that their characteristic differences cannot be accounted for by +the direct action of different conditions of life, even after exposure to +them for an enormous period of time. The Esquimaux live exclusively on +animal food; they are clothed in thick fur, and are exposed to intense cold +and to prolonged darkness; yet they do not differ in any extreme degree +from the inhabitants of Southern China, who live entirely on vegetable +food, and are exposed almost naked to a hot, glaring climate. The +unclothed Fuegians live on the marine productions of their inhospitable +shores; the Botocudos of Brazil wander about the hot forests of the +interior and live chiefly on vegetable productions; yet these tribes +resemble each other so closely that the Fuegians on board the "Beagle" were +mistaken by some Brazilians for Botocudos. The Botocudos again, as well as +the other inhabitants of tropical America, are wholly different from the +Negroes who inhabit the opposite shores of the Atlantic, are exposed to a +nearly similar climate, and follow nearly the same habits of life. + +Nor can the differences between the races of man be accounted for by the +inherited effects of the increased or decreased use of parts, except to a +quite insignificant degree. Men who habitually live in canoes, may have +their legs somewhat stunted; those who inhabit lofty regions may have their +chests enlarged; and those who constantly use certain sense-organs may have +the cavities in which they are lodged somewhat increased in size, and their +features consequently a little modified. With civilised nations, the +reduced size of the jaws from lessened use--the habitual play of different +muscles serving to express different emotions--and the increased size of +the brain from greater intellectual activity, have together produced a +considerable effect on their general appearance when compared with savages. +(67. See Prof. Schaaffhausen, translat., in 'Anthropological Review,' Oct. +1868, p. 429.) Increased bodily stature, without any corresponding +increase in the size of the brain, may (judging from the previously adduced +case of rabbits), have given to some races an elongated skull of the +dolichocephalic type. + +Lastly, the little-understood principle of correlated development has +sometimes come into action, as in the case of great muscular development +and strongly projecting supra-orbital ridges. The colour of the skin and +hair are plainly correlated, as is the texture of the hair with its colour +in the Mandans of North America. (68. Mr. Catlin states ('N. American +Indians,' 3rd ed., 1842, vol. i. p. 49) that in the whole tribe of the +Mandans, about one in ten or twelve of the members, of all ages and both +sexes, have bright silvery grey hair, which is hereditary. Now this hair +is as coarse and harsh as that of a horse's mane, whilst the hair of other +colours is fine and soft.) The colour also of the skin, and the odour +emitted by it, are likewise in some manner connected. With the breeds of +sheep the number of hairs within a given space and the number of excretory +pores are related. (69. On the odour of the skin, Godron, 'Sur l'Espèce,' +tom. ii. p. 217. On the pores in the skin, Dr. Wilckens, 'Die Aufgaben der +Landwirth. Zootechnik,' 1869, s. 7.) If we may judge from the analogy of +our domesticated animals, many modifications of structure in man probably +come under this principle of correlated development. + +We have now seen that the external characteristic differences between the +races of man cannot be accounted for in a satisfactory manner by the direct +action of the conditions of life, nor by the effects of the continued use +of parts, nor through the principle of correlation. We are therefore led +to enquire whether slight individual differences, to which man is eminently +liable, may not have been preserved and augmented during a long series of +generations through natural selection. But here we are at once met by the +objection that beneficial variations alone can be thus preserved; and as +far as we are enabled to judge, although always liable to err on this head, +none of the differences between the races of man are of any direct or +special service to him. The intellectual and moral or social faculties +must of course be excepted from this remark. The great variability of all +the external differences between the races of man, likewise indicates that +they cannot be of much importance; for if important, they would long ago +have been either fixed and preserved, or eliminated. In this respect man +resembles those forms, called by naturalists protean or polymorphic, which +have remained extremely variable, owing, as it seems, to such variations +being of an indifferent nature, and to their having thus escaped the action +of natural selection. + +We have thus far been baffled in all our attempts to account for the +differences between the races of man; but there remains one important +agency, namely Sexual Selection, which appears to have acted powerfully on +man, as on many other animals. I do not intend to assert that sexual +selection will account for all the differences between the races. An +unexplained residuum is left, about which we can only say, in our +ignorance, that as individuals are continually born with, for instance, +heads a little rounder or narrower, and with noses a little longer or +shorter, such slight differences might become fixed and uniform, if the +unknown agencies which induced them were to act in a more constant manner, +aided by long-continued intercrossing. Such variations come under the +provisional class, alluded to in our second chapter, which for want of a +better term are often called spontaneous. Nor do I pretend that the +effects of sexual selection can be indicated with scientific precision; but +it can be shewn that it would be an inexplicable fact if man had not been +modified by this agency, which appears to have acted powerfully on +innumerable animals. It can further be shewn that the differences between +the races of man, as in colour, hairiness, form of features, etc., are of a +kind which might have been expected to come under the influence of sexual +selection. But in order to treat this subject properly, I have found it +necessary to pass the whole animal kingdom in review. I have therefore +devoted to it the Second Part of this work. At the close I shall return to +man, and, after attempting to shew how far he has been modified through +sexual selection, will give a brief summary of the chapters in this First +Part. + + +NOTE ON THE RESEMBLANCES AND DIFFERENCES IN THE STRUCTURE AND THE +DEVELOPMENT OF THE BRAIN IN MAN AND APES BY PROFESSOR HUXLEY, F.R.S. + +The controversy respecting the nature and the extent of the differences in +the structure of the brain in man and the apes, which arose some fifteen +years ago, has not yet come to an end, though the subject matter of the +dispute is, at present, totally different from what it was formerly. It +was originally asserted and re-asserted, with singular pertinacity, that +the brain of all the apes, even the highest, differs from that of man, in +the absence of such conspicuous structures as the posterior lobes of the +cerebral hemispheres, with the posterior cornu of the lateral ventricle and +the hippocampus minor, contained in those lobes, which are so obvious in +man. + +But the truth that the three structures in question are as well developed +in apes' as in human brains, or even better; and that it is characteristic +of all the Primates (if we exclude the Lemurs) to have these parts well +developed, stands at present on as secure a basis as any proposition in +comparative anatomy. Moreover, it is admitted by every one of the long +series of anatomists who, of late years, have paid special attention to the +arrangement of the complicated sulci and gyri which appear upon the surface +of the cerebral hemispheres in man and the higher apes, that they are +disposed after the very same pattern in him, as in them. Every principal +gyrus and sulcus of a chimpanzee's brain is clearly represented in that of +a man, so that the terminology which applies to the one answers for the +other. On this point there is no difference of opinion. Some years since, +Professor Bischoff published a memoir (70. 'Die Grosshirn-Windungen des +Menschen;' 'Abhandlungen der K. Bayerischen Akademie,' B. x. 1868.) on the +cerebral convolutions of man and apes; and as the purpose of my learned +colleague was certainly not to diminish the value of the differences +between apes and men in this respect, I am glad to make a citation from +him. + +"That the apes, and especially the orang, chimpanzee and gorilla, come very +close to man in their organisation, much nearer than to any other animal, +is a well known fact, disputed by nobody. Looking at the matter from the +point of view of organisation alone, no one probably would ever have +disputed the view of Linnaeus, that man should be placed, merely as a +peculiar species, at the head of the mammalia and of those apes. Both +shew, in all their organs, so close an affinity, that the most exact +anatomical investigation is needed in order to demonstrate those +differences which really exist. So it is with the brains. The brains of +man, the orang, the chimpanzee, the gorilla, in spite of all the important +differences which they present, come very close to one another" (loc. cit. +p. 101). + +There remains, then, no dispute as to the resemblance in fundamental +characters, between the ape's brain and man's: nor any as to the +wonderfully close similarity between the chimpanzee, orang and man, in even +the details of the arrangement of the gyri and sulci of the cerebral +hemispheres. Nor, turning to the differences between the brains of the +highest apes and that of man, is there any serious question as to the +nature and extent of these differences. It is admitted that the man's +cerebral hemispheres are absolutely and relatively larger than those of the +orang and chimpanzee; that his frontal lobes are less excavated by the +upward protrusion of the roof of the orbits; that his gyri and sulci are, +as a rule, less symmetrically disposed, and present a greater number of +secondary plications. And it is admitted that, as a rule, in man, the +temporo-occipital or "external perpendicular" fissure, which is usually so +strongly marked a feature of the ape's brain is but faintly marked. But it +is also clear, that none of these differences constitutes a sharp +demarcation between the man's and the ape's brain. In respect to the +external perpendicular fissure of Gratiolet, in the human brain for +instance, Professor Turner remarks: (71. 'Convolutions of the Human +Cerebrum Topographically Considered,' 1866, p. 12.) + +"In some brains it appears simply as an indentation of the margin of the +hemisphere, but, in others, it extends for some distance more or less +transversely outwards. I saw it in the right hemisphere of a female brain +pass more than two inches outwards; and on another specimen, also the right +hemisphere, it proceeded for four-tenths of an inch outwards, and then +extended downwards, as far as the lower margin of the outer surface of the +hemisphere. The imperfect definition of this fissure in the majority of +human brains, as compared with its remarkable distinctness in the brain of +most Quadrumana, is owing to the presence, in the former, of certain +superficial, well marked, secondary convolutions which bridge it over and +connect the parietal with the occipital lobe. The closer the first of +these bridging gyri lies to the longitudinal fissure, the shorter is the +external parieto-occipital fissure" (loc. cit. p. 12). + +The obliteration of the external perpendicular fissure of Gratiolet, +therefore, is not a constant character of the human brain. On the other +hand, its full development is not a constant character of the higher ape's +brain. For, in the chimpanzee, the more or less extensive obliteration of +the external perpendicular sulcus by "bridging convolutions," on one side +or the other, has been noted over and over again by Prof. Rolleston, Mr. +Marshall, M. Broca and Professor Turner. At the conclusion of a special +paper on this subject the latter writes: (72. Notes more especially on +the bridging convolutions in the Brain of the Chimpanzee, 'Proceedings of +the Royal Society of Edinburgh,' 1865-6.) + +"The three specimens of the brain of a chimpanzee, just described, prove, +that the generalisation which Gratiolet has attempted to draw of the +complete absence of the first connecting convolution and the concealment of +the second, as essentially characteristic features in the brain of this +animal, is by no means universally applicable. In only one specimen did +the brain, in these particulars, follow the law which Gratiolet has +expressed. As regards the presence of the superior bridging convolution, I +am inclined to think that it has existed in one hemisphere, at least, in a +majority of the brains of this animal which have, up to this time, been +figured or described. The superficial position of the second bridging +convolution is evidently less frequent, and has as yet, I believe, only +been seen in the brain (A) recorded in this communication. The +asymmetrical arrangement in the convolutions of the two hemispheres, which +previous observers have referred to in their descriptions, is also well +illustrated in these specimens" (pp. 8, 9). + +Even were the presence of the temporo-occipital, or external perpendicular, +sulcus, a mark of distinction between the higher apes and man, the value of +such a distinctive character would be rendered very doubtful by the +structure of the brain in the Platyrrhine apes. In fact, while the +temporo-occipital is one of the most constant of sulci in the Catarrhine, +or Old World, apes, it is never very strongly developed in the New World +apes; it is absent in the smaller Platyrrhini; rudimentary in Pithecia (73. +Flower, 'On the Anatomy of Pithecia Monachus,' 'Proceedings of the +Zoological Society,' 1862.); and more or less obliterated by bridging +convolutions in Ateles. + +A character which is thus variable within the limits of a single group can +have no great taxonomic value. + +It is further established, that the degree of asymmetry of the convolution +of the two sides in the human brain is subject to much individual +variation; and that, in those individuals of the Bushman race who have been +examined, the gyri and sulci of the two hemispheres are considerably less +complicated and more symmetrical than in the European brain, while, in some +individuals of the chimpanzee, their complexity and asymmetry become +notable. This is particularly the case in the brain of a young male +chimpanzee figured by M. Broca. ('L'ordre des Primates,' p. 165, fig. 11.) + +Again, as respects the question of absolute size, it is established that +the difference between the largest and the smallest healthy human brain is +greater than the difference between the smallest healthy human brain and +the largest chimpanzee's or orang's brain. + +Moreover, there is one circumstance in which the orang's and chimpanzee's +brains resemble man's, but in which they differ from the lower apes, and +that is the presence of two corpora candicantia--the Cynomorpha having but +one. + +In view of these facts I do not hesitate in this year 1874, to repeat and +insist upon the proposition which I enunciated in 1863: (74. 'Man's Place +in Nature,' p. 102.) + +"So far as cerebral structure goes, therefore, it is clear that man differs +less from the chimpanzee or the orang, than these do even from the monkeys, +and that the difference between the brain of the chimpanzee and of man is +almost insignificant when compared with that between the chimpanzee brain +and that of a Lemur." + +In the paper to which I have referred, Professor Bischoff does not deny the +second part of this statement, but he first makes the irrelevant remark +that it is not wonderful if the brains of an orang and a Lemur are very +different; and secondly, goes on to assert that, "If we successively +compare the brain of a man with that of an orang; the brain of this with +that of a chimpanzee; of this with that of a gorilla, and so on of a +Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus, +Callithrix, Lemur, Stenops, Hapale, we shall not meet with a greater, or +even as great a, break in the degree of development of the convolutions, as +we find between the brain of a man and that of an orang or chimpanzee." + +To which I reply, firstly, that whether this assertion be true or false, it +has nothing whatever to do with the proposition enunciated in 'Man's Place +in Nature,' which refers not to the development of the convolutions alone, +but to the structure of the whole brain. If Professor Bischoff had taken +the trouble to refer to p. 96 of the work he criticises, in fact, he would +have found the following passage: "And it is a remarkable circumstance +that though, so far as our present knowledge extends, there IS one true +structural break in the series of forms of Simian brains, this hiatus does +not lie between man and the manlike apes, but between the lower and the +lowest Simians, or in other words, between the Old and New World apes and +monkeys and the Lemurs. Every Lemur which has yet been examined, in fact, +has its cerebellum partially visible from above; and its posterior lobe, +with the contained posterior cornu and hippocampus minor, more or less +rudimentary. Every marmoset, American monkey, Old World monkey, baboon or +manlike ape, on the contrary, has its cerebellum entirely hidden, +posteriorly, by the cerebral lobes, and possesses a large posterior cornu +with a well-developed hippocampus minor." + +This statement was a strictly accurate account of what was known when it +was made; and it does not appear to me to be more than apparently weakened +by the subsequent discovery of the relatively small development of the +posterior lobes in the Siamang and in the Howling monkey. Notwithstanding +the exceptional brevity of the posterior lobes in these two species, no one +will pretend that their brains, in the slightest degree, approach those of +the Lemurs. And if, instead of putting Hapale out of its natural place, as +Professor Bischoff most unaccountably does, we write the series of animals +he has chosen to mention as follows: Homo, Pithecus, Troglodytes, +Hylobates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus, +Callithrix, Hapale, Lemur, Stenops, I venture to reaffirm that the great +break in this series lies between Hapale and Lemur, and that this break is +considerably greater than that between any other two terms of that series. +Professor Bischoff ignores the fact that long before he wrote, Gratiolet +had suggested the separation of the Lemurs from the other Primates on the +very ground of the difference in their cerebral characters; and that +Professor Flower had made the following observations in the course of his +description of the brain of the Javan Loris: (75. 'Transactions of the +Zoological Society,' vol. v. 1862.) + +"And it is especially remarkable that, in the development of the posterior +lobes, there is no approximation to the Lemurine, short hemisphered brain, +in those monkeys which are commonly supposed to approach this family in +other respects, viz. the lower members of the Platyrrhine group." + +So far as the structure of the adult brain is concerned, then, the very +considerable additions to our knowledge, which have been made by the +researches of so many investigators, during the past ten years, fully +justify the statement which I made in 1863. But it has been said, that, +admitting the similarity between the adult brains of man and apes, they are +nevertheless, in reality, widely different, because they exhibit +fundamental differences in the mode of their development. No one would be +more ready than I to admit the force of this argument, if such fundamental +differences of development really exist. But I deny that they do exist. +On the contrary, there is a fundamental agreement in the development of the +brain in men and apes. + +Gratiolet originated the statement that there is a fundamental difference +in the development of the brains of apes and that of man--consisting in +this; that, in the apes, the sulci which first make their appearance are +situated on the posterior region of the cerebral hemispheres, while, in the +human foetus, the sulci first become visible on the frontal lobes. (76. +Chez tous les singes, les plis postérieurs se developpent les premiers; +les plis antérieurs se developpent plus tard, aussi la vertèbre occipitale +et la parietale sont-elles relativement tres-grandes chez le foetus. +L'Homme présente une exception remarquable quant a l'époque de l'apparition +des plis frontaux, qui sont les premiers indiqués; mais le développement +general du lobe frontal, envisagé seulement par rapport a son volume, suit +les mêmes lois que dans les singes: Gratiolet, 'Mémoire sur les plis +cérèbres de l'Homme et des Primateaux,' p. 39, Tab. iv, fig. 3.) + +This general statement is based upon two observations, the one of a Gibbon +almost ready to be born, in which the posterior gyri were "well developed," +while those of the frontal lobes were "hardly indicated" (77. Gratiolet's +words are (loc. cit. p. 39): "Dans le foetus dont il s'agit les plis +cérébraux posterieurs sont bien developpés, tandis que les plis du lobe +frontal sont a peine indiqués." The figure, however (Pl. iv, fig. 3), +shews the fissure of Rolando, and one of the frontal sulci plainly enough. +Nevertheless, M. Alix, in his 'Notice sur les travaux anthropologiques de +Gratiolet' ('Mem. de la Societé d'Anthropologie de Paris,' 1868, page 32), +writes thus: "Gratiolet a eu entre les mains le cerveau d'un foetus de +Gibbon, singe eminemment supérieur, et tellement rapproché de l'orang, que +des naturalistes tres-compétents l'ont rangé parmi les anthropoides. M. +Huxley, par exemple, n'hesite pas sur ce point. Eh bien, c'est sur le +cerveau d'un foetus de Gibbon que Gratiolet a vu LES CIRCONVOLUTIONS DU +LOBE TEMPORO-SPHENOIDAL DÉJÀ DEVELOPPÉES LORSQU'IL N'EXISTENT PAS ENCORE DE +PLIS SUR LE LOBE FRONTAL. Il etait donc bien autorisé a dire que, chez +l'homme les circonvolutions apparaissent d'a en w, tandis que chez les +singes elles se developpent d'w en a."), and the other of a human foetus at +the 22nd or 23rd week of uterogestation, in which Gratiolet notes that the +insula was uncovered, but that nevertheless "des incisures sement de lobe +anterieur, une scissure peu profonde indique la separation du lobe +occipital, tres-reduit, d'ailleurs dès cette époque. Le reste de la +surface cérébrale est encore absolument lisse." + +Three views of this brain are given in Plate II, figs. 1, 2, 3, of the work +cited, shewing the upper, lateral and inferior views of the hemispheres, +but not the inner view. It is worthy of note that the figure by no means +bears out Gratiolet's description, inasmuch as the fissure (antero- +temporal) on the posterior half of the face of the hemisphere is more +marked than any of those vaguely indicated in the anterior half. If the +figure is correct, it in no way justifies Gratiolet's conclusion: "Il y a +donc entre ces cerveaux [those of a Callithrix and of a Gibbon] et celui du +foetus humain une différence fondamental. Chez celui-ci, longtemps avant +que les plis temporaux apparaissent, les plis frontaux, ESSAYENT +d'exister." + +Since Gratiolet's time, however, the development of the gyri and sulci of +the brain has been made the subject of renewed investigation by Schmidt, +Bischoff, Pansch (78. 'Ueber die typische Anordnung der Furchen und +Windungen auf den Grosshirn-Hemisphären des Menschen und der Affen,' +'Archiv für Anthropologie,' iii. 1868.), and more particularly by Ecker +(79. 'Zur Entwicklungs Geschichte der Furchen und Windungen der Grosshirn- +Hemisphären im Foetus des Menschen,' 'Archiv für Anthropologie,' iii. +1868.), whose work is not only the latest, but by far the most complete, +memoir on the subject. + +The final results of their inquiries may be summed up as follows:-- + +1. In the human foetus, the sylvian fissure is formed in the course of the +third month of uterogestation. In this, and in the fourth month, the +cerebral hemispheres are smooth and rounded (with the exception of the +sylvian depression), and they project backwards far beyond the cerebellum. + +2. The sulci, properly so called, begin to appear in the interval between +the end of the fourth and the beginning of the sixth month of foetal life, +but Ecker is careful to point out that, not only the time, but the order, +of their appearance is subject to considerable individual variation. In no +case, however, are either the frontal or the temporal sulci the earliest. + +The first which appears, in fact, lies on the inner face of the hemisphere +(whence doubtless Gratiolet, who does not seem to have examined that face +in his foetus, overlooked it), and is either the internal perpendicular +(occipito-parietal), or the calcarine sulcus, these two being close +together and eventually running into one another. As a rule the occipito- +parietal is the earlier of the two. + +3. At the latter part of this period, another sulcus, the "posterio- +parietal," or "Fissure of Rolando" is developed, and it is followed, in the +course of the sixth month, by the other principal sulci of the frontal, +parietal, temporal and occipital lobes. There is, however, no clear +evidence that one of these constantly appears before the other; and it is +remarkable that, in the brain at the period described and figured by Ecker +(loc. cit. pp. 212-213, Taf. II, figs. 1, 2, 3, 4), the antero-temporal +sulcus (scissure parallele) so characteristic of the ape's brain, is as +well, if not better developed than the fissure of Rolando, and is much more +marked than the proper frontal sulci. + +Taking the facts as they now stand, it appears to me that the order of the +appearance of the sulci and gyri in the foetal human brain is in perfect +harmony with the general doctrine of evolution, and with the view that man +has been evolved from some ape-like form; though there can be no doubt that +form was, in many respects, different from any member of the Primates now +living. + +Von Baer taught us, half a century ago, that, in the course of their +development, allied animals put on at first, the characters of the greater +groups to which they belong, and, by degrees, assume those which restrict +them within the limits of their family, genus, and species; and he proved, +at the same time, that no developmental stage of a higher animal is +precisely similar to the adult condition of any lower animal. It is quite +correct to say that a frog passes through the condition of a fish, inasmuch +as at one period of its life the tadpole has all the characters of a fish, +and if it went no further, would have to be grouped among fishes. But it +is equally true that a tadpole is very different from any known fish. + +In like manner, the brain of a human foetus, at the fifth month, may +correctly be said to be, not only the brain of an ape, but that of an +Arctopithecine or marmoset-like ape; for its hemispheres, with their great +posterior lobster, and with no sulci but the sylvian and the calcarine, +present the characteristics found only in the group of the Arctopithecine +Primates. But it is equally true, as Gratiolet remarks, that, in its +widely open sylvian fissure, it differs from the brain of any actual +marmoset. No doubt it would be much more similar to the brain of an +advanced foetus of a marmoset. But we know nothing whatever of the +development of the brain in the marmosets. In the Platyrrhini proper, the +only observation with which I am acquainted is due to Pansch, who found in +the brain of a foetal Cebus Apella, in addition to the sylvian fissure and +the deep calcarine fissure, only a very shallow antero-temporal fissure +(scissure parallele of Gratiolet). + +Now this fact, taken together with the circumstance that the antero- +temporal sulcus is present in such Platyrrhini as the Saimiri, which +present mere traces of sulci on the anterior half of the exterior of the +cerebral hemispheres, or none at all, undoubtedly, so far as it goes, +affords fair evidence in favour of Gratiolet's hypothesis, that the +posterior sulci appear before the anterior, in the brains of the +Platyrrhini. But, it by no means follows, that the rule which may hold +good for the Platyrrhini extends to the Catarrhini. We have no information +whatever respecting the development of the brain in the Cynomorpha; and, as +regards the Anthropomorpha, nothing but the account of the brain of the +Gibbon, near birth, already referred to. At the present moment there is +not a shadow of evidence to shew that the sulci of a chimpanzee's, or +orang's, brain do not appear in the same order as a man's. + +Gratiolet opens his preface with the aphorism: "Il est dangereux dans les +sciences de conclure trop vite." I fear he must have forgotten this sound +maxim by the time he had reached the discussion of the differences between +men and apes, in the body of his work. No doubt, the excellent author of +one of the most remarkable contributions to the just understanding of the +mammalian brain which has ever been made, would have been the first to +admit the insufficiency of his data had he lived to profit by the advance +of inquiry. The misfortune is that his conclusions have been employed by +persons incompetent to appreciate their foundation, as arguments in favour +of obscurantism. (80. For example, M. l'Abbe Lecomte in his terrible +pamphlet, 'Le Darwinisme et l'origine de l'Homme,' 1873.) + +But it is important to remark that, whether Gratiolet was right or wrong in +his hypothesis respecting the relative order of appearance of the temporal +and frontal sulci, the fact remains; that before either temporal or frontal +sulci, appear, the foetal brain of man presents characters which are found +only in the lowest group of the Primates (leaving out the Lemurs); and that +this is exactly what we should expect to be the case, if man has resulted +from the gradual modification of the same form as that from which the other +Primates have sprung. + + + +PART II. SEXUAL SELECTION. + + +CHAPTER VIII. + +PRINCIPLES OF SEXUAL SELECTION. + +Secondary sexual characters--Sexual selection--Manner of action--Excess of +males--Polygamy--The male alone generally modified through sexual +selection--Eagerness of the male--Variability of the male--Choice exerted +by the female--Sexual compared with natural selection--Inheritance, at +corresponding periods of life, at corresponding seasons of the year, and as +limited by sex--Relations between the several forms of inheritance--Causes +why one sex and the young are not modified through sexual selection-- +Supplement on the proportional numbers of the two sexes throughout the +animal kingdom--The proportion of the sexes in relation to natural +selection. + +With animals which have their sexes separated, the males necessarily differ +from the females in their organs of reproduction; and these are the primary +sexual characters. But the sexes often differ in what Hunter has called +secondary sexual characters, which are not directly connected with the act +of reproduction; for instance, the male possesses certain organs of sense +or locomotion, of which the female is quite destitute, or has them more +highly-developed, in order that he may readily find or reach her; or again +the male has special organs of prehension for holding her securely. These +latter organs, of infinitely diversified kinds, graduate into those which +are commonly ranked as primary, and in some cases can hardly be +distinguished from them; we see instances of this in the complex appendages +at the apex of the abdomen in male insects. Unless indeed we confine the +term "primary" to the reproductive glands, it is scarcely possible to +decide which ought to be called primary and which secondary. + +The female often differs from the male in having organs for the nourishment +or protection of her young, such as the mammary glands of mammals, and the +abdominal sacks of the marsupials. In some few cases also the male +possesses similar organs, which are wanting in the female, such as the +receptacles for the ova in certain male fishes, and those temporarily +developed in certain male frogs. The females of most bees are provided +with a special apparatus for collecting and carrying pollen, and their +ovipositor is modified into a sting for the defence of the larvae and the +community. Many similar cases could be given, but they do not here concern +us. There are, however, other sexual differences quite unconnected with +the primary reproductive organs, and it is with these that we are more +especially concerned--such as the greater size, strength, and pugnacity of +the male, his weapons of offence or means of defence against rivals, his +gaudy colouring and various ornaments, his power of song, and other such +characters. + +Besides the primary and secondary sexual differences, such as the +foregoing, the males and females of some animals differ in structures +related to different habits of life, and not at all, or only indirectly, to +the reproductive functions. Thus the females of certain flies (Culicidae +and Tabanidae) are blood-suckers, whilst the males, living on flowers, have +mouths destitute of mandibles. (1. Westwood, 'Modern Classification of +Insects,' vol. ii. 1840, p. 541. For the statement about Tanais, mentioned +below, I am indebted to Fritz Muller.) The males of certain moths and of +some crustaceans (e.g. Tanais) have imperfect, closed mouths, and cannot +feed. The complemental males of certain Cirripedes live like epiphytic +plants either on the female or the hermaphrodite form, and are destitute of +a mouth and of prehensile limbs. In these cases it is the male which has +been modified, and has lost certain important organs, which the females +possess. In other cases it is the female which has lost such parts; for +instance, the female glow-worm is destitute of wings, as also are many +female moths, some of which never leave their cocoons. Many female +parasitic crustaceans have lost their natatory legs. In some weevil- +beetles (Curculionidae) there is a great difference between the male and +female in the length of the rostrum or snout (2. Kirby and Spence, +'Introduction to Entomology,' vol. iii. 1826, p. 309.); but the meaning of +this and of many analogous differences, is not at all understood. +Differences of structure between the two sexes in relation to different +habits of life are generally confined to the lower animals; but with some +few birds the beak of the male differs from that of the female. In the +Huia of New Zealand the difference is wonderfully great, and we hear from +Dr. Buller (3. 'Birds of New Zealand,' 1872, p. 66.) that the male uses +his strong beak in chiselling the larvae of insects out of decayed wood, +whilst the female probes the softer parts with her far longer, much curved +and pliant beak: and thus they mutually aid each other. In most cases, +differences of structure between the sexes are more or less directly +connected with the propagation of the species: thus a female, which has to +nourish a multitude of ova, requires more food than the male, and +consequently requires special means for procuring it. A male animal, which +lives for a very short time, might lose its organs for procuring food +through disuse, without detriment; but he would retain his locomotive +organs in a perfect state, so that he might reach the female. The female, +on the other hand, might safely lose her organs for flying, swimming, or +walking, if she gradually acquired habits which rendered such powers +useless. + +We are, however, here concerned only with sexual selection. This depends +on the advantage which certain individuals have over others of the same sex +and species solely in respect of reproduction. When, as in the cases above +mentioned, the two sexes differ in structure in relation to different +habits of life, they have no doubt been modified through natural selection, +and by inheritance limited to one and the same sex. So again the primary +sexual organs, and those for nourishing or protecting the young, come under +the same influence; for those individuals which generated or nourished +their offspring best, would leave, ceteris paribus, the greatest number to +inherit their superiority; whilst those which generated or nourished their +offspring badly, would leave but few to inherit their weaker powers. As +the male has to find the female, he requires organs of sense and +locomotion, but if these organs are necessary for the other purposes of +life, as is generally the case, they will have been developed through +natural selection. When the male has found the female, he sometimes +absolutely requires prehensile organs to hold her; thus Dr. Wallace informs +me that the males of certain moths cannot unite with the females if their +tarsi or feet are broken. The males of many oceanic crustaceans, when +adult, have their legs and antennae modified in an extraordinary manner for +the prehension of the female; hence we may suspect that it is because these +animals are washed about by the waves of the open sea, that they require +these organs in order to propagate their kind, and if so, their development +has been the result of ordinary or natural selection. Some animals +extremely low in the scale have been modified for this same purpose; thus +the males of certain parasitic worms, when fully grown, have the lower +surface of the terminal part of their bodies roughened like a rasp, and +with this they coil round and permanently hold the females. (4. M. +Perrier advances this case ('Revue Scientifique,' Feb. 1, 1873, p. 865) as +one fatal to the belief in sexual election, inasmuch as he supposes that I +attribute all the differences between the sexes to sexual selection. This +distinguished naturalist, therefore, like so many other Frenchmen, has not +taken the trouble to understand even the first principles of sexual +selection. An English naturalist insists that the claspers of certain male +animals could not have been developed through the choice of the female! +Had I not met with this remark, I should not have thought it possible for +any one to have read this chapter and to have imagined that I maintain that +the choice of the female had anything to do with the development of the +prehensile organs in the male.) + +When the two sexes follow exactly the same habits of life, and the male has +the sensory or locomotive organs more highly developed than those of the +female, it may be that the perfection of these is indispensable to the male +for finding the female; but in the vast majority of cases, they serve only +to give one male an advantage over another, for with sufficient time, the +less well-endowed males would succeed in pairing with the females; and +judging from the structure of the female, they would be in all other +respects equally well adapted for their ordinary habits of life. Since in +such cases the males have acquired their present structure, not from being +better fitted to survive in the struggle for existence, but from having +gained an advantage over other males, and from having transmitted this +advantage to their male offspring alone, sexual selection must here have +come into action. It was the importance of this distinction which led me +to designate this form of selection as Sexual Selection. So again, if the +chief service rendered to the male by his prehensile organs is to prevent +the escape of the female before the arrival of other males, or when +assaulted by them, these organs will have been perfected through sexual +selection, that is by the advantage acquired by certain individuals over +their rivals. But in most cases of this kind it is impossible to +distinguish between the effects of natural and sexual selection. Whole +chapters could be filled with details on the differences between the sexes +in their sensory, locomotive, and prehensile organs. As, however, these +structures are not more interesting than others adapted for the ordinary +purposes of life I shall pass them over almost entirely, giving only a few +instances under each class. + +There are many other structures and instincts which must have been +developed through sexual selection--such as the weapons of offence and the +means of defence of the males for fighting with and driving away their +rivals--their courage and pugnacity--their various ornaments--their +contrivances for producing vocal or instrumental music--and their glands +for emitting odours, most of these latter structures serving only to allure +or excite the female. It is clear that these characters are the result of +sexual and not of ordinary selection, since unarmed, unornamented, or +unattractive males would succeed equally well in the battle for life and in +leaving a numerous progeny, but for the presence of better endowed males. +We may infer that this would be the case, because the females, which are +unarmed and unornamented, are able to survive and procreate their kind. +Secondary sexual characters of the kind just referred to, will be fully +discussed in the following chapters, as being in many respects interesting, +but especially as depending on the will, choice, and rivalry of the +individuals of either sex. When we behold two males fighting for the +possession of the female, or several male birds displaying their gorgeous +plumage, and performing strange antics before an assembled body of females, +we cannot doubt that, though led by instinct, they know what they are +about, and consciously exert their mental and bodily powers. + +Just as man can improve the breeds of his game-cocks by the selection of +those birds which are victorious in the cockpit, so it appears that the +strongest and most vigorous males, or those provided with the best weapons, +have prevailed under nature, and have led to the improvement of the natural +breed or species. A slight degree of variability leading to some +advantage, however slight, in reiterated deadly contests would suffice for +the work of sexual selection; and it is certain that secondary sexual +characters are eminently variable. Just as man can give beauty, according +to his standard of taste, to his male poultry, or more strictly can modify +the beauty originally acquired by the parent species, can give to the +Sebright bantam a new and elegant plumage, an erect and peculiar carriage-- +so it appears that female birds in a state of nature, have by a long +selection of the more attractive males, added to their beauty or other +attractive qualities. No doubt this implies powers of discrimination and +taste on the part of the female which will at first appear extremely +improbable; but by the facts to be adduced hereafter, I hope to be able to +shew that the females actually have these powers. When, however, it is +said that the lower animals have a sense of beauty, it must not be supposed +that such sense is comparable with that of a cultivated man, with his +multiform and complex associated ideas. A more just comparison would be +between the taste for the beautiful in animals, and that in the lowest +savages, who admire and deck themselves with any brilliant, glittering, or +curious object. + +From our ignorance on several points, the precise manner in which sexual +selection acts is somewhat uncertain. Nevertheless if those naturalists +who already believe in the mutability of species, will read the following +chapters, they will, I think, agree with me, that sexual selection has +played an important part in the history of the organic world. It is +certain that amongst almost all animals there is a struggle between the +males for the possession of the female. This fact is so notorious that it +would be superfluous to give instances. Hence the females have the +opportunity of selecting one out of several males, on the supposition that +their mental capacity suffices for the exertion of a choice. In many cases +special circumstances tend to make the struggle between the males +particularly severe. Thus the males of our migratory birds generally +arrive at their places of breeding before the females, so that many males +are ready to contend for each female. I am informed by Mr. Jenner Weir, +that the bird-catchers assert that this is invariably the case with the +nightingale and blackcap, and with respect to the latter he can himself +confirm the statement. + +Mr. Swaysland of Brighton has been in the habit, during the last forty +years, of catching our migratory birds on their first arrival, and he has +never known the females of any species to arrive before their males. +During one spring he shot thirty-nine males of Ray's wagtail (Budytes Raii) +before he saw a single female. Mr. Gould has ascertained by the dissection +of those snipes which arrive the first in this country, that the males come +before the females. And the like holds good with most of the migratory +birds of the United States. (5. J.A. Allen, on the 'Mammals and Winter +Birds of Florida,' Bulletin of Comparative Zoology, Harvard College, p. +268.) The majority of the male salmon in our rivers, on coming up from the +sea, are ready to breed before the females. So it appears to be with frogs +and toads. Throughout the great class of insects the males almost always +are the first to emerge from the pupal state, so that they generally abound +for a time before any females can be seen. (6. Even with those plants in +which the sexes are separate, the male flowers are generally mature before +the female. As first shewn by C.K. Sprengel, many hermaphrodite plants are +dichogamous; that is, their male and female organs are not ready at the +same time, so that they cannot be self-fertilised. Now in such flowers, +the pollen is in general matured before the stigma, though there are +exceptional cases in which the female organs are beforehand.) The cause of +this difference between the males and females in their periods of arrival +and maturity is sufficiently obvious. Those males which annually first +migrated into any country, or which in the spring were first ready to +breed, or were the most eager, would leave the largest number of offspring; +and these would tend to inherit similar instincts and constitutions. It +must be borne in mind that it would have been impossible to change very +materially the time of sexual maturity in the females, without at the same +time interfering with the period of the production of the young--a period +which must be determined by the seasons of the year. On the whole there +can be no doubt that with almost all animals, in which the sexes are +separate, there is a constantly recurrent struggle between the males for +the possession of the females. + +Our difficulty in regard to sexual selection lies in understanding how it +is that the males which conquer other males, or those which prove the most +attractive to the females, leave a greater number of offspring to inherit +their superiority than their beaten and less attractive rivals. Unless +this result does follow, the characters which give to certain males an +advantage over others, could not be perfected and augmented through sexual +selection. When the sexes exist in exactly equal numbers, the worst- +endowed males will (except where polygamy prevails), ultimately find +females, and leave as many offspring, as well fitted for their general +habits of life, as the best-endowed males. From various facts and +considerations, I formerly inferred that with most animals, in which +secondary sexual characters are well developed, the males considerably +exceeded the females in number; but this is not by any means always true. +If the males were to the females as two to one, or as three to two, or even +in a somewhat lower ratio, the whole affair would be simple; for the +better-armed or more attractive males would leave the largest number of +offspring. But after investigating, as far as possible, the numerical +proportion of the sexes, I do not believe that any great inequality in +number commonly exists. In most cases sexual selection appears to have +been effective in the following manner. + +Let us take any species, a bird for instance, and divide the females +inhabiting a district into two equal bodies, the one consisting of the more +vigorous and better-nourished individuals, and the other of the less +vigorous and healthy. The former, there can be little doubt, would be +ready to breed in the spring before the others; and this is the opinion of +Mr. Jenner Weir, who has carefully attended to the habits of birds during +many years. There can also be no doubt that the most vigorous, best- +nourished and earliest breeders would on an average succeed in rearing the +largest number of fine offspring. (7. Here is excellent evidence on the +character of the offspring from an experienced ornithologist. Mr. J.A. +Allen, in speaking ('Mammals and Winter Birds of E. Florida,' p. 229) of +the later broods, after the accidental destruction of the first, says, that +these "are found to be smaller and paler-coloured than those hatched +earlier in the season. In cases where several broods are reared each year, +as a general rule the birds of the earlier broods seem in all respects the +most perfect and vigorous.") The males, as we have seen, are generally +ready to breed before the females; the strongest, and with some species the +best armed of the males, drive away the weaker; and the former would then +unite with the more vigorous and better-nourished females, because they are +the first to breed. (8. Hermann Müller has come to this same conclusion +with respect to those female bees which are the first to emerge from the +pupa each year. See his remarkable essay, 'Anwendung der Darwin'schen +Lehre auf Bienen,' 'Verh. d. V. Jahrg.' xxix. p. 45.) Such vigorous pairs +would surely rear a larger number of offspring than the retarded females, +which would be compelled to unite with the conquered and less powerful +males, supposing the sexes to be numerically equal; and this is all that is +wanted to add, in the course of successive generations, to the size, +strength and courage of the males, or to improve their weapons. + +But in very many cases the males which conquer their rivals, do not obtain +possession of the females, independently of the choice of the latter. The +courtship of animals is by no means so simple and short an affair as might +be thought. The females are most excited by, or prefer pairing with, the +more ornamented males, or those which are the best songsters, or play the +best antics; but it is obviously probable that they would at the same time +prefer the more vigorous and lively males, and this has in some cases been +confirmed by actual observation. (9. With respect to poultry, I have +received information, hereafter to be given, to this effect. Even birds, +such as pigeons, which pair for life, the female, as I hear from Mr. Jenner +Weir, will desert her mate if he is injured or grows weak.) Thus the more +vigorous females, which are the first to breed, will have the choice of +many males; and though they may not always select the strongest or best +armed, they will select those which are vigorous and well armed, and in +other respects the most attractive. Both sexes, therefore, of such early +pairs would as above explained, have an advantage over others in rearing +offspring; and this apparently has sufficed during a long course of +generations to add not only to the strength and fighting powers of the +males, but likewise to their various ornaments or other attractions. + +In the converse and much rarer case of the males selecting particular +females, it is plain that those which were the most vigorous and had +conquered others, would have the freest choice; and it is almost certain +that they would select vigorous as well as attractive females. Such pairs +would have an advantage in rearing offspring, more especially if the male +had the power to defend the female during the pairing-season as occurs with +some of the higher animals, or aided her in providing for the young. The +same principles would apply if each sex preferred and selected certain +individuals of the opposite sex; supposing that they selected not only the +more attractive, but likewise the more vigorous individuals. + +NUMERICAL PROPORTION OF THE TWO SEXES. + +I have remarked that sexual selection would be a simple affair if the males +were considerably more numerous than the females. Hence I was led to +investigate, as far as I could, the proportions between the two sexes of as +many animals as possible; but the materials are scanty. I will here give +only a brief abstract of the results, retaining the details for a +supplementary discussion, so as not to interfere with the course of my +argument. Domesticated animals alone afford the means of ascertaining the +proportional numbers at birth; but no records have been specially kept for +this purpose. By indirect means, however, I have collected a considerable +body of statistics, from which it appears that with most of our domestic +animals the sexes are nearly equal at birth. Thus 25,560 births of race- +horses have been recorded during twenty-one years, and the male births were +to the female births as 99.7 to 100. In greyhounds the inequality is +greater than with any other animal, for out of 6878 births during twelve +years, the male births were to the female as 110.1 to 100. It is, however, +in some degree doubtful whether it is safe to infer that the proportion +would be the same under natural conditions as under domestication; for +slight and unknown differences in the conditions affect the proportion of +the sexes. Thus with mankind, the male births in England are as 104.5, in +Russia as 108.9, and with the Jews of Livonia as 120, to 100 female births. +But I shall recur to this curious point of the excess of male births in the +supplement to this chapter. At the Cape of Good Hope, however, male +children of European extraction have been born during several years in the +proportion of between 90 and 99 to 100 female children. + +For our present purpose we are concerned with the proportions of the sexes, +not only at birth, but also at maturity, and this adds another element of +doubt; for it is a well-ascertained fact that with man the number of males +dying before or during birth, and during the first two years of infancy, is +considerably larger than that of females. So it almost certainly is with +male lambs, and probably with some other animals. The males of some +species kill one another by fighting; or they drive one another about until +they become greatly emaciated. They must also be often exposed to various +dangers, whilst wandering about in eager search for the females. In many +kinds of fish the males are much smaller than the females, and they are +believed often to be devoured by the latter, or by other fishes. The +females of some birds appear to die earlier than the males; they are also +liable to be destroyed on their nests, or whilst in charge of their young. +With insects the female larvae are often larger than those of the males, +and would consequently be more likely to be devoured. In some cases the +mature females are less active and less rapid in their movements than the +males, and could not escape so well from danger. Hence, with animals in a +state of nature, we must rely on mere estimation, in order to judge of the +proportions of the sexes at maturity; and this is but little trustworthy, +except when the inequality is strongly marked. Nevertheless, as far as a +judgment can be formed, we may conclude from the facts given in the +supplement, that the males of some few mammals, of many birds, of some fish +and insects, are considerably more numerous than the females. + +The proportion between the sexes fluctuates slightly during successive +years: thus with race-horses, for every 100 mares born the stallions +varied from 107.1 in one year to 92.6 in another year, and with greyhounds +from 116.3 to 95.3. But had larger numbers been tabulated throughout an +area more extensive than England, these fluctuations would probably have +disappeared; and such as they are, would hardly suffice to lead to +effective sexual selection in a state of nature. Nevertheless, in the +cases of some few wild animals, as shewn in the supplement, the proportions +seem to fluctuate either during different seasons or in different +localities in a sufficient degree to lead to such selection. For it should +be observed that any advantage, gained during certain years or in certain +localities by those males which were able to conquer their rivals, or were +the most attractive to the females, would probably be transmitted to the +offspring, and would not subsequently be eliminated. During the succeeding +seasons, when, from the equality of the sexes, every male was able to +procure a female, the stronger or more attractive males previously produced +would still have at least as good a chance of leaving offspring as the +weaker or less attractive. + +POLYGAMY. + +The practice of polygamy leads to the same results as would follow from an +actual inequality in the number of the sexes; for if each male secures two +or more females, many males cannot pair; and the latter assuredly will be +the weaker or less attractive individuals. Many mammals and some few birds +are polygamous, but with animals belonging to the lower classes I have +found no evidence of this habit. The intellectual powers of such animals +are, perhaps, not sufficient to lead them to collect and guard a harem of +females. That some relation exists between polygamy and the development of +secondary sexual characters, appears nearly certain; and this supports the +view that a numerical preponderance of males would be eminently favourable +to the action of sexual selection. Nevertheless many animals, which are +strictly monogamous, especially birds, display strongly-marked secondary +sexual characters; whilst some few animals, which are polygamous, do not +have such characters. + +We will first briefly run through the mammals, and then turn to birds. The +gorilla seems to be polygamous, and the male differs considerably from the +female; so it is with some baboons, which live in herds containing twice as +many adult females as males. In South America the Mycetes caraya presents +well-marked sexual differences, in colour, beard, and vocal organs; and the +male generally lives with two or three wives: the male of the Cebus +capucinus differs somewhat from the female, and appears to be polygamous. +(10. On the Gorilla, Savage and Wyman, 'Boston Journal of Natural +History,' vol. v. 1845-47, p. 423. On Cynocephalus, Brehm, 'Thierleben,' +B. i. 1864, s. 77. On Mycetes, Rengger, 'Naturgeschichte der Säugethiere +von Paraguay,' 1830, ss. 14, 20. On Cebus, Brehm, ibid. s. 108.) Little +is known on this head with respect to most other monkeys, but some species +are strictly monogamous. The ruminants are eminently polygamous, and they +present sexual differences more frequently than almost any other group of +mammals; this holds good, especially in their weapons, but also in other +characters. Most deer, cattle, and sheep are polygamous; as are most +antelopes, though some are monogamous. Sir Andrew Smith, in speaking of +the antelopes of South Africa, says that in herds of about a dozen there +was rarely more than one mature male. The Asiatic Antilope saiga appears +to be the most inordinate polygamist in the world; for Pallas (11. Pallas, +'Spicilegia Zoolog., Fasc.' xii. 1777, p. 29. Sir Andrew Smith, +'Illustrations of the Zoology of S. Africa,' 1849, pl. 29, on the Kobus. +Owen, in his 'Anatomy of Vertebrates' (vol. iii. 1868, p. 633) gives a +table shewing incidentally which species of antelopes are gregarious.) +states that the male drives away all rivals, and collects a herd of about a +hundred females and kids together; the female is hornless and has softer +hair, but does not otherwise differ much from the male. The wild horse of +the Falkland Islands and of the Western States of N. America is polygamous, +but, except in his greater size and in the proportions of his body, differs +but little from the mare. The wild boar presents well-marked sexual +characters, in his great tusks and some other points. In Europe and in +India he leads a solitary life, except during the breeding-season; but as +is believed by Sir W. Elliot, who has had many opportunities in India of +observing this animal, he consorts at this season with several females. +Whether this holds good in Europe is doubtful, but it is supported by some +evidence. The adult male Indian elephant, like the boar, passes much of +his time in solitude; but as Dr. Campbell states, when with others, "It is +rare to find more than one male with a whole herd of females"; the larger +males expelling or killing the smaller and weaker ones. The male differs +from the female in his immense tusks, greater size, strength, and +endurance; so great is the difference in these respects that the males when +caught are valued at one-fifth more than the females. (12. Dr. Campbell, +in 'Proc. Zoolog. Soc.' 1869, p. 138. See also an interesting paper by +Lieut. Johnstone, in 'Proceedings, Asiatic Society of Bengal,' May 1868.) +The sexes of other pachydermatous animals differ very little or not at all, +and, as far as known, they are not polygamists. Nor have I heard of any +species in the Orders of Cheiroptera, Edentata, Insectivora and Rodents +being polygamous, excepting that amongst the Rodents, the common rat, +according to some rat-catchers, lives with several females. Nevertheless +the two sexes of some sloths (Edentata) differ in the character and colour +of certain patches of hair on their shoulders. (13. Dr. Gray, in 'Annals +and Magazine of Natural History,' 1871, p. 302.) And many kinds of bats +(Cheiroptera) present well-marked sexual differences, chiefly in the males +possessing odoriferous glands and pouches, and by their being of a lighter +colour. (14. See Dr. Dobson's excellent paper in 'Proceedings of the +Zoological Society,' 1873, p. 241.) In the great order of Rodents, as far +as I can learn, the sexes rarely differ, and when they do so, it is but +slightly in the tint of the fur. + +As I hear from Sir Andrew Smith, the lion in South Africa sometimes lives +with a single female, but generally with more, and, in one case, was found +with as many as five females; so that he is polygamous. As far as I can +discover, he is the only polygamist amongst all the terrestrial Carnivora, +and he alone presents well-marked sexual characters. If, however, we turn +to the marine Carnivora, as we shall hereafter see, the case is widely +different; for many species of seals offer extraordinary sexual +differences, and they are eminently polygamous. Thus, according to Peron, +the male sea-elephant of the Southern Ocean always possesses several +females, and the sea-lion of Forster is said to be surrounded by from +twenty to thirty females. In the North, the male sea-bear of Steller is +accompanied by even a greater number of females. It is an interesting +fact, as Dr. Gill remarks (15. 'The Eared Seals,' American Naturalist, +vol. iv. Jan. 1871.), that in the monogamous species, "or those living in +small communities, there is little difference in size between the males and +females; in the social species, or rather those of which the males have +harems, the males are vastly larger than the females." + +Amongst birds, many species, the sexes of which differ greatly from each +other, are certainly monogamous. In Great Britain we see well-marked +sexual differences, for instance, in the wild-duck which pairs with a +single female, the common blackbird, and the bullfinch which is said to +pair for life. I am informed by Mr. Wallace that the like is true of the +Chatterers or Cotingidae of South America, and of many other birds. In +several groups I have not been able to discover whether the species are +polygamous or monogamous. Lesson says that birds of paradise, so +remarkable for their sexual differences, are polygamous, but Mr. Wallace +doubts whether he had sufficient evidence. Mr. Salvin tells me he has been +led to believe that humming-birds are polygamous. The male widow-bird, +remarkable for his caudal plumes, certainly seems to be a polygamist. (16. +'The Ibis,' vol. iii. 1861, p. 133, on the Progne Widow-bird. See also on +the Vidua axillaris, ibid. vol. ii. 1860, p. 211. On the polygamy of the +Capercailzie and Great Bustard, see L. Lloyd, 'Game Birds of Sweden,' 1867, +pp. 19, and 182. Montagu and Selby speak of the Black Grouse as polygamous +and of the Red Grouse as monogamous.) I have been assured by Mr. Jenner +Weir and by others, that it is somewhat common for three starlings to +frequent the same nest; but whether this is a case of polygamy or polyandry +has not been ascertained. + +The Gallinaceae exhibit almost as strongly marked sexual differences as +birds of paradise or humming-birds, and many of the species are, as is well +known, polygamous; others being strictly monogamous. What a contrast is +presented between the sexes of the polygamous peacock or pheasant, and the +monogamous guinea-fowl or partridge! Many similar cases could be given, as +in the grouse tribe, in which the males of the polygamous capercailzie and +black-cock differ greatly from the females; whilst the sexes of the +monogamous red grouse and ptarmigan differ very little. In the Cursores, +except amongst the bustards, few species offer strongly-marked sexual +differences, and the great bustard (Otis tarda) is said to be polygamous. +With the Grallatores, extremely few species differ sexually, but the ruff +(Machetes pugnax) affords a marked exception, and this species is believed +by Montagu to be a polygamist. Hence it appears that amongst birds there +often exists a close relation between polygamy and the development of +strongly-marked sexual differences. I asked Mr. Bartlett, of the +Zoological Gardens, who has had very large experience with birds, whether +the male tragopan (one of the Gallinaceae) was polygamous, and I was struck +by his answering, "I do not know, but should think so from his splendid +colours." + +It deserves notice that the instinct of pairing with a single female is +easily lost under domestication. The wild-duck is strictly monogamous, the +domestic-duck highly polygamous. The Rev. W.D. Fox informs me that out of +some half-tamed wild-ducks, on a large pond in his neighbourhood, so many +mallards were shot by the gamekeeper that only one was left for every seven +or eight females; yet unusually large broods were reared. The guinea-fowl +is strictly monogamous; but Mr. Fox finds that his birds succeed best when +he keeps one cock to two or three hens. Canary-birds pair in a state of +nature, but the breeders in England successfully put one male to four or +five females. I have noticed these cases, as rendering it probable that +wild monogamous species might readily become either temporarily or +permanently polygamous. + +Too little is known of the habits of reptiles and fishes to enable us to +speak of their marriage arrangements. The stickle-back (Gasterosteus), +however, is said to be a polygamist (17. Noel Humphreys, 'River Gardens,' +1857.); and the male during the breeding-season differs conspicuously from +the female. + +To sum up on the means through which, as far as we can judge, sexual +selection has led to the development of secondary sexual characters. It +has been shewn that the largest number of vigorous offspring will be reared +from the pairing of the strongest and best-armed males, victorious in +contests over other males, with the most vigorous and best-nourished +females, which are the first to breed in the spring. If such females +select the more attractive, and at the same time vigorous males, they will +rear a larger number of offspring than the retarded females, which must +pair with the less vigorous and less attractive males. So it will be if +the more vigorous males select the more attractive and at the same time +healthy and vigorous females; and this will especially hold good if the +male defends the female, and aids in providing food for the young. The +advantage thus gained by the more vigorous pairs in rearing a larger number +of offspring has apparently sufficed to render sexual selection efficient. +But a large numerical preponderance of males over females will be still +more efficient; whether the preponderance is only occasional and local, or +permanent; whether it occurs at birth, or afterwards from the greater +destruction of the females; or whether it indirectly follows from the +practice of polygamy. + +THE MALE GENERALLY MORE MODIFIED THAN THE FEMALE. + +Throughout the animal kingdom, when the sexes differ in external +appearance, it is, with rare exceptions, the male which has been the more +modified; for, generally, the female retains a closer resemblance to the +young of her own species, and to other adult members of the same group. +The cause of this seems to lie in the males of almost all animals having +stronger passions than the females. Hence it is the males that fight +together and sedulously display their charms before the females; and the +victors transmit their superiority to their male offspring. Why both sexes +do not thus acquire the characters of their fathers, will be considered +hereafter. That the males of all mammals eagerly pursue the females is +notorious to every one. So it is with birds; but many cock birds do not so +much pursue the hen, as display their plumage, perform strange antics, and +pour forth their song in her presence. The male in the few fish observed +seems much more eager than the female; and the same is true of alligators, +and apparently of Batrachians. Throughout the enormous class of insects, +as Kirby remarks, "the law is that the male shall seek the female." (18. +Kirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 342.) +Two good authorities, Mr. Blackwall and Mr. C. Spence Bate, tell me that +the males of spiders and crustaceans are more active and more erratic in +their habits than the females. When the organs of sense or locomotion are +present in the one sex of insects and crustaceans and absent in the other, +or when, as is frequently the case, they are more highly developed in the +one than in the other, it is, as far as I can discover, almost invariably +the male which retains such organs, or has them most developed; and this +shews that the male is the more active member in the courtship of the +sexes. (19. One parasitic Hymenopterous insect (Westwood, 'Modern Class. +of Insects,' vol. ii. p. 160) forms an exception to the rule, as the male +has rudimentary wings, and never quits the cell in which it is born, whilst +the female has well-developed wings. Audouin believes that the females of +this species are impregnated by the males which are born in the same cells +with them; but it is much more probable that the females visit other cells, +so that close inter-breeding is thus avoided. We shall hereafter meet in +various classes, with a few exceptional cases, in which the female, instead +of the male, is the seeker and wooer.) + +The female, on the other hand, with the rarest exceptions, is less eager +than the male. As the illustrious Hunter (20. 'Essays and Observations,' +edited by Owen, vol. i. 1861, p. 194.) long ago observed, she generally +"requires to be courted;" she is coy, and may often be seen endeavouring +for a long time to escape from the male. Every observer of the habits of +animals will be able to call to mind instances of this kind. It is shewn +by various facts, given hereafter, and by the results fairly attributable +to sexual selection, that the female, though comparatively passive, +generally exerts some choice and accepts one male in preference to others. +Or she may accept, as appearances would sometimes lead us to believe, not +the male which is the most attractive to her, but the one which is the +least distasteful. The exertion of some choice on the part of the female +seems a law almost as general as the eagerness of the male. + +We are naturally led to enquire why the male, in so many and such distinct +classes, has become more eager than the female, so that he searches for +her, and plays the more active part in courtship. It would be no advantage +and some loss of power if each sex searched for the other; but why should +the male almost always be the seeker? The ovules of plants after +fertilisation have to be nourished for a time; hence the pollen is +necessarily brought to the female organs--being placed on the stigma, by +means of insects or the wind, or by the spontaneous movements of the +stamens; and in the Algae, etc., by the locomotive power of the +antherozooids. With lowly-organised aquatic animals, permanently affixed +to the same spot and having their sexes separate, the male element is +invariably brought to the female; and of this we can see the reason, for +even if the ova were detached before fertilisation, and did not require +subsequent nourishment or protection, there would yet be greater difficulty +in transporting them than the male element, because, being larger than the +latter, they are produced in far smaller numbers. So that many of the +lower animals are, in this respect, analogous with plants. (21. Prof. +Sachs ('Lehrbuch der Botanik,' 1870, S. 633) in speaking of the male and +female reproductive cells, remarks, "verhält sich die eine bei der +Vereinigung activ,...die andere erscheint bei der Vereinigung passiv.") +The males of affixed and aquatic animals having been led to emit their +fertilising element in this way, it is natural that any of their +descendants, which rose in the scale and became locomotive, should retain +the same habit; and they would approach the female as closely as possible, +in order not to risk the loss of the fertilising element in a long passage +of it through the water. With some few of the lower animals, the females +alone are fixed, and the males of these must be the seekers. But it is +difficult to understand why the males of species, of which the progenitors +were primordially free, should invariably have acquired the habit of +approaching the females, instead of being approached by them. But in all +cases, in order that the males should seek efficiently, it would be +necessary that they should be endowed with strong passions; and the +acquirement of such passions would naturally follow from the more eager +leaving a larger number of offspring than the less eager. + +The great eagerness of the males has thus indirectly led to their much more +frequently developing secondary sexual characters than the females. But +the development of such characters would be much aided, if the males were +more liable to vary than the females--as I concluded they were--after a +long study of domesticated animals. Von Nathusius, who has had very wide +experience, is strongly of the same opinion. (22. 'Vorträge uber +Viehzucht,' 1872, p. 63.) Good evidence also in favour of this conclusion +can be produced by a comparison of the two sexes in mankind. During the +Novara Expedition (23. 'Reise der Novara: Anthropolog. Theil,' 1867, ss. +216-269. The results were calculated by Dr. Weisbach from measurements +made by Drs. K. Scherzer and Schwarz. On the greater variability of the +males of domesticated animals, see my 'Variation of Animals and Plants +under Domestication,' vol. ii. 1868, p. 75.) a vast number of measurements +was made of various parts of the body in different races, and the men were +found in almost every case to present a greater range of variation than the +women; but I shall have to recur to this subject in a future chapter. Mr. +J. Wood (24. 'Proceedings of the Royal Society,' vol. xvi. July 1868, pp. +519 and 524.), who has carefully attended to the variation of the muscles +in man, puts in italics the conclusion that "the greatest number of +abnormalities in each subject is found in the males." He had previously +remarked that "altogether in 102 subjects, the varieties of redundancy were +found to be half as many again as in females, contrasting widely with the +greater frequency of deficiency in females before described." Professor +Macalister likewise remarks (25. 'Proc. Royal Irish Academy,' vol. x. +1868, p. 123.) that variations in the muscles "are probably more common in +males than females." Certain muscles which are not normally present in +mankind are also more frequently developed in the male than in the female +sex, although exceptions to this rule are said to occur. Dr. Burt Wilder +(26. 'Massachusetts Medical Society,' vol. ii. No. 3, 1868, p. 9.) has +tabulated the cases of 152 individuals with supernumerary digits, of which +86 were males, and 39, or less than half, females, the remaining 27 being +of unknown sex. It should not, however, be overlooked that women would +more frequently endeavour to conceal a deformity of this kind than men. +Again, Dr. L. Meyer asserts that the ears of man are more variable in form +than those of a woman. (27. 'Archiv fur Path. Anat. und Phys.' 1871, p. +488.) Lastly the temperature is more variable in man than in woman. (28. +The conclusions recently arrived at by Dr. J. Stockton Hough, on the +temperature of man, are given in the 'Pop. Sci. Review,' Jan. 1st, 1874, p. +97.) + +The cause of the greater general variability in the male sex, than in the +female is unknown, except in so far as secondary sexual characters are +extraordinarily variable, and are usually confined to the males; and, as we +shall presently see, this fact is, to a certain extent, intelligible. +Through the action of sexual and natural selection male animals have been +rendered in very many instances widely different from their females; but +independently of selection the two sexes, from differing constitutionally, +tend to vary in a somewhat different manner. The female has to expend much +organic matter in the formation of her ova, whereas the male expends much +force in fierce contests with his rivals, in wandering about in search of +the female, in exerting his voice, pouring out odoriferous secretions, +etc.: and this expenditure is generally concentrated within a short +period. The great vigour of the male during the season of love seems often +to intensify his colours, independently of any marked difference from the +female. (29. Prof. Mantegazza is inclined to believe ('Lettera a Carlo +Darwin,' 'Archivio per l'Anthropologia,' 1871, p. 306) that the bright +colours, common in so many male animals, are due to the presence and +retention by them of the spermatic fluid; but this can hardly be the case; +for many male birds, for instance young pheasants, become brightly coloured +in the autumn of their first year.) In mankind, and even as low down in +the organic scale as in the Lepidoptera, the temperature of the body is +higher in the male than in the female, accompanied in the case of man by a +slower pulse. (30. For mankind, see Dr. J. Stockton Hough, whose +conclusions are given in the 'Popular Science Review,' 1874, p. 97. See +Girard's observations on the Lepidoptera, as given in the 'Zoological +Record,' 1869, p. 347.) On the whole the expenditure of matter and force +by the two sexes is probably nearly equal, though effected in very +different ways and at different rates. + +From the causes just specified the two sexes can hardly fail to differ +somewhat in constitution, at least during the breeding-season; and, +although they may be subjected to exactly the same conditions, they will +tend to vary in a different manner. If such variations are of no service +to either sex, they will not be accumulated and increased by sexual or +natural selection. Nevertheless, they may become permanent if the exciting +cause acts permanently; and in accordance with a frequent form of +inheritance they may be transmitted to that sex alone in which they first +appeared. In this case the two sexes will come to present permanent, yet +unimportant, differences of character. For instance, Mr. Allen shews that +with a large number of birds inhabiting the northern and southern United +States, the specimens from the south are darker-coloured than those from +the north; and this seems to be the direct result of the difference in +temperature, light, etc., between the two regions. Now, in some few cases, +the two sexes of the same species appear to have been differently affected; +in the Agelaeus phoeniceus the males have had their colours greatly +intensified in the south; whereas with Cardinalis virginianus it is the +females which have been thus affected; with Quiscalus major the females +have been rendered extremely variable in tint, whilst the males remain +nearly uniform. (31. 'Mammals and Birds of E. Florida,' pp. 234, 280, +295.) + +A few exceptional cases occur in various classes of animals, in which the +females instead of the males have acquired well pronounced secondary sexual +characters, such as brighter colours, greater size, strength, or pugnacity. +With birds there has sometimes been a complete transposition of the +ordinary characters proper to each sex; the females having become the more +eager in courtship, the males remaining comparatively passive, but +apparently selecting the more attractive females, as we may infer from the +results. Certain hen birds have thus been rendered more highly coloured or +otherwise ornamented, as well as more powerful and pugnacious than the +cocks; these characters being transmitted to the female offspring alone. + +It may be suggested that in some cases a double process of selection has +been carried on; that the males have selected the more attractive females, +and the latter the more attractive males. This process, however, though it +might lead to the modification of both sexes, would not make the one sex +different from the other, unless indeed their tastes for the beautiful +differed; but this is a supposition too improbable to be worth considering +in the case of any animal, excepting man. There are, however, many animals +in which the sexes resemble each other, both being furnished with the same +ornaments, which analogy would lead us to attribute to the agency of sexual +selection. In such cases it may be suggested with more plausibility, that +there has been a double or mutual process of sexual selection; the more +vigorous and precocious females selecting the more attractive and vigorous +males, the latter rejecting all except the more attractive females. But +from what we know of the habits of animals, this view is hardly probable, +for the male is generally eager to pair with any female. It is more +probable that the ornaments common to both sexes were acquired by one sex, +generally the male, and then transmitted to the offspring of both sexes. +If, indeed, during a lengthened period the males of any species were +greatly to exceed the females in number, and then during another lengthened +period, but under different conditions, the reverse were to occur, a +double, but not simultaneous, process of sexual selection might easily be +carried on, by which the two sexes might be rendered widely different. + +We shall hereafter see that many animals exist, of which neither sex is +brilliantly coloured or provided with special ornaments, and yet the +members of both sexes or of one alone have probably acquired simple +colours, such as white or black, through sexual selection. The absence of +bright tints or other ornaments may be the result of variations of the +right kind never having occurred, or of the animals themselves having +preferred plain black or white. Obscure tints have often been developed +through natural selection for the sake of protection, and the acquirement +through sexual selection of conspicuous colours, appears to have been +sometimes checked from the danger thus incurred. But in other cases the +males during long ages may have struggled together for the possession of +the females, and yet no effect will have been produced, unless a larger +number of offspring were left by the more successful males to inherit their +superiority, than by the less successful: and this, as previously shewn, +depends on many complex contingencies. + +Sexual selection acts in a less rigorous manner than natural selection. +The latter produces its effects by the life or death at all ages of the +more or less successful individuals. Death, indeed, not rarely ensues from +the conflicts of rival males. But generally the less successful male +merely fails to obtain a female, or obtains a retarded and less vigorous +female later in the season, or, if polygamous, obtains fewer females; so +that they leave fewer, less vigorous, or no offspring. In regard to +structures acquired through ordinary or natural selection, there is in most +cases, as long as the conditions of life remain the same, a limit to the +amount of advantageous modification in relation to certain special +purposes; but in regard to structures adapted to make one male victorious +over another, either in fighting or in charming the female, there is no +definite limit to the amount of advantageous modification; so that as long +as the proper variations arise the work of sexual selection will go on. +This circumstance may partly account for the frequent and extraordinary +amount of variability presented by secondary sexual characters. +Nevertheless, natural selection will determine that such characters shall +not be acquired by the victorious males, if they would be highly injurious, +either by expending too much of their vital powers, or by exposing them to +any great danger. The development, however, of certain structures--of the +horns, for instance, in certain stags--has been carried to a wonderful +extreme; and in some cases to an extreme which, as far as the general +conditions of life are concerned, must be slightly injurious to the male. +From this fact we learn that the advantages which favoured males derive +from conquering other males in battle or courtship, and thus leaving a +numerous progeny, are in the long run greater than those derived from +rather more perfect adaptation to their conditions of life. We shall +further see, and it could never have been anticipated, that the power to +charm the female has sometimes been more important than the power to +conquer other males in battle. + +LAWS OF INHERITANCE. + +In order to understand how sexual selection has acted on many animals of +many classes, and in the course of ages has produced a conspicuous result, +it is necessary to bear in mind the laws of inheritance, as far as they are +known. Two distinct elements are included under the term "inheritance"-- +the transmission, and the development of characters; but as these generally +go together, the distinction is often overlooked. We see this distinction +in those characters which are transmitted through the early years of life, +but are developed only at maturity or during old age. We see the same +distinction more clearly with secondary sexual characters, for these are +transmitted through both sexes, though developed in one alone. That they +are present in both sexes, is manifest when two species, having strongly- +marked sexual characters, are crossed, for each transmits the characters +proper to its own male and female sex to the hybrid offspring of either +sex. The same fact is likewise manifest, when characters proper to the +male are occasionally developed in the female when she grows old or becomes +diseased, as, for instance, when the common hen assumes the flowing tail- +feathers, hackles, comb, spurs, voice, and even pugnacity of the cock. +Conversely, the same thing is evident, more or less plainly, with castrated +males. Again, independently of old age or disease, characters are +occasionally transferred from the male to the female, as when, in certain +breeds of the fowl, spurs regularly appear in the young and healthy +females. But in truth they are simply developed in the female; for in +every breed each detail in the structure of the spur is transmitted through +the female to her male offspring. Many cases will hereafter be given, +where the female exhibits, more or less perfectly, characters proper to the +male, in whom they must have been first developed, and then transferred to +the female. The converse case of the first development of characters in +the female and of transference to the male, is less frequent; it will +therefore be well to give one striking instance. With bees the pollen- +collecting apparatus is used by the female alone for gathering pollen for +the larvae, yet in most of the species it is partially developed in the +males to whom it is quite useless, and it is perfectly developed in the +males of Bombus or the humble-bee. (32. H. Muller, 'Anwendung der +Darwin'schen Lehre,' etc., Verh. d. n. V. Jahrg., xxix. p. 42.) As not a +single other Hymenopterous insect, not even the wasp, which is closely +allied to the bee, is provided with a pollen-collecting apparatus, we have +no grounds for supposing that male bees primordially collected pollen as +well as the females; although we have some reason to suspect that male +mammals primordially suckled their young as well as the females. Lastly, +in all cases of reversion, characters are transmitted through two, three, +or many more generations, and are then developed under certain unknown +favourable conditions. This important distinction between transmission and +development will be best kept in mind by the aid of the hypothesis of +pangenesis. According to this hypothesis, every unit or cell of the body +throws off gemmules or undeveloped atoms, which are transmitted to the +offspring of both sexes, and are multiplied by self-division. They may +remain undeveloped during the early years of life or during successive +generations; and their development into units or cells, like those from +which they were derived, depends on their affinity for, and union with +other units or cells previously developed in the due order of growth. + +INHERITANCE AT CORRESPONDING PERIODS OF LIFE. + +This tendency is well established. A new character, appearing in a young +animal, whether it lasts throughout life or is only transient, will, in +general, reappear in the offspring at the same age and last for the same +time. If, on the other hand, a new character appears at maturity, or even +during old age, it tends to reappear in the offspring at the same advanced +age. When deviations from this rule occur, the transmitted characters much +oftener appear before, than after the corresponding age. As I have dwelt +on this subject sufficiently in another work (33. The 'Variation of +Animals and Plants under Domestication,' vol. ii. 1868, p. 75. In the last +chapter but one, the provisional hypothesis of pangenesis, above alluded +to, is fully explained.), I will here merely give two or three instances, +for the sake of recalling the subject to the reader's mind. In several +breeds of the Fowl, the down-covered chickens, the young birds in their +first true plumage, and the adults differ greatly from one another, as well +as from their common parent-form, the Gallus bankiva; and these characters +are faithfully transmitted by each breed to their offspring at the +corresponding periods of life. For instance, the chickens of spangled +Hamburgs, whilst covered with down, have a few dark spots on the head and +rump, but are not striped longitudinally, as in many other breeds; in their +first true plumage, "they are beautifully pencilled," that is each feather +is transversely marked by numerous dark bars; but in their second plumage +the feathers all become spangled or tipped with a dark round spot. (34. +These facts are given on the high authority of a great breeder, Mr. Teebay; +see Tegetmeier's 'Poultry Book,' 1868, p. 158. On the characters of +chickens of different breeds, and on the breeds of the pigeon, alluded to +in the following paragraph, see 'Variation of Animals,' etc., vol. i. pp. +160, 249; vol. ii. p. 77.) Hence in this breed variations have occurred +at, and been transmitted to, three distinct periods of life. The Pigeon +offers a more remarkable case, because the aboriginal parent species does +not undergo any change of plumage with advancing age, excepting that at +maturity the breast becomes more iridescent; yet there are breeds which do +not acquire their characteristic colours until they have moulted two, +three, or four times; and these modifications of plumage are regularly +transmitted. + +INHERITANCE AT CORRESPONDING SEASONS OF THE YEAR. + +With animals in a state of nature, innumerable instances occur of +characters appearing periodically at different seasons. We see this in the +horns of the stag, and in the fur of Artic animals which becomes thick and +white during the winter. Many birds acquire bright colours and other +decorations during the breeding-season alone. Pallas states (35. 'Novae +species Quadrupedum e Glirium ordine,' 1778, p. 7. On the transmission of +colour by the horse, see 'Variation of Animals and Plants under +Domestication,' vol. i. p. 51. Also vol. ii. p. 71, for a general +discussion on 'Inheritance as limited by Sex.'), that in Siberia domestic +cattle and horses become lighter-coloured during the winter; and I have +myself observed, and heard of similar strongly marked changes of colour, +that is, from brownish cream-colour or reddish-brown to a perfect white, in +several ponies in England. Although I do not know that this tendency to +change the colour of the coat during different seasons is transmitted, yet +it probably is so, as all shades of colour are strongly inherited by the +horse. Nor is this form of inheritance, as limited by the seasons, more +remarkable than its limitation by age or sex. + +INHERITANCE AS LIMITED BY SEX. + +The equal transmission of characters to both sexes is the commonest form of +inheritance, at least with those animals which do not present strongly- +marked sexual differences, and indeed with many of these. But characters +are somewhat commonly transferred exclusively to that sex, in which they +first appear. Ample evidence on this head has been advanced in my work on +'Variation under Domestication,' but a few instances may here be given. +There are breeds of the sheep and goat, in which the horns of the male +differ greatly in shape from those of the female; and these differences, +acquired under domestication, are regularly transmitted to the same sex. +As a rule, it is the females alone in cats which are tortoise-shell, the +corresponding colour in the males being rusty-red. With most breeds of the +fowl, the characters proper to each sex are transmitted to the same sex +alone. So general is this form of transmission that it is an anomaly when +variations in certain breeds are transmitted equally to both sexes. There +are also certain sub-breeds of the fowl in which the males can hardly be +distinguished from one another, whilst the females differ considerably in +colour. The sexes of the pigeon in the parent-species do not differ in any +external character; nevertheless, in certain domesticated breeds the male +is coloured differently from the female. (36. Dr. Chapuis, 'Le Pigeon +Voyageur Belge,' 1865, p. 87. Boitard et Corbie, 'Les Pigeons de Volière,' +etc., 1824, p. 173. See, also, on similar differences in certain breeds at +Modena, 'Le variazioni dei Colombi domestici,' del Paolo Bonizzi, 1873.) +The wattle in the English Carrier pigeon, and the crop in the Pouter, are +more highly developed in the male than in the female; and although these +characters have been gained through long-continued selection by man, the +slight differences between the sexes are wholly due to the form of +inheritance which has prevailed; for they have arisen, not from, but rather +in opposition to, the wish of the breeder. + + +Most of our domestic races have been formed by the accumulation of many +slight variations; and as some of the successive steps have been +transmitted to one sex alone, and some to both sexes, we find in the +different breeds of the same species all gradations between great sexual +dissimilarity and complete similarity. Instances have already been given +with the breeds of the fowl and pigeon, and under nature analogous cases +are common. With animals under domestication, but whether in nature I will +not venture to say, one sex may lose characters proper to it, and may thus +come somewhat to resemble the opposite sex; for instance, the males of some +breeds of the fowl have lost their masculine tail-plumes and hackles. On +the other hand, the differences between the sexes may be increased under +domestication, as with merino sheep, in which the ewes have lost their +horns. Again, characters proper to one sex may suddenly appear in the +other sex; as in those sub-breeds of the fowl in which the hens acquire +spurs whilst young; or, as in certain Polish sub-breeds, in which the +females, as there is reason to believe, originally acquired a crest, and +subsequently transferred it to the males. All these cases are intelligible +on the hypothesis of pangenesis; for they depend on the gemmules of certain +parts, although present in both sexes, becoming, through the influence of +domestication, either dormant or developed in either sex. + +There is one difficult question which it will be convenient to defer to a +future chapter; namely, whether a character at first developed in both +sexes, could through selection be limited in its development to one sex +alone. If, for instance, a breeder observed that some of his pigeons (of +which the characters are usually transferred in an equal degree to both +sexes) varied into pale blue, could he by long-continued selection make a +breed, in which the males alone should be of this tint, whilst the females +remained unchanged? I will here only say, that this, though perhaps not +impossible, would be extremely difficult; for the natural result of +breeding from the pale-blue males would be to change the whole stock of +both sexes to this tint. If, however, variations of the desired tint +appeared, which were from the first limited in their development to the +male sex, there would not be the least difficulty in making a breed with +the two sexes of a different colour, as indeed has been effected with a +Belgian breed, in which the males alone are streaked with black. In a +similar manner, if any variation appeared in a female pigeon, which was +from the first sexually limited in its development to the females, it would +be easy to make a breed with the females alone thus characterised; but if +the variation was not thus originally limited, the process would be +extremely difficult, perhaps impossible. (37. Since the publication of +the first edition of this work, it has been highly satisfactory to me to +find the following remarks (the 'Field,' Sept. 1872) from so experienced a +breeder as Mr. Tegetmeier. After describing some curious cases in pigeons, +of the transmission of colour by one sex alone, and the formation of a sub- +breed with this character, he says: "It is a singular circumstance that +Mr. Darwin should have suggested the possibility of modifying the sexual +colours of birds by a course of artificial selection. When he did so, he +was in ignorance of these facts that I have related; but it is remarkable +how very closely he suggested the right method of procedure.") + +ON THE RELATION BETWEEN THE PERIOD OF DEVELOPMENT OF A CHARACTER AND ITS +TRANSMISSION TO ONE SEX OR TO BOTH SEXES. + +Why certain characters should be inherited by both sexes, and other +characters by one sex alone, namely by that sex in which the character +first appeared, is in most cases quite unknown. We cannot even conjecture +why with certain sub-breeds of the pigeon, black striae, though transmitted +through the female, should be developed in the male alone, whilst every +other character is equally transferred to both sexes. Why, again, with +cats, the tortoise-shell colour should, with rare exceptions, be developed +in the female alone. The very same character, such as deficient or +supernumerary digits, colour-blindness, etc., may with mankind be inherited +by the males alone of one family, and in another family by the females +alone, though in both cases transmitted through the opposite as well as +through the same sex. (38. References are given in my 'Variation of +Animals and Plants under Domestication,' vol. ii. p. 72.) Although we are +thus ignorant, the two following rules seem often to hold good--that +variations which first appear in either sex at a late period of life, tend +to be developed in the same sex alone; whilst variations which first appear +early in life in either sex tend to be developed in both sexes. I am, +however, far from supposing that this is the sole determining cause. As I +have not elsewhere discussed this subject, and it has an important bearing +on sexual selection, I must here enter into lengthy and somewhat intricate +details. + +It is in itself probable that any character appearing at an early age would +tend to be inherited equally by both sexes, for the sexes do not differ +much in constitution before the power of reproduction is gained. On the +other hand, after this power has been gained and the sexes have come to +differ in constitution, the gemmules (if I may again use the language of +pangenesis) which are cast off from each varying part in the one sex would +be much more likely to possess the proper affinities for uniting with the +tissues of the same sex, and thus becoming developed, than with those of +the opposite sex. + +I was first led to infer that a relation of this kind exists, from the fact +that whenever and in whatever manner the adult male differs from the adult +female, he differs in the same manner from the young of both sexes. The +generality of this fact is quite remarkable: it holds good with almost all +mammals, birds, amphibians, and fishes; also with many crustaceans, +spiders, and some few insects, such as certain orthoptera and libellulae. +In all these cases the variations, through the accumulation of which the +male acquired his proper masculine characters, must have occurred at a +somewhat late period of life; otherwise the young males would have been +similarly characterised; and conformably with our rule, the variations are +transmitted to and developed in the adult males alone. When, on the other +hand, the adult male closely resembles the young of both sexes (these, with +rare exceptions, being alike), he generally resembles the adult female; and +in most of these cases the variations through which the young and old +acquired their present characters, probably occurred, according to our +rule, during youth. But there is here room for doubt, for characters are +sometimes transferred to the offspring at an earlier age than that at which +they first appeared in the parents, so that the parents may have varied +when adult, and have transferred their characters to their offspring whilst +young. There are, moreover, many animals, in which the two sexes closely +resemble each other, and yet both differ from their young: and here the +characters of the adults must have been acquired late in life; +nevertheless, these characters, in apparent contradiction to our rule, are +transferred to both sexes. We must not however, overlook the possibility +or even probability of successive variations of the same nature occurring, +under exposure to similar conditions, simultaneously in both sexes at a +rather late period of life; and in this case the variations would be +transferred to the offspring of both sexes at a corresponding late age; and +there would then be no real contradiction to the rule that variations +occurring late in life are transferred exclusively to the sex in which they +first appeared. This latter rule seems to hold true more generally than +the second one, namely, that variations which occur in either sex early in +life tend to be transferred to both sexes. As it was obviously impossible +even to estimate in how large a number of cases throughout the animal +kingdom these two propositions held good, it occurred to me to investigate +some striking or crucial instances, and to rely on the result. + +An excellent case for investigation is afforded by the Deer family. In all +the species, but one, the horns are developed only in the males, though +certainly transmitted through the females, and capable of abnormal +development in them. In the reindeer, on the other hand, the female is +provided with horns; so that in this species, the horns ought, according to +our rule, to appear early in life, long before the two sexes are mature and +have come to differ much in constitution. In all the other species the +horns ought to appear later in life, which would lead to their development +in that sex alone, in which they first appeared in the progenitor of the +whole Family. Now in seven species, belonging to distinct sections of the +family and inhabiting different regions, in which the stags alone bear +horns, I find that the horns first appear at periods, varying from nine +months after birth in the roebuck, to ten, twelve or even more months in +the stags of the six other and larger species. (39. I am much obliged to +Mr. Cupples for having made enquiries for me in regard to the Roebuck and +Red Deer of Scotland from Mr. Robertson, the experienced head-forester to +the Marquis of Breadalbane. In regard to Fallow-deer, I have to thank Mr. +Eyton and others for information. For the Cervus alces of N. America, see +'Land and Water,' 1868, pp. 221 and 254; and for the C. Virginianus and +strongyloceros of the same continent, see J.D. Caton, in 'Ottawa Acad. of +Nat. Sc.' 1868, p. 13. For Cervus Eldi of Pegu, see Lieut. Beaven, +'Proccedings of the Zoological Society,' 1867, p. 762.) But with the +reindeer the case is widely different; for, as I hear from Prof. Nilsson, +who kindly made special enquiries for me in Lapland, the horns appear in +the young animals within four or five weeks after birth, and at the same +time in both sexes. So that here we have a structure, developed at a most +unusually early age in one species of the family, and likewise common to +both sexes in this one species alone. + +In several kinds of antelopes, only the males are provided with horns, +whilst in the greater number both sexes bear horns. With respect to the +period of development, Mr. Blyth informs me that there was at one time in +the Zoological Gardens a young koodoo (Ant. strepsiceros), of which the +males alone are horned, and also the young of a closely-allied species, the +eland (Ant. oreas), in which both sexes are horned. Now it is in strict +conformity with our rule, that in the young male koodoo, although ten +months old, the horns were remarkably small, considering the size +ultimately attained by them; whilst in the young male eland, although only +three months old, the horns were already very much larger than in the +koodoo. It is also a noticeable fact that in the prong-horned antelope +(40. Antilocapra Americana. I have to thank Dr. Canfield for information +with respect to the horns of the female: see also his paper in +'Proceedings of the Zoological Society,' 1866, p. 109. Also Owen, 'Anatomy +of Vertebrates,' vol. iii. p. 627), only a few of the females, about one in +five, have horns, and these are in a rudimentary state, though sometimes +above four inches long: so that as far as concerns the possession of horns +by the males alone, this species is in an intermediate condition, and the +horns do not appear until about five or six months after birth. Therefore +in comparison with what little we know of the development of the horns in +other antelopes, and from what we do know with respect to the horns of +deer, cattle, etc., those of the prong-horned antelope appear at an +intermediate period of life,--that is, not very early, as in cattle and +sheep, nor very late, as in the larger deer and antelopes. The horns of +sheep, goats, and cattle, which are well developed in both sexes, though +not quite equal in size, can be felt, or even seen, at birth or soon +afterwards. (41. I have been assured that the horns of the sheep in North +Wales can always be felt, and are sometimes even an inch in length, at +birth. Youatt says ('Cattle,' 1834, p. 277), that the prominence of the +frontal bone in cattle penetrates the cutis at birth, and that the horny +matter is soon formed over it.) Our rule, however, seems to fail in some +breeds of sheep, for instance merinos, in which the rams alone are horned; +for I cannot find on enquiry (42. I am greatly indebted to Prof. Victor +Carus for having made enquiries for me, from the highest authorities, with +respect to the merino sheep of Saxony. On the Guinea coast of Africa there +is, however, a breed of sheep in which, as with merinos, the rams alone +bear horns; and Mr. Winwood Reade informs me that in one case observed by +him, a young ram, born on Feb. 10th, first shewed horns on March 6th, so +that in this instance, in conformity with rule, the development of the +horns occurred at a later period of life than in Welsh sheep, in which both +sexes are horned.), that the horns are developed later in life in this +breed than in ordinary sheep in which both sexes are horned. But with +domesticated sheep the presence or absence of horns is not a firmly fixed +character; for a certain proportion of the merino ewes bear small horns, +and some of the rams are hornless; and in most breeds hornless ewes are +occasionally produced. + +Dr. W. Marshall has lately made a special study of the protuberances so +common on the heads of birds (43. 'Über die knochernen Schädelhöcker der +Vögel,' in the 'Niederland. Archiv fur Zoologie,' B.i. Heft 2, 1872.), and +he comes to the following conclusion:--that with those species in which +they are confined to the males, they are developed late in life; whereas +with those species in which they are common to the two sexes, they are +developed at a very early period. This is certainly a striking +confirmation of my two laws of inheritance. + +In most of the species of the splendid family of the Pheasants, the males +differ conspicuously from the females, and they acquire their ornaments at +a rather late period of life. The eared pheasant (Crossoptilon auritum), +however, offers a remarkable exception, for both sexes possess the fine +caudal plumes, the large ear-tufts and the crimson velvet about the head; I +find that all these characters appear very early in life in accordance with +rule. The adult male can, however, be distinguished from the adult female +by the presence of spurs; and conformably with our rule, these do not begin +to be developed before the age of six months, as I am assured by Mr. +Bartlett, and even at this age, the two sexes can hardly be distinguished. +(44. In the common peacock (Pavo cristatus) the male alone possesses +spurs, whilst both sexes of the Java Peacock (P. muticus) offer the unusual +case of being furnished with spurs. Hence I fully expected that in the +latter species they would have been developed earlier in life than in the +common peacock; but M. Hegt of Amsterdam informs me, that with young birds +of the previous year, of both species, compared on April 23rd, 1869, there +was no difference in the development of the spurs. The spurs, however, +were as yet represented merely by slight knobs or elevations. I presume +that I should have been informed if any difference in the rate of +development had been observed subsequently.) The male and female Peacock +differ conspicuously from each other in almost every part of their plumage, +except in the elegant head-crest, which is common to both sexes; and this +is developed very early in life, long before the other ornaments, which are +confined to the male. The wild-duck offers an analogous case, for the +beautiful green speculum on the wings is common to both sexes, though +duller and somewhat smaller in the female, and it is developed early in +life, whilst the curled tail-feathers and other ornaments of the male are +developed later. (45. In some other species of the Duck family the +speculum differs in a greater degree in the two sexes; but I have not been +able to discover whether its full development occurs later in life in the +males of such species, than in the male of the common duck, as ought to be +the case according to our rule. With the allied Mergus cucullatus we have, +however, a case of this kind: the two sexes differ conspicuously in +general plumage, and to a considerable degree in the speculum, which is +pure white in the male and greyish-white in the female. Now the young +males at first entirely resemble the females, and have a greyish-white +speculum, which becomes pure white at an earlier age than that at which the +adult male acquires his other and more strongly-marked sexual differences: +see Audubon, 'Ornithological Biography,' vol. iii. 1835, pp. 249-250.) +Between such extreme cases of close sexual resemblance and wide +dissimilarity, as those of the Crossoptilon and peacock, many intermediate +ones could be given, in which the characters follow our two rules in their +order of development. + +As most insects emerge from the pupal state in a mature condition, it is +doubtful whether the period of development can determine the transference +of their characters to one or to both sexes. But we do not know that the +coloured scales, for instance, in two species of butterflies, in one of +which the sexes differ in colour, whilst in the other they are alike, are +developed at the same relative age in the cocoon. Nor do we know whether +all the scales are simultaneously developed on the wings of the same +species of butterfly, in which certain coloured marks are confined to one +sex, whilst others are common to both sexes. A difference of this kind in +the period of development is not so improbable as it may at first appear; +for with the Orthoptera, which assume their adult state, not by a single +metamorphosis, but by a succession of moults, the young males of some +species at first resemble the females, and acquire their distinctive +masculine characters only at a later moult. Strictly analogous cases occur +at the successive moults of certain male crustaceans. + +We have as yet considered the transference of characters, relatively to +their period of development, only in species in a natural state; we will +now turn to domesticated animals, and first touch on monstrosities and +diseases. The presence of supernumerary digits, and the absence of certain +phalanges, must be determined at an early embryonic period--the tendency to +profuse bleeding is at least congenital, as is probably colour-blindness-- +yet these peculiarities, and other similar ones, are often limited in their +transmission to one sex; so that the rule that characters, developed at an +early period, tend to be transmitted to both sexes, here wholly fails. But +this rule, as before remarked, does not appear to be nearly so general as +the converse one, namely, that characters which appear late in life in one +sex are transmitted exclusively to the same sex. From the fact of the +above abnormal peculiarities becoming attached to one sex, long before the +sexual functions are active, we may infer that there must be some +difference between the sexes at an extremely early age. With respect to +sexually-limited diseases, we know too little of the period at which they +originate, to draw any safe conclusion. Gout, however, seems to fall under +our rule, for it is generally caused by intemperance during manhood, and is +transmitted from the father to his sons in a much more marked manner than +to his daughters. + +In the various domestic breeds of sheep, goats, and cattle, the males +differ from their respective females in the shape or development of their +horns, forehead, mane, dewlap, tail, and hump on the shoulders; and these +peculiarities, in accordance with our rule, are not fully developed until a +rather late period of life. The sexes of dogs do not differ, except that +in certain breeds, especially in the Scotch deer-hound, the male is much +larger and heavier than the female; and, as we shall see in a future +chapter, the male goes on increasing in size to an unusually late period of +life, which, according to rule, will account for his increased size being +transmitted to his male offspring alone. On the other hand, the tortoise- +shell colour, which is confined to female cats, is quite distinct at birth, +and this case violates the rule. There is a breed of pigeons in which the +males alone are streaked with black, and the streaks can be detected even +in the nestlings; but they become more conspicuous at each successive +moult, so that this case partly opposes and partly supports the rule. With +the English Carrier and Pouter pigeons, the full development of the wattle +and the crop occurs rather late in life, and conformably with the rule, +these characters are transmitted in full perfection to the males alone. +The following cases perhaps come within the class previously alluded to, in +which both sexes have varied in the same manner at a rather late period of +life, and have consequently transferred their new characters to both sexes +at a corresponding late period; and if so, these cases are not opposed to +our rule:--there exist sub-breeds of the pigeon, described by Neumeister +(46. 'Das Ganze der Taubenzucht,' 1837, ss. 21, 24. For the case of the +streaked pigeons, see Dr. Chapuis, 'Le pigeon voyageur Belge,' 1865, p. +87.), in which both sexes change their colour during two or three moults +(as is likewise the case with the Almond Tumbler); nevertheless, these +changes, though occurring rather late in life, are common to both sexes. +One variety of the Canary-bird, namely the London Prize, offers a nearly +analogous case. + +With the breeds of the Fowl the inheritance of various characters by one or +both sexes, seems generally determined by the period at which such +characters are developed. Thus in all the many breeds in which the adult +male differs greatly in colour from the female, as well as from the wild +parent-species, he differs also from the young male, so that the newly- +acquired characters must have appeared at a rather late period of life. On +the other hand, in most of the breeds in which the two sexes resemble each +other, the young are coloured in nearly the same manner as their parents, +and this renders it probable that their colours first appeared early in +life. We have instances of this fact in all black and white breeds, in +which the young and old of both sexes are alike; nor can it be maintained +that there is something peculiar in a black or white plumage, which leads +to its transference to both sexes; for the males alone of many natural +species are either black or white, the females being differently coloured. +With the so-called Cuckoo sub-breeds of the fowl, in which the feathers are +transversely pencilled with dark stripes, both sexes and the chickens are +coloured in nearly the same manner. The laced plumage of the Sebright +bantam is the same in both sexes, and in the young chickens the wing- +feathers are distinctly, though imperfectly laced. Spangled Hamburgs, +however, offer a partial exception; for the two sexes, though not quite +alike, resemble each other more closely than do the sexes of the aboriginal +parent-species; yet they acquire their characteristic plumage late in life, +for the chickens are distinctly pencilled. With respect to other +characters besides colour, in the wild-parent species and in most of the +domestic breeds, the males alone possess a well-developed comb; but in the +young of the Spanish fowl it is largely developed at a very early age, and, +in accordance with this early development in the male, it is of unusual +size in the adult female. In the Game breeds pugnacity is developed at a +wonderfully early age, of which curious proofs could be given; and this +character is transmitted to both sexes, so that the hens, from their +extreme pugnacity, are now generally exhibited in separate pens. With the +Polish breeds the bony protuberance of the skull which supports the crest +is partially developed even before the chickens are hatched, and the crest +itself soon begins to grow, though at first feebly (47. For full +particulars and references on all these points respecting the several +breeds of the Fowl, see 'Variation of Animals and Plants under +Domestication,' vol. i. pp. 250, 256. In regard to the higher animals, the +sexual differences which have arisen under domestication are described in +the same work under the head of each species.); and in this breed the +adults of both sexes are characterised by a great bony protuberance and an +immense crest. + +Finally, from what we have now seen of the relation which exists in many +natural species and domesticated races, between the period of the +development of their characters and the manner of their transmission--for +example, the striking fact of the early growth of the horns in the +reindeer, in which both sexes bear horns, in comparison with their much +later growth in the other species in which the male alone bears horns--we +may conclude that one, though not the sole cause of characters being +exclusively inherited by one sex, is their development at a late age. And +secondly, that one, though apparently a less efficient cause of characters +being inherited by both sexes, is their development at an early age, whilst +the sexes differ but little in constitution. It appears, however, that +some difference must exist between the sexes even during a very early +embryonic period, for characters developed at this age not rarely become +attached to one sex. + +SUMMARY AND CONCLUDING REMARKS. + +From the foregoing discussion on the various laws of inheritance, we learn +that the characters of the parents often, or even generally, tend to become +developed in the offspring of the same sex, at the same age, and +periodically at the same season of the year, in which they first appeared +in the parents. But these rules, owing to unknown causes, are far from +being fixed. Hence during the modification of a species, the successive +changes may readily be transmitted in different ways; some to one sex, and +some to both; some to the offspring at one age, and some to the offspring +at all ages. Not only are the laws of inheritance extremely complex, but +so are the causes which induce and govern variability. The variations thus +induced are preserved and accumulated by sexual selection, which is in +itself an extremely complex affair, depending, as it does, on the ardour in +love, the courage, and the rivalry of the males, as well as on the powers +of perception, the taste, and will of the female. Sexual selection will +also be largely dominated by natural selection tending towards the general +welfare of the species. Hence the manner in which the individuals of +either or both sexes have been affected through sexual selection cannot +fail to be complex in the highest degree. + +When variations occur late in life in one sex, and are transmitted to the +same sex at the same age, the other sex and the young are left unmodified. +When they occur late in life, but are transmitted to both sexes at the same +age, the young alone are left unmodified. Variations, however, may occur +at any period of life in one sex or in both, and be transmitted to both +sexes at all ages, and then all the individuals of the species are +similarly modified. In the following chapters it will be seen that all +these cases frequently occur in nature. + +Sexual selection can never act on any animal before the age for +reproduction arrives. From the great eagerness of the male it has +generally acted on this sex and not on the females. The males have thus +become provided with weapons for fighting with their rivals, with organs +for discovering and securely holding the female, and for exciting or +charming her. When the sexes differ in these respects, it is also, as we +have seen, an extremely general law that the adult male differs more or +less from the young male; and we may conclude from this fact that the +successive variations, by which the adult male became modified, did not +generally occur much before the age for reproduction. Whenever some or +many of the variations occurred early in life, the young males would +partake more or less of the characters of the adult males; and differences +of this kind between the old and young males may be observed in many +species of animals. + +It is probable that young male animals have often tended to vary in a +manner which would not only have been of no use to them at an early age, +but would have been actually injurious--as by acquiring bright colours, +which would render them conspicuous to their enemies, or by acquiring +structures, such as great horns, which would expend much vital force in +their development. Variations of this kind occurring in the young males +would almost certainly be eliminated through natural selection. With the +adult and experienced males, on the other hand, the advantages derived from +the acquisition of such characters, would more than counterbalance some +exposure to danger, and some loss of vital force. + +As variations which give to the male a better chance of conquering other +males, or of finding, securing, or charming the opposite sex, would, if +they happened to arise in the female, be of no service to her, they would +not be preserved in her through sexual selection. We have also good +evidence with domesticated animals, that variations of all kinds are, if +not carefully selected, soon lost through intercrossing and accidental +deaths. Consequently in a state of nature, if variations of the above kind +chanced to arise in the female line, and to be transmitted exclusively in +this line, they would be extremely liable to be lost. If, however, the +females varied and transmitted their newly acquired characters to their +offspring of both sexes, the characters which were advantageous to the +males would be preserved by them through sexual selection, and the two +sexes would in consequence be modified in the same manner, although such +characters were of no use to the females: but I shall hereafter have to +recur to these more intricate contingencies. Lastly, the females may +acquire, and apparently have often acquired by transference, characters +from the male sex. + +As variations occurring later in life, and transmitted to one sex alone, +have incessantly been taken advantage of and accumulated through sexual +selection in relation to the reproduction of the species; therefore it +appears, at first sight, an unaccountable fact that similar variations have +not frequently been accumulated through natural selection, in relation to +the ordinary habits of life. If this had occurred, the two sexes would +often have been differently modified, for the sake, for instance, of +capturing prey or of escaping from danger. Differences of this kind +between the two sexes do occasionally occur, especially in the lower +classes. But this implies that the two sexes follow different habits in +their struggles for existence, which is a rare circumstance with the higher +animals. The case, however, is widely different with the reproductive +functions, in which respect the sexes necessarily differ. For variations +in structure which are related to these functions, have often proved of +value to one sex, and from having arisen at a late period of life, have +been transmitted to one sex alone; and such variations, thus preserved and +transmitted, have given rise to secondary sexual characters. + +In the following chapters, I shall treat of the secondary sexual characters +in animals of all classes, and shall endeavour in each case to apply the +principles explained in the present chapter. The lowest classes will +detain us for a very short time, but the higher animals, especially birds, +must be treated at considerable length. It should be borne in mind that +for reasons already assigned, I intend to give only a few illustrative +instances of the innumerable structures by the aid of which the male finds +the female, or, when found, holds her. On the other hand, all structures +and instincts by the aid of which the male conquers other males, and by +which he allures or excites the female, will be fully discussed, as these +are in many ways the most interesting. + +SUPPLEMENT ON THE PROPORTIONAL NUMBERS OF THE TWO SEXES IN ANIMALS +BELONGING TO VARIOUS CLASSES. + +As no one, as far as I can discover, has paid attention to the relative +numbers of the two sexes throughout the animal kingdom, I will here give +such materials as I have been able to collect, although they are extremely +imperfect. They consist in only a few instances of actual enumeration, and +the numbers are not very large. As the proportions are known with +certainty only in mankind, I will first give them as a standard of +comparison. + +MAN. + +In England during ten years (from 1857 to 1866) the average number of +children born alive yearly was 707,120, in the proportion of 104.5 males to +100 females. But in 1857 the male births throughout England were as 105.2, +and in 1865 as 104.0 to 100. Looking to separate districts, in +Buckinghamshire (where about 5000 children are annually born) the MEAN +proportion of male to female births, during the whole period of the above +ten years, was as 102.8 to 100; whilst in N. Wales (where the average +annual births are 12,873) it was as high as 106.2 to 100. Taking a still +smaller district, viz., Rutlandshire (where the annual births average only +739), in 1864 the male births were as 114.6, and in 1862 as only 97.0 to +100; but even in this small district the average of the 7385 births during +the whole ten years, was as 104.5 to 100: that is in the same ratio as +throughout England. (48. 'Twenty-ninth Annual Report of the Registrar- +General for 1866.' In this report (p. xii.) a special decennial table is +given.) The proportions are sometimes slightly disturbed by unknown +causes; thus Prof. Faye states "that in some districts of Norway there has +been during a decennial period a steady deficiency of boys, whilst in +others the opposite condition has existed." In France during forty-four +years the male to the female births have been as 106.2 to 100; but during +this period it has occurred five times in one department, and six times in +another, that the female births have exceeded the males. In Russia the +average proportion is as high as 108.9, and in Philadelphia in the United +States as 110.5 to 100. (49. For Norway and Russia, see abstract of Prof. +Faye's researches, in 'British and Foreign Medico-Chirurg. Review,' April +1867, pp. 343, 345. For France, the 'Annuaire pour l'An 1867,' p. 213. +For Philadelphia, Dr. Stockton Hough, 'Social Science Assoc.' 1874. For +the Cape of Good Hope, Quetelet as quoted by Dr. H.H. Zouteveen, in the +Dutch Translation of this work (vol. i. p. 417), where much information is +given on the proportion of the sexes.) The average for Europe, deduced by +Bickes from about seventy million births, is 106 males to 100 females. On +the other hand, with white children born at the Cape of Good Hope, the +proportion of males is so low as to fluctuate during successive years +between 90 and 99 males for every 100 females. It is a singular fact that +with Jews the proportion of male births is decidedly larger than with +Christians: thus in Prussia the proportion is as 113, in Breslau as 114, +and in Livonia as 120 to 100; the Christian births in these countries being +the same as usual, for instance, in Livonia as 104 to 100. (50. In regard +to the Jews, see M. Thury, 'La Loi de Production des Sexes,' 1863, p. 25.) + +Prof. Faye remarks that "a still greater preponderance of males would be +met with, if death struck both sexes in equal proportion in the womb and +during birth. But the fact is, that for every 100 still-born females, we +have in several countries from 134.6 to 144.9 still-born males. During the +first four or five years of life, also, more male children die than +females, for example in England, during the first year, 126 boys die for +every 100 girls--a proportion which in France is still more unfavourable." +(51. 'British and Foreign Medico-Chirurg. Review,' April 1867, p. 343. +Dr. Stark also remarks ('Tenth Annual Report of Births, Deaths, etc., in +Scotland,' 1867, p. xxviii.) that "These examples may suffice to show that, +at almost every stage of life, the males in Scotland have a greater +liability to death and a higher death-rate than the females. The fact, +however, of this peculiarity being most strongly developed at that +infantile period of life when the dress, food, and general treatment of +both sexes are alike, seems to prove that the higher male death-rate is an +impressed, natural, and constitutional peculiarity due to sex alone.") Dr. +Stockton Hough accounts for these facts in part by the more frequent +defective development of males than of females. We have before seen that +the male sex is more variable in structure than the female; and variations +in important organs would generally be injurious. But the size of the +body, and especially of the head, being greater in male than female infants +is another cause: for the males are thus more liable to be injured during +parturition. Consequently the still-born males are more numerous; and, as +a highly competent judge, Dr. Crichton Browne (52. 'West Riding Lunatic +Asylum Reports,' vol. i. 1871, p. 8. Sir J. Simpson has proved that the +head of the male infant exceeds that of the female by 3/8ths of an inch in +circumference, and by 1/8th in transverse diameter. Quetelet has shewn +that woman is born smaller than man; see Dr. Duncan, 'Fecundity, Fertility, +and Sterility,' 1871, p. 382.), believes, male infants often suffer in +health for some years after birth. Owing to this excess in the death-rate +of male children, both at birth and for some time subsequently, and owing +to the exposure of grown men to various dangers, and to their tendency to +emigrate, the females in all old-settled countries, where statistical +records have been kept, are found to preponderate considerably over the +males. (53. With the savage Guaranys of Paraguay, according to the +accurate Azara ('Voyages dans l'Amerique merid.' tom. ii. 1809, pp. 60, +179), the women are to the men in the proportion of 14 to 13.) + +It seems at first sight a mysterious fact that in different nations, under +different conditions and climates, in Naples, Prussia, Westphalia, Holland, +France, England and the United States, the excess of male over female +births is less when they are illegitimate than when legitimate. (54. +Babbage, 'Edinburgh Journal of Science,' 1829, vol. i. p. 88; also p. 90, +on still-born children. On illegitimate children in England, see 'Report +of Registrar-General for 1866,' p. xv.) This has been explained by +different writers in many different ways, as from the mothers being +generally young, from the large proportion of first pregnancies, etc. But +we have seen that male infants, from the large size of their heads, suffer +more than female infants during parturition; and as the mothers of +illegitimate children must be more liable than other women to undergo bad +labours, from various causes, such as attempts at concealment by tight +lacing, hard work, distress of mind, etc., their male infants would +proportionably suffer. And this probably is the most efficient of all the +causes of the proportion of males to females born alive being less amongst +illegitimate children than amongst the legitimate. With most animals the +greater size of the adult male than of the female, is due to the stronger +males having conquered the weaker in their struggles for the possession of +the females, and no doubt it is owing to this fact that the two sexes of at +least some animals differ in size at birth. Thus we have the curious fact +that we may attribute the more frequent deaths of male than female infants, +especially amongst the illegitimate, at least in part to sexual selection. + +It has often been supposed that the relative age of the two parents +determine the sex of the offspring; and Prof. Leuckart (55. Leuckart, in +Wagner 'Handwörterbuch der Phys.' B. iv. 1853, s. 774.) has advanced what +he considers sufficient evidence, with respect to man and certain +domesticated animals, that this is one important though not the sole factor +in the result. So again the period of impregnation relatively to the state +of the female has been thought by some to be the efficient cause; but +recent observations discountenance this belief. According to Dr. Stockton +Hough (56. 'Social Science Association of Philadelphia,' 1874.), the +season of the year, the poverty or wealth of the parents, residence in the +country or in cities, the crossing of foreign immigrants, etc., all +influence the proportion of the sexes. With mankind, polygamy has also +been supposed to lead to the birth of a greater proportion of female +infants; but Dr. J. Campbell (57. 'Anthropological Review,' April 1870, p. +cviii.) carefully attended to this subject in the harems of Siam, and +concludes that the proportion of male to female births is the same as from +monogamous unions. Hardly any animal has been rendered so highly +polygamous as the English race-horse, and we shall immediately see that his +male and female offspring are almost exactly equal in number. I will now +give the facts which I have collected with respect to the proportional +numbers of the sexes of various animals; and will then briefly discuss how +far selection has come into play in determining the result. + +HORSES. + +Mr. Tegetmeier has been so kind as to tabulate for me from the 'Racing +Calendar' the births of race-horses during a period of twenty-one years, +viz., from 1846 to 1867; 1849 being omitted, as no returns were that year +published. The total births were 25,560 (58. During eleven years a record +was kept of the number of mares which proved barren or prematurely slipped +their foals; and it deserves notice, as shewing how infertile these highly- +nurtured and rather closely-interbred animals have become, that not far +from one-third of the mares failed to produce living foals. Thus during +1866, 809 male colts and 816 female colts were born, and 743 mares failed +to produce offspring. During 1867, 836 males and 902 females were born, +and 794 mares failed.), consisting of 12,763 males and 12,797 females, or +in the proportion of 99.7 males to 100 females. As these numbers are +tolerably large, and as they are drawn from all parts of England, during +several years, we may with much confidence conclude that with the domestic +horse, or at least with the race-horse, the two sexes are produced in +almost equal numbers. The fluctuations in the proportions during +successive years are closely like those which occur with mankind, when a +small and thinly-populated area is considered; thus in 1856 the male horses +were as 107.1, and in 1867 as only 92.6 to 100 females. In the tabulated +returns the proportions vary in cycles, for the males exceeded the females +during six successive years; and the females exceeded the males during two +periods each of four years; this, however, may be accidental; at least I +can detect nothing of the kind with man in the decennial table in the +Registrar's Report for 1866. + +DOGS. + +During a period of twelve years, from 1857 to 1868, the births of a large +number of greyhounds, throughout England, were sent to the 'Field' +newspaper; and I am again indebted to Mr. Tegetmeier for carefully +tabulating the results. The recorded births were 6878, consisting of 3605 +males and 3273 females, that is, in the proportion of 110.1 males to 100 +females. The greatest fluctuations occurred in 1864, when the proportion +was as 95.3 males, and in 1867, as 116.3 males to 100 females. The above +average proportion of 110.1 to 100 is probably nearly correct in the case +of the greyhound, but whether it would hold with other domesticated breeds +is in some degree doubtful. Mr. Cupples has enquired from several great +breeders of dogs, and finds that all without exception believe that females +are produced in excess; but he suggests that this belief may have arisen +from females being less valued, and from the consequent disappointment +producing a stronger impression on the mind. + +SHEEP. + +The sexes of sheep are not ascertained by agriculturists until several +months after birth, at the period when the males are castrated; so that the +following returns do not give the proportions at birth. Moreover, I find +that several great breeders in Scotland, who annually raise some thousand +sheep, are firmly convinced that a larger proportion of males than of +females die during the first year or two. Therefore the proportion of +males would be somewhat larger at birth than at the age of castration. +This is a remarkable coincidence with what, as we have seen, occurs with +mankind, and both cases probably depend on the same cause. I have received +returns from four gentlemen in England who have bred Lowland sheep, chiefly +Leicesters, during the last ten to sixteen years; they amount altogether to +8965 births, consisting of 4407 males and 4558 females; that is in the +proportion of 96.7 males to 100 females. With respect to Cheviot and +black-faced sheep bred in Scotland, I have received returns from six +breeders, two of them on a large scale, chiefly for the years 1867-1869, +but some of the returns extend back to 1862. The total number recorded +amounts to 50,685, consisting of 25,071 males and 25,614 females or in the +proportion of 97.9 males to 100 females. If we take the English and Scotch +returns together, the total number amounts to 59,650, consisting of 29,478 +males and 30,172 females, or as 97.7 to 100. So that with sheep at the age +of castration the females are certainly in excess of the males, but +probably this would not hold good at birth. (59. I am much indebted to +Mr. Cupples for having procured for me the above returns from Scotland, as +well as some of the following returns on cattle. Mr. R. Elliot, of +Laighwood, first called my attention to the premature deaths of the males, +--a statement subsequently confirmed by Mr. Aitchison and others. To this +latter gentleman, and to Mr. Payan, I owe my thanks for large returns as to +sheep.) + +Of CATTLE I have received returns from nine gentlemen of 982 births, too +few to be trusted; these consisted of 477 bull-calves and 505 cow-calves; +i.e., in the proportion of 94.4 males to 100 females. The Rev. W.D. Fox +informs me that in 1867 out of 34 calves born on a farm in Derbyshire only +one was a bull. Mr. Harrison Weir has enquired from several breeders of +PIGS, and most of them estimate the male to the female births as about 7 to +6. This same gentleman has bred RABBITS for many years, and has noticed +that a far greater number of bucks are produced than does. But estimations +are of little value. + +Of mammalia in a state of nature I have been able to learn very little. In +regard to the common rat, I have received conflicting statements. Mr. R. +Elliot, of Laighwood, informs me that a rat-catcher assured him that he had +always found the males in great excess, even with the young in the nest. +In consequence of this, Mr. Elliot himself subsequently examined some +hundred old ones, and found the statement true. Mr. F. Buckland has bred a +large number of white rats, and he also believes that the males greatly +exceed the females. In regard to Moles, it is said that "the males are +much more numerous than the females" (60. Bell, 'History of British +Quadrupeds,' p. 100.): and as the catching of these animals is a special +occupation, the statement may perhaps be trusted. Sir A. Smith, in +describing an antelope of S. Africa (61. 'Illustrations of the Zoology of +S. Africa,' 1849, pl. 29.) (Kobus ellipsiprymnus), remarks, that in the +herds of this and other species, the males are few in number compared with +the females: the natives believe that they are born in this proportion; +others believe that the younger males are expelled from the herds, and Sir +A. Smith says, that though he has himself never seen herds consisting of +young males alone, others affirm that this does occur. It appears probable +that the young when expelled from the herd, would often fall a prey to the +many beasts of prey of the country. + +BIRDS. + +With respect to the FOWL, I have received only one account, namely, that +out of 1001 chickens of a highly-bred stock of Cochins, reared during eight +years by Mr. Stretch, 487 proved males and 514 females; i.e., as 94.7 to +100. In regard to domestic pigeons there is good evidence either that the +males are produced in excess, or that they live longer; for these birds +invariably pair, and single males, as Mr. Tegetmeier informs me, can always +be purchased cheaper than females. Usually the two birds reared from the +two eggs laid in the same nest are a male and a female; but Mr. Harrison +Weir, who has been so large a breeder, says that he has often bred two +cocks from the same nest, and seldom two hens; moreover, the hen is +generally the weaker of the two, and more liable to perish. + +With respect to birds in a state of nature, Mr. Gould and others (62. +Brehm ('Thierleben,' B. iv. s. 990) comes to the same conclusion.) are +convinced that the males are generally the more numerous; and as the young +males of many species resemble the females, the latter would naturally +appear to be the more numerous. Large numbers of pheasants are reared by +Mr. Baker of Leadenhall from eggs laid by wild birds, and he informs Mr. +Jenner Weir that four or five males to one female are generally produced. +An experienced observer remarks (63. On the authority of L. Lloyd, 'Game +Birds of Sweden,' 1867, pp. 12, 132.), that in Scandinavia the broods of +the capercailzie and black-cock contain more males than females; and that +with the Dal-ripa (a kind of ptarmigan) more males than females attend the +leks or places of courtship; but this latter circumstance is accounted for +by some observers by a greater number of hen birds being killed by vermin. +From various facts given by White of Selborne (64. 'Nat. Hist. of +Selborne,' letter xxix. edit. of 1825, vol. i. p. 139.), it seems clear +that the males of the partridge must be in considerable excess in the south +of England; and I have been assured that this is the case in Scotland. Mr. +Weir on enquiring from the dealers, who receive at certain seasons large +numbers of ruffs (Machetes pugnax), was told that the males are much the +more numerous. This same naturalist has also enquired for me from the +birdcatchers, who annually catch an astonishing number of various small +species alive for the London market, and he was unhesitatingly answered by +an old and trustworthy man, that with the chaffinch the males are in large +excess: he thought as high as 2 males to 1 female, or at least as high as +5 to 3. (65. Mr. Jenner Weir received similar information, on making +enquiries during the following year. To shew the number of living +chaffinches caught, I may mention that in 1869 there was a match between +two experts, and one man caught in a day 62, and another 40, male +chaffinches. The greatest number ever caught by one man in a single day +was 70.) The males of the blackbird, he likewise maintained, were by far +the more numerous, whether caught by traps or by netting at night. These +statements may apparently be trusted, because this same man said that the +sexes are about equal with the lark, the twite (Linaria montana), and +goldfinch. On the other hand, he is certain that with the common linnet, +the females preponderate greatly, but unequally during different years; +during some years he has found the females to the males as four to one. It +should, however, be borne in mind, that the chief season for catching birds +does not begin till September, so that with some species partial migrations +may have begun, and the flocks at this period often consist of hens alone. +Mr. Salvin paid particular attention to the sexes of the humming-birds in +Central America, and is convinced that with most of the species the males +are in excess; thus one year he procured 204 specimens belonging to ten +species, and these consisted of 166 males and of only 38 females. With two +other species the females were in excess: but the proportions apparently +vary either during different seasons or in different localities; for on one +occasion the males of Campylopterus hemileucurus were to the females as 5 +to 2, and on another occasion (66. 'Ibis,' vol. ii. p. 260, as quoted in +Gould's 'Trochilidae,' 1861, p. 52. For the foregoing proportions, I am +indebted to Mr. Salvin for a table of his results.) in exactly the reversed +ratio. As bearing on this latter point, I may add, that Mr. Powys found in +Corfu and Epirus the sexes of the chaffinch keeping apart, and "the females +by far the most numerous"; whilst in Palestine Mr. Tristram found "the male +flocks appearing greatly to exceed the female in number." (67. 'Ibis,' +1860, p. 137; and 1867, p. 369.) So again with the Quiscalus major, Mr. G. +Taylor says, that in Florida there were "very few females in proportion to +the males," (68. 'Ibis,' 1862, p. 187.) whilst in Honduras the proportion +was the other way, the species there having the character of a polygamist. + +FISH. + +With fish the proportional numbers of the sexes can be ascertained only by +catching them in the adult or nearly adult state; and there are many +difficulties in arriving at any just conclusion. (69. Leuckart quotes +Bloch (Wagner, 'Handwörterbuch der Phys.' B. iv. 1853, s. 775), that with +fish there are twice as many males as females.) Infertile females might +readily be mistaken for males, as Dr. Gunther has remarked to me in regard +to trout. With some species the males are believed to die soon after +fertilising the ova. With many species the males are of much smaller size +than the females, so that a large number of males would escape from the +same net by which the females were caught. M. Carbonnier (70. Quoted in +the 'Farmer,' March 18, 1869, p. 369.), who has especially attended to the +natural history of the pike (Esox lucius), states that many males, owing to +their small size, are devoured by the larger females; and he believes that +the males of almost all fish are exposed from this same cause to greater +danger than the females. Nevertheless, in the few cases in which the +proportional numbers have been actually observed, the males appear to be +largely in excess. Thus Mr. R. Buist, the superintendent of the +Stormontfield experiments, says that in 1865, out of 70 salmon first landed +for the purpose of obtaining the ova, upwards of 60 were males. In 1867 he +again "calls attention to the vast disproportion of the males to the +females. We had at the outset at least ten males to one female." +Afterwards females sufficient for obtaining ova were procured. He adds, +"from the great proportion of the males, they are constantly fighting and +tearing each other on the spawning-beds." (71. 'The Stormontfield +Piscicultural Experiments,' 1866, p. 23. The 'Field' newspaper, June 29, +1867.) This disproportion, no doubt, can be accounted for in part, but +whether wholly is doubtful, by the males ascending the rivers before the +females. Mr. F. Buckland remarks in regard to trout, that "it is a curious +fact that the males preponderate very largely in number over the females. +It INVARIABLY happens that when the first rush of fish is made to the net, +there will be at least seven or eight males to one female found captive. I +cannot quite account for this; either the males are more numerous than the +females, or the latter seek safety by concealment rather than flight." He +then adds, that by carefully searching the banks sufficient females for +obtaining ova can be found. (72. 'Land and Water,' 1868, p. 41.) Mr. H. +Lee informs me that out of 212 trout, taken for this purpose in Lord +Portsmouth's park, 150 were males and 62 females. + +The males of the Cyprinidae likewise seem to be in excess; but several +members of this Family, viz., the carp, tench, bream and minnow, appear +regularly to follow the practice, rare in the animal kingdom, of polyandry; +for the female whilst spawning is always attended by two males, one on each +side, and in the case of the bream by three or four males. This fact is so +well known, that it is always recommended to stock a pond with two male +tenches to one female, or at least with three males to two females. With +the minnow, an excellent observer states, that on the spawning-beds the +males are ten times as numerous as the females; when a female comes amongst +the males, "she is immediately pressed closely by a male on each side; and +when they have been in that situation for a time, are superseded by other +two males." (73. Yarrell, 'Hist. British Fishes,' vol. i. 1826, p. 307; +on the Cyprinus carpio, p. 331; on the Tinca vulgaris, p. 331; on the +Abramis brama, p. 336. See, for the minnow (Leuciscus phoxinus), 'Loudon's +Magazine of Natural History,' vol. v. 1832, p. 682.) + +INSECTS. + +In this great Class, the Lepidoptera almost alone afford means for judging +of the proportional numbers of the sexes; for they have been collected with +special care by many good observers, and have been largely bred from the +egg or caterpillar state. I had hoped that some breeders of silk-moths +might have kept an exact record, but after writing to France and Italy, and +consulting various treatises, I cannot find that this has ever been done. +The general opinion appears to be that the sexes are nearly equal, but in +Italy, as I hear from Professor Canestrini, many breeders are convinced +that the females are produced in excess. This same naturalist, however, +informs me, that in the two yearly broods of the Ailanthus silk-moth +(Bombyx cynthia), the males greatly preponderate in the first, whilst in +the second the two sexes are nearly equal, or the females rather in excess. + +In regard to Butterflies in a state of nature, several observers have been +much struck by the apparently enormous preponderance of the males. (74. +Leuckart quotes Meinecke (Wagner, 'Handwörterbuch der Phys.' B. iv. 1853, +s. 775) that the males of Butterflies are three or four times as numerous +as the females.) Thus Mr. Bates (75. 'The Naturalist on the Amazons,' +vol. ii. 1863, pp. 228, 347.), in speaking of several species, about a +hundred in number, which inhabit the upper Amazons, says that the males are +much more numerous than the females, even in the proportion of a hundred to +one. In North America, Edwards, who had great experience, estimates in the +genus Papilio the males to the females as four to one; and Mr. Walsh, who +informed me of this statement, says that with P. turnus this is certainly +the case. In South Africa, Mr. R. Trimen found the males in excess in 19 +species (76. Four of these cases are given by Mr. Trimen in his +'Rhopalocera Africae Australis.'); and in one of these, which swarms in +open places, he estimated the number of males as fifty to one female. With +another species, in which the males are numerous in certain localities, he +collected only five females during seven years. In the island of Bourbon, +M. Maillard states that the males of one species of Papilio are twenty +times as numerous as the females. (77. Quoted by Trimen, 'Transactions of +the Ent. Society,' vol. v. part iv. 1866, p. 330.) Mr. Trimen informs me +that as far as he has himself seen, or heard from others, it is rare for +the females of any butterfly to exceed the males in number; but three South +African species perhaps offer an exception. Mr. Wallace (78. +'Transactions, Linnean Society,' vol. xxv. p. 37.) states that the females +of Ornithoptera croesus, in the Malay archipelago, are more common and more +easily caught than the males; but this is a rare butterfly. I may here +add, that in Hyperythra, a genus of moths, Guenee says, that from four to +five females are sent in collections from India for one male. + +When this subject of the proportional numbers of the sexes of insects was +brought before the Entomological Society (79. 'Proceedings, Entomological +Society,' Feb. 17, 1868.), it was generally admitted that the males of most +Lepidoptera, in the adult or imago state, are caught in greater numbers +than the females: but this fact was attributed by various observers to the +more retiring habits of the females, and to the males emerging earlier from +the cocoon. This latter circumstance is well known to occur with most +Lepidoptera, as well as with other insects. So that, as M. Personnat +remarks, the males of the domesticated Bombyx Yamamai, are useless at the +beginning of the season, and the females at the end, from the want of +mates. (80. Quoted by Dr. Wallace in 'Proceedings, Entomological +Society,' 3rd series, vol. v. 1867, p. 487.) I cannot, however, persuade +myself that these causes suffice to explain the great excess of males, in +the above cases of certain butterflies which are extremely common in their +native countries. Mr. Stainton, who has paid very close attention during +many years to the smaller moths, informs me that when he collected them in +the imago state, he thought that the males were ten times as numerous as +the females, but that since he has reared them on a large scale from the +caterpillar state, he is convinced that the females are the more numerous. +Several entomologists concur in this view. Mr. Doubleday, however, and +some others, take an opposite view, and are convinced that they have reared +from the eggs and caterpillars a larger proportion of males than of +females. + +Besides the more active habits of the males, their earlier emergence from +the cocoon, and in some cases their frequenting more open stations, other +causes may be assigned for an apparent or real difference in the +proportional numbers of the sexes of Lepidoptera, when captured in the +imago state, and when reared from the egg or caterpillar state. I hear +from Professor Canestrini, that it is believed by many breeders in Italy, +that the female caterpillar of the silk-moth suffers more from the recent +disease than the male; and Dr. Staudinger informs me that in rearing +Lepidoptera more females die in the cocoon than males. With many species +the female caterpillar is larger than the male, and a collector would +naturally choose the finest specimens, and thus unintentionally collect a +larger number of females. Three collectors have told me that this was +their practice; but Dr. Wallace is sure that most collectors take all the +specimens which they can find of the rarer kinds, which alone are worth the +trouble of rearing. Birds when surrounded by caterpillars would probably +devour the largest; and Professor Canestrini informs me that in Italy some +breeders believe, though on insufficient evidence, that in the first broods +of the Ailanthus silk-moth, the wasps destroy a larger number of the female +than of the male caterpillars. Dr. Wallace further remarks that female +caterpillars, from being larger than the males, require more time for their +development, and consume more food and moisture: and thus they would be +exposed during a longer time to danger from ichneumons, birds, etc., and in +times of scarcity would perish in greater numbers. Hence it appears quite +possible that in a state of nature, fewer female Lepidoptera may reach +maturity than males; and for our special object we are concerned with their +relative numbers at maturity, when the sexes are ready to propagate their +kind. + +The manner in which the males of certain moths congregate in extraordinary +numbers round a single female, apparently indicates a great excess of +males, though this fact may perhaps be accounted for by the earlier +emergence of the males from their cocoons. Mr. Stainton informs me that +from twelve to twenty males, may often be seen congregated round a female +Elachista rufocinerea. It is well known that if a virgin Lasiocampa +quercus or Saturnia carpini be exposed in a cage, vast numbers of males +collect round her, and if confined in a room will even come down the +chimney to her. Mr. Doubleday believes that he has seen from fifty to a +hundred males of both these species attracted in the course of a single day +by a female in confinement. In the Isle of Wight Mr. Trimen exposed a box +in which a female of the Lasiocampa had been confined on the previous day, +and five males soon endeavoured to gain admittance. In Australia, Mr. +Verreaux, having placed the female of a small Bombyx in a box in his +pocket, was followed by a crowd of males, so that about 200 entered the +house with him. (81. Blanchard, 'Metamorphoses, Moeurs des Insectes,' +1868, pp. 225-226.) + +Mr. Doubleday has called my attention to M. Staudinger's (82. +'Lepidopteren-Doubletten Liste,' Berlin, No. x. 1866.) list of Lepidoptera, +which gives the prices of the males and females of 300 species or well- +marked varieties of butterflies (Rhopalocera). The prices for both sexes +of the very common species are of course the same; but in 114 of the rarer +species they differ; the males being in all cases, excepting one, the +cheaper. On an average of the prices of the 113 species, the price of the +male to that of the female is as 100 to 149; and this apparently indicates +that inversely the males exceed the females in the same proportion. About +2000 species or varieties of moths (Heterocera) are catalogued, those with +wingless females being here excluded on account of the difference in habits +between the two sexes: of these 2000 species, 141 differ in price +according to sex, the males of 130 being cheaper, and those of only 11 +being dearer than the females. The average price of the males of the 130 +species, to that of the females, is as 100 to 143. With respect to the +butterflies in this priced list, Mr. Doubleday thinks (and no man in +England has had more experience), that there is nothing in the habits of +the species which can account for the difference in the prices of the two +sexes, and that it can be accounted for only by an excess in the number of +the males. But I am bound to add that Dr. Staudinger informs me, that he +is himself of a different opinion. He thinks that the less active habits +of the females and the earlier emergence of the males will account for his +collectors securing a larger number of males than of females, and +consequently for the lower prices of the former. With respect to specimens +reared from the caterpillar-state, Dr. Staudinger believes, as previously +stated, that a greater number of females than of males die whilst confined +to the cocoons. He adds that with certain species one sex seems to +preponderate over the other during certain years. + +Of direct observations on the sexes of Lepidoptera, reared either from eggs +or caterpillars, I have received only the few following cases: (See +following table.) + +So that in these eight lots of cocoons and eggs, males were produced in +excess. Taken together the proportion of males is as 122.7 to 100 females. +But the numbers are hardly large enough to be trustworthy. + +On the whole, from these various sources of evidence, all pointing in the +same direction, I infer that with most species of Lepidoptera, the mature +males generally exceed the females in number, whatever the proportions may +be at their first emergence from the egg. + + Males Females + The Rev. J. Hellins* of Exeter reared, during + 1868, imagos of 73 species, which + consisted of 153 137 + + Mr. Albert Jones of Eltham reared, during + 1868, imagos of 9 species, which + consisted of 159 126 + + During 1869 he reared imagos from 4 species + consisting of 114 112 + + Mr. Buckler of Emsworth, Hants, during 1869, + reared imagos from 74 species, + consisting of 180 169 + + Dr. Wallace of Colchester reared from one + brood of Bombyx cynthia 52 48 + + Dr. Wallace raised, from cocoons of Bombyx + Pernyi sent from China, during 1869 224 123 + + Dr. Wallace raised, during 1868 and 1869, from + two lots of cocoons of Bombyx yamamai 52 46 + + Total 934 761 + +(*83. This naturalist has been so kind as to send me some results from +former years, in which the females seemed to preponderate; but so many of +the figures were estimates, that I found it impossible to tabulate them.) + +With reference to the other Orders of insects, I have been able to collect +very little reliable information. With the stag-beetle (Lucanus cervus) +"the males appear to be much more numerous than the females"; but when, as +Cornelius remarked during 1867, an unusual number of these beetles appeared +in one part of Germany, the females appeared to exceed the males as six to +one. With one of the Elateridae, the males are said to be much more +numerous than the females, and "two or three are often found united with +one female (84. Gunther's 'Record of Zoological Literature,' 1867, p. 260. +On the excess of female Lucanus, ibid, p. 250. On the males of Lucanus in +England, Westwood,' 'Modern Classification of Insects,' vol. i. p. 187. On +the Siagonium, ibid. p. 172.); so that here polyandry seems to prevail." +With Siagonium (Staphylinidae), in which the males are furnished with +horns, "the females are far more numerous than the opposite sex." Mr. +Janson stated at the Entomological Society that the females of the bark +feeding Tomicus villosus are so common as to be a plague, whilst the males +are so rare as to be hardly known. + +It is hardly worth while saying anything about the proportion of the sexes +in certain species and even groups of insects, for the males are unknown or +very rare, and the females are parthenogenetic, that is, fertile without +sexual union; examples of this are afforded by several of the Cynipidae. +(85. Walsh in 'The American Entomologist,' vol. i. 1869, p. 103. F. +Smith, 'Record of Zoological Lit.' 1867, p. 328.) In all the gall-making +Cynipidae known to Mr. Walsh, the females are four or five times as +numerous as the males; and so it is, as he informs me, with the gall-making +Cecidomyiidae (Diptera). With some common species of Saw-flies +(Tenthredinae) Mr. F. Smith has reared hundreds of specimens from larvae of +all sizes, but has never reared a single male; on the other hand, Curtis +says (86. 'Farm Insects,' pp. 45-46.), that with certain species +(Athalia), bred by him, the males were to the females as six to one; whilst +exactly the reverse occurred with the mature insects of the same species +caught in the fields. In the family of bees, Hermann Müller (87. +'Anwendung der Darwin'schen Lehre,' Verh. d. n. Jahrg., xxiv.), collected a +large number of specimens of many species, and reared others from the +cocoons, and counted the sexes. He found that the males of some species +greatly exceeded the females in number; in others the reverse occurred; and +in others the two sexes were nearly equal. But as in most cases the males +emerge from the cocoons before the females, they are at the commencement of +the breeding-season practically in excess. Müller also observed that the +relative number of the two sexes in some species differed much in different +localities. But as H. Müller has himself remarked to me, these remarks +must be received with some caution, as one sex might more easily escape +observation than the other. Thus his brother Fritz Müller has noticed in +Brazil that the two sexes of the same species of bee sometimes frequent +different kinds of flowers. With respect to the Orthoptera, I know hardly +anything about the relative number of the sexes: Korte (88. 'Die Strich, +Zug oder Wanderheuschrecke,' 1828, p. 20.), however, says that out of 500 +locusts which he examined, the males were to the females as five to six. +With the Neuroptera, Mr. Walsh states that in many, but by no means in all +the species of the Odonatous group, there is a great overplus of males: in +the genus Hetaerina, also, the males are generally at least four times as +numerous as the females. In certain species in the genus Gomphus the males +are equally in excess, whilst in two other species, the females are twice +or thrice as numerous as the males. In some European species of Psocus +thousands of females may be collected without a single male, whilst with +other species of the same genus both sexes are common. (89. 'Observations +on N. American Neuroptera,' by H. Hagen and B.D. Walsh, 'Proceedings, Ent. +Soc. Philadelphia,' Oct. 1863, pp. 168, 223, 239.) In England, Mr. +MacLachlan has captured hundreds of the female Apatania muliebris, but has +never seen the male; and of Boreus hyemalis only four or five males have +been seen here. (90. 'Proceedings, Ent. Soc. London,' Feb. 17, 1868.) +With most of these species (excepting the Tenthredinae) there is at present +no evidence that the females are subject to parthenogenesis; and thus we +see how ignorant we are of the causes of the apparent discrepancy in the +proportion of the two sexes. + +In the other classes of the Articulata I have been able to collect still +less information. With spiders, Mr. Blackwall, who has carefully attended +to this class during many years, writes to me that the males from their +more erratic habits are more commonly seen, and therefore appear more +numerous. This is actually the case with a few species; but he mentions +several species in six genera, in which the females appear to be much more +numerous than the males. (91. Another great authority with respect to +this class, Prof. Thorell of Upsala ('On European Spiders,' 1869-70, part +i. p. 205), speaks as if female spiders were generally commoner than the +males.) The small size of the males in comparison with the females (a +peculiarity which is sometimes carried to an extreme degree), and their +widely different appearance, may account in some instances for their rarity +in collections. (92. See, on this subject, Mr. O.P. Cambridge, as quoted +in 'Quarterly Journal of Science,' 1868, page 429.) + +Some of the lower Crustaceans are able to propagate their kind sexually, +and this will account for the extreme rarity of the males; thus von Siebold +(93. 'Beiträge zur Parthenogenesis,' p. 174.) carefully examined no less +than 13,000 specimens of Apus from twenty-one localities, and amongst these +he found only 319 males. With some other forms (as Tanais and Cypris), as +Fritz Müller informs me, there is reason to believe that the males are much +shorter-lived than the females; and this would explain their scarcity, +supposing the two sexes to be at first equal in number. On the other hand, +Müller has invariably taken far more males than females of the Diastylidae +and of Cypridina on the shores of Brazil: thus with a species in the +latter genus, 63 specimens caught the same day included 57 males; but he +suggests that this preponderance may be due to some unknown difference in +the habits of the two sexes. With one of the higher Brazilian crabs, +namely a Gelasimus, Fritz Müller found the males to be more numerous than +the females. According to the large experience of Mr. C. Spence Bate, the +reverse seems to be the case with six common British crabs, the names of +which he has given me. + +THE PROPORTION OF THE SEXES IN RELATION TO NATURAL SELECTION. + +There is reason to suspect that in some cases man has by selection +indirectly influenced his own sex-producing powers. Certain women tend to +produce during their whole lives more children of one sex than of the +other: and the same holds good of many animals, for instance, cows and +horses; thus Mr. Wright of Yeldersley House informs me that one of his Arab +mares, though put seven times to different horses, produced seven fillies. +Though I have very little evidence on this head, analogy would lead to the +belief, that the tendency to produce either sex would be inherited like +almost every other peculiarity, for instance, that of producing twins; and +concerning the above tendency a good authority, Mr. J. Downing, has +communicated to me facts which seem to prove that this does occur in +certain families of short-horn cattle. Col. Marshall (94. 'The Todas,' +1873, pp. 100, 111, 194, 196.) has recently found on careful examination +that the Todas, a hill-tribe of India, consist of 112 males and 84 females +of all ages--that is in a ratio of 133.3 males to 100 females. The Todas, +who are polyandrous in their marriages, during former times invariably +practised female infanticide; but this practice has now been discontinued +for a considerable period. Of the children born within late years, the +males are more numerous than the females, in the proportion of 124 to 100. +Colonel Marshall accounts for this fact in the following ingenious manner. +"Let us for the purpose of illustration take three families as representing +an average of the entire tribe; say that one mother gives birth to six +daughters and no sons; a second mother has six sons only, whilst the third +mother has three sons and three daughters. The first mother, following the +tribal custom, destroys four daughters and preserves two. The second +retains her six sons. The third kills two daughters and keeps one, as also +her three sons. We have then from the three families, nine sons and three +daughters, with which to continue the breed. But whilst the males belong +to families in which the tendency to produce sons is great, the females are +of those of a converse inclination. Thus the bias strengthens with each +generation, until, as we find, families grow to have habitually more sons +than daughters." + +That this result would follow from the above form of infanticide seems +almost certain; that is if we assume that a sex-producing tendency is +inherited. But as the above numbers are so extremely scanty, I have +searched for additional evidence, but cannot decide whether what I have +found is trustworthy; nevertheless the facts are, perhaps, worth giving. +The Maories of New Zealand have long practised infanticide; and Mr. Fenton +(95. 'Aboriginal Inhabitants of New Zealand: Government Report,' 1859, p. +36.) states that he "has met with instances of women who have destroyed +four, six, and even seven children, mostly females. However, the universal +testimony of those best qualified to judge, is conclusive that this custom +has for many years been almost extinct. Probably the year 1835 may be +named as the period of its ceasing to exist." Now amongst the New +Zealanders, as with the Todas, male births are considerably in excess. Mr. +Fenton remarks (p. 30), "One fact is certain, although the exact period of +the commencement of this singular condition of the disproportion of the +sexes cannot be demonstratively fixed, it is quite clear that this course +of decrease was in full operation during the years 1830 to 1844, when the +non-adult population of 1844 was being produced, and has continued with +great energy up to the present time." The following statements are taken +from Mr. Fenton (p. 26), but as the numbers are not large, and as the +census was not accurate, uniform results cannot be expected. It should be +borne in mind in this and the following cases, that the normal state of +every population is an excess of women, at least in all civilised +countries, chiefly owing to the greater mortality of the male sex during +youth, and partly to accidents of all kinds later in life. In 1858, the +native population of New Zealand was estimated as consisting of 31,667 +males and 24,303 females of all ages, that is in the ratio of 130.3 males +to 100 females. But during this same year, and in certain limited +districts, the numbers were ascertained with much care, and the males of +all ages were here 753 and the females 616; that is in the ratio of 122.2 +males to 100 females. It is more important for us that during this same +year of 1858, the NON-ADULT males within the same district were found to be +178, and the NON-ADULT females 142, that is in the ratio of 125.3 to 100. +It may be added that in 1844, at which period female infanticide had only +lately ceased, the NON-ADULT males in one district were 281, and the NON- +ADULT females only 194, that is in the ratio of 144.8 males to 100 females. + +In the Sandwich Islands, the males exceed the females in number. +Infanticide was formerly practised there to a frightful extent, but was by +no means confined to female infants, as is shewn by Mr. Ellis (96. +'Narrative of a Tour through Hawaii,' 1826, p. 298.), and as I have been +informed by Bishop Staley and the Rev. Mr. Coan. Nevertheless, another +apparently trustworthy writer, Mr. Jarves (97. 'History of the Sandwich +Islands,' 1843, p. 93.), whose observations apply to the whole archipelago, +remarks:--"Numbers of women are to be found, who confess to the murder of +from three to six or eight children," and he adds, "females from being +considered less useful than males were more often destroyed." From what is +known to occur in other parts of the world, this statement is probable; but +must be received with much caution. The practice of infanticide ceased +about the year 1819, when idolatry was abolished and missionaries settled +in the Islands. A careful census in 1839 of the adult and taxable men and +women in the island of Kauai and in one district of Oahu (Jarves, p. 404), +gives 4723 males and 3776 females; that is in the ratio of 125.08 to 100. +At the same time the number of males under fourteen years in Kauai and +under eighteen in Oahu was 1797, and of females of the same ages 1429; and +here we have the ratio of 125.75 males to 100 females. + +In a census of all the islands in 1850 (98. This is given in the Rev. H.T. +Cheever's 'Life in the Sandwich Islands,' 1851, p. 277.), the males of all +ages amount to 36,272, and the females to 33,128, or as 109.49 to 100. The +males under seventeen years amounted to 10,773, and the females under the +same age to 9593, or as 112.3 to 100. From the census of 1872, the +proportion of males of all ages (including half-castes) to females, is as +125.36 to 100. It must be borne in mind that all these returns for the +Sandwich Islands give the proportion of living males to living females, and +not of the births; and judging from all civilised countries the proportion +of males would have been considerably higher if the numbers had referred to +births. (99. Dr. Coulter, in describing ('Journal R. Geograph. Soc.' vol. +v. 1835, p. 67) the state of California about the year 1830, says that the +natives, reclaimed by the Spanish missionaries, have nearly all perished, +or are perishing, although well treated, not driven from their native land, +and kept from the use of spirits. He attributes this, in great part, to +the undoubted fact that the men greatly exceed the women in number; but he +does not know whether this is due to a failure of female offspring, or to +more females dying during early youth. The latter alternative, according +to all analogy, is very improbable. He adds that "infanticide, properly so +called, is not common, though very frequent recourse is had to abortion." +If Dr. Coulter is correct about infanticide, this case cannot be advanced +in support of Colonel Marshall's view. From the rapid decrease of the +reclaimed natives, we may suspect that, as in the cases lately given, their +fertility has been diminished from changed habits of life. + +I had hoped to gain some light on this subject from the breeding of dogs; +inasmuch as in most breeds, with the exception, perhaps, of greyhounds, +many more female puppies are destroyed than males, just as with the Toda +infants. Mr. Cupples assures me that this is usual with Scotch deer- +hounds. Unfortunately, I know nothing of the proportion of the sexes in +any breed, excepting greyhounds, and there the male births are to the +females as 110.1 to 100. Now from enquiries made from many breeders, it +seems that the females are in some respects more esteemed, though otherwise +troublesome; and it does not appear that the female puppies of the best- +bred dogs are systematically destroyed more than the males, though this +does sometimes take place to a limited extent. Therefore I am unable to +decide whether we can, on the above principles, account for the +preponderance of male births in greyhounds. On the other hand, we have +seen that with horses, cattle, and sheep, which are too valuable for the +young of either sex to be destroyed, if there is any difference, the +females are slightly in excess.) + +From the several foregoing cases we have some reason to believe that +infanticide practised in the manner above explained, tends to make a male- +producing race; but I am far from supposing that this practice in the case +of man, or some analogous process with other species, has been the sole +determining cause of an excess of males. There may be some unknown law +leading to this result in decreasing races, which have already become +somewhat infertile. Besides the several causes previously alluded to, the +greater facility of parturition amongst savages, and the less consequent +injury to their male infants, would tend to increase the proportion of +live-born males to females. There does not, however, seem to be any +necessary connection between savage life and a marked excess of males; that +is if we may judge by the character of the scanty offspring of the lately +existing Tasmanians and of the crossed offspring of the Tahitians now +inhabiting Norfolk Island. + +As the males and females of many animals differ somewhat in habits and are +exposed in different degrees to danger, it is probable that in many cases, +more of one sex than of the other are habitually destroyed. But as far as +I can trace out the complication of causes, an indiscriminate though large +destruction of either sex would not tend to modify the sex-producing power +of the species. With strictly social animals, such as bees or ants, which +produce a vast number of sterile and fertile females in comparison with the +males, and to whom this preponderance is of paramount importance, we can +see that those communities would flourish best which contained females +having a strong inherited tendency to produce more and more females; and in +such cases an unequal sex-producing tendency would be ultimately gained +through natural selection. With animals living in herds or troops, in +which the males come to the front and defend the herd, as with the bisons +of North America and certain baboons, it is conceivable that a male- +producing tendency might be gained by natural selection; for the +individuals of the better defended herds would leave more numerous +descendants. In the case of mankind the advantage arising from having a +preponderance of men in the tribe is supposed to be one chief cause of the +practice of female infanticide. + +In no case, as far as we can see, would an inherited tendency to produce +both sexes in equal numbers or to produce one sex in excess, be a direct +advantage or disadvantage to certain individuals more than to others; for +instance, an individual with a tendency to produce more males than females +would not succeed better in the battle for life than an individual with an +opposite tendency; and therefore a tendency of this kind could not be +gained through natural selection. Nevertheless, there are certain animals +(for instance, fishes and cirripedes) in which two or more males appear to +be necessary for the fertilisation of the female; and the males accordingly +largely preponderate, but it is by no means obvious how this male-producing +tendency could have been acquired. I formerly thought that when a tendency +to produce the two sexes in equal numbers was advantageous to the species, +it would follow from natural selection, but I now see that the whole +problem is so intricate that it is safer to leave its solution for the +future. + + +CHAPTER IX. + +SECONDARY SEXUAL CHARACTERS IN THE LOWER CLASSES OF THE ANIMAL KINGDOM. + +These characters absent in the lowest classes--Brilliant colours--Mollusca +--Annelids--Crustacea, secondary sexual characters strongly developed; +dimorphism; colour; characters not acquired before maturity--Spiders, +sexual colours of; stridulation by the males--Myriapoda. + +With animals belonging to the lower classes, the two sexes are not rarely +united in the same individual, and therefore secondary sexual characters +cannot be developed. In many cases where the sexes are separate, both are +permanently attached to some support, and the one cannot search or struggle +for the other. Moreover it is almost certain that these animals have too +imperfect senses and much too low mental powers to appreciate each other's +beauty or other attractions, or to feel rivalry. + +Hence in these classes or sub-kingdoms, such as the Protozoa, Coelenterata, +Echinodermata, Scolecida, secondary sexual characters, of the kind which we +have to consider, do not occur: and this fact agrees with the belief that +such characters in the higher classes have been acquired through sexual +selection, which depends on the will, desire, and choice of either sex. +Nevertheless some few apparent exceptions occur; thus, as I hear from Dr. +Baird, the males of certain Entozoa, or internal parasitic worms, differ +slightly in colour from the females; but we have no reason to suppose that +such differences have been augmented through sexual selection. +Contrivances by which the male holds the female, and which are +indispensable for the propagation of the species, are independent of sexual +selection, and have been acquired through ordinary selection. + +Many of the lower animals, whether hermaphrodites or with separate sexes, +are ornamented with the most brilliant tints, or are shaded and striped in +an elegant manner; for instance, many corals and sea-anemones (Actiniae), +some jelly-fish (Medusae, Porpita, etc.), some Planariae, many star-fishes, +Echini, Ascidians, etc.; but we may conclude from the reasons already +indicated, namely, the union of the two sexes in some of these animals, the +permanently affixed condition of others, and the low mental powers of all, +that such colours do not serve as a sexual attraction, and have not been +acquired through sexual selection. It should be borne in mind that in no +case have we sufficient evidence that colours have been thus acquired, +except where one sex is much more brilliantly or conspicuously coloured +than the other, and where there is no difference in habits between the +sexes sufficient to account for their different colours. But the evidence +is rendered as complete as it can ever be, only when the more ornamented +individuals, almost always the males, voluntarily display their attractions +before the other sex; for we cannot believe that such display is useless, +and if it be advantageous, sexual selection will almost inevitably follow. +We may, however, extend this conclusion to both sexes, when coloured alike, +if their colours are plainly analogous to those of one sex alone in certain +other species of the same group. + +How, then, are we to account for the beautiful or even gorgeous colours of +many animals in the lowest classes? It appears doubtful whether such +colours often serve as a protection; but that we may easily err on this +head, will be admitted by every one who reads Mr. Wallace's excellent essay +on this subject. It would not, for instance, at first occur to any one +that the transparency of the Medusae, or jelly-fish, is of the highest +service to them as a protection; but when we are reminded by Haeckel that +not only the Medusae, but many floating Mollusca, crustaceans, and even +small oceanic fishes partake of this same glass-like appearance, often +accompanied by prismatic colours, we can hardly doubt that they thus escape +the notice of pelagic birds and other enemies. M. Giard is also convinced +(1. 'Archives de Zoolog. Exper.' Oct. 1872, p. 563.) that the bright tints +of certain sponges and ascidians serve as a protection. Conspicuous +colours are likewise beneficial to many animals as a warning to their +would-be devourers that they are distasteful, or that they possess some +special means of defence; but this subject will be discussed more +conveniently hereafter. + +We can, in our ignorance of most of the lowest animals, only say that their +bright tints result either from the chemical nature or the minute structure +of their tissues, independently of any benefit thus derived. Hardly any +colour is finer than that of arterial blood; but there is no reason to +suppose that the colour of the blood is in itself any advantage; and though +it adds to the beauty of the maiden's cheek, no one will pretend that it +has been acquired for this purpose. So again with many animals, especially +the lower ones, the bile is richly coloured; thus, as I am informed by Mr. +Hancock, the extreme beauty of the Eolidae (naked sea-slugs) is chiefly due +to the biliary glands being seen through the translucent integuments--this +beauty being probably of no service to these animals. The tints of the +decaying leaves in an American forest are described by every one as +gorgeous; yet no one supposes that these tints are of the least advantage +to the trees. Bearing in mind how many substances closely analogous to +natural organic compounds have been recently formed by chemists, and which +exhibit the most splendid colours, it would have been a strange fact if +substances similarly coloured had not often originated, independently of +any useful end thus gained, in the complex laboratory of living organisms. + +THE SUB-KINGDOM OF THE MOLLUSCA. + +Throughout this great division of the animal kingdom, as far as I can +discover, secondary sexual characters, such as we are here considering, +never occur. Nor could they be expected in the three lowest classes, +namely, in the Ascidians, Polyzoa, and Brachiopods (constituting the +Molluscoida of some authors), for most of these animals are permanently +affixed to a support or have their sexes united in the same individual. In +the Lamellibranchiata, or bivalve shells, hermaphroditism is not rare. In +the next higher class of the Gasteropoda, or univalve shells, the sexes are +either united or separate. But in the latter case the males never possess +special organs for finding, securing, or charming the females, or for +fighting with other males. As I am informed by Mr. Gwyn Jeffreys, the sole +external difference between the sexes consists in the shell sometimes +differing a little in form; for instance, the shell of the male periwinkle +(Littorina littorea) is narrower and has a more elongated spire than that +of the female. But differences of this nature, it may be presumed, are +directly connected with the act of reproduction, or with the development of +the ova. + +The Gasteropoda, though capable of locomotion and furnished with imperfect +eyes, do not appear to be endowed with sufficient mental powers for the +members of the same sex to struggle together in rivalry, and thus to +acquire secondary sexual characters. Nevertheless with the pulmoniferous +gasteropods, or land-snails, the pairing is preceded by courtship; for +these animals, though hermaphrodites, are compelled by their structure to +pair together. Agassiz remarks, "Quiconque a eu l'occasion d'observer les +amours des limaçons, ne saurait mettre en doute la séduction deployée dans +les mouvements et les allures qui préparent et accomplissent le double +embrassement de ces hermaphrodites." (2. 'De l'Espèce et de la Class.' +etc., 1869, p. 106.) These animals appear also susceptible of some degree +of permanent attachment: an accurate observer, Mr. Lonsdale, informs me +that he placed a pair of land-snails, (Helix pomatia), one of which was +weakly, into a small and ill-provided garden. After a short time the +strong and healthy individual disappeared, and was traced by its track of +slime over a wall into an adjoining well-stocked garden. Mr. Lonsdale +concluded that it had deserted its sickly mate; but after an absence of +twenty-four hours it returned, and apparently communicated the result of +its successful exploration, for both then started along the same track and +disappeared over the wall. + +Even in the highest class of the Mollusca, the Cephalopoda or cuttle- +fishes, in which the sexes are separate, secondary sexual characters of the +present kind do not, as far as I can discover, occur. This is a surprising +circumstance, as these animals possess highly-developed sense-organs and +have considerable mental powers, as will be admitted by every one who has +watched their artful endeavours to escape from an enemy. (3. See, for +instance, the account which I have given in my 'Journal of Researches,' +1845, p. 7.) Certain Cephalopoda, however, are characterised by one +extraordinary sexual character, namely that the male element collects +within one of the arms or tentacles, which is then cast off, and clinging +by its sucking-discs to the female, lives for a time an independent life. +So completely does the cast-off arm resemble a separate animal, that it was +described by Cuvier as a parasitic worm under the name of Hectocotyle. But +this marvellous structure may be classed as a primary rather than as a +secondary sexual character. + +Although with the Mollusca sexual selection does not seem to have come into +play; yet many univalve and bivalve shells, such as volutes, cones, +scallops, etc., are beautifully coloured and shaped. The colours do not +appear in most cases to be of any use as a protection; they are probably +the direct result, as in the lowest classes, of the nature of the tissues; +the patterns and the sculpture of the shell depending on its manner of +growth. The amount of light seems to be influential to a certain extent; +for although, as repeatedly stated by Mr. Gwyn Jeffreys, the shells of some +species living at a profound depth are brightly coloured, yet we generally +see the lower surfaces, as well as the parts covered by the mantle, less +highly-coloured than the upper and exposed surfaces. (4. I have given +('Geological Observations on Volcanic Islands,' 1844, p. 53) a curious +instance of the influence of light on the colours of a frondescent +incrustation, deposited by the surf on the coast-rocks of Ascension and +formed by the solution of triturated sea-shells.) In some cases, as with +shells living amongst corals or brightly-tinted seaweeds, the bright +colours may serve as a protection. (5. Dr. Morse has lately discussed +this subject in his paper on the 'Adaptive Coloration of Mollusca,' 'Proc. +Boston Soc. of Nat. Hist.' vol. xiv. April 1871.) But that many of the +nudibranch Mollusca, or sea-slugs, are as beautifully coloured as any +shells, may be seen in Messrs. Alder and Hancock's magnificent work; and +from information kindly given me by Mr. Hancock, it seems extremely +doubtful whether these colours usually serve as a protection. With some +species this may be the case, as with one kind which lives on the green +leaves of algae, and is itself bright-green. But many brightly-coloured, +white, or otherwise conspicuous species, do not seek concealment; whilst +again some equally conspicuous species, as well as other dull-coloured +kinds live under stones and in dark recesses. So that with these +nudibranch molluscs, colour apparently does not stand in any close relation +to the nature of the places which they inhabit. + +These naked sea-slugs are hermaphrodites, yet they pair together, as do +land-snails, many of which have extremely pretty shells. It is conceivable +that two hermaphrodites, attracted by each other's greater beauty, might +unite and leave offspring which would inherit their parents' greater +beauty. But with such lowly-organised creatures this is extremely +improbable. Nor is it at all obvious how the offspring from the more +beautiful pairs of hermaphrodites would have any advantage over the +offspring of the less beautiful, so as to increase in number, unless indeed +vigour and beauty generally coincided. We have not here the case of a +number of males becoming mature before the females, with the more beautiful +males selected by the more vigorous females. If, indeed, brilliant colours +were beneficial to a hermaphrodite animal in relation to its general habits +of life, the more brightly-tinted individuals would succeed best and would +increase in number; but this would be a case of natural and not of sexual +selection. + +SUB-KINGDOM OF THE VERMES: CLASS, ANNELIDA (OR SEA-WORMS). + +In this class, although the sexes, when separate, sometimes differ from +each other in characters of such importance that they have been placed +under distinct genera or even families, yet the differences do not seem of +the kind which can be safely attributed to sexual selection. These animals +are often beautifully coloured, but as the sexes do not differ in this +respect, we are but little concerned with them. Even the Nemertians, +though so lowly organised, "vie in beauty and variety of colouring with any +other group in the invertebrate series"; yet Dr. McIntosh (6. See his +beautiful monograph on 'British Annelids,' part i. 1873, p. 3.) cannot +discover that these colours are of any service. The sedentary annelids +become duller-coloured, according to M. Quatrefages (7. See M. Perrier: +'L'Origine de l'Homme d'après Darwin,' 'Revue Scientifique', Feb. 1873, p. +866.), after the period of reproduction; and this I presume may be +attributed to their less vigorous condition at that time. All these worm- +like animals apparently stand too low in the scale for the individuals of +either sex to exert any choice in selecting a partner, or for the +individuals of the same sex to struggle together in rivalry. + +SUB-KINGDOM OF THE ARTHROPODA: CLASS, CRUSTACEA. + +In this great class we first meet with undoubted secondary sexual +characters, often developed in a remarkable manner. Unfortunately the +habits of crustaceans are very imperfectly known, and we cannot explain the +uses of many structures peculiar to one sex. With the lower parasitic +species the males are of small size, and they alone are furnished with +perfect swimming-legs, antennae and sense-organs; the females being +destitute of these organs, with their bodies often consisting of a mere +distorted mass. But these extraordinary differences between the two sexes +are no doubt related to their widely different habits of life, and +consequently do not concern us. In various crustaceans, belonging to +distinct families, the anterior antennae are furnished with peculiar +thread-like bodies, which are believed to act as smelling-organs, and these +are much more numerous in the males than in the females. As the males, +without any unusual development of their olfactory organs, would almost +certainly be able sooner or later to find the females, the increased number +of the smelling-threads has probably been acquired through sexual +selection, by the better provided males having been the more successful in +finding partners and in producing offspring. Fritz Müller has described a +remarkable dimorphic species of Tanais, in which the male is represented by +two distinct forms, which never graduate into each other. In the one form +the male is furnished with more numerous smelling-threads, and in the other +form with more powerful and more elongated chelae or pincers, which serve +to hold the female. Fritz Müller suggests that these differences between +the two male forms of the same species may have originated in certain +individuals having varied in the number of the smelling-threads, whilst +other individuals varied in the shape and size of their chelae; so that of +the former, those which were best able to find the female, and of the +latter, those which were best able to hold her, have left the greatest +number of progeny to inherit their respective advantages. (8. 'Facts and +Arguments for Darwin,' English translat., 1869, p. 20. See the previous +discussion on the olfactory threads. Sars has described a somewhat +analogous case (as quoted in 'Nature,' 1870, p. 455) in a Norwegian +crustacean, the Pontoporeia affinis.) + +[Fig.4. Labidocera Darwinii (from Lubbock). Labelled are: +a. Part of right anterior antenna of male, forming a prehensile organ. +b. Posterior pair of thoracic legs of male. +c. Ditto of female.] + +In some of the lower crustaceans, the right anterior antenna of the male +differs greatly in structure from the left, the latter resembling in its +simple tapering joints the antennae of the female. In the male the +modified antenna is either swollen in the middle or angularly bent, or +converted (Fig. 4) into an elegant, and sometimes wonderfully complex, +prehensile organ. (9. See Sir J. Lubbock in 'Annals and Mag. of Nat. +Hist.' vol. xi. 1853, pl. i. and x.; and vol. xii. (1853), pl. vii. See +also Lubbock in 'Transactions, Entomological Society,' vol. iv. new series, +1856-1858, p. 8. With respect to the zigzagged antennae mentioned below, +see Fritz Müller, 'Facts and Arguments for Darwin,' 1869, p. 40, foot- +note.) It serves, as I hear from Sir J. Lubbock, to hold the female, and +for this same purpose one of the two posterior legs (b) on the same side of +the body is converted into a forceps. In another family the inferior or +posterior antennae are "curiously zigzagged" in the males alone. + +[Fig. 5. Anterior part of body of Callianassa (from Milne-Edwards), +showing the unequal and differently-constructed right and left-hand chelae +of the male. N.B.--The artist by mistake has reversed the drawing, and +made the left-hand chela the largest. + +Fig. 6. Second leg of male Orchestia Tucuratinga (from Fritz Müller). + +Fig. 7. Ditto of female.] + +In the higher crustaceans the anterior legs are developed into chelae or +pincers; and these are generally larger in the male than in the female,--so +much so that the market value of the male edible crab (Cancer pagurus), +according to Mr. C. Spence Bate, is five times as great as that of the +female. In many species the chelae are of unequal size on the opposite +side of the body, the right-hand one being, as I am informed by Mr. Bate, +generally, though not invariably, the largest. This inequality is also +often much greater in the male than in the female. The two chelae of the +male often differ in structure (Figs. 5, 6, and 7), the smaller one +resembling that of the female. What advantage is gained by their +inequality in size on the opposite sides of the body, and by the inequality +being much greater in the male than in the female; and why, when they are +of equal size, both are often much larger in the male than in the female, +is not known. As I hear from Mr. Bate, the chelae are sometimes of such +length and size that they cannot possibly be used for carrying food to the +mouth. In the males of certain fresh-water prawns (Palaemon) the right leg +is actually longer than the whole body. (10. See a paper by Mr. C. Spence +Bate, with figures, in 'Proceedings, Zoological Society,' 1868, p. 363; and +on the nomenclature of the genus, ibid. p. 585. I am greatly indebted to +Mr. Spence Bate for nearly all the above statements with respect to the +chelae of the higher crustaceans.) The great size of the one leg with its +chelae may aid the male in fighting with his rivals; but this will not +account for their inequality in the female on the opposite sides of the +body. In Gelasimus, according to a statement quoted by Milne Edwards (11. +'Hist. Nat. des Crust.' tom. ii. 1837, p. 50.), the male and the female +live in the same burrow, and this shews that they pair; the male closes the +mouth of the burrow with one of its chelae, which is enormously developed; +so that here it indirectly serves as a means of defence. Their main use, +however, is probably to seize and to secure the female, and this in some +instances, as with Gammarus, is known to be the case. The male of the +hermit or soldier crab (Pagurus) for weeks together, carries about the +shell inhabited by the female. (12. Mr. C. Spence Bate, 'British +Association, Fourth Report on the Fauna of S. Devon.') The sexes, however, +of the common shore-crab (Carcinus maenas), as Mr. Bate informs me, unite +directly after the female has moulted her hard shell, when she is so soft +that she would be injured if seized by the strong pincers of the male; but +as she is caught and carried about by the male before moulting, she could +then be seized with impunity. + +[Fig.8. Orchestia Darwinii (from Fritz Müller), showing the differently- +constructed chelae of the two male forms.] + +Fritz Müller states that certain species of Melita are distinguished from +all other amphipods by the females having "the coxal lamellae of the +penultimate pair of feet produced into hook-like processes, of which the +males lay hold with the hands of the first pair." The development of these +hook-like processes has probably followed from those females which were the +most securely held during the act of reproduction, having left the largest +number of offspring. Another Brazilian amphipod (see Orchestia darwinii, +Fig. 8) presents a case of dimorphism, like that of Tanais; for there are +two male forms, which differ in the structure of their chelae. (13. Fritz +Müller, 'Facts and Arguments for Darwin,' 1869, pp. 25-28.) As either +chela would certainly suffice to hold the female,--for both are now used +for this purpose,--the two male forms probably originated by some having +varied in one manner and some in another; both forms having derived certain +special, but nearly equal advantages, from their differently shaped organs. + +It is not known that male crustaceans fight together for the possession of +the females, but it is probably the case; for with most animals when the +male is larger than the female, he seems to owe his greater size to his +ancestors having fought with other males during many generations. In most +of the orders, especially in the highest or the Brachyura, the male is +larger than the female; the parasitic genera, however, in which the sexes +follow different habits of life, and most of the Entomostraca must be +excepted. The chelae of many crustaceans are weapons well adapted for +fighting. Thus when a Devil-crab (Portunus puber) was seen by a son of Mr. +Bate fighting with a Carcinus maenas, the latter was soon thrown on its +back, and had every limb torn from its body. When several males of a +Brazilian Gelasimus, a species furnished with immense pincers, were placed +together in a glass vessel by Fritz Müller, they mutilated and killed one +another. Mr. Bate put a large male Carcinus maenas into a pan of water, +inhabited by a female which was paired with a smaller male; but the latter +was soon dispossessed. Mr. Bate adds, "if they fought, the victory was a +bloodless one, for I saw no wounds." This same naturalist separated a male +sand-skipper (so common on our sea-shores), Gammarus marinus, from its +female, both of whom were imprisoned in the same vessel with many +individuals of the same species. The female, when thus divorced, soon +joined the others. After a time the male was put again into the same +vessel; and he then, after swimming about for a time, dashed into the +crowd, and without any fighting at once took away his wife. This fact +shews that in the Amphipoda, an order low in the scale, the males and +females recognise each other, and are mutually attached. + +The mental powers of the Crustacea are probably higher than at first sight +appears probable. Any one who tries to catch one of the shore-crabs, so +common on tropical coasts, will perceive how wary and alert they are. +There is a large crab (Birgus latro), found on coral islands, which makes a +thick bed of the picked fibres of the cocoa-nut, at the bottom of a deep +burrow. It feeds on the fallen fruit of this tree by tearing off the husk, +fibre by fibre; and it always begins at that end where the three eye-like +depressions are situated. It then breaks through one of these eyes by +hammering with its heavy front pincers, and turning round, extracts the +albuminous core with its narrow posterior pincers. But these actions are +probably instinctive, so that they would be performed as well by a young +animal as by an old one. The following case, however, can hardly be so +considered: a trustworthy naturalist, Mr. Gardner (14. 'Travels in the +Interior of Brazil,' 1846, p. 111. I have given, in my 'Journal of +Researches,' p. 463, an account of the habits of the Birgus.), whilst +watching a shore-crab (Gelasimus) making its burrow, threw some shells +towards the hole. One rolled in, and three other shells remained within a +few inches of the mouth. In about five minutes the crab brought out the +shell which had fallen in, and carried it away to a distance of a foot; it +then saw the three other shells lying near, and evidently thinking that +they might likewise roll in, carried them to the spot where it had laid the +first. It would, I think, be difficult to distinguish this act from one +performed by man by the aid of reason. + +Mr. Bate does not know of any well-marked case of difference of colour in +the two sexes of our British crustaceans, in which respect the sexes of the +higher animals so often differ. In some cases, however, the males and +females differ slightly in tint, but Mr. Bate thinks not more than may be +accounted for by their different habits of life, such as by the male +wandering more about, and being thus more exposed to the light. Dr. Power +tried to distinguish by colour the sexes of the several species which +inhabit the Mauritius, but failed, except with one species of Squilla, +probably S. stylifera, the male of which is described as being "of a +beautiful bluish-green," with some of the appendages cherry-red, whilst the +female is clouded with brown and grey, "with the red about her much less +vivid than in the male." (15. Mr. Ch. Fraser, in 'Proc. Zoolog. Soc.' +1869, p. 3. I am indebted to Mr. Bate for Dr. Power's statement.) In this +case, we may suspect the agency of sexual selection. From M. Bert's +observations on Daphnia, when placed in a vessel illuminated by a prism, we +have reason to believe that even the lowest crustaceans can distinguish +colours. With Saphirina (an oceanic genus of Entomostraca), the males are +furnished with minute shields or cell-like bodies, which exhibit beautiful +changing colours; these are absent in the females, and in both sexes of one +species. (16. Claus, 'Die freilebenden Copepoden,' 1863, s. 35.) It +would, however, be extremely rash to conclude that these curious organs +serve to attract the females. I am informed by Fritz Müller, that in the +female of a Brazilian species of Gelasimus, the whole body is of a nearly +uniform greyish-brown. In the male the posterior part of the cephalo- +thorax is pure white, with the anterior part of a rich green, shading into +dark brown; and it is remarkable that these colours are liable to change in +the course of a few minutes--the white becoming dirty grey or even black, +the green "losing much of its brilliancy." It deserves especial notice +that the males do not acquire their bright colours until they become +mature. They appear to be much more numerous than the females; they differ +also in the larger size of their chelae. In some species of the genus, +probably in all, the sexes pair and inhabit the same burrow. They are +also, as we have seen, highly intelligent animals. From these various +considerations it seems probable that the male in this species has become +gaily ornamented in order to attract or excite the female. + +It has just been stated that the male Gelasimus does not acquire his +conspicuous colours until mature and nearly ready to breed. This seems a +general rule in the whole class in respect to the many remarkable +structural differences between the sexes. We shall hereafter find the same +law prevailing throughout the great sub-kingdom of the Vertebrata; and in +all cases it is eminently distinctive of characters which have been +acquired through sexual selection. Fritz Müller (17. 'Facts and +Arguments,' etc., p. 79.) gives some striking instances of this law; thus +the male sand-hopper (Orchestia) does not, until nearly full grown, acquire +his large claspers, which are very differently constructed from those of +the female; whilst young, his claspers resemble those of the female. + +CLASS, ARACHNIDA (SPIDERS). + +The sexes do not generally differ much in colour, but the males are often +darker than the females, as may be seen in Mr. Blackwall's magnificent +work. (18. 'A History of the Spiders of Great Britain,' 1861-64. For the +following facts, see pp. 77, 88, 102.) In some species, however, the +difference is conspicuous: thus the female of Sparassus smaragdulus is +dullish green, whilst the adult male has the abdomen of a fine yellow, with +three longitudinal stripes of rich red. In certain species of Thomisus the +sexes closely resemble each other, in others they differ much; and +analogous cases occur in many other genera. It is often difficult to say +which of the two sexes departs most from the ordinary coloration of the +genus to which the species belong; but Mr. Blackwall thinks that, as a +general rule, it is the male; and Canestrini (19. This author has recently +published a valuable essay on the 'Caratteri sessuali secondarii degli +Arachnidi,' in the 'Atti della Soc. Veneto-Trentina di Sc. Nat. Padova,' +vol. i. Fasc. 3, 1873.) remarks that in certain genera the males can be +specifically distinguished with ease, but the females with great +difficulty. I am informed by Mr. Blackwall that the sexes whilst young +usually resemble each other; and both often undergo great changes in colour +during their successive moults, before arriving at maturity. In other +cases the male alone appears to change colour. Thus the male of the above +bright-coloured Sparassus at first resembles the female, and acquires his +peculiar tints only when nearly adult. Spiders are possessed of acute +senses, and exhibit much intelligence; as is well known, the females often +shew the strongest affection for their eggs, which they carry about +enveloped in a silken web. The males search eagerly for the females, and +have been seen by Canestrini and others to fight for possession of them. +This same author says that the union of the two sexes has been observed in +about twenty species; and he asserts positively that the female rejects +some of the males who court her, threatens them with open mandibles, and at +last after long hesitation accepts the chosen one. From these several +considerations, we may admit with some confidence that the well-marked +differences in colour between the sexes of certain species are the results +of sexual selection; though we have not here the best kind of evidence,-- +the display by the male of his ornaments. From the extreme variability of +colour in the male of some species, for instance of Theridion lineatum, it +would appear that these sexual characters of the males have not as yet +become well fixed. Canestrini draws the same conclusion from the fact that +the males of certain species present two forms, differing from each other +in the size and length of their jaws; and this reminds us of the above +cases of dimorphic crustaceans. + +The male is generally much smaller than the female, sometimes to an +extraordinary degree (20. Aug. Vinson ('Araneides des Iles de la Reunion,' +pl. vi. figs. 1 and 2) gives a good instance of the small size of the male, +in Epeira nigra. In this species, as I may add, the male is testaceous and +the female black with legs banded with red. Other even more striking cases +of inequality in size between the sexes have been recorded ('Quarterly +Journal of Science,' July 1868, p. 429); but I have not seen the original +accounts.), and he is forced to be extremely cautious in making his +advances, as the female often carries her coyness to a dangerous pitch. De +Geer saw a male that "in the midst of his preparatory caresses was seized +by the object of his attentions, enveloped by her in a web and then +devoured, a sight which, as he adds, filled him with horror and +indignation." (21. Kirby and Spence, 'Introduction to Entomology,' vol. +i. 1818, p. 280.) The Rev. O.P. Cambridge (22. 'Proceedings, Zoological +Society,' 1871, p. 621.) accounts in the following manner for the extreme +smallness of the male in the genus Nephila. "M. Vinson gives a graphic +account of the agile way in which the diminutive male escapes from the +ferocity of the female, by gliding about and playing hide and seek over her +body and along her gigantic limbs: in such a pursuit it is evident that +the chances of escape would be in favour of the smallest males, while the +larger ones would fall early victims; thus gradually a diminutive race of +males would be selected, until at last they would dwindle to the smallest +possible size compatible with the exercise of their generative functions,-- +in fact, probably to the size we now see them, i.e., so small as to be a +sort of parasite upon the female, and either beneath her notice, or too +agile and too small for her to catch without great difficulty." + +Westring has made the interesting discovery that the males of several +species of Theridion (23. Theridion (Asagena, Sund.) serratipes, 4- +punctatum et guttatum; see Westring, in Kroyer, 'Naturhist. Tidskrift,' +vol. iv. 1842-1843, p. 349; and vol. ii. 1846-1849, p. 342. See, also, for +other species, 'Araneae Suecicae,' p. 184.) have the power of making a +stridulating sound, whilst the females are mute. The apparatus consists of +a serrated ridge at the base of the abdomen, against which the hard hinder +part of the thorax is rubbed; and of this structure not a trace can be +detected in the females. It deserves notice that several writers, +including the well-known arachnologist Walckenaer, have declared that +spiders are attracted by music. (24. Dr. H.H. van Zouteveen, in his Dutch +translation of this work (vol. i. p. 444), has collected several cases.) +From the analogy of the Orthoptera and Homoptera, to be described in the +next chapter, we may feel almost sure that the stridulation serves, as +Westring also believes, to call or to excite the female; and this is the +first case known to me in the ascending scale of the animal kingdom of +sounds emitted for this purpose. (25. Hilgendorf, however, has lately +called attention to an analogous structure in some of the higher +crustaceans, which seems adapted to produce sound; see 'Zoological Record,' +1869, p. 603.) + +CLASS, MYRIAPODA. + +In neither of the two orders in this class, the millipedes and centipedes, +can I find any well-marked instances of such sexual differences as more +particularly concern us. In Glomeris limbata, however, and perhaps in some +few other species, the males differ slightly in colour from the females; +but this Glomeris is a highly variable species. In the males of the +Diplopoda, the legs belonging either to one of the anterior or of the +posterior segments of the body are modified into prehensile hooks which +serve to secure the female. In some species of Iulus the tarsi of the male +are furnished with membranous suckers for the same purpose. As we shall +see when we treat of Insects, it is a much more unusual circumstance, that +it is the female in Lithobius, which is furnished with prehensile +appendages at the extremity of her body for holding the male. (26. +Walckenaer et P. Gervais, 'Hist. Nat. des Insectes: Apteres,' tom. iv. +1847, pp. 17, 19, 68.) + + +CHAPTER X. + +SECONDARY SEXUAL CHARACTERS OF INSECTS. + +Diversified structures possessed by the males for seizing the females-- +Differences between the sexes, of which the meaning is not understood-- +Difference in size between the sexes--Thysanura--Diptera--Hemiptera-- +Homoptera, musical powers possessed by the males alone--Orthoptera, musical +instruments of the males, much diversified in structure; pugnacity; +colours--Neuroptera, sexual differences in colour--Hymenoptera, pugnacity +and odours--Coleoptera, colours; furnished with great horns, apparently as +an ornament; battles, stridulating organs generally common to both sexes. + +In the immense class of insects the sexes sometimes differ in their +locomotive-organs, and often in their sense-organs, as in the pectinated +and beautifully plumose antennae of the males of many species. In Chloeon, +one of the Ephemerae, the male has great pillared eyes, of which the female +is entirely destitute. (1. Sir J. Lubbock, 'Transact. Linnean Soc.' vol. +xxv, 1866, p. 484. With respect to the Mutillidae see Westwood, 'Modern +Class. of Insects,' vol. ii. p. 213.) The ocelli are absent in the females +of certain insects, as in the Mutillidae; and here the females are likewise +wingless. But we are chiefly concerned with structures by which one male +is enabled to conquer another, either in battle or courtship, through his +strength, pugnacity, ornaments, or music. The innumerable contrivances, +therefore, by which the male is able to seize the female, may be briefly +passed over. Besides the complex structures at the apex of the abdomen, +which ought perhaps to be ranked as primary organs (2. These organs in the +male often differ in closely-allied species, and afford excellent specific +characters. But their importance, from a functional point of view, as Mr. +R. MacLachlan has remarked to me, has probably been overrated. It has been +suggested, that slight differences in these organs would suffice to prevent +the intercrossing of well-marked varieties or incipient species, and would +thus aid in their development. That this can hardly be the case, we may +infer from the many recorded cases (see, for instance, Bronn, 'Geschichte +der Natur,' B. ii. 1843, s. 164; and Westwood, 'Transact. Ent. Soc.' vol. +iii. 1842, p. 195) of distinct species having been observed in union. Mr. +MacLachlan informs me (vide 'Stett. Ent. Zeitung,' 1867, s. 155) that when +several species of Phryganidae, which present strongly-pronounced +differences of this kind, were confined together by Dr. Aug. Meyer, THEY +COUPLED, and one pair produced fertile ova.), "it is astonishing," as Mr. +B.D. Walsh (3. 'The Practical Entomologist,' Philadelphia, vol. ii. May +1867, p 88.) has remarked, "how many different organs are worked in by +nature for the seemingly insignificant object of enabling the male to grasp +the female firmly." The mandibles or jaws are sometimes used for this +purpose; thus the male Corydalis cornutus (a neuropterous insect in some +degree allied to the Dragon flies, etc.) has immense curved jaws, many +times longer than those of the female; and they are smooth instead of being +toothed, so that he is thus enabled to seize her without injury. (4. Mr. +Walsh, ibid. p. 107.) One of the stag-beetles of North America (Lucanus +elaphus) uses his jaws, which are much larger than those of the female, for +the same purpose, but probably likewise for fighting. In one of the sand- +wasps (Ammophila) the jaws in the two sexes are closely alike, but are used +for widely different purposes: the males, as Professor Westwood observes, +"are exceedingly ardent, seizing their partners round the neck with their +sickle-shaped jaws" (5. 'Modern Classification of Insects,' vol. ii. 1840, +pp. 205, 206. Mr. Walsh, who called my attention to the double use of the +jaws, says that he has repeatedly observed this fact.); whilst the females +use these organs for burrowing in sand-banks and making their nests. + +[Fig. 9. Crabro cribrarius. Upper figure, male; lower figure, female.] + +The tarsi of the front-legs are dilated in many male beetles, or are +furnished with broad cushions of hairs; and in many genera of water-beetles +they are armed with a round flat sucker, so that the male may adhere to the +slippery body of the female. It is a much more unusual circumstance that +the females of some water-beetles (Dytiscus) have their elytra deeply +grooved, and in Acilius sulcatus thickly set with hairs, as an aid to the +male. The females of some other water-beetles (Hydroporus) have their +elytra punctured for the same purpose. (6. We have here a curious and +inexplicable case of dimorphism, for some of the females of four European +species of Dytiscus, and of certain species of Hydroporus, have their +elytra smooth; and no intermediate gradations between the sulcated or +punctured, and the quite smooth elytra have been observed. See Dr. H. +Schaum, as quoted in the 'Zoologist,' vols. v.-vi. 1847-48, p. 1896. Also +Kirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 305.) +In the male of Crabro cribrarius (Fig. 9), it is the tibia which is dilated +into a broad horny plate, with minute membraneous dots, giving to it a +singular appearance like that of a riddle. (7. Westwood, 'Modern Class.' +vol. ii. p. 193. The following statement about Penthe, and others in +inverted commas, are taken from Mr. Walsh, 'Practical Entomologist,' +Philadelphia, vol. iii. p. 88.) In the male of Penthe (a genus of beetles) +a few of the middle joints of the antennae are dilated and furnished on the +inferior surface with cushions of hair, exactly like those on the tarsi of +the Carabidae, "and obviously for the same end." In male dragon-flies, +"the appendages at the tip of the tail are modified in an almost infinite +variety of curious patterns to enable them to embrace the neck of the +female." Lastly, in the males of many insects, the legs are furnished with +peculiar spines, knobs or spurs; or the whole leg is bowed or thickened, +but this is by no means invariably a sexual character; or one pair, or all +three pairs are elongated, sometimes to an extravagant length. (8. Kirby +and Spence, 'Introduct.' etc., vol. iii. pp. 332-336.) + +[Fig. 10. Taphroderes distortus (much enlarged). Upper figure, male; +lower figure, female.] + +The sexes of many species in all the orders present differences, of which +the meaning is not understood. One curious case is that of a beetle (Fig. +10), the male of which has left mandible much enlarged; so that the mouth +is greatly distorted. In another Carabidous beetle, Eurygnathus (9. +'Insecta Maderensia,' 1854, page 20.), we have the case, unique as far as +known to Mr. Wollaston, of the head of the female being much broader and +larger, though in a variable degree, than that of the male. Any number of +such cases could be given. They abound in the Lepidoptera: one of the +most extraordinary is that certain male butterflies have their fore-legs +more or less atrophied, with the tibiae and tarsi reduced to mere +rudimentary knobs. The wings, also, in the two sexes often differ in +neuration (10. E. Doubleday, 'Annals and Mag. of Nat. Hist.' vol. i. 1848, +p. 379. I may add that the wings in certain Hymenoptera (see Shuckard, +'Fossorial Hymenoptera,' 1837, pp. 39-43) differ in neuration according to +sex.), and sometimes considerably in outline, as in the Aricoris epitus, +which was shewn to me in the British Museum by Mr. A. Butler. The males of +certain South American butterflies have tufts of hair on the margins of the +wings, and horny excrescences on the discs of the posterior pair. (11. +H.W. Bates, in 'Journal of Proc. Linn. Soc.' vol. vi. 1862, p. 74. Mr. +Wonfor's observations are quoted in 'Popular Science Review,' 1868, p. +343.) In several British butterflies, as shewn by Mr. Wonfor, the males +alone are in parts clothed with peculiar scales. + +The use of the bright light of the female glow-worm has been subject to +much discussion. The male is feebly luminous, as are the larvae and even +the eggs. It has been supposed by some authors that the light serves to +frighten away enemies, and by others to guide the male to the female. At +last, Mr. Belt (12. 'The Naturalist in Nicaragua,' 1874, pp. 316-320. On +the phosphorescence of the eggs, see 'Annals and Magazine of Natural +History,' Nov. 1871, p. 372.) appears to have solved the difficulty: he +finds that all the Lampyridae which he has tried are highly distasteful to +insectivorous mammals and birds. Hence it is in accordance with Mr. Bates' +view, hereafter to be explained, that many insects mimic the Lampyridae +closely, in order to be mistaken for them, and thus to escape destruction. +He further believes that the luminous species profit by being at once +recognised as unpalatable. It is probable that the same explanation may be +extended to the Elaters, both sexes of which are highly luminous. It is +not known why the wings of the female glow-worm have not been developed; +but in her present state she closely resembles a larva, and as larvae are +so largely preyed on by many animals, we can understand why she has been +rendered so much more luminous and conspicuous than the male; and why the +larvae themselves are likewise luminous. + +DIFFERENCE IN SIZE BETWEEN THE SEXES. + +With insects of all kinds the males are commonly smaller than the females; +and this difference can often be detected even in the larval state. So +considerable is the difference between the male and female cocoons of the +silk-moth (Bombyx mori), that in France they are separated by a particular +mode of weighing. (13. Robinet, 'Vers a Soie,' 1848, p. 207.) In the +lower classes of the animal kingdom, the greater size of the females seems +generally to depend on their developing an enormous number of ova; and this +may to a certain extent hold good with insects. But Dr. Wallace has +suggested a much more probable explanation. He finds, after carefully +attending to the development of the caterpillars of Bombyx cynthia and +yamamai, and especially to that of some dwarfed caterpillars reared from a +second brood on unnatural food, "that in proportion as the individual moth +is finer, so is the time required for its metamorphosis longer; and for +this reason the female, which is the larger and heavier insect, from having +to carry her numerous eggs, will be preceded by the male, which is smaller +and has less to mature." (14. 'Transact. Ent. Soc.' 3rd series, vol. v. +p. 486.) Now as most insects are short-lived, and as they are exposed to +many dangers, it would manifestly be advantageous to the female to be +impregnated as soon as possible. This end would be gained by the males +being first matured in large numbers ready for the advent of the females; +and this again would naturally follow, as Mr. A.R. Wallace has remarked +(15. 'Journal of Proc. Ent. Soc.' Feb. 4, 1867, p. lxxi.), through natural +selection; for the smaller males would be first matured, and thus would +procreate a large number of offspring which would inherit the reduced size +of their male parents, whilst the larger males from being matured later +would leave fewer offspring. + +There are, however, exceptions to the rule of male insects being smaller +than the females: and some of these exceptions are intelligible. Size and +strength would be an advantage to the males, which fight for the possession +of the females; and in these cases, as with the stag-beetle (Lucanus), the +males are larger than the females. There are, however, other beetles which +are not known to fight together, of which the males exceed the females in +size; and the meaning of this fact is not known; but in some of these +cases, as with the huge Dynastes and Megasoma, we can at least see that +there would be no necessity for the males to be smaller than the females, +in order to be matured before them, for these beetles are not short-lived, +and there would be ample time for the pairing of the sexes. So again, male +dragon-flies (Libellulidae) are sometimes sensibly larger, and never +smaller, than the females (16. For this and other statements on the size +of the sexes, see Kirby and Spence, ibid. vol. iii. p. 300; on the duration +of life in insects, see p. 344.); and as Mr. MacLachlan believes, they do +not generally pair with the females until a week or fortnight has elapsed, +and until they have assumed their proper masculine colours. But the most +curious case, shewing on what complex and easily-overlooked relations, so +trifling a character as difference in size between the sexes may depend, is +that of the aculeate Hymenoptera; for Mr. F. Smith informs me that +throughout nearly the whole of this large group, the males, in accordance +with the general rule, are smaller than the females, and emerge about a +week before them; but amongst the Bees, the males of Apis mellifica, +Anthidium manicatum, and Anthophora acervorum, and amongst the Fossores, +the males of the Methoca ichneumonides, are larger than the females. The +explanation of this anomaly is that a marriage flight is absolutely +necessary with these species, and the male requires great strength and size +in order to carry the female through the air. Increased size has here been +acquired in opposition to the usual relation between size and the period of +development, for the males, though larger, emerge before the smaller +females. + +We will now review the several Orders, selecting such facts as more +particularly concern us. The Lepidoptera (Butterflies and Moths) will be +retained for a separate chapter. + +ORDER, THYSANURA. + +The members of this lowly organised order are wingless, dull-coloured, +minute insects, with ugly, almost misshapen heads and bodies. Their sexes +do not differ, but they are interesting as shewing us that the males pay +sedulous court to the females even low down in the animal scale. Sir J. +Lubbock (17. 'Transact. Linnean Soc.' vol. xxvi. 1868, p. 296.) says: "it +is very amusing to see these little creatures (Smynthurus luteus) +coquetting together. The male, which is much smaller than the female, runs +round her, and they butt one another, standing face to face and moving +backward and forward like two playful lambs. Then the female pretends to +run away and the male runs after her with a queer appearance of anger, gets +in front and stands facing her again; then she turns coyly round, but he, +quicker and more active, scuttles round too, and seems to whip her with his +antennae; then for a bit they stand face to face, play with their antennae, +and seem to be all in all to one another." + +ORDER, DIPTERA (FLIES). + +The sexes differ little in colour. The greatest difference, known to Mr. +F. Walker, is in the genus Bibio, in which the males are blackish or quite +black, and the females obscure brownish-orange. The genus Elaphomyia, +discovered by Mr. Wallace (18. 'The Malay Archipelago,' vol. ii. 1869, p. +313.) in New Guinea, is highly remarkable, as the males are furnished with +horns, of which the females are quite destitute. The horns spring from +beneath the eyes, and curiously resemble those of a stag, being either +branched or palmated. In one of the species, they equal the whole body in +length. They might be thought to be adapted for fighting, but as in one +species they are of a beautiful pink colour, edged with black, with a pale +central stripe, and as these insects have altogether a very elegant +appearance, it is perhaps more probable that they serve as ornaments. That +the males of some Diptera fight together is certain; Prof. Westwood (19. +'Modern Classification of Insects,' vol. ii. 1840, p. 526.) has several +times seen this with the Tipulae. The males of other Diptera apparently +try to win the females by their music: H. Müller (20. 'Anwendung,' etc., +'Verh. d. n. V. Jahrg.' xxix. p. 80. Mayer, in 'American Naturalist,' +1874, p. 236.) watched for some time two males of an Eristalis courting a +female; they hovered above her, and flew from side to side, making a high +humming noise at the same time. Gnats and mosquitoes (Culicidae) also seem +to attract each other by humming; and Prof. Mayer has recently ascertained +that the hairs on the antennae of the male vibrate in unison with the notes +of a tuning-fork, within the range of the sounds emitted by the female. +The longer hairs vibrate sympathetically with the graver notes, and the +shorter hairs with the higher ones. Landois also asserts that he has +repeatedly drawn down a whole swarm of gnats by uttering a particular note. +It may be added that the mental faculties of the Diptera are probably +higher than in most other insects, in accordance with their highly- +developed nervous system. (21. See Mr. B.T. Lowne's interesting work, 'On +the Anatomy of the Blow-fly, Musca vomitoria,' 1870, p. 14. He remarks (p. +33) that, "the captured flies utter a peculiar plaintive note, and that +this sound causes other flies to disappear.") + +ORDER, HEMIPTERA (FIELD-BUGS). + +Mr. J.W. Douglas, who has particularly attended to the British species, has +kindly given me an account of their sexual differences. The males of some +species are furnished with wings, whilst the females are wingless; the +sexes differ in the form of their bodies, elytra, antennae and tarsi; but +as the signification of these differences are unknown, they may be here +passed over. The females are generally larger and more robust than the +males. With British, and, as far as Mr. Douglas knows, with exotic +species, the sexes do not commonly differ much in colour; but in about six +British species the male is considerably darker than the female, and in +about four other species the female is darker than the male. Both sexes of +some species are beautifully coloured; and as these insects emit an +extremely nauseous odour, their conspicuous colours may serve as a signal +that they are unpalatable to insectivorous animals. In some few cases +their colours appear to be directly protective: thus Prof. Hoffmann +informs me that he could hardly distinguish a small pink and green species +from the buds on the trunks of lime-trees, which this insect frequents. + +Some species of Reduvidae make a stridulating noise; and, in the case of +Pirates stridulus, this is said (22. Westwood, 'Modern Classification of +Insects,' vol. ii. p. 473.) to be effected by the movement of the neck +within the pro-thoracic cavity. According to Westring, Reduvius personatus +also stridulates. But I have no reason to suppose that this is a sexual +character, excepting that with non-social insects there seems to be no use +for sound-producing organs, unless it be as a sexual call. + +ORDER: HOMOPTERA. + +Every one who has wandered in a tropical forest must have been astonished +at the din made by the male Cicadae. The females are mute; as the Grecian +poet Xenarchus says, "Happy the Cicadas live, since they all have voiceless +wives." The noise thus made could be plainly heard on board the "Beagle," +when anchored at a quarter of a mile from the shore of Brazil; and Captain +Hancock says it can be heard at the distance of a mile. The Greeks +formerly kept, and the Chinese now keep these insects in cages for the sake +of their song, so that it must be pleasing to the ears of some men. (23. +These particulars are taken from Westwood's 'Modern Classification of +Insects,' vol. ii. 1840, p. 422. See, also, on the Fulgoridae, Kirby and +Spence, 'Introduct.' vol. ii. p. 401.) The Cicadidae usually sing during +the day, whilst the Fulgoridae appear to be night-songsters. The sound, +according to Landois (24. 'Zeitschrift für wissenschaft. Zoolog.' B. xvii. +1867, ss. 152-158.), is produced by the vibration of the lips of the +spiracles, which are set into motion by a current of air emitted from the +tracheae; but this view has lately been disputed. Dr. Powell appears to +have proved (25. 'Transactions of the New Zealand Institute,' vol. v. +1873, p. 286.) that it is produced by the vibration of a membrane, set into +action by a special muscle. In the living insect, whilst stridulating, +this membrane can be seen to vibrate; and in the dead insect the proper +sound is heard, if the muscle, when a little dried and hardened, is pulled +with the point of a pin. In the female the whole complex musical apparatus +is present, but is much less developed than in the male, and is never used +for producing sound. + +With respect to the object of the music, Dr. Hartman, in speaking of the +Cicada septemdecim of the United States, says (26. I am indebted to Mr. +Walsh for having sent me this extract from 'A Journal of the Doings of +Cicada septemdecim,' by Dr. Hartman.), "the drums are now (June 6th and +7th, 1851) heard in all directions. This I believe to be the marital +summons from the males. Standing in thick chestnut sprouts about as high +as my head, where hundreds were around me, I observed the females coming +around the drumming males." He adds, "this season (Aug. 1868) a dwarf +pear-tree in my garden produced about fifty larvae of Cic. pruinosa; and I +several times noticed the females to alight near a male while he was +uttering his clanging notes." Fritz Müller writes to me from S. Brazil +that he has often listened to a musical contest between two or three males +of a species with a particularly loud voice, seated at a considerable +distance from each other: as soon as one had finished his song, another +immediately began, and then another. As there is so much rivalry between +the males, it is probable that the females not only find them by their +sounds, but that, like female birds, they are excited or allured by the +male with the most attractive voice. + +I have not heard of any well-marked cases of ornamental differences between +the sexes of the Homoptera. Mr. Douglas informs me that there are three +British species, in which the male is black or marked with black bands, +whilst the females are pale-coloured or obscure. + +ORDER, ORTHOPTERA (CRICKETS AND GRASSHOPPERS). + +The males in the three saltatorial families in this Order are remarkable +for their musical powers, namely the Achetidae or crickets, the Locustidae +for which there is no equivalent English name, and the Acridiidae or +grasshoppers. The stridulation produced by some of the Locustidae is so +loud that it can be heard during the night at the distance of a mile (27. +L. Guilding, 'Transactions of the Linnean Society,' vol. xv. p. 154.); and +that made by certain species is not unmusical even to the human ear, so +that the Indians on the Amazons keep them in wicker cages. All observers +agree that the sounds serve either to call or excite the mute females. +With respect to the migratory locusts of Russia, Korte has given (28. I +state this on the authority of Koppen, 'Über die Heuschrecken in +Südrussland,' 1866, p. 32, for I have in vain endeavoured to procure +Korte's work.) an interesting case of selection by the female of a male. +The males of this species (Pachytylus migratorius) whilst coupled with the +female stridulate from anger or jealousy, if approached by other males. +The house-cricket when surprised at night uses its voice to warn its +fellows. (29. Gilbert White, 'Natural History of Selborne,' vol. ii. +1825, p. 262.) In North America the Katy-did (Platyphyllum concavum, one +of the Locustidae) is described (30. Harris, 'Insects of New England,' +1842, p. 128.) as mounting on the upper branches of a tree, and in the +evening beginning "his noisy babble, while rival notes issue from the +neighbouring trees, and the groves resound with the call of Katy-did-she- +did the live-long night." Mr. Bates, in speaking of the European field- +cricket (one of the Achetidae), says "the male has been observed to place +himself in the evening at the entrance of his burrow, and stridulate until +a female approaches, when the louder notes are succeeded by a more subdued +tone, whilst the successful musician caresses with his antennae the mate he +has won." (31. 'The Naturalist on the Amazons,' vol. i. 1863, p. 252. Mr. +Bates gives a very interesting discussion on the gradations in the musical +apparatus of the three families. See also Westwood, 'Modern Classification +of Insects,' vol. ii. pp. 445 and 453.) Dr. Scudder was able to excite one +of these insects to answer him, by rubbing on a file with a quill. (32. +'Proceedings of the Boston Society of Natural History,' vol. xi. April +1868.) In both sexes a remarkable auditory apparatus has been discovered +by Von Siebold, situated in the front legs. (33. 'Nouveau Manuel d'Anat. +Comp.' (French translat.), tom. 1, 1850, p. 567.) + +[Fig.11. Gryllus campestris (from Landois). +Right-hand figure, under side of part of a wing-nervure, much magnified, +showing the teeth, st. +Left-hand figure, upper surface of wing-cover, with the projecting, smooth +nervure, r, across which the teeth (st) are scraped. + +Fig.12. Teeth of Nervure of Gryllus domesticus (from Landois).] + +In the three Families the sounds are differently produced. In the males of +the Achetidae both wing-covers have the same apparatus; and this in the +field-cricket (see Gryllus campestris, Fig. 11) consists, as described by +Landois (34. 'Zeitschrift für wissenschaft. Zoolog.' B. xvii. 1867, s. +117.), of from 131 to 138 sharp, transverse ridges or teeth (st) on the +under side of one of the nervures of the wing-cover. This toothed nervure +is rapidly scraped across a projecting, smooth, hard nervure (r) on the +upper surface of the opposite wing. First one wing is rubbed over the +other, and then the movement is reversed. Both wings are raised a little +at the same time, so as to increase the resonance. In some species the +wing-covers of the males are furnished at the base with a talc-like plate. +(35. Westwood, 'Modern Classification of Insects,' vol. i. p. 440.) I +here give a drawing (Fig. 12) of the teeth on the under side of the nervure +of another species of Gryllus, viz., G. domesticus. With respect to the +formation of these teeth, Dr. Gruber has shewn (36. 'Ueber der Tonapparat +der Locustiden, ein Beitrag zum Darwinismus,' 'Zeitschrift für +wissenschaft. Zoolog.' B. xxii. 1872, p. 100.) that they have been +developed by the aid of selection, from the minute scales and hairs with +which the wings and body are covered, and I came to the same conclusion +with respect to those of the Coleoptera. But Dr. Gruber further shews that +their development is in part directly due to the stimulus from the friction +of one wing over the other. + +[Fig.13. Chlorocoelus Tanana (from Bates). +a,b. Lobes of opposite wing-covers.] + +In the Locustidae the opposite wing-covers differ from each other in +structure (Fig. 13), and the action cannot, as in the last family, be +reversed. The left wing, which acts as the bow, lies over the right wing +which serves as the fiddle. One of the nervures (a) on the under surface +of the former is finely serrated, and is scraped across the prominent +nervures on the upper surface of the opposite or right wing. In our +British Phasgonura viridissima it appeared to me that the serrated nervure +is rubbed against the rounded hind-corner of the opposite wing, the edge of +which is thickened, coloured brown, and very sharp. In the right wing, but +not in the left, there is a little plate, as transparent as talc, +surrounded by nervures, and called the speculum. In Ephippiger vitium, a +member of this same family, we have a curious subordinate modification; for +the wing-covers are greatly reduced in size, but "the posterior part of the +pro-thorax is elevated into a kind of dome over the wing-covers, and which +has probably the effect of increasing the sound." (37. Westwood 'Modern +Classification of Insects,' vol. i. p. 453.) + +We thus see that the musical apparatus is more differentiated or +specialised in the Locustidae (which include, I believe, the most powerful +performers in the Order), than in the Achetidae, in which both wing-covers +have the same structure and the same function. (38. Landois, 'Zeitschrift +für wissenschaft. Zoolog.' B. xvii. 1867, ss. 121, 122.) Landois, however, +detected in one of the Locustidae, namely in Decticus, a short and narrow +row of small teeth, mere rudiments, on the inferior surface of the right +wing-cover, which underlies the other and is never used as the bow. I +observed the same rudimentary structure on the under side of the right +wing-cover in Phasgonura viridissima. Hence we may infer with confidence +that the Locustidae are descended from a form, in which, as in the existing +Achetidae, both wing-covers had serrated nervures on the under surface, and +could be indifferently used as the bow; but that in the Locustidae the two +wing-covers gradually became differentiated and perfected, on the principle +of the division of labour, the one to act exclusively as the bow, and the +other as the fiddle. Dr. Gruber takes the same view, and has shewn that +rudimentary teeth are commonly found on the inferior surface of the right +wing. By what steps the more simple apparatus in the Achetidae originated, +we do not know, but it is probable that the basal portions of the wing- +covers originally overlapped each other as they do at present; and that the +friction of the nervures produced a grating sound, as is now the case with +the wing-covers of the females. (39. Mr. Walsh also informs me that he +has noticed that the female of the Platyphyllum concavum, "when captured +makes a feeble grating noise by shuffling her wing-covers together.") A +grating sound thus occasionally and accidentally made by the males, if it +served them ever so little as a love-call to the females, might readily +have been intensified through sexual selection, by variations in the +roughness of the nervures having been continually preserved. + +[Fig.14. Hind-leg of Stenobothrus pratorum: +r, the stridulating ridge; +lower figure, the teeth forming the ridge, much magnified (from Landois). + +Fig.15. Pneumora (from specimens in the British Museum). +Upper figure, male; +lower figure, female.] + +In the last and third family, namely the Acridiidae or grasshoppers, the +stridulation is produced in a very different manner, and according to Dr. +Scudder, is not so shrill as in the preceding Families. The inner surface +of the femur (Fig. 14, r) is furnished with a longitudinal row of minute, +elegant, lancet-shaped, elastic teeth, from 85 to 93 in number (40. +Landois, ibid. s. 113.); and these are scraped across the sharp, projecting +nervures on the wing-covers, which are thus made to vibrate and resound. +Harris (41. 'Insects of New England,' 1842, p. 133.) says that when one of +the males begins to play, he first "bends the shank of the hind-leg beneath +the thigh, where it is lodged in a furrow designed to receive it, and then +draws the leg briskly up and down. He does not play both fiddles together, +but alternately, first upon one and then on the other." In many species, +the base of the abdomen is hollowed out into a great cavity which is +believed to act as a resounding board. In Pneumora (Fig. 15), a S. African +genus belonging to the same family, we meet with a new and remarkable +modification; in the males a small notched ridge projects obliquely from +each side of the abdomen, against which the hind femora are rubbed. (42. +Westwood, 'Modern Classification,' vol i. p. 462.) As the male is +furnished with wings (the female being wingless), it is remarkable that the +thighs are not rubbed in the usual manner against the wing-covers; but this +may perhaps be accounted for by the unusually small size of the hind-legs. +I have not been able to examine the inner surface of the thighs, which, +judging from analogy, would be finely serrated. The species of Pneumora +have been more profoundly modified for the sake of stridulation than any +other orthopterous insect; for in the male the whole body has been +converted into a musical instrument, being distended with air, like a great +pellucid bladder, so as to increase the resonance. Mr. Trimen informs me +that at the Cape of Good Hope these insects make a wonderful noise during +the night. + +In the three foregoing families, the females are almost always destitute of +an efficient musical apparatus. But there are a few exceptions to this +rule, for Dr. Gruber has shewn that both sexes of Ephippiger vitium are +thus provided; though the organs differ in the male and female to a certain +extent. Hence we cannot suppose that they have been transferred from the +male to the female, as appears to have been the case with the secondary +sexual characters of many other animals. They must have been independently +developed in the two sexes, which no doubt mutually call to each other +during the season of love. In most other Locustidae (but not according to +Landois in Decticus) the females have rudiments of the stridulatory organs +proper to the male; from whom it is probable that these have been +transferred. Landois also found such rudiments on the under surface of the +wing-covers of the female Achetidae, and on the femora of the female +Acridiidae. In the Homoptera, also, the females have the proper musical +apparatus in a functionless state; and we shall hereafter meet in other +divisions of the animal kingdom with many instances of structures proper to +the male being present in a rudimentary condition of the female. + +Landois has observed another important fact, namely, that in the females of +the Acridiidae, the stridulating teeth on the femora remain throughout life +in the same condition in which they first appear during the larval state in +both sexes. In the males, on the other hand, they become further +developed, and acquire their perfect structure at the last moult, when the +insect is mature and ready to breed. + +From the facts now given, we see that the means by which the males of the +Orthoptera produce their sounds are extremely diversified, and are +altogether different from those employed by the Homoptera. (43. Landois +has recently found in certain Orthoptera rudimentary structures closely +similar to the sound-producing organs in the Homoptera; and this is a +surprising fact. See 'Zeitschrift für wissenschaft, Zoolog.' B. xxii. Heft +3, 1871, p. 348.) But throughout the animal kingdom we often find the same +object gained by the most diversified means; this seems due to the whole +organisation having undergone multifarious changes in the course of ages, +and as part after part varied different variations were taken advantage of +for the same general purpose. The diversity of means for producing sound +in the three families of the Orthoptera and in the Homoptera, impresses the +mind with the high importance of these structures to the males, for the +sake of calling or alluring the females. We need feel no surprise at the +amount of modification which the Orthoptera have undergone in this respect, +as we now know, from Dr. Scudder's remarkable discovery (44. +'Transactions, Entomological Society,' 3rd series, vol. ii. ('Journal of +Proceedings,' p. 117).), that there has been more than ample time. This +naturalist has lately found a fossil insect in the Devonian formation of +New Brunswick, which is furnished with "the well-known tympanum or +stridulating apparatus of the male Locustidae." The insect, though in most +respects related to the Neuroptera, appears, as is so often the case with +very ancient forms, to connect the two related Orders of the Neuroptera and +Orthoptera. + +I have but little more to say on the Orthoptera. Some of the species are +very pugnacious: when two male field-crickets (Gryllus campestris) are +confined together, they fight till one kills the other; and the species of +Mantis are described as manoeuvring with their sword-like front-limbs, like +hussars with their sabres. The Chinese keep these insects in little bamboo +cages, and match them like game-cocks. (45. Westwood, 'Modern +Classification of Insects,' vol. i. p. 427; for crickets, p. 445.) With +respect to colour, some exotic locusts are beautifully ornamented; the +posterior wings being marked with red, blue, and black; but as throughout +the Order the sexes rarely differ much in colour, it is not probable that +they owe their bright tints to sexual selection. Conspicuous colours may +be of use to these insects, by giving notice that they are unpalatable. +Thus it has been observed (46. Mr. Ch. Horne, in 'Proceedings of the +Entomological Society,' May 3, 1869, p. xii.) that a bright-coloured Indian +locust was invariably rejected when offered to birds and lizards. Some +cases, however, are known of sexual differences in colour in this Order. +The male of an American cricket (47. The Oecanthus nivalis, Harris, +'Insects of New England,' 1842, p. 124. The two sexes of OE. pellucidus of +Europe differ, as I hear from Victor Carus, in nearly the same manner.) is +described as being as white as ivory, whilst the female varies from almost +white to greenish-yellow or dusky. Mr. Walsh informs me that the adult +male of Spectrum femoratum (one of the Phasmidae) "is of a shining +brownish-yellow colour; the adult female being of a dull, opaque, cinereous +brown; the young of both sexes being green." Lastly, I may mention that +the male of one curious kind of cricket (48. Platyblemnus: Westwood, +'Modern Classification,' vol. i. p. 447.) is furnished with "a long +membranous appendage, which falls over the face like a veil;" but what its +use may be, is not known. + +ORDER, NEUROPTERA. + +Little need here be said, except as to colour. In the Ephemeridae the +sexes often differ slightly in their obscure tints (49. B.D. Walsh, the +'Pseudo-neuroptera of Illinois,' in 'Proceedings of the Entomological +Society of Philadelphia,' 1862, p. 361.); but it is not probable that the +males are thus rendered attractive to the females. The Libellulidae, or +dragon-flies, are ornamented with splendid green, blue, yellow, and +vermilion metallic tints; and the sexes often differ. Thus, as Prof. +Westwood remarks (50. 'Modern Classification,' vol. ii. p. 37.), the males +of some of the Agrionidae, "are of a rich blue with black wings, whilst the +females are fine green with colourless wings." But in Agrion Ramburii +these colours are exactly reversed in the two sexes. (51. Walsh, ibid. p. +381. I am indebted to this naturalist for the following facts on +Hetaerina, Anax, and Gomphus.) In the extensive N. American genus of +Hetaerina, the males alone have a beautiful carmine spot at the base of +each wing. In Anax junius the basal part of the abdomen in the male is a +vivid ultramarine blue, and in the female grass-green. In the allied genus +Gomphus, on the other hand, and in some other genera, the sexes differ but +little in colour. In closely-allied forms throughout the animal kingdom, +similar cases of the sexes differing greatly, or very little, or not at +all, are of frequent occurrence. Although there is so wide a difference in +colour between the sexes of many Libellulidae, it is often difficult to say +which is the more brilliant; and the ordinary coloration of the two sexes +is reversed, as we have just seen, in one species of Agrion. It is not +probable that their colours in any case have been gained as a protection. +Mr. MacLachlan, who has closely attended to this family, writes to me that +dragon-flies--the tyrants of the insect-world--are the least liable of any +insect to be attacked by birds or other enemies, and he believes that their +bright colours serve as a sexual attraction. Certain dragon-flies +apparently are attracted by particular colours: Mr. Patterson observed +(52. 'Transactions, Ent. Soc.' vol. i. 1836, p. lxxxi.) that the +Agrionidae, of which the males are blue, settled in numbers on the blue +float of a fishing line; whilst two other species were attracted by shining +white colours. + +It is an interesting fact, first noticed by Schelver, that, in several +genera belonging to two sub-families, the males on first emergence from the +pupal state, are coloured exactly like the females; but that their bodies +in a short time assume a conspicuous milky-blue tint, owing to the +exudation of a kind of oil, soluble in ether and alcohol. Mr. MacLachlan +believes that in the male of Libellula depressa this change of colour does +not occur until nearly a fortnight after the metamorphosis, when the sexes +are ready to pair. + +Certain species of Neurothemis present, according to Brauer (53. See +abstract in the 'Zoological Record' for 1867, p. 450.), a curious case of +dimorphism, some of the females having ordinary wings, whilst others have +them "very richly netted, as in the males of the same species." Brauer +"explains the phenomenon on Darwinian principles by the supposition that +the close netting of the veins is a secondary sexual character in the +males, which has been abruptly transferred to some of the females, instead +of, as generally occurs, to all of them." Mr. MacLachlan informs me of +another instance of dimorphism in several species of Agrion, in which some +individuals are of an orange colour, and these are invariably females. +This is probably a case of reversion; for in the true Libellulae, when the +sexes differ in colour, the females are orange or yellow; so that supposing +Agrion to be descended from some primordial form which resembled the +typical Libellulae in its sexual characters, it would not be surprising +that a tendency to vary in this manner should occur in the females alone. + +Although many dragon-flies are large, powerful, and fierce insects, the +males have not been observed by Mr. MacLachlan to fight together, +excepting, as he believes, in some of the smaller species of Agrion. In +another group in this Order, namely, the Termites or white ants, both sexes +at the time of swarming may be seen running about, "the male after the +female, sometimes two chasing one female, and contending with great +eagerness who shall win the prize." (54. Kirby and Spence, 'Introduction +to Entomology,' vol. ii. 1818, p. 35.) The Atropos pulsatorius is said to +make a noise with its jaws, which is answered by other individuals. (55. +Houzeau, 'Les Facultés Mentales,' etc. Tom. i. p. 104.) + +ORDER, HYMENOPTERA. + +That inimitable observer, M. Fabre (56. See an interesting article, 'The +Writings of Fabre,' in 'Nat. Hist. Review,' April 1862, p. 122.), in +describing the habits of Cerceris, a wasp-like insect, remarks that "fights +frequently ensue between the males for the possession of some particular +female, who sits an apparently unconcerned beholder of the struggle for +supremacy, and when the victory is decided, quietly flies away in company +with the conqueror." Westwood (57. 'Journal of Proceedings of +Entomological Society,' Sept. 7, 1863, p. 169.) says that the males of one +of the saw-flies (Tenthredinae) "have been found fighting together, with +their mandibles locked." As M. Fabre speaks of the males of Cerceris +striving to obtain a particular female, it may be well to bear in mind that +insects belonging to this Order have the power of recognising each other +after long intervals of time, and are deeply attached. For instance, +Pierre Huber, whose accuracy no one doubts, separated some ants, and when, +after an interval of four months, they met others which had formerly +belonged to the same community, they recognised and caressed one another +with their antennae. Had they been strangers they would have fought +together. Again, when two communities engage in a battle, the ants on the +same side sometimes attack each other in the general confusion, but they +soon perceive their mistake, and the one ant soothes the other. (58. P. +Huber, 'Recherches sur les Moeurs des Fourmis,' 1810, pp. 150, 165.) + +In this Order slight differences in colour, according to sex, are common, +but conspicuous differences are rare except in the family of Bees; yet both +sexes of certain groups are so brilliantly coloured--for instance in +Chrysis, in which vermilion and metallic greens prevail--that we are +tempted to attribute the result to sexual selection. In the Ichneumonidae, +according to Mr. Walsh (59. 'Proceedings of the Entomological Society of +Philadelphia,' 1866, pp. 238, 239.), the males are almost universally +lighter-coloured than the females. On the other hand, in the +Tenthredinidae the males are generally darker than the females. In the +Siricidae the sexes frequently differ; thus the male of Sirex juvencus is +banded with orange, whilst the female is dark purple; but it is difficult +to say which sex is the more ornamented. In Tremex columbae the female is +much brighter coloured than the male. I am informed by Mr. F. Smith, that +the male ants of several species are black, the females being testaceous. + +In the family of Bees, especially in the solitary species, as I hear from +the same entomologist, the sexes often differ in colour. The males are +generally the brighter, and in Bombus as well as in Apathus, much more +variable in colour than the females. In Anthophora retusa the male is of a +rich fulvous-brown, whilst the female is quite black: so are the females +of several species of Xylocopa, the males being bright yellow. On the +other hand the females of some species, as of Andraena fulva, are much +brighter coloured than the males. Such differences in colour can hardly be +accounted for by the males being defenceless and thus requiring protection, +whilst the females are well defended by their stings. H. Müller (60. +'Anwendung der Darwinschen Lehre auf Bienen,' Verh. d. n. V. Jahrg. xxix.), +who has particularly attended to the habits of bees, attributes these +differences in colour in chief part to sexual selection. That bees have a +keen perception of colour is certain. He says that the males search +eagerly and fight for the possession of the females; and he accounts +through such contests for the mandibles of the males being in certain +species larger than those of the females. In some cases the males are far +more numerous than the females, either early in the season, or at all times +and places, or locally; whereas the females in other cases are apparently +in excess. In some species the more beautiful males appear to have been +selected by the females; and in others the more beautiful females by the +males. Consequently in certain genera (Müller, p. 42), the males of the +several species differ much in appearance, whilst the females are almost +indistinguishable; in other genera the reverse occurs. H. Müller believes +(p. 82) that the colours gained by one sex through sexual selection have +often been transferred in a variable degree to the other sex, just as the +pollen-collecting apparatus of the female has often been transferred to the +male, to whom it is absolutely useless. (61. M. Perrier in his article +'la Selection sexuelle d'après Darwin' ('Revue Scientifique,' Feb. 1873, p. +868), without apparently having reflected much on the subject, objects that +as the males of social bees are known to be produced from unfertilised ova, +they could not transmit new characters to their male offspring. This is an +extraordinary objection. A female bee fertilised by a male, which +presented some character facilitating the union of the sexes, or rendering +him more attractive to the female, would lay eggs which would produce only +females; but these young females would next year produce males; and will it +be pretended that such males would not inherit the characters of their male +grandfathers? To take a case with ordinary animals as nearly parallel as +possible: if a female of any white quadruped or bird were crossed by a +male of a black breed, and the male and female offspring were paired +together, will it be pretended that the grandchildren would not inherit a +tendency to blackness from their male grandfather? The acquirement of new +characters by the sterile worker-bees is a much more difficult case, but I +have endeavoured to shew in my 'Origin of Species,' how these sterile +beings are subjected to the power of natural selection.) + +Mutilla Europaea makes a stridulating noise; and according to Goureau (62. +Quoted by Westwood, 'Modern Classification of Insects,' vol. ii. p. 214.) +both sexes have this power. He attributes the sound to the friction of the +third and preceding abdominal segments, and I find that these surfaces are +marked with very fine concentric ridges; but so is the projecting thoracic +collar into which the head articulates, and this collar, when scratched +with the point of a needle, emits the proper sound. It is rather +surprising that both sexes should have the power of stridulating, as the +male is winged and the female wingless. It is notorious that Bees express +certain emotions, as of anger, by the tone of their humming; and according +to H. Müller (p. 80), the males of some species make a peculiar singing +noise whilst pursuing the females. + +ORDER, COLEOPTERA (BEETLES). + +Many beetles are coloured so as to resemble the surfaces which they +habitually frequent, and they thus escape detection by their enemies. +Other species, for instance diamond-beetles, are ornamented with splendid +colours, which are often arranged in stripes, spots, crosses, and other +elegant patterns. Such colours can hardly serve directly as a protection, +except in the case of certain flower-feeding species; but they may serve as +a warning or means of recognition, on the same principle as the +phosphorescence of the glow-worm. As with beetles the colours of the two +sexes are generally alike, we have no evidence that they have been gained +through sexual selection; but this is at least possible, for they have been +developed in one sex and then transferred to the other; and this view is +even in some degree probable in those groups which possess other well- +marked secondary sexual characters. Blind beetles, which cannot of course +behold each other's beauty, never, as I hear from Mr. Waterhouse, jun., +exhibit bright colours, though they often have polished coats; but the +explanation of their obscurity may be that they generally inhabit caves and +other obscure stations. + +Some Longicorns, especially certain Prionidae, offer an exception to the +rule that the sexes of beetles do not differ in colour. Most of these +insects are large and splendidly coloured. The males in the genus Pyrodes +(63. Pyrodes pulcherrimus, in which the sexes differ conspicuously, has +been described by Mr. Bates in 'Transact. Ent. Soc.' 1869, p. 50. I will +specify the few other cases in which I have heard of a difference in colour +between the sexes of beetles. Kirby and Spence ('Introduct. to +Entomology,' vol. iii. p. 301) mention a Cantharis, Meloe, Rhagium, and the +Leptura testacea; the male of the latter being testaceous, with a black +thorax, and the female of a dull red all over. These two latter beetles +belong to the family of Longicorns. Messrs. R. Trimen and Waterhouse, +jun., inform me of two Lamellicorns, viz., a Peritrichia and Trichius, the +male of the latter being more obscurely coloured than the female. In +Tillus elongatus the male is black, and the female always, as it is +believed, of a dark blue colour, with a red thorax. The male, also, of +Orsodacna atra, as I hear from Mr. Walsh, is black, the female (the so- +called O. ruficollis) having a rufous thorax.), which I saw in Mr. Bates's +collection, are generally redder but rather duller than the females, the +latter being coloured of a more or less splendid golden-green. On the +other hand, in one species the male is golden-green, the female being +richly tinted with red and purple. In the genus Esmeralda the sexes differ +so greatly in colour that they have been ranked as distinct species; in one +species both are of a beautiful shining green, but the male has a red +thorax. On the whole, as far as I could judge, the females of those +Prionidae, in which the sexes differ, are coloured more richly than the +males, and this does not accord with the common rule in regard to colour, +when acquired through sexual selection. + +[Fig.16. Chalcosoma atlas. +Upper figure, male (reduced); +lower figure, female (nat. size). + +Fig. 17. Copris isidis. + +Fig. 18. Phanaeus faunus. + +Fig. 19. Dipelicus cantori. + +Fig. 20. Onthophagus rangifer, enlarged. +(In Figs. 17 to 20 the left-hand figures are males.)] + +A most remarkable distinction between the sexes of many beetles is +presented by the great horns which rise from the head, thorax, and clypeus +of the males; and in some few cases from the under surface of the body. +These horns, in the great family of the Lamellicorns, resemble those of +various quadrupeds, such as stags, rhinoceroses, etc., and are wonderful +both from their size and diversified shapes. Instead of describing them, I +have given figures of the males and females of some of the more remarkable +forms. (Figs. 16 to 20.) The females generally exhibit rudiments of the +horns in the form of small knobs or ridges; but some are destitute of even +the slightest rudiment. On the other hand, the horns are nearly as well +developed in the female as in the male Phanaeus lancifer; and only a little +less well developed in the females of some other species of this genus and +of Copris. I am informed by Mr. Bates that the horns do not differ in any +manner corresponding with the more important characteristic differences +between the several subdivisions of the family: thus within the same +section of the genus Onthophagus, there are species which have a single +horn, and others which have two. + +In almost all cases, the horns are remarkable from their excessive +variability; so that a graduated series can be formed, from the most highly +developed males to others so degenerate that they can barely be +distinguished from the females. Mr. Walsh (64. 'Proceedings of the +Entomological Society of Philadephia,' 1864, p. 228.) found that in +Phanaeus carnifex the horns were thrice as long in some males as in others. +Mr. Bates, after examining above a hundred males of Onthophagus rangifer +(Fig. 20), thought that he had at last discovered a species in which the +horns did not vary; but further research proved the contrary. + +The extraordinary size of the horns, and their widely different structure +in closely-allied forms, indicate that they have been formed for some +purpose; but their excessive variability in the males of the same species +leads to the inference that this purpose cannot be of a definite nature. +The horns do not shew marks of friction, as if used for any ordinary work. +Some authors suppose (65. Kirby and Spence, 'Introduction to Entomology,' +vol. iii. P. 300.) that as the males wander about much more than the +females, they require horns as a defence against their enemies; but as the +horns are often blunt, they do not seem well adapted for defence. The most +obvious conjecture is that they are used by the males for fighting +together; but the males have never been observed to fight; nor could Mr. +Bates, after a careful examination of numerous species, find any sufficient +evidence, in their mutilated or broken condition, of their having been thus +used. If the males had been habitual fighters, the size of their bodies +would probably have been increased through sexual selection, so as to have +exceeded that of the females; but Mr. Bates, after comparing the two sexes +in above a hundred species of the Copridae, did not find any marked +difference in this respect amongst well-developed individuals. In Lethrus, +moreover, a beetle belonging to the same great division of the +Lamellicorns, the males are known to fight, but are not provided with +horns, though their mandibles are much larger than those of the female. + +The conclusion that the horns have been acquired as ornaments is that which +best agrees with the fact of their having been so immensely, yet not +fixedly, developed,--as shewn by their extreme variability in the same +species, and by their extreme diversity in closely-allied species. This +view will at first appear extremely improbable; but we shall hereafter find +with many animals standing much higher in the scale, namely fishes, +amphibians, reptiles and birds, that various kinds of crests, knobs, horns +and combs have been developed apparently for this sole purpose. + +[Fig.21. Onitis furcifer, male viewed from beneath. + +Fig.22. Onitis furcifer. +Left-hand figure, male, viewed laterally. +Right-hand figure, female. +a. Rudiment of cephalic horn. +b. Trace of thoracic horn or crest.] + +The males of Onitis furcifer (Fig. 21), and of some other species of the +genus, are furnished with singular projections on their anterior femora, +and with a great fork or pair of horns on the lower surface of the thorax. +Judging from other insects, these may aid the male in clinging to the +female. Although the males have not even a trace of a horn on the upper +surface of the body, yet the females plainly exhibit a rudiment of a single +horn on the head (Fig. 22, a), and of a crest (b) on the thorax. That the +slight thoracic crest in the female is a rudiment of a projection proper to +the male, though entirely absent in the male of this particular species, is +clear: for the female of Bubas bison (a genus which comes next to Onitis) +has a similar slight crest on the thorax, and the male bears a great +projection in the same situation. So, again, there can hardly be a doubt +that the little point (a) on the head of the female Onitis furcifer, as +well as on the head of the females of two or three allied species, is a +rudimentary representative of the cephalic horn, which is common to the +males of so many Lamellicorn beetles, as in Phanaeus (Fig. 18). + +The old belief that rudiments have been created to complete the scheme of +nature is here so far from holding good, that we have a complete inversion +of the ordinary state of things in the family. We may reasonably suspect +that the males originally bore horns and transferred them to the females in +a rudimentary condition, as in so many other Lamellicorns. Why the males +subsequently lost their horns, we know not; but this may have been caused +through the principle of compensation, owing to the development of the +large horns and projections on the lower surface; and as these are confined +to the males, the rudiments of the upper horns on the females would not +have been thus obliterated. + +[Fig. 23. Bledius taurus, magnified. +Left-hand figure, male; +right-hand figure, female.] + +The cases hitherto given refer to the Lamellicorns, but the males of some +few other beetles, belonging to two widely distinct groups, namely, the +Curculionidae and Staphylinidae, are furnished with horns--in the former on +the lower surface of the body (66. Kirby and Spence, 'Introduction to +Entomology,' vol. iii. p. 329.), in the latter on the upper surface of the +head and thorax. In the Staphylinidae, the horns of the males are +extraordinarily variable in the same species, just as we have seen with the +Lamellicorns. In Siagonium we have a case of dimorphism, for the males can +be divided into two sets, differing greatly in the size of their bodies and +in the development of their horns, without intermediate gradations. In a +species of Bledius (Fig. 23), also belonging to the Staphylinidae, +Professor Westwood states that, "male specimens can be found in the same +locality in which the central horn of the thorax is very large, but the +horns of the head quite rudimental; and others, in which the thoracic horn +is much shorter, whilst the protuberances on the head are long." (67. +'Modern Classification of Insects,' vol. i. p. 172: Siagonium, p. 172. In +the British Museum I noticed one male specimen of Siagonium in an +intermediate condition, so that the dimorphism is not strict.) Here we +apparently have a case of compensation, which throws light on that just +given, of the supposed loss of the upper horns by the males of Onitis. + +LAW OF BATTLE. + +Some male beetles, which seem ill-fitted for fighting, nevertheless engage +in conflicts for the possession of the females. Mr. Wallace (68. 'The +Malay Archipelago,' vol. ii. 1869, p. 276. Riley, Sixth 'Report on Insects +of Missouri,' 1874, p. 115.) saw two males of Leptorhynchus angustatus, a +linear beetle with a much elongated rostrum, "fighting for a female, who +stood close by busy at her boring. They pushed at each other with their +rostra, and clawed and thumped, apparently in the greatest rage." The +smaller male, however, "soon ran away, acknowledging himself vanquished." +In some few cases male beetles are well adapted for fighting, by possessing +great toothed mandibles, much larger than those of the females. This is +the case with the common stag-beetle (Lucanus cervus), the males of which +emerge from the pupal state about a week before the other sex, so that +several may often be seen pursuing the same female. At this season they +engage in fierce conflicts. When Mr. A.H. Davis (69. 'Entomological +Magazine,' vol. i. 1833, p. 82. See also on the conflicts of this species, +Kirby and Spence, ibid. vol. iii. p. 314; and Westwood, ibid. vol. i. p. +187.) enclosed two males with one female in a box, the larger male severely +pinched the smaller one, until he resigned his pretensions. A friend +informs me that when a boy he often put the males together to see them +fight, and he noticed that they were much bolder and fiercer than the +females, as with the higher animals. The males would seize hold of his +finger, if held in front of them, but not so the females, although they +have stronger jaws. The males of many of the Lucanidae, as well as of the +above-mentioned Leptorhynchus, are larger and more powerful insects than +the females. The two sexes of Lethrus cephalotes (one of the Lamellicorns) +inhabit the same burrow; and the male has larger mandibles than the female. +If, during the breeding-season, a strange male attempts to enter the +burrow, he is attacked; the female does not remain passive, but closes the +mouth of the burrow, and encourages her mate by continually pushing him on +from behind; and the battle lasts until the aggressor is killed or runs +away. (70. Quoted from Fischer, in 'Dict. Class. d'Hist. Nat.' tom. x. p. +324.) The two sexes of another Lamellicorn beetle, the Ateuchus +cicatricosus, live in pairs, and seem much attached to each other; the male +excites the females to roll the balls of dung in which the ova are +deposited; and if she is removed, he becomes much agitated. If the male is +removed the female ceases all work, and as M. Brulerie believes, would +remain on the same spot until she died. (71. 'Ann. Soc. Entomolog. +France,' 1866, as quoted in 'Journal of Travel,' by A. Murray, 1868, p. +135.) + +[Fig. 24. Chiasognathus Grantii, reduced. +Upper figure, male; +lower figure, female.] + +The great mandibles of the male Lucanidae are extremely variable both in +size and structure, and in this respect resemble the horns on the head and +thorax of many male Lamellicorns and Staphylinidae. A perfect series can +be formed from the best-provided to the worst-provided or degenerate males. +Although the mandibles of the common stag-beetle, and probably of many +other species, are used as efficient weapons for fighting, it is doubtful +whether their great size can thus be accounted for. We have seen that they +are used by the Lucanus elaphus of N. America for seizing the female. As +they are so conspicuous and so elegantly branched, and as owing to their +great length they are not well adapted for pinching, the suspicion has +crossed my mind that they may in addition serve as an ornament, like the +horns on the head and thorax of the various species above described. The +male Chiasognathus grantii of S. Chile--a splendid beetle belonging to the +same family--has enormously developed mandibles (Fig. 24); he is bold and +pugnacious; when threatened he faces round, opens his great jaws, and at +the same time stridulates loudly. But the mandibles were not strong enough +to pinch my finger so as to cause actual pain. + +Sexual selection, which implies the possession of considerable perceptive +powers and of strong passions, seems to have been more effective with the +Lamellicorns than with any other family of beetles. With some species the +males are provided with weapons for fighting; some live in pairs and shew +mutual affection; many have the power of stridulating when excited; many +are furnished with the most extraordinary horns, apparently for the sake of +ornament; and some, which are diurnal in their habits, are gorgeously +coloured. Lastly, several of the largest beetles in the world belong to +this family, which was placed by Linnaeus and Fabricius as the head of the +Order. (72. Westwood, 'Modern Classification,' vol. i. p. 184.) + +STRIDULATING ORGANS. + +Beetles belonging to many and widely distinct families possess these +organs. The sound thus produced can sometimes be heard at the distance of +several feet or even yards (73. Wollaston, 'On Certain Musical +Curculionidae,' 'Annals and Mag. of Nat. Hist.' vol. vi. 1860, p. 14.), but +it is not comparable with that made by the Orthoptera. The rasp generally +consists of a narrow, slightly-raised surface, crossed by very fine, +parallel ribs, sometimes so fine as to cause iridescent colours, and having +a very elegant appearance under the microscope. In some cases, as with +Typhoeus, minute, bristly or scale-like prominences, with which the whole +surrounding surface is covered in approximately parallel lines, could be +traced passing into the ribs of the rasp. The transition takes place by +their becoming confluent and straight, and at the same time more prominent +and smooth. A hard ridge on an adjoining part of the body serves as the +scraper for the rasp, but this scraper in some cases has been specially +modified for the purpose. It is rapidly moved across the rasp, or +conversely the rasp across the scraper. + +[Fig.25. Necrophorus (from Landois). +r. The two rasps. +Left-hand figure, part of the rasp highly magnified.] + +These organs are situated in widely different positions. In the carrion- +beetles (Necrophorus) two parallel rasps (r, Fig. 25) stand on the dorsal +surface of the fifth abdominal segment, each rasp (74. Landois, +'Zeitschrift fur wissenschaft Zoolog.' B. xvii. 1867, s. 127.) consisting +of 126 to 140 fine ribs. These ribs are scraped against the posterior +margins of the elytra, a small portion of which projects beyond the general +outline. In many Crioceridae, and in Clythra 4-punctata (one of the +Chrysomelidae), and in some Tenebrionidae, etc. (75. I am greatly indebted +to Mr. G.R. Crotch for having sent me many prepared specimens of various +beetles belonging to these three families and to others, as well as for +valuable information. He believes that the power of stridulation in the +Clythra has not been previously observed. I am also much indebted to Mr. +E.W. Janson, for information and specimens. I may add that my son, Mr. F. +Darwin, finds that Dermestes murinus stridulates, but he searched in vain +for the apparatus. Scolytus has lately been described by Dr. Chapman as a +stridulator, in the 'Entomologist's Monthly Magazine,' vol. vi. p. 130.), +the rasp is seated on the dorsal apex of the abdomen, on the pygidium or +pro-pygidium, and is scraped in the same manner by the elytra. In +Heterocerus, which belongs to another family, the rasps are placed on the +sides of the first abdominal segment, and are scraped by ridges on the +femora. (76. Schiodte, translated, in 'Annals and Magazine of Natural +History,' vol. xx. 1867, p. 37.) In certain Curculionidae and Carabidae +(77. Westring has described (Kroyer, 'Naturhist. Tidskrift,' B. ii. 1848- +49, p. 334) the stridulating organs in these two, as well as in other +families. In the Carabidae I have examined Elaphrus uliginosus and +Blethisa multipunctata, sent to me by Mr. Crotch. In Blethisa the +transverse ridges on the furrowed border of the abdominal segment do not, +as far as I could judge, come into play in scraping the rasps on the +elytra.), the parts are completely reversed in position, for the rasps are +seated on the inferior surface of the elytra, near their apices, or along +their outer margins, and the edges of the abdominal segments serve as the +scrapers. In Pelobius Hermanni (one of Dytiscidae or water-beetles) a +strong ridge runs parallel and near to the sutural margin of the elytra, +and is crossed by ribs, coarse in the middle part, but becoming gradually +finer at both ends, especially at the upper end; when this insect is held +under water or in the air, a stridulating noise is produced by the extreme +horny margin of the abdomen being scraped against the rasps. In a great +number of long-horned beetles (Longicornia) the organs are situated quite +otherwise, the rasp being on the meso-thorax, which is rubbed against the +pro-thorax; Landois counted 238 very fine ribs on the rasp of Cerambyx +heros. + +[Fig.26. Hind-leg of Geotrupes stercorarius (from Landois). +r. Rasp. c. Coxa. f. Femur. t. Tibia. tr. Tarsi.] + +Many Lamellicorns have the power of stridulating, and the organs differ +greatly in position. Some species stridulate very loudly, so that when Mr. +F. Smith caught a Trox sabulosus, a gamekeeper, who stood by, thought he +had caught a mouse; but I failed to discover the proper organs in this +beetle. In Geotrupes and Typhoeus, a narrow ridge runs obliquely across +(r, Fig. 26) the coxa of each hind-leg (having in G. stercorarius 84 ribs), +which is scraped by a specially projecting part of one of the abdominal +segments. In the nearly allied Copris lunaris, an excessively narrow fine +rasp runs along the sutural margin of the elytra, with another short rasp +near the basal outer margin; but in some other Coprini the rasp is seated, +according to Leconte (78. I am indebted to Mr. Walsh, of Illinois, for +having sent me extracts from Leconte's 'Introduction to Entomology,' pp. +101, 143.), on the dorsal surface of the abdomen. In Oryctes it is seated +on the pro-pygidium; and, according to the same entomologist, in some other +Dynastini, on the under surface of the elytra. Lastly, Westring states +that in Omaloplia brunnea the rasp is placed on the pro-sternum, and the +scraper on the meta-sternum, the parts thus occupying the under surface of +the body, instead of the upper surface as in the Longicorns. + +We thus see that in the different coleopterous families the stridulating +organs are wonderfully diversified in position, but not much in structure. +Within the same family some species are provided with these organs, and +others are destitute of them. This diversity is intelligible, if we +suppose that originally various beetles made a shuffling or hissing noise +by the rubbing together of any hard and rough parts of their bodies, which +happened to be in contact; and that from the noise thus produced being in +some way useful, the rough surfaces were gradually developed into regular +stridulating organs. Some beetles as they move, now produce, either +intentionally or unintentionally, a shuffling noise, without possessing any +proper organs for the purpose. Mr. Wallace informs me that the Euchirus +longimanus (a Lamellicorn, with the anterior legs wonderfully elongated in +the male) "makes, whilst moving, a low hissing sound by the protrusion and +contraction of the abdomen; and when seized it produces a grating sound by +rubbing its hind-legs against the edges of the elytra." The hissing sound +is clearly due to a narrow rasp running along the sutural margin of each +elytron; and I could likewise make the grating sound by rubbing the +shagreened surface of the femur against the granulated margin of the +corresponding elytron; but I could not here detect any proper rasp; nor is +it likely that I could have overlooked it in so large an insect. After +examining Cychrus, and reading what Westring has written about this beetle, +it seems very doubtful whether it possesses any true rasp, though it has +the power of emitting a sound. + +From the analogy of the Orthoptera and Homoptera, I expected to find the +stridulating organs in the Coleoptera differing according to sex; but +Landois, who has carefully examined several species, observed no such +difference; nor did Westring; nor did Mr. G.R. Crotch in preparing the many +specimens which he had the kindness to send me. Any difference in these +organs, if slight, would, however, be difficult to detect, on account of +their great variability. Thus, in the first pair of specimens of +Necrophorus humator and of Pelobius which I examined, the rasp was +considerably larger in the male than in the female; but not so with +succeeding specimens. In Geotrupes stercorarius the rasp appeared to me +thicker, opaquer, and more prominent in three males than in the same number +of females; in order, therefore, to discover whether the sexes differed in +their power of stridulating, my son, Mr. F. Darwin, collected fifty-seven +living specimens, which he separated into two lots, according as they made +a greater or lesser noise, when held in the same manner. He then examined +all these specimens, and found that the males were very nearly in the same +proportion to the females in both the lots. Mr. F. Smith has kept alive +numerous specimens of Monoynchus pseudacori (Curculionidae), and is +convinced that both sexes stridulate, and apparently in an equal degree. + +Nevertheless, the power of stridulating is certainly a sexual character in +some few Coleoptera. Mr. Crotch discovered that the males alone of two +species of Heliopathes (Tenebrionidae) possess stridulating organs. I +examined five males of H. gibbus, and in all these there was a well- +developed rasp, partially divided into two, on the dorsal surface of the +terminal abdominal segment; whilst in the same number of females there was +not even a rudiment of the rasp, the membrane of this segment being +transparent, and much thinner than in the male. In H. cribratostriatus the +male has a similar rasp, excepting that it is not partially divided into +two portions, and the female is completely destitute of this organ; the +male in addition has on the apical margins of the elytra, on each side of +the suture, three or four short longitudinal ridges, which are crossed by +extremely fine ribs, parallel to and resembling those on the abdominal +rasp; whether these ridges serve as an independent rasp, or as a scraper +for the abdominal rasp, I could not decide: the female exhibits no trace +of this latter structure. + +Again, in three species of the Lamellicorn genus Oryctes, we have a nearly +parallel case. In the females of O. gryphus and nasicornis the ribs on the +rasp of the pro-pygidium are less continuous and less distinct than in the +males; but the chief difference is that the whole upper surface of this +segment, when held in the proper light, is seen to be clothed with hairs, +which are absent or are represented by excessively fine down in the males. +It should be noticed that in all Coleoptera the effective part of the rasp +is destitute of hairs. In O. senegalensis the difference between the sexes +is more strongly marked, and this is best seen when the proper abdominal +segment is cleaned and viewed as a transparent object. In the female the +whole surface is covered with little separate crests, bearing spines; +whilst in the male these crests in proceeding towards the apex, become more +and more confluent, regular, and naked; so that three-fourths of the +segment is covered with extremely fine parallel ribs, which are quite +absent in the female. In the females, however, of all three species of +Oryctes, a slight grating or stridulating sound is produced, when the +abdomen of a softened specimen is pushed backwards and forwards. + +In the case of the Heliopathes and Oryctes there can hardly be a doubt that +the males stridulate in order to call or to excite the females; but with +most beetles the stridulation apparently serves both sexes as a mutual +call. Beetles stridulate under various emotions, in the same manner as +birds use their voices for many purposes besides singing to their mates. +The great Chiasognathus stridulates in anger or defiance; many species do +the same from distress or fear, if held so that they cannot escape; by +striking the hollow stems of trees in the Canary Islands, Messrs. Wollaston +and Crotch were able to discover the presence of beetles belonging to the +genus Acalles by their stridulation. Lastly, the male Ateuchus stridulates +to encourage the female in her work, and from distress when she is removed. +(79. M. P. de la Brulerie, as quoted in 'Journal of Travel,' A. Murray, +vol. i. 1868, p. 135.) Some naturalists believe that beetles make this +noise to frighten away their enemies; but I cannot think that a quadruped +or bird, able to devour a large beetle, would be frightened by so slight a +sound. The belief that the stridulation serves as a sexual call is +supported by the fact that death-ticks (Anobium tessellatum) are well known +to answer each other's ticking, and, as I have myself observed, a tapping +noise artificially made. Mr. Doubleday also informs me that he has +sometimes observed a female ticking (80. According to Mr. Doubleday, "the +noise is produced by the insect raising itself on its legs as high as it +can, and then striking its thorax five or six times, in rapid succession, +against the substance upon which it is sitting." For references on this +subject see Landois, 'Zeitschrift für wissen. Zoolog.' B. xvii. s. 131. +Olivier says (as quoted by Kirby and Spence, 'Introduction to Entomology,' +vol. ii. p. 395) that the female of Pimelia striata produces a rather loud +sound by striking her abdomen against any hard substance, "and that the +male, obedient to this call, soon attends her, and they pair."), and in an +hour or two afterwards has found her united with a male, and on one +occasion surrounded by several males. Finally, it is probable that the two +sexes of many kinds of beetles were at first enabled to find each other by +the slight shuffling noise produced by the rubbing together of the +adjoining hard parts of their bodies; and that as those males or females +which made the greatest noise succeeded best in finding partners, +rugosities on various parts of their bodies were gradually developed by +means of sexual selection into true stridulating organs. + + +CHAPTER XI. + +INSECTS, continued. + +ORDER LEPIDOPTERA. (BUTTERFLIES AND MOTHS.) + +Courtship of butterflies--Battles--Ticking noise--Colours common to both +sexes, or more brilliant in the males--Examples--Not due to the direct +action of the conditions of life--Colours adapted for protection--Colours +of moths--Display--Perceptive powers of the Lepidoptera--Variability-- +Causes of the difference in colour between the males and females--Mimicry, +female butterflies more brilliantly coloured than the males--Bright colours +of caterpillars--Summary and concluding remarks on the secondary sexual +characters of insects--Birds and insects compared. + +In this great Order the most interesting points for us are the differences +in colour between the sexes of the same species, and between the distinct +species of the same genus. Nearly the whole of the following chapter will +be devoted to this subject; but I will first make a few remarks on one or +two other points. Several males may often be seen pursuing and crowding +round the same female. Their courtship appears to be a prolonged affair, +for I have frequently watched one or more males pirouetting round a female +until I was tired, without seeing the end of the courtship. Mr. A.G. +Butler also informs me that he has several times watched a male courting a +female for a full quarter of an hour; but she pertinaciously refused him, +and at last settled on the ground and closed her wings, so as to escape +from his addresses. + +Although butterflies are weak and fragile creatures, they are pugnacious, +and an emperor butterfly (1. Apatura Iris: 'The Entomologist's Weekly +Intelligence,' 1859, p. 139. For the Bornean Butterflies, see C. +Collingwood, 'Rambles of a Naturalist,' 1868, p. 183.) has been captured +with the tips of its wings broken from a conflict with another male. Mr. +Collingwood, in speaking of the frequent battles between the butterflies of +Borneo, says, "They whirl round each other with the greatest rapidity, and +appear to be incited by the greatest ferocity." + +The Ageronia feronia makes a noise like that produced by a toothed wheel +passing under a spring catch, and which can be heard at the distance of +several yards: I noticed this sound at Rio de Janeiro, only when two of +these butterflies were chasing each other in an irregular course, so that +it is probably made during the courtship of the sexes. (2. See my +'Journal of Researches,' 1845, p. 33. Mr. Doubleday has detected ('Proc. +Ent. Soc.' March 3, 1845, p. 123) a peculiar membranous sac at the base of +the front wings, which is probably connected with the production of the +sound. For the case of Thecophora, see 'Zoological Record,' 1869, p. 401. +For Mr. Buchanan White's observations, the Scottish Naturalist, July 1872, +p. 214.) + +Some moths also produce sounds; for instance, the males Theocophora fovea. +On two occasions Mr. F. Buchanan White (3. 'The Scottish Naturalist,' July +1872, p. 213.) heard a sharp quick noise made by the male of Hylophila +prasinana, and which he believes to be produced, as in Cicada, by an +elastic membrane, furnished with a muscle. He quotes, also, Guenee, that +Setina produces a sound like the ticking of a watch, apparently by the aid +of "two large tympaniform vesicles, situated in the pectoral region"; and +these "are much more developed in the male than in the female." Hence the +sound-producing organs in the Lepidoptera appear to stand in some relation +with the sexual functions. I have not alluded to the well-known noise made +by the Death's Head Sphinx, for it is generally heard soon after the moth +has emerged from its cocoon. + +Giard has always observed that the musky odour, which is emitted by two +species of Sphinx moths, is peculiar to the males (4. 'Zoological Record,' +1869, p. 347.); and in the higher classes we shall meet with many instances +of the males alone being odoriferous. + +Every one must have admired the extreme beauty of many butterflies and of +some moths; and it may be asked, are their colours and diversified patterns +the result of the direct action of the physical conditions to which these +insects have been exposed, without any benefit being thus derived? Or have +successive variations been accumulated and determined as a protection, or +for some unknown purpose, or that one sex may be attractive to the other? +And, again, what is the meaning of the colours being widely different in +the males and females of certain species, and alike in the two sexes of +other species of the same genus? Before attempting to answer these +questions a body of facts must be given. + +With our beautiful English butterflies, the admiral, peacock, and painted +lady (Vanessae), as well as many others, the sexes are alike. This is also +the case with the magnificent Heliconidae, and most of the Danaidae in the +tropics. But in certain other tropical groups, and in some of our English +butterflies, as the purple emperor, orange-tip, etc. (Apatura Iris and +Anthocharis cardamines), the sexes differ either greatly or slightly in +colour. No language suffices to describe the splendour of the males of +some tropical species. Even within the same genus we often find species +presenting extraordinary differences between the sexes, whilst others have +their sexes closely alike. Thus in the South American genus Epicalia, Mr. +Bates, to whom I am indebted for most of the following facts, and for +looking over this whole discussion, informs me that he knows twelve +species, the two sexes of which haunt the same stations (and this is not +always the case with butterflies), and which, therefore, cannot have been +differently affected by external conditions. (5. See also Mr. Bates's +paper in 'Proc. Ent. Soc. of Philadelphia,' 1865, p. 206. Also Mr. Wallace +on the same subject, in regard to Diadema, in 'Transactions, Entomological +Society of London,' 1869, p. 278.) In nine of these twelve species the +males rank amongst the most brilliant of all butterflies, and differ so +greatly from the comparatively plain females that they were formerly placed +in distinct genera. The females of these nine species resemble each other +in their general type of coloration; and they likewise resemble both sexes +of the species in several allied genera found in various parts of the +world. Hence we may infer that these nine species, and probably all the +others of the genus, are descended from an ancestral form which was +coloured in nearly the same manner. In the tenth species the female still +retains the same general colouring, but the male resembles her, so that he +is coloured in a much less gaudy and contrasted manner than the males of +the previous species. In the eleventh and twelfth species, the females +depart from the usual type, for they are gaily decorated almost like the +males, but in a somewhat less degree. Hence in these two latter species +the bright colours of the males seem to have been transferred to the +females; whilst in the tenth species the male has either retained or +recovered the plain colours of the female, as well as of the parent-form of +the genus. The sexes in these three cases have thus been rendered nearly +alike, though in an opposite manner. In the allied genus Eubagis, both +sexes of some of the species are plain-coloured and nearly alike; whilst +with the greater number the males are decorated with beautiful metallic +tints in a diversified manner, and differ much from their females. The +females throughout the genus retain the same general style of colouring, so +that they resemble one another much more closely than they resemble their +own males. + +In the genus Papilio, all the species of the Aeneas group are remarkable +for their conspicuous and strongly contrasted colours, and they illustrate +the frequent tendency to gradation in the amount of difference between the +sexes. In a few species, for instance in P. ascanius, the males and +females are alike; in others the males are either a little brighter, or +very much more superb than the females. The genus Junonia, allied to our +Vanessae, offers a nearly parallel case, for although the sexes of most of +the species resemble each other, and are destitute of rich colours, yet in +certain species, as in J. oenone, the male is rather more bright-coloured +than the female, and in a few (for instance J. andremiaja) the male is so +different from the female that he might be mistaken for an entirely +distinct species. + +Another striking case was pointed out to me in the British Museum by Mr. A. +Butler, namely, one of the tropical American Theclae, in which both sexes +are nearly alike and wonderfully splendid; in another species the male is +coloured in a similarly gorgeous manner, whilst the whole upper surface of +the female is of a dull uniform brown. Our common little English blue +butterflies of the genus Lycaena, illustrate the various differences in +colour between the sexes, almost as well, though not in so striking a +manner, as the above exotic genera. In Lycaena agestis both sexes have +wings of a brown colour, bordered with small ocellated orange spots, and +are thus alike. In L. oegon the wings of the males are of a fine blue, +bordered with black, whilst those of the female are brown, with a similar +border, closely resembling the wings of L. agestis. Lastly, in L. arion +both sexes are of a blue colour and are very like, though in the female the +edges of the wings are rather duskier, with the black spots plainer; and in +a bright blue Indian species both sexes are still more alike. + +I have given the foregoing details in order to shew, in the first place, +that when the sexes of butterflies differ, the male as a general rule is +the more beautiful, and departs more from the usual type of colouring of +the group to which the species belongs. Hence in most groups the females +of the several species resemble each other much more closely than do the +males. In some cases, however, to which I shall hereafter allude, the +females are coloured more splendidly than the males. In the second place, +these details have been given to bring clearly before the mind that within +the same genus, the two sexes frequently present every gradation from no +difference in colour, to so great a difference that it was long before the +two were placed by entomologists in the same genus. In the third place, we +have seen that when the sexes nearly resemble each other, this appears due +either to the male having transferred his colours to the female, or to the +male having retained, or perhaps recovered, the primordial colours of the +group. It also deserves notice that in those groups in which the sexes +differ, the females usually somewhat resemble the males, so that when the +males are beautiful to an extraordinary degree, the females almost +invariably exhibit some degree of beauty. From the many cases of gradation +in the amount of difference between the sexes, and from the prevalence of +the same general type of coloration throughout the whole of the same group, +we may conclude that the causes have generally been the same which have +determined the brilliant colouring of the males alone of some species, and +of both sexes of other species. + +As so many gorgeous butterflies inhabit the tropics, it has often been +supposed that they owe their colours to the great heat and moisture of +these zones; but Mr. Bates (6. 'The Naturalist on the Amazons,' vol. i. +1863, p. 19.) has shown by the comparison of various closely-allied groups +of insects from the temperate and tropical regions, that this view cannot +be maintained; and the evidence becomes conclusive when brilliantly- +coloured males and plain-coloured females of the same species inhabit the +same district, feed on the same food, and follow exactly the same habits of +life. Even when the sexes resemble each other, we can hardly believe that +their brilliant and beautifully-arranged colours are the purposeless result +of the nature of the tissues and of the action of the surrounding +conditions. + +With animals of all kinds, whenever colour has been modified for some +special purpose, this has been, as far as we can judge, either for direct +or indirect protection, or as an attraction between the sexes. With many +species of butterflies the upper surfaces of the wings are obscure; and +this in all probability leads to their escaping observation and danger. +But butterflies would be particularly liable to be attacked by their +enemies when at rest; and most kinds whilst resting raise their wings +vertically over their backs, so that the lower surface alone is exposed to +view. Hence it is this side which is often coloured so as to imitate the +objects on which these insects commonly rest. Dr. Rossler, I believe, +first noticed the similarity of the closed wings of certain Vanessae and +other butterflies to the bark of trees. Many analogous and striking facts +could be given. The most interesting one is that recorded by Mr. Wallace +(7. See the interesting article in the 'Westminster Review,' July 1867, p. +10. A woodcut of the Kallima is given by Mr. Wallace in 'Hardwicke's +Science Gossip,' September 1867, p. 196.) of a common Indian and Sumatran +butterfly (Kallima) which disappears like magic when it settles on a bush; +for it hides its head and antennae between its closed wings, which, in +form, colour and veining, cannot be distinguished from a withered leaf with +its footstalk. In some other cases the lower surfaces of the wings are +brilliantly coloured, and yet are protective; thus in Thecla rubi the wings +when closed are of an emerald green, and resemble the young leaves of the +bramble, on which in spring this butterfly may often be seen seated. It is +also remarkable that in very many species in which the sexes differ greatly +in colour on their upper surface, the lower surface is closely similar or +identical in both sexes, and serves as a protection. (8. Mr. G. Fraser, +in 'Nature,' April 1871, p. 489.) + +Although the obscure tints both of the upper and under sides of many +butterflies no doubt serve to conceal them, yet we cannot extend this view +to the brilliant and conspicuous colours on the upper surface of such +species as our admiral and peacock Vanessae, our white cabbage-butterflies +(Pieris), or the great swallow-tail Papilio which haunts the open fens--for +these butterflies are thus rendered visible to every living creature. In +these species both sexes are alike; but in the common brimstone butterfly +(Gonepteryx rhamni), the male is of an intense yellow, whilst the female is +much paler; and in the orange-tip (Anthocharis cardamines) the males alone +have their wings tipped with bright orange. Both the males and females in +these cases are conspicuous, and it is not credible that their difference +in colour should stand in any relation to ordinary protection. Prof. +Weismann remarks (9. 'Einfluss der Isolirung auf die Artbildung,' 1872, p. +58.), that the female of one of the Lycaenae expands her brown wings when +she settles on the ground, and is then almost invisible; the male, on the +other hand, as if aware of the danger incurred from the bright blue of the +upper surface of his wings, rests with them closed; and this shows that the +blue colour cannot be in any way protective. Nevertheless, it is probable +that conspicuous colours are indirectly beneficial to many species, as a +warning that they are unpalatable. For in certain other cases, beauty has +been gained through the imitation of other beautiful species, which inhabit +the same district and enjoy an immunity from attack by being in some way +offensive to their enemies; but then we have to account for the beauty of +the imitated species. + +As Mr. Walsh has remarked to me, the females of our orange-tip butterfly, +above referred to, and of an American species (Anth. genutia) probably shew +us the primordial colours of the parent-species of the genus; for both +sexes of four or five widely-distributed species are coloured in nearly the +same manner. As in several previous cases, we may here infer that it is +the males of Anth. cardamines and genutia which have departed from the +usual type of the genus. In the Anth. sara from California, the orange- +tips to the wings have been partially developed in the female; but they are +paler than in the male, and slightly different in some other respects. In +an allied Indian form, the Iphias glaucippe, the orange-tips are fully +developed in both sexes. In this Iphias, as pointed out to me by Mr. A. +Butler, the under surface of the wings marvellously resembles a pale- +coloured leaf; and in our English orange-tip, the under surface resembles +the flower-head of the wild parsley, on which the butterfly often rests at +night. (10. See the interesting observations by T.W. Wood, 'The Student,' +Sept. 1868, p. 81.) The same reason which compels us to believe that the +lower surfaces have here been coloured for the sake of protection, leads us +to deny that the wings have been tipped with bright orange for the same +purpose, especially when this character is confined to the males. + +Most Moths rest motionless during the whole or greater part of the day with +their wings depressed; and the whole upper surface is often shaded and +coloured in an admirable manner, as Mr. Wallace has remarked, for escaping +detection. The front-wings of the Bombycidae and Noctuidae (11. Mr. +Wallace in 'Hardwicke's Science Gossip,' September 1867, p. 193.), when at +rest, generally overlap and conceal the hind-wings; so that the latter +might be brightly coloured without much risk; and they are in fact often +thus coloured. During flight, moths would often be able to escape from +their enemies; nevertheless, as the hind-wings are then fully exposed to +view, their bright colours must generally have been acquired at some little +risk. But the following fact shews how cautious we ought to be in drawing +conclusions on this head. The common Yellow Under-wings (Triphaena) often +fly about during the day or early evening, and are then conspicuous from +the colour of their hind-wings. It would naturally be thought that this +would be a source of danger; but Mr. J. Jenner Weir believes that it +actually serves them as a means of escape, for birds strike at these +brightly coloured and fragile surfaces, instead of at the body. For +instance, Mr. Weir turned into his aviary a vigorous specimen of Triphaena +pronuba, which was instantly pursued by a robin; but the bird's attention +being caught by the coloured wings, the moth was not captured until after +about fifty attempts, and small portions of the wings were repeatedly +broken off. He tried the same experiment, in the open air, with a swallow +and T. fimbria; but the large size of this moth probably interfered with +its capture. (12. See also, on this subject, Mr. Weir's paper in +'Transactions, Entomological Society,' 1869, p. 23.) We are thus reminded +of a statement made by Mr. Wallace (13. 'Westminster Review,' July 1867, +p. 16.), namely, that in the Brazilian forests and Malayan islands, many +common and highly-decorated butterflies are weak flyers, though furnished +with a broad expanse of wing; and they "are often captured with pierced and +broken wings, as if they had been seized by birds, from which they had +escaped: if the wings had been much smaller in proportion to the body, it +seems probable that the insect would more frequently have been struck or +pierced in a vital part, and thus the increased expanse of the wings may +have been indirectly beneficial." + +DISPLAY. + +The bright colours of many butterflies and of some moths are specially +arranged for display, so that they may be readily seen. During the night +colours are not visible, and there can be no doubt that the nocturnal +moths, taken as a body, are much less gaily decorated than butterflies, all +of which are diurnal in their habits. But the moths of certain families, +such as the Zygaenidae, several Sphingidae, Uraniidae, some Arctiidae and +Saturniidae, fly about during the day or early evening, and many of these +are extremely beautiful, being far brighter coloured than the strictly +nocturnal kinds. A few exceptional cases, however, of bright-coloured +nocturnal species have been recorded. (14. For instance, Lithosia; but +Prof. Westwood ('Modern Class. of Insects,' vol. ii. p. 390) seems +surprised at this case. On the relative colours of diurnal and nocturnal +Lepidoptera, see ibid. pp. 333 and 392; also Harris, 'Treatise on the +Insects of New England,' 1842, p. 315.) + +There is evidence of another kind in regard to display. Butterflies, as +before remarked, elevate their wings when at rest, but whilst basking in +the sunshine often alternately raise and depress them, thus exposing both +surfaces to full view; and although the lower surface is often coloured in +an obscure manner as a protection, yet in many species it is as highly +decorated as the upper surface, and sometimes in a very different manner. +In some tropical species the lower surface is even more brilliantly +coloured than the upper. (15. Such differences between the upper and +lower surfaces of the wings of several species of Papilio may be seen in +the beautiful plates to Mr. Wallace's 'Memoir on the Papilionidae of the +Malayan Region,' in 'Transactions of the Linnean Society,' vol. xxv. part +i. 1865.) In the English fritillaries (Argynnis) the lower surface alone +is ornamented with shining silver. Nevertheless, as a general rule, the +upper surface, which is probably more fully exposed, is coloured more +brightly and diversely than the lower. Hence the lower surface generally +affords to entomologists the more useful character for detecting the +affinities of the various species. Fritz Müller informs me that three +species of Castnia are found near his house in S. Brazil: of two of them +the hind-wings are obscure, and are always covered by the front-wings when +these butterflies are at rest; but the third species has black hind-wings, +beautifully spotted with red and white, and these are fully expanded and +displayed whenever the butterfly rests. Other such cases could be added. + +If we now turn to the enormous group of moths, which, as I hear from Mr. +Stainton, do not habitually expose the under surface of their wings to full +view, we find this side very rarely coloured with a brightness greater +than, or even equal to, that of the upper side. Some exceptions to the +rule, either real or apparent, must be noticed, as the case of Hypopyra. +(16. See Mr. Wormald on this moth: 'Proceedings of the Entomological +Society,' March 2, 1868.) Mr. Trimen informs me that in Guenee's great +work, three moths are figured, in which the under surface is much the more +brilliant. For instance, in the Australian Gastrophora the upper surface +of the fore-wing is pale greyish-ochreous, while the lower surface is +magnificently ornamented by an ocellus of cobalt-blue, placed in the midst +of a black mark, surrounded by orange-yellow, and this by bluish-white. +But the habits of these three moths are unknown; so that no explanation can +be given of their unusual style of colouring. Mr. Trimen also informs me +that the lower surface of the wings in certain other Geometrae (17. See +also an account of the S. American genus Erateina (one of the Geometrae) in +'Transactions, Ent. Soc.' new series, vol. v. pl. xv. and xvi.) and +quadrifid Noctuae are either more variegated or more brightly-coloured than +the upper surface; but some of these species have the habit of "holding +their wings quite erect over their backs, retaining them in this position +for a considerable time," and thus exposing the under surface to view. +Other species, when settled on the ground or herbage, now and then suddenly +and slightly lift up their wings. Hence the lower surface of the wings +being brighter than the upper surface in certain moths is not so anomalous +as it at first appears. The Saturniidae include some of the most beautiful +of all moths, their wings being decorated, as in our British Emperor moth, +with fine ocelli; and Mr. T.W. Wood (18. 'Proc Ent. Soc. of London,' July +6, 1868, p. xxvii.) observes that they resemble butterflies in some of +their movements; "for instance, in the gentle waving up and down of the +wings as if for display, which is more characteristic of diurnal than of +nocturnal Lepidoptera." + +It is a singular fact that no British moths which are brilliantly coloured, +and, as far as I can discover, hardly any foreign species, differ much in +colour according to sex; though this is the case with many brilliant +butterflies. The male, however, of one American moth, the Saturnia Io, is +described as having its fore-wings deep yellow, curiously marked with +purplish-red spots; whilst the wings of the female are purple-brown, marked +with grey lines. (19. Harris, 'Treatise,' etc., edited by Flint, 1862, p. +395.) The British moths which differ sexually in colour are all brown, or +of various dull yellow tints, or nearly white. In several species the +males are much darker than the females (20. For instance, I observe in my +son's cabinet that the males are darker than the females in the Lasiocampa +quercus, Odonestis potatoria, Hypogymna dispar, Dasychira pudibunda, and +Cycnia mendica. In this latter species the difference in colour between +the two sexes is strongly marked; and Mr. Wallace informs me that we here +have, as he believes, an instance of protective mimicry confined to one +sex, as will hereafter be more fully explained. The white female of the +Cycnia resembles the very common Spilosoma menthrasti, both sexes of which +are white; and Mr. Stainton observed that this latter moth was rejected +with utter disgust by a whole brood of young turkeys, which were fond of +eating other moths; so that if the Cycnia was commonly mistaken by British +birds for the Spilosoma, it would escape being devoured, and its white +deceptive colour would thus be highly beneficial.), and these belong to +groups which generally fly about during the afternoon. On the other hand, +in many genera, as Mr. Stainton informs me, the males have the hind-wings +whiter than those of the female--of which fact Agrotis exclamationis offers +a good instance. In the Ghost Moth (Hepialus humuli) the difference is +more strongly marked; the males being white, and the females yellow with +darker markings. (21. It is remarkable, that in the Shetland Islands the +male of this moth, instead of differing widely from the female, frequently +resembles her closely in colour (see Mr. MacLachlan, 'Transactions, +Entomological Society,' vol. ii. 1866, p. 459). Mr. G. Fraser suggests +('Nature,' April 1871, p. 489) that at the season of the year when the +ghost-moth appears in these northern islands, the whiteness of the males +would not be needed to render them visible to the females in the twilight +night.) It is probable that in these cases the males are thus rendered +more conspicuous, and more easily seen by the females whilst flying about +in the dusk. + +From the several foregoing facts it is impossible to admit that the +brilliant colours of butterflies, and of some few moths, have commonly been +acquired for the sake of protection. We have seen that their colours and +elegant patterns are arranged and exhibited as if for display. Hence I am +led to believe that the females prefer or are most excited by the more +brilliant males; for on any other supposition the males would, as far as we +can see, be ornamented to no purpose. We know that ants and certain +Lamellicorn beetles are capable of feeling an attachment for each other, +and that ants recognise their fellows after an interval of several months. +Hence there is no abstract improbability in the Lepidoptera, which probably +stand nearly or quite as high in the scale as these insects, having +sufficient mental capacity to admire bright colours. They certainly +discover flowers by colour. The Humming-bird Sphinx may often be seen to +swoop down from a distance on a bunch of flowers in the midst of green +foliage; and I have been assured by two persons abroad, that these moths +repeatedly visit flowers painted on the walls of a room, and vainly +endeavour to insert their proboscis into them. Fritz Müller informs me +that several kinds of butterflies in S. Brazil shew an unmistakable +preference for certain colours over others: he observed that they very +often visited the brilliant red flowers of five or six genera of plants, +but never the white or yellow flowering species of the same and other +genera, growing in the same garden; and I have received other accounts to +the same effect. As I hear from Mr. Doubleday, the common white butterfly +often flies down to a bit of paper on the ground, no doubt mistaking it for +one of its own species. Mr. Collingwood (22. 'Rambles of a Naturalist in +the Chinese Seas,' 1868, p. 182.) in speaking of the difficulty in +collecting certain butterflies in the Malay Archipelago, states that "a +dead specimen pinned upon a conspicuous twig will often arrest an insect of +the same species in its headlong flight, and bring it down within easy +reach of the net, especially if it be of the opposite sex." + +The courtship of butterflies is, as before remarked, a prolonged affair. +The males sometimes fight together in rivalry; and many may be seen +pursuing or crowding round the same female. Unless, then, the females +prefer one male to another, the pairing must be left to mere chance, and +this does not appear probable. If, on the other band, the females +habitually, or even occasionally, prefer the more beautiful males, the +colours of the latter will have been rendered brighter by degrees, and will +have been transmitted to both sexes or to one sex, according to the law of +inheritance which has prevailed. The process of sexual selection will have +been much facilitated, if the conclusion can be trusted, arrived at from +various kinds of evidence in the supplement to the ninth chapter; namely, +that the males of many Lepidoptera, at least in the imago state, greatly +exceed the females in number. + +Some facts, however, are opposed to the belief that female butterflies +prefer the more beautiful males; thus, as I have been assured by several +collectors, fresh females may frequently be seen paired with battered, +faded, or dingy males; but this is a circumstance which could hardly fail +often to follow from the males emerging from their cocoons earlier than the +females. With moths of the family of the Bombycidae, the sexes pair +immediately after assuming the imago state; for they cannot feed, owing to +the rudimentary condition of their mouths. The females, as several +entomologists have remarked to me, lie in an almost torpid state, and +appear not to evince the least choice in regard to their partners. This is +the case with the common silk-moth (B. mori), as I have been told by some +continental and English breeders. Dr. Wallace, who has had great +experience in breeding Bombyx cynthia, is convinced that the females evince +no choice or preference. He has kept above 300 of these moths together, +and has often found the most vigorous females mated with stunted males. +The reverse appears to occur seldom; for, as he believes, the more vigorous +males pass over the weakly females, and are attracted by those endowed with +most vitality. Nevertheless, the Bombycidae, though obscurely-coloured, +are often beautiful to our eyes from their elegant and mottled shades. + +I have as yet only referred to the species in which the males are brighter +coloured than the females, and I have attributed their beauty to the +females for many generations having chosen and paired with the more +attractive males. But converse cases occur, though rarely, in which the +females are more brilliant than the males; and here, as I believe, the +males have selected the more beautiful females, and have thus slowly added +to their beauty. We do not know why in various classes of animals the +males of some few species have selected the more beautiful females instead +of having gladly accepted any female, as seems to be the general rule in +the animal kingdom: but if, contrary to what generally occurs with the +Lepidoptera, the females were much more numerous than the males, the latter +would be likely to pick out the more beautiful females. Mr. Butler shewed +me several species of Callidryas in the British Museum, in some of which +the females equalled, and in others greatly surpassed the males in beauty; +for the females alone have the borders of their wings suffused with crimson +and orange, and spotted with black. The plainer males of these species +closely resemble each other, shewing that here the females have been +modified; whereas in those cases, where the males are the more ornate, it +is these which have been modified, the females remaining closely alike. + +In England we have some analogous cases, though not so marked. The females +alone of two species of Thecla have a bright-purple or orange patch on +their fore-wings. In Hipparchia the sexes do not differ much; but it is +the female of H. janira which has a conspicuous light-brown patch on her +wings; and the females of some of the other species are brighter coloured +than their males. Again, the females of Colias edusa and hyale have +"orange or yellow spots on the black marginal border, represented in the +males only by thin streaks"; and in Pieris it is the females which "are +ornamented with black spots on the fore-wings, and these are only partially +present in the males." Now the males of many butterflies are known to +support the females during their marriage flight; but in the species just +named it is the females which support the males; so that the part which the +two sexes play is reversed, as is their relative beauty. Throughout the +animal kingdom the males commonly take the more active share in wooing, and +their beauty seems to have been increased by the females having accepted +the more attractive individuals; but with these butterflies, the females +take the more active part in the final marriage ceremony, so that we may +suppose that they likewise do so in the wooing; and in this case we can +understand how it is that they have been rendered the more beautiful. Mr. +Meldola, from whom the foregoing statements have been taken, says in +conclusion: "Though I am not convinced of the action of sexual selection +in producing the colours of insects, it cannot be denied that these facts +are strikingly corroborative of Mr. Darwin's views." (23. 'Nature,' April +27, 1871, p. 508. Mr. Meldola quotes Donzel, in 'Soc. Ent. de France,' +1837, p. 77, on the flight of butterflies whilst pairing. See also Mr. G. +Fraser, in 'Nature,' April 20, 1871, p. 489, on the sexual differences of +several British butterflies.) + +As sexual selection primarily depends on variability, a few words must be +added on this subject. In respect to colour there is no difficulty, for +any number of highly variable Lepidoptera could be named. One good +instance will suffice. Mr. Bates shewed me a whole series of specimens of +Papilio sesostris and P. childrenae; in the latter the males varied much in +the extent of the beautifully enamelled green patch on the fore-wings, and +in the size of the white mark, and of the splendid crimson stripe on the +hind-wings; so that there was a great contrast amongst the males between +the most and the least gaudy. The male of Papilio sesostris is much less +beautiful than of P. childrenae; and it likewise varies a little in the +size of the green patch on the fore-wings, and in the occasional appearance +of the small crimson stripe on the hind-wings, borrowed, as it would seem, +from its own female; for the females of this and of many other species in +the Aeneas group possess this crimson stripe. Hence between the brightest +specimens of P. sesostris and the dullest of P. childrenae, there was but a +small interval; and it was evident that as far as mere variability is +concerned, there would be no difficulty in permanently increasing the +beauty of either species by means of selection. The variability is here +almost confined to the male sex; but Mr. Wallace and Mr. Bates have shewn +(24. Wallace on the Papilionidae of the Malayan Region, in 'Transact. +Linn. Soc.' vol. xxv. 1865, pp. 8, 36. A striking case of a rare variety, +strictly intermediate between two other well-marked female varieties, is +given by Mr. Wallace. See also Mr. Bates, in 'Proc. Entomolog. Soc.' Nov. +19, 1866, p. xl.) that the females of some species are extremely variable, +the males being nearly constant. In a future chapter I shall have occasion +to shew that the beautiful eye-like spots, or ocelli, found on the wings of +many Lepidoptera, are eminently variable. I may here add that these ocelli +offer a difficulty on the theory of sexual selection; for though appearing +to us so ornamental, they are never present in one sex and absent in the +other, nor do they ever differ much in the two sexes. (25. Mr. Bates was +so kind as to lay this subject before the Entomological Society, and I have +received answers to this effect from several entomologists.) This fact is +at present inexplicable; but if it should hereafter be found that the +formation of an ocellus is due to some change in the tissues of the wings, +for instance, occurring at a very early period of development, we might +expect, from what we know of the laws of inheritance, that it would be +transmitted to both sexes, though arising and perfected in one sex alone. + +On the whole, although many serious objections may be urged, it seems +probable that most of the brilliantly-coloured species of Lepidoptera owe +their colours to sexual selection, excepting in certain cases, presently to +be mentioned, in which conspicuous colours have been gained through mimicry +as a protection. From the ardour of the male throughout the animal +kingdom, he is generally willing to accept any female; and it is the female +which usually exerts a choice. Hence, if sexual selection has been +efficient with the Lepidoptera, the male, when the sexes differ, ought to +be the more brilliantly coloured, and this undoubtedly is the case. When +both sexes are brilliantly coloured and resemble each other, the characters +acquired by the males appear to have been transmitted to both. We are led +to this conclusion by cases, even within the same genus, of gradation from +an extraordinary amount of difference to identity in colour between the two +sexes. + +But it may be asked whether the difference in colour between the sexes may +not be accounted for by other means besides sexual selection. Thus the +males and females of the same species of butterfly are in several cases +known (26. H.W. Bates, 'The Naturalist on the Amazons,' vol. ii. 1863, p. +228. A.R. Wallace, in 'Transactions, Linnean Society,' vol. xxv. 1865, p. +10.) to inhabit different stations, the former commonly basking in the +sunshine, the latter haunting gloomy forests. It is therefore possible +that different conditions of life may have acted directly on the two sexes; +but this is not probable (27. On this whole subject see 'The Variation of +Animals and Plants under Domestication,' 1868, vol. ii. chap. xxiii.) as in +the adult state they are exposed to different conditions during a very +short period; and the larvae of both are exposed to the same conditions. +Mr. Wallace believes that the difference between the sexes is due not so +much to the males having been modified, as to the females having in all or +almost all cases acquired dull colours for the sake of protection. It +seems to me, on the contrary, far more probable that it is the males which +have been chiefly modified through sexual selection, the females having +been comparatively little changed. We can thus understand how it is that +the females of allied species generally resemble one another so much more +closely than do the males. They thus shew us approximately the primordial +colouring of the parent-species of the group to which they belong. They +have, however, almost always been somewhat modified by the transfer to them +of some of the successive variations, through the accumulation of which the +males were rendered beautiful. But I do not wish to deny that the females +alone of some species may have been specially modified for protection. In +most cases the males and females of distinct species will have been exposed +during their prolonged larval state to different conditions, and may have +been thus affected; though with the males any slight change of colour thus +caused will generally have been masked by the brilliant tints gained +through sexual selection. When we treat of Birds, I shall have to discuss +the whole question, as to how far the differences in colour between the +sexes are due to the males having been modified through sexual selection +for ornamental purposes, or to the females having been modified through +natural selection for the sake of protection, so that I will here say but +little on the subject. + +In all the cases in which the more common form of equal inheritance by both +sexes has prevailed, the selection of bright-coloured males would tend to +make the females bright-coloured; and the selection of dull-coloured +females would tend to make the males dull. If both processes were carried +on simultaneously, they would tend to counteract each other; and the final +result would depend on whether a greater number of females from being well +protected by obscure colours, or a greater number of males by being +brightly-coloured and thus finding partners, succeeded in leaving more +numerous offspring. + +In order to account for the frequent transmission of characters to one sex +alone, Mr. Wallace expresses his belief that the more common form of equal +inheritance by both sexes can be changed through natural selection into +inheritance by one sex alone, but in favour of this view I can discover no +evidence. We know from what occurs under domestication that new characters +often appear, which from the first are transmitted to one sex alone; and by +the selection of such variations there would not be the slightest +difficulty in giving bright colours to the males alone, and at the same +time or subsequently, dull colours to the females alone. In this manner +the females of some butterflies and moths have, it is probable, been +rendered inconspicuous for the sake of protection, and widely different +from their males. + +I am, however, unwilling without distinct evidence to admit that two +complex processes of selection, each requiring the transference of new +characters to one sex alone, have been carried on with a multitude of +species,--that the males have been rendered more brilliant by beating their +rivals, and the females more dull-coloured by having escaped from their +enemies. The male, for instance, of the common brimstone butterfly +(Gonepteryx), is of a far more intense yellow than the female, though she +is equally conspicuous; and it does not seem probable that she specially +acquired her pale tints as a protection, though it is probable that the +male acquired his bright colours as a sexual attraction. The female of +Anthocharis cardamines does not possess the beautiful orange wing-tips of +the male; consequently she closely resembles the white butterflies (Pieris) +so common in our gardens; but we have no evidence that this resemblance is +beneficial to her. As, on the other hand, she resembles both sexes of +several other species of the genus inhabiting various quarters of the +world, it is probable that she has simply retained to a large extent her +primordial colours. + +Finally, as we have seen, various considerations lead to the conclusion +that with the greater number of brilliantly-coloured Lepidoptera it is the +male which has been chiefly modified through sexual selection; the amount +of difference between the sexes mostly depending on the form of inheritance +which has prevailed. Inheritance is governed by so many unknown laws or +conditions, that it seems to us to act in a capricious manner (28. The +'Variation of Animals and Plants under Domestication,' vol. ii. chap. xii. +p. 17.); and we can thus, to a certain extent, understand how it is that +with closely allied species the sexes either differ to an astonishing +degree, or are identical in colour. As all the successive steps in the +process of variation are necessarily transmitted through the female, a +greater or less number of such steps might readily become developed in her; +and thus we can understand the frequent gradations from an extreme +difference to none at all between the sexes of allied species. These cases +of gradation, it may be added, are much too common to favour the +supposition that we here see females actually undergoing the process of +transition and losing their brightness for the sake of protection; for we +have every reason to conclude that at any one time the greater number of +species are in a fixed condition. + +MIMICRY. + +This principle was first made clear in an admirable paper by Mr. Bates (29. +'Transact. Linn. Soc.' vol. xxiii. 1862, p. 495.), who thus threw a flood +of light on many obscure problems. It had previously been observed that +certain butterflies in S. America belonging to quite distinct families, +resembled the Heliconidae so closely in every stripe and shade of colour, +that they could not be distinguished save by an experienced entomologist. +As the Heliconidae are coloured in their usual manner, whilst the others +depart from the usual colouring of the groups to which they belong, it is +clear that the latter are the imitators, and the Heliconidae the imitated. +Mr. Bates further observed that the imitating species are comparatively +rare, whilst the imitated abound, and that the two sets live mingled +together. From the fact of the Heliconidae being conspicuous and beautiful +insects, yet so numerous in individuals and species, he concluded that they +must be protected from the attacks of enemies by some secretion or odour; +and this conclusion has now been amply confirmed (30. 'Proc. Entomological +Soc.' Dec. 3, 1866, p. xlv.), especially by Mr. Belt. Hence Mr. Bates +inferred that the butterflies which imitate the protected species have +acquired their present marvellously deceptive appearance through variation +and natural selection, in order to be mistaken for the protected kinds, and +thus to escape being devoured. No explanation is here attempted of the +brilliant colours of the imitated, but only of the imitating butterflies. +We must account for the colours of the former in the same general manner, +as in the cases previously discussed in this chapter. Since the +publication of Mr. Bates' paper, similar and equally striking facts have +been observed by Mr. Wallace in the Malayan region, by Mr. Trimen in South +Africa, and by Mr. Riley in the United States. (31. Wallace, 'Transact. +Linn. Soc.' vol. xxv. 1865 p. i.; also, 'Transact. Ent. Soc.' vol. iv. (3rd +series), 1867, p. 301. Trimen, 'Linn. Transact.' vol. xxvi. 1869, p. 497. +Riley, 'Third Annual Report on the Noxious Insects of Missouri,' 1871, pp. +163-168. This latter essay is valuable, as Mr. Riley here discusses all +the objections which have been raised against Mr. Bates's theory.) + +As some writers have felt much difficulty in understanding how the first +steps in the process of mimicry could have been effected through natural +selection, it may be well to remark that the process probably commenced +long ago between forms not widely dissimilar in colour. In this case even +a slight variation would be beneficial, if it rendered the one species more +like the other; and afterwards the imitated species might be modified to an +extreme degree through sexual selection or other means, and if the changes +were gradual, the imitators might easily be led along the same track, until +they differed to an equally extreme degree from their original condition; +and they would thus ultimately assume an appearance or colouring wholly +unlike that of the other members of the group to which they belonged. It +should also be remembered that many species of Lepidoptera are liable to +considerable and abrupt variations in colour. A few instances have been +given in this chapter; and many more may be found in the papers of Mr. +Bates and Mr. Wallace. + +With several species the sexes are alike, and imitate the two sexes of +another species. But Mr. Trimen gives, in the paper already referred to, +three cases in which the sexes of the imitated form differ from each other +in colour, and the sexes of the imitating form differ in a like manner. +Several cases have also been recorded where the females alone imitate +brilliantly-coloured and protected species, the males retaining "the normal +aspect of their immediate congeners." It is here obvious that the +successive variations by which the female has been modified have been +transmitted to her alone. It is, however, probable that some of the many +successive variations would have been transmitted to, and developed in, the +males had not such males been eliminated by being thus rendered less +attractive to the females; so that only those variations were preserved +which were from the first strictly limited in their transmission to the +female sex. We have a partial illustration of these remarks in a statement +by Mr. Belt (32. 'The Naturalist in Nicaragua,' 1874, p. 385.); that the +males of some of the Leptalides, which imitate protected species, still +retain in a concealed manner some of their original characters. Thus in +the males "the upper half of the lower wing is of a pure white, whilst all +the rest of the wings is barred and spotted with black, red and yellow, +like the species they mimic. The females have not this white patch, and +the males usually conceal it by covering it with the upper wing, so that I +cannot imagine its being of any other use to them than as an attraction in +courtship, when they exhibit it to the females, and thus gratify their +deep-seated preference for the normal colour of the Order to which the +Leptalides belong." + +BRIGHT COLOURS OF CATERPILLARS. + +Whilst reflecting on the beauty of many butterflies, it occurred to me that +some caterpillars were splendidly coloured; and as sexual selection could +not possibly have here acted, it appeared rash to attribute the beauty of +the mature insect to this agency, unless the bright colours of their larvae +could be somehow explained. In the first place, it may be observed that +the colours of caterpillars do not stand in any close correlation with +those of the mature insect. Secondly, their bright colours do not serve in +any ordinary manner as a protection. Mr. Bates informs me, as an instance +of this, that the most conspicuous caterpillar which he ever beheld (that +of a Sphinx) lived on the large green leaves of a tree on the open llanos +of South America; it was about four inches in length, transversely banded +with black and yellow, and with its head, legs, and tail of a bright red. +Hence it caught the eye of any one who passed by, even at the distance of +many yards, and no doubt that of every passing bird. + +I then applied to Mr. Wallace, who has an innate genius for solving +difficulties. After some consideration he replied: "Most caterpillars +require protection, as may be inferred from some kinds being furnished with +spines or irritating hairs, and from many being coloured green like the +leaves on which they feed, or being curiously like the twigs of the trees +on which they live." Another instance of protection, furnished me by Mr. +J. Mansel Weale, may be added, namely, that there is a caterpillar of a +moth which lives on the mimosas in South Africa, and fabricates for itself +a case quite indistinguishable from the surrounding thorns. From such +considerations Mr. Wallace thought it probable that conspicuously coloured +caterpillars were protected by having a nauseous taste; but as their skin +is extremely tender, and as their intestines readily protrude from a wound, +a slight peck from the beak of a bird would be as fatal to them as if they +had been devoured. Hence, as Mr. Wallace remarks, "distastefulness alone +would be insufficient to protect a caterpillar unless some outward sign +indicated to its would-be destroyer that its prey was a disgusting morsel." +Under these circumstances it would be highly advantageous to a caterpillar +to be instantaneously and certainly recognised as unpalatable by all birds +and other animals. Thus the most gaudy colours would be serviceable, and +might have been gained by variation and the survival of the most easily- +recognised individuals. + +This hypothesis appears at first sight very bold, but when it was brought +before the Entomological Society (33. 'Proceedings, Entomological +Society,' Dec. 3, 1866, p. xlv. and March 4, 1867, p. lxxx.) it was +supported by various statements; and Mr. J. Jenner Weir, who keeps a large +number of birds in an aviary, informs me that he has made many trials, and +finds no exception to the rule, that all caterpillars of nocturnal and +retiring habits with smooth skins, all of a green colour, and all which +imitate twigs, are greedily devoured by his birds. The hairy and spinose +kinds are invariably rejected, as were four conspicuously-coloured species. +When the birds rejected a caterpillar, they plainly shewed, by shaking +their heads, and cleansing their beaks, that they were disgusted by the +taste. (34. See Mr. J. Jenner Weir's paper on Insects and Insectivorous +Birds, in 'Transact. Ent. Soc.' 1869, p. 21; also Mr. Butler's paper, ibid. +p. 27. Mr. Riley has given analogous facts in the 'Third Annual Report on +the Noxious Insects of Missouri,' 1871, p. 148. Some opposed cases are, +however, given by Dr. Wallace and M. H. d'Orville; see 'Zoological Record,' +1869, p. 349.) Three conspicuous kinds of caterpillars and moths were also +given to some lizards and frogs, by Mr. A. Butler, and were rejected, +though other kinds were eagerly eaten. Thus the probability of Mr. +Wallace's view is confirmed, namely, that certain caterpillars have been +made conspicuous for their own good, so as to be easily recognised by their +enemies, on nearly the same principle that poisons are sold in coloured +bottles by druggists for the good of man. We cannot, however, at present +thus explain the elegant diversity in the colours of many caterpillars; but +any species which had at some former period acquired a dull, mottled, or +striped appearance, either in imitation of surrounding objects, or from the +direct action of climate, etc., almost certainly would not become uniform +in colour, when its tints were rendered intense and bright; for in order to +make a caterpillar merely conspicuous, there would be no selection in any +definite direction. + +SUMMARY AND CONCLUDING REMARKS ON INSECTS. + +Looking back to the several Orders, we see that the sexes often differ in +various characters, the meaning of which is not in the least understood. +The sexes, also, often differ in their organs of sense and means of +locomotion, so that the males may quickly discover and reach the females. +They differ still oftener in the males possessing diversified contrivances +for retaining the females when found. We are, however, here concerned only +in a secondary degree with sexual differences of these kinds. + +In almost all the Orders, the males of some species, even of weak and +delicate kinds, are known to be highly pugnacious; and some few are +furnished with special weapons for fighting with their rivals. But the law +of battle does not prevail nearly so widely with insects as with the higher +animals. Hence it probably arises, that it is in only a few cases that the +males have been rendered larger and stronger than the females. On the +contrary, they are usually smaller, so that they may be developed within a +shorter time, to be ready in large numbers for the emergence of the +females. + +In two families of the Homoptera and in three of the Orthoptera, the males +alone possess sound-producing organs in an efficient state. These are used +incessantly during the breeding-season, not only for calling the females, +but apparently for charming or exciting them in rivalry with other males. +No one who admits the agency of selection of any kind, will, after reading +the above discussion, dispute that these musical instruments have been +acquired through sexual selection. In four other Orders the members of one +sex, or more commonly of both sexes, are provided with organs for producing +various sounds, which apparently serve merely as call-notes. When both +sexes are thus provided, the individuals which were able to make the +loudest or most continuous noise would gain partners before those which +were less noisy, so that their organs have probably been gained through +sexual selection. It is instructive to reflect on the wonderful diversity +of the means for producing sound, possessed by the males alone, or by both +sexes, in no less than six Orders. We thus learn how effectual sexual +selection has been in leading to modifications which sometimes, as with the +Homoptera, relate to important parts of the organisation. + +From the reasons assigned in the last chapter, it is probable that the +great horns possessed by the males of many Lamellicorn, and some other +beetles, have been acquired as ornaments. From the small size of insects, +we are apt to undervalue their appearance. If we could imagine a male +Chalcosoma (Fig. 16), with its polished bronzed coat of mail, and its vast +complex horns, magnified to the size of a horse, or even of a dog, it would +be one of the most imposing animals in the world. + +The colouring of insects is a complex and obscure subject. When the male +differs slightly from the female, and neither are brilliantly-coloured, it +is probable that the sexes have varied in a slightly different manner, and +that the variations have been transmitted by each sex to the same without +any benefit or evil thus accruing. When the male is brilliantly-coloured +and differs conspicuously from the female, as with some dragon-flies and +many butterflies, it is probable that he owes his colours to sexual +selection; whilst the female has retained a primordial or very ancient type +of colouring, slightly modified by the agencies before explained. But in +some cases the female has apparently been made obscure by variations +transmitted to her alone, as a means of direct protection; and it is almost +certain that she has sometimes been made brilliant, so as to imitate other +protected species inhabiting the same district. When the sexes resemble +each other and both are obscurely coloured, there is no doubt that they +have been in a multitude of cases so coloured for the sake of protection. +So it is in some instances when both are brightly-coloured, for they thus +imitate protected species, or resemble surrounding objects such as flowers; +or they give notice to their enemies that they are unpalatable. In other +cases in which the sexes resemble each other and are both brilliant, +especially when the colours are arranged for display, we may conclude that +they have been gained by the male sex as an attraction, and have been +transferred to the female. We are more especially led to this conclusion +whenever the same type of coloration prevails throughout a whole group, and +we find that the males of some species differ widely in colour from the +females, whilst others differ slightly or not at all with intermediate +gradations connecting these extreme states. + +In the same manner as bright colours have often been partially transferred +from the males to the females, so it has been with the extraordinary horns +of many Lamellicorn and some other beetles. So again, the sound-producing +organs proper to the males of the Homoptera and Orthoptera have generally +been transferred in a rudimentary, or even in a nearly perfect condition, +to the females; yet not sufficiently perfect to be of any use. It is also +an interesting fact, as bearing on sexual selection, that the stridulating +organs of certain male Orthoptera are not fully developed until the last +moult; and that the colours of certain male dragon-flies are not fully +developed until some little time after their emergence from the pupal +state, and when they are ready to breed. + +Sexual selection implies that the more attractive individuals are preferred +by the opposite sex; and as with insects, when the sexes differ, it is the +male which, with some rare exceptions, is the more ornamented, and departs +more from the type to which the species belongs;--and as it is the male +which searches eagerly for the female, we must suppose that the females +habitually or occasionally prefer the more beautiful males, and that these +have thus acquired their beauty. That the females in most or all the +Orders would have the power of rejecting any particular male, is probable +from the many singular contrivances possessed by the males, such as great +jaws, adhesive cushions, spines, elongated legs, etc., for seizing the +female; for these contrivances show that there is some difficulty in the +act, so that her concurrence would seem necessary. Judging from what we +know of the perceptive powers and affections of various insects, there is +no antecedent improbability in sexual selection having come largely into +play; but we have as yet no direct evidence on this head, and some facts +are opposed to the belief. Nevertheless, when we see many males pursuing +the same female, we can hardly believe that the pairing is left to blind +chance--that the female exerts no choice, and is not influenced by the +gorgeous colours or other ornaments with which the male is decorated. + +If we admit that the females of the Homoptera and Orthoptera appreciate the +musical tones of their male partners, and that the various instruments have +been perfected through sexual selection, there is little improbability in +the females of other insects appreciating beauty in form or colour, and +consequently in such characters having been thus gained by the males. But +from the circumstance of colour being so variable, and from its having been +so often modified for the sake of protection, it is difficult to decide in +how large a proportion of cases sexual selection has played a part. This +is more especially difficult in those Orders, such as Orthoptera, +Hymenoptera, and Coleoptera, in which the two sexes rarely differ much in +colour; for we are then left to mere analogy. With the Coleoptera, +however, as before remarked, it is in the great Lamellicorn group, placed +by some authors at the head of the Order, and in which we sometimes see a +mutual attachment between the sexes, that we find the males of some species +possessing weapons for sexual strife, others furnished with wonderful +horns, many with stridulating organs, and others ornamented with splendid +metallic tints. Hence it seems probable that all these characters have +been gained through the same means, namely sexual selection. With +butterflies we have the best evidence, as the males sometimes take pains to +display their beautiful colours; and we cannot believe that they would act +thus, unless the display was of use to them in their courtship. + +When we treat of Birds, we shall see that they present in their secondary +sexual characters the closest analogy with insects. Thus, many male birds +are highly pugnacious, and some are furnished with special weapons for +fighting with their rivals. They possess organs which are used during the +breeding-season for producing vocal and instrumental music. They are +frequently ornamented with combs, horns, wattles and plumes of the most +diversified kinds, and are decorated with beautiful colours, all evidently +for the sake of display. We shall find that, as with insects, both sexes +in certain groups are equally beautiful, and are equally provided with +ornaments which are usually confined to the male sex. In other groups both +sexes are equally plain-coloured and unornamented. Lastly, in some few +anomalous cases, the females are more beautiful than the males. We shall +often find, in the same group of birds, every gradation from no difference +between the sexes, to an extreme difference. We shall see that female +birds, like female insects, often possess more or less plain traces or +rudiments of characters which properly belong to the males and are of use +only to them. The analogy, indeed, in all these respects between birds and +insects is curiously close. Whatever explanation applies to the one class +probably applies to the other; and this explanation, as we shall hereafter +attempt to shew in further detail, is sexual selection. + + +CHAPTER XII. + +SECONDARY SEXUAL CHARACTERS OF FISHES, AMPHIBIANS, AND REPTILES. + +FISHES: Courtship and battles of the males--Larger size of the females-- +Males, bright colours and ornamental appendages; other strange characters-- +Colours and appendages acquired by the males during the breeding-season +alone--Fishes with both sexes brilliantly coloured--Protective colours--The +less conspicuous colours of the female cannot be accounted for on the +principle of protection--Male fishes building nests, and taking charge of +the ova and young. + +AMPHIBIANS: Differences in structure and colour between the sexes--Vocal +organs. + +REPTILES: Chelonians--Crocodiles--Snakes, colours in some cases +protective--Lizards, battles of--Ornamental appendages--Strange differences +in structure between the sexes--Colours--Sexual differences almost as great +as with birds. + +We have now arrived at the great sub-kingdom of the Vertebrata, and will +commence with the lowest class, that of fishes. The males of Plagiostomous +fishes (sharks, rays) and of Chimaeroid fishes are provided with claspers +which serve to retain the female, like the various structures possessed by +many of the lower animals. Besides the claspers, the males of many rays +have clusters of strong sharp spines on their heads, and several rows along +"the upper outer surface of their pectoral fins." These are present in the +males of some species, which have other parts of their bodies smooth. They +are only temporarily developed during the breeding-season; and Dr. Gunther +suspects that they are brought into action as prehensile organs by the +doubling inwards and downwards of the two sides of the body. It is a +remarkable fact that the females and not the males of some species, as of +Raia clavata, have their backs studded with large hook-formed spines. (1. +Yarrell's 'Hist. of British Fishes,' vol. ii. 1836, pp 417, 425, 436. Dr. +Gunther informs me that the spines in R. clavata are peculiar to the +female.) + +The males alone of the capelin (Mallotus villosus, one of Salmonidae), are +provided with a ridge of closely-set, brush-like scales, by the aid of +which two males, one on each side, hold the female, whilst she runs with +great swiftness on the sandy beach, and there deposits her spawn. (2. The +'American Naturalist,' April 1871, p. 119.) The widely distinct +Monacanthus scopas presents a somewhat analogous structure. The male, as +Dr. Gunther informs me, has a cluster of stiff, straight spines, like those +of a comb, on the sides of the tail; and these in a specimen six inches +long were nearly one and a half inches in length; the female has in the +same place a cluster of bristles, which may be compared with those of a +tooth-brush. In another species, M. peronii, the male has a brush like +that possessed by the female of the last species, whilst the sides of the +tail in the female are smooth. In some other species of the same genus the +tail can be perceived to be a little roughened in the male and perfectly +smooth in the female; and lastly in others, both sexes have smooth sides. + +The males of many fish fight for the possession of the females. Thus the +male stickleback (Gasterosteus leiurus) has been described as "mad with +delight," when the female comes out of her hiding-place and surveys the +nest which he has made for her. "He darts round her in every direction, +then to his accumulated materials for the nest, then back again in an +instant; and as she does not advance he endeavours to push her with his +snout, and then tries to pull her by the tail and side-spine to the nest." +(3. See Mr. R. Warington's interesting articles in 'Annals and Magazine of +Natural History,' October 1852, and November 1855.) The males are said to +be polygamists (4. Noel Humphreys, 'River Gardens,' 1857.); they are +extraordinarily bold and pugnacious, whilst "the females are quite +pacific." Their battles are at times desperate; "for these puny combatants +fasten tight on each other for several seconds, tumbling over and over +again until their strength appears completely exhausted." With the rough- +tailed stickleback (G. trachurus) the males whilst fighting swim round and +round each other, biting and endeavouring to pierce each other with their +raised lateral spines. The same writer adds (5. Loudon's 'Magazine of +Natural History,' vol. iii. 1830, p. 331.), "the bite of these little +furies is very severe. They also use their lateral spines with such fatal +effect, that I have seen one during a battle absolutely rip his opponent +quite open, so that he sank to the bottom and died." When a fish is +conquered, "his gallant bearing forsakes him; his gay colours fade away; +and he hides his disgrace among his peaceable companions, but is for some +time the constant object of his conqueror's persecution." + +The male salmon is as pugnacious as the little stickleback; and so is the +male trout, as I hear from Dr. Gunther. Mr. Shaw saw a violent contest +between two male salmon which lasted the whole day; and Mr. R. Buist, +Superintendent of Fisheries, informs me that he has often watched from the +bridge at Perth the males driving away their rivals, whilst the females +were spawning. The males "are constantly fighting and tearing each other +on the spawning-beds, and many so injure each other as to cause the death +of numbers, many being seen swimming near the banks of the river in a state +of exhaustion, and apparently in a dying state." (6. The 'Field,' June +29, 1867. For Mr. Shaw's Statement, see 'Edinburgh Review,' 1843. Another +experienced observer (Scrope's 'Days of Salmon Fishing,' p. 60) remarks +that like the stag, the male would, if he could, keep all other males +away.) Mr. Buist informs me, that in June 1868, the keeper of the +Stormontfield breeding-ponds visited the northern Tyne and found about 300 +dead salmon, all of which with one exception were males; and he was +convinced that they had lost their lives by fighting. + +[Fig. 27. Head of male common salmon (Salmo salar) during the breeding- +season. +[This drawing, as well as all the others in the present chapter, have been +executed by the well-known artist, Mr. G. Ford, from specimens in the +British Museum, under the kind superintendence of Dr. Gunther.] + +Fig. 28. Head of female salmon.] + +The most curious point about the male salmon is that during the breeding- +season, besides a slight change in colour, "the lower jaw elongates, and a +cartilaginous projection turns upwards from the point, which, when the jaws +are closed, occupies a deep cavity between the intermaxillary bones of the +upper jaw." (7. Yarrell, 'History of British Fishes,' vol. ii. 1836, p. +10.) (Figs. 27 and 28.) In our salmon this change of structure lasts only +during the breeding-season; but in the Salmo lycaodon of N.W. America the +change, as Mr. J.K. Lord (8. 'The Naturalist in Vancouver's Island,' vol. +i. 1866, p. 54.) believes, is permanent, and best marked in the older males +which have previously ascended the rivers. In these old males the jaw +becomes developed into an immense hook-like projection, and the teeth grow +into regular fangs, often more than half an inch in length. With the +European salmon, according to Mr. Lloyd (9. 'Scandinavian Adventures,' +vol. i. 1854, pp. 100, 104.), the temporary hook-like structure serves to +strengthen and protect the jaws, when one male charges another with +wonderful violence; but the greatly developed teeth of the male American +salmon may be compared with the tusks of many male mammals, and they +indicate an offensive rather than a protective purpose. + +The salmon is not the only fish in which the teeth differ in the two sexes; +as this is the case with many rays. In the thornback (Raia clavata) the +adult male has sharp, pointed teeth, directed backwards, whilst those of +the female are broad and flat, and form a pavement; so that these teeth +differ in the two sexes of the same species more than is usual in distinct +genera of the same family. The teeth of the male become sharp only when he +is adult: whilst young they are broad and flat like those of the female. +As so frequently occurs with secondary sexual characters, both sexes of +some species of rays (for instance R. batis), when adult, possess sharp +pointed teeth; and here a character, proper to and primarily gained by the +male, appears to have been transmitted to the offspring of both sexes. The +teeth are likewise pointed in both sexes of R. maculata, but only when +quite adult; the males acquiring them at an earlier age than the females. +We shall hereafter meet with analogous cases in certain birds, in which the +male acquires the plumage common to both sexes when adult, at a somewhat +earlier age than does the female. With other species of rays the males +even when old never possess sharp teeth, and consequently the adults of +both sexes are provided with broad, flat teeth like those of the young, and +like those of the mature females of the above-mentioned species. (10. See +Yarrell's account of the rays in his 'History of British Fishes,' vol. ii. +1836, p. 416, with an excellent figure, and pp. 422, 432.) As the rays are +bold, strong and voracious fish, we may suspect that the males require +their sharp teeth for fighting with their rivals; but as they possess many +parts modified and adapted for the prehension of the female, it is possible +that their teeth may be used for this purpose. + +In regard to size, M. Carbonnier (11. As quoted in 'The Farmer,' 1868, p. +369.) maintains that the female of almost all fishes is larger than the +male; and Dr. Gunther does not know of a single instance in which the male +is actually larger than the female. With some Cyprinodonts the male is not +even half as large. As in many kinds of fishes the males habitually fight +together, it is surprising that they have not generally become larger and +stronger than the females through the effects of sexual selection. The +males suffer from their small size, for according to M. Carbonnier, they +are liable to be devoured by the females of their own species when +carnivorous, and no doubt by other species. Increased size must be in some +manner of more importance to the females, than strength and size are to the +males for fighting with other males; and this perhaps is to allow of the +production of a vast number of ova. + +[Fig. 29. Callionymus lyra. +Upper figure, male; +lower figure, female. +N.B. The lower figure is more reduced than the upper.] + +In many species the male alone is ornamented with bright colours; or these +are much brighter in the male than the female. The male, also, is +sometimes provided with appendages which appear to be of no more use to him +for the ordinary purposes of life, than are the tail feathers to the +peacock. I am indebted for most of the following facts to the kindness of +Dr. Gunther. There is reason to suspect that many tropical fishes differ +sexually in colour and structure; and there are some striking cases with +our British fishes. The male Callionymus lyra has been called the gemmeous +dragonet "from its brilliant gem-like colours." When fresh caught from the +sea the body is yellow of various shades, striped and spotted with vivid +blue on the head; the dorsal fins are pale brown with dark longitudinal +bands; the ventral, caudal, and anal fins being bluish-black. The female, +or sordid dragonet, was considered by Linnaeus, and by many subsequent +naturalists, as a distinct species; it is of a dingy reddish-brown, with +the dorsal fin brown and the other fins white. The sexes differ also in +the proportional size of the head and mouth, and in the position of the +eyes (12. I have drawn up this description from Yarrell's 'British +Fishes,' vol. i. 1836, pp. 261 and 266.); but the most striking difference +is the extraordinary elongation in the male (Fig. 29) of the dorsal fin. +Mr. W. Saville Kent remarks that this "singular appendage appears from my +observations of the species in confinement, to be subservient to the same +end as the wattles, crests, and other abnormal adjuncts of the male in +gallinaceous birds, for the purpose of fascinating their mates." (13. +'Nature,' July 1873, p. 264.) The young males resemble the adult females +in structure and colour. Throughout the genus Callionymus (14. 'Catalogue +of Acanth. Fishes in the British Museum,' by Dr. Gunther, 1861, pp. 138- +151.), the male is generally much more brightly spotted than the female, +and in several species, not only the dorsal, but the anal fin is much +elongated in the males. + +The male of the Cottus scorpius, or sea-scorpion, is slenderer and smaller +than the female. There is also a great difference in colour between them. +It is difficult, as Mr. Lloyd (15. 'Game Birds of Sweden,' etc., 1867, p. +466.) remarks, "for any one, who has not seen this fish during the +spawning-season, when its hues are brightest, to conceive the admixture of +brilliant colours with which it, in other respects so ill-favoured, is at +that time adorned." Both sexes of the Labrus mixtus, although very +different in colour, are beautiful; the male being orange with bright blue +stripes, and the female bright red with some black spots on the back. + +[Fig. 30. Xiphophorus Hellerii. +Upper figure, male; +lower figure, female.] + +In the very distinct family of the Cyprinodontidae--inhabitants of the +fresh waters of foreign lands--the sexes sometimes differ much in various +characters. In the male of the Mollienesia petenensis (16. With respect +to this and the following species I am indebted to Dr. Gunther for +information: see also his paper on the 'Fishes of Central America,' in +'Transact. Zoological Soc.' vol. vi. 1868, p. 485.), the dorsal fin is +greatly developed and is marked with a row of large, round, ocellated, +bright-coloured spots; whilst the same fin in the female is smaller, of a +different shape, and marked only with irregularly curved brown spots. In +the male the basal margin of the anal fin is also a little produced and +dark coloured. In the male of an allied form, the Xiphophorus Hellerii +(Fig. 30), the inferior margin of the caudal fin is developed into a long +filament, which, as I hear from Dr. Gunther, is striped with bright +colours. This filament does not contain any muscles, and apparently cannot +be of any direct use to the fish. As in the case of the Callionymus, the +males whilst young resemble the adult females in colour and structure. +Sexual differences such as these may be strictly compared with those which +are so frequent with gallinaceous birds. (17. Dr. Gunther makes this +remark; 'Catalogue of Fishes in the British Museum,' vol. iii. 1861, p. +141.) + +[Fig.31. Plecostomus barbatus. +Upper figure, head of male; +lower figure, female.] + +In a siluroid fish, inhabiting the fresh waters of South America, the +Plecostomus barbatus (18. See Dr. Gunther on this genus, in 'Proceedings +of the Zoological Society,' 1868, p. 232.) (Fig. 31), the male has its +mouth and inter-operculum fringed with a beard of stiff hairs, of which the +female shows hardly a trace. These hairs are of the nature of scales. In +another species of the same genus, soft flexible tentacles project from the +front part of the head of the male, which are absent in the female. These +tentacles are prolongations of the true skin, and therefore are not +homologous with the stiff hairs of the former species; but it can hardly be +doubted that both serve the same purpose. What this purpose may be, it is +difficult to conjecture; ornament does not here seem probable, but we can +hardly suppose that stiff hairs and flexible filaments can be useful in any +ordinary way to the males alone. In that strange monster, the Chimaera +monstrosa, the male has a hook-shaped bone on the top of the head, directed +forwards, with its end rounded and covered with sharp spines; in the female +"this crown is altogether absent," but what its use may be to the male is +utterly unknown. (19. F. Buckland, in 'Land and Water,' July 1868, p. +377, with a figure. Many other cases could be added of structures peculiar +to the male, of which the uses are not known.) + +The structures as yet referred to are permanent in the male after he has +arrived at maturity; but with some Blennies, and in another allied genus +(20. Dr. Gunther, 'Catalogue of Fishes,' vol. iii. pp. 221 and 240.), a +crest is developed on the head of the male only during the breeding-season, +and the body at the same time becomes more brightly-coloured. There can be +little doubt that this crest serves as a temporary sexual ornament, for the +female does not exhibit a trace of it. In other species of the same genus +both sexes possess a crest, and in at least one species neither sex is thus +provided. In many of the Chromidae, for instance in Geophagus and +especially in Cichla, the males, as I hear from Professor Agassiz (21. See +also 'A Journey in Brazil,' by Prof. and Mrs. Agassiz, 1868, p. 220.), have +a conspicuous protuberance on the forehead, which is wholly wanting in the +females and in the young males. Professor Agassiz adds, "I have often +observed these fishes at the time of spawning when the protuberance is +largest, and at other seasons when it is totally wanting, and the two sexes +shew no difference whatever in the outline of the profile of the head. I +never could ascertain that it subserves any special function, and the +Indians on the Amazon know nothing about its use." These protuberances +resemble, in their periodical appearance, the fleshy carbuncles on the +heads of certain birds; but whether they serve as ornaments must remain at +present doubtful. + +I hear from Professor Agassiz and Dr. Gunther, that the males of those +fishes, which differ permanently in colour from the females, often become +more brilliant during the breeding-season. This is likewise the case with +a multitude of fishes, the sexes of which are identical in colour at all +other seasons of the year. The tench, roach, and perch may be given as +instances. The male salmon at this season is "marked on the cheeks with +orange-coloured stripes, which give it the appearance of a Labrus, and the +body partakes of a golden orange tinge. The females are dark in colour, +and are commonly called black-fish." (22. Yarrell, 'History of British +Fishes,' vol. ii. 1836, pp. 10, 12, 35.) An analogous and even greater +change takes place with the Salmo eriox or bull trout; the males of the +char (S. umbla) are likewise at this season rather brighter in colour than +the females. (23. W. Thompson, in 'Annals and Magazine of Natural +History,' vol. vi. 1841, p. 440.) The colours of the pike (Esox +reticulatus) of the United States, especially of the male, become, during +the breeding-season, exceedingly intense, brilliant, and iridescent. (24. +'The American Agriculturalist,' 1868, p. 100.) Another striking instance +out of many is afforded by the male stickleback (Gasterosteus leiurus), +which is described by Mr. Warington (25. 'Annals and Mag. of Nat. Hist.' +Oct. 1852.), as being then "beautiful beyond description." The back and +eyes of the female are simply brown, and the belly white. The eyes of the +male, on the other hand, are "of the most splendid green, having a metallic +lustre like the green feathers of some humming-birds. The throat and belly +are of a bright crimson, the back of an ashy-green, and the whole fish +appears as though it were somewhat translucent and glowed with an internal +incandescence." After the breeding season these colours all change, the +throat and belly become of a paler red, the back more green, and the +glowing tints subside. + +With respect to the courtship of fishes, other cases have been observed +since the first edition of this book appeared, besides that already given +of the stickleback. Mr. W.S. Kent says that the male of the Labrus mixtus, +which, as we have seen, differs in colour from the female, makes "a deep +hollow in the sand of the tank, and then endeavours in the most persuasive +manner to induce a female of the same species to share it with him, +swimming backwards and forwards between her and the completed nest, and +plainly exhibiting the greatest anxiety for her to follow." The males of +Cantharus lineatus become, during the breeding-season, of deep leaden- +black; they then retire from the shoal, and excavate a hollow as a nest. +"Each male now mounts vigilant guard over his respective hollow, and +vigorously attacks and drives away any other fish of the same sex. Towards +his companions of the opposite sex his conduct is far different; many of +the latter are now distended with spawn, and these he endeavours by all the +means in his power to lure singly to his prepared hollow, and there to +deposit the myriad ova with which they are laden, which he then protects +and guards with the greatest care." (26. 'Nature,' May 1873, p. 25.) + +A more striking case of courtship, as well as of display, by the males of a +Chinese Macropus has been given by M. Carbonnier, who carefully observed +these fishes under confinement. (27. 'Bulletin de la Societé d'Acclimat.' +Paris, July 1869, and Jan. 1870.) The males are most beautifully coloured, +more so than the females. During the breeding-season they contend for the +possession of the females; and, in the act of courtship, expand their fins, +which are spotted and ornamented with brightly coloured rays, in the same +manner, according to M. Carbonnier, as the peacock. They then also bound +about the females with much vivacity, and appear by "l'etalage de leurs +vives couleurs chercher a attirer l'attention des femelles, lesquelles ne +paraissaient indifferentes a ce manege, elles nageaient avec une molle +lenteur vers les males et semblaient se complaire dans leur voisinage." +After the male has won his bride, he makes a little disc of froth by +blowing air and mucus out of his mouth. He then collects the fertilised +ova, dropped by the female, in his mouth; and this caused M. Carbonnier +much alarm, as he thought that they were going to be devoured. But the +male soon deposits them in the disc of froth, afterwards guarding them, +repairing the froth, and taking care of the young when hatched. I mention +these particulars because, as we shall presently see, there are fishes, the +males of which hatch their eggs in their mouths; and those who do not +believe in the principle of gradual evolution might ask how could such a +habit have originated; but the difficulty is much diminished when we know +that there are fishes which thus collect and carry the eggs; for if delayed +by any cause in depositing them, the habit of hatching them in their mouths +might have been acquired. + +To return to our more immediate subject. The case stands thus: female +fishes, as far as I can learn, never willingly spawn except in the presence +of the males; and the males never fertilise the ova except in the presence +of the females. The males fight for the possession of the females. In +many species, the males whilst young resemble the females in colour; but +when adult become much more brilliant, and retain their colours throughout +life. In other species the males become brighter than the females and +otherwise more highly ornamented, only during the season of love. The +males sedulously court the females, and in one case, as we have seen, take +pains in displaying their beauty before them. Can it be believed that they +would thus act to no purpose during their courtship? And this would be the +case, unless the females exert some choice and select those males which +please or excite them most. If the female exerts such choice, all the +above facts on the ornamentation of the males become at once intelligible +by the aid of sexual selection. + +We have next to inquire whether this view of the bright colours of certain +male fishes having been acquired through sexual selection can, through the +law of the equal transmission of characters to both sexes, be extended to +those groups in which the males and females are brilliant in the same, or +nearly the same degree and manner. In such a genus as Labrus, which +includes some of the most splendid fishes in the world--for instance, the +Peacock Labrus (L. pavo), described (28. Bory Saint Vincent, in 'Dict. +Class. d'Hist. Nat.' tom. ix. 1826, p. 151.), with pardonable exaggeration, +as formed of polished scales of gold, encrusting lapis-lazuli, rubies, +sapphires, emeralds, and amethysts--we may, with much probability, accept +this belief; for we have seen that the sexes in at least one species of the +genus differ greatly in colour. With some fishes, as with many of the +lowest animals, splendid colours may be the direct result of the nature of +their tissues and of the surrounding conditions, without the aid of +selection of any kind. The gold-fish (Cyprinus auratus), judging from the +analogy of the golden variety of the common carp, is perhaps a case in +point, as it may owe its splendid colours to a single abrupt variation, due +to the conditions to which this fish has been subjected under confinement. +It is, however, more probable that these colours have been intensified +through artificial selection, as this species has been carefully bred in +China from a remote period. (29. Owing to some remarks on this subject, +made in my work 'On the Variation of Animals under Domestication,' Mr. W.F. +Mayers ('Chinese Notes and Queries,' Aug. 1868, p. 123) has searched the +ancient Chinese encyclopedias. He finds that gold-fish were first reared +in confinement during the Sung Dynasty, which commenced A.D. 960. In the +year 1129 these fishes abounded. In another place it is said that since +the year 1548 there has been "produced at Hangchow a variety called the +fire-fish, from its intensely red colour. It is universally admired, and +there is not a household where it is not cultivated, IN RIVALRY AS TO ITS +COLOUR, and as a source of profit.") Under natural conditions it does not +seem probable that beings so highly organised as fishes, and which live +under such complex relations, should become brilliantly coloured without +suffering some evil or receiving some benefit from so great a change, and +consequently without the intervention of natural selection. + +What, then, are we to conclude in regard to the many fishes, both sexes of +which are splendidly coloured? Mr. Wallace (30. 'Westminster Review,' +July 1867, p. 7.) believes that the species which frequent reefs, where +corals and other brightly-coloured organisms abound, are brightly coloured +in order to escape detection by their enemies; but according to my +recollection they were thus rendered highly conspicuous. In the fresh- +waters of the tropics there are no brilliantly-coloured corals or other +organisms for the fishes to resemble; yet many species in the Amazons are +beautifully coloured, and many of the carnivorous Cyprinidae in India are +ornamented with "bright longitudinal lines of various tints." (31. +'Indian Cyprinidae,' by Mr. M'Clelland, 'Asiatic Researches,' vol. xix. +part ii. 1839, p. 230.) Mr. M'Clelland, in describing these fishes, goes +so far as to suppose that "the peculiar brilliancy of their colours" serves +as "a better mark for king-fishers, terns, and other birds which are +destined to keep the number of these fishes in check"; but at the present +day few naturalists will admit that any animal has been made conspicuous as +an aid to its own destruction. It is possible that certain fishes may have +been rendered conspicuous in order to warn birds and beasts of prey that +they were unpalatable, as explained when treating of caterpillars; but it +is not, I believe, known that any fish, at least any fresh-water fish, is +rejected from being distasteful to fish-devouring animals. On the whole, +the most probable view in regard to the fishes, of which both sexes are +brilliantly coloured, is that their colours were acquired by the males as a +sexual ornament, and were transferred equally, or nearly so, to the other +sex. + +We have now to consider whether, when the male differs in a marked manner +from the female in colour or in other ornaments, he alone has been +modified, the variations being inherited by his male offspring alone; or +whether the female has been specially modified and rendered inconspicuous +for the sake of protection, such modifications being inherited only by the +females. It is impossible to doubt that colour has been gained by many +fishes as a protection: no one can examine the speckled upper surface of a +flounder, and overlook its resemblance to the sandy bed of the sea on which +it lives. Certain fishes, moreover, can through the action of the nervous +system change their colours in adaptation to surrounding objects, and that +within a short time. (32. G. Pouchet, 'L'Institut.' Nov. 1, 1871, p. +134.) One of the most striking instances ever recorded of an animal being +protected by its colour (as far as it can be judged of in preserved +specimens), as well as by its form, is that given by Dr. Gunther (33. +'Proc. Zoolog. Soc.' 1865, p. 327, pl. xiv. and xv.) of a pipe-fish, which, +with its reddish streaming filaments, is hardly distinguishable from the +sea-weed to which it clings with its prehensile tail. But the question now +under consideration is whether the females alone have been modified for +this object. We can see that one sex will not be modified through natural +selection for the sake of protection more than the other, supposing both to +vary, unless one sex is exposed for a longer period to danger, or has less +power of escaping from such danger than the other; and it does not appear +that with fishes the sexes differ in these respects. As far as there is +any difference, the males, from being generally smaller and from wandering +more about, are exposed to greater danger than the females; and yet, when +the sexes differ, the males are almost always the more conspicuously +coloured. The ova are fertilised immediately after being deposited; and +when this process lasts for several days, as in the case of the salmon (34. +Yarrell, 'British Fishes,' vol. ii. p. 11.), the female, during the whole +time, is attended by the male. After the ova are fertilised they are, in +most cases, left unprotected by both parents, so that the males and +females, as far as oviposition is concerned, are equally exposed to danger, +and both are equally important for the production of fertile ova; +consequently the more or less brightly-coloured individuals of either sex +would be equally liable to be destroyed or preserved, and both would have +an equal influence on the colours of their offspring. + +Certain fishes, belonging to several families, make nests, and some of them +take care of their young when hatched. Both sexes of the bright coloured +Crenilabrus massa and melops work together in building their nests with +sea-weed, shells, etc. (35. According to the observations of M. Gerbe; +see Gunther's 'Record of Zoolog. Literature,' 1865, p. 194.) But the males +of certain fishes do all the work, and afterwards take exclusive charge of +the young. This is the case with the dull-coloured gobies (36. Cuvier, +'Regne Animal,' vol. ii. 1829, p. 242.), in which the sexes are not known +to differ in colour, and likewise with the sticklebacks (Gasterosteus), in +which the males become brilliantly coloured during the spawning season. +The male of the smooth-tailed stickleback (G. leiurus) performs the duties +of a nurse with exemplary care and vigilance during a long time, and is +continually employed in gently leading back the young to the nest, when +they stray too far. He courageously drives away all enemies including the +females of his own species. It would indeed be no small relief to the +male, if the female, after depositing her eggs, were immediately devoured +by some enemy, for he is forced incessantly to drive her from the nest. +(37. See Mr. Warington's most interesting description of the habits of the +Gasterosteus leiurus in 'Annals and Magazine of Nat. History,' November +1855.) + +The males of certain other fishes inhabiting South America and Ceylon, +belonging to two distinct Orders, have the extraordinary habit of hatching +within their mouths, or branchial cavities, the eggs laid by the females. +(38. Prof. Wyman, in 'Proc. Boston Soc. of Nat. Hist.' Sept. 15, 1857. +Also Prof. Turner, in 'Journal of Anatomy and Physiology,' Nov. 1, 1866, p. +78. Dr. Gunther has likewise described other cases.) I am informed by +Professor Agassiz that the males of the Amazonian species which follow this +habit, "not only are generally brighter than the females, but the +difference is greater at the spawning-season than at any other time." The +species of Geophagus act in the same manner; and in this genus, a +conspicuous protuberance becomes developed on the forehead of the males +during the breeding-season. With the various species of Chromids, as +Professor Agassiz likewise informs me, sexual differences in colour may be +observed, "whether they lay their eggs in the water among aquatic plants, +or deposit them in holes, leaving them to come out without further care, or +build shallow nests in the river mud, over which they sit, as our Pomotis +does. It ought also to be observed that these sitters are among the +brightest species in their respective families; for instance, Hygrogonus is +bright green, with large black ocelli, encircled with the most brilliant +red." Whether with all the species of Chromids it is the male alone which +sits on the eggs is not known. It is, however, manifest that the fact of +the eggs being protected or unprotected by the parents, has had little or +no influence on the differences in colour between the sexes. It is further +manifest, in all the cases in which the males take exclusive charge of the +nests and young, that the destruction of the brighter-coloured males would +be far more influential on the character of the race, than the destruction +of the brighter-coloured females; for the death of the male during the +period of incubation or nursing would entail the death of the young, so +that they could not inherit his peculiarities; yet, in many of these very +cases the males are more conspicuously coloured than the females. + +In most of the Lophobranchii (Pipe-fish, Hippocampi, etc.) the males have +either marsupial sacks or hemispherical depressions on the abdomen, in +which the ova laid by the female are hatched. The males also shew great +attachment to their young. (39. Yarrell, 'History of British Fishes,' +vol. ii. 1836, pp. 329, 338.) The sexes do not commonly differ much in +colour; but Dr. Gunther believes that the male Hippocampi are rather +brighter than the females. The genus Solenostoma, however, offers a +curious exceptional case (40. Dr. Gunther, since publishing an account of +this species in 'The Fishes of Zanzibar,' by Col. Playfair, 1866, p. 137, +has re-examined the specimens, and has given me the above information.), +for the female is much more vividly-coloured and spotted than the male, and +she alone has a marsupial sack and hatches the eggs; so that the female of +Solenostoma differs from all the other Lophobranchii in this latter +respect, and from almost all other fishes, in being more brightly-coloured +than the male. It is improbable that this remarkable double inversion of +character in the female should be an accidental coincidence. As the males +of several fishes, which take exclusive charge of the eggs and young, are +more brightly coloured than the females, and as here the female Solenostoma +takes the same charge and is brighter than the male, it might be argued +that the conspicuous colours of that sex which is the more important of the +two for the welfare of the offspring, must be in some manner protective. +But from the large number of fishes, of which the males are either +permanently or periodically brighter than the females, but whose life is +not at all more important for the welfare of the species than that of the +female, this view can hardly be maintained. When we treat of birds we +shall meet with analogous cases, where there has been a complete inversion +of the usual attributes of the two sexes, and we shall then give what +appears to be the probable explanation, namely, that the males have +selected the more attractive females, instead of the latter having +selected, in accordance with the usual rule throughout the animal kingdom, +the more attractive males. + +On the whole we may conclude, that with most fishes, in which the sexes +differ in colour or in other ornamental characters, the males originally +varied, with their variations transmitted to the same sex, and accumulated +through sexual selection by attracting or exciting the females. In many +cases, however, such characters have been transferred, either partially or +completely, to the females. In other cases, again, both sexes have been +coloured alike for the sake of protection; but in no instance does it +appear that the female alone has had her colours or other characters +specially modified for this latter purpose. + +The last point which need be noticed is that fishes are known to make +various noises, some of which are described as being musical. Dr. Dufosse, +who has especially attended to this subject, says that the sounds are +voluntarily produced in several ways by different fishes: by the friction +of the pharyngeal bones--by the vibration of certain muscles attached to +the swim bladder, which serves as a resounding board--and by the vibration +of the intrinsic muscles of the swim bladder. By this latter means the +Trigla produces pure and long-drawn sounds which range over nearly an +octave. But the most interesting case for us is that of two species of +Ophidium, in which the males alone are provided with a sound-producing +apparatus, consisting of small movable bones, with proper muscles, in +connection with the swim bladder. (41. 'Comptes-Rendus,' tom. xlvi. 1858, +p. 353; tom. xlvii. 1858, p. 916; tom. liv. 1862, p. 393. The noise made +by the Umbrinas (Sciaena aquila), is said by some authors to be more like +that of a flute or organ, than drumming: Dr. Zouteveen, in the Dutch +translation of this work (vol. ii. p. 36), gives some further particulars +on the sounds made by fishes.) The drumming of the Umbrinas in the +European seas is said to be audible from a depth of twenty fathoms; and the +fishermen of Rochelle assert "that the males alone make the noise during +the spawning-time; and that it is possible by imitating it, to take them +without bait." (42. The Rev. C. Kingsley, in 'Nature,' May 1870, p. 40.) +From this statement, and more especially from the case of Ophidium, it is +almost certain that in this, the lowest class of the Vertebrata, as with so +many insects and spiders, sound-producing instruments have, at least in +some cases, been developed through sexual selection, as a means for +bringing the sexes together. + +AMPHIBIANS. + +URODELA. + +[Fig. 32. Triton cristatus (half natural size, from Bell's 'British +Reptiles'). +Upper figure, male during the breeding season; +lower figure, female.] + +I will begin with the tailed amphibians. The sexes of salamanders or newts +often differ much both in colour and structure. In some species prehensile +claws are developed on the fore-legs of the males during the breeding- +season: and at this season in the male Triton palmipes the hind-feet are +provided with a swimming-web, which is almost completely absorbed during +the winter; so that their feet then resemble those of the female. (43. +Bell, 'History of British Reptiles,' 2nd ed., 1849, pp. 156-159.) This +structure no doubt aids the male in his eager search and pursuit of the +female. Whilst courting her he rapidly vibrates the end of his tail. With +our common newts (Triton punctatus and cristatus) a deep, much indented +crest is developed along the back and tail of the male during the breeding- +season, which disappears during the winter. Mr. St. George Mivart informs +me that it is not furnished with muscles, and therefore cannot be used for +locomotion. As during the season of courtship it becomes edged with bright +colours, there can hardly be a doubt that it is a masculine ornament. In +many species the body presents strongly contrasted, though lurid tints, and +these become more vivid during the breeding-season. The male, for +instance, of our common little newt (Triton punctatus) is "brownish-grey +above, passing into yellow beneath, which in the spring becomes a rich +bright orange, marked everywhere with round dark spots." The edge of the +crest also is then tipped with bright red or violet. The female is usually +of a yellowish-brown colour with scattered brown dots, and the lower +surface is often quite plain. (44. Bell, 'History of British Reptiles,' +2nd ed., 1849, pp. 146, 151.) The young are obscurely tinted. The ova are +fertilised during the act of deposition, and are not subsequently tended by +either parent. We may therefore conclude that the males have acquired +their strongly-marked colours and ornamental appendages through sexual +selection; these being transmitted either to the male offspring alone, or +to both sexes. + +ANURA OR BATRACHIA. + +With many frogs and toads the colours evidently serve as a protection, such +as the bright green tints of tree frogs and the obscure mottled shades of +many terrestrial species. The most conspicuously-coloured toad which I +ever saw, the Phryniscus nigricans (45. 'Zoology of the Voyage of the +"Beagle,"' 1843. Bell, ibid. p. 49.), had the whole upper surface of the +body as black as ink, with the soles of the feet and parts of the abdomen +spotted with the brightest vermilion. It crawled about the bare sandy or +open grassy plains of La Plata under a scorching sun, and could not fail to +catch the eye of every passing creature. These colours are probably +beneficial by making this animal known to all birds of prey as a nauseous +mouthful. + +In Nicaragua there is a little frog "dressed in a bright livery of red and +blue" which does not conceal itself like most other species, but hops about +during the daytime, and Mr. Belt says (46. 'The Naturalist in Nicaragua,' +1874, p. 321.) that as soon as he saw its happy sense of security, he felt +sure that it was uneatable. After several trials he succeeded in tempting +a young duck to snatch up a young one, but it was instantly rejected; and +the duck "went about jerking its head, as if trying to throw off some +unpleasant taste." + +With respect to sexual differences of colour, Dr. Gunther does not know of +any striking instance either with frogs or toads; yet he can often +distinguish the male from the female by the tints of the former being a +little more intense. Nor does he know of any striking difference in +external structure between the sexes, excepting the prominences which +become developed during the breeding-season on the front legs of the male, +by which he is enabled to hold the female. (47. The male alone of the +Bufo sikimmensis (Dr. Anderson, 'Proc. Zoolog. Soc.' 1871, p. 204) has two +plate-like callosities on the thorax and certain rugosities on the fingers, +which perhaps subserve the same end as the above-mentioned prominences.) +It is surprising that these animals have not acquired more strongly-marked +sexual characters; for though cold-blooded their passions are strong. Dr. +Gunther informs me that he has several times found an unfortunate female +toad dead and smothered from having been so closely embraced by three or +four males. Frogs have been observed by Professor Hoffman in Giessen +fighting all day long during the breeding-season, and with so much violence +that one had its body ripped open. + +Frogs and toads offer one interesting sexual difference, namely, in the +musical powers possessed by the males; but to speak of music, when applied +to the discordant and overwhelming sounds emitted by male bull-frogs and +some other species, seems, according to our taste, a singularly +inappropriate expression. Nevertheless, certain frogs sing in a decidedly +pleasing manner. Near Rio Janeiro I used often to sit in the evening to +listen to a number of little Hylae, perched on blades of grass close to the +water, which sent forth sweet chirping notes in harmony. The various +sounds are emitted chiefly by the males during the breeding-season, as in +the case of the croaking of our common frog. (48. Bell, 'History British +Reptiles,' 1849, p. 93.) In accordance with this fact the vocal organs of +the males are more highly-developed than those of the females. In some +genera the males alone are provided with sacs which open into the larynx. +(49. J. Bishop, in 'Todd's Cyclopaedia of Anatomy and Physiology,' vol. +iv. p. 1503.) For instance, in the edible frog (Rana esculenta) "the sacs +are peculiar to the males, and become, when filled with air in the act of +croaking, large globular bladders, standing out one on each side of the +head, near the corners of the mouth." The croak of the male is thus +rendered exceedingly powerful; whilst that of the female is only a slight +groaning noise. (50. Bell, ibid. pp. 112-114.) In the several genera of +the family the vocal organs differ considerably in structure, and their +development in all cases may be attributed to sexual selection. + +REPTILES. + +CHELONIA. + +Tortoises and turtles do not offer well-marked sexual differences. In some +species, the tail of the male is longer than that of the female. In some, +the plastron or lower surface of the shell of the male is slightly concave +in relation to the back of the female. The male of the mud-turtle of the +United States (Chrysemys picta) has claws on its front feet twice as long +as those of the female; and these are used when the sexes unite. (51. Mr. +C.J. Maynard, 'The American Naturalist,' Dec. 1869, p. 555.) With the huge +tortoise of the Galapagos Islands (Testudo nigra) the males are said to +grow to a larger size than the females: during the pairing-season, and at +no other time, the male utters a hoarse bellowing noise, which can be heard +at the distance of more than a hundred yards; the female, on the other +hand, never uses her voice. (52. See my 'Journal of Researches during the +Voyage of the "Beagle,"' 1845, p. 384.) + +With the Testudo elegans of India, it is said "that the combats of the +males may be heard at some distance, from the noise they produce in butting +against each other." (53. Dr. Gunther, 'Reptiles of British India,' 1864, +p. 7.) + +CROCODILIA. + +The sexes apparently do not differ in colour; nor do I know that the males +fight together, though this is probable, for some kinds make a prodigious +display before the females. Bartram (54. 'Travels through Carolina,' +etc., 1791, p. 128.) describes the male alligator as striving to win the +female by splashing and roaring in the midst of a lagoon, "swollen to an +extent ready to burst, with its head and tail lifted up, he springs or +twirls round on the surface of the water, like an Indian chief rehearsing +his feats of war." During the season of love, a musky odour is emitted by +the submaxiliary glands of the crocodile, and pervades their haunts. (55. +Owen, 'Anatomy of Vertebrates,' vol. i. 1866, p. 615.) + +OPHIDIA. + +Dr. Gunther informs me that the males are always smaller than the females, +and generally have longer and slenderer tails; but he knows of no other +difference in external structure. In regard to colour, be can almost +always distinguish the male from the female, by his more strongly- +pronounced tints; thus the black zigzag band on the back of the male +English viper is more distinctly defined than in the female. The +difference is much plainer in the rattle-snakes of N. America, the male of +which, as the keeper in the Zoological Gardens shewed me, can at once be +distinguished from the female by having more lurid yellow about its whole +body. In S. Africa the Bucephalus capensis presents an analogous +difference, for the female "is never so fully variegated with yellow on the +sides as the male." (56. Sir Andrew Smith, 'Zoology of S. Africa: +Reptilia,' 1849, pl. x.) The male of the Indian Dipsas cynodon, on the +other hand, is blackish-brown, with the belly partly black, whilst the +female is reddish or yellowish-olive, with the belly either uniform +yellowish or marbled with black. In the Tragops dispar of the same country +the male is bright green, and the female bronze-coloured. (57. Dr. A. +Gunther, 'Reptiles of British India,' Ray Soc., 1864, pp. 304, 308.) No +doubt the colours of some snakes are protective, as shewn by the green +tints of tree-snakes, and the various mottled shades of the species which +live in sandy places; but it is doubtful whether the colours of many kinds, +for instance of the common English snake and viper, serve to conceal them; +and this is still more doubtful with the many foreign species which are +coloured with extreme elegance. The colours of certain species are very +different in the adult and young states. (58. Dr. Stoliczka, 'Journal of +Asiatic Society of Bengal,' vol. xxxix, 1870, pp. 205, 211.) + +During the breeding-season the anal scent-glands of snakes are in active +function (59. Owen, 'Anatomy of Vertebrates,' vol. i. 1866, p. 615.); and +so it is with the same glands in lizards, and as we have seen with the +submaxiliary glands of crocodiles. As the males of most animals search for +the females, these odoriferous glands probably serve to excite or charm the +female, rather than to guide her to the spot where the male may be found. +Male snakes, though appearing so sluggish, are amorous; for many have been +observed crowding round the same female, and even round her dead body. +They are not known to fight together from rivalry. Their intellectual +powers are higher than might have been anticipated. In the Zoological +Gardens they soon learn not to strike at the iron bar with which their +cages are cleaned; and Dr. Keen of Philadelphia informs me that some snakes +which he kept learned after four or five times to avoid a noose, with which +they were at first easily caught. An excellent observer in Ceylon, Mr. E. +Layard, saw (60. 'Rambles in Ceylon,' in 'Annals and Magazine of Natural +History,' 2nd series, vol. ix. 1852, p. 333.) a cobra thrust its head +through a narrow hole and swallow a toad. "With this encumbrance he could +not withdraw himself; finding this, he reluctantly disgorged the precious +morsel, which began to move off; this was too much for snake philosophy to +bear, and the toad was again seized, and again was the snake, after violent +efforts to escape, compelled to part with its prey. This time, however, a +lesson had been learnt, and the toad was seized by one leg, withdrawn, and +then swallowed in triumph." + +The keeper in the Zoological Gardens is positive that certain snakes, for +instance Crotalus and Python, distinguish him from all other persons. +Cobras kept together in the same cage apparently feel some attachment +towards each other. (61. Dr. Gunther, 'Reptiles of British India,' 1864, +p. 340.) + +It does not, however, follow because snakes have some reasoning power, +strong passions and mutual affection, that they should likewise be endowed +with sufficient taste to admire brilliant colours in their partners, so as +to lead to the adornment of the species through sexual selection. +Nevertheless, it is difficult to account in any other manner for the +extreme beauty of certain species; for instance, of the coral-snakes of S. +America, which are of a rich red with black and yellow transverse bands. I +well remember how much surprise I felt at the beauty of the first coral- +snake which I saw gliding across a path in Brazil. Snakes coloured in this +peculiar manner, as Mr. Wallace states on the authority of Dr. Gunther (62. +'Westminster Review,' July 1st, 1867, p. 32.), are found nowhere else in +the world except in S. America, and here no less than four genera occur. +One of these, Elaps, is venomous; a second and widely-distinct genus is +doubtfully venomous, and the two others are quite harmless. The species +belonging to these distinct genera inhabit the same districts, and are so +like each other that no one "but a naturalist would distinguish the +harmless from the poisonous kinds." Hence, as Mr. Wallace believes, the +innocuous kinds have probably acquired their colours as a protection, on +the principle of imitation; for they would naturally be thought dangerous +by their enemies. The cause, however, of the bright colours of the +venomous Elaps remains to be explained, and this may perhaps be sexual +selection. + +Snakes produce other sounds besides hissing. The deadly Echis carinata has +on its sides some oblique rows of scales of a peculiar structure with +serrated edges; and when this snake is excited these scales are rubbed +against each other, which produces "a curious prolonged, almost hissing +sound." (63. Dr. Anderson, 'Proc. Zoolog. Soc.' 1871, p. 196.) With +respect to the rattling of the rattle-snake, we have at last some definite +information: for Professor Aughey states (64. The 'American Naturalist,' +1873, p. 85.), that on two occasions, being himself unseen, he watched from +a little distance a rattle-snake coiled up with head erect, which continued +to rattle at short intervals for half an hour: and at last he saw another +snake approach, and when they met they paired. Hence he is satisfied that +one of the uses of the rattle is to bring the sexes together. +Unfortunately he did not ascertain whether it was the male or the female +which remained stationary and called for the other. But it by no means +follows from the above fact that the rattle may not be of use to these +snakes in other ways, as a warning to animals which would otherwise attack +them. Nor can I quite disbelieve the several accounts which have appeared +of their thus paralysing their prey with fear. Some other snakes also make +a distinct noise by rapidly vibrating their tails against the surrounding +stalks of plants; and I have myself heard this in the case of a +Trigonocephalus in S. America. + +LACERTILIA. + +The males of some, probably of many kinds of lizards, fight together from +rivalry. Thus the arboreal Anolis cristatellus of S. America is extremely +pugnacious: "During the spring and early part of the summer, two adult +males rarely meet without a contest. On first seeing one another, they nod +their heads up and down three or four times, and at the same time expanding +the frill or pouch beneath the throat; their eyes glisten with rage, and +after waving their tails from side to side for a few seconds, as if to +gather energy, they dart at each other furiously, rolling over and over, +and holding firmly with their teeth. The conflict generally ends in one of +the combatants losing his tail, which is often devoured by the victor." +The male of this species is considerably larger than the female (65. Mr. +N.L. Austen kept these animals alive for a considerable time; see 'Land and +Water,' July 1867, p. 9.); and this, as far as Dr. Gunther has been able to +ascertain, is the general rule with lizards of all kinds. The male alone +of the Cyrtodactylus rubidus of the Andaman Islands possesses pre-anal +pores; and these pores, judging from analogy, probably serve to emit an +odour. (66. Stoliczka, 'Journal of the Asiatic Society of Bengal,' vol. +xxxiv. 1870, p. 166.) + +[Fig.33. Sitana minor. +Male with the gular pouch expanded (from Gunther's 'Reptiles of India')'] + +The sexes often differ greatly in various external characters. The male of +the above-mentioned Anolis is furnished with a crest which runs along the +back and tail, and can be erected at pleasure; but of this crest the female +does not exhibit a trace. In the Indian Cophotis ceylanica, the female has +a dorsal crest, though much less developed than in the male; and so it is, +as Dr. Gunther informs me, with the females of many Iguanas, Chameleons, +and other lizards. In some species, however, the crest is equally +developed in both sexes, as in the Iguana tuberculata. In the genus +Sitana, the males alone are furnished with a large throat pouch (Fig. 33), +which can be folded up like a fan, and is coloured blue, black, and red; +but these splendid colours are exhibited only during the pairing-season. +The female does not possess even a rudiment of this appendage. In the +Anolis cristatellus, according to Mr. Austen, the throat pouch, which is +bright red marbled with yellow, is present in the female, though in a +rudimental condition. Again, in certain other lizards, both sexes are +equally well provided with throat pouches. Here we see with species +belonging to the same group, as in so many previous cases, the same +character either confined to the males, or more largely developed in them +than in the females, or again equally developed in both sexes. The little +lizards of the genus Draco, which glide through the air on their rib- +supported parachutes, and which in the beauty of their colours baffle +description, are furnished with skinny appendages to the throat "like the +wattles of gallinaceous birds." These become erected when the animal is +excited. They occur in both sexes, but are best developed when the male +arrives at maturity, at which age the middle appendage is sometimes twice +as long as the head. Most of the species likewise have a low crest running +along the neck; and this is much more developed in the full-grown males +than in the females or young males. (67. All the foregoing statements and +quotations, in regard to Cophotis, Sitana and Draco, as well as the +following facts in regard to Ceratophora and Chamaeleon, are from Dr. +Gunther himself, or from his magnificent work on the 'Reptiles of British +India,' Ray Soc., 1864, pp. 122, 130, 135.) + +A Chinese species is said to live in pairs during the spring; "and if one +is caught, the other falls from the tree to the ground, and allows itself +to be captured with impunity"--I presume from despair. (68. Mr. Swinhoe, +'Proc. Zoolog. Soc.' 1870, p. 240.) + +[Fig. 34. Ceratophora Stoddartii. +Upper figure; +lower figure, female.] + +There are other and much more remarkable differences between the sexes of +certain lizards. The male of Ceratophora aspera bears on the extremity of +his snout an appendage half as long as the head. It is cylindrical, +covered with scales, flexible, and apparently capable of erection: in the +female it is quite rudimental. In a second species of the same genus a +terminal scale forms a minute horn on the summit of the flexible appendage; +and in a third species (C. Stoddartii, fig. 34) the whole appendage is +converted into a horn, which is usually of a white colour, but assumes a +purplish tint when the animal is excited. In the adult male of this latter +species the horn is half an inch in length, but it is of quite minute size +in the female and in the young. These appendages, as Dr. Gunther has +remarked to me, may be compared with the combs of gallinaceous birds, and +apparently serve as ornaments. + +[Fig. 35. Chamaeleo bifurcus. +Upper figure, male; +lower figure, female. + +Fig. 36. Chamaeleo Owenii. +Upper figure, male; +lower figure, female.] + +In the genus Chamaeleon we come to the acme of difference between the +sexes. The upper part of the skull of the male C. bifurcus (Fig. 35), an +inhabitant of Madagascar, is produced into two great, solid, bony +projections, covered with scales like the rest of the head; and of this +wonderful modification of structure the female exhibits only a rudiment. +Again, in Chamaeleo Owenii (Fig. 36), from the West Coast of Africa, the +male bears on his snout and forehead three curious horns, of which the +female has not a trace. These horns consist of an excrescence of bone +covered with a smooth sheath, forming part of the general integuments of +the body, so that they are identical in structure with those of a bull, +goat, or other sheath-horned ruminant. Although the three horns differ so +much in appearance from the two great prolongations of the skull in C. +bifurcus, we can hardly doubt that they serve the same general purpose in +the economy of these two animals. The first conjecture, which will occur +to every one, is that they are used by the males for fighting together; and +as these animals are very quarrelsome (69. Dr. Buchholz, 'Monatsbericht K. +Preuss. Akad.' Jan. 1874, p. 78.), this is probably a correct view. Mr. +T.W. Wood also informs me that he once watched two individuals of C. +pumilus fighting violently on the branch of a tree; they flung their heads +about and tried to bite each other; they then rested for a time and +afterwards continued their battle. + +With many lizards the sexes differ slightly in colour, the tints and +stripes of the males being brighter and more distinctly defined than in the +females. This, for instance, is the case with the above Cophotis and with +the Acanthodactylus capensis of S. Africa. In a Cordylus of the latter +country, the male is either much redder or greener than the female. In the +Indian Calotes nigrilabris there is a still greater difference; the lips +also of the male are black, whilst those of the female are green. In our +common little viviparous lizard (Zootoca vivipara) "the under side of the +body and base of the tail in the male are bright orange, spotted with +black; in the female these parts are pale-greyish-green without spots." +(70. Bell, 'History of British Reptiles,' 2nd ed., 1849, p. 40.) We have +seen that the males alone of Sitana possess a throat-pouch; and this is +splendidly tinted with blue, black, and red. In the Proctotretus tenuis of +Chile the male alone is marked with spots of blue, green, and coppery-red. +(71. For Proctotretus, see 'Zoology of the Voyage of the "Beagle"; +Reptiles,' by Mr. Bell, p. 8. For the Lizards of S. Africa, see 'Zoology +of S. Africa: Reptiles,' by Sir Andrew Smith, pl. 25 and 39. For the +Indian Calotes, see 'Reptiles of British India,' by Dr. Gunther, p. 143.) +In many cases the males retain the same colours throughout the year, but in +others they become much brighter during the breeding-season; I may give as +an additional instance the Calotes maria, which at this season has a bright +red head, the rest of the body being green. (72. Gunther in 'Proceedings, +Zoological Society,' 1870, p. 778, with a coloured figure.) + +Both sexes of many species are beautifully coloured exactly alike; and +there is no reason to suppose that such colours are protective. No doubt +with the bright green kinds which live in the midst of vegetation, this +colour serves to conceal them; and in N. Patagonia I saw a lizard +(Proctotretus multimaculatus) which, when frightened, flattened its body, +closed its eyes, and then from its mottled tints was hardly distinguishable +from the surrounding sand. But the bright colours with which so many +lizards are ornamented, as well as their various curious appendages, were +probably acquired by the males as an attraction, and then transmitted +either to their male offspring alone, or to both sexes. Sexual selection, +indeed, seems to have played almost as important a part with reptiles as +with birds; and the less conspicuous colours of the females in comparison +with the males cannot be accounted for, as Mr. Wallace believes to be the +case with birds, by the greater exposure of the females to danger during +incubation. + + +CHAPTER XIII. + +SECONDARY SEXUAL CHARACTERS OF BIRDS. + +Sexual differences--Law of battle--Special weapons--Vocal organs-- +Instrumental music--Love-antics and dances--Decorations, permanent and +seasonal--Double and single annual moults--Display of ornaments by the +males. + +Secondary sexual characters are more diversified and conspicuous in birds, +though not perhaps entailing more important changes of structure, than in +any other class of animals. I shall, therefore, treat the subject at +considerable length. Male birds sometimes, though rarely, possess special +weapons for fighting with each other. They charm the female by vocal or +instrumental music of the most varied kinds. They are ornamented by all +sorts of combs, wattles, protuberances, horns, air-distended sacks, top- +knots, naked shafts, plumes and lengthened feathers gracefully springing +from all parts of the body. The beak and naked skin about the head, and +the feathers, are often gorgeously coloured. The males sometimes pay their +court by dancing, or by fantastic antics performed either on the ground or +in the air. In one instance, at least, the male emits a musky odour, which +we may suppose serves to charm or excite the female; for that excellent +observer, Mr. Ramsay (1. 'Ibis,' vol. iii. (new series), 1867, p. 414.), +says of the Australian musk-duck (Biziura lobata) that "the smell which the +male emits during the summer months is confined to that sex, and in some +individuals is retained throughout the year; I have never, even in the +breeding-season, shot a female which had any smell of musk." So powerful +is this odour during the pairing-season, that it can be detected long +before the bird can be seen. (2. Gould, 'Handbook of the Birds of +Australia,' 1865, vol. ii. p. 383.) On the whole, birds appear to be the +most aesthetic of all animals, excepting of course man, and they have +nearly the same taste for the beautiful as we have. This is shewn by our +enjoyment of the singing of birds, and by our women, both civilised and +savage, decking their heads with borrowed plumes, and using gems which are +hardly more brilliantly coloured than the naked skin and wattles of certain +birds. In man, however, when cultivated, the sense of beauty is manifestly +a far more complex feeling, and is associated with various intellectual +ideas. + +Before treating of the sexual characters with which we are here more +particularly concerned, I may just allude to certain differences between +the sexes which apparently depend on differences in their habits of life; +for such cases, though common in the lower, are rare in the higher classes. +Two humming-birds belonging to the genus Eustephanus, which inhabit the +island of Juan Fernandez, were long thought to be specifically distinct, +but are now known, as Mr. Gould informs me, to be the male and female of +the same species, and they differ slightly in the form of the beak. In +another genus of humming-birds (Grypus), the beak of the male is serrated +along the margin and hooked at the extremity, thus differing much from that +of the female. In the Neomorpha of New Zealand, there is, as we have seen, +a still wider difference in the form of the beak in relation to the manner +of feeding of the two sexes. Something of the same kind has been observed +with the goldfinch (Carduelis elegans), for I am assured by Mr. J. Jenner +Weir that the bird-catchers can distinguish the males by their slightly +longer beaks. The flocks of males are often found feeding on the seeds of +the teazle (Dipsacus), which they can reach with their elongated beaks, +whilst the females more commonly feed on the seeds of the betony or +Scrophularia. With a slight difference of this kind as a foundation, we +can see how the beaks of the two sexes might be made to differ greatly +through natural selection. In some of the above cases, however, it is +possible that the beaks of the males may have been first modified in +relation to their contests with other males; and that this afterwards led +to slightly changed habits of life. + +LAW OF BATTLE. + +Almost all male birds are extremely pugnacious, using their beaks, wings, +and legs for fighting together. We see this every spring with our robins +and sparrows. The smallest of all birds, namely the humming-bird, is one +of the most quarrelsome. Mr. Gosse (3. Quoted by Mr. Gould, 'Introduction +to the Trochilidae,' 1861, page 29.) describes a battle in which a pair +seized hold of each other's beaks, and whirled round and round, till they +almost fell to the ground; and M. Montes de Oca, in speaking or another +genus of humming-bird, says that two males rarely meet without a fierce +aerial encounter: when kept in cages "their fighting has mostly ended in +the splitting of the tongue of one of the two, which then surely dies from +being unable to feed." (4. Gould, ibid. p. 52.) With waders, the males +of the common water-hen (Gallinula chloropus) "when pairing, fight +violently for the females: they stand nearly upright in the water and +strike with their feet." Two were seen to be thus engaged for half an +hour, until one got hold of the head of the other, which would have been +killed had not the observer interfered; the female all the time looking on +as a quiet spectator. (5. W. Thompson, 'Natural History of Ireland: +Birds,' vol. ii. 1850, p. 327.) Mr. Blyth informs me that the males of an +allied bird (Gallicrex cristatus) are a third larger than the females, and +are so pugnacious during the breeding-season that they are kept by the +natives of Eastern Bengal for the sake of fighting. Various other birds +are kept in India for the same purpose, for instance, the bulbuls +(Pycnonotus hoemorrhous) which "fight with great spirit." (6. Jerdon, +'Birds of India,' 1863, vol. ii. p. 96.) + +[Fig. 37. The Ruff or Machetes pugnax (from Brehm's 'Thierleben').] + +The polygamous ruff (Machetes pugnax, Fig. 37) is notorious for his extreme +pugnacity; and in the spring, the males, which are considerably larger than +the females, congregate day after day at a particular spot, where the +females propose to lay their eggs. The fowlers discover these spots by the +turf being trampled somewhat bare. Here they fight very much like game- +cocks, seizing each other with their beaks and striking with their wings. +The great ruff of feathers round the neck is then erected, and according to +Col. Montagu "sweeps the ground as a shield to defend the more tender +parts"; and this is the only instance known to me in the case of birds of +any structure serving as a shield. The ruff of feathers, however, from its +varied and rich colours probably serves in chief part as an ornament. Like +most pugnacious birds, they seem always ready to fight, and when closely +confined, often kill each other; but Montagu observed that their pugnacity +becomes greater during the spring, when the long feathers on their necks +are fully developed; and at this period the least movement by any one bird +provokes a general battle. (7. Macgillivray, 'History of British Birds,' +vol. iv. 1852, pp. 177-181.) Of the pugnacity of web-footed birds, two +instances will suffice: in Guiana "bloody fights occur during the +breeding-season between the males of the wild musk-duck (Cairina moschata); +and where these fights have occurred the river is covered for some distance +with feathers." (8. Sir R. Schomburgk, in 'Journal of Royal Geographic +Society,' vol. xiii. 1843, p. 31.) Birds which seem ill-adapted for +fighting engage in fierce conflicts; thus the stronger males of the pelican +drive away the weaker ones, snapping with their huge beaks and giving heavy +blows with their wings. Male snipe fight together, "tugging and pushing +each other with their bills in the most curious manner imaginable." Some +few birds are believed never to fight; this is the case, according to +Audubon, with one of the woodpeckers of the United States (Picu sauratus), +although "the hens are followed by even half a dozen of their gay suitors." +(9. 'Ornithological Biography,' vol. i. p. 191. For pelicans and snipes, +see vol. iii. pp. 138, 477.) + +The males of many birds are larger than the females, and this no doubt is +the result of the advantage gained by the larger and stronger males over +their rivals during many generations. The difference in size between the +two sexes is carried to an extreme point in several Australian species; +thus the male musk-duck (Biziura), and the male Cincloramphus cruralis +(allied to our pipits) are by measurement actually twice as large as their +respective females. (10. Gould, 'Handbook of Birds of Australia,' vol. i. +p. 395; vol. ii. p. 383.) With many other birds the females are larger +than the males; and, as formerly remarked, the explanation often given, +namely, that the females have most of the work in feeding their young, will +not suffice. In some few cases, as we shall hereafter see, the females +apparently have acquired their greater size and strength for the sake of +conquering other females and obtaining possession of the males. + +The males of many gallinaceous birds, especially of the polygamous kinds, +are furnished with special weapons for fighting with their rivals, namely +spurs, which can be used with fearful effect. It has been recorded by a +trustworthy writer (11. Mr. Hewitt, in the 'Poultry Book' by Tegetmeier, +1866, p. 137.) that in Derbyshire a kite struck at a game-hen accompanied +by her chickens, when the cock rushed to the rescue, and drove his spur +right through the eye and skull of the aggressor. The spur was with +difficulty drawn from the skull, and as the kite, though dead, retained his +grasp, the two birds were firmly locked together; but the cock when +disentangled was very little injured. The invincible courage of the game- +cock is notorious: a gentleman who long ago witnessed the brutal scene, +told me that a bird had both its legs broken by some accident in the +cockpit, and the owner laid a wager that if the legs could be spliced so +that the bird could stand upright, he would continue fighting. This was +effected on the spot, and the bird fought with undaunted courage until he +received his death-stroke. In Ceylon a closely allied, wild species, the +Gallus Stanleyi, is known to fight desperately "in defence of his +seraglio," so that one of the combatants is frequently found dead. (12. +Layard, 'Annals and Magazine of Natural History,' vol. xiv. 1854, p. 63.) +An Indian partridge (Ortygornis gularis), the male of which is furnished +with strong and sharp spurs, is so quarrelsome "that the scars of former +fights disfigure the breast of almost every bird you kill." (13. Jerdon, +'Birds of India,' vol. iii. p. 574.) + +The males of almost all gallinaceous birds, even those which are not +furnished with spurs, engage during the breeding-season in fierce +conflicts. The Capercailzie and Black-cock (Tetrao urogallus and T. +tetrix), which are both polygamists, have regular appointed places, where +during many weeks they congregate in numbers to fight together and to +display their charms before the females. Dr. W. Kovalevsky informs me that +in Russia he has seen the snow all bloody on the arenas where the +capercailzie have fought; and the black-cocks "make the feathers fly in +every direction," when several "engage in a battle royal." The elder Brehm +gives a curious account of the Balz, as the love-dances and love-songs of +the Black-cock are called in Germany. The bird utters almost continuously +the strangest noises: "he holds his tail up and spreads it out like a fan, +he lifts up his head and neck with all the feathers erect, and stretches +his wings from the body. Then he takes a few jumps in different +directions, sometimes in a circle, and presses the under part of his beak +so hard against the ground that the chin feathers are rubbed off. During +these movements he beats his wings and turns round and round. The more +ardent he grows the more lively he becomes, until at last the bird appears +like a frantic creature." At such times the black-cocks are so absorbed +that they become almost blind and deaf, but less so than the capercailzie: +hence bird after bird may be shot on the same spot, or even caught by the +hand. After performing these antics the males begin to fight: and the +same black-cock, in order to prove his strength over several antagonists, +will visit in the course of one morning several Balz-places, which remain +the same during successive years. (14. Brehm, 'Thierleben,' 1867, B. iv. +s. 351. Some of the foregoing statements are taken from L. Lloyd, 'The +Game Birds of Sweden,' etc., 1867, p. 79.) + +The peacock with his long train appears more like a dandy than a warrior, +but he sometimes engages in fierce contests: the Rev. W. Darwin Fox +informs me that at some little distance from Chester two peacocks became so +excited whilst fighting, that they flew over the whole city, still engaged, +until they alighted on the top of St. John's tower. + +The spur, in those gallinaceous birds which are thus provided, is generally +single; but Polyplectron (Fig. 51) has two or more on each leg; and one of +the Blood-pheasants (Ithaginis cruentus) has been seen with five spurs. +The spurs are generally confined to the male, being represented by mere +knobs or rudiments in the female; but the females of the Java peacock (Pavo +muticus) and, as I am informed by Mr. Blyth, of the small fire-backed +pheasant (Euplocamus erythrophthalmus) possess spurs. In Galloperdix it is +usual for the males to have two spurs, and for the females to have only one +on each leg. (15. Jerdon, 'Birds of India': on Ithaginis, vol. iii. p. +523; on Galloperdix, p. 541.) Hence spurs may be considered as a masculine +structure, which has been occasionally more or less transferred to the +females. Like most other secondary sexual characters, the spurs are highly +variable, both in number and development, in the same species. + +[Fig.38. Palamedea cornuta (from Brehm), shewing the double wing-spurs, +and the filament on the head.] + +Various birds have spurs on their wings. But the Egyptian goose +(Chenalopex aegyptiacus) has only "bare obtuse knobs," and these probably +shew us the first steps by which true spurs have been developed in other +species. In the spur-winged goose, Plectropterus gambensis, the males have +much larger spurs than the females; and they use them, as I am informed by +Mr. Bartlett, in fighting together, so that, in this case, the wing-spurs +serve as sexual weapons; but according to Livingstone, they are chiefly +used in the defence of the young. The Palamedea (Fig. 38) is armed with a +pair of spurs on each wing; and these are such formidable weapons that a +single blow has been known to drive a dog howling away. But it does not +appear that the spurs in this case, or in that of some of the spur-winged +rails, are larger in the male than in the female. (16. For the Egyptian +goose, see Macgillivray, 'British Birds,' vol. iv. p. 639. For +Plectropterus, Livingstone's 'Travels,' p. 254. For Palamedea, Brehm's +'Thierleben,' B. iv. s. 740. See also on this bird Azara, 'Voyages dans +l'Amerique merid.' tom. iv. 1809, pp. 179, 253.) In certain plovers, +however, the wing-spurs must be considered as a sexual character. Thus in +the male of our common peewit (Vanellus cristatus) the tubercle on the +shoulder of the wing becomes more prominent during the breeding-season, and +the males fight together. In some species of Lobivanellus a similar +tubercle becomes developed during the breeding-season "into a short horny +spur." In the Australian L. lobatus both sexes have spurs, but these are +much larger in the males than in the females. In an allied bird, the +Hoplopterus armatus, the spurs do not increase in size during the breeding- +season; but these birds have been seen in Egypt to fight together, in the +same manner as our peewits, by turning suddenly in the air and striking +sideways at each other, sometimes with fatal results. Thus also they drive +away other enemies. (17. See, on our peewit, Mr. R. Carr in 'Land and +Water,' Aug. 8th, 1868, p. 46. In regard to Lobivanellus, see Jerdon's +'Birds of India,' vol. iii. p. 647, and Gould's 'Handbook of Birds of +Australia,' vol. ii. p. 220. For the Hoplopterus, see Mr. Allen in the +'Ibis,' vol. v. 1863, p. 156.) + +The season of love is that of battle; but the males of some birds, as of +the game-fowl and ruff, and even the young males of the wild turkey and +grouse (18. Audubon, 'Ornithological Biography,' vol. ii. p. 492; vol. i. +pp. 4-13.), are ready to fight whenever they meet. The presence of the +female is the teterrima belli causa. The Bengali baboos make the pretty +little males of the amadavat (Estrelda amandava) fight together by placing +three small cages in a row, with a female in the middle; after a little +time the two males are turned loose, and immediately a desperate battle +ensues. (19. Mr. Blyth, 'Land and Water,' 1867, p. 212.) When many males +congregate at the same appointed spot and fight together, as in the case of +grouse and various other birds, they are generally attended by the females +(20. Richardson on Tetrao umbellus, 'Fauna Bor. Amer.: Birds,' 1831, p. +343. L. Lloyd, 'Game Birds of Sweden,' 1867, pp. 22, 79, on the +capercailzie and black-cock. Brehm, however, asserts ('Thierleben,' B. iv. +s. 352) that in Germany the grey-hens do not generally attend the Balzen of +the black-cocks, but this is an exception to the common rule; possibly the +hens may lie hidden in the surrounding bushes, as is known to be the case +with the gray-hens in Scandinavia, and with other species in N. America.), +which afterwards pair with the victorious combatants. But in some cases +the pairing precedes instead of succeeding the combat: thus according to +Audubon (21. 'Ornithological Biography,' vol. ii. p. 275.), several males +of the Virginian goat-sucker (Caprimulgus virgianus) "court, in a highly +entertaining manner the female, and no sooner has she made her choice, than +her approved gives chase to all intruders, and drives them beyond his +dominions." Generally the males try to drive away or kill their rivals +before they pair. It does not, however, appear that the females invariably +prefer the victorious males. I have indeed been assured by Dr. W. +Kovalevsky that the female capercailzie sometimes steals away with a young +male who has not dared to enter the arena with the older cocks, in the same +manner as occasionally happens with the does of the red-deer in Scotland. +When two males contend in presence of a single female, the victor, no +doubt, commonly gains his desire; but some of these battles are caused by +wandering males trying to distract the peace of an already mated pair. +(22. Brehm, 'Thierleben,' etc., B. iv. 1867, p. 990. Audubon, +'Ornithological Biography,' vol. ii. p. 492.) + +Even with the most pugnacious species it is probable that the pairing does +not depend exclusively on the mere strength and courage of the male; for +such males are generally decorated with various ornaments, which often +become more brilliant during the breeding-season, and which are sedulously +displayed before the females. The males also endeavour to charm or excite +their mates by love-notes, songs, and antics; and the courtship is, in many +instances, a prolonged affair. Hence it is not probable that the females +are indifferent to the charms of the opposite sex, or that they are +invariably compelled to yield to the victorious males. It is more probable +that the females are excited, either before or after the conflict, by +certain males, and thus unconsciously prefer them. In the case of Tetrao +umbellus, a good observer (23. 'Land and Water,' July 25, 1868, p. 14.) +goes so far as to believe that the battles of the male "are all a sham, +performed to show themselves to the greatest advantage before the admiring +females who assemble around; for I have never been able to find a maimed +hero, and seldom more than a broken feather." I shall have to recur to +this subject, but I may here add that with the Tetrao cupido of the United +States, about a score of males assemble at a particular spot, and, +strutting about, make the whole air resound with their extraordinary +noises. At the first answer from a female the males begin to fight +furiously, and the weaker give way; but then, according to Audubon, both +the victors and vanquished search for the female, so that the females must +either then exert a choice, or the battle must be renewed. So, again, with +one of the field-starlings of the United States (Sturnella ludoviciana) the +males engage in fierce conflicts, "but at the sight of a female they all +fly after her as if mad." (24. Audubon's 'Ornithological Biography;' on +Tetrao cupido, vol. ii. p. 492; on the Sturnus, vol. ii. p. 219.) + +VOCAL AND INSTRUMENTAL MUSIC. + +With birds the voice serves to express various emotions, such as distress, +fear, anger, triumph, or mere happiness. It is apparently sometimes used +to excite terror, as in the case of the hissing noise made by some +nestling-birds. Audubon (25. 'Ornithological Biography,' vol. v. p. +601.), relates that a night-heron (Ardea nycticorax, Linn.), which he kept +tame, used to hide itself when a cat approached, and then "suddenly start +up uttering one of the most frightful cries, apparently enjoying the cat's +alarm and flight." The common domestic cock clucks to the hen, and the hen +to her chickens, when a dainty morsel is found. The hen, when she has laid +an egg, "repeats the same note very often, and concludes with the sixth +above, which she holds for a longer time" (26. The Hon. Daines Barrington, +'Philosophical Transactions,' 1773, p. 252.); and thus she expresses her +joy. Some social birds apparently call to each other for aid; and as they +flit from tree to tree, the flock is kept together by chirp answering +chirp. During the nocturnal migrations of geese and other water-fowl, +sonorous clangs from the van may be heard in the darkness overhead, +answered by clangs in the rear. Certain cries serve as danger signals, +which, as the sportsman knows to his cost, are understood by the same +species and by others. The domestic cock crows, and the humming-bird +chirps, in triumph over a defeated rival. The true song, however, of most +birds and various strange cries are chiefly uttered during the breeding- +season, and serve as a charm, or merely as a call-note, to the other sex. + +Naturalists are much divided with respect to the object of the singing of +birds. Few more careful observers ever lived than Montagu, and he +maintained that the "males of song-birds and of many others do not in +general search for the female, but, on the contrary, their business in the +spring is to perch on some conspicuous spot, breathing out their full and +armorous notes, which, by instinct, the female knows, and repairs to the +spot to choose her mate." (27. 'Ornithological Dictionary,' 1833, p. +475.) Mr. Jenner Weir informs me that this is certainly the case with the +nightingale. Bechstein, who kept birds during his whole life, asserts, +"that the female canary always chooses the best singer, and that in a state +of nature the female finch selects that male out of a hundred whose notes +please her most. (28. 'Naturgeschichte der Stubenvögel,' 1840, s. 4. +Mr. Harrison Weir likewise writes to me:--"I am informed that the best +singing males generally get a mate first, when they are bred in the same +room.") There can be no doubt that birds closely attend to each other's +song. Mr. Weir has told me of the case of a bullfinch which had been +taught to pipe a German waltz, and who was so good a performer that he cost +ten guineas; when this bird was first introduced into a room where other +birds were kept and he began to sing, all the others, consisting of about +twenty linnets and canaries, ranged themselves on the nearest side of their +cages, and listened with the greatest interest to the new performer. Many +naturalists believe that the singing of birds is almost exclusively "the +effect of rivalry and emulation," and not for the sake of charming their +mates. This was the opinion of Daines Barrington and White of Selborne, +who both especially attended to this subject. (29. 'Philosophical +Transactions,' 1773, p. 263. White's 'Natural History of Selborne,' 1825, +vol. i. p. 246.) Barrington, however, admits that "superiority in song +gives to birds an amazing ascendancy over others, as is well known to bird- +catchers." + +It is certain that there is an intense degree of rivalry between the males +in their singing. Bird-fanciers match their birds to see which will sing +longest; and I was told by Mr. Yarrell that a first-rate bird will +sometimes sing till he drops down almost dead, or according to Bechstein +(30. 'Naturgesch. der Stubenvögel,' 1840, s. 252.), quite dead from +rupturing a vessel in the lungs. Whatever the cause may be, male birds, as +I hear from Mr. Weir, often die suddenly during the season of song. That +the habit of singing is sometimes quite independent of love is clear, for a +sterile, hybrid canary-bird has been described (31. Mr. Bold, 'Zoologist,' +1843-44, p. 659.) as singing whilst viewing itself in a mirror, and then +dashing at its own image; it likewise attacked with fury a female canary, +when put into the same cage. The jealousy excited by the act of singing is +constantly taken advantage of by bird-catchers; a male, in good song, is +hidden and protected, whilst a stuffed bird, surrounded by limed twigs, is +exposed to view. In this manner, as Mr. Weir informs me, a man has in the +course of a single day caught fifty, and in one instance, seventy, male +chaffinches. The power and inclination to sing differ so greatly with +birds that although the price of an ordinary male chaffinch is only +sixpence, Mr. Weir saw one bird for which the bird-catcher asked three +pounds; the test of a really good singer being that it will continue to +sing whilst the cage is swung round the owner's head. + +That male birds should sing from emulation as well as for charming the +female, is not at all incompatible; and it might have been expected that +these two habits would have concurred, like those of display and pugnacity. +Some authors, however, argue that the song of the male cannot serve to +charm the female, because the females of some few species, such as of the +canary, robin, lark, and bullfinch, especially when in a state of +widowhood, as Bechstein remarks, pour forth fairly melodious strains. In +some of these cases the habit of singing may be in part attributed to the +females having been highly fed and confined (32. D. Barrington, +'Philosophical Transactions,' 1773, p. 262. Bechstein, 'Stubenvögel,' +1840, s. 4.), for this disturbs all the functions connected with the +reproduction of the species. Many instances have already been given of the +partial transference of secondary masculine characters to the female, so +that it is not at all surprising that the females of some species should +possess the power of song. It has also been argued, that the song of the +male cannot serve as a charm, because the males of certain species, for +instance of the robin, sing during the autumn. (33. This is likewise the +case with the water-ouzel; see Mr. Hepburn in the 'Zoologist,' 1845-46, p. +1068.) But nothing is more common than for animals to take pleasure in +practising whatever instinct they follow at other times for some real good. +How often do we see birds which fly easily, gliding and sailing through the +air obviously for pleasure? The cat plays with the captured mouse, and the +cormorant with the captured fish. The weaver-bird (Ploceus), when confined +in a cage, amuses itself by neatly weaving blades of grass between the +wires of its cage. Birds which habitually fight during the breeding-season +are generally ready to fight at all times; and the males of the +capercailzie sometimes hold their Balzen or leks at the usual place of +assemblage during the autumn. (34. L. Lloyd, 'Game Birds of Sweden,' +1867, p. 25.) Hence it is not at all surprising that male birds should +continue singing for their own amusement after the season for courtship is +over. + +As shewn in a previous chapter, singing is to a certain extent an art, and +is much improved by practice. Birds can be taught various tunes, and even +the unmelodious sparrow has learnt to sing like a linnet. They acquire the +song of their foster parents (35. Barrington, ibid. p. 264, Bechstein, +ibid. s. 5.), and sometimes that of their neighbours. (36. Dureau de la +Malle gives a curious instance ('Annales des Sc. Nat.' 3rd series, Zoolog., +tom. x. p. 118) of some wild blackbirds in his garden in Paris, which +naturally learnt a republican air from a caged bird.) All the common +songsters belong to the Order of Insessores, and their vocal organs are +much more complex than those of most other birds; yet it is a singular fact +that some of the Insessores, such as ravens, crows, and magpies, possess +the proper apparatus (37. Bishop, in 'Todd's Cyclopaedia of Anatomy and +Physiology,' vol. iv. p. 1496.), though they never sing, and do not +naturally modulate their voices to any great extent. Hunter asserts (38. +As stated by Barrington in 'Philosophical Transactions,' 1773, p. 262.) +that with the true songsters the muscles of the larynx are stronger in the +males than in the females; but with this slight exception there is no +difference in the vocal organs of the two sexes, although the males of most +species sing so much better and more continuously than the females. + +It is remarkable that only small birds properly sing. The Australian genus +Menura, however, must be excepted; for the Menura Alberti, which is about +the size of a half-grown turkey, not only mocks other birds, but "its own +whistle is exceedingly beautiful and varied." The males congregate and +form "corroborying places," where they sing, raising and spreading their +tails like peacocks, and drooping their wings. (39. Gould, 'Handbook to +the Birds of Australia,' vol. i. 1865, pp. 308-310. See also Mr. T.W. Wood +in the 'Student,' April 1870, p. 125.) It is also remarkable that birds +which sing well are rarely decorated with brilliant colours or other +ornaments. Of our British birds, excepting the bullfinch and goldfinch, +the best songsters are plain-coloured. The kingfisher, bee-eater, roller, +hoopoe, woodpeckers, etc., utter harsh cries; and the brilliant birds of +the tropics are hardly ever songsters. (40. See remarks to this effect in +Gould's 'Introduction to the Trochilidae,' 1861, p. 22.) Hence bright +colours and the power of song seem to replace each other. We can perceive +that if the plumage did not vary in brightness, or if bright colours were +dangerous to the species, other means would be employed to charm the +females; and melody of voice offers one such means. + +[Fig. 39. Tetrao cupido: male. (T.W. Wood.)] + +In some birds the vocal organs differ greatly in the two sexes. In the +Tetrao cupido (Fig. 39) the male has two bare, orange-coloured sacks, one +on each side of the neck; and these are largely inflated when the male, +during the breeding-season, makes his curious hollow sound, audible at a +great distance. Audubon proved that the sound was intimately connected +with this apparatus (which reminds us of the air-sacks on each side of the +mouth of certain male frogs), for he found that the sound was much +diminished when one of the sacks of a tame bird was pricked, and when both +were pricked it was altogether stopped. The female has "a somewhat +similar, though smaller naked space of skin on the neck; but this is not +capable of inflation." (41. 'The Sportsman and Naturalist in Canada,' by +Major W. Ross King, 1866, pp. 144-146. Mr. T.W. Wood gives in the +'Student' (April 1870, p. 116) an excellent account of the attitude and +habits of this bird during its courtship. He states that the ear-tufts or +neck-plumes are erected, so that they meet over the crown of the head. See +his drawing, Fig. 39.) The male of another kind of grouse (Tetrao +urophasianus), whilst courting the female, has his "bare yellow oesophagus +inflated to a prodigious size, fully half as large as the body"; and he +then utters various grating, deep, hollow tones. With his neck-feathers +erect, his wings lowered, and buzzing on the ground, and his long pointed +tail spread out like a fan, he displays a variety of grotesque attitudes. +The oesophagus of the female is not in any way remarkable. (42. +Richardson, 'Fauna Bor. American: Birds,' 1831, p. 359. Audubon, ibid. +vol. iv. p. 507.) + +[Fig. 40. The Umbrella-bird or Cephalopterus ornatus, male (from Brehm).] + +It seems now well made out that the great throat pouch of the European male +bustard (Otis tarda), and of at least four other species, does not, as was +formerly supposed, serve to hold water, but is connected with the utterance +during the breeding-season of a peculiar sound resembling "oak." (43. The +following papers have been lately written on this subject: Prof. A. +Newton, in the 'Ibis,' 1862, p. 107; Dr. Cullen, ibid. 1865, p. 145; Mr. +Flower, in 'Proc. Zool. Soc.' 1865, p. 747; and Dr. Murie, in 'Proc. Zool. +Soc.' 1868, p. 471. In this latter paper an excellent figure is given of +the male Australian Bustard in full display with the sack distended. It is +a singular fact that the sack is not developed in all the males of the same +species.) A crow-like bird inhabiting South America (see Cephalopterus +ornatus, Fig. 40) is called the umbrella-bird, from its immense top knot, +formed of bare white quills surmounted by dark-blue plumes, which it can +elevate into a great dome no less than five inches in diameter, covering +the whole head. This bird has on its neck a long, thin, cylindrical fleshy +appendage, which is thickly clothed with scale-like blue feathers. It +probably serves in part as an ornament, but likewise as a resounding +apparatus; for Mr. Bates found that it is connected "with an unusual +development of the trachea and vocal organs." It is dilated when the bird +utters its singularly deep, loud and long sustained fluty note. The head- +crest and neck-appendage are rudimentary in the female. (44. Bates, 'The +Naturalist on the Amazons,' 1863, vol. ii. p. 284; Wallace, in +'Proceedings, Zoological Society,' 1850, p. 206. A new species, with a +still larger neck-appendage (C. penduliger), has lately been discovered, +see 'Ibis,' vol. i. p. 457.) + +The vocal organs of various web-footed and wading birds are extraordinarily +complex, and differ to a certain extent in the two sexes. In some cases +the trachea is convoluted, like a French horn, and is deeply embedded in +the sternum. In the wild swan (Cygnus ferus) it is more deeply embedded in +the adult male than in the adult female or young male. In the male +Merganser the enlarged portion of the trachea is furnished with an +additional pair of muscles. (45. Bishop, in Todd's 'Cyclopaedia of +Anatomy and Physiology,' vol. iv. p. 1499.) In one of the ducks, however, +namely Anas punctata, the bony enlargement is only a little more developed +in the male than in the female. (46. Prof. Newton, 'Proc. Zoolog. Soc.' +1871, p. 651.) But the meaning of these differences in the trachea of the +two sexes of the Anatidae is not understood; for the male is not always the +more vociferous; thus with the common duck, the male hisses, whilst the +female utters a loud quack. (47. The spoonbill (Platalea) has its trachea +convoluted into a figure of eight, and yet this bird (Jerdon, 'Birds of +India,' vol. iii. p. 763) is mute; but Mr. Blyth informs me that the +convolutions are not constantly present, so that perhaps they are now +tending towards abortion.) In both sexes of one of the cranes (Grus virgo) +the trachea penetrates the sternum, but presents "certain sexual +modifications." In the male of the black stork there is also a well-marked +sexual difference in the length and curvature of the bronchi. (48. +'Elements of Comparative Anatomy,' by R. Wagner, Eng. translat. 1845, p. +111. With respect to the swan, as given above, Yarrell's 'History of +British Birds,' 2nd edition, 1845, vol. iii. p. 193.) Highly important +structures have, therefore, in these cases been modified according to sex. + +It is often difficult to conjecture whether the many strange cries and +notes uttered by male birds during the breeding-season serve as a charm or +merely as a call to the female. The soft cooing of the turtle-dove and of +many pigeons, it may be presumed, pleases the female. When the female of +the wild turkey utters her call in the morning, the male answers by a note +which differs from the gobbling noise made, when with erected feathers, +rustling wings and distended wattles, he puffs and struts before her. (49. +C.L. Bonaparte, quoted in the 'Naturalist Library: Birds,' vol. xiv. p. +126.) The spel of the black-cock certainly serves as a call to the female, +for it has been known to bring four or five females from a distance to a +male under confinement; but as the black-cock continues his spel for hours +during successive days, and in the case of the capercailzie "with an agony +of passion," we are led to suppose that the females which are present are +thus charmed. (50. L. Lloyd, 'The Game Birds of Sweden,' etc., 1867, pp. +22, 81.) The voice of the common rook is known to alter during the +breeding-season, and is therefore in some way sexual. (51. Jenner, +'Philosophical Transactions,' 1824, p. 20.) But what shall we say about +the harsh screams of, for instance, some kinds of macaws; have these birds +as bad taste for musical sounds as they apparently have for colour, judging +by the inharmonious contrast of their bright yellow and blue plumage? It +is indeed possible that without any advantage being thus gained, the loud +voices of many male birds may be the result of the inherited effects of the +continued use of their vocal organs when excited by the strong passions of +love, jealousy and rage; but to this point we shall recur when we treat of +quadrupeds. + +We have as yet spoken only of the voice, but the males of various birds +practise, during their courtship, what may be called instrumental music. +Peacocks and Birds of Paradise rattle their quills together. Turkey-cocks +scrape their wings against the ground, and some kinds of grouse thus +produce a buzzing sound. Another North American grouse, the Tetrao +umbellus, when with his tail erect, his ruffs displayed, "he shows off his +finery to the females, who lie hid in the neighbourhood," drums by rapidly +striking his wings together above his back, according to Mr. R. Haymond, +and not, as Audubon thought, by striking them against his sides. The sound +thus produced is compared by some to distant thunder, and by others to the +quick roll of a drum. The female never drums, "but flies directly to the +place where the male is thus engaged." The male of the Kalij-pheasant, in +the Himalayas, often makes a singular drumming noise with his wings, not +unlike the sound produced by shaking a stiff piece of cloth." On the west +coast of Africa the little black-weavers (Ploceus?) congregate in a small +party on the bushes round a small open space, and sing and glide through +the air with quivering wings, "which make a rapid whirring sound like a +child's rattle." One bird after another thus performs for hours together, +but only during the courting-season. At this season, and at no other time, +the males of certain night-jars (Caprimulgus) make a strange booming noise +with their wings. The various species of woodpeckers strike a sonorous +branch with their beaks, with so rapid a vibratory movement that "the head +appears to be in two places at once." The sound thus produced is audible +at a considerable distance but cannot be described; and I feel sure that +its source would never be conjectured by any one hearing it for the first +time. As this jarring sound is made chiefly during the breeding-season, it +has been considered as a love-song; but it is perhaps more strictly a love- +call. The female, when driven from her nest, has been observed thus to +call her mate, who answered in the same manner and soon appeared. Lastly, +the male hoopoe (Upupa epops) combines vocal and instrumental music; for +during the breeding-season this bird, as Mr. Swinhoe observed, first draws +in air, and then taps the end of its beak perpendicularly down against a +stone or the trunk of a tree, "when the breath being forced down the +tubular bill produces the correct sound." If the beak is not thus struck +against some object, the sound is quite different. Air is at the same time +swallowed, and the oesophagus thus becomes much swollen; and this probably +acts as a resonator, not only with the hoopoe, but with pigeons and other +birds. (52. For the foregoing facts see, on Birds of Paradise, Brehm, +'Thierleben,' Band iii. s. 325. On Grouse, Richardson, 'Fauna Bor. +Americ.: Birds,' pp. 343 and 359; Major W. Ross King, 'The Sportsman in +Canada,' 1866, p. 156; Mr. Haymond, in Prof. Cox's 'Geol. Survey of +Indiana,' p. 227; Audubon, 'American Ornitholog. Biograph.' vol. i. p. 216. +On the Kalij-pheasant, Jerdon, 'Birds of India,' vol. iii. p. 533. On the +Weavers, Livingstone's 'Expedition to the Zambesi,' 1865, p. 425. On +Woodpeckers, Macgillivray, 'Hist. of British Birds,' vol. iii. 1840, pp. +84, 88, 89, and 95. On the Hoopoe, Mr. Swinhoe, in 'Proc. Zoolog. Soc.' +June 23, 1863 and 1871, p. 348. On the Night-jar, Audubon, ibid. vol. ii. +p. 255, and 'American Naturalist,' 1873, p. 672. The English Night-jar +likewise makes in the spring a curious noise during its rapid flight.) + +[Fig. 41. Outer tail-feather of Scolopax gallinago (from 'Proc. Zool. +Soc.' 1858). + +Fig. 42. Outer tail-feather of Scolopax frenata. + +Fig. 43. Outer tail-feather of Scolopax javensis.] + +In the foregoing cases sounds are made by the aid of structures already +present and otherwise necessary; but in the following cases certain +feathers have been specially modified for the express purpose of producing +sounds. The drumming, bleating, neighing, or thundering noise (as +expressed by different observers) made by the common snipe (Scolopax +gallinago) must have surprised every one who has ever heard it. This bird, +during the pairing-season, flies to "perhaps a thousand feet in height," +and after zig-zagging about for a time descends to the earth in a curved +line, with outspread tail and quivering pinions, and surprising velocity. +The sound is emitted only during this rapid descent. No one was able to +explain the cause until M. Meves observed that on each side of the tail the +outer feathers are peculiarly formed (Fig. 41), having a stiff sabre-shaped +shaft with the oblique barbs of unusual length, the outer webs being +strongly bound together. He found that by blowing on these feathers, or by +fastening them to a long thin stick and waving them rapidly through the +air, he could reproduce the drumming noise made by the living bird. Both +sexes are furnished with these feathers, but they are generally larger in +the male than in the female, and emit a deeper note. In some species, as +in S. frenata (Fig. 42), four feathers, and in S. javensis (Fig. 43), no +less than eight on each side of the tail are greatly modified. Different +tones are emitted by the feathers of the different species when waved +through the air; and the Scolopax Wilsonii of the United States makes a +switching noise whilst descending rapidly to the earth. (53. See M. +Meves' interesting paper in 'Proc. Zool. Soc.' 1858, p. 199. For the +habits of the snipe, Macgillivray, 'History of British Birds,' vol. iv. p. +371. For the American snipe, Capt. Blakiston, 'Ibis,' vol. v. 1863, p. +131.) + +[Fig. 44. Primary wing-feather of a Humming-bird, the Selasphorus +platycercus (from a sketch by Mr. Salvin). +Upper figure, that of male; +lower figure, corresponding feather of female.] + +In the male of the Chamaepetes unicolor (a large gallinaceous bird of +America), the first primary wing-feather is arched towards the tip and is +much more attenuated than in the female. In an allied bird, the Penelope +nigra, Mr. Salvin observed a male, which, whilst it flew downwards "with +outstretched wings, gave forth a kind of crashing rushing noise," like the +falling of a tree. (54. Mr. Salvin, in 'Proceedings, Zoological Society,' +1867, p. 160. I am much indebted to this distinguished ornithologist for +sketches of the feathers of the Chamaepetes, and for other information.) +The male alone of one of the Indian bustards (Sypheotides auritus) has its +primary wing-feathers greatly acuminated; and the male of an allied species +is known to make a humming noise whilst courting the female. (55. Jerdon, +'Birds of India,' vol. iii. pp. 618, 621.) In a widely different group of +birds, namely Humming-birds, the males alone of certain kinds have either +the shafts of their primary wing-feathers broadly dilated, or the webs +abruptly excised towards the extremity. The male, for instance, of +Selasphorus platycercus, when adult, has the first primary wing-feather +(Fig. 44), thus excised. Whilst flying from flower to flower he makes "a +shrill, almost whistling noise" (56. Gould, 'Introduction to the +Trochilidae,' 1861, p. 49. Salvin, 'Proceedings, Zoological Society,' +1867, p. 160.); but it did not appear to Mr. Salvin that the noise was +intentionally made. + +[Fig. 45. Secondary wing-feathers of Pipra deliciosa (from Mr. Sclater, in +'Proc. Zool. Soc.' 1860). +The three upper feathers, a, b, c, from the male; +the three lower corresponding feathers, d, e, f, from the female. +a and d, fifth secondary wing-feather of male and female, upper surface. +b and e, sixth secondary, upper surface. +c and f, seventh secondary, lower surface.] + +Lastly, in several species of a sub-genus of Pipra or Manakin, the males, +as described by Mr. Sclater, have their SECONDARY wing-feathers modified in +a still more remarkable manner. In the brilliantly-coloured P. deliciosa +the first three secondaries are thick-stemmed and curved towards the body; +in the fourth and fifth (Fig. 45, a) the change is greater; and in the +sixth and seventh (b, c) the shaft "is thickened to an extraordinary +degree, forming a solid horny lump." The barbs also are greatly changed in +shape, in comparison with the corresponding feathers (d, e, f) in the +female. Even the bones of the wing, which support these singular feathers +in the male, are said by Mr. Fraser to be much thickened. These little +birds make an extraordinary noise, the first "sharp note being not unlike +the crack of a whip." (57. Sclater, in 'Proceedings, Zoological Society,' +1860, p. 90, and in 'Ibis,' vol. iv. 1862, p. 175. Also Salvin, in 'Ibis,' +1860, p. 37.) + +The diversity of the sounds, both vocal and instrumental, made by the males +of many birds during the breeding-season, and the diversity of the means +for producing such sounds, are highly remarkable. We thus gain a high idea +of their importance for sexual purposes, and are reminded of the conclusion +arrived at as to insects. It is not difficult to imagine the steps by +which the notes of a bird, primarily used as a mere call or for some other +purpose, might have been improved into a melodious love song. In the case +of the modified feathers, by which the drumming, whistling, or roaring +noises are produced, we know that some birds during their courtship +flutter, shake, or rattle their unmodified feathers together; and if the +females were led to select the best performers, the males which possessed +the strongest or thickest, or most attenuated feathers, situated on any +part of the body, would be the most successful; and thus by slow degrees +the feathers might be modified to almost any extent. The females, of +course, would not notice each slight successive alteration in shape, but +only the sounds thus produced. It is a curious fact that in the same class +of animals, sounds so different as the drumming of the snipe's tail, the +tapping of the woodpecker's beak, the harsh trumpet-like cry of certain +water-fowl, the cooing of the turtle-dove, and the song of the nightingale, +should all be pleasing to the females of the several species. But we must +not judge of the tastes of distinct species by a uniform standard; nor must +we judge by the standard of man's taste. Even with man, we should remember +what discordant noises, the beating of tom-toms and the shrill notes of +reeds, please the ears of savages. Sir S. Baker remarks (58. 'The Nile +Tributaries of Abyssinia,' 1867, p. 203.), that "as the stomach of the Arab +prefers the raw meat and reeking liver taken hot from the animal, so does +his ear prefer his equally coarse and discordant music to all other." + +LOVE ANTICS AND DANCES. + +The curious love gestures of some birds have already been incidentally +noticed; so that little need here be added. In Northern America large +numbers of a grouse, the Tetrao phasianellus, meet every morning during the +breeding-season on a selected level spot, and here they run round and round +in a circle of about fifteen or twenty feet in diameter, so that the ground +is worn quite bare, like a fairy-ring. In these Partridge-dances, as they +are called by the hunters, the birds assume the strangest attitudes, and +run round, some to the left and some to the right. Audubon describes the +males of a heron (Ardea herodias) as walking about on their long legs with +great dignity before the females, bidding defiance to their rivals. With +one of the disgusting carrion-vultures (Cathartes jota) the same naturalist +states that "the gesticulations and parade of the males at the beginning of +the love-season are extremely ludicrous." Certain birds perform their +love-antics on the wing, as we have seen with the black African weaver, +instead of on the ground. During the spring our little white-throat +(Sylvia cinerea) often rises a few feet or yards in the air above some +bush, and "flutters with a fitful and fantastic motion, singing all the +while, and then drops to its perch." The great English bustard throws +himself into indescribably odd attitudes whilst courting the female, as has +been figured by Wolf. An allied Indian bustard (Otis bengalensis) at such +times "rises perpendicularly into the air with a hurried flapping of his +wings, raising his crest and puffing out the feathers of his neck and +breast, and then drops to the ground;" he repeats this manoeuvre several +times, at the same time humming in a peculiar tone. Such females as happen +to be near "obey this saltatory summons," and when they approach he trails +his wings and spreads his tail like a turkey-cock. (59. For Tetrao +phasianellus, see Richardson, 'Fauna, Bor. America,' p. 361, and for +further particulars Capt. Blakiston, 'Ibis,' 1863, p. 125. For the +Cathartes and Ardea, Audubon, 'Ornithological Biography,' vol. ii. p. 51, +and vol. iii. p. 89. On the White-throat, Macgillivray, 'History of +British Birds,' vol. ii. p. 354. On the Indian Bustard, Jerdon, 'Birds of +India,' vol. iii. p. 618.) + +[Fig. 46. Bower-bird, Chlamydera maculata, with bower (from Brehm).] + +But the most curious case is afforded by three allied genera of Australian +birds, the famous Bower-birds,--no doubt the co-descendants of some ancient +species which first acquired the strange instinct of constructing bowers +for performing their love-antics. The bowers (Fig. 46), which, as we shall +hereafter see, are decorated with feathers, shells, bones, and leaves, are +built on the ground for the sole purpose of courtship, for their nests are +formed in trees. Both sexes assist in the erection of the bowers, but the +male is the principal workman. So strong is this instinct that it is +practised under confinement, and Mr. Strange has described (60. Gould, +'Handbook to the Birds of Australia,' vol. i. pp. 444, 449, 455. The bower +of the Satin Bower-bird may be seen in the Zoological Society's Gardens, +Regent's Park.) the habits of some Satin Bower-birds which he kept in an +aviary in New South Wales. "At times the male will chase the female all +over the aviary, then go to the bower, pick up a gay feather or a large +leaf, utter a curious kind of note, set all his feathers erect, run round +the bower and become so excited that his eyes appear ready to start from +his bead; he continues opening first one wing then the other, uttering a +low, whistling note, and, like the domestic cock, seems to be picking up +something from the ground, until at last the female goes gently towards +him." Captain Stokes has described the habits and "play-houses" of another +species, the Great Bower-bird, which was seen "amusing itself by flying +backwards and forwards, taking a shell alternately from each side, and +carrying it through the archway in its mouth." These curious structures, +formed solely as halls of assemblage, where both sexes amuse themselves and +pay their court, must cost the birds much labour. The bower, for instance, +of the Fawn-breasted species, is nearly four feet in length, eighteen +inches in height, and is raised on a thick platform of sticks. + +DECORATION. + +I will first discuss the cases in which the males are ornamented either +exclusively or in a much higher degree than the females, and in a +succeeding chapter those in which both sexes are equally ornamented, and +finally the rare cases in which the female is somewhat more brightly- +coloured than the male. As with the artificial ornaments used by savage +and civilised men, so with the natural ornaments of birds, the head is the +chief seat of decoration. (61. See remarks to this effect, on the +'Feeling of Beauty among Animals,' by Mr. J. Shaw, in the 'Athenaeum,' Nov. +24th, 1866, p. 681.) The ornaments, as mentioned at the commencement of +this chapter, are wonderfully diversified. The plumes on the front or back +of the head consist of variously-shaped feathers, sometimes capable of +erection or expansion, by which their beautiful colours are fully +displayed. Elegant ear-tufts (Fig. 39) are occasionally present. The head +is sometimes covered with velvety down, as with the pheasant; or is naked +and vividly coloured. The throat, also, is sometimes ornamented with a +beard, wattles, or caruncles. Such appendages are generally brightly- +coloured, and no doubt serve as ornaments, though not always ornamental in +our eyes; for whilst the male is in the act of courting the female, they +often swell and assume vivid tints, as in the male turkey. At such times +the fleshy appendages about the head of the male Tragopan pheasant +(Ceriornis Temminckii) swell into a large lappet on the throat and into two +horns, one on each side of the splendid top-knot; and these are then +coloured of the most intense blue which I have ever beheld. (62. See Dr. +Murie's account with coloured figures in 'Proceedings, Zoological Society,' +1872, p. 730.) The African hornbill (Bucorax abyssinicus) inflates the +scarlet bladder-like wattle on its neck, and with its wings drooping and +tail expanded "makes quite a grand appearance." (63. Mr. Monteiro, +'Ibis,' vol. iv. 1862, p. 339.) Even the iris of the eye is sometimes more +brightly-coloured in the male than in the female; and this is frequently +the case with the beak, for instance, in our common blackbird. In Buceros +corrugatus, the whole beak and immense casque are coloured more +conspicuously in the male than in the female; and "the oblique grooves upon +the sides of the lower mandible are peculiar to the male sex." (64. 'Land +and Water,' 1868, p. 217.) + +The head, again, often supports fleshy appendages, filaments, and solid +protuberances. These, if not common to both sexes, are always confined to +the males. The solid protuberances have been described in detail by Dr. W. +Marshall (65. 'Ueber die Schädelhöcker,' etc., 'Niederland. Archiv. fur +Zoologie,' B. I. Heft 2, 1872.), who shews that they are formed either of +cancellated bone coated with skin, or of dermal and other tissues. With +mammals true horns are always supported on the frontal bones, but with +birds various bones have been modified for this purpose; and in species of +the same group the protuberances may have cores of bone, or be quite +destitute of them, with intermediate gradations connecting these two +extremes. Hence, as Dr. Marshall justly remarks, variations of the most +different kinds have served for the development through sexual selection of +these ornamental appendages. Elongated feathers or plumes spring from +almost every part of the body. The feathers on the throat and breast are +sometimes developed into beautiful ruffs and collars. The tail-feathers +are frequently increased in length; as we see in the tail-coverts of the +peacock, and in the tail itself of the Argus pheasant. With the peacock +even the bones of the tail have been modified to support the heavy tail- +coverts. (66. Dr. W. Marshall, 'Über den Vogelschwanz,' ibid. B. I. Heft +2, 1872.) The body of the Argus is not larger than that of a fowl; yet the +length from the end of the beak to the extremity of the tail is no less +than five feet three inches (67. Jardine's 'Naturalist Library: Birds,' +vol. xiv. p. 166.), and that of the beautifully ocellated secondary wing- +feathers nearly three feet. In a small African night-jar (Cosmetornis +vexillarius) one of the primary wing-feathers, during the breeding-season, +attains a length of twenty-six inches, whilst the bird itself is only ten +inches in length. In another closely-allied genus of night-jars, the +shafts of the elongated wing-feathers are naked, except at the extremity, +where there is a disc. (68. Sclater, in the 'Ibis,' vol. vi. 1864, p. +114; Livingstone, 'Expedition to the Zambesi,' 1865, p. 66.) Again, in +another genus of night-jars, the tail-feathers are even still more +prodigiously developed. In general the feathers of the tail are more often +elongated than those of the wings, as any great elongation of the latter +impedes flight. We thus see that in closely-allied birds ornaments of the +same kind have been gained by the males through the development of widely +different feathers. + +It is a curious fact that the feathers of species belonging to very +distinct groups have been modified in almost exactly the same peculiar +manner. Thus the wing-feathers in one of the above-mentioned night-jars +are bare along the shaft, and terminate in a disc; or are, as they are +sometimes called, spoon or racket-shaped. Feathers of this kind occur in +the tail of a motmot (Eumomota superciliaris), of a king-fisher, finch, +humming-bird, parrot, several Indian drongos (Dicrurus and Edolius, in one +of which the disc stands vertically), and in the tail of certain birds of +paradise. In these latter birds, similar feathers, beautifully ocellated, +ornament the head, as is likewise the case with some gallinaceous birds. +In an Indian bustard (Sypheotides auritus) the feathers forming the ear- +tufts, which are about four inches in length, also terminate in discs. +(69. Jerdon, 'Birds of India,' vol. iii. p. 620.) It is a most singular +fact that the motmots, as Mr. Salvin has clearly shewn (70. 'Proceedings, +Zoological Society,' 1873, p. 429.), give to their tail feathers the +racket-shape by biting off the barbs, and, further, that this continued +mutilation has produced a certain amount of inherited effect. + +[Fig. 47. Paradisea Papuana (T.W. Wood).] + +Again, the barbs of the feathers in various widely-distinct birds are +filamentous or plumose, as with some herons, ibises, birds of paradise, and +Gallinaceae. In other cases the barbs disappear, leaving the shafts bare +from end to end; and these in the tail of the Paradisea apoda attain a +length of thirty-four inches (71. Wallace, in 'Annals and Magazine of +Natural History,' vol. xx. 1857, p. 416, and in his 'Malay Archipelago,' +vol. ii. 1869, p. 390.): in P. Papuana (Fig. 47) they are much shorter and +thin. Smaller feathers when thus denuded appear like bristles, as on the +breast of the turkey-cock. As any fleeting fashion in dress comes to be +admired by man, so with birds a change of almost any kind in the structure +or colouring of the feathers in the male appears to have been admired by +the female. The fact of the feathers in widely distinct groups having been +modified in an analogous manner no doubt depends primarily on all the +feathers having nearly the same structure and manner of development, and +consequently tending to vary in the same manner. We often see a tendency +to analogous variability in the plumage of our domestic breeds belonging to +distinct species. Thus top-knots have appeared in several species. In an +extinct variety of the turkey, the top-knot consisted of bare quills +surmounted with plumes of down, so that they somewhat resembled the racket- +shaped feathers above described. In certain breeds of the pigeon and fowl +the feathers are plumose, with some tendency in the shafts to be naked. In +the Sebastopol goose the scapular feathers are greatly elongated, curled, +or even spirally twisted, with the margins plumose. (72. See my work on +'The Variation of Animals and Plants under Domestication,' vol. i. pp. 289, +293.) + +In regard to colour, hardly anything need here be said, for every one knows +how splendid are the tints of many birds, and how harmoniously they are +combined. The colours are often metallic and iridescent. Circular spots +are sometimes surrounded by one or more differently shaded zones, and are +thus converted into ocelli. Nor need much be said on the wonderful +difference between the sexes of many birds. The common peacock offers a +striking instance. Female birds of paradise are obscurely coloured and +destitute of all ornaments, whilst the males are probably the most highly +decorated of all birds, and in so many different ways that they must be +seen to be appreciated. The elongated and golden-orange plumes which +spring from beneath the wings of the Paradisea apoda, when vertically +erected and made to vibrate, are described as forming a sort of halo, in +the centre of which the head "looks like a little emerald sun with its rays +formed by the two plumes." (73. Quoted from M. de Lafresnaye in 'Annals +and Mag. of Natural History,' vol. xiii. 1854, p. 157: see also Mr. +Wallace's much fuller account in vol. xx. 1857, p. 412, and in his 'Malay +Archipelago.'S) In another most beautiful species the head is bald, "and +of a rich cobalt blue, crossed by several lines of black velvety feathers." +(74. Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 405.) + +[Fig. 48. Lophornis ornatus, male and female (from Brehm). + +Fig. 49. Spathura underwoodi, male and female (from Brehm).] + +Male humming-birds (Figs. 48 and 49) almost vie with birds of paradise in +their beauty, as every one will admit who has seen Mr. Gould's splendid +volumes, or his rich collection. It is very remarkable in how many +different ways these birds are ornamented. Almost every part of their +plumage has been taken advantage of, and modified; and the modifications +have been carried, as Mr. Gould shewed me, to a wonderful extreme in some +species belonging to nearly every sub-group. Such cases are curiously like +those which we see in our fancy breeds, reared by man for the sake of +ornament; certain individuals originally varied in one character, and other +individuals of the same species in other characters; and these have been +seized on by man and much augmented--as shewn by the tail of the fantail- +pigeon, the hood of the jacobin, the beak and wattle of the carrier, and so +forth. The sole difference between these cases is that in the one, the +result is due to man's selection, whilst in the other, as with humming- +birds, birds of paradise, etc., it is due to the selection by the females +of the more beautiful males. + +I will mention only one other bird, remarkable from the extreme contrast in +colour between the sexes, namely the famous bell-bird (Chasmorhynchus +niveus) of S. America, the note of which can be distinguished at the +distance of nearly three miles, and astonishes every one when first hearing +it. The male is pure white, whilst the female is dusky-green; and white is +a very rare colour in terrestrial species of moderate size and inoffensive +habits. The male, also, as described by Waterton, has a spiral tube, +nearly three inches in length, which rises from the base of the beak. It +is jet-black, dotted over with minute downy feathers. This tube can be +inflated with air, through a communication with the palate; and when not +inflated hangs down on one side. The genus consists of four species, the +males of which are very distinct, whilst the females, as described by Mr. +Sclater in a very interesting paper, closely resemble each other, thus +offering an excellent instance of the common rule that within the same +group the males differ much more from each other than do the females. In a +second species (C. nudicollis) the male is likewise snow-white, with the +exception of a large space of naked skin on the throat and round the eyes, +which during the breeding-season is of a fine green colour. In a third +species (C. tricarunculatus) the head and neck alone of the male are white, +the rest of the body being chestnut-brown, and the male of this species is +provided with three filamentous projections half as long as the body--one +rising from the base of the beak, and the two others from the corners of +the mouth. (75. Mr. Sclater, 'Intellectual Observer,' Jan. 1867. +Waterton's 'Wanderings,' p. 118. See also Mr. Salvin's interesting paper, +with a plate, in the 'Ibis,' 1865, p. 90.) + +The coloured plumage and certain other ornaments of the adult males are +either retained for life, or are periodically renewed during the summer and +breeding-season. At this same season the beak and naked skin about the +head frequently change colour, as with some herons, ibises, gulls, one of +the bell-birds just noticed, etc. In the white ibis, the cheeks, the +inflatable skin of the throat, and the basal portion of the beak then +become crimson. (76. 'Land and Water,' 1867, p. 394.) In one of the +rails, Gallicrex cristatus, a large red caruncle is developed during this +period on the head of the male. So it is with a thin horny crest on the +beak of one of the pelicans, P. erythrorhynchus; for, after the breeding- +season, these horny crests are shed, like horns from the heads of stags, +and the shore of an island in a lake in Nevada was found covered with these +curious exuviae. (77. Mr. D.G. Elliot, in 'Proc. Zool. Soc.' 1869, p. +589.) + +Changes of colour in the plumage according to the season depend, firstly on +a double annual moult, secondly on an actual change of colour in the +feathers themselves, and thirdly on their dull-coloured margins being +periodically shed, or on these three processes more or less combined. The +shedding of the deciduary margins may be compared with the shedding of +their down by very young birds; for the down in most cases arises from the +summits of the first true feathers. (78. Nitzsch's 'Pterylography,' +edited by P.L. Sclater, Ray Society, 1867, p. 14.) + +With respect to the birds which annually undergo a double moult, there are, +firstly, some kinds, for instance snipes, swallow-plovers (Glareolae), and +curlews, in which the two sexes resemble each other, and do not change +colour at any season. I do not know whether the winter plumage is thicker +and warmer than the summer plumage, but warmth seems the most probable end +attained of a double moult, where there is no change of colour. Secondly, +there are birds, for instance, certain species of Totanus and other +Grallatores, the sexes of which resemble each other, but in which the +summer and winter plumage differ slightly in colour. The difference, +however, in these cases is so small that it can hardly be an advantage to +them; and it may, perhaps, be attributed to the direct action of the +different conditions to which the birds are exposed during the two seasons. +Thirdly, there are many other birds the sexes of which are alike, but which +are widely different in their summer and winter plumage. Fourthly, there +are birds the sexes of which differ from each other in colour; but the +females, though moulting twice, retain the same colours throughout the +year, whilst the males undergo a change of colour, sometimes a great one, +as with certain bustards. Fifthly and lastly, there are birds the sexes of +which differ from each other in both their summer and winter plumage; but +the male undergoes a greater amount of change at each recurrent season than +the female--of which the ruff (Machetes pugnax) offers a good instance. + +With respect to the cause or purpose of the differences in colour between +the summer and winter plumage, this may in some instances, as with the +ptarmigan (79. The brown mottled summer plumage of the ptarmigan is of as +much importance to it, as a protection, as the white winter plumage; for in +Scandinavia during the spring, when the snow has disappeared, this bird is +known to suffer greatly from birds of prey, before it has acquired its +summer dress: see Wilhelm von Wright, in Lloyd, 'Game Birds of Sweden,' +1867, p. 125.), serve during both seasons as a protection. When the +difference between the two plumages is slight it may perhaps be attributed, +as already remarked, to the direct action of the conditions of life. But +with many birds there can hardly be a doubt that the summer plumage is +ornamental, even when both sexes are alike. We may conclude that this is +the case with many herons, egrets, etc., for they acquire their beautiful +plumes only during the breeding-season. Moreover, such plumes, top-knots, +etc., though possessed by both sexes, are occasionally a little more +developed in the male than in the female; and they resemble the plumes and +ornaments possessed by the males alone of other birds. It is also known +that confinement, by affecting the reproductive system of male birds, +frequently checks the development of their secondary sexual characters, but +has no immediate influence on any other characters; and I am informed by +Mr. Bartlett that eight or nine specimens of the Knot (Tringa canutus) +retained their unadorned winter plumage in the Zoological Gardens +throughout the year, from which fact we may infer that the summer plumage, +though common to both sexes, partakes of the nature of the exclusively +masculine plumage of many other birds. (80. In regard to the previous +statements on moulting, see, on snipes, etc., Macgillivray, 'Hist. Brit. +Birds,' vol. iv. p. 371; on Glareolae, curlews, and bustards, Jerdon, +'Birds of India,' vol. iii. pp. 615, 630, 683; on Totanus, ibid. p. 700; on +the plumes of herons, ibid. p. 738, and Macgillivray, vol. iv. pp. 435 and +444, and Mr. Stafford Allen, in the 'Ibis,' vol. v. 1863, p. 33.) + +From the foregoing facts, more especially from neither sex of certain birds +changing colour during either annual moult, or changing so slightly that +the change can hardly be of any service to them, and from the females of +other species moulting twice yet retaining the same colours throughout the +year, we may conclude that the habit of annually moulting twice has not +been acquired in order that the male should assume an ornamental character +during the breeding-season; but that the double moult, having been +originally acquired for some distinct purpose, has subsequently been taken +advantage of in certain cases for gaining a nuptial plumage. + +It appears at first sight a surprising circumstance that some closely- +allied species should regularly undergo a double annual moult, and others +only a single one. The ptarmigan, for instance, moults twice or even +thrice in the year, and the blackcock only once: some of the splendidly +coloured honey-suckers (Nectariniae) of India and some sub-genera of +obscurely coloured pipits (Anthus) have a double, whilst others have only a +single annual moult. (81. On the moulting of the ptarmigan, see Gould's +'Birds of Great Britain.' On the honey-suckers, Jerdon, 'Birds of India,' +vol. i. pp. 359, 365, 369. On the moulting of Anthus, see Blyth, in +'Ibis,' 1867, p. 32.) But the gradations in the manner of moulting, which +are known to occur with various birds, shew us how species, or whole +groups, might have originally acquired their double annual moult, or having +once gained the habit, have again lost it. With certain bustards and +plovers the vernal moult is far from complete, some feathers being renewed, +and some changed in colour. There is also reason to believe that with +certain bustards and rail-like birds, which properly undergo a double +moult, some of the older males retain their nuptial plumage throughout the +year. A few highly modified feathers may merely be added during the spring +to the plumage, as occurs with the disc-formed tail-feathers of certain +drongos (Bhringa) in India, and with the elongated feathers on the back, +neck, and crest of certain herons. By such steps as these, the vernal +moult might be rendered more and more complete, until a perfect double +moult was acquired. Some of the birds of paradise retain their nuptial +feathers throughout the year, and thus have only a single moult; others +cast them directly after the breeding-season, and thus have a double moult; +and others again cast them at this season during the first year, but not +afterwards; so that these latter species are intermediate in their manner +of moulting. There is also a great difference with many birds in the +length of time during which the two annual plumages are retained; so that +the one might come to be retained for the whole year, and the other +completely lost. Thus in the spring Machetes pugnax retains his ruff for +barely two months. In Natal the male widow-bird (Chera progne) acquires +his fine plumage and long tail-feathers in December or January, and loses +them in March; so that they are retained only for about three months. Most +species, which undergo a double moult, keep their ornamental feathers for +about six months. The male, however, of the wild Gallus bankiva retains +his neck-hackles for nine or ten months; and when these are cast off, the +underlying black feathers on the neck are fully exposed to view. But with +the domesticated descendant of this species, the neck-hackles of the male +are immediately replaced by new ones; so that we here see, as to part of +the plumage, a double moult changed under domestication into a single +moult. (82. For the foregoing statements in regard to partial moults, and +on old males retaining their nuptial plumage, see Jerdon, on bustards and +plovers, in 'Birds of India,' vol. iii. pp. 617, 637, 709, 711. Also Blyth +in 'Land and Water,' 1867, p. 84. On the moulting of Paradisea, see an +interesting article by Dr. W. Marshall, 'Archives Neerlandaises,' tom. vi. +1871. On the Vidua, 'Ibis,' vol. iii. 1861, p. 133. On the Drongo- +shrikes, Jerdon, ibid. vol. i. p. 435. On the vernal moult of the Herodias +bubulcus, Mr. S.S. Allen, in 'Ibis,' 1863, p. 33. On Gallus bankiva, +Blyth, in 'Annals and Mag. of Natural History,' vol. i. 1848, p. 455; see, +also, on this subject, my 'Variation of Animals under Domestication,' vol. +i. p. 236.) + +The common drake (Anas boschas), after the breeding-season, is well known +to lose his male plumage for a period of three months, during which time he +assumes that of the female. The male pin-tail duck (Anas acuta) loses his +plumage for the shorter period of six weeks or two months; and Montagu +remarks that "this double moult within so short a time is a most +extraordinary circumstance, that seems to bid defiance to all human +reasoning." But the believer in the gradual modification of species will +be far from feeling surprise at finding gradations of all kinds. If the +male pin-tail were to acquire his new plumage within a still shorter +period, the new male feathers would almost necessarily be mingled with the +old, and both with some proper to the female; and this apparently is the +case with the male of a not distantly-allied bird, namely the Merganser +serrator, for the males are said to "undergo a change of plumage, which +assimilates them in some measure to the female." By a little further +acceleration in the process, the double moult would be completely lost. +(83. See Macgillivray, 'Hist. British Birds' (vol. v. pp. 34, 70, and +223), on the moulting of the Anatidae, with quotations from Waterton and +Montagu. Also Yarrell, 'History of British Birds,' vol. iii. p. 243.) + +Some male birds, as before stated, become more brightly coloured in the +spring, not by a vernal moult, but either by an actual change of colour in +the feathers, or by their obscurely-coloured deciduary margins being shed. +Changes of colour thus caused may last for a longer or shorter time. In +the Pelecanus onocrotalus a beautiful rosy tint, with lemon-coloured marks +on the breast, overspreads the whole plumage in the spring; but these +tints, as Mr. Sclater states, "do not last long, disappearing generally in +about six weeks or two months after they have been attained." Certain +finches shed the margins of their feathers in the spring, and then become +brighter coloured, while other finches undergo no such change. Thus the +Fringilla tristis of the United States (as well as many other American +species) exhibits its bright colours only when the winter is past, whilst +our goldfinch, which exactly represents this bird in habits, and our +siskin, which represents it still more closely in structure, undergo no +such annual change. But a difference of this kind in the plumage of allied +species is not surprising, for with the common linnet, which belongs to the +same family, the crimson forehead and breast are displayed only during the +summer in England, whilst in Madeira these colours are retained throughout +the year. (84. On the pelican, see Sclater, in 'Proc. Zool. Soc.' 1868, +p. 265. On the American finches, see Audubon, 'Ornithological Biography,' +vol. i. pp. 174, 221, and Jerdon, 'Birds of India,' vol. ii. p. 383. On +the Fringilla cannabina of Madeira, Mr. E. Vernon Harcourt, 'Ibis,' vol. v. +1863, p. 230.) + +DISPLAY BY MALE BIRDS OF THEIR PLUMAGE. + +Ornaments of all kinds, whether permanently or temporarily gained, are +sedulously displayed by the males, and apparently serve to excite, attract, +or fascinate the females. But the males will sometimes display their +ornaments, when not in the presence of the females, as occasionally occurs +with grouse at their balz-places, and as may be noticed with the peacock; +this latter bird, however, evidently wishes for a spectator of some kind, +and, as I have often seen, will shew off his finery before poultry, or even +pigs. (85. See also 'Ornamental Poultry,' by Rev. E.S. Dixon, 1848, p. +8.) All naturalists who have closely attended to the habits of birds, +whether in a state of nature or under confinement, are unanimously of +opinion that the males take delight in displaying their beauty. Audubon +frequently speaks of the male as endeavouring in various ways to charm the +female. Mr. Gould, after describing some peculiarities in a male humming- +bird, says he has no doubt that it has the power of displaying them to the +greatest advantage before the female. Dr. Jerdon (86. 'Birds of India,' +introduct., vol. i. p. xxiv.; on the peacock, vol. iii. p. 507. See +Gould's 'Introduction to Trochilidae,' 1861, pp. 15 and 111.) insists that +the beautiful plumage of the male serves "to fascinate and attract the +female." Mr. Bartlett, at the Zoological Gardens, expressed himself to me +in the strongest terms to the same effect. + +[Fig. 50. Rupicola crocea, male (T.W. Wood).] + +It must be a grand sight in the forests of India "to come suddenly on +twenty or thirty pea-fowl, the males displaying their gorgeous trains, and +strutting about in all the pomp of pride before the gratified females." +The wild turkey-cock erects his glittering plumage, expands his finely- +zoned tail and barred wing-feathers, and altogether, with his crimson and +blue wattles, makes a superb, though, to our eyes, grotesque appearance. +Similar facts have already been given with respect to grouse of various +kinds. Turning to another Order: The male Rupicola crocea (Fig. 50) is +one of the most beautiful birds in the world, being of a splendid orange, +with some of the feathers curiously truncated and plumose. The female is +brownish-green, shaded with red, and has a much smaller crest. Sir R. +Schomburgk has described their courtship; he found one of their meeting- +places where ten males and two females were present. The space was from +four to five feet in diameter, and appeared to have been cleared of every +blade of grass and smoothed as if by human hands. A male "was capering, to +the apparent delight of several others. Now spreading its wings, throwing +up its head, or opening its tail like a fan; now strutting about with a +hopping gait until tired, when it gabbled some kind of note, and was +relieved by another. Thus three of them successively took the field, and +then, with self-approbation, withdrew to rest." The Indians, in order to +obtain their skins, wait at one of the meeting-places till the birds are +eagerly engaged in dancing, and then are able to kill with their poisoned +arrows four or five males, one after the other. (87. 'Journal of R. +Geograph. Soc.' vol. x. 1840, p. 236.) With birds of paradise a dozen or +more full-plumaged males congregate in a tree to hold a dancing-party, as +it is called by the natives: and here they fly about, raise their wings, +elevate their exquisite plumes, and make them vibrate, and the whole tree +seems, as Mr. Wallace remarks, to be filled with waving plumes. When thus +engaged, they become so absorbed that a skilful archer may shoot nearly the +whole party. These birds, when kept in confinement in the Malay +Archipelago, are said to take much care in keeping their feathers clean; +often spreading them out, examining them, and removing every speck of dirt. +One observer, who kept several pairs alive, did not doubt that the display +of the male was intended to please the female. (88. 'Annals and Mag. of +Nat. Hist.' vol. xiii. 1854, p. 157; also Wallace, ibid. vol. xx. 1857, p. +412, and 'The Malay Archipelago,' vol. ii. 1869, p. 252. Also Dr. Bennett, +as quoted by Brehm, 'Thierleben,' B. iii. s. 326.) + +[Fig. 51. Polyplectron chinquis, male (T.W. Wood).] + +The Gold and Amherst pheasants during their courtship not only expand and +raise their splendid frills, but twist them, as I have myself seen, +obliquely towards the female on whichever side she may be standing, +obviously in order that a large surface may be displayed before her. (89. +Mr. T.W. Wood has given ('The Student,' April 1870, p. 115) a full account +of this manner of display, by the Gold pheasant and by the Japanese +pheasant, Ph. versicolor; and he calls it the lateral or one-sided +display.) They likewise turn their beautiful tails and tail-coverts a +little towards the same side. Mr. Bartlett has observed a male +Polyplectron (Fig. 51) in the act of courtship, and has shewn me a specimen +stuffed in the attitude then assumed. The tail and wing-feathers of this +bird are ornamented with beautiful ocelli, like those on the peacock's +train. Now when the peacock displays himself, he expands and erects his +tail transversely to his body, for he stands in front of the female, and +has to shew off, at the same time, his rich blue throat and breast. But +the breast of the Polyplectron is obscurely coloured, and the ocelli are +not confined to the tail-feathers. Consequently the Polyplectron does not +stand in front of the female; but he erects and expands his tail-feathers a +little obliquely, lowering the expanded wing on the same side, and raising +that on the opposite side. In this attitude the ocelli over the whole body +are exposed at the same time before the eyes of the admiring female in one +grand bespangled expanse. To whichever side she may turn, the expanded +wings and the obliquely-held tail are turned towards her. The male +Tragopan pheasant acts in nearly the same manner, for he raises the +feathers of the body, though not the wing itself, on the side which is +opposite to the female, and which would otherwise be concealed, so that +nearly all the beautifully spotted feathers are exhibited at the same time. + +[Fig. 52. Side view of male Argus pheasant, whilst displaying before the +female. Observed and sketched from nature by T.W. Wood.] + +The Argus pheasant affords a much more remarkable case. The immensely +developed secondary wing-feathers are confined to the male; and each is +ornamented with a row of from twenty to twenty-three ocelli, above an inch +in diameter. These feathers are also elegantly marked with oblique stripes +and rows of spots of a dark colour, like those on the skin of a tiger and +leopard combined. These beautiful ornaments are hidden until the male +shows himself off before the female. He then erects his tail, and expands +his wing-feathers into a great, almost upright, circular fan or shield, +which is carried in front of the body. The neck and head are held on one +side, so that they are concealed by the fan; but the bird in order to see +the female, before whom he is displaying himself, sometimes pushes his head +between two of the long wing-feathers (as Mr. Bartlett has seen), and then +presents a grotesque appearance. This must be a frequent habit with the +bird in a state of nature, for Mr. Bartlett and his son on examining some +perfect skins sent from the East, found a place between two of the feathers +which was much frayed, as if the head had here frequently been pushed +through. Mr. Wood thinks that the male can also peep at the female on one +side, beyond the margin of the fan. + +The ocelli on the wing-feathers are wonderful objects; for they are so +shaded that, as the Duke of Argyll remarks (90. 'The Reign of Law,' 1867, +p. 203.), they stand out like balls lying loosely within sockets. When I +looked at the specimen in the British Museum, which is mounted with the +wings expanded and trailing downwards, I was however greatly disappointed, +for the ocelli appeared flat, or even concave. But Mr. Gould soon made the +case clear to me, for he held the feathers erect, in the position in which +they would naturally be displayed, and now, from the light shining on them +from above, each ocellus at once resembled the ornament called a ball and +socket. These feathers have been shown to several artists, and all have +expressed their admiration at the perfect shading. It may well be asked, +could such artistically shaded ornaments have been formed by means of +sexual selection? But it will be convenient to defer giving an answer to +this question until we treat in the next chapter of the principle of +gradation. + +The foregoing remarks relate to the secondary wing-feathers, but the +primary wing-feathers, which in most gallinaceous birds are uniformly +coloured, are in the Argus pheasant equally wonderful. They are of a soft +brown tint with numerous dark spots, each of which consists of two or three +black dots with a surrounding dark zone. But the chief ornament is a space +parallel to the dark-blue shaft, which in outline forms a perfect second +feather lying within the true feather. This inner part is coloured of a +lighter chestnut, and is thickly dotted with minute white points. I have +shewn this feather to several persons, and many have admired it even more +than the ball and socket feathers, and have declared that it was more like +a work of art than of nature. Now these feathers are quite hidden on all +ordinary occasions, but are fully displayed, together with the long +secondary feathers, when they are all expanded together so as to form the +great fan or shield. + +The case of the male Argus pheasant is eminently interesting, because it +affords good evidence that the most refined beauty may serve as a sexual +charm, and for no other purpose. We must conclude that this is the case, +as the secondary and primary wing-feathers are not at all displayed, and +the ball and socket ornaments are not exhibited in full perfection until +the male assumes the attitude of courtship. The Argus pheasant does not +possess brilliant colours, so that his success in love appears to depend on +the great size of his plumes, and on the elaboration of the most elegant +patterns. Many will declare that it is utterly incredible that a female +bird should be able to appreciate fine shading and exquisite patterns. It +is undoubtedly a marvellous fact that she should possess this almost human +degree of taste. He who thinks that he can safely gauge the discrimination +and taste of the lower animals may deny that the female Argus pheasant can +appreciate such refined beauty; but he will then be compelled to admit that +the extraordinary attitudes assumed by the male during the act of +courtship, by which the wonderful beauty of his plumage is fully displayed, +are purposeless; and this is a conclusion which I for one will never admit. + +Although so many pheasants and allied gallinaceous birds carefully display +their plumage before the females, it is remarkable, as Mr. Bartlett informs +me, that this is not the case with the dull-coloured Eared and Cheer +pheasants (Crossoptilon auritum and Phasianus wallichii); so that these +birds seem conscious that they have little beauty to display. Mr. Bartlett +has never seen the males of either of these species fighting together, +though he has not had such good opportunities for observing the Cheer as +the Eared pheasant. Mr. Jenner Weir, also, finds that all male birds with +rich or strongly-characterised plumage are more quarrelsome than the dull- +coloured species belonging to the same groups. The goldfinch, for +instance, is far more pugnacious than the linnet, and the blackbird than +the thrush. Those birds which undergo a seasonal change of plumage +likewise become much more pugnacious at the period when they are most gaily +ornamented. No doubt the males of some obscurely-coloured birds fight +desperately together, but it appears that when sexual selection has been +highly influential, and has given bright colours to the males of any +species, it has also very often given a strong tendency to pugnacity. We +shall meet with nearly analogous cases when we treat of mammals. On the +other hand, with birds the power of song and brilliant colours have rarely +been both acquired by the males of the same species; but in this case the +advantage gained would have been the same, namely success in charming the +female. Nevertheless it must be owned that the males of several +brilliantly coloured birds have had their feathers specially modified for +the sake of producing instrumental music, though the beauty of this cannot +be compared, at least according to our taste, with that of the vocal music +of many songsters. + +We will now turn to male birds which are not ornamented in any high degree, +but which nevertheless display during their courtship whatever attractions +they may possess. These cases are in some respects more curious than the +foregoing, and have been but little noticed. I owe the following facts to +Mr. Weir, who has long kept confined birds of many kinds, including all the +British Fringillidae and Emberizidae. The facts have been selected from a +large body of valuable notes kindly sent me by him. The bullfinch makes +his advances in front of the female, and then puffs out his breast, so that +many more of the crimson feathers are seen at once than otherwise would be +the case. At the same time he twists and bows his black tail from side to +side in a ludicrous manner. The male chaffinch also stands in front of the +female, thus shewing his red breast and "blue bell," as the fanciers call +his head; the wings at the same time being slightly expanded, with the pure +white bands on the shoulders thus rendered conspicuous. The common linnet +distends his rosy breast, slightly expands his brown wings and tail, so as +to make the best of them by exhibiting their white edgings. We must, +however, be cautious in concluding that the wings are spread out solely for +display, as some birds do so whose wings are not beautiful. This is the +case with the domestic cock, but it is always the wing on the side opposite +to the female which is expanded, and at the same time scraped on the +ground. The male goldfinch behaves differently from all other finches: +his wings are beautiful, the shoulders being black, with the dark-tipped +wing-feathers spotted with white and edged with golden yellow. When he +courts the female, he sways his body from side to side, and quickly turns +his slightly expanded wings first to one side, then to the other, with a +golden flashing effect. Mr. Weir informs me that no other British finch +turns thus from side to side during his courtship, not even the closely- +allied male siskin, for he would not thus add to his beauty. + +Most of the British Buntings are plain coloured birds; but in the spring +the feathers on the head of the male reed-bunting (Emberiza schoeniculus) +acquire a fine black colour by the abrasion of the dusky tips; and these +are erected during the act of courtship. Mr. Weir has kept two species of +Amadina from Australia: the A. castanotis is a very small and chastely +coloured finch, with a dark tail, white rump, and jet-black upper tail- +coverts, each of the latter being marked with three large conspicuous oval +spots of white. (91. For the description of these birds, see Gould's +'Handbook to the Birds of Australia,' vol. i. 1865, p. 417.) This species, +when courting the female, slightly spreads out and vibrates these parti- +coloured tail-coverts in a very peculiar manner. The male Amadina Lathami +behaves very differently, exhibiting before the female his brilliantly +spotted breast, scarlet rump, and scarlet upper tail-coverts. I may here +add from Dr. Jerdon that the Indian bulbul (Pycnonotus hoemorrhous) has its +under tail-coverts of a crimson colour, and these, it might be thought, +could never be well exhibited; but the bird "when excited often spreads +them out laterally, so that they can be seen even from above." (92. +'Birds of India,' vol. ii. p. 96.) The crimson under tail-coverts of some +other birds, as with one of the woodpeckers, Picus major, can be seen +without any such display. The common pigeon has iridescent feathers on the +breast, and every one must have seen how the male inflates his breast +whilst courting the female, thus shewing them off to the best advantage. +One of the beautiful bronze-winged pigeons of Australia (Ocyphaps lophotes) +behaves, as described to me by Mr. Weir, very differently: the male, +whilst standing before the female, lowers his head almost to the ground, +spreads out and raises his tail, and half expands his wings. He then +alternately and slowly raises and depresses his body, so that the +iridescent metallic feathers are all seen at once, and glitter in the sun. + +Sufficient facts have now been given to shew with what care male birds +display their various charms, and this they do with the utmost skill. +Whilst preening their feathers, they have frequent opportunities for +admiring themselves, and of studying how best to exhibit their beauty. But +as all the males of the same species display themselves in exactly the same +manner, it appears that actions, at first perhaps intentional, have become +instinctive. If so, we ought not to accuse birds of conscious vanity; yet +when we see a peacock strutting about, with expanded and quivering tail- +feathers, he seems the very emblem of pride and vanity. + +The various ornaments possessed by the males are certainly of the highest +importance to them, for in some cases they have been acquired at the +expense of greatly impeded powers of flight or of running. The African +night-jar (Cosmetornis), which during the pairing-season has one of its +primary wing-feathers developed into a streamer of very great length, is +thereby much retarded in its flight, although at other times remarkable for +its swiftness. The "unwieldy size" of the secondary wing-feathers of the +male Argus pheasant is said "almost entirely to deprive the bird of +flight." The fine plumes of male birds of paradise trouble them during a +high wind. The extremely long tail-feathers of the male widow-birds +(Vidua) of Southern Africa render "their flight heavy;" but as soon as +these are cast off they fly as well as the females. As birds always breed +when food is abundant, the males probably do not suffer much inconvenience +in searching for food from their impeded powers of movement; but there can +hardly be a doubt that they must be much more liable to be struck down by +birds of prey. Nor can we doubt that the long train of the peacock and the +long tail and wing-feathers of the Argus pheasant must render them an +easier prey to any prowling tiger-cat than would otherwise be the case. +Even the bright colours of many male birds cannot fail to make them +conspicuous to their enemies of all kinds. Hence, as Mr. Gould has +remarked, it probably is that such birds are generally of a shy +disposition, as if conscious that their beauty was a source of danger, and +are much more difficult to discover or approach, than the sombre coloured +and comparatively tame females or than the young and as yet unadorned +males. (93. On the Cosmetornis, see Livingstone's 'Expedition to the +Zambesi,' 1865, p. 66. On the Argus pheasant, Jardine's 'Nat. Hist. Lib.: +Birds,' vol. xiv. p. 167. On Birds of Paradise, Lesson, quoted by Brehm, +'Thierleben,' B. iii. s. 325. On the widow-bird, Barrow's 'Travels in +Africa,' vol. i. p. 243, and 'Ibis,' vol. iii. 1861 p. 133. Mr. Gould, on +the shyness of male birds, 'Handbook to Birds of Australia,' vol. i. 1865, +pp. 210, 457.) + +It is a more curious fact that the males of some birds which are provided +with special weapons for battle, and which in a state of nature are so +pugnacious that they often kill each other, suffer from possessing certain +ornaments. Cock-fighters trim the hackles and cut off the combs and gills +of their cocks; and the birds are then said to be dubbed. An undubbed +bird, as Mr. Tegetmeier insists, "is at a fearful disadvantage; the comb +and gills offer an easy hold to his adversary's beak, and as a cock always +strikes where he holds, when once he has seized his foe, he has him +entirely in his power. Even supposing that the bird is not killed, the +loss of blood suffered by an undubbed cock is much greater than that +sustained by one that has been trimmed." (94. Tegetmeier, 'The Poultry +Book,' 1866, p. 139.) Young turkey-cocks in fighting always seize hold of +each other's wattles; and I presume that the old birds fight in the same +manner. It may perhaps be objected that the comb and wattles are not +ornamental, and cannot be of service to the birds in this way; but even to +our eyes, the beauty of the glossy black Spanish cock is much enhanced by +his white face and crimson comb; and no one who has ever seen the splendid +blue wattles of the male Tragopan pheasant distended in courtship can for a +moment doubt that beauty is the object gained. From the foregoing facts we +clearly see that the plumes and other ornaments of the males must be of the +highest importance to them; and we further see that beauty is even +sometimes more important than success in battle. + + +CHAPTER XIV. + +BIRDS--continued. + +Choice exerted by the female--Length of courtship--Unpaired birds--Mental +qualities and taste for the beautiful--Preference or antipathy shewn by the +female for particular males--Variability of birds--Variations sometimes +abrupt--Laws of variation--Formation of ocelli--Gradations of character-- +Case of Peacock, Argus pheasant, and Urosticte. + +When the sexes differ in beauty or in the power of singing, or in producing +what I have called instrumental music, it is almost invariably the male who +surpasses the female. These qualities, as we have just seen, are evidently +of high importance to the male. When they are gained for only a part of +the year it is always before the breeding-season. It is the male alone who +elaborately displays his varied attractions, and often performs strange +antics on the ground or in the air, in the presence of the female. Each +male drives away, or if he can, kills his rivals. Hence we may conclude +that it is the object of the male to induce the female to pair with him, +and for this purpose he tries to excite or charm her in various ways; and +this is the opinion of all those who have carefully studied the habits of +living birds. But there remains a question which has an all important +bearing on sexual selection, namely, does every male of the same species +excite and attract the female equally? Or does she exert a choice, and +prefer certain males? This latter question can be answered in the +affirmative by much direct and indirect evidence. It is far more difficult +to decide what qualities determine the choice of the females; but here +again we have some direct and indirect evidence that it is to a large +extent the external attractions of the male; though no doubt his vigour, +courage, and other mental qualities come into play. We will begin with the +indirect evidence. + +LENGTH OF COURTSHIP. + +The lengthened period during which both sexes of certain birds meet day +after day at an appointed place probably depends partly on the courtship +being a prolonged affair, and partly on reiteration in the act of pairing. +Thus in Germany and Scandinavia the balzen or leks of the black-cocks last +from the middle of March, all through April into May. As many as forty or +fifty, or even more birds congregate at the leks; and the same place is +often frequented during successive years. The lek of the capercailzie +lasts from the end of March to the middle or even end of May. In North +America "the partridge dances" of the Tetrao phasianellus "last for a month +or more." Other kinds of grouse, both in North America and Eastern Siberia +(1. Nordman describes ('Bull. Soc. Imp. des Nat. Moscou,' 1861, tom. +xxxiv. p. 264) the balzen of Tetrao urogalloides in Amur Land. He +estimated the number of birds assembled at above a hundred, not counting +the females, which lie hid in the surrounding bushes. The noises uttered +differ from those of T. urogallus.), follow nearly the same habits. The +fowlers discover the hillocks where the ruffs congregate by the grass being +trampled bare, and this shews that the same spot is long frequented. The +Indians of Guiana are well acquainted with the cleared arenas, where they +expect to find the beautiful cocks of the Rock; and the natives of New +Guinea know the trees where from ten to twenty male birds of paradise in +full plumage congregate. In this latter case it is not expressly stated +that the females meet on the same trees, but the hunters, if not specially +asked, would probably not mention their presence, as their skins are +valueless. Small parties of an African weaver (Ploceus) congregate, during +the breeding-season, and perform for hours their graceful evolutions. +Large numbers of the Solitary snipe (Scolopax major) assemble during dusk +in a morass; and the same place is frequented for the same purpose during +successive years; here they may be seen running about "like so many large +rats," puffing out their feathers, flapping their wings, and uttering the +strangest cries. (2. With respect to the assemblages of the above named +grouse, see Brehm, 'Thierleben,' B. iv. s. 350; also L. Lloyd, 'Game Birds +of Sweden,' 1867, pp. 19, 78. Richardson, 'Fauna Bor. Americana: Birds,' +p. 362. References in regard to the assemblages of other birds have +already been given. On Paradisea, see Wallace, in 'Annals and Mag. of Nat. +Hist.' vol. xx. 1857, p. 412. On the snipe, Lloyd, ibid. p. 221.) + +Some of the above birds,--the black-cock, capercailzie, pheasant-grouse, +ruff, solitary snipe, and perhaps others,--are, as is believed, +polygamists. With such birds it might have been thought that the stronger +males would simply have driven away the weaker, and then at once have taken +possession of as many females as possible; but if it be indispensable for +the male to excite or please the female, we can understand the length of +the courtship and the congregation of so many individuals of both sexes at +the same spot. Certain strictly monogamous species likewise hold nuptial +assemblages; this seems to be the case in Scandinavia with one of the +ptarmigans, and their leks last from the middle of March to the middle of +May. In Australia the lyre-bird (Menura superba) forms "small round +hillocks," and the M. Alberti scratches for itself shallow holes, or, as +they are called by the natives, "corroborying places," where it is believed +both sexes assemble. The meetings of the M. superba are sometimes very +large; and an account has lately been published (3. Quoted by Mr. T.W. +Wood, in the 'Student,' April 1870, p. 125.) by a traveller, who heard in a +valley beneath him, thickly covered with scrub, "a din which completely +astonished" him; on crawling onwards he beheld, to his amazement, about one +hundred and fifty of the magnificent lyre-cocks, "ranged in order of +battle, and fighting with indescribable fury." The bowers of the Bower- +birds are the resort of both sexes during the breeding-season; and "here +the males meet and contend with each other for the favours of the female, +and here the latter assemble and coquet with the males." With two of the +genera, the same bower is resorted to during many years. (4. Gould, +'Handbook to the Birds of Australia,' vol. i. pp. 300, 308, 448, 451. On +the ptarmigan, above alluded to, see Lloyd, ibid. p. 129.) + +The common magpie (Corvus pica, Linn.), as I have been informed by the Rev. +W. Darwin Fox, used to assemble from all parts of Delamere Forest, in order +to celebrate the "great magpie marriage." Some years ago these birds +abounded in extraordinary numbers, so that a gamekeeper killed in one +morning nineteen males, and another killed by a single shot seven birds at +roost together. They then had the habit of assembling very early in the +spring at particular spots, where they could be seen in flocks, chattering, +sometimes fighting, bustling and flying about the trees. The whole affair +was evidently considered by the birds as one of the highest importance. +Shortly after the meeting they all separated, and were then observed by Mr. +Fox and others to be paired for the season. In any district in which a +species does not exist in large numbers, great assemblages cannot, of +course, be held, and the same species may have different habits in +different countries. For instance, I have heard of only one instance, from +Mr. Wedderburn, of a regular assemblage of black game in Scotland, yet +these assemblages are so well known in Germany and Scandinavia that they +have received special names. + +UNPAIRED BIRDS. + +From the facts now given, we may conclude that the courtship of birds +belonging to widely different groups, is often a prolonged, delicate, and +troublesome affair. There is even reason to suspect, improbable as this +will at first appear, that some males and females of the same species, +inhabiting the same district, do not always please each other, and +consequently do not pair. Many accounts have been published of either the +male or female of a pair having been shot, and quickly replaced by another. +This has been observed more frequently with the magpie than with any other +bird, owing perhaps to its conspicuous appearance and nest. The +illustrious Jenner states that in Wiltshire one of a pair was daily shot no +less than seven times successively, "but all to no purpose, for the +remaining magpie soon found another mate"; and the last pair reared their +young. A new partner is generally found on the succeeding day; but Mr. +Thompson gives the case of one being replaced on the evening of the same +day. Even after the eggs are hatched, if one of the old birds is destroyed +a mate will often be found; this occurred after an interval of two days, in +a case recently observed by one of Sir J. Lubbock's keepers. (5. On +magpies, Jenner, in 'Philosophical Transactions,' 1824, p. 21. +Macgillivray, 'Hist. British Birds,' vol. i. p. 570. Thompson, in 'Annals +and Magazine of Natural History,' vol. viii. 1842, p. 494.) The first and +most obvious conjecture is that male magpies must be much more numerous +than females; and that in the above cases, as well as in many others which +could be given, the males alone had been killed. This apparently holds +good in some instances, for the gamekeepers in Delamere Forest assured Mr. +Fox that the magpies and carrion-crows which they formerly killed in +succession in large numbers near their nests, were all males; and they +accounted for this fact by the males being easily killed whilst bringing +food to the sitting females. Macgillivray, however, gives, on the +authority of an excellent observer, an instance of three magpies +successively killed on the same nest, which were all females; and another +case of six magpies successively killed whilst sitting on the same eggs, +which renders it probable that most of them were females; though, as I hear +from Mr. Fox, the male will sit on the eggs when the female is killed. + +Sir J. Lubbock's gamekeeper has repeatedly shot, but how often he could not +say, one of a pair of jays (Garrulus glandarius), and has never failed +shortly afterwards to find the survivor re-matched. Mr. Fox, Mr. F. Bond, +and others have shot one of a pair of carrion-crows (Corvus corone), but +the nest was soon again tenanted by a pair. These birds are rather common; +but the peregrine-falcon (Falco peregrinus) is rare, yet Mr. Thompson +states that in Ireland "if either an old male or female be killed in the +breeding-season (not an uncommon circumstance), another mate is found +within a very few days, so that the eyries, notwithstanding such +casualties, are sure to turn out their complement of young." Mr. Jenner +Weir has known the same thing with the peregrine-falcons at Beachy Head. +The same observer informs me that three kestrels (Falco tinnunculus), all +males, were killed one after the other whilst attending the same nest; two +of these were in mature plumage, but the third was in the plumage of the +previous year. Even with the rare golden eagle (Aquila chrysaetos), Mr. +Birkbeck was assured by a trustworthy gamekeeper in Scotland, that if one +is killed, another is soon found. So with the white owl (Strix flammea), +"the survivor readily found a mate, and the mischief went on." + +White of Selborne, who gives the case of the owl, adds that he knew a man, +who from believing that partridges when paired were disturbed by the males +fighting, used to shoot them; and though he had widowed the same female +several times, she always soon found a fresh partner. This same naturalist +ordered the sparrows, which deprived the house-martins of their nests, to +be shot; but the one which was left, "be it cock or hen, presently procured +a mate, and so for several times following." I could add analogous cases +relating to the chaffinch, nightingale, and redstart. With respect to the +latter bird (Phoenicura ruticilla), a writer expresses much surprise how +the sitting female could so soon have given effectual notice that she was a +widow, for the species was not common in the neighbourhood. Mr. Jenner +Weir has mentioned to me a nearly similar case; at Blackheath he never sees +or hears the note of the wild bullfinch, yet when one of his caged males +has died, a wild one in the course of a few days has generally come and +perched near the widowed female, whose call-note is not loud. I will give +only one other fact, on the authority of this same observer; one of a pair +of starlings (Sturnus vulgaris) was shot in the morning; by noon a new mate +was found; this was again shot, but before night the pair was complete; so +that the disconsolate widow or widower was thrice consoled during the same +day. Mr. Engleheart also informs me that he used during several years to +shoot one of a pair of starlings which built in a hole in a house at +Blackheath; but the loss was always immediately repaired. During one +season he kept an account, and found that he had shot thirty-five birds +from the same nest; these consisted of both males and females, but in what +proportion he could not say: nevertheless, after all this destruction, a +brood was reared. (6. On the peregrine falcon, see Thompson, 'Nat. Hist. +of Ireland: Birds,' vol. i. 1849, p. 39. On owls, sparrows, and +partridges, see White, 'Nat. Hist. of Selborne,' edit. of 1825, vol. i. p. +139. On the Phoenicura, see Loudon's 'Mag. of Nat. Hist.' vol. vii. 1834, +p. 245. Brehm ('Thierleben,' B. iv. s. 991) also alludes to cases of birds +thrice mated during the same day.) + +These facts well deserve attention. How is it that there are birds enough +ready to replace immediately a lost mate of either sex? Magpies, jays, +carrion-crows, partridges, and some other birds, are always seen during the +spring in pairs, and never by themselves; and these offer at first sight +the most perplexing cases. But birds of the same sex, although of course +not truly paired, sometimes live in pairs or in small parties, as is known +to be the case with pigeons and partridges. Birds also sometimes live in +triplets, as has been observed with starlings, carrion-crows, parrots, and +partridges. With partridges two females have been known to live with one +male, and two males with one female. In all such cases it is probable that +the union would be easily broken; and one of the three would readily pair +with a widow or widower. The males of certain birds may occasionally be +heard pouring forth their love-song long after the proper time, shewing +that they have either lost or never gained a mate. Death from accident or +disease of one of a pair would leave the other free and single; and there +is reason to believe that female birds during the breeding-season are +especially liable to premature death. Again, birds which have had their +nests destroyed, or barren pairs, or retarded individuals, would easily be +induced to desert their mates, and would probably be glad to take what +share they could of the pleasures and duties of rearing offspring although +not their own. (7. See White ('Nat. Hist. of Selborne,' 1825, vol. i. p. +140) on the existence, early in the season, of small coveys of male +partridges, of which fact I have heard other instances. See Jenner, on the +retarded state of the generative organs in certain birds, in 'Phil. +Transact.' 1824. In regard to birds living in triplets, I owe to Mr. +Jenner Weir the cases of the starlings and parrots, and to Mr. Fox, of +partridges; on carrion-crows, see the 'Field,' 1868, p. 415. On various +male birds singing after the proper period, see Rev. L. Jenyns, +'Observations in Natural History,' 1846, p. 87.) Such contingencies as +these probably explain most of the foregoing cases. (8. The following +case has been given ('The Times,' Aug. 6, 1868) by the Rev. F.O. Morris, on +the authority of the Hon. and Rev. O.W. Forester. "The gamekeeper here +found a hawk's nest this year, with five young ones on it. He took four +and killed them, but left one with its wings clipped as a decoy to destroy +the old ones by. They were both shot next day, in the act of feeding the +young one, and the keeper thought it was done with. The next day he came +again and found two other charitable hawks, who had come with an adopted +feeling to succour the orphan. These two he killed, and then left the +nest. On returning afterwards he found two more charitable individuals on +the same errand of mercy. One of these he killed; the other he also shot, +but could not find. No more came on the like fruitless errand.") +Nevertheless, it is a strange fact that within the same district, during +the height of the breeding-season, there should be so many males and +females always ready to repair the loss of a mated bird. Why do not such +spare birds immediately pair together? Have we not some reason to suspect, +and the suspicion has occurred to Mr. Jenner Weir, that as the courtship of +birds appears to be in many cases prolonged and tedious, so it occasionally +happens that certain males and females do not succeed, during the proper +season, in exciting each other's love, and consequently do not pair? This +suspicion will appear somewhat less improbable after we have seen what +strong antipathies and preferences female birds occasionally evince towards +particular males. + +MENTAL QUALITIES OF BIRDS, AND THEIR TASTE FOR THE BEAUTIFUL. + +Before we further discuss the question whether the females select the more +attractive males or accept the first whom they may encounter, it will be +advisable briefly to consider the mental powers of birds. Their reason is +generally, and perhaps justly, ranked as low; yet some facts could be given +leading to an opposite conclusion. (9. I am indebted to Prof. Newton for +the following passage from Mr. Adam's 'Travels of a Naturalist,' 1870, p. +278. Speaking of Japanese nut-hatches in confinement, he says: "Instead +of the more yielding fruit of the yew, which is the usual food of the nut- +hatch of Japan, at one time I substituted hard hazel-nuts. As the bird was +unable to crack them, he placed them one by one in his water-glass, +evidently with the notion that they would in time become softer--an +interesting proof of intelligence on the part of these birds.") Low powers +of reasoning, however, are compatible, as we see with mankind, with strong +affections, acute perception, and a taste for the beautiful; and it is with +these latter qualities that we are here concerned. It has often been said +that parrots become so deeply attached to each other that when one dies the +other pines for a long time; but Mr. Jenner Weir thinks that with most +birds the strength of their affection has been much exaggerated. +Nevertheless when one of a pair in a state of nature has been shot, the +survivor has been heard for days afterwards uttering a plaintive call; and +Mr. St. John gives various facts proving the attachment of mated birds. +(10. 'A Tour in Sutherlandshire,' vol. i. 1849, p. 185. Dr. Buller says +('Birds of New Zealand,' 1872, p. 56) that a male King Lory was killed; and +the female "fretted and moped, refused her food, and died of a broken +heart.") Mr. Bennett relates (11. 'Wanderings in New South Wales,' vol. +ii. 1834, p. 62.) that in China after a drake of the beautiful mandarin +Teal had been stolen, the duck remained disconsolate, though sedulously +courted by another mandarin drake, who displayed before her all his charms. +After an interval of three weeks the stolen drake was recovered, and +instantly the pair recognised each other with extreme joy. On the other +hand, starlings, as we have seen, may be consoled thrice in the same day +for the loss of their mates. Pigeons have such excellent local memories, +that they have been known to return to their former homes after an interval +of nine months, yet, as I hear from Mr. Harrison Weir, if a pair which +naturally would remain mated for life be separated for a few weeks during +the winter, and afterwards matched with other birds, the two when brought +together again, rarely, if ever, recognise each other. + +Birds sometimes exhibit benevolent feelings; they will feed the deserted +young ones even of distinct species, but this perhaps ought to be +considered as a mistaken instinct. They will feed, as shewn in an earlier +part of this work, adult birds of their own species which have become +blind. Mr. Buxton gives a curious account of a parrot which took care of a +frost-bitten and crippled bird of a distinct species, cleansed her +feathers, and defended her from the attacks of the other parrots which +roamed freely about his garden. It is a still more curious fact that these +birds apparently evince some sympathy for the pleasures of their fellows. +When a pair of cockatoos made a nest in an acacia tree, "it was ridiculous +to see the extravagant interest taken in the matter by the others of the +same species." These parrots, also, evinced unbounded curiosity, and +clearly had "the idea of property and possession." (12. 'Acclimatization +of Parrots,' by C. Buxton, M.P., 'Annals and Mag. of Nat. Hist.' Nov. 1868, +p. 381.) They have good memories, for in the Zoological Gardens they have +plainly recognised their former masters after an interval of some months. + +Birds possess acute powers of observation. Every mated bird, of course, +recognises its fellow. Audubon states that a certain number of mocking- +thrushes (Mimus polyglottus) remain all the year round in Louisiana, whilst +others migrate to the Eastern States; these latter, on their return, are +instantly recognised, and always attacked, by their southern brethren. +Birds under confinement distinguish different persons, as is proved by the +strong and permanent antipathy or affection which they shew, without any +apparent cause, towards certain individuals. I have heard of numerous +instances with jays, partridges, canaries, and especially bullfinches. Mr. +Hussey has described in how extraordinary a manner a tamed partridge +recognised everybody: and its likes and dislikes were very strong. This +bird seemed "fond of gay colours, and no new gown or cap could be put on +without catching his attention." (13. The 'Zoologist,' 1847-48, p. 1602.) +Mr. Hewitt has described the habits of some ducks (recently descended from +wild birds), which, at the approach of a strange dog or cat, would rush +headlong into the water, and exhaust themselves in their attempts to +escape; but they knew Mr. Hewitt's own dogs and cats so well that they +would lie down and bask in the sun close to them. They always moved away +from a strange man, and so they would from the lady who attended them if +she made any great change in her dress. Audubon relates that he reared and +tamed a wild turkey which always ran away from any strange dog; this bird +escaped into the woods, and some days afterwards Audubon saw, as he +thought, a wild turkey, and made his dog chase it; but, to his +astonishment, the bird did not run away, and the dog, when he came up, did +not attack the bird, for they mutually recognised each other as old +friends. (14. Hewitt on wild ducks, 'Journal of Horticulture,' Jan. 13, +1863, p. 39. Audubon on the wild turkey, 'Ornithological Biography,' vol. +i. p. 14. On the mocking-thrush, ibid. vol. i. p. 110.) + +Mr. Jenner Weir is convinced that birds pay particular attention to the +colours of other birds, sometimes out of jealousy, and sometimes as a sign +of kinship. Thus he turned a reed-bunting (Emberiza schoeniculus), which +had acquired its black head-dress, into his aviary, and the new-comer was +not noticed by any bird, except by a bullfinch, which is likewise black- +headed. This bullfinch was a very quiet bird, and had never before +quarrelled with any of its comrades, including another reed-bunting, which +had not as yet become black-headed: but the reed-bunting with a black head +was so unmercifully treated that it had to be removed. Spiza cyanea, +during the breeding-season, is of a bright blue colour; and though +generally peaceable, it attacked S. ciris, which has only the head blue, +and completely scalped the unfortunate bird. Mr. Weir was also obliged to +turn out a robin, as it fiercely attacked all the birds in his aviary with +any red in their plumage, but no other kinds; it actually killed a red- +breasted crossbill, and nearly killed a goldfinch. On the other band, he +has observed that some birds, when first introduced, fly towards the +species which resemble them most in colour, and settle by their sides. + +As male birds display their fine plumage and other ornaments with so much +care before the females, it is obviously probable that these appreciate the +beauty of their suitors. It is, however, difficult to obtain direct +evidence of their capacity to appreciate beauty. When birds gaze at +themselves in a looking-glass (of which many instances have been recorded) +we cannot feel sure that it is not from jealousy of a supposed rival, +though this is not the conclusion of some observers. In other cases it is +difficult to distinguish between mere curiosity and admiration. It is +perhaps the former feeling which, as stated by Lord Lilford (15. The +'Ibis,' vol. ii. 1860, p. 344.), attracts the ruff towards any bright +object, so that, in the Ionian Islands, "it will dart down to a bright- +coloured handkerchief, regardless of repeated shots." The common lark is +drawn down from the sky, and is caught in large numbers, by a small mirror +made to move and glitter in the sun. Is it admiration or curiosity which +leads the magpie, raven, and some other birds to steal and secrete bright +objects, such as silver articles or jewels? + +Mr. Gould states that certain humming-birds decorate the outsides of their +nests "with the utmost taste; they instinctively fasten thereon beautiful +pieces of flat lichen, the larger pieces in the middle, and the smaller on +the part attached to the branch. Now and then a pretty feather is +intertwined or fastened to the outer sides, the stem being always so placed +that the feather stands out beyond the surface." The best evidence, +however, of a taste for the beautiful is afforded by the three genera of +Australian bower-birds already mentioned. Their bowers (Fig. 46), where +the sexes congregate and play strange antics, are variously constructed, +but what most concerns us is, that they are decorated by the several +species in a different manner. The Satin bower-bird collects gaily- +coloured articles, such as the blue tail-feathers of parrakeets, bleached +bones and shells, which it sticks between the twigs or arranges at the +entrance. Mr. Gould found in one bower a neatly-worked stone tomahawk and +a slip of blue cotton, evidently procured from a native encampment. These +objects are continually re-arranged, and carried about by the birds whilst +at play. The bower of the Spotted bower-bird "is beautifully lined with +tall grasses, so disposed that the heads nearly meet, and the decorations +are very profuse." Round stones are used to keep the grass-stems in their +proper places, and to make divergent paths leading to the bower. The +stones and shells are often brought from a great distance. The Regent +bird, as described by Mr. Ramsay, ornaments its short bower with bleached +land-shells belonging to five or six species, and with "berries of various +colours, blue, red, and black, which give it when fresh a very pretty +appearance. Besides these there were several newly-picked leaves and young +shoots of a pinkish colour, the whole showing a decided taste for the +beautiful." Well may Mr. Gould say that "these highly decorated halls of +assembly must be regarded as the most wonderful instances of bird- +architecture yet discovered;" and the taste, as we see, of the several +species certainly differs. (16. On the ornamented nests of humming-birds, +Gould, 'Introduction to the Trochilidae,' 1861, p. 19. On the bower-birds, +Gould, 'Handbook to the Birds of Australia,' 1865, vol. i. pp. 444-461. +Ramsay, in the 'Ibis,' 1867, p. 456.) + +PREFERENCE FOR PARTICULAR MALES BY THE FEMALES. + +Having made these preliminary remarks on the discrimination and taste of +birds, I will give all the facts known to me which bear on the preference +shewn by the female for particular males. It is certain that distinct +species of birds occasionally pair in a state of nature and produce +hybrids. Many instances could be given: thus Macgillivray relates how a +male blackbird and female thrush "fell in love with each other," and +produced offspring. (17. 'History of Brit. Birds,' vol. ii. p. 92.) +Several years ago eighteen cases had been recorded of the occurrence in +Great Britain of hybrids between the black grouse and pheasant (18. +'Zoologist,' 1853-1854, p. 3946.); but most of these cases may perhaps be +accounted for by solitary birds not finding one of their own species to +pair with. With other birds, as Mr. Jenner Weir has reason to believe, +hybrids are sometimes the result of the casual intercourse of birds +building in close proximity. But these remarks do not apply to the many +recorded instances of tamed or domestic birds, belonging to distinct +species, which have become absolutely fascinated with each other, although +living with their own species. Thus Waterton (19. Waterton, 'Essays on +Nat. Hist.' 2nd series, pp. 42 and 117. For the following statements see +on the wigeon, 'Loudon's Mag. of Nat. Hist.' vol. ix. p. 616; L. Lloyd, +'Scandinavian Adventures,' vol. i. 1854, p. 452. Dixon, 'Ornamental and +Domestic Poultry,' p. 137; Hewitt, in 'Journal of Horticulture,' Jan. 13, +1863, p. 40; Bechstein, 'Stubenvögel,' 1840, s. 230. Mr. J. Jenner Weir +has lately given me an analogous case with ducks of two species.) states +that out of a flock of twenty-three Canada geese, a female paired with a +solitary Bernicle gander, although so different in appearance and size; and +they produced hybrid offspring. A male wigeon (Mareca penelope), living +with females of the same species, has been known to pair with a pintail +duck, Querquedula acuta. Lloyd describes the remarkable attachment between +a shield-drake (Tadorna vulpanser) and a common duck. Many additional +instances could be given; and the Rev. E.S. Dixon remarks that "those who +have kept many different species of geese together well know what +unaccountable attachments they are frequently forming, and that they are +quite as likely to pair and rear young with individuals of a race (species) +apparently the most alien to themselves as with their own stock." + +The Rev. W.D. Fox informs me that he possessed at the same time a pair of +Chinese geese (Anser cygnoides), and a common gander with three geese. The +two lots kept quite separate, until the Chinese gander seduced one of the +common geese to live with him. Moreover, of the young birds hatched from +the eggs of the common geese, only four were pure, the other eighteen +proving hybrids; so that the Chinese gander seems to have had prepotent +charms over the common gander. I will give only one other case; Mr. Hewitt +states that a wild duck, reared in captivity, "after breeding a couple of +seasons with her own mallard, at once shook him off on my placing a male +Pintail on the water. It was evidently a case of love at first sight, for +she swam about the new-comer caressingly, though he appeared evidently +alarmed and averse to her overtures of affection. From that hour she +forgot her old partner. Winter passed by, and the next spring the pintail +seemed to have become a convert to her blandishments, for they nested and +produced seven or eight young ones." + +What the charm may have been in these several cases, beyond mere novelty, +we cannot even conjecture. Colour, however, sometimes comes into play; for +in order to raise hybrids from the siskin (Fringilla spinus) and the +canary, it is much the best plan, according to Bechstein, to place birds of +the same tint together. Mr. Jenner Weir turned a female canary into his +aviary, where there were male linnets, goldfinches, siskins, greenfinches, +chaffinches, and other birds, in order to see which she would choose; but +there never was any doubt, and the greenfinch carried the day. They paired +and produced hybrid offspring. + +The fact of the female preferring to pair with one male rather than with +another of the same species is not so likely to excite attention, as when +this occurs, as we have just seen, between distinct species. The former +cases can best be observed with domesticated or confined birds; but these +are often pampered by high feeding, and sometimes have their instincts +vitiated to an extreme degree. Of this latter fact I could give sufficient +proofs with pigeons, and especially with fowls, but they cannot be here +related. Vitiated instincts may also account for some of the hybrid unions +above mentioned; but in many of these cases the birds were allowed to range +freely over large ponds, and there is no reason to suppose that they were +unnaturally stimulated by high feeding. + +With respect to birds in a state of nature, the first and most obvious +supposition which will occur to every one is that the female at the proper +season accepts the first male whom she may encounter; but she has at least +the opportunity for exerting a choice, as she is almost invariably pursued +by many males. Audubon--and we must remember that he spent a long life in +prowling about the forests of the United States and observing the birds-- +does not doubt that the female deliberately chooses her mate; thus, +speaking of a woodpecker, he says the hen is followed by half-a-dozen gay +suitors, who continue performing strange antics, "until a marked preference +is shewn for one." The female of the red-winged starling (Agelaeus +phoeniceus) is likewise pursued by several males, "until, becoming +fatigued, she alights, receives their addresses, and soon makes a choice." +He describes also how several male night-jars repeatedly plunge through the +air with astonishing rapidity, suddenly turning, and thus making a singular +noise; "but no sooner has the female made her choice than the other males +are driven away." With one of the vultures (Cathartes aura) of the United +States, parties of eight, ten, or more males and females assemble on fallen +logs, "exhibiting the strongest desire to please mutually," and after many +caresses, each male leads off his partner on the wing. Audubon likewise +carefully observed the wild flocks of Canada geese (Anser canadensis), and +gives a graphic description of their love-antics; he says that the birds +which had been previously mated "renewed their courtship as early as the +month of January, while the others would be contending or coquetting for +hours every day, until all seemed satisfied with the choice they had made, +after which, although they remained together, any person could easily +perceive that they were careful to keep in pairs. I have observed also +that the older the birds the shorter were the preliminaries of their +courtship. The bachelors and old maids whether in regret, or not caring to +be disturbed by the bustle, quietly moved aside and lay down at some +distance from the rest." (20. Audubon, 'Ornithological Biography,' vol. +i. pp. 191, 349; vol. ii. pp. 42, 275; vol. iii. p. 2.) Many similar +statements with respect to other birds could be cited from this same +observer. + +Turning now to domesticated and confined birds, I will commence by giving +what little I have learnt respecting the courtship of fowls. I have +received long letters on this subject from Messrs. Hewitt and Tegetmeier, +and almost an essay from the late Mr. Brent. It will be admitted by every +one that these gentlemen, so well known from their published works, are +careful and experienced observers. They do not believe that the females +prefer certain males on account of the beauty of their plumage; but some +allowance must be made for the artificial state under which these birds +have long been kept. Mr. Tegetmeier is convinced that a gamecock, though +disfigured by being dubbed and with his hackles trimmed, would be accepted +as readily as a male retaining all his natural ornaments. Mr. Brent, +however, admits that the beauty of the male probably aids in exciting the +female; and her acquiescence is necessary. Mr. Hewitt is convinced that +the union is by no means left to mere chance, for the female almost +invariably prefers the most vigorous, defiant, and mettlesome male; hence +it is almost useless, as he remarks, "to attempt true breeding if a game- +cock in good health and condition runs the locality, for almost every hen +on leaving the roosting-place will resort to the game-cock, even though +that bird may not actually drive away the male of her own variety." Under +ordinary circumstances the males and females of the fowl seem to come to a +mutual understanding by means of certain gestures, described to me by Mr. +Brent. But hens will often avoid the officious attentions of young males. +Old hens, and hens of a pugnacious disposition, as the same writer informs +me, dislike strange males, and will not yield until well beaten into +compliance. Ferguson, however, describes how a quarrelsome hen was subdued +by the gentle courtship of a Shanghai cock. (21. 'Rare and Prize +Poultry,' 1854, p. 27.) + +There is reason to believe that pigeons of both sexes prefer pairing with +birds of the same breed; and dovecot-pigeons dislike all the highly +improved breeds. (22. 'Variation of Animals and Plants under +Domestication,' vol. ii. p. 103.) Mr. Harrison Weir has lately heard from +a trustworthy observer, who keeps blue pigeons, that these drive away all +other coloured varieties, such as white, red, and yellow; and from another +observer, that a female dun carrier could not, after repeated trials, be +matched with a black male, but immediately paired with a dun. Again, Mr. +Tegetmeier had a female blue turbit that obstinately refused to pair with +two males of the same breed, which were successively shut up with her for +weeks; but on being let out she would have immediately accepted the first +blue dragon that offered. As she was a valuable bird, she was then shut up +for many weeks with a silver (i.e., very pale blue) male, and at last mated +with him. Nevertheless, as a general rule, colour appears to have little +influence on the pairing of pigeons. Mr. Tegetmeier, at my request, +stained some of his birds with magenta, but they were not much noticed by +the others. + +Female pigeons occasionally feel a strong antipathy towards certain males, +without any assignable cause. Thus MM. Boitard and Corbie, whose +experience extended over forty-five years, state: "Quand une femelle +éprouve de l'antipathie pour un mâle avec lequel on veut l'accoupler, +malgré tous les feux de l'amour, malgré l'alpiste et le chenevis dont on la +nourrit pour augmenter son ardeur, malgré un emprisonnement de six mois et +même d'un an, elle refuse constamment ses caresses; les avances empressées, +les agaceries, les tournoiemens, les tendres roucoulemens, rien ne peut lui +plaire ni l'émouvoir; gonflée, boudeuse, blottie dans un coin de sa prison, +elle n'en sort que pour boire et manger, ou pour repousser avec une espèce +de rage des caresses devenues trop pressantes." (23. Boitard and Corbie, +'Les Pigeons,' etc., 1824, p. 12. Prosper Lucas ('Traité de l'Héréd. Nat.' +tom. ii. 1850, p. 296) has himself observed nearly similar facts with +pigeons.) On the other hand, Mr. Harrison Weir has himself observed, and +has heard from several breeders, that a female pigeon will occasionally +take a strong fancy for a particular male, and will desert her own mate for +him. Some females, according to another experienced observer, Riedel (24. +Die Taubenzucht, 1824, s. 86.), are of a profligate disposition, and prefer +almost any stranger to their own mate. Some amorous males, called by our +English fanciers "gay birds," are so successful in their gallantries, that, +as Mr. H. Weir informs me, they must be shut up on account of the mischief +which they cause. + +Wild turkeys in the United States, according to Audubon, "sometimes pay +their addresses to the domesticated females, and are generally received by +them with great pleasure." So that these females apparently prefer the +wild to their own males. (25. 'Ornithological Biography,' vol. i. p. 13. +See to the same effect, Dr. Bryant, in Allen's 'Mammals and Birds of +Florida,' p. 344.) + +Here is a more curious case. Sir R. Heron during many years kept an +account of the habits of the peafowl, which he bred in large numbers. He +states that "the hens have frequently great preference to a particular +peafowl. They were all so fond of an old pied cock, that one year, when he +was confined, though still in view, they were constantly assembled close to +the trellice-walls of his prison, and would not suffer a japanned peacock +to touch them. On his being let out in the autumn, the oldest of the hens +instantly courted him and was successful in her courtship. The next year +he was shut up in a stable, and then the hens all courted his rival." (26. +'Proceedings, Zoological Society,' 1835, p. 54. The japanned peacock is +considered by Mr. Sclater as a distinct species, and has been named Pavo +nigripennis; but the evidence seems to me to show that it is only a +variety.) This rival was a japanned or black-winged peacock, to our eyes a +more beautiful bird than the common kind. + +Lichtenstein, who was a good observer and had excellent opportunities of +observation at the Cape of Good Hope, assured Rudolphi that the female +widow-bird (Chera progne) disowns the male when robbed of the long tail- +feathers with which he is ornamented during the breeding-season. I presume +that this observation must have been made on birds under confinement. (27. +Rudolphi, 'Beiträge zur Anthropologie,' 1812, s. 184.) Here is an +analogous case; Dr. Jaeger (28. 'Die Darwin'sche Theorie, und ihre +Stellung zu Moral und Religion,' 1869, s. 59.), director of the Zoological +Gardens of Vienna, states that a male silver-pheasant, who had been +triumphant over all other males and was the accepted lover of the females, +had his ornamental plumage spoiled. He was then immediately superseded by +a rival, who got the upper hand and afterwards led the flock. + +It is a remarkable fact, as shewing how important colour is in the +courtship of birds, that Mr. Boardman, a well-known collector and observer +of birds for many years in the Northern United States, has never in his +large experience seen an albino paired with another bird; yet he has had +opportunities of observing many albinos belonging to several species. (29. +This statement is given by Mr. A. Leith Adams, in his 'Field and Forest +Rambles,' 1873, p. 76, and accords with his own experience.) It can hardly +be maintained that albinos in a state of nature are incapable of breeding, +as they can be raised with the greatest facility under confinement. It +appears, therefore, that we must attribute the fact that they do not pair +to their rejection by their normally coloured comrades. + +Female birds not only exert a choice, but in some few cases they court the +male, or even fight together for his possession. Sir R. Heron states that +with peafowl, the first advances are always made by the female; something +of the same kind takes place, according to Audubon, with the older females +of the wild turkey. With the capercailzie, the females flit round the male +whilst he is parading at one of the places of assemblage, and solicit his +attention. (30. In regard to peafowl, see Sir R. Heron, 'Proc. Zoolog. +Soc.' 1835, p. 54, and the Rev. E.S. Dixon, 'Ornamental Poultry,' 1848, p. +8. For the turkey, Audubon, ibid. p. 4. For the capercailzie, Lloyd, +'Game Birds of Sweden,' 1867, p. 23.) We have seen that a tame wild-duck +seduced an unwilling pintail drake after a long courtship. Mr. Bartlett +believes that the Lophophorus, like many other gallinaceous birds, is +naturally polygamous, but two females cannot be placed in the same cage +with a male, as they fight so much together. The following instance of +rivalry is more surprising as it relates to bullfinches, which usually pair +for life. Mr. Jenner Weir introduced a dull-coloured and ugly female into +his aviary, and she immediately attacked another mated female so +unmercifully that the latter had to be separated. The new female did all +the courtship, and was at last successful, for she paired with the male; +but after a time she met with a just retribution, for, ceasing to be +pugnacious, she was replaced by the old female, and the male then deserted +his new and returned to his old love. + +In all ordinary cases the male is so eager that he will accept any female, +and does not, as far as we can judge, prefer one to the other; but, as we +shall hereafter see, exceptions to this rule apparently occur in some few +groups. With domesticated birds, I have heard of only one case of males +shewing any preference for certain females, namely, that of the domestic +cock, who, according to the high authority of Mr. Hewitt, prefers the +younger to the older hens. On the other hand, in effecting hybrid unions +between the male pheasant and common hens, Mr. Hewitt is convinced that the +pheasant invariably prefers the older birds. He does not appear to be in +the least influenced by their colour; but "is most capricious in his +attachments" (31. Mr. Hewitt, quoted in Tegetmeier's 'Poultry Book,' 1866, +p. 165.): from some inexplicable cause he shews the most determined +aversion to certain hens, which no care on the part of the breeder can +overcome. Mr. Hewitt informs me that some hens are quite unattractive even +to the males of their own species, so that they may be kept with several +cocks during a whole season, and not one egg out of forty or fifty will +prove fertile. On the other hand, with the long-tailed duck (Harelda +glacialis), "it has been remarked," says M. Ekstrom, "that certain females +are much more courted than the rest. Frequently, indeed, one sees an +individual surrounded by six or eight amorous males." Whether this +statement is credible, I know not; but the native sportsmen shoot these +females in order to stuff them as decoys. (32. Quoted in Lloyd's 'Game +Birds of Sweden,' p. 345.) + +With respect to female birds feeling a preference for particular males, we +must bear in mind that we can judge of choice being exerted only by +analogy. If an inhabitant of another planet were to behold a number of +young rustics at a fair courting a pretty girl, and quarrelling about her +like birds at one of their places of assemblage, he would, by the eagerness +of the wooers to please her and to display their finery, infer that she had +the power of choice. Now with birds the evidence stands thus: they have +acute powers of observation, and they seem to have some taste for the +beautiful both in colour and sound. It is certain that the females +occasionally exhibit, from unknown causes, the strongest antipathies and +preferences for particular males. When the sexes differ in colour or in +other ornaments the males with rare exceptions are the more decorated, +either permanently or temporarily during the breeding-season. They +sedulously display their various ornaments, exert their voices, and perform +strange antics in the presence of the females. Even well-armed males, who, +it might be thought, would altogether depend for success on the law of +battle, are in most cases highly ornamented; and their ornaments have been +acquired at the expense of some loss of power. In other cases ornaments +have been acquired, at the cost of increased risk from birds and beasts of +prey. With various species many individuals of both sexes congregate at +the same spot, and their courtship is a prolonged affair. There is even +reason to suspect that the males and females within the same district do +not always succeed in pleasing each other and pairing. + +What then are we to conclude from these facts and considerations? Does the +male parade his charms with so much pomp and rivalry for no purpose? Are +we not justified in believing that the female exerts a choice, and that she +receives the addresses of the male who pleases her most? It is not +probable that she consciously deliberates; but she is most excited or +attracted by the most beautiful, or melodious, or gallant males. Nor need +it be supposed that the female studies each stripe or spot of colour; that +the peahen, for instance, admires each detail in the gorgeous train of the +peacock--she is probably struck only by the general effect. Nevertheless, +after hearing how carefully the male Argus pheasant displays his elegant +primary wing-feathers, and erects his ocellated plumes in the right +position for their full effect; or again, how the male goldfinch +alternately displays his gold-bespangled wings, we ought not to feel too +sure that the female does not attend to each detail of beauty. We can +judge, as already remarked, of choice being exerted, only from analogy; and +the mental powers of birds do not differ fundamentally from ours. From +these various considerations we may conclude that the pairing of birds is +not left to chance; but that those males, which are best able by their +various charms to please or excite the female, are under ordinary +circumstances accepted. If this be admitted, there is not much difficulty +in understanding how male birds have gradually acquired their ornamental +characters. All animals present individual differences, and as man can +modify his domesticated birds by selecting the individuals which appear to +him the most beautiful, so the habitual or even occasional preference by +the female of the more attractive males would almost certainly lead to +their modification; and such modifications might in the course of time be +augmented to almost any extent, compatible with the existence of the +species. + +VARIABILITY OF BIRDS, AND ESPECIALLY OF THEIR SECONDARY SEXUAL CHARACTERS. + +Variability and inheritance are the foundations for the work of selection. +That domesticated birds have varied greatly, their variations being +inherited, is certain. That birds in a state of nature have been modified +into distinct races is now universally admitted. (33. According to Dr. +Blasius ('Ibis,' vol. ii. 1860, p. 297), there are 425 indubitable species +of birds which breed in Europe, besides sixty forms, which are frequently +regarded as distinct species. Of the latter, Blasius thinks that only ten +are really doubtful, and that the other fifty ought to be united with their +nearest allies; but this shews that there must be a considerable amount of +variation with some of our European birds. It is also an unsettled point +with naturalists, whether several North American birds ought to be ranked +as specifically distinct from the corresponding European species. So again +many North American forms which until lately were named as distinct +species, are now considered to be local races.) Variations may be divided +into two classes; those which appear to our ignorance to arise +spontaneously, and those which are directly related to the surrounding +conditions, so that all or nearly all the individuals of the same species +are similarly modified. Cases of the latter kind have recently been +observed with care by Mr. J.A. Allen (34. 'Mammals and Birds of East +Florida,' also an 'Ornithological Reconnaissance of Kansas,' etc. +Notwithstanding the influence of climate on the colours of birds, it is +difficult to account for the dull or dark tints of almost all the species +inhabiting certain countries, for instance, the Galapagos Islands under the +equator, the wide temperate plains of Patagonia, and, as it appears, Egypt +(see Mr. Hartshorne in the 'American Naturalist,' 1873, p. 747). These +countries are open, and afford little shelter to birds; but it seems +doubtful whether the absence of brightly coloured species can be explained +on the principle of protection, for on the Pampas, which are equally open, +though covered by green grass, and where the birds would be equally exposed +to danger, many brilliant and conspicuously coloured species are common. I +have sometimes speculated whether the prevailing dull tints of the scenery +in the above named countries may not have affected the appreciation of +bright colours by the birds inhabiting them.), who shews that in the United +States many species of birds gradually become more strongly coloured in +proceeding southward, and more lightly coloured in proceeding westward to +the arid plains of the interior. Both sexes seem generally to be affected +in a like manner, but sometimes one sex more than the other. This result +is not incompatible with the belief that the colours of birds are mainly +due to the accumulation of successive variations through sexual selection; +for even after the sexes have been greatly differentiated, climate might +produce an equal effect on both sexes, or a greater effect on one sex than +on the other, owing to some constitutional difference. + +Individual differences between the members of the same species are admitted +by every one to occur under a state of nature. Sudden and strongly marked +variations are rare; it is also doubtful whether if beneficial they would +often be preserved through selection and transmitted to succeeding +generations. (35. 'Origin of Species' fifth edit. 1869, p.104. I had +always perceived, that rare and strongly-marked deviations of structure, +deserving to be called monstrosities, could seldom be preserved through +natural selection, and that the preservation of even highly-beneficial +variations would depend to a certain extent on chance. I had also fully +appreciated the importance of mere individual differences, and this led me +to insist so strongly on the importance of that unconscious form of +selection by man, which follows from the preservation of the most valued +individuals of each breed, without any intention on his part to modify the +characters of the breed. But until I read an able article in the 'North +British Review' (March 1867, p. 289, et seq.), which has been of more use +to me than any other Review, I did not see how great the chances were +against the preservation of variations, whether slight or strongly +pronounced, occurring only in single individuals.) Nevertheless, it may be +worth while to give the few cases which I have been able to collect, +relating chiefly to colour,--simple albinism and melanism being excluded. +Mr. Gould is well known to admit the existence of few varieties, for he +esteems very slight differences as specific; yet he states (36. +'Introduction to the Trochlidae,' p. 102.) that near Bogota certain +humming-birds belonging to the genus Cynanthus are divided into two or +three races or varieties, which differ from each other in the colouring of +the tail--"some having the whole of the feathers blue, while others have +the eight central ones tipped with beautiful green." It does not appear +that intermediate gradations have been observed in this or the following +cases. In the males alone of one of the Australian parrakeets "the thighs +in some are scarlet, in others grass-green." In another parrakeet of the +same country "some individuals have the band across the wing-coverts +bright-yellow, while in others the same part is tinged with red. (37. +Gould, 'Handbook to Birds of Australia,' vol. ii. pp. 32 and 68.) In the +United States some few of the males of the scarlet tanager (Tanagra rubra) +have "a beautiful transverse band of glowing red on the smaller wing- +coverts" (38. Audubon, 'Ornithological Biography,' 1838, vol. iv. p. +389.); but this variation seems to be somewhat rare, so that its +preservation through sexual selection would follow only under usually +favourable circumstances. In Bengal the Honey buzzard (Pernis cristata) +has either a small rudimental crest on its head, or none at all: so slight +a difference, however, would not have been worth notice, had not this same +species possessed in Southern India a well-marked occipital crest formed of +several graduated feathers." (39. Jerdon, 'Birds of India,' vol. i. p. +108; and Mr. Blyth, in 'Land and Water,' 1868, p. 381.) + +The following case is in some respects more interesting. A pied variety of +the raven, with the head, breast, abdomen, and parts of the wings and tail- +feathers white, is confined to the Feroe Islands. It is not very rare +there, for Graba saw during his visit from eight to ten living specimens. +Although the characters of this variety are not quite constant, yet it has +been named by several distinguished ornithologists as a distinct species. +The fact of the pied birds being pursued and persecuted with much clamour +by the other ravens of the island was the chief cause which led Brunnich to +conclude that they were specifically distinct; but this is now known to be +an error. (40. Graba, 'Tagebuch Reise nach Faro,' 1830, ss. 51-54. +Macgillivray, 'History of British Birds,' vol. iii. p. 745, 'Ibis,' vol. v. +1863, p. 469.) This case seems analogous to that lately given of albino +birds not pairing from being rejected by their comrades. + +In various parts of the northern seas a remarkable variety of the common +Guillemot (Uria troile) is found; and in Feroe, one out of every five +birds, according to Graba's estimation, presents this variation. It is +characterised (41. Graba, ibid. s. 54. Macgillivray, ibid. vol. v. p. +327.) by a pure white ring round the eye, with a curved narrow white line, +an inch and a half in length, extending back from the ring. This +conspicuous character has caused the bird to be ranked by several +ornithologists as a distinct species under the name of U. lacrymans, but it +is now known to be merely a variety. It often pairs with the common kind, +yet intermediate gradations have never been seen; nor is this surprising, +for variations which appear suddenly, are often, as I have elsewhere shewn +(42. 'Variation of Animals and Plants under Domestication,' vol. ii. p. +92.), transmitted either unaltered or not at all. We thus see that two +distinct forms of the same species may co-exist in the same district, and +we cannot doubt that if the one had possessed any advantage over the other, +it would soon have been multiplied to the exclusion of the latter. If, for +instance, the male pied ravens, instead of being persecuted by their +comrades, had been highly attractive (like the above pied peacock) to the +black female ravens their numbers would have rapidly increased. And this +would have been a case of sexual selection. + +With respect to the slight individual differences which are common, in a +greater or less degree, to all the members of the same species, we have +every reason to believe that they are by far the most important for the +work of selection. Secondary sexual characters are eminently liable to +vary, both with animals in a state of nature and under domestication. (43. +On these points see also 'Variation of Animals and Plants under +Domestication,' vol. i. p. 253; vol ii. pp. 73, 75.) There is also reason +to believe, as we have seen in our eighth chapter, that variations are more +apt to occur in the male than in the female sex. All these contingencies +are highly favourable for sexual selection. Whether characters thus +acquired are transmitted to one sex or to both sexes, depends, as we shall +see in the following chapter, on the form of inheritance which prevails. + +It is sometimes difficult to form an opinion whether certain slight +differences between the sexes of birds are simply the result of variability +with sexually-limited inheritance, without the aid of sexual selection, or +whether they have been augmented through this latter process. I do not +here refer to the many instances where the male displays splendid colours +or other ornaments, of which the female partakes to a slight degree; for +these are almost certainly due to characters primarily acquired by the male +having been more or less transferred to the female. But what are we to +conclude with respect to certain birds in which, for instance, the eyes +differ slightly in colour in the two sexes? (44. See, for instance, on +the irides of a Podica and Gallicrex in 'Ibis,' vol. ii. 1860, p. 206; and +vol. v. 1863, p. 426.) In some cases the eyes differ conspicuously; thus +with the storks of the genus Xenorhynchus, those of the male are blackish- +hazel, whilst those of the females are gamboge-yellow; with many hornbills +(Buceros), as I hear from Mr. Blyth (45. See also Jerdon, 'Birds of +India,' vol. i. pp. 243-245.), the males have intense crimson eyes, and +those of the females are white. In the Buceros bicornis, the hind margin +of the casque and a stripe on the crest of the beak are black in the male, +but not so in the female. Are we to suppose that these black marks and the +crimson colour of the eyes have been preserved or augmented through sexual +selection in the males? This is very doubtful; for Mr. Bartlett shewed me +in the Zoological Gardens that the inside of the mouth of this Buceros is +black in the male and flesh-coloured in the female; and their external +appearance or beauty would not be thus affected. I observed in Chile (46. +'Zoology of the Voyage of H.M.S. "Beagle,"' 1841, p. 6.) that the iris in +the condor, when about a year old, is dark-brown, but changes at maturity +into yellowish-brown in the male, and into bright red in the female. The +male has also a small, longitudinal, leaden-coloured, fleshy crest or comb. +The comb of many gallinaceous birds is highly ornamental, and assumes vivid +colours during the act of courtship; but what are we to think of the dull- +coloured comb of the condor, which does not appear to us in the least +ornamental? The same question may be asked in regard to various other +characters, such as the knob on the base of the beak of the Chinese goose +(Anser cygnoides), which is much larger in the male than in the female. No +certain answer can be given to these questions; but we ought to be cautious +in assuming that knobs and various fleshy appendages cannot be attractive +to the female, when we remember that with savage races of man various +hideous deformities--deep scars on the face with the flesh raised into +protuberances, the septum of the nose pierced by sticks or bones, holes in +the ears and lips stretched widely open--are all admired as ornamental. + +Whether or not unimportant differences between the sexes, such as those +just specified, have been preserved through sexual selection, these +differences, as well as all others, must primarily depend on the laws of +variation. On the principle of correlated development, the plumage often +varies on different parts of the body, or over the whole body, in the same +manner. We see this well illustrated in certain breeds of the fowl. In +all the breeds the feathers on the neck and loins of the males are +elongated, and are called hackles; now when both sexes acquire a top-knot, +which is a new character in the genus, the feathers on the head of the male +become hackle-shaped, evidently on the principle of correlation; whilst +those on the head of the female are of the ordinary shape. The colour also +of the hackles forming the top-knot of the male, is often correlated with +that of the hackles on the neck and loins, as may be seen by comparing +these feathers in the golden and silver-spangled Polish, the Houdans, and +Creve-coeur breeds. In some natural species we may observe exactly the +same correlation in the colours of these same feathers, as in the males of +the splendid Gold and Amherst pheasants. + +The structure of each individual feather generally causes any change in its +colouring to be symmetrical; we see this in the various laced, spangled, +and pencilled breeds of the fowl; and on the principle of correlation the +feathers over the whole body are often coloured in the same manner. We are +thus enabled without much trouble to rear breeds with their plumage marked +almost as symmetrically as in natural species. In laced and spangled fowls +the coloured margins of the feathers are abruptly defined; but in a mongrel +raised by me from a black Spanish cock glossed with green, and a white +game-hen, all the feathers were greenish-black, excepting towards their +extremities, which were yellowish-white; but between the white extremities +and the black bases, there was on each feather a symmetrical, curved zone +of dark-brown. In some instances the shaft of the feather determines the +distribution of the tints; thus with the body-feathers of a mongrel from +the same black Spanish cock and a silver-spangled Polish hen, the shaft, +together with a narrow space on each side, was greenish-black, and this was +surrounded by a regular zone of dark-brown, edged with brownish-white. In +these cases we have feathers symmetrically shaded, like those which give so +much elegance to the plumage of many natural species. I have also noticed +a variety of the common pigeon with the wing-bars symmetrically zoned with +three bright shades, instead of being simply black on a slaty-blue ground, +as in the parent-species. + +In many groups of birds the plumage is differently coloured in the several +species, yet certain spots, marks, or stripes are retained by all. +Analogous cases occur with the breeds of the pigeon, which usually retain +the two wing-bars, though they may be coloured red, yellow, white, black, +or blue, the rest of the plumage being of some wholly different tint. Here +is a more curious case, in which certain marks are retained, though +coloured in a manner almost exactly the opposite of what is natural; the +aboriginal pigeon has a blue tail, with the terminal halves of the outer +webs of the two outer tail feathers white; now there is a sub-variety +having a white instead of a blue tail, with precisely that part black which +is white in the parent-species. (47. Bechstein, 'Naturgeschichte +Deutschlands,' B. iv. 1795, s. 31, on a sub-variety of the Monck pigeon.) + +FORMATION AND VARIABILITY OF THE OCELLI OR EYE-LIKE SPOTS ON THE PLUMAGE OF +BIRDS. + +[Fig. 53. Cyllo leda, Linn., from a drawing by Mr. Trimen, shewing the +extreme range of variation in the ocelli. +A. Specimen, from Mauritius, upper surface of fore-wing. +A1. Specimen, from Natal, ditto. +B. Specimen, from Java, upper surface of hind-wing. +B1. Specimen, from Mauritius, ditto.] + +As no ornaments are more beautiful than the ocelli on the feathers of +various birds, on the hairy coats of some mammals, on the scales of +reptiles and fishes, on the skin of amphibians, on the wings of many +Lepidoptera and other insects, they deserve to be especially noticed. An +ocellus consists of a spot within a ring of another colour, like the pupil +within the iris, but the central spot is often surrounded by additional +concentric zones. The ocelli on the tail-coverts of the peacock offer a +familiar example, as well as those on the wings of the peacock-butterfly +(Vanessa). Mr. Trimen has given me a description of a S. African moth +(Gynanisa isis), allied to our Emperor moth, in which a magnificent ocellus +occupies nearly the whole surface of each hinder wing; it consists of a +black centre, including a semi-transparent crescent-shaped mark, surrounded +by successive, ochre-yellow, black, ochre-yellow, pink, white, pink, brown, +and whitish zones. Although we do not know the steps by which these +wonderfully beautiful and complex ornaments have been developed, the +process has probably been a simple one, at least with insects; for, as Mr. +Trimen writes to me, "no characters of mere marking or coloration are so +unstable in the Lepidoptera as the ocelli, both in number and size." Mr. +Wallace, who first called my attention to this subject, shewed me a series +of specimens of our common meadow-brown butterfly (Hipparchia janira) +exhibiting numerous gradations from a simple minute black spot to an +elegantly-shaded ocellus. In a S. African butterfly (Cyllo leda, Linn.), +belonging to the same family, the ocelli are even still more variable. In +some specimens (A, Fig. 53) large spaces on the upper surface of the wings +are coloured black, and include irregular white marks; and from this state +a complete gradation can be traced into a tolerably perfect ocellus (A1), +and this results from the contraction of the irregular blotches of colour. +In another series of specimens a gradation can be followed from excessively +minute white dots, surrounded by a scarcely visible black line (B), into +perfectly symmetrical and large ocelli (B1). (48. This woodcut has been +engraved from a beautiful drawing, most kindly made for me by Mr. Trimen; +see also his description of the wonderful amount of variation in the +coloration and shape of the wings of this butterfly, in his 'Rhopalocera +Africae Australis,' p. 186.) In cases like these, the development of a +perfect ocellus does not require a long course of variation and selection. + +With birds and many other animals, it seems to follow from the comparison +of allied species that circular spots are often generated by the breaking +up and contraction of stripes. In the Tragopan pheasant faint white lines +in the female represent the beautiful white spots in the male (49. Jerdon, +'Birds of India,' vol. iii. p. 517.); and something of the same kind may be +observed in the two sexes of the Argus pheasant. However this may be, +appearances strongly favour the belief that on the one hand, a dark spot is +often formed by the colouring matter being drawn towards a central point +from a surrounding zone, which latter is thus rendered lighter; and, on the +other hand, that a white spot is often formed by the colour being driven +away from a central point, so that it accumulates in a surrounding darker +zone. In either case an ocellus is the result. The colouring matter seems +to be a nearly constant quantity, but is redistributed, either +centripetally or centrifugally. The feathers of the common guinea-fowl +offer a good instance of white spots surrounded by darker zones; and +wherever the white spots are large and stand near each other, the +surrounding dark zones become confluent. In the same wing-feather of the +Argus pheasant dark spots may be seen surrounded by a pale zone, and white +spots by a dark zone. Thus the formation of an ocellus in its most +elementary state appears to be a simple affair. By what further steps the +more complex ocelli, which are surrounded by many successive zones of +colour, have been generated, I will not pretend to say. But the zoned +feathers of the mongrels from differently coloured fowls, and the +extraordinary variability of the ocelli on many Lepidoptera, lead us to +conclude that their formation is not a complex process, but depends on some +slight and graduated change in the nature of the adjoining tissues. + +GRADATION OF SECONDARY SEXUAL CHARACTERS. + +[Fig. 54. Feather of Peacock, about two-thirds of natural size, drawn by +Mr. Ford. The transparent zone is represented by the outermost white zone, +confined to the upper end of the disc.] + +Cases of gradation are important, as shewing us that highly complex +ornaments may be acquired by small successive steps. In order to discover +the actual steps by which the male of any existing bird has acquired his +magnificent colours or other ornaments, we ought to behold the long line of +his extinct progenitors; but this is obviously impossible. We may, +however, generally gain a clue by comparing all the species of the same +group, if it be a large one; for some of them will probably retain, at +least partially, traces of their former characters. Instead of entering on +tedious details respecting various groups, in which striking instances of +gradation could be given, it seems the best plan to take one or two +strongly marked cases, for instance that of the peacock, in order to see if +light can be thrown on the steps by which this bird bas become so +splendidly decorated. The peacock is chiefly remarkable from the +extraordinary length of his tail-coverts; the tail itself not being much +elongated. The barbs along nearly the whole length of these feathers stand +separate or are decomposed; but this is the case with the feathers of many +species, and with some varieties of the domestic fowl and pigeon. The +barbs coalesce towards the extremity of the shaft forming the oval disc or +ocellus, which is certainly one of the most beautiful objects in the world. +It consists of an iridescent, intensely blue, indented centre, surrounded +by a rich green zone, this by a broad coppery-brown zone, and this by five +other narrow zones of slightly different iridescent shades. A trifling +character in the disc deserves notice; the barbs, for a space along one of +the concentric zones are more or less destitute of their barbules, so that +a part of the disc is surrounded by an almost transparent zone, which gives +it a highly finished aspect. But I have elsewhere described (50. +'Variation of Animals and Plants under Domestication,' vol. i. p. 254.) an +exactly analogous variation in the hackles of a sub-variety of the game- +cock, in which the tips, having a metallic lustre, "are separated from the +lower part of the feather by a symmetrically shaped transparent zone, +composed of the naked portions of the barbs." The lower margin or base of +the dark-blue centre of the ocellus is deeply indented on the line of the +shaft. The surrounding zones likewise shew traces, as may be seen in the +drawing (Fig. 54), of indentations, or rather breaks. These indentations +are common to the Indian and Javan peacocks (Pavo cristatus and P. +muticus); and they seem to deserve particular attention, as probably +connected with the development of the ocellus; but for a long time I could +not conjecture their meaning. + +If we admit the principle of gradual evolution, there must formerly have +existed many species which presented every successive step between the +wonderfully elongated tail-coverts of the peacock and the short tail- +coverts of all ordinary birds; and again between the magnificent ocelli of +the former, and the simpler ocelli or mere coloured spots on other birds; +and so with all the other characters of the peacock. Let us look to the +allied Gallinaceae for any still-existing gradations. The species and sub- +species of Polyplectron inhabit countries adjacent to the native land of +the peacock; and they so far resemble this bird that they are sometimes +called peacock-pheasants. I am also informed by Mr. Bartlett that they +resemble the peacock in their voice and in some of their habits. During +the spring the males, as previously described, strut about before the +comparatively plain-coloured females, expanding and erecting their tail and +wing-feathers, which are ornamented with numerous ocelli. I request the +reader to turn back to the drawing (Fig. 51) of a Polyplectron; In P. +napoleonis the ocelli are confined to the tail, and the back is of a rich +metallic blue; in which respects this species approaches the Java peacock. +P. hardwickii possesses a peculiar top-knot, which is also somewhat like +that of the Java peacock. In all the species the ocelli on the wings and +tail are either circular or oval, and consist of a beautiful, iridescent, +greenish-blue or greenish-purple disc, with a black border. This border in +P. chinquis shades into brown, edged with cream colour, so that the ocellus +is here surrounded with variously shaded, though not bright, concentric +zones. The unusual length of the tail-coverts is another remarkable +character in Polyplectron; for in some of the species they are half, and in +others two-thirds as long as the true tail-feathers. The tail-coverts are +ocellated as in the peacock. Thus the several species of Polyplectron +manifestly make a graduated approach to the peacock in the length of their +tail-coverts, in the zoning of the ocelli, and in some other characters. + +[Fig. 55. Part of a tail-covert of Polyplectron chinquis, with the two +ocelli of natural size. + +Fig. 56. Part of a tail-covert of Polyplectron malaccense, with the two +ocelli, partially confluent, of natural size.] + +Notwithstanding this approach, the first species of Polyplectron which I +examined almost made me give up the search; for I found not only that the +true tail-feathers, which in the peacock are quite plain, were ornamented +with ocelli, but that the ocelli on all the feathers differed fundamentally +from those of the peacock, in there being two on the same feather (Fig. +55), one on each side of the shaft. Hence I concluded that the early +progenitors of the peacock could not have resembled a Polyplectron. But on +continuing my search, I observed that in some of the species the two ocelli +stood very near each other; that in the tail-feathers of P. hardwickii they +touched each other; and, finally, that on the tail-coverts of this same +species as well as of P. malaccense (Fig. 56) they were actually confluent. +As the central part alone is confluent, an indentation is left at both the +upper and lower ends; and the surrounding coloured zones are likewise +indented. A single ocellus is thus formed on each tail-covert, though +still plainly betraying its double origin. These confluent ocelli differ +from the single ocelli of the peacock in having an indentation at both +ends, instead of only at the lower or basal end. The explanation, however, +of this difference is not difficult; in some species of Polyplectron the +two oval ocelli on the same feather stand parallel to each other; in other +species (as in P. chinquis) they converge towards one end; now the partial +confluence of two convergent ocelli would manifestly leave a much deeper +indentation at the divergent than at the convergent end. It is also +manifest that if the convergence were strongly pronounced and the +confluence complete, the indentation at the convergent end would tend to +disappear. + +The tail-feathers in both species of the peacock are entirely destitute of +ocelli, and this apparently is related to their being covered up and +concealed by the long tail-coverts. In this respect they differ remarkably +from the tail-feathers of Polyplectron, which in most of the species are +ornamented with larger ocelli than those on the tail-coverts. Hence I was +led carefully to examine the tail-feathers of the several species, in order +to discover whether their ocelli shewed any tendency to disappear; and to +my great satisfaction, this appeared to be so. The central tail-feathers +of P. napoleonis have the two ocelli on each side of the shaft perfectly +developed; but the inner ocellus becomes less and less conspicuous on the +more exterior tail-feathers, until a mere shadow or rudiment is left on the +inner side of the outermost feather. Again, in P. malaccense, the ocelli +on the tail-coverts are, as we have seen, confluent; and these feathers are +of unusual length, being two-thirds of the length of the tail-feathers, so +that in both these respects they approach the tail-coverts of the peacock. +Now in P. malaccense, the two central tail-feathers alone are ornamented, +each with two brightly-coloured ocelli, the inner ocellus having completely +disappeared from all the other tail-feathers. Consequently the tail- +coverts and tail-feathers of this species of Polyplectron make a near +approach in structure and ornamentation to the corresponding feathers of +the peacock. + +As far, then, as gradation throws light on the steps by which the +magnificent train of the peacock has been acquired, hardly anything more is +needed. If we picture to ourselves a progenitor of the peacock in an +almost exactly intermediate condition between the existing peacock, with +his enormously elongated tail-coverts, ornamented with single ocelli, and +an ordinary gallinaceous bird with short tail-coverts, merely spotted with +some colour, we shall see a bird allied to Polyplectron--that is, with +tail-coverts, capable of erection and expansion, ornamented with two +partially confluent ocelli, and long enough almost to conceal the tail- +feathers, the latter having already partially lost their ocelli. The +indentation of the central disc and of the surrounding zones of the +ocellus, in both species of peacock, speaks plainly in favour of this view, +and is otherwise inexplicable. The males of Polyplectron are no doubt +beautiful birds, but their beauty, when viewed from a little distance, +cannot be compared with that of the peacock. Many female progenitors of +the peacock must, during a long line of descent, have appreciated this +superiority; for they have unconsciously, by the continued preference for +the most beautiful males, rendered the peacock the most splendid of living +birds. + +ARGUS PHEASANT. + +Another excellent case for investigation is offered by the ocelli on the +wing-feathers of the Argus pheasant, which are shaded in so wonderful a +manner as to resemble balls lying loose within sockets, and consequently +differ from ordinary ocelli. No one, I presume, will attribute the +shading, which has excited the admiration of many experienced artists, to +chance--to the fortuitous concourse of atoms of colouring matter. That +these ornaments should have been formed through the selection of many +successive variations, not one of which was originally intended to produce +the ball-and-socket effect, seems as incredible as that one of Raphael's +Madonnas should have been formed by the selection of chance daubs of paint +made by a long succession of young artists, not one of whom intended at +first to draw the human figure. In order to discover how the ocelli have +been developed, we cannot look to a long line of progenitors, nor to many +closely-allied forms, for such do not now exist. But fortunately the +several feathers on the wing suffice to give us a clue to the problem, and +they prove to demonstration that a gradation is at least possible from a +mere spot to a finished ball-and-socket ocellus. + +[Fig. 57. Part of secondary wing-feather of Argus pheasant, shewing two +perfect ocelli, a and b. A, B, C, D, etc., are dark stripes running +obliquely down, each to an ocellus. +[Much of the web on both sides, especially to the left of the shaft, has +been cut off.] + +Fig.59. Portion of one of the secondary wing-feathers near to the body, +shewing the so-called elliptic ornaments. The right-hand figure is given +merely as a diagram for the sake of the letters of reference. +A, B, C, D, etc. Rows of spots running down to and forming the elliptic +ornaments. +b. Lowest spot or mark in row B. +c. The next succeeding spot or mark in the same row. +d. Apparently a broken prolongation of the spot c. in the same row B.] + +The wing-feathers, bearing the ocelli, are covered with dark stripes (Fig. +57) or with rows of dark spots (Fig. 59), each stripe or row of spots +running obliquely down the outer side of the shaft to one of the ocelli. +The spots are generally elongated in a line transverse to the row in which +they stand. They often become confluent either in the line of the row--and +then they form a longitudinal stripe--or transversely, that is, with the +spots in the adjoining rows, and then they form transverse stripes. A spot +sometimes breaks up into smaller spots, which still stand in their proper +places. + +It will be convenient first to describe a perfect ball-and-socket ocellus. +This consists of an intensely black circular ring, surrounding a space +shaded so as exactly to resemble a ball. The figure here given has been +admirably drawn by Mr. Ford and well engraved, but a woodcut cannot exhibit +the exquisite shading of the original. The ring is almost always slightly +broken or interrupted (Fig. 57) at a point in the upper half, a little to +the right of and above the white shade on the enclosed ball; it is also +sometimes broken towards the base on the right hand. These little breaks +have an important meaning. The ring is always much thickened, with the +edges ill-defined towards the left-hand upper corner, the feather being +held erect, in the position in which it is here drawn. Beneath this +thickened part there is on the surface of the ball an oblique almost pure- +white mark, which shades off downwards into a pale-leaden hue, and this +into yellowish and brown tints, which insensibly become darker and darker +towards the lower part of the ball. It is this shading which gives so +admirably the effect of light shining on a convex surface. If one of the +balls be examined, it will be seen that the lower part is of a brown tint +and is indistinctly separated by a curved oblique line from the upper part, +which is yellower and more leaden; this curved oblique line runs at right +angles to the longer axis of the white patch of light, and indeed of all +the shading; but this difference in colour, which cannot of course be shewn +in the woodcut, does not in the least interfere with the perfect shading of +the ball. It should be particularly observed that each ocellus stands in +obvious connection either with a dark stripe, or with a longitudinal row of +dark spots, for both occur indifferently on the same feather. Thus in Fig. +57 stripe A runs to ocellus a; B runs to ocellus b; stripe C is broken in +the upper part, and runs down to the next succeeding ocellus, not +represented in the woodcut; D to the next lower one, and so with the +stripes E and F. Lastly, the several ocelli are separated from each other +by a pale surface bearing irregular black marks. + +[Fig. 58. Basal part of the secondary wing feather, nearest to the body.] + +I will next describe the other extreme of the series, namely, the first +trace of an ocellus. The short secondary wing-feather (Fig. 58), nearest +to the body, is marked like the other feathers, with oblique, longitudinal, +rather irregular, rows of very dark spots. The basal spot, or that nearest +the shaft, in the five lower rows (excluding the lowest one) is a little +larger than the other spots of the same row, and a little more elongated in +a transverse direction. It differs also from the other spots by being +bordered on its upper side with some dull fulvous shading. But this spot +is not in any way more remarkable than those on the plumage of many birds, +and might easily be overlooked. The next higher spot does not differ at +all from the upper ones in the same row. The larger basal spots occupy +exactly the same relative position on these feathers as do the perfect +ocelli on the longer wing-feathers. + +By looking to the next two or three succeeding wing-feathers, an absolutely +insensible gradation can be traced from one of the last-described basal +spots, together with the next higher one in the same row, to a curious +ornament, which cannot be called an ocellus, and which I will name, from +the want of a better term, an "elliptic ornament." These are shewn in the +accompanying figure (Fig. 59). We here see several oblique rows, A, B, C, +D, etc. (see the lettered diagram on the right hand), of dark spots of the +usual character. Each row of spots runs down to and is connected with one +of the elliptic ornaments, in exactly the same manner as each stripe in +Fig. 57 runs down to and is connected with one of the ball-and-socket +ocelli. Looking to any one row, for instance, B, in Fig. 59, the lowest +mark (b) is thicker and considerably longer than the upper spots, and has +its left extremity pointed and curved upwards. This black mark is abruptly +bordered on its upper side by a rather broad space of richly shaded tints, +beginning with a narrow brown zone, which passes into orange, and this into +a pale leaden tint, with the end towards the shaft much paler. These +shaded tints together fill up the whole inner space of the elliptic +ornament. The mark (b) corresponds in every respect with the basal shaded +spot of the simple feather described in the last paragraph (Fig. 58), but +is more highly developed and more brightly coloured. Above and to the +right of this spot (b, Fig. 59), with its bright shading, there is a long +narrow, black mark (c), belonging to the same row, and which is arched a +little downwards so as to face (b). This mark is sometimes broken into two +portions. It is also narrowly edged on the lower side with a fulvous tint. +To the left of and above c, in the same oblique direction, but always more +or less distinct from it, there is another black mark (d). This mark is +generally sub-triangular and irregular in shape, but in the one lettered in +the diagram it is unusually narrow, elongated, and regular. It apparently +consists of a lateral and broken prolongation of the mark (c), together +with its confluence with a broken and prolonged part of the next spot +above; but I do not feel sure of this. These three marks, b, c, and d, +with the intervening bright shades, form together the so-called elliptic +ornament. These ornaments placed parallel to the shaft, manifestly +correspond in position with the ball-and-socket ocelli. Their extremely +elegant appearance cannot be appreciated in the drawing, as the orange and +leaden tints, contrasting so well with the black marks, cannot be shewn. + +[Fig. 60. An ocellus in an intermediate condition between the elliptic +ornament and the perfect ball-and-socket ocellus.] + +Between one of the elliptic ornaments and a perfect ball-and-socket +ocellus, the gradation is so perfect that it is scarcely possible to decide +when the latter term ought to be used. The passage from the one into the +other is effected by the elongation and greater curvature in opposite +directions of the lower black mark (b, Fig. 59), and more especially of the +upper one (c), together with the contraction of the elongated sub- +triangular or narrow mark (d), so that at last these three marks become +confluent, forming an irregular elliptic ring. This ring is gradually +rendered more and more circular and regular, increasing at the same time in +diameter. I have here given a drawing (Fig. 60) of the natural size of an +ocellus not as yet quite perfect. The lower part of the black ring is much +more curved than is the lower mark in the elliptic ornament (b, Fig. 59). +The upper part of the ring consists of two or three separate portions; and +there is only a trace of the thickening of the portion which forms the +black mark above the white shade. This white shade itself is not as yet +much concentrated; and beneath it the surface is brighter coloured than in +a perfect ball-and-socket ocellus. Even in the most perfect ocelli traces +of the junction of three or four elongated black marks, by which the ring +has been formed, may often be detected. The irregular sub-triangular or +narrow mark (d, Fig. 59), manifestly forms, by its contraction and +equalisation, the thickened portion of the ring above the white shade on a +perfect ball-and-socket ocellus. The lower part of the ring is invariably +a little thicker than the other parts (Fig. 57), and this follows from the +lower black mark of the elliptic ornament (b, Fig. 59) having originally +been thicker than the upper mark (c). Every step can be followed in the +process of confluence and modification; and the black ring which surrounds +the ball of the ocellus is unquestionably formed by the union and +modification of the three black marks, b, c, d, of the elliptic ornament. +The irregular zigzag black marks between the successive ocelli (Fig. 57) +are plainly due to the breaking up of the somewhat more regular but similar +marks between the elliptic ornaments. + +The successive steps in the shading of the ball-and-socket ocelli can be +followed out with equal clearness. The brown, orange, and pale-leadened +narrow zones, which border the lower black mark of the elliptic ornament, +can be seen gradually to become more and more softened and shaded into each +other, with the upper lighter part towards the left-hand corner rendered +still lighter, so as to become almost white, and at the same time more +contracted. But even in the most perfect ball-and-socket ocelli a slight +difference in the tints, though not in the shading, between the upper and +lower parts of the ball can be perceived, as before noticed; and the line +of separation is oblique, in the same direction as the bright coloured +shades of the elliptic ornaments. Thus almost every minute detail in the +shape and colouring of the ball-and-socket ocelli can be shewn to follow +from gradual changes in the elliptic ornaments; and the development of the +latter can be traced by equally small steps from the union of two almost +simple spots, the lower one (Fig. 58) having some dull fulvous shading on +its upper side. + +[Fig. 61. Portion near summit of one of the secondary wing-feathers, +bearing perfect ball-and-socket ocelli. +a. Ornamented upper part. +b. Uppermost, imperfect ball-and-socket ocellus. (The shading above the +white mark on the summit of the ocellus is here a little too dark.) +c. Perfect ocellus.] + +The extremities of the longer secondary feathers which bear the perfect +ball-and-socket ocelli, are peculiarly ornamented (Fig. 61). The oblique +longitudinal stripes suddenly cease upwards and become confused; and above +this limit the whole upper end of the feather (a) is covered with white +dots, surrounded by little black rings, standing on a dark ground. The +oblique stripe belonging to the uppermost ocellus (b) is barely represented +by a very short irregular black mark with the usual, curved, transverse +base. As this stripe is thus abruptly cut off, we can perhaps understand +from what has gone before, how it is that the upper thickened part of the +ring is here absent; for, as before stated, this thickened part apparently +stands in some relation with a broken prolongation from the next higher +spot. From the absence of the upper and thickened part of the ring, the +uppermost ocellus, though perfect in all other respects, appears as if its +top had been obliquely sliced off. It would, I think, perplex any one, who +believes that the plumage of the Argus pheasant was created as we now see +it, to account for the imperfect condition of the uppermost ocellus. I +should add that on the secondary wing-feather farthest from the body all +the ocelli are smaller and less perfect than on the other feathers, and +have the upper part of the ring deficient, as in the case just mentioned. +The imperfection here seems to be connected with the fact that the spots on +this feather shew less tendency than usual to become confluent into +stripes; they are, on the contrary, often broken up into smaller spots, so +that two or three rows run down to the same ocellus. + +There still remains another very curious point, first observed by Mr. T.W. +Wood (51. The 'Field,' May 28, 1870.), which deserves attention. In a +photograph, given me by Mr. Ward, of a specimen mounted as in the act of +display, it may be seen that on the feathers which are held +perpendicularly, the white marks on the ocelli, representing light +reflected from a convex surface, are at the upper or further end, that is, +are directed upwards; and the bird whilst displaying himself on the ground +would naturally be illuminated from above. But here comes the curious +point; the outer feathers are held almost horizontally, and their ocelli +ought likewise to appear as if illuminated from above, and consequently the +white marks ought to be placed on the upper sides of the ocelli; and, +wonderful as is the fact, they are thus placed! Hence the ocelli on the +several feathers, though occupying very different positions with respect to +the light, all appear as if illuminated from above, just as an artist would +have shaded them. Nevertheless they are not illuminated from strictly the +same point as they ought to be; for the white marks on the ocelli of the +feathers which are held almost horizontally, are placed rather too much +towards the further end; that is, they are not sufficiently lateral. We +have, however, no right to expect absolute perfection in a part rendered +ornamental through sexual selection, any more than we have in a part +modified through natural selection for real use; for instance, in that +wondrous organ the human eye. And we know what Helmholtz, the highest +authority in Europe on the subject, has said about the human eye; that if +an optician had sold him an instrument so carelessly made, he would have +thought himself fully justified in returning it. (52. 'Popular Lectures +on Scientific Subjects,' Eng. trans. 1873, pp. 219, 227, 269, 390.) + +We have now seen that a perfect series can be followed, from simple spots +to the wonderful ball-and-socket ornaments. Mr. Gould, who kindly gave me +some of these feathers, fully agrees with me in the completeness of the +gradation. It is obvious that the stages in development exhibited by the +feathers on the same bird do not at all necessarily shew us the steps +passed through by the extinct progenitors of the species; but they probably +give us the clue to the actual steps, and they at least prove to +demonstration that a gradation is possible. Bearing in mind how carefully +the male Argus pheasant displays his plumes before the female, as well as +the many facts rendering it probable that female birds prefer the more +attractive males, no one who admits the agency of sexual selection in any +case will deny that a simple dark spot with some fulvous shading might be +converted, through the approximation and modification of two adjoining +spots, together with some slight increase of colour, into one of the so- +called elliptic ornaments. These latter ornaments have been shewn to many +persons, and all have admitted that they are beautiful, some thinking them +even more so than the ball-and-socket ocelli. As the secondary plumes +became lengthened through sexual selection, and as the elliptic ornaments +increased in diameter, their colours apparently became less bright; and +then the ornamentation of the plumes had to be gained by an improvement in +the pattern and shading; and this process was carried on until the +wonderful ball-and-socket ocelli were finally developed. Thus we can +understand--and in no other way as it seems to me--the present condition +and origin of the ornaments on the wing-feathers of the Argus pheasant. + +From the light afforded by the principle of gradation--from what we know of +the laws of variation--from the changes which have taken place in many of +our domesticated birds--and, lastly, from the character (as we shall +hereafter see more clearly) of the immature plumage of young birds--we can +sometimes indicate, with a certain amount of confidence, the probable steps +by which the males have acquired their brilliant plumage and various +ornaments; yet in many cases we are involved in complete darkness. Mr. +Gould several years ago pointed out to me a humming-bird, the Urosticte +benjamini, remarkable for the curious differences between the sexes. The +male, besides a splendid gorget, has greenish-black tail-feathers, with the +four CENTRAL ones tipped with white; in the female, as with most of the +allied species, the three OUTER tail-feathers on each side are tipped with +white, so that the male has the four central, whilst the female has the six +exterior feathers ornamented with white tips. What makes the case more +curious is that, although the colouring of the tail differs remarkably in +both sexes of many kinds of humming-birds, Mr. Gould does not know a single +species, besides the Urosticte, in which the male has the four central +feathers tipped with white. + +The Duke of Argyll, in commenting on this case (53. 'The Reign of Law,' +1867, p. 247.), passes over sexual selection, and asks, "What explanation +does the law of natural selection give of such specific varieties as +these?" He answers "none whatever"; and I quite agree with him. But can +this be so confidently said of sexual selection? Seeing in how many ways +the tail-feathers of humming-birds differ, why should not the four central +feathers have varied in this one species alone, so as to have acquired +white tips? The variations may have been gradual, or somewhat abrupt as in +the case recently given of the humming-birds near Bogota, in which certain +individuals alone have the "central tail-feathers tipped with beautiful +green." In the female of the Urosticte I noticed extremely minute or +rudimental white tips to the two outer of the four central black tail- +feathers; so that here we have an indication of change of some kind in the +plumage of this species. If we grant the possibility of the central tail- +feathers of the male varying in whiteness, there is nothing strange in such +variations having been sexually selected. The white tips, together with +the small white ear-tufts, certainly add, as the Duke of Argyll admits, to +the beauty of the male; and whiteness is apparently appreciated by other +birds, as may be inferred from such cases as the snow-white male of the +Bell-bird. The statement made by Sir R. Heron should not be forgotten, +namely, that his peahens, when debarred from access to the pied peacock, +would not unite with any other male, and during that season produced no +offspring. Nor is it strange that variations in the tail-feathers of the +Urosticte should have been specially selected for the sake of ornament, for +the next succeeding genus in the family takes its name of Metallura from +the splendour of these feathers. We have, moreover, good evidence that +humming-birds take especial pains in displaying their tail-feathers; Mr. +Belt (54. 'The Naturalist in Nicaragua,' 1874, p. 112.), after describing +the beauty of the Florisuga mellivora, says, "I have seen the female +sitting on a branch, and two males displaying their charms in front of her. +One would shoot up like a rocket, then suddenly expanding the snow-white +tail, like an inverted parachute, slowly descend in front of her, turning +round gradually to shew off back and front...The expanded white tail +covered more space than all the rest of the bird, and was evidently the +grand feature in the performance. Whilst one male was descending, the +other would shoot up and come slowly down expanded. The entertainment +would end in a fight between the two performers; but whether the most +beautiful or the most pugnacious was the accepted suitor, I know not." Mr. +Gould, after describing the peculiar plumage of the Urosticte, adds, "that +ornament and variety is the sole object, I have myself but little doubt." +(55. 'Introduction to the Trochilidae,' 1861, p. 110.) If this be +admitted, we can perceive that the males which during former times were +decked in the most elegant and novel manner would have gained an advantage, +not in the ordinary struggle for life, but in rivalry with other males, and +would have left a larger number of offspring to inherit their newly- +acquired beauty. + + +CHAPTER XV. + +Birds--continued. + +Discussion as to why the males alone of some species, and both sexes of +others, are brightly coloured--On sexually-limited inheritance, as applied +to various structures and to brightly-coloured plumage--Nidification in +relation to colour--Loss of nuptial plumage during the winter. + +We have in this chapter to consider why the females of many birds have not +acquired the same ornaments as the male; and why, on the other hand, both +sexes of many other birds are equally, or almost equally, ornamented? In +the following chapter we shall consider the few cases in which the female +is more conspicuously coloured than the male. + +In my 'Origin of Species' (1. Fourth edition, 1866, p. 241.) I briefly +suggested that the long tail of the peacock would be inconvenient and the +conspicuous black colour of the male capercailzie dangerous, to the female +during the period of incubation: and consequently that the transmission of +these characters from the male to the female offspring had been checked +through natural selection. I still think that this may have occurred in +some few instances: but after mature reflection on all the facts which I +have been able to collect, I am now inclined to believe that when the sexes +differ, the successive variations have generally been from the first +limited in their transmission to the same sex in which they first arose. +Since my remarks appeared, the subject of sexual coloration has been +discussed in some very interesting papers by Mr. Wallace (2. 'Westminster +Review,' July 1867. 'Journal of Travel,' vol. i. 1868, p. 73.), who +believes that in almost all cases the successive variations tended at first +to be transmitted equally to both sexes; but that the female was saved, +through natural selection, from acquiring the conspicuous colours of the +male, owing to the danger which she would thus have incurred during +incubation. + +This view necessitates a tedious discussion on a difficult point, namely, +whether the transmission of a character, which is at first inherited by +both sexes can be subsequently limited in its transmission to one sex alone +by means of natural selection. We must bear in mind, as shewn in the +preliminary chapter on sexual selection, that characters which are limited +in their development to one sex are always latent in the other. An +imaginary illustration will best aid us in seeing the difficulty of the +case; we may suppose that a fancier wished to make a breed of pigeons, in +which the males alone should be coloured of a pale blue, whilst the females +retained their former slaty tint. As with pigeons characters of all kinds +are usually transmitted to both sexes equally, the fancier would have to +try to convert this latter form of inheritance into sexually-limited +transmission. All that he could do would be to persevere in selecting +every male pigeon which was in the least degree of a paler blue; and the +natural result of this process, if steadily carried on for a long time, and +if the pale variations were strongly inherited or often recurred, would be +to make his whole stock of a lighter blue. But our fancier would be +compelled to match, generation after generation, his pale blue males with +slaty females, for he wishes to keep the latter of this colour. The result +would generally be the production either of a mongrel piebald lot, or more +probably the speedy and complete loss of the pale-blue tint; for the +primordial slaty colour would be transmitted with prepotent force. +Supposing, however, that some pale-blue males and slaty females were +produced during each successive generation, and were always crossed +together, then the slaty females would have, if I may use the expression, +much blue blood in their veins, for their fathers, grandfathers, etc., will +all have been blue birds. Under these circumstances it is conceivable +(though I know of no distinct facts rendering it probable) that the slaty +females might acquire so strong a latent tendency to pale-blueness, that +they would not destroy this colour in their male offspring, their female +offspring still inheriting the slaty tint. If so, the desired end of +making a breed with the two sexes permanently different in colour might be +gained. + +The extreme importance, or rather necessity in the above case of the +desired character, namely, pale-blueness, being present though in a latent +state in the female, so that the male offspring should not be deteriorated, +will be best appreciated as follows: the male of Soemmerring's pheasant +has a tail thirty-seven inches in length, whilst that of the female is only +eight inches; the tail of the male common pheasant is about twenty inches, +and that of the female twelve inches long. Now if the female Soemmerring +pheasant with her SHORT tail were crossed with the male common pheasant, +there can be no doubt that the male hybrid offspring would have a much +LONGER tail than that of the pure offspring of the common pheasant. On the +other hand, if the female common pheasant, with a tail much longer than +that of the female Soemmerring pheasant, were crossed with the male of the +latter, the male hybrid offspring would have a much SHORTER tail than that +of the pure offspring of Soemmerring's pheasant. (3. Temminck says that +the tail of the female Phasianus Soemmerringii is only six inches long, +'Planches coloriees,' vol. v. 1838, pp. 487 and 488: the measurements +above given were made for me by Mr. Sclater. For the common pheasant, see +Macgillivray, 'History of British Birds,' vol. i. pp. 118-121.) + +Our fancier, in order to make his new breed with the males of a pale-blue +tint, and the females unchanged, would have to continue selecting the males +during many generations; and each stage of paleness would have to be fixed +in the males, and rendered latent in the females. The task would be an +extremely difficult one, and has never been tried, but might possibly be +successfully carried out. The chief obstacle would be the early and +complete loss of the pale-blue tint, from the necessity of reiterated +crosses with the slaty female, the latter not having at first any LATENT +tendency to produce pale-blue offspring. + +On the other hand, if one or two males were to vary ever so slightly in +paleness, and the variations were from the first limited in their +transmission to the male sex, the task of making a new breed of the desired +kind would be easy, for such males would simply have to be selected and +matched with ordinary females. An analogous case has actually occurred, +for there are breeds of the pigeon in Belgium (4. Dr. Chapuis, 'Le Pigeon +Voyageur Belge,' 1865, p. 87.) in which the males alone are marked with +black striae. So again Mr. Tegetmeier has recently shewn (5. The 'Field,' +Sept. 1872.) that dragons not rarely produce silver-coloured birds, which +are almost always hens; and he himself has bred ten such females. It is on +the other hand a very unusual event when a silver male is produced; so that +nothing would be easier, if desired, than to make a breed of dragons with +blue males and silver females. This tendency is indeed so strong that when +Mr. Tegetmeier at last got a silver male and matched him with one of the +silver females, he expected to get a breed with both sexes thus coloured; +he was however disappointed, for the young male reverted to the blue colour +of his grandfather, the young female alone being silver. No doubt with +patience this tendency to reversion in the males, reared from an occasional +silver male matched with a silver hen, might be eliminated, and then both +sexes would be coloured alike; and this very process has been followed with +success by Mr. Esquilant in the case of silver turbits. + +With fowls, variations of colour, limited in their transmission to the male +sex, habitually occur. When this form of inheritance prevails, it might +well happen that some of the successive variations would be transferred to +the female, who would then slightly resemble the male, as actually occurs +in some breeds. Or again, the greater number, but not all, of the +successive steps might be transferred to both sexes, and the female would +then closely resemble the male. There can hardly be a doubt that this is +the cause of the male pouter pigeon having a somewhat larger crop, and of +the male carrier pigeon having somewhat larger wattles, than their +respective females; for fanciers have not selected one sex more than the +other, and have had no wish that these characters should be more strongly +displayed in the male than in the female, yet this is the case with both +breeds. + +The same process would have to be followed, and the same difficulties +encountered, if it were desired to make a breed with the females alone of +some new colour. + +Lastly, our fancier might wish to make a breed with the two sexes differing +from each other, and both from the parent species. Here the difficulty +would be extreme, unless the successive variations were from the first +sexually limited on both sides, and then there would be no difficulty. We +see this with the fowl; thus the two sexes of the pencilled Hamburghs +differ greatly from each other, and from the two sexes of the aboriginal +Gallus bankiva; and both are now kept constant to their standard of +excellence by continued selection, which would be impossible unless the +distinctive characters of both were limited in their transmission. + +The Spanish fowl offers a more curious case; the male has an immense comb, +but some of the successive variations, by the accumulation of which it was +acquired, appear to have been transferred to the female; for she has a comb +many times larger than that of the females of the parent species. But the +comb of the female differs in one respect from that of the male, for it is +apt to lop over; and within a recent period it has been ordered by the +fancy that this should always be the case, and success has quickly followed +the order. Now the lopping of the comb must be sexually limited in its +transmission, otherwise it would prevent the comb of the male from being +perfectly upright, which would be abhorrent to every fancier. On the other +hand, the uprightness of the comb in the male must likewise be a sexually- +limited character, otherwise it would prevent the comb of the female from +lopping over. + +From the foregoing illustrations, we see that even with almost unlimited +time at command, it would be an extremely difficult and complex, perhaps an +impossible process, to change one form of transmission into the other +through selection. Therefore, without distinct evidence in each case, I am +unwilling to admit that this has been effected in natural species. On the +other hand, by means of successive variations, which were from the first +sexually limited in their transmission, there would not be the least +difficulty in rendering a male bird widely different in colour or in any +other character from the female; the latter being left unaltered, or +slightly altered, or specially modified for the sake of protection. + +As bright colours are of service to the males in their rivalry with other +males, such colours would be selected whether or not they were transmitted +exclusively to the same sex. Consequently the females might be expected +often to partake of the brightness of the males to a greater or less +degree; and this occurs with a host of species. If all the successive +variations were transmitted equally to both sexes, the females would be +indistinguishable from the males; and this likewise occurs with many birds. +If, however, dull colours were of high importance for the safety of the +female during incubation, as with many ground birds, the females which +varied in brightness, or which received through inheritance from the males +any marked accession of brightness, would sooner or later be destroyed. +But the tendency in the males to continue for an indefinite period +transmitting to their female offspring their own brightness, would have to +be eliminated by a change in the form of inheritance; and this, as shewn by +our previous illustration, would be extremely difficult. The more probable +result of the long-continued destruction of the more brightly-coloured +females, supposing the equal form of transmission to prevail, would be the +lessening or annihilation of the bright colours of the males, owing to +their continual crossing with the duller females. It would be tedious to +follow out all the other possible results; but I may remind the reader that +if sexually-limited variations in brightness occurred in the females, even +if they were not in the least injurious to them and consequently were not +eliminated, yet they would not be favoured or selected, for the male +usually accepts any female, and does not select the more attractive +individuals; consequently these variations would be liable to be lost, and +would have little influence on the character of the race; and this will aid +in accounting for the females being commonly duller-coloured than the +males. + +In the eighth chapter instances were given, to which many might here be +added, of variations occurring at various ages, and inherited at the +corresponding age. It was also shewn that variations which occur late in +life are commonly transmitted to the same sex in which they first appear; +whilst variations occurring early in life are apt to be transmitted to both +sexes; not that all the cases of sexually-limited transmission can thus be +accounted for. It was further shewn that if a male bird varied by becoming +brighter whilst young, such variations would be of no service until the age +for reproduction had arrived, and there was competition between rival +males. But in the case of birds living on the ground and commonly in need +of the protection of dull colours, bright tints would be far more dangerous +to the young and inexperienced than to the adult males. Consequently the +males which varied in brightness whilst young would suffer much destruction +and be eliminated through natural selection; on the other hand, the males +which varied in this manner when nearly mature, notwithstanding that they +were exposed to some additional danger, might survive, and from being +favoured through sexual selection, would procreate their kind. As a +relation often exists between the period of variation and the form of +transmission, if the bright-coloured young males were destroyed and the +mature ones were successful in their courtship, the males alone would +acquire brilliant colours and would transmit them exclusively to their male +offspring. But I by no means wish to maintain that the influence of age on +the form of transmission, is the sole cause of the great difference in +brilliancy between the sexes of many birds. + +When the sexes of birds differ in colour, it is interesting to determine +whether the males alone have been modified by sexual selection, the females +having been left unchanged, or only partially and indirectly thus changed; +or whether the females have been specially modified through natural +selection for the sake of protection. I will therefore discuss this +question at some length, even more fully than its intrinsic importance +deserves; for various curious collateral points may thus be conveniently +considered. + +Before we enter on the subject of colour, more especially in reference to +Mr. Wallace's conclusions, it may be useful to discuss some other sexual +differences under a similar point of view. A breed of fowls formerly +existed in Germany (6. Bechstein, 'Naturgeschichte Deutschlands,' 1793, B. +iii. 339.) in which the hens were furnished with spurs; they were good +layers, but they so greatly disturbed their nests with their spurs that +they could not be allowed to sit on their own eggs. Hence at one time it +appeared to me probable that with the females of the wild Gallinaceae the +development of spurs had been checked through natural selection, from the +injury thus caused to their nests. This seemed all the more probable, as +wing-spurs, which would not be injurious during incubation, are often as +well-developed in the female as in the male; though in not a few cases they +are rather larger in the male. When the male is furnished with leg-spurs +the female almost always exhibits rudiments of them,--the rudiment +sometimes consisting of a mere scale, as in Gallus. Hence it might be +argued that the females had aboriginally been furnished with well-developed +spurs, but that these had subsequently been lost through disuse or natural +selection. But if this view be admitted, it would have to be extended to +innumerable other cases; and it implies that the female progenitors of the +existing spur-bearing species were once encumbered with an injurious +appendage. + +In some few genera and species, as in Galloperdix, Acomus, and the Javan +peacock (Pavo muticus), the females, as well as the males, possess well- +developed leg-spurs. Are we to infer from this fact that they construct a +different sort of nest from that made by their nearest allies, and not +liable to be injured by their spurs; so that the spurs have not been +removed? Or are we to suppose that the females of these several species +especially require spurs for their defence? It is a more probable +conclusion that both the presence and absence of spurs in the females +result from different laws of inheritance having prevailed, independently +of natural selection. With the many females in which spurs appear as +rudiments, we may conclude that some few of the successive variations, +through which they were developed in the males, occurred very early in +life, and were consequently transferred to the females. In the other and +much rarer cases, in which the females possess fully developed spurs, we +may conclude that all the successive variations were transferred to them; +and that they gradually acquired and inherited the habit of not disturbing +their nests. + +The vocal organs and the feathers variously modified for producing sound, +as well as the proper instincts for using them, often differ in the two +sexes, but are sometimes the same in both. Can such differences be +accounted for by the males having acquired these organs and instincts, +whilst the females have been saved from inheriting them, on account of the +danger to which they would have been exposed by attracting the attention of +birds or beasts of prey? This does not seem to me probable, when we think +of the multitude of birds which with impunity gladden the country with +their voices during the spring. (7. Daines Barrington, however, thought +it probable ('Philosophical Transactions,' 1773, p. 164) that few female +birds sing, because the talent would have been dangerous to them during +incubation. He adds, that a similar view may possibly account for the +inferiority of the female to the male in plumage.) It is a safer +conclusion that, as vocal and instrumental organs are of special service +only to the males during their courtship, these organs were developed +through sexual selection and their constant use in that sex alone--the +successive variations and the effects of use having been from the first +more or less limited in transmission to the male offspring. + +Many analogous cases could be adduced; those for instance of the plumes on +the head being generally longer in the male than in the female, sometimes +of equal length in both sexes, and occasionally absent in the female,-- +these several cases occurring in the same group of birds. It would be +difficult to account for such a difference between the sexes by the female +having been benefited by possessing a slightly shorter crest than the male, +and its consequent diminution or complete suppression through natural +selection. But I will take a more favourable case, namely the length of +the tail. The long train of the peacock would have been not only +inconvenient but dangerous to the peahen during the period of incubation +and whilst accompanying her young. Hence there is not the least a priori +improbability in the development of her tail having been checked through +natural selection. But the females of various pheasants, which apparently +are exposed on their open nests to as much danger as the peahen, have tails +of considerable length. The females as well as the males of the Menura +superba have long tails, and they build a domed nest, which is a great +anomaly in so large a bird. Naturalists have wondered how the female +Menura could manage her tail during incubation; but it is now known (8. +Mr. Ramsay, in 'Proc. Zoolog. Soc.' 1868, p. 50.) that she "enters the nest +head first, and then turns round with her tail sometimes over her back, but +more often bent round by her side. Thus in time the tail becomes quite +askew, and is a tolerable guide to the length of time the bird has been +sitting." Both sexes of an Australian kingfisher (Tanysiptera sylvia) have +the middle tail-feathers greatly lengthened, and the female makes her nest +in a hole; and as I am informed by Mr. R.B. Sharpe these feathers become +much crumpled during incubation. + +In these two latter cases the great length of the tail-feathers must be in +some degree inconvenient to the female; and as in both species the tail- +feathers of the female are somewhat shorter than those of the male, it +might be argued that their full development had been prevented through +natural selection. But if the development of the tail of the peahen had +been checked only when it became inconveniently or dangerously great, she +would have retained a much longer tail than she actually possesses; for her +tail is not nearly so long, relatively to the size of her body, as that of +many female pheasants, nor longer than that of the female turkey. It must +also be borne in mind that, in accordance with this view, as soon as the +tail of the peahen became dangerously long, and its development was +consequently checked, she would have continually reacted on her male +progeny, and thus have prevented the peacock from acquiring his present +magnificent train. We may therefore infer that the length of the tail in +the peacock and its shortness in the peahen are the result of the requisite +variations in the male having been from the first transmitted to the male +offspring alone. + +We are led to a nearly similar conclusion with respect to the length of the +tail in the various species of pheasants. In the Eared pheasant +(Crossoptilon auritum) the tail is of equal length in both sexes, namely +sixteen or seventeen inches; in the common pheasant it is about twenty +inches long in the male and twelve in the female; in Soemmerring's +pheasant, thirty-seven inches in the male and only eight in the female; and +lastly in Reeve's pheasant it is sometimes actually seventy-two inches long +in the male and sixteen in the female. Thus in the several species, the +tail of the female differs much in length, irrespectively of that of the +male; and this can be accounted for, as it seems to me, with much more +probability, by the laws of inheritance,--that is by the successive +variations having been from the first more or less closely limited in their +transmission to the male sex than by the agency of natural selection, +resulting from the length of tail being more or less injurious to the +females of these several allied species. + +We may now consider Mr. Wallace's arguments in regard to the sexual +coloration of birds. He believes that the bright tints originally acquired +through sexual selection by the males would in all, or almost all cases, +have been transmitted to the females, unless the transference had been +checked through natural selection. I may here remind the reader that +various facts opposed to this view have already been given under reptiles, +amphibians, fishes and lepidoptera. Mr. Wallace rests his belief chiefly, +but not exclusively, as we shall see in the next chapter, on the following +statement (9. 'Journal of Travel,' edited by A. Murray, vol. i. 1868, p. +78.), that when both sexes are coloured in a very conspicuous manner, the +nest is of such a nature as to conceal the sitting bird; but when there is +a marked contrast of colour between the sexes, the male being gay and the +female dull-coloured, the nest is open and exposes the sitting bird to +view. This coincidence, as far as it goes, certainly seems to favour the +belief that the females which sit on open nests have been specially +modified for the sake of protection; but we shall presently see that there +is another and more probable explanation, namely, that conspicuous females +have acquired the instinct of building domed nests oftener than dull- +coloured birds. Mr. Wallace admits that there are, as might have been +expected, some exceptions to his two rules, but it is a question whether +the exceptions are not so numerous as seriously to invalidate them. + +There is in the first place much truth in the Duke of Argyll's remark (10. +'Journal of Travel,' edited by A. Murray, vol. i. 1868, p. 281.) that a +large domed nest is more conspicuous to an enemy, especially to all tree- +haunting carnivorous animals, than a smaller open nest. Nor must we forget +that with many birds which build open nests, the male sits on the eggs and +aids the female in feeding the young: this is the case, for instance, with +Pyranga aestiva (11. Audubon, 'Ornithological Biography,' vol. i. p. +233.), one of the most splendid birds in the United States, the male being +vermilion, and the female light brownish-green. Now if brilliant colours +had been extremely dangerous to birds whilst sitting on their open nests, +the males in these cases would have suffered greatly. It might, however, +be of such paramount importance to the male to be brilliantly coloured, in +order to beat his rivals, that this may have more than compensated some +additional danger. + +Mr. Wallace admits that with the King-crows (Dicrurus), Orioles, and +Pittidae, the females are conspicuously coloured, yet build open nests; but +he urges that the birds of the first group are highly pugnacious and could +defend themselves; that those of the second group take extreme care in +concealing their open nests, but this does not invariably hold good (12. +Jerdon, 'Birds of India,' vol. ii. p. 108. Gould's 'Handbook of the Birds +of Australia,' vol. i. p. 463.); and that with the birds of the third group +the females are brightly coloured chiefly on the under surface. Besides +these cases, pigeons which are sometimes brightly, and almost always +conspicuously coloured, and which are notoriously liable to the attacks of +birds of prey, offer a serious exception to the rule, for they almost +always build open and exposed nests. In another large family, that of the +humming-birds, all the species build open nests, yet with some of the most +gorgeous species the sexes are alike; and in the majority, the females, +though less brilliant than the males, are brightly coloured. Nor can it be +maintained that all female humming-birds, which are brightly coloured, +escape detection by their tints being green, for some display on their +upper surfaces red, blue, and other colours. (13. For instance, the +female Eupetomena macroura has the head and tail dark blue with reddish +loins; the female Lampornis porphyrurus is blackish-green on the upper +surface, with the lores and sides of the throat crimson; the female +Eulampis jugularis has the top of the head and back green, but the loins +and the tail are crimson. Many other instances of highly conspicuous +females could be given. See Mr. Gould's magnificent work on this family.) + +In regard to birds which build in holes or construct domed nests, other +advantages, as Mr. Wallace remarks, besides concealment are gained, such as +shelter from the rain, greater warmth, and in hot countries protection from +the sun (14. Mr. Salvin noticed in Guatemala ('Ibis,' 1864, p. 375) that +humming-birds were much more unwilling to leave their nests during very hot +weather, when the sun was shining brightly, as if their eggs would be thus +injured, than during cool, cloudy, or rainy weather.); so that it is no +valid objection to his view that many birds having both sexes obscurely +coloured build concealed nests. (15. I may specify, as instances of dull- +coloured birds building concealed nests, the species belonging to eight +Australian genera described in Gould's 'Handbook of the Birds of +Australia,' vol. i. pp. 340, 362, 365, 383, 387, 389, 391, 414.) The +female Horn-bill (Buceros), for instance, of India and Africa is protected +during incubation with extraordinary care, for she plasters up with her own +excrement the orifice of the hole in which she sits on her eggs, leaving +only a small orifice through which the male feeds her; she is thus kept a +close prisoner during the whole period of incubation (16. Mr. C. Horne, +'Proc. Zoolog. Soc.' 1869. p. 243.); yet female horn-bills are not more +conspicuously coloured than many other birds of equal size which build open +nests. It is a more serious objection to Mr. Wallace's view, as is +admitted by him, that in some few groups the males are brilliantly coloured +and the females obscure, and yet the latter hatch their eggs in domed +nests. This is the case with the Grallinae of Australia, the Superb +Warblers (Maluridae) of the same country, the Sun-birds (Nectariniae), and +with several of the Australian Honey-suckers or Meliphagidae. (17. On the +nidification and colours of these latter species, see Gould's 'Handbook to +the Birds of Australia,' vol. i. pp. 504, 527.) + +If we look to the birds of England we shall see that there is no close and +general relation between the colours of the female and the nature of the +nest which is constructed. About forty of our British birds (excluding +those of large size which could defend themselves) build in holes in banks, +rocks, or trees, or construct domed nests. If we take the colours of the +female goldfinch, bullfinch, or blackbird, as a standard of the degree of +conspicuousness, which is not highly dangerous to the sitting female, then +out of the above forty birds the females of only twelve can be considered +as conspicuous to a dangerous degree, the remaining twenty-eight being +inconspicuous. (18. I have consulted, on this subject, Macgillivray's +'British Birds,' and though doubts may be entertained in some cases in +regard to the degree of concealment of the nest, and to the degree of +conspicuousness of the female, yet the following birds, which all lay their +eggs in holes or in domed nests, can hardly be considered, by the above +standard, as conspicuous: Passer, 2 species; Sturnus, of which the female +is considerably less brilliant than the male; Cinclus; Motallica boarula +(?); Erithacus (?); Fruticola, 2 sp.; Saxicola; Ruticilla, 2 sp.; Sylvia, 3 +sp.; Parus, 3 sp.; Mecistura; Anorthura; Certhia; Sitta; Yunx; Muscicapa, 2 +sp.; Hirundo, 3 sp.; and Cypselus. The females of the following 12 birds +may be considered as conspicuous according to the same standard, viz., +Pastor, Motacilla alba, Parus major and P. caeruleus, Upupa, Picus, 4 sp., +Coracias, Alcedo, and Merops.) Nor is there any close relation within the +same genus between a well-pronounced difference in colour between the +sexes, and the nature of the nest constructed. Thus the male house sparrow +(Passer domesticus) differs much from the female, the male tree-sparrow (P. +montanus) hardly at all, and yet both build well-concealed nests. The two +sexes of the common fly-catcher (Muscicapa grisola) can hardly be +distinguished, whilst the sexes of the pied fly-catcher (M. luctuosa) +differ considerably, and both species build in holes or conceal their +nests. The female blackbird (Turdus merula) differs much, the female ring- +ouzel (T. torquatus) differs less, and the female common thrush (T. +musicus) hardly at all from their respective males; yet all build open +nests. On the other hand, the not very distantly-allied water-ouzel +(Cinclus aquaticus) builds a domed nest, and the sexes differ about as much +as in the ring-ouzel. The black and red grouse (Tetrao tetrix and T. +scoticus) build open nests in equally well-concealed spots, but in the one +species the sexes differ greatly, and in the other very little. + +Notwithstanding the foregoing objections, I cannot doubt, after reading Mr. +Wallace's excellent essay, that looking to the birds of the world, a large +majority of the species in which the females are conspicuously coloured +(and in this case the males with rare exceptions are equally conspicuous), +build concealed nests for the sake of protection. Mr. Wallace enumerates +(19. 'Journal of Travel,' edited by A. Murray, vol. i. p. 78.) a long +series of groups in which this rule holds good; but it will suffice here to +give, as instances, the more familiar groups of kingfishers, toucans, +trogons, puff-birds (Capitonidae), plantain-eaters (Musophagae, +woodpeckers, and parrots. Mr. Wallace believes that in these groups, as +the males gradually acquired through sexual selection their brilliant +colours, these were transferred to the females and were not eliminated by +natural selection, owing to the protection which they already enjoyed from +their manner of nidification. According to this view, their present manner +of nesting was acquired before their present colours. But it seems to me +much more probable that in most cases, as the females were gradually +rendered more and more brilliant from partaking of the colours of the male, +they were gradually led to change their instincts (supposing that they +originally built open nests), and to seek protection by building domed or +concealed nests. No one who studies, for instance, Audubon's account of +the differences in the nests of the same species in the Northern and +Southern United States (20. See many statements in the 'Ornithological +Biography.' See also some curious observations on the nests of Italian +birds by Eugenio Bettoni, in the 'Atti della Società Italiana,' vol. xi. +1869, p. 487.), will feel any great difficulty in admitting that birds, +either by a change (in the strict sense of the word) of their habits, or +through the natural selection of so-called spontaneous variations of +instinct, might readily be led to modify their manner of nesting. + +This way of viewing the relation, as far as it holds good, between the +bright colours of female birds and their manner of nesting, receives some +support from certain cases occurring in the Sahara Desert. Here, as in +most other deserts, various birds, and many other animals, have had their +colours adapted in a wonderful manner to the tints of the surrounding +surface. Nevertheless there are, as I am informed by the Rev. Mr. +Tristram, some curious exceptions to the rule; thus the male of the +Monticola cyanea is conspicuous from his bright blue colour, and the female +almost equally conspicuous from her mottled brown and white plumage; both +sexes of two species of Dromolaea are of a lustrous black; so that these +three species are far from receiving protection from their colours, yet +they are able to survive, for they have acquired the habit of taking refuge +from danger in holes or crevices in the rocks. + +With respect to the above groups in which the females are conspicuously +coloured and build concealed nests, it is not necessary to suppose that +each separate species had its nidifying instinct specially modified; but +only that the early progenitors of each group were gradually led to build +domed or concealed nests, and afterwards transmitted this instinct, +together with their bright colours, to their modified descendants. As far +as it can be trusted, the conclusion is interesting, that sexual selection +together with equal or nearly equal inheritance by both sexes, have +indirectly determined the manner of nidification of whole groups of birds. + +According to Mr. Wallace, even in the groups in which the females, from +being protected in domed nests during incubation, have not had their bright +colours eliminated through natural selection, the males often differ in a +slight, and occasionally in a considerable degree from the females. This +is a significant fact, for such differences in colour must be accounted for +by some of the variations in the males having been from the first limited +in transmission to the same sex; as it can hardly be maintained that these +differences, especially when very slight, serve as a protection to the +female. Thus all the species in the splendid group of the Trogons build in +holes; and Mr. Gould gives figures (21. See his Monograph of the +Trogonidae, 1st edition.) of both sexes of twenty-five species, in all of +which, with one partial exception, the sexes differ sometimes slightly, +sometimes conspicuously, in colour,--the males being always finer than the +females, though the latter are likewise beautiful. All the species of +kingfishers build in holes, and with most of the species the sexes are +equally brilliant, and thus far Mr. Wallace's rule holds good; but in some +of the Australian species the colours of the females are rather less vivid +than those of the male; and in one splendidly-coloured species, the sexes +differ so much that they were at first thought to be specifically distinct. +(22. Namely, Cyanalcyon, Gould's 'Handbook to the Birds of Australia,' +vol. i. p. 133; see, also, pp. 130, 136.) Mr. R.B. Sharpe, who has +especially studied this group, has shewn me some American species (Ceryle) +in which the breast of the male is belted with black. Again, in +Carcineutes, the difference between the sexes is conspicuous: in the male +the upper surface is dull-blue banded with black, the lower surface being +partly fawn-coloured, and there is much red about the head; in the female +the upper surface is reddish-brown banded with black, and the lower surface +white with black markings. It is an interesting fact, as shewing how the +same peculiar style of sexual colouring often characterises allied forms, +that in three species of Dacelo the male differs from the female only in +the tail being dull-blue banded with black, whilst that of the female is +brown with blackish bars; so that here the tail differs in colour in the +two sexes in exactly the same manner as the whole upper surface in the two +sexes of Carcineutes. + +With parrots, which likewise build in holes, we find analogous cases: in +most of the species, both sexes are brilliantly coloured and +indistinguishable, but in not a few species the males are coloured rather +more vividly than the females, or even very differently from them. Thus, +besides other strongly-marked differences, the whole under surface of the +male King Lory (Aprosmictus scapulatus) is scarlet, whilst the throat and +chest of the female is green tinged with red: in the Euphema splendida +there is a similar difference, the face and wing coverts moreover of the +female being of a paler blue than in the male. (23. Every gradation of +difference between the sexes may be followed in the parrots of Australia. +See Gould's 'Handbook,' etc., vol. ii. pp. 14-102.) In the family of the +tits (Parinae), which build concealed nests, the female of our common blue +tomtit (Parus caeruleus), is "much less brightly coloured" than the male: +and in the magnificent Sultan yellow tit of India the difference is +greater. (24. Macgillivray's 'British Birds,' vol. ii. p. 433. Jerdon, +'Birds of India,' vol. ii. p. 282.) + +Again, in the great group of the woodpeckers (25. All the following facts +are taken from M. Malherbe's magnificent 'Monographie des Picidees,' +1861.), the sexes are generally nearly alike, but in the Megapicus validus +all those parts of the head, neck, and breast, which are crimson in the +male are pale brown in the female. As in several woodpeckers the head of +the male is bright crimson, whilst that of the female is plain, it occurred +to me that this colour might possibly make the female dangerously +conspicuous, whenever she put her head out of the hole containing her nest, +and consequently that this colour, in accordance with Mr. Wallace's belief, +had been eliminated. This view is strengthened by what Malherbe states +with respect to Indopicus carlotta; namely, that the young females, like +the young males, have some crimson about their heads, but that this colour +disappears in the adult female, whilst it is intensified in the adult male. +Nevertheless the following considerations render this view extremely +doubtful: the male takes a fair share in incubation (26. Audubon's +'Ornithological Biography,' vol. ii. p. 75; see also the 'Ibis,' vol. i. p. +268.), and would be thus almost equally exposed to danger; both sexes of +many species have their heads of an equally bright crimson; in other +species the difference between the sexes in the amount of scarlet is so +slight that it can hardly make any appreciable difference in the danger +incurred; and lastly, the colouring of the head in the two sexes often +differs slightly in other ways. + +The cases, as yet given, of slight and graduated differences in colour +between the males and females in the groups, in which as a general rule the +sexes resemble each other, all relate to species which build domed or +concealed nests. But similar gradations may likewise be observed in groups +in which the sexes as a general rule resemble each other, but which build +open nests. + +As I have before instanced the Australian parrots, so I may here instance, +without giving any details, the Australian pigeons. (27. Gould's +'Handbook to the Birds of Australia,' vol. ii. pp. 109-149.) It deserves +especial notice that in all these cases the slight differences in plumage +between the sexes are of the same general nature as the occasionally +greater differences. A good illustration of this fact has already been +afforded by those kingfishers in which either the tail alone or the whole +upper surface of the plumage differs in the same manner in the two sexes. +Similar cases may be observed with parrots and pigeons. The differences in +colour between the sexes of the same species are, also, of the same general +nature as the differences in colour between the distinct species of the +same group. For when in a group in which the sexes are usually alike, the +male differs considerably from the female, he is not coloured in a quite +new style. Hence we may infer that within the same group the special +colours of both sexes when they are alike, and the colours of the male, +when he differs slightly or even considerably from the female, have been in +most cases determined by the same general cause; this being sexual +selection. + +It is not probable, as has already been remarked, that differences in +colour between the sexes, when very slight, can be of service to the female +as a protection. Assuming, however, that they are of service, they might +be thought to be cases of transition; but we have no reason to believe that +many species at any one time are undergoing change. Therefore we can +hardly admit that the numerous females which differ very slightly in colour +from their males are now all commencing to become obscure for the sake of +protection. Even if we consider somewhat more marked sexual differences, +is it probable, for instance, that the head of the female chaffinch,--the +crimson on the breast of the female bullfinch,--the green of the female +greenfinch,--the crest of the female golden-crested wren, have all been +rendered less bright by the slow process of selection for the sake of +protection? I cannot think so; and still less with the slight differences +between the sexes of those birds which build concealed nests. On the other +hand, the differences in colour between the sexes, whether great or small, +may to a large extent be explained on the principle of the successive +variations, acquired by the males through sexual selection, having been +from the first more or less limited in their transmission to the females. +That the degree of limitation should differ in different species of the +same group will not surprise any one who has studied the laws of +inheritance, for they are so complex that they appear to us in our +ignorance to be capricious in their action. (28. See remarks to this +effect in 'Variation of Animals and Plants under Domestication,' vol. ii. +chap. xii.) + +As far as I can discover there are few large groups of birds in which all +the species have both sexes alike and brilliantly coloured, but I hear from +Mr. Sclater, that this appears to be the case with the Musophagae or +plantain-eaters. Nor do I believe that any large group exists in which the +sexes of all the species are widely dissimilar in colour: Mr. Wallace +informs me that the chatterers of S. America (Cotingidae) offer one of the +best instances; but with some of the species, in which the male has a +splendid red breast, the female exhibits some red on her breast; and the +females of other species shew traces of the green and other colours of the +males. Nevertheless we have a near approach to close sexual similarity or +dissimilarity throughout several groups: and this, from what has just been +said of the fluctuating nature of inheritance, is a somewhat surprising +circumstance. But that the same laws should largely prevail with allied +animals is not surprising. The domestic fowl has produced a great number +of breeds and sub-breeds, and in these the sexes generally differ in +plumage; so that it has been noticed as an unusual circumstance when in +certain sub-breeds they resemble each other. On the other hand, the +domestic pigeon has likewise produced a vast number of distinct breeds and +sub-breeds, and in these, with rare exceptions, the two sexes are +identically alike. + +Therefore if other species of Gallus and Columba were domesticated and +varied, it would not be rash to predict that similar rules of sexual +similarity and dissimilarity, depending on the form of transmission, would +hold good in both cases. In like manner the same form of transmission has +generally prevailed under nature throughout the same groups, although +marked exceptions to this rule occur. Thus within the same family or even +genus, the sexes may be identically alike, or very different in colour. +Instances have already been given in the same genus, as with sparrows, fly- +catchers, thrushes and grouse. In the family of pheasants the sexes of +almost all the species are wonderfully dissimilar, but are quite alike in +the eared pheasant or Crossoptilon auritum. In two species of Chloephaga, +a genus of geese, the male cannot be distinguished from the females, except +by size; whilst in two others, the sexes are so unlike that they might +easily be mistaken for distinct species. (29. The 'Ibis,' vol. vi. 1864, +p. 122.) + +The laws of inheritance can alone account for the following cases, in which +the female acquires, late in life, certain characters proper to the male, +and ultimately comes to resemble him more or less completely. Here +protection can hardly have come into play. Mr. Blyth informs me that the +females of Oriolus melanocephalus and of some allied species, when +sufficiently mature to breed, differ considerably in plumage from the adult +males; but after the second or third moults they differ only in their beaks +having a slight greenish tinge. In the dwarf bitterns (Ardetta), according +to the same authority, "the male acquires his final livery at the first +moult, the female not before the third or fourth moult; in the meanwhile +she presents an intermediate garb, which is ultimately exchanged for the +same livery as that of the male." So again the female Falco peregrinus +acquires her blue plumage more slowly than the male. Mr. Swinhoe states +that with one of the Drongo shrikes (Dicrurus macrocercus) the male, whilst +almost a nestling, moults his soft brown plumage and becomes of a uniform +glossy greenish-black; but the female retains for a long time the white +striae and spots on the axillary feathers; and does not completely assume +the uniform black colour of the male for three years. The same excellent +observer remarks that in the spring of the second year the female spoon- +bill (Platalea) of China resembles the male of the first year, and that +apparently it is not until the third spring that she acquires the same +adult plumage as that possessed by the male at a much earlier age. The +female Bombycilla carolinensis differs very little from the male, but the +appendages, which like beads of red sealing-wax ornament the wing-feathers +(30. When the male courts the female, these ornaments are vibrated, and +"are shewn off to great advantage," on the outstretched wings: A. Leith +Adams, 'Field and Forest Rambles,' 1873, p. 153.), are not developed in her +so early in life as in the male. In the male of an Indian parrakeet +(Palaeornis javanicus) the upper mandible is coral-red from his earliest +youth, but in the female, as Mr. Blyth has observed with caged and wild +birds, it is at first black and does not become red until the bird is at +least a year old, at which age the sexes resemble each other in all +respects. Both sexes of the wild turkey are ultimately furnished with a +tuft of bristles on the breast, but in two-year-old birds the tuft is about +four inches long in the male and hardly apparent in the female; when, +however, the latter has reached her fourth year, it is from four to five +inches in length. (31. On Ardetta, Translation of Cuvier's 'Regne +Animal,' by Mr. Blyth, footnote, p. 159. On the Peregrine Falcon, Mr. +Blyth, in Charlesworth's 'Mag. of Nat. Hist.' vol. i. 1837, p. 304. On +Dicrurus, 'Ibis,' 1863, p. 44. On the Platalea, 'Ibis,' vol. vi. 1864, p. +366. On the Bombycilla, Audubon's 'Ornitholog. Biography,' vol. i. p. +229. On the Palaeornis, see, also, Jerdon, 'Birds of India,' vol. i. p. +263. On the wild turkey, Audubon, ibid. vol. i. p. 15; but I hear from +Judge Caton that in Illinois the female very rarely acquires a tuft. +Analogous cases with the females of Petrocossyphus are given by Mr. R. +Sharpe, 'Proceedings of the Zoological Society,' 1872, p. 496.) + +These cases must not be confounded with those where diseased or old females +abnormally assume masculine characters, nor with those where fertile +females, whilst young, acquire the characters of the male, through +variation or some unknown cause. (32. Of these latter cases Mr. Blyth has +recorded (Translation of Cuvier's 'Regne Animal,' p. 158) various instances +with Lanius, Ruticilla, Linaria, and Anas. Audubon has also recorded a +similar case ('Ornitholog. Biography,' vol. v. p. 519) with Pyranga +aestiva.) But all these cases have so much in common that they depend, +according to the hypothesis of pangenesis, on gemmules derived from each +part of the male being present, though latent, in the female; their +development following on some slight change in the elective affinities of +her constituent tissues. + +A few words must be added on changes of plumage in relation to the season +of the year. From reasons formerly assigned there can be little doubt that +the elegant plumes, long pendant feathers, crests, etc., of egrets, herons, +and many other birds, which are developed and retained only during the +summer, serve for ornamental and nuptial purposes, though common to both +sexes. The female is thus rendered more conspicuous during the period of +incubation than during the winter; but such birds as herons and egrets +would be able to defend themselves. As, however, plumes would probably be +inconvenient and certainly of no use during the winter, it is possible that +the habit of moulting twice in the year may have been gradually acquired +through natural selection for the sake of casting off inconvenient +ornaments during the winter. But this view cannot be extended to the many +waders, whose summer and winter plumages differ very little in colour. +With defenceless species, in which both sexes, or the males alone, become +extremely conspicuous during the breeding-season,--or when the males +acquire at this season such long wing or tail-feathers as to impede their +flight, as with Cosmetornis and Vidua,--it certainly at first appears +highly probable that the second moult has been gained for the special +purpose of throwing off these ornaments. We must, however, remember that +many birds, such as some of the Birds of Paradise, the Argus pheasant and +peacock, do not cast their plumes during the winter; and it can hardly be +maintained that the constitution of these birds, at least of the +Gallinaceae, renders a double moult impossible, for the ptarmigan moults +thrice in the year. (33. See Gould's 'Birds of Great Britain.') Hence it +must be considered as doubtful whether the many species which moult their +ornamental plumes or lose their bright colours during the winter, have +acquired this habit on account of the inconvenience or danger which they +would otherwise have suffered. + +I conclude, therefore, that the habit of moulting twice in the year was in +most or all cases first acquired for some distinct purpose, perhaps for +gaining a warmer winter covering; and that variations in the plumage +occurring during the summer were accumulated through sexual selection, and +transmitted to the offspring at the same season of the year; that such +variations were inherited either by both sexes or by the males alone, +according to the form of inheritance which prevailed. This appears more +probable than that the species in all cases originally tended to retain +their ornamental plumage during the winter, but were saved from this +through natural selection, resulting from the inconvenience or danger thus +caused. + +I have endeavoured in this chapter to shew that the arguments are not +trustworthy in favour of the view that weapons, bright colours, and various +ornaments, are now confined to the males owing to the conversion, by +natural selection, of the equal transmission of characters to both sexes, +into transmission to the male sex alone. It is also doubtful whether the +colours of many female birds are due to the preservation, for the sake of +protection, of variations which were from the first limited in their +transmission to the female sex. But it will be convenient to defer any +further discussion on this subject until I treat, in the following chapter, +of the differences in plumage between the young and old. + + +CHAPTER XVI. + +BIRDS--concluded. + +The immature plumage in relation to the character of the plumage in both +sexes when adult--Six classes of cases--Sexual differences between the +males of closely-allied or representative species--The female assuming the +characters of the male--Plumage of the young in relation to the summer and +winter plumage of the adults--On the increase of beauty in the birds of the +world--Protective colouring--Conspicuously coloured birds--Novelty +appreciated--Summary of the four chapters on Birds. + +We must now consider the transmission of characters, as limited by age, in +reference to sexual selection. The truth and importance of the principle +of inheritance at corresponding ages need not here be discussed, as enough +has already been said on the subject. Before giving the several rather +complex rules or classes of cases, under which the differences in plumage +between the young and the old, as far as known to me, may be included, it +will be well to make a few preliminary remarks. + +With animals of all kinds when the adults differ in colour from the young, +and the colours of the latter are not, as far as we can see, of any special +service, they may generally be attributed, like various embryological +structures, to the retention of a former character. But this view can be +maintained with confidence, only when the young of several species resemble +each other closely, and likewise resemble other adult species belonging to +the same group; for the latter are the living proofs that such a state of +things was formerly possible. Young lions and pumas are marked with feeble +stripes or rows of spots, and as many allied species both young and old are +similarly marked, no believer in evolution will doubt that the progenitor +of the lion and puma was a striped animal, and that the young have retained +vestiges of the stripes, like the kittens of black cats, which are not in +the least striped when grown up. Many species of deer, which when mature +are not spotted, are whilst young covered with white spots, as are likewise +some few species in the adult state. So again the young in the whole +family of pigs (Suidae), and in certain rather distantly allied animals, +such as the tapir, are marked with dark longitudinal stripes; but here we +have a character apparently derived from an extinct progenitor, and now +preserved by the young alone. In all such cases the old have had their +colours changed in the course of time, whilst the young have remained but +little altered, and this has been effected through the principle of +inheritance at corresponding ages. + +This same principle applies to many birds belonging to various groups, in +which the young closely resemble each other, and differ much from their +respective adult parents. The young of almost all the Gallinaceae, and of +some distantly allied birds such as ostriches, are covered with +longitudinally striped down; but this character points back to a state of +things so remote that it hardly concerns us. Young cross-bills (Loxia) +have at first straight beaks like those of other finches, and in their +immature striated plumage they resemble the mature red-pole and female +siskin, as well as the young of the goldfinch, greenfinch, and some other +allied species. The young of many kinds of buntings (Emberiza) resemble +one another, and likewise the adult state of the common bunting, E. +miliaria. In almost the whole large group of thrushes the young have their +breasts spotted--a character which is retained throughout life by many +species, but is quite lost by others, as by the Turdus migratorius. So +again with many thrushes, the feathers on the back are mottled before they +are moulted for the first time, and this character is retained for life by +certain eastern species. The young of many species of shrikes (Lanius), of +some woodpeckers, and of an Indian pigeon (Chalcophaps indicus), are +transversely striped on the under surface; and certain allied species or +whole genera are similarly marked when adult. In some closely-allied and +resplendent Indian cuckoos (Chrysococcyx), the mature species differ +considerably from one another in colour, but the young cannot be +distinguished. The young of an Indian goose (Sarkidiornis melanonotus) +closely resemble in plumage an allied genus, Dendrocygna, when mature. (1. +In regard to thrushes, shrikes, and woodpeckers, see Mr. Blyth, in +Charlesworth's 'Mag. of Nat. Hist.' vol. i. 1837, p. 304; also footnote to +his translation of Cuvier's 'Regne Animal,' p. 159. I give the case of +Loxia on Mr. Blyth's information. On thrushes, see also Audubon, 'Ornith. +Biog.' vol. ii. p. 195. On Chrysococcyx and Chalcophaps, Blyth, as quoted +in Jerdon's 'Birds of India,' vol. iii. p. 485. On Sarkidiornis, Blyth, in +'Ibis,' 1867, p. 175.) Similar facts will hereafter be given in regard to +certain herons. Young black-grouse (Tetrao tetrix) resemble the young as +well as the old of certain other species, for instance the red-grouse or T. +scoticus. Finally, as Mr. Blyth, who has attended closely to this subject, +has well remarked, the natural affinities of many species are best +exhibited in their immature plumage; and as the true affinities of all +organic beings depend on their descent from a common progenitor, this +remark strongly confirms the belief that the immature plumage approximately +shews us the former or ancestral condition of the species. + +Although many young birds, belonging to various families, thus give us a +glimpse of the plumage of their remote progenitors, yet there are many +other birds, both dull-coloured and bright-coloured, in which the young +closely resemble their parents. In such cases the young of the different +species cannot resemble each other more closely than do the parents; nor +can they strikingly resemble allied forms when adult. They give us but +little insight into the plumage of their progenitors, excepting in so far +that, when the young and the old are coloured in the same general manner +throughout a whole group of species, it is probable that their progenitors +were similarly coloured. + +We may now consider the classes of cases, under which the differences and +resemblances between the plumage of the young and the old, in both sexes or +in one sex alone, may be grouped. Rules of this kind were first enounced +by Cuvier; but with the progress of knowledge they require some +modification and amplification. This I have attempted to do, as far as the +extreme complexity of the subject permits, from information derived from +various sources; but a full essay on this subject by some competent +ornithologist is much needed. In order to ascertain to what extent each +rule prevails, I have tabulated the facts given in four great works, +namely, by Macgillivray on the birds of Britain, Audubon on those of North +America, Jerdon on those of India, and Gould on those of Australia. I may +here premise, first, that the several cases or rules graduate into each +other; and secondly, that when the young are said to resemble their +parents, it is not meant that they are identically alike, for their colours +are almost always less vivid, and the feathers are softer and often of a +different shape. + +RULES OR CLASSES OF CASES. + +I. When the adult male is more beautiful or conspicuous than the adult +female, the young of both sexes in their first plumage closely resemble the +adult female, as with the common fowl and peacock; or, as occasionally +occurs, they resemble her much more closely than they do the adult male. + +II. When the adult female is more conspicuous than the adult male, as +sometimes though rarely occurs, the young of both sexes in their first +plumage resemble the adult male. + +III. When the adult male resembles the adult female, the young of both +sexes have a peculiar first plumage of their own, as with the robin. + +IV. When the adult male resembles the adult female, the young of both +sexes in their first plumage resemble the adults, as with the kingfisher, +many parrots, crows, hedge-warblers. + +V. When the adults of both sexes have a distinct winter and summer +plumage, whether or not the male differs from the female, the young +resemble the adults of both sexes in their winter dress, or much more +rarely in their summer dress, or they resemble the females alone. Or the +young may have an intermediate character; or again they may differ greatly +from the adults in both their seasonal plumages. + +VI. In some few cases the young in their first plumage differ from each +other according to sex; the young males resembling more or less closely the +adult males, and the young females more or less closely the adult females. + +CLASS I. + +In this class, the young of both sexes more or less closely resemble the +adult female, whilst the adult male differs from the adult female, often in +the most conspicuous manner. Innumerable instances in all Orders could be +given; it will suffice to call to mind the common pheasant, duck, and +house-sparrow. The cases under this class graduate into others. Thus the +two sexes when adult may differ so slightly, and the young so slightly from +the adults, that it is doubtful whether such cases ought to come under the +present, or under the third or fourth classes. So again the young of the +two sexes, instead of being quite alike, may differ in a slight degree from +each other, as in our sixth class. These transitional cases, however, are +few, or at least are not strongly pronounced, in comparison with those +which come strictly under the present class. + +The force of the present law is well shewn in those groups, in which, as a +general rule, the two sexes and the young are all alike; for when in these +groups the male does differ from the female, as with certain parrots, +kingfishers, pigeons, etc., the young of both sexes resemble the adult +female. (2. See, for instance, Mr. Gould's account ('Handbook to the +Birds of Australia,' vol. i. p. 133) of Cyanalcyon (one of the +Kingfishers), in which, however, the young male, though resembling the +adult female, is less brilliantly coloured. In some species of Dacelo the +males have blue tails, and the females brown ones; and Mr. R.B. Sharpe +informs me that the tail of the young male of D. gaudichaudi is at first +brown. Mr. Gould has described (ibid. vol. ii. pp. 14, 20, 37) the sexes +and the young of certain black Cockatoos and of the King Lory, with which +the same rule prevails. Also Jerdon ('Birds of India,' vol. i. p. 260) on +the Palaeornis rosa, in which the young are more like the female than the +male. See Audubon ('Ornithological Biography,' vol. ii. p. 475) on the two +sexes and the young of Columba passerina.) We see the same fact exhibited +still more clearly in certain anomalous cases; thus the male of Heliothrix +auriculata (one of the humming-birds) differs conspicuously from the female +in having a splendid gorget and fine ear-tufts, but the female is +remarkable from having a much longer tail than that of the male; now the +young of both sexes resemble (with the exception of the breast being +spotted with bronze) the adult female in all other respects, including the +length of her tail, so that the tail of the male actually becomes shorter +as he reaches maturity, which is a most unusual circumstance. (3. I owe +this information to Mr. Gould, who shewed me the specimens; see also his +'Introduction to the Trochilidae,' 1861, p. 120.) Again, the plumage of +the male goosander (Mergus merganser) is more conspicuously coloured than +that of the female, with the scapular and secondary wing-feathers much +longer; but differently from what occurs, as far as I know, in any other +bird, the crest of the adult male, though broader than that of the female, +is considerably shorter, being only a little above an inch in length; the +crest of the female being two and a half inches long. Now the young of +both sexes entirely resemble the adult female, so that their crests are +actually of greater length, though narrower, than in the adult male. (4. +Macgillivray, 'Hist. Brit. Birds,' vol. v. pp. 207-214.) + +When the young and the females closely resemble each other and both differ +from the males, the most obvious conclusion is that the males alone have +been modified. Even in the anomalous cases of the Heliothrix and Mergus, +it is probable that originally both adult sexes were furnished--the one +species with a much elongated tail, and the other with a much elongated +crest--these characters having since been partially lost by the adult males +from some unexplained cause, and transmitted in their diminished state to +their male offspring alone, when arrived at the corresponding age of +maturity. The belief that in the present class the male alone has been +modified, as far as the differences between the male and the female +together with her young are concerned, is strongly supported by some +remarkable facts recorded by Mr. Blyth (5. See his admirable paper in the +'Journal of the Asiatic Soc. of Bengal,' vol. xix. 1850, p. 223; see also +Jerdon, 'Birds of India,' vol. i. introduction, p. xxix. In regard to +Tanysiptera, Prof. Schlegel told Mr. Blyth that he could distinguish +several distinct races, solely by comparing the adult males.), with respect +to closely-allied species which represent each other in distinct countries. +For with several of these representative species the adult males have +undergone a certain amount of change and can be distinguished; the females +and the young from the distinct countries being indistinguishable, and +therefore absolutely unchanged. This is the case with certain Indian chats +(Thamnobia), with certain honey-suckers (Nectarinia), shrikes +(Tephrodornis), certain kingfishers (Tanysiptera), Kalij pheasants +(Gallophasis), and tree-partridges (Arboricola). + +In some analogous cases, namely with birds having a different summer and +winter plumage, but with the two sexes nearly alike, certain closely-allied +species can easily be distinguished in their summer or nuptial plumage, yet +are indistinguishable in their winter as well as in their immature plumage. +This is the case with some of the closely-allied Indian wagtails or +Motacillae. Mr. Swinhoe (6. See also Mr. Swinhoe, in 'Ibis,' July 1863, +p. 131; and a previous paper, with an extract from a note by Mr. Blyth, in +'Ibis,' January, 1861, p. 25.) informs me that three species of Ardeola, a +genus of herons, which represent one another on separate continents, are +"most strikingly different" when ornamented with their summer plumes, but +are hardly, if at all, distinguishable during the winter. The young also +of these three species in their immature plumage closely resemble the +adults in their winter dress. This case is all the more interesting, +because with two other species of Ardeola both sexes retain, during the +winter and summer, nearly the same plumage as that possessed by the three +first species during the winter and in their immature state; and this +plumage, which is common to several distinct species at different ages and +seasons, probably shews us how the progenitors of the genus were coloured. +In all these cases, the nuptial plumage which we may assume was originally +acquired by the adult males during the breeding-season, and transmitted to +the adults of both sexes at the corresponding season, has been modified, +whilst the winter and immature plumages have been left unchanged. + +The question naturally arises, how is it that in these latter cases the +winter plumage of both sexes, and in the former cases the plumage of the +adult females, as well as the immature plumage of the young, have not been +at all affected? The species which represent each other in distinct +countries will almost always have been exposed to somewhat different +conditions, but we can hardly attribute to this action the modification of +the plumage in the males alone, seeing that the females and the young, +though similarly exposed, have not been affected. Hardly any fact shews us +more clearly how subordinate in importance is the direct action of the +conditions of life, in comparison with the accumulation through selection +of indefinite variations, than the surprising difference between the sexes +of many birds; for both will have consumed the same food, and have been +exposed to the same climate. Nevertheless we are not precluded from +believing that in the course of time new conditions may produce some direct +effect either on both sexes, or from their constitutional differences +chiefly on one sex. We see only that this is subordinate in importance to +the accumulated results of selection. Judging, however, from a wide-spread +analogy, when a species migrates into a new country (and this must precede +the formation of representative species), the changed conditions to which +they will almost always have been exposed will cause them to undergo a +certain amount of fluctuating variability. In this case sexual selection, +which depends on an element liable to change--the taste or admiration of +the female--will have had new shades of colour or other differences to act +on and accumulate; and as sexual selection is always at work, it would +(from what we know of the results on domestic animals of man's +unintentional selection), be surprising if animals inhabiting separate +districts, which can never cross and thus blend their newly-acquired +characters, were not, after a sufficient lapse of time, differently +modified. These remarks likewise apply to the nuptial or summer plumage, +whether confined to the males, or common to both sexes. + +Although the females of the above closely-allied or representative species, +together with their young, differ hardly at all from one another, so that +the males alone can be distinguished, yet the females of most species +within the same genus obviously differ from each other. The differences, +however, are rarely as great as between the males. We see this clearly in +the whole family of the Gallinaceae: the females, for instance, of the +common and Japan pheasant, and especially of the gold and Amherst pheasant +--of the silver pheasant and the wild fowl--resemble one another very +closely in colour, whilst the males differ to an extraordinary degree. So +it is with the females of most of the Cotingidae, Fringillidae, and many +other families. There can indeed be no doubt that, as a general rule, the +females have been less modified than the males. Some few birds, however, +offer a singular and inexplicable exception; thus the females of Paradisea +apoda and P. papuana differ from each other more than do their respective +males (7. Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 394.); the +female of the latter species having the under surface pure white, whilst +the female P. apoda is deep brown beneath. So, again, as I hear from +Professor Newton, the males of two species of Oxynotus (shrikes), which +represent each other in the islands of Mauritius and Bourbon (8. These +species are described with coloured figures, by M. F. Pollen, in 'Ibis,' +1866, p. 275.), differ but little in colour, whilst the females differ +much. In the Bourbon species the female appears to have partially retained +an immature condition of plumage, for at first sight she "might be taken +for the young of the Mauritian species." These differences may be compared +with those inexplicable ones, which occur independently of man's selection +in certain sub-breeds of the game-fowl, in which the females are very +different, whilst the males can hardly be distinguished. (9. 'Variation +of Animals,' etc., vol. i. p. 251.) + +As I account so largely by sexual selection for the differences between the +males of allied species, how can the differences between the females be +accounted for in all ordinary cases? We need not here consider the species +which belong to distinct genera; for with these, adaptation to different +habits of life, and other agencies, will have come into play. In regard to +the differences between the females within the same genus, it appears to me +almost certain, after looking through various large groups, that the chief +agent has been the greater or less transference to the female of the +characters acquired by the males through sexual selection. In the several +British finches, the two sexes differ either very slightly or considerably; +and if we compare the females of the greenfinch, chaffinch, goldfinch, +bullfinch, crossbill, sparrow, etc., we shall see that they differ from one +another chiefly in the points in which they partially resemble their +respective males; and the colours of the males may safely be attributed to +sexual selection. With many gallinaceous species the sexes differ to an +extreme degree, as with the peacock, pheasant, and fowl, whilst with other +species there has been a partial or even complete transference of character +from the male to the female. The females of the several species of +Polyplectron exhibit in a dim condition, and chiefly on the tail, the +splendid ocelli of their males. The female partridge differs from the male +only in the red mark on her breast being smaller; and the female wild +turkey only in her colours being much duller. In the guinea-fowl the two +sexes are indistinguishable. There is no improbability in the plain, +though peculiarly spotted plumage of this latter bird having been acquired +through sexual selection by the males, and then transmitted to both sexes; +for it is not essentially different from the much more beautifully spotted +plumage, characteristic of the males alone of the Tragopan pheasants. + +It should be observed that, in some instances, the transference of +characters from the male to the female has been effected apparently at a +remote period, the male having subsequently undergone great changes, +without transferring to the female any of his later-gained characters. For +instance, the female and the young of the black-grouse (Tetrao tetrix) +resemble pretty closely both sexes and the young of the red-grouse (T. +scoticus); and we may consequently infer that the black-grouse is descended +from some ancient species, of which both sexes were coloured in nearly the +same manner as the red-grouse. As both sexes of this latter species are +more distinctly barred during the breeding-season than at any other time, +and as the male differs slightly from the female in his more strongly- +pronounced red and brown tints (10. Macgillivray, 'History of British +Birds,' vol. i. pp. 172-174.), we may conclude that his plumage has been +influenced by sexual selection, at least to a certain extent. If so, we +may further infer that nearly similar plumage of the female black-grouse +was similarly produced at some former period. But since this period the +male black-grouse has acquired his fine black plumage, with his forked and +outwardly-curled tail-feathers; but of these characters there has hardly +been any transference to the female, excepting that she shews in her tail a +trace of the curved fork. + +We may therefore conclude that the females of distinct though allied +species have often had their plumage rendered more or less different by the +transference in various degrees of characters acquired by the males through +sexual selection, both during former and recent times. But it deserves +especial attention that brilliant colours have been transferred much more +rarely than other tints. For instance, the male of the red-throated blue- +breast (Cyanecula suecica) has a rich blue breast, including a sub- +triangular red mark; now marks of nearly the same shape have been +transferred to the female, but the central space is fulvous instead of red, +and is surrounded by mottled instead of blue feathers. The Gallinaceae +offer many analogous cases; for none of the species, such as partridges, +quails, guinea-fowls, etc., in which the colours of the plumage have been +largely transferred from the male to the female, are brilliantly coloured. +This is well exemplified with the pheasants, in which the male is generally +so much more brilliant than the female; but with the Eared and Cheer +pheasants (Crossoptilon auritum and Phasianus wallichii) the sexes closely +resemble each other and their colours are dull. We may go so far as to +believe that if any part of the plumage in the males of these two pheasants +had been brilliantly coloured, it would not have been transferred to the +females. These facts strongly support Mr. Wallace's view that with birds +which are exposed to much danger during incubation, the transference of +bright colours from the male to the female has been checked through natural +selection. We must not, however, forget that another explanation, before +given, is possible; namely, that the males which varied and became bright, +whilst they were young and inexperienced, would have been exposed to much +danger, and would generally have been destroyed; the older and more +cautious males, on the other hand, if they varied in a like manner, would +not only have been able to survive, but would have been favoured in their +rivalry with other males. Now variations occurring late in life tend to be +transmitted exclusively to the same sex, so that in this case extremely +bright tints would not have been transmitted to the females. On the other +hand, ornaments of a less conspicuous kind, such as those possessed by the +Eared and Cheer pheasants, would not have been dangerous, and if they +appeared during early youth, would generally have been transmitted to both +sexes. + +In addition to the effects of the partial transference of characters from +the males to the females, some of the differences between the females of +closely allied species may be attributed to the direct or definite action +of the conditions of life. (11. See, on this subject, chap. xxiii. in the +'Variation of Animals and Plants under Domestication.') With the males, +any such action would generally have been masked by the brilliant colours +gained through sexual selection; but not so with the females. Each of the +endless diversities in plumage which we see in our domesticated birds is, +of course, the result of some definite cause; and under natural and more +uniform conditions, some one tint, assuming that it was in no way +injurious, would almost certainly sooner or later prevail. The free +intercrossing of the many individuals belonging to the same species would +ultimately tend to make any change of colour, thus induced, uniform in +character. + +No one doubts that both sexes of many birds have had their colours adapted +for the sake of protection; and it is possible that the females alone of +some species may have been modified for this end. Although it would be a +difficult, perhaps an impossible process, as shewn in the last chapter, to +convert one form of transmission into another through selection, there +would not be the least difficulty in adapting the colours of the female, +independently of those of the male, to surrounding objects, through the +accumulation of variations which were from the first limited in their +transmission to the female sex. If the variations were not thus limited, +the bright tints of the male would be deteriorated or destroyed. Whether +the females alone of many species have been thus specially modified, is at +present very doubtful. I wish I could follow Mr. Wallace to the full +extent; for the admission would remove some difficulties. Any variations +which were of no service to the female as a protection would be at once +obliterated, instead of being lost simply by not being selected, or from +free intercrossing, or from being eliminated when transferred to the male +and in any way injurious to him. Thus the plumage of the female would be +kept constant in character. It would also be a relief if we could admit +that the obscure tints of both sexes of many birds had been acquired and +preserved for the sake of protection,--for example, of the hedge-warbler or +kitty-wren (Accentor modularis and Troglodytes vulgaris), with respect to +which we have no sufficient evidence of the action of sexual selection. We +ought, however, to be cautious in concluding that colours which appear to +us dull, are not attractive to the females of certain species; we should +bear in mind such cases as that of the common house-sparrow, in which the +male differs much from the female, but does not exhibit any bright tints. +No one probably will dispute that many gallinaceous birds which live on the +open ground, have acquired their present colours, at least in part, for the +sake of protection. We know how well they are thus concealed; we know that +ptarmigans, whilst changing from their winter to their summer plumage, both +of which are protective, suffer greatly from birds of prey. But can we +believe that the very slight differences in tints and markings between, for +instance, the female black-grouse and red-grouse serve as a protection? +Are partridges, as they are now coloured, better protected than if they had +resembled quails? Do the slight differences between the females of the +common pheasant, the Japan and gold pheasants, serve as a protection, or +might not their plumages have been interchanged with impunity? From what +Mr. Wallace has observed of the habits of certain gallinaceous birds in the +East, he thinks that such slight differences are beneficial. For myself, I +will only say that I am not convinced. + +Formerly when I was inclined to lay much stress on protection as accounting +for the duller colours of female birds, it occurred to me that possibly +both sexes and the young might aboriginally have been equally bright +coloured; but that subsequently, the females from the danger incurred +during incubation, and the young from being inexperienced, had been +rendered dull as a protection. But this view is not supported by any +evidence, and is not probable; for we thus in imagination expose during +past times the females and the young to danger, from which it has +subsequently been necessary to shield their modified descendants. We have, +also, to reduce, through a gradual process of selection, the females and +the young to almost exactly the same tints and markings, and to transmit +them to the corresponding sex and period of life. On the supposition that +the females and the young have partaken during each stage of the process of +modification of a tendency to be as brightly coloured as the males, it is +also a somewhat strange fact that the females have never been rendered +dull-coloured without the young participating in the same change; for there +are no instances, as far as I can discover, of species with the females +dull and the young bright coloured. A partial exception, however, is +offered by the young of certain woodpeckers, for they have "the whole upper +part of the head tinged with red," which afterwards either decreases into a +mere circular red line in the adults of both sexes, or quite disappears in +the adult females. (12. Audubon, 'Ornith. Biography,' vol. i. p. 193. +Macgillivray, 'History of British Birds,' vol. iii. p. 85. See also the +case before given of Indopicus carlotta.) + +Finally, with respect to our present class of cases, the most probable view +appears to be that successive variations in brightness or in other +ornamental characters, occurring in the males at a rather late period of +life have alone been preserved; and that most or all of these variations, +owing to the late period of life at which they appeared, have been from the +first transmitted only to the adult male offspring. Any variations in +brightness occurring in the females or in the young, would have been of no +service to them, and would not have been selected; and moreover, if +dangerous, would have been eliminated. Thus the females and the young will +either have been left unmodified, or (as is much more common) will have +been partially modified by receiving through transference from the males +some of his successive variations. Both sexes have perhaps been directly +acted on by the conditions of life to which they have long been exposed: +but the females from not being otherwise much modified, will best exhibit +any such effects. These changes and all others will have been kept uniform +by the free intercrossing of many individuals. In some cases, especially +with ground birds, the females and the young may possibly have been +modified, independently of the males, for the sake of protection, so as to +have acquired the same dull-coloured plumage. + +CLASS II. + +WHEN THE ADULT FEMALE IS MORE CONSPICUOUS THAN THE ADULT MALE, THE YOUNG OF +BOTH SEXES IN THEIR FIRST PLUMAGE RESEMBLE THE ADULT MALE. + +This class is exactly the reverse of the last, for the females are here +brighter coloured or more conspicuous than the males; and the young, as far +as they are known, resemble the adult males instead of the adult females. +But the difference between the sexes is never nearly so great as with many +birds in the first class, and the cases are comparatively rare. Mr. +Wallace, who first called attention to the singular relation which exists +between the less bright colours of the males and their performing the +duties of incubation, lays great stress on this point (13. 'Westminster +Review,' July 1867, and A. Murray, 'Journal of Travel,' 1868, p. 83.), as a +crucial test that obscure colours have been acquired for the sake of +protection during the period of nesting. A different view seems to me more +probable. As the cases are curious and not numerous, I will briefly give +all that I have been able to find. + +In one section of the genus Turnix, quail-like birds, the female is +invariably larger than the male (being nearly twice as large in one of the +Australian species), and this is an unusual circumstance with the +Gallinaceae. In most of the species the female is more distinctly coloured +and brighter than the male (14. For the Australian species, see Gould's +'Handbook,' etc., vol. ii. pp. 178, 180, 186, and 188. In the British +Museum specimens of the Australian Plain-wanderer (Pedionomus torquatus) +may be seen, shewing similar sexual differences.), but in some few species +the sexes are alike. In Turnix taigoor of India the male "wants the black +on the throat and neck, and the whole tone of the plumage is lighter and +less pronounced than that of the female." The female appears to be +noisier, and is certainly much more pugnacious than the male; so that the +females and not the males are often kept by the natives for fighting, like +game-cocks. As male birds are exposed by the English bird-catchers for a +decoy near a trap, in order to catch other males by exciting their rivalry, +so the females of this Turnix are employed in India. When thus exposed the +females soon begin their "loud purring call, which can be heard a long way +off, and any females within ear-shot run rapidly to the spot, and commence +fighting with the caged bird." In this way from twelve to twenty birds, +all breeding females, may be caught in the course of a single day. The +natives assert that the females after laying their eggs associate in +flocks, and leave the males to sit on them. There is no reason to doubt +the truth of this assertion, which is supported by some observations made +in China by Mr. Swinhoe. (15. Jerdon, 'Birds of India,' vol. iii. p. 596. +Mr. Swinhoe, in 'Ibis,' 1865, p. 542; 1866, pp. 131, 405.) Mr. Blyth +believes, that the young of both sexes resemble the adult male. + +[Fig. 62. Rhynchaea capensis (from Brehm).] + +The females of the three species of Painted Snipes (Rhynchaea, Fig. 62) +"are not only larger but much more richly coloured than the males." (16. +Jerdon, 'Birds of India,' vol. iii. p. 677.) With all other birds in which +the trachea differs in structure in the two sexes it is more developed and +complex in the male than in the female; but in the Rhynchaea australis it +is simple in the male, whilst in the female it makes four distinct +convolutions before entering the lungs. (17. Gould's 'Handbook to the +Birds of Australia,' vol. ii. p. 275.) The female therefore of this +species has acquired an eminently masculine character. Mr. Blyth +ascertained, by examining many specimens, that the trachea is not +convoluted in either sex of R. bengalensis, which species resembles R. +australis so closely, that it can hardly be distinguished except by its +shorter toes. This fact is another striking instance of the law that +secondary sexual characters are often widely different in closely-allied +forms, though it is a very rare circumstance when such differences relate +to the female sex. The young of both sexes of R. bengalensis in their +first plumage are said to resemble the mature male. (18. 'The Indian +Field,' Sept. 1858, p. 3.) There is also reason to believe that the male +undertakes the duty of incubation, for Mr. Swinhoe (19. 'Ibis,' 1866, p. +298.) found the females before the close of the summer associated in +flocks, as occurs with the females of the Turnix. + +The females of Phalaropus fulicarius and P. hyperboreus are larger, and in +their summer plumage "more gaily attired than the males." But the +difference in colour between the sexes is far from conspicuous. According +to Professor Steenstrup, the male alone of P. fulicarius undertakes the +duty of incubation; this is likewise shewn by the state of his breast- +feathers during the breeding-season. The female of the dotterel plover +(Eudromias morinellus) is larger than the male, and has the red and black +tints on the lower surface, the white crescent on the breast, and the +stripes over the eyes, more strongly pronounced. The male also takes at +least a share in hatching the eggs; but the female likewise attends to the +young. (20. For these several statements, see Mr. Gould's 'Birds of Great +Britain.' Prof. Newton informs me that he has long been convinced, from +his own observations and from those of others, that the males of the above- +named species take either the whole or a large share of the duties of +incubation, and that they "shew much greater devotion towards their young, +when in danger, than do the females." So it is, as he informs me, with +Limosa lapponica and some few other Waders, in which the females are larger +and have more strongly contrasted colours than the males.) I have not been +able to discover whether with these species the young resemble the adult +males more closely than the adult females; for the comparison is somewhat +difficult to make on account of the double moult. + +Turning now to the ostrich Order: the male of the common cassowary +(Casuarius galeatus) would be thought by any one to be the female, from his +smaller size and from the appendages and naked skin about his head being +much less brightly coloured; and I am informed by Mr. Bartlett that in the +Zoological Gardens, it is certainly the male alone who sits on the eggs and +takes care of the young. (21. The natives of Ceram (Wallace, 'Malay +Archipelago,' vol. ii. p. 150) assert that the male and female sit +alternately on the eggs; but this assertion, as Mr. Bartlett thinks, may be +accounted for by the female visiting the nest to lay her eggs.) The female +is said by Mr. T.W. Wood (22. The 'Student,' April 1870, p. 124.) to +exhibit during the breeding-season a most pugnacious disposition; and her +wattles then become enlarged and more brilliantly coloured. So again the +female of one of the emus (Dromoeus irroratus) is considerably larger than +the male, and she possesses a slight top-knot, but is otherwise +indistinguishable in plumage. She appears, however, "to have greater +power, when angry or otherwise excited, of erecting, like a turkey-cock, +the feathers of her neck and breast. She is usually the more courageous +and pugilistic. She makes a deep hollow guttural boom especially at night, +sounding like a small gong. The male has a slenderer frame and is more +docile, with no voice beyond a suppressed hiss when angry, or a croak." He +not only performs the whole duty of incubation, but has to defend the young +from their mother; "for as soon as she catches sight of her progeny she +becomes violently agitated, and notwithstanding the resistance of the +father appears to use her utmost endeavours to destroy them. For months +afterwards it is unsafe to put the parents together, violent quarrels being +the inevitable result, in which the female generally comes off conqueror." +(23. See the excellent account of the habits of this bird under +confinement, by Mr. A.W. Bennett, in 'Land and Water,' May 1868, p. 233.) +So that with this emu we have a complete reversal not only of the parental +and incubating instincts, but of the usual moral qualities of the two +sexes; the females being savage, quarrelsome, and noisy, the males gentle +and good. The case is very different with the African ostrich, for the +male is somewhat larger than the female and has finer plumes with more +strongly contrasted colours; nevertheless he undertakes the whole duty of +incubation. (24. Mr. Sclater, on the incubation of the Struthiones, +'Proc. Zool. Soc.' June 9, 1863. So it is with the Rhea darwinii: Captain +Musters says ('At Home with the Patagonians,' 1871, p. 128), that the male +is larger, stronger and swifter than the female, and of slightly darker +colours; yet he takes sole charge of the eggs and of the young, just as +does the male of the common species of Rhea.) + +I will specify the few other cases known to me, in which the female is more +conspicuously coloured than the male, although nothing is known about the +manner of incubation. With the carrion-hawk of the Falkland Islands +(Milvago leucurus) I was much surprised to find by dissection that the +individuals, which had all their tints strongly pronounced, with the cere +and legs orange-coloured, were the adult females; whilst those with duller +plumage and grey legs were the males or the young. In an Australian tree- +creeper (Climacteris erythrops) the female differs from the male in "being +adorned with beautiful, radiated, rufous markings on the throat, the male +having this part quite plain." Lastly, in an Australian night-jar "the +female always exceeds the male in size and in the brilliance of her tints; +the males, on the other hand, have two white spots on the primaries more +conspicuous than in the female." (25. For the Milvago, see 'Zoology of +the Voyage of the "Beagle," Birds,' 1841, p. 16. For the Climacteris and +night-jar (Eurostopodus), see Gould's 'Handbook to the Birds of Australia,' +vol. i. pp. 602 and 97. The New Zealand shieldrake (Tadorna variegata) +offers a quite anomalous case; the head of the female is pure white, and +her back is redder than that of the male; the head of the male is of a rich +dark bronzed colour, and his back is clothed with finely pencilled slate- +coloured feathers, so that altogether he may be considered as the more +beautiful of the two. He is larger and more pugnacious than the female, +and does not sit on the eggs. So that in all these respects this species +comes under our first class of cases; but Mr. Sclater ('Proceedings of the +Zoological Society,' 1866, p. 150) was much surprised to observe that the +young of both sexes, when about three months old, resembled in their dark +heads and necks the adult males, instead of the adult females; so that it +would appear in this case that the females have been modified, whilst the +males and the young have retained a former state of plumage.) + +We thus see that the cases in which female birds are more conspicuously +coloured than the males, with the young in their immature plumage +resembling the adult males instead of the adult females, as in the previous +class, are not numerous, though they are distributed in various Orders. +The amount of difference, also, between the sexes is incomparably less than +that which frequently occurs in the last class; so that the cause of the +difference, whatever it may have been, has here acted on the females either +less energetically or less persistently than on the males in the last +class. Mr. Wallace believes that the males have had their colours rendered +less conspicuous for the sake of protection during the period of +incubation; but the difference between the sexes in hardly any of the +foregoing cases appears sufficiently great for this view to be safely +accepted. In some of the cases, the brighter tints of the female are +almost confined to the lower surface, and the males, if thus coloured, +would not have been exposed to danger whilst sitting on the eggs. It +should also be borne in mind that the males are not only in a slight degree +less conspicuously coloured than the females, but are smaller and weaker. +They have, moreover, not only acquired the maternal instinct of incubation, +but are less pugnacious and vociferous than the females, and in one +instance have simpler vocal organs. Thus an almost complete transposition +of the instincts, habits, disposition, colour, size, and of some points of +structure, has been effected between the two sexes. + +Now if we might assume that the males in the present class have lost some +of that ardour which is usual to their sex, so that they no longer search +eagerly for the females; or, if we might assume that the females have +become much more numerous than the males--and in the case of one Indian +Turnix the females are said to be "much more commonly met with than the +males" (26. Jerdon, 'Birds of India,' vol. iii. p. 598.)--then it is not +improbable that the females would have been led to court the males, instead +of being courted by them. This indeed is the case to a certain extent with +some birds, as we have seen with the peahen, wild turkey, and certain kinds +of grouse. Taking as our guide the habits of most male birds, the greater +size and strength as well as the extraordinary pugnacity of the females of +the Turnix and emu, must mean that they endeavour to drive away rival +females, in order to gain possession of the male; and on this view all the +facts become clear; for the males would probably be most charmed or excited +by the females which were the most attractive to them by their bright +colours, other ornaments, or vocal powers. Sexual selection would then do +its work, steadily adding to the attractions of the females; the males and +the young being left not at all, or but little modified. + +CLASS III. + +WHEN THE ADULT MALE RESEMBLES THE ADULT FEMALE, THE YOUNG OF BOTH SEXES +HAVE A PECULIAR FIRST PLUMAGE OF THEIR OWN. + +In this class the sexes when adult resemble each other, and differ from the +young. This occurs with many birds of many kinds. The male robin can +hardly be distinguished from the female, but the young are widely +different, with their mottled dusky-olive and brown plumage. The male and +female of the splendid scarlet ibis are alike, whilst the young are brown; +and the scarlet colour, though common to both sexes, is apparently a sexual +character, for it is not well developed in either sex under confinement; +and a loss of colour often occurs with brilliant males when they are +confined. With many species of herons the young differ greatly from the +adults; and the summer plumage of the latter, though common to both sexes, +clearly has a nuptial character. Young swans are slate-coloured, whilst +the mature birds are pure white; but it would be superfluous to give +additional instances. These differences between the young and the old +apparently depend, as in the last two classes, on the young having retained +a former or ancient state of plumage, whilst the old of both sexes have +acquired a new one. When the adults are bright coloured, we may conclude +from the remarks just made in relation to the scarlet ibis and to many +herons, and from the analogy of the species in the first class, that such +colours have been acquired through sexual selection by the nearly mature +males; but that, differently from what occurs in the first two classes, the +transmission, though limited to the same age, has not been limited to the +same sex. Consequently, the sexes when mature resemble each other and +differ from the young. + +CLASS IV. + +WHEN THE ADULT MALE RESEMBLES THE ADULT FEMALE, THE YOUNG OF BOTH SEXES IN +THEIR FIRST PLUMAGE RESEMBLE THE ADULTS. + +In this class the young and the adults of both sexes, whether brilliantly +or obscurely coloured, resemble each other. Such cases are, I think, more +common than those in the last class. We have in England instances in the +kingfisher, some woodpeckers, the jay, magpie, crow, and many small dull- +coloured birds, such as the hedge-warbler or kitty-wren. But the +similarity in plumage between the young and the old is never complete, and +graduates away into dissimilarity. Thus the young of some members of the +kingfisher family are not only less vividly coloured than the adults, but +many of the feathers on the lower surface are edged with brown (27. +Jerdon, 'Birds of India,' vol. i. pp. 222, 228. Gould's 'Handbook to the +Birds of Australia,' vol. i. pp. 124, 130.),--a vestige probably of a +former state of the plumage. Frequently in the same group of birds, even +within the same genus, for instance in an Australian genus of parrakeets +(Platycercus), the young of some species closely resemble, whilst the young +of other species differ considerably, from their parents of both sexes, +which are alike. (28. Gould, ibid. vol. ii. pp. 37, 46, 56.) Both sexes +and the young of the common jay are closely similar; but in the Canada jay +(Perisoreus canadensis) the young differ so much from their parents that +they were formerly described as distinct species. (29. Audubon, 'Ornith. +Biography,' vol. ii. p. 55.) + +I may remark before proceeding that, under the present and next two classes +of cases, the facts are so complex and the conclusions so doubtful, that +any one who feels no especial interest in the subject had better pass them +over. + +The brilliant or conspicuous colours which characterise many birds in the +present class, can rarely or never be of service to them as a protection; +so that they have probably been gained by the males through sexual +selection, and then transferred to the females and the young. It is, +however, possible that the males may have selected the more attractive +females; and if these transmitted their characters to their offspring of +both sexes, the same results would follow as from the selection of the more +attractive males by the females. But there is evidence that this +contingency has rarely, if ever, occurred in any of those groups of birds +in which the sexes are generally alike; for, if even a few of the +successive variations had failed to be transmitted to both sexes, the +females would have slightly exceeded the males in beauty. Exactly the +reverse occurs under nature; for, in almost every large group in which the +sexes generally resemble each other, the males of some few species are in a +slight degree more brightly coloured than the females. It is again +possible that the females may have selected the more beautiful males, these +males having reciprocally selected the more beautiful females; but it is +doubtful whether this double process of selection would be likely to occur, +owing to the greater eagerness of one sex than the other, and whether it +would be more efficient than selection on one side alone. It is, +therefore, the most probable view that sexual selection has acted, in the +present class, as far as ornamental characters are concerned, in accordance +with the general rule throughout the animal kingdom, that is, on the males; +and that these have transmitted their gradually-acquired colours, either +equally or almost equally, to their offspring of both sexes. + +Another point is more doubtful, namely, whether the successive variations +first appeared in the males after had become nearly mature, or whilst quite +young. In either case sexual selection must have acted on the male when he +had to compete with rivals for the possession of the female; and in both +cases the characters thus acquired have been transmitted to both sexes and +all ages. But these characters if acquired by the males when adult, may +have been transmitted at first to the adults alone, and at some subsequent +period transferred to the young. For it is known that, when the law of +inheritance at corresponding ages fails, the offspring often inherit +characters at an earlier age than that at which they first appeared in +their parents. (30. 'Variation of Animals and Plants under +Domestication,' vol. ii. p. 79.) Cases apparently of this kind have been +observed with birds in a state of nature. For instance Mr. Blyth has seen +specimens of Lanius rufus and of Colymbus glacialis which had assumed +whilst young, in a quite anomalous manner, the adult plumage of their +parents. (31. 'Charlesworth's Magazine of Natural History,' vol. i. 1837, +pp. 305, 306.) Again, the young of the common swan (Cygnus olor) do not +cast off their dark feathers and become white until eighteen months or two +years old; but Dr. F. Forel has described the case of three vigorous young +birds, out of a brood of four, which were born pure white. These young +birds were not albinos, as shewn by the colour of their beaks and legs, +which nearly resembled the same parts in the adults. (32. 'Bulletin de la +Soc. Vaudoise des Sc. Nat.' vol. x. 1869, p. 132. The young of the Polish +swan, Cygnus immutabilis of Yarrell, are always white; but this species, as +Mr. Sclater informs me, is believed to be nothing more than a variety of +the domestic swan (Cygnus olor).) + +It may be worth while to illustrate the above three modes by which, in the +present class, the two sexes and the young may have come to resemble each +other, by the curious case of the genus Passer. (33. I am indebted to Mr. +Blyth for information in regard to this genus. The sparrow of Palestine +belongs to the sub-genus Petronia.) In the house-sparrow (P. domesticus) +the male differs much from the female and from the young. The young and +the females are alike, and resemble to a large extent both sexes and the +young of the sparrow of Palestine (P. brachydactylus), as well as of some +allied species. We may therefore assume that the female and young of the +house-sparrow approximately shew us the plumage of the progenitor of the +genus. Now with the tree-sparrow (P. montanus) both sexes and the young +closely resemble the male of the house-sparrow; so that they have all been +modified in the same manner, and all depart from the typical colouring of +their early progenitor. This may have been effected by a male ancestor of +the tree-sparrow having varied, firstly, when nearly mature; or, secondly, +whilst quite young, and by having in either case transmitted his modified +plumage to the females and the young; or, thirdly, he may have varied when +adult and transmitted his plumage to both adult sexes, and, owing to the +failure of the law of inheritance at corresponding ages, at some subsequent +period to his young. + +It is impossible to decide which of these three modes has generally +prevailed throughout the present class of cases. That the males varied +whilst young, and transmitted their variations to their offspring of both +sexes, is the most probable. I may here add that I have, with little +success, endeavoured, by consulting various works, to decide how far the +period of variation in birds has generally determined the transmission of +characters to one sex or to both. The two rules, often referred to +(namely, that variations occurring late in life are transmitted to one and +the same sex, whilst those which occur early in life are transmitted to +both sexes), apparently hold good in the first (34. For instance, the +males of Tanagra aestiva and Fringilla cyanea require three years, the male +of Fringilla ciris four years, to complete their beautiful plumage. (See +Audubon, 'Ornith. Biography,' vol. i. pp. 233, 280, 378). The Harlequin +duck takes three years (ibid. vol. iii. p. 614). The male of the Gold +pheasant, as I hear from Mr. Jenner Weir, can be distinguished from the +female when about three months old, but he does not acquire his full +splendour until the end of the September in the following year.), second, +and fourth classes of cases; but they fail in the third, often in the fifth +(35. Thus the Ibis tantalus and Grus americanus take four years, the +Flamingo several years, and the Ardea ludovicana two years, before they +acquire their perfect plumage. See Audubon, ibid. vol. i. p. 221; vol. +iii. pp. 133, 139, 211.), and in the sixth small class. They apply, +however, as far as I can judge, to a considerable majority of the species; +and we must not forget the striking generalisation by Dr. W. Marshall with +respect to the protuberances on the heads of birds. Whether or not the two +rules generally hold good, we may conclude from the facts given in the +eighth chapter, that the period of variation is one important element in +determining the form of transmission. + +With birds it is difficult to decide by what standard we ought to judge of +the earliness or lateness of the period of variation, whether by the age in +reference to the duration of life, or to the power of reproduction, or to +the number of moults through which the species passes. The moulting of +birds, even within the same family, sometimes differs much without any +assignable cause. Some birds moult so early, that nearly all the body +feathers are cast off before the first wing-feathers are fully grown; and +we cannot believe that this was the primordial state of things. When the +period of moulting has been accelerated, the age at which the colours of +the adult plumage are first developed will falsely appear to us to be +earlier than it really is. This may be illustrated by the practice +followed by some bird-fanciers, who pull out a few feathers from the breast +of nestling bullfinches, and from the head or neck of young gold-pheasants, +in order to ascertain their sex; for in the males, these feathers are +immediately replaced by coloured ones. (36. Mr. Blyth, in Charlesworth's +'Magazine of Natural History,' vol. i. 1837, p. 300. Mr. Bartlett has +informed me in regard to gold pheasants.) The actual duration of life is +known in but few birds, so that we can hardly judge by this standard. And, +with reference to the period at which the power of reproduction is gained, +it is a remarkable fact that various birds occasionally breed whilst +retaining their immature plumage. (37. I have noticed the following cases +in Audubon's 'Ornith. Biography.' The redstart of America (Muscapica +ruticilla, vol. i. p. 203). The Ibis tantalus takes four years to come to +full maturity, but sometimes breeds in the second year (vol. iii. p. 133). +The Grus americanus takes the same time, but breeds before acquiring its +full plumage (vol. iii. p. 211). The adults of Ardea caerulea are blue, +and the young white; and white, mottled, and mature blue birds may all be +seen breeding together (vol. iv. p. 58): but Mr. Blyth informs me that +certain herons apparently are dimorphic, for white and coloured individuals +of the same age may be observed. The Harlequin duck (Anas histrionica, +Linn.) takes three years to acquire its full plumage, though many birds +breed in the second year (vol. iii. p. 614). The White-headed Eagle (Falco +leucocephalus, vol. iii. p. 210) is likewise known to breed in its immature +state. Some species of Oriolus (according to Mr. Blyth and Mr. Swinhoe, in +'Ibis,' July 1863, p. 68) likewise breed before they attain their full +plumage.) + +The fact of birds breeding in their immature plumage seems opposed to the +belief that sexual selection has played as important a part, as I believe +it has, in giving ornamental colours, plumes, etc., to the males, and, by +means of equal transmission, to the females of many species. The objection +would be a valid one, if the younger and less ornamented males were as +successful in winning females and propagating their kind, as the older and +more beautiful males. But we have no reason to suppose that this is the +case. Audubon speaks of the breeding of the immature males of Ibis +tantalus as a rare event, as does Mr. Swinhoe, in regard to the immature +males of Oriolus. (38. See footnote 37 above.) If the young of any +species in their immature plumage were more successful in winning partners +than the adults, the adult plumage would probably soon be lost, as the +males would prevail, which retained their immature dress for the longest +period, and thus the character of the species would ultimately be modified. +(39. Other animals, belonging to quite distinct classes, are either +habitually or occasionally capable of breeding before they have fully +acquired their adult characters. This is the case with the young males of +the salmon. Several amphibians have been known to breed whilst retaining +their larval structure. Fritz Müller has shewn ('Facts and arguments for +Darwin,' Eng. trans. 1869, p. 79) that the males of several amphipod +crustaceans become sexually mature whilst young; and I infer that this is a +case of premature breeding, because they have not as yet acquired their +fully-developed claspers. All such facts are highly interesting, as +bearing on one means by which species may undergo great modifications of +character.) If, on the other hand, the young never succeeded in obtaining +a female, the habit of early reproduction would perhaps be sooner or later +eliminated, from being superfluous and entailing waste of power. + +The plumage of certain birds goes on increasing in beauty during many years +after they are fully mature; this is the case with the train of the +peacock, with some of the birds of paradise, and with the crest and plumes +of certain herons, for instance, the Ardea ludovicana. (40. Jerdon, +'Birds of India,' vol. iii. p. 507, on the peacock. Dr. Marshall thinks +that the older and more brilliant males of birds of paradise, have an +advantage over the younger males; see 'Archives Neerlandaises,' tom. vi. +1871.--On Ardea, Audubon, ibid. vol. iii. p. 139.) But it is doubtful +whether the continued development of such feathers is the result of the +selection of successive beneficial variations (though this is the most +probable view with birds of paradise) or merely of continuous growth. Most +fishes continue increasing in size, as long as they are in good health and +have plenty of food; and a somewhat similar law may prevail with the plumes +of birds. + +CLASS V. + +WHEN THE ADULTS OF BOTH SEXES HAVE A DISTINCT WINTER AND SUMMER PLUMAGE, +WHETHER OR NOT THE MALE DIFFERS FROM THE FEMALE, THE YOUNG RESEMBLE THE +ADULTS OF BOTH SEXES IN THEIR WINTER DRESS, OR MUCH MORE RARELY IN THEIR +SUMMER DRESS, OR THEY RESEMBLE THE FEMALES ALONE. OR THE YOUNG MAY HAVE AN +INTERMEDIATE CHARACTER; OR, AGAIN, THEY MAY DIFFER GREATLY FROM THE ADULTS +IN BOTH THEIR SEASONAL PLUMAGES. + +The cases in this class are singularly complex; nor is this surprising, as +they depend on inheritance, limited in a greater or less degree in three +different ways, namely, by sex, age, and the season of the year. In some +cases the individuals of the same species pass through at least five +distinct states of plumage. With the species, in which the male differs +from the female during the summer season alone, or, which is rarer, during +both seasons (41. For illustrative cases, see vol. iv. of Macgillivray's +'History of British Birds;' on Tringa, etc., pp. 229, 271; on the Machetes, +p. 172; on the Charadrius hiaticula, p. 118; on the Charadrius pluvialis, +p. 94.), the young generally resemble the females,--as with the so-called +goldfinch of North America, and apparently with the splendid Maluri of +Australia. (42. For the goldfinch of N. America, Fringilla tristis, +Linn., see Audubon, 'Ornithological Biography,' vol. i. p. 172. For the +Maluri, Gould's 'Handbook of the Birds of Australia,' vol. i. p. 318.) +With those species, the sexes of which are alike during both the summer and +winter, the young may resemble the adults, firstly, in their winter dress; +secondly, and this is of much rarer occurrence, in their summer dress; +thirdly, they may be intermediate between these two states; and, fourthly, +they may differ greatly from the adults at all seasons. We have an +instance of the first of these four cases in one of the egrets of India +(Buphus coromandus), in which the young and the adults of both sexes are +white during the winter, the adults becoming golden-buff during the summer. + +With the gaper (Anastomus oscitans) of India we have a similar case, but +the colours are reversed: for the young and the adults of both sexes are +grey and black during the winter, the adults becoming white during the +summer. (43. I am indebted to Mr. Blyth for information as to the Buphus; +see also Jerdon, 'Birds of India,' vol. iii. p. 749. On the Anastomus, see +Blyth, in 'Ibis,' 1867, p. 173.) As an instance of the second case, the +young of the razor-bill (Alca torda, Linn.), in an early state of plumage, +are coloured like the adults during the summer; and the young of the white- +crowned sparrow of North America (Fringilla leucophrys), as soon as +fledged, have elegant white stripes on their heads, which are lost by the +young and the old during the winter. (44. On the Alca, see Macgillivray, +'Hist. Brit. Birds,' vol. v. p. 347. On the Fringilla leucophrys, Audubon, +ibid. vol. ii. p. 89. I shall have hereafter to refer to the young of +certain herons and egrets being white.) With respect to the third case, +namely, that of the young having an intermediate character between the +summer and winter adult plumages, Yarrell (45. 'History of British Birds,' +vol. i. 1839, p. 159.) insists that this occurs with many waders. Lastly, +in regard to the young differing greatly from both sexes in their adult +summer and winter plumages, this occurs with some herons and egrets of +North America and India,--the young alone being white. + +I will make only a few remarks on these complicated cases. When the young +resemble the females in their summer dress, or the adults of both sexes in +their winter dress, the cases differ from those given under Classes I. and +III. only in the characters originally acquired by the males during the +breeding-season, having been limited in their transmission to the +corresponding season. When the adults have a distinct summer and winter +plumage, and the young differ from both, the case is more difficult to +understand. We may admit as probable that the young have retained an +ancient state of plumage; we can account by sexual selection for the summer +or nuptial plumage of the adults, but how are we to account for their +distinct winter plumage? If we could admit that this plumage serves in all +cases as a protection, its acquirement would be a simple affair; but there +seems no good reason for this admission. It may be suggested that the +widely different conditions of life during the winter and summer have acted +in a direct manner on the plumage; this may have had some effect, but I +have not much confidence in so great a difference as we sometimes see +between the two plumages, having been thus caused. A more probable +explanation is, that an ancient style of plumage, partially modified +through the transference of some characters from the summer plumage, has +been retained by the adults during the winter. Finally, all the cases in +our present class apparently depend on characters acquired by the adult +males, having been variously limited in their transmission according to +age, season, and sex; but it would not be worth while to attempt to follow +out these complex relations. + +CLASS VI. + +THE YOUNG IN THEIR FIRST PLUMAGE DIFFER FROM EACH OTHER ACCORDING TO SEX; +THE YOUNG MALES RESEMBLING MORE OR LESS CLOSELY THE ADULT MALES, AND THE +YOUNG FEMALES MORE OR LESS CLOSELY THE ADULT FEMALES. + +The cases in the present class, though occurring in various groups, are not +numerous; yet it seems the most natural thing that the young should at +first somewhat resemble the adults of the same sex, and gradually become +more and more like them. The adult male blackcap (Sylvia atricapilla) has +a black head, that of the female being reddish-brown; and I am informed by +Mr. Blyth, that the young of both sexes can be distinguished by this +character even as nestlings. In the family of thrushes an unusual number +of similar cases have been noticed; thus, the male blackbird (Turdus +merula) can be distinguished in the nest from the female. The two sexes of +the mocking bird (Turdus polyglottus, Linn.) differ very little from each +other, yet the males can easily be distinguished at a very early age from +the females by showing more pure white. (46. Audubon, 'Ornith. +Biography,' vol. i. p. 113.) The males of a forest-thrush and of a rock- +thrush (Orocetes erythrogastra and Petrocincla cyanea) have much of their +plumage of a fine blue, whilst the females are brown; and the nestling +males of both species have their main wing and tail-feathers edged with +blue whilst those of the female are edged with brown. (47. Mr. C.A. +Wright, in 'Ibis,' vol. vi. 1864, p. 65. Jerdon, 'Birds of India,' vol. i. +p. 515. See also on the blackbird, Blyth in Charlesworth's 'Magazine of +Natural History,' vol. i. 1837, p. 113.) In the young blackbird the wing- +feathers assume their mature character and become black after the others; +on the other hand, in the two species just named the wing-feathers become +blue before the others. The most probable view with reference to the cases +in the present class is that the males, differently from what occurs in +Class I., have transmitted their colours to their male offspring at an +earlier age than that at which they were first acquired; for, if the males +had varied whilst quite young, their characters would probably have been +transmitted to both sexes. (48. The following additional cases may be +mentioned; the young males of Tanagra rubra can be distinguished from the +young females (Audubon, 'Ornith. Biography,' vol. iv. p. 392), and so it is +within the nestlings of a blue nuthatch, Dendrophila frontalis of India +(Jerdon, 'Birds of India,' vol. i. p. 389). Mr. Blyth also informs me that +the sexes of the stonechat, Saxicola rubicola, are distinguishable at a +very early age. Mr. Salvin gives ('Proc. Zoolog. Soc.' 1870, p. 206) the +case of a humming-bird, like the following one of Eustephanus.) + +In Aithurus polytmus, a humming-bird, the male is splendidly coloured black +and green, and two of the tail-feathers are immensely lengthened; the +female has an ordinary tail and inconspicuous colours; now the young males, +instead of resembling the adult female, in accordance with the common rule, +begin from the first to assume the colours proper to their sex, and their +tail-feathers soon become elongated. I owe this information to Mr. Gould, +who has given me the following more striking and as yet unpublished case. +Two humming-birds belonging to the genus Eustephanus, both beautifully +coloured, inhabit the small island of Juan Fernandez, and have always been +ranked as specifically distinct. But it has lately been ascertained that +the one which is of a rich chestnut-brown colour with a golden-red head, is +the male, whilst the other which is elegantly variegated with green and +white with a metallic green head is the female. Now the young from the +first somewhat resemble the adults of the corresponding sex, the +resemblance gradually becoming more and more complete. + +In considering this last case, if as before we take the plumage of the +young as our guide, it would appear that both sexes have been rendered +beautiful independently; and not that one sex has partially transferred its +beauty to the other. The male apparently has acquired his bright colours +through sexual selection in the same manner as, for instance, the peacock +or pheasant in our first class of cases; and the female in the same manner +as the female Rhynchaea or Turnix in our second class of cases. But there +is much difficulty in understanding how this could have been effected at +the same time with the two sexes of the same species. Mr. Salvin states, +as we have seen in the eighth chapter, that with certain humming-birds the +males greatly exceed the females in number, whilst with other species +inhabiting the same country the females greatly exceed the males. If, +then, we might assume that during some former lengthened period the males +of the Juan Fernandez species had greatly exceeded the females in number, +but that during another lengthened period the females had far exceeded the +males, we could understand how the males at one time, and the females at +another, might have been rendered beautiful by the selection of the +brighter coloured individuals of either sex; both sexes transmitting their +characters to their young at a rather earlier age than usual. Whether this +is the true explanation I will not pretend to say; but the case is too +remarkable to be passed over without notice. + +We have now seen in all six classes, that an intimate relation exists +between the plumage of the young and the adults, either of one sex or both. +These relations are fairly well explained on the principle that one sex-- +this being in the great majority of cases the male--first acquired through +variation and sexual selection bright colours or other ornaments, and +transmitted them in various ways, in accordance with the recognised laws of +inheritance. Why variations have occurred at different periods of life, +even sometimes with species of the same group, we do not know, but with +respect to the form of transmission, one important determining cause seems +to be the age at which the variations first appear. + +From the principle of inheritance at corresponding ages, and from any +variations in colour which occurred in the males at an early age not being +then selected--on the contrary being often eliminated as dangerous--whilst +similar variations occurring at or near the period of reproduction have +been preserved, it follows that the plumage of the young will often have +been left unmodified, or but little modified. We thus get some insight +into the colouring of the progenitors of our existing species. In a vast +number of species in five out of our six classes of cases, the adults of +one sex or of both are bright coloured, at least during the breeding- +season, whilst the young are invariably less brightly coloured than the +adults, or are quite dull coloured; for no instance is known, as far as I +can discover, of the young of dull-coloured species displaying bright +colours, or of the young of bright-coloured species being more brilliant +than their parents. In the fourth class, however, in which the young and +the old resemble each other, there are many species (though by no means +all), of which the young are bright-coloured, and as these form old groups, +we may infer that their early progenitors were likewise bright. With this +exception, if we look to the birds of the world, it appears that their +beauty has been much increased since that period, of which their immature +plumage gives us a partial record. + +ON THE COLOUR OF THE PLUMAGE IN RELATION TO PROTECTION. + +It will have been seen that I cannot follow Mr. Wallace in the belief that +dull colours, when confined to the females, have been in most cases +specially gained for the sake of protection. There can, however, be no +doubt, as formerly remarked, that both sexes of many birds have had their +colours modified, so as to escape the notice of their enemies; or in some +instances, so as to approach their prey unobserved, just as owls have had +their plumage rendered soft, that their flight may not be overheard. Mr. +Wallace remarks (49. 'Westminster Review,' July 1867, p. 5.) that "it is +only in the tropics, among forests which never lose their foliage, that we +find whole groups of birds, whose chief colour is green." It will be +admitted by every one, who has ever tried, how difficult it is to +distinguish parrots in a leaf-covered tree. Nevertheless, we must remember +that many parrots are ornamented with crimson, blue, and orange tints, +which can hardly be protective. Woodpeckers are eminently arboreal, but +besides green species, there are many black, and black-and-white kinds--all +the species being apparently exposed to nearly the same dangers. It is +therefore probable that with tree-haunting birds, strongly-pronounced +colours have been acquired through sexual selection, but that a green tint +has been acquired oftener than any other, from the additional advantage of +protection. + +In regard to birds which live on the ground, every one admits that they are +coloured so as to imitate the surrounding surface. How difficult it is to +see a partridge, snipe, woodcock, certain plovers, larks, and night-jars +when crouched on ground. Animals inhabiting deserts offer the most +striking cases, for the bare surface affords no concealment, and nearly all +the smaller quadrupeds, reptiles, and birds depend for safety on their +colours. Mr. Tristram has remarked in regard to the inhabitants of the +Sahara, that all are protected by their "isabelline or sand-colour." (50. +'Ibis,' 1859, vol. i. p. 429, et seq. Dr. Rohlfs, however, remarks to me +in a letter that according to his experience of the Sahara, this statement +is too strong.) Calling to my recollection the desert-birds of South +America, as well as most of the ground-birds of Great Britain, it appeared +to me that both sexes in such cases are generally coloured nearly alike. +Accordingly, I applied to Mr. Tristram with respect to the birds of the +Sahara, and he has kindly given me the following information. There are +twenty-six species belonging to fifteen genera, which manifestly have their +plumage coloured in a protective manner; and this colouring is all the more +striking, as with most of these birds it differs from that of their +congeners. Both sexes of thirteen out of the twenty-six species are +coloured in the same manner; but these belong to genera in which this rule +commonly prevails, so that they tell us nothing about the protective +colours being the same in both sexes of desert-birds. Of the other +thirteen species, three belong to genera in which the sexes usually differ +from each other, yet here they have the sexes alike. In the remaining ten +species, the male differs from the female; but the difference is confined +chiefly to the under surface of the plumage, which is concealed when the +bird crouches on the ground; the head and back being of the same sand- +coloured hue in the two sexes. So that in these ten species the upper +surfaces of both sexes have been acted on and rendered alike, through +natural selection, for the sake of protection; whilst the lower surfaces of +the males alone have been diversified, through sexual selection, for the +sake of ornament. Here, as both sexes are equally well protected, we +clearly see that the females have not been prevented by natural selection +from inheriting the colours of their male parents; so that we must look to +the law of sexually-limited transmission. + +In all parts of the world both sexes of many soft-billed birds, especially +those which frequent reeds or sedges, are obscurely coloured. No doubt if +their colours had been brilliant, they would have been much more +conspicuous to their enemies; but whether their dull tints have been +specially gained for the sake of protection seems, as far as I can judge, +rather doubtful. It is still more doubtful whether such dull tints can +have been gained for the sake of ornament. We must, however, bear in mind +that male birds, though dull-coloured, often differ much from their females +(as with the common sparrow), and this leads to the belief that such +colours have been gained through sexual selection, from being attractive. +Many of the soft-billed birds are songsters; and a discussion in a former +chapter should not be forgotten, in which it was shewn that the best +songsters are rarely ornamented with bright tints. It would appear that +female birds, as a general rule, have selected their mates either for their +sweet voices or gay colours, but not for both charms combined. Some +species, which are manifestly coloured for the sake of protection, such as +the jack-snipe, woodcock, and night-jar, are likewise marked and shaded, +according to our standard of taste, with extreme elegance. In such cases +we may conclude that both natural and sexual selection have acted +conjointly for protection and ornament. Whether any bird exists which does +not possess some special attraction, by which to charm the opposite sex, +may be doubted. When both sexes are so obscurely coloured that it would be +rash to assume the agency of sexual selection, and when no direct evidence +can be advanced shewing that such colours serve as a protection, it is best +to own complete ignorance of the cause, or, which comes to nearly the same +thing, to attribute the result to the direct action of the conditions of +life. + +Both sexes of many birds are conspicuously, though not brilliantly +coloured, such as the numerous black, white, or piebald species; and these +colours are probably the result of sexual selection. With the common +blackbird, capercailzie, blackcock, black scoter-duck (Oidemia), and even +with one of the birds of paradise (Lophorina atra), the males alone are +black, whilst the females are brown or mottled; and there can hardly be a +doubt that blackness in these cases has been a sexually selected character. +Therefore it is in some degree probable that the complete or partial +blackness of both sexes in such birds as crows, certain cockatoos, storks, +and swans, and many marine birds, is likewise the result of sexual +selection, accompanied by equal transmission to both sexes; for blackness +can hardly serve in any case as a protection. With several birds, in which +the male alone is black, and in others in which both sexes are black, the +beak or skin about the head is brightly coloured, and the contrast thus +afforded adds much to their beauty; we see this in the bright yellow beak +of the male blackbird, in the crimson skin over the eyes of the blackcock +and capercailzie, in the brightly and variously coloured beak of the +scoter-drake (Oidemia), in the red beak of the chough (Corvus graculus, +Linn.), of the black swan, and the black stork. This leads me to remark +that it is not incredible that toucans may owe the enormous size of their +beaks to sexual selection, for the sake of displaying the diversified and +vivid stripes of colour, with which these organs are ornamented. (51. No +satisfactory explanation has ever been offered of the immense size, and +still less of the bright colours, of the toucan's beak. Mr. Bates ('The +Naturalist on the Amazons,' vol. ii. 1863, p. 341) states that they use +their beaks for reaching fruit at the extreme tips of the branches; and +likewise, as stated by other authors, for extracting eggs and young birds +from the nests of other birds. But, as Mr. Bates admits, the beak "can +scarcely be considered a very perfectly-formed instrument for the end to +which it is applied." The great bulk of the beak, as shewn by its breadth, +depth, as well as length, is not intelligible on the view, that it serves +merely as an organ of prehension. Mr. Belt believes ('The Naturalist in +Nicaragua,' p. 197) that the principal use of the beak is as a defence +against enemies, especially to the female whilst nesting in a hole in a +tree.) The naked skin, also, at the base of the beak and round the eyes is +likewise often brilliantly coloured; and Mr. Gould, in speaking of one +species (52. Rhamphastos carinatus, Gould's 'Monograph of Ramphastidae.'), +says that the colours of the beak "are doubtless in the finest and most +brilliant state during the time of pairing." There is no greater +improbability that toucans should be encumbered with immense beaks, though +rendered as light as possible by their cancellated structure, for the +display of fine colours (an object falsely appearing to us unimportant), +than that the male Argus pheasant and some other birds should be encumbered +with plumes so long as to impede their flight. + +In the same manner, as the males alone of various species are black, the +females being dull-coloured; so in a few cases the males alone are either +wholly or partially white, as with the several bell-birds of South America +(Chasmorhynchus), the Antarctic goose (Bernicla antarctica), the silver +pheasant, etc., whilst the females are brown or obscurely mottled. +Therefore, on the same principle as before, it is probable that both sexes +of many birds, such as white cockatoos, several egrets with their beautiful +plumes, certain ibises, gulls, terns, etc., have acquired their more or +less completely white plumage through sexual selection. In some of these +cases the plumage becomes white only at maturity. This is the case with +certain gannets, tropic-birds, etc., and with the snow-goose (Anser +hyperboreus). As the latter breeds on the "barren grounds," when not +covered with snow, and as it migrates southward during the winter, there is +no reason to suppose that its snow-white adult plumage serves as a +protection. In the Anastomus oscitans, we have still better evidence that +the white plumage is nuptial character, for it is developed only during the +summer; the young in their immature state, and the adults in their winter +dress, being grey and black. With many kinds of gulls (Larus), the head +and neck become pure white during the summer, being grey or mottled during +the winter and in the young state. On the other hand, with the smaller +gulls, or sea-mews (Gavia), and with some terns (Sterna), exactly the +reverse occurs; for the heads of the young birds during the first year, and +of the adults during the winter, are either pure white, or much paler +coloured than during the breeding-season. These latter cases offer another +instance of the capricious manner in which sexual selection appears often +to have acted. (53. On Larus, Gavia, and Sterna, see Macgillivray, +'History of British Birds,' vol. v. pp. 515, 584, 626. On the Anser +hyperboreus, Audubon, 'Ornithological Biography,' vol. iv. p. 562. On the +Anastomus, Mr. Blyth, in 'Ibis,' 1867, p. 173.) + +That aquatic birds have acquired a white plumage so much oftener than +terrestrial birds, probably depends on their large size and strong powers +of flight, so that they can easily defend themselves or escape from birds +of prey, to which moreover they are not much exposed. Consequently, sexual +selection has not here been interfered with or guided for the sake of +protection. No doubt with birds which roam over the open ocean, the males +and females could find each other much more easily, when made conspicuous +either by being perfectly white or intensely black; so that these colours +may possible serve the same end as the call-notes of many land-birds. (54. +It may be noticed that with vultures, which roam far and wide high in the +air, like marine birds over the ocean, three or four species are almost +wholly or largely white, and that many others are black. So that here +again conspicuous colours may possibly aid the sexes in finding each other +during the breeding-season.) A white or black bird when it discovers and +flies down to a carcase floating on the sea or cast up on the beach, will +be seen from a great distance, and will guide other birds of the same and +other species, to the prey; but as this would be a disadvantage to the +first finders, the individuals which were the whitest or blackest would not +thus procure more food than the less strongly coloured individuals. Hence +conspicuous colours cannot have been gradually acquired for this purpose +through natural selection. + +As sexual selection depends on so fluctuating an element as taste, we can +understand how it is that, within the same group of birds having nearly the +same habits, there should exist white or nearly white, as well as black, or +nearly black species,--for instance, both white and black cockatoos, +storks, ibises, swans, terns, and petrels. Piebald birds likewise +sometimes occur in the same groups together with black and white species; +for instance, the black-necked swan, certain terns, and the common magpie. +That a strong contrast in colour is agreeable to birds, we may conclude by +looking through any large collection, for the sexes often differ from each +other in the male having the pale parts of a purer white, and the variously +coloured dark parts of still darker tints than the female. + +It would even appear that mere novelty, or slight changes for the sake of +change, have sometimes acted on female birds as a charm, like changes of +fashion with us. Thus the males of some parrots can hardly be said to be +more beautiful than the females, at least according to our taste, but they +differ in such points, as in having a rose-coloured collar instead of "a +bright emeraldine narrow green collar"; or in the male having a black +collar instead of "a yellow demi-collar in front," with a pale roseate +instead of a plum-blue head. (55. See Jerdon on the genus Palaeornis, +'Birds of India,' vol. i. pp. 258-260.) As so many male birds have +elongated tail-feathers or elongated crests for their chief ornament, the +shortened tail, formerly described in the male of a humming-bird, and the +shortened crest of the male goosander, seem like one of the many changes of +fashion which we admire in our own dresses. + +Some members of the heron family offer a still more curious case of novelty +in colouring having, as it appears, been appreciated for the sake of +novelty. The young of the Ardea asha are white, the adults being dark +slate-coloured; and not only the young, but the adults in their winter +plumage, of the allied Buphus coromandus are white, this colour changing +into a rich golden-buff during the breeding-season. It is incredible that +the young of these two species, as well as of some other members of the +same family (56. The young of Ardea rufescens and A. caerulea of the +United States are likewise white, the adults being coloured in accordance +with their specific names. Audubon ('Ornithological Biography,' vol. iii. +p. 416; vol. iv. p. 58) seems rather pleased at the thought that this +remarkable change of plumage will greatly "disconcert the systematists."), +should for any special purpose have been rendered pure white and thus made +conspicuous to their enemies; or that the adults of one of these two +species should have been specially rendered white during the winter in a +country which is never covered with snow. On the other hand we have good +reason to believe that whiteness has been gained by many birds as a sexual +ornament. We may therefore conclude that some early progenitor of the +Ardea asha and the Buphus acquired a white plumage for nuptial purposes, +and transmitted this colour to their young; so that the young and the old +became white like certain existing egrets; and that the whiteness was +afterwards retained by the young, whilst it was exchanged by the adults for +more strongly-pronounced tints. But if we could look still further back to +the still earlier progenitors of these two species, we should probably see +the adults dark-coloured. I infer that this would be the case, from the +analogy of many other birds, which are dark whilst young, and when adult +are white; and more especially from the case of the Ardea gularis, the +colours of which are the reverse of those of A. asha, for the young are +dark-coloured and the adults white, the young having retained a former +state of plumage. It appears therefore that, during a long line of +descent, the adult progenitors of the Ardea asha, the Buphus, and of some +allies, have undergone the following changes of colour: first, a dark +shade; secondly, pure white; and thirdly, owing to another change of +fashion (if I may so express myself), their present slaty, reddish, or +golden-buff tints. These successive changes are intelligible only on the +principle of novelty having been admired by birds for its own sake. + +Several writers have objected to the whole theory of sexual selection, by +assuming that with animals and savages the taste of the female for certain +colours or other ornaments would not remain constant for many generations; +that first one colour and then another would be admired, and consequently +that no permanent effect could be produced. We may admit that taste is +fluctuating, but it is not quite arbitrary. It depends much on habit, as +we see in mankind; and we may infer that this would hold good with birds +and other animals. Even in our own dress, the general character lasts +long, and the changes are to a certain extent graduated. Abundant evidence +will be given in two places in a future chapter, that savages of many races +have admired for many generations the same cicatrices on the skin, the same +hideously perforated lips, nostrils, or ears, distorted heads, etc.; and +these deformities present some analogy to the natural ornaments of various +animals. Nevertheless, with savages such fashions do not endure for ever, +as we may infer from the differences in this respect between allied tribes +on the same continent. So again the raisers of fancy animals certainly +have admired for many generations and still admire the same breeds; they +earnestly desire slight changes, which are considered as improvements, but +any great or sudden change is looked at as the greatest blemish. With +birds in a state of nature we have no reason to suppose that they would +admire an entirely new style of coloration, even if great and sudden +variations often occurred, which is far from being the case. We know that +dovecot pigeons do not willingly associate with the variously coloured +fancy breeds; that albino birds do not commonly get partners in marriage; +and that the black ravens of the Feroe Islands chase away their piebald +brethren. But this dislike of a sudden change would not preclude their +appreciating slight changes, any more than it does in the case of man. +Hence with respect to taste, which depends on many elements, but partly on +habit and partly on a love of novelty, there seems no improbability in +animals admiring for a very long period the same general style of +ornamentation or other attractions, and yet appreciating slight changes in +colours, form, or sound. + +SUMMARY OF THE FOUR CHAPTERS ON BIRDS. + +Most male birds are highly pugnacious during the breeding-season, and some +possess weapons adapted for fighting with their rivals. But the most +pugnacious and the best armed males rarely or never depend for success +solely on their power to drive away or kill their rivals, but have special +means for charming the female. With some it is the power of song, or of +giving forth strange cries, or instrumental music, and the males in +consequence differ from the females in their vocal organs, or in the +structure of certain feathers. From the curiously diversified means for +producing various sounds, we gain a high idea of the importance of this +means of courtship. Many birds endeavour to charm the females by love- +dances or antics, performed on the ground or in the air, and sometimes at +prepared places. But ornaments of many kinds, the most brilliant tints, +combs and wattles, beautiful plumes, elongated feathers, top-knots, and so +forth, are by far the commonest means. In some cases mere novelty appears +to have acted as a charm. The ornaments of the males must be highly +important to them, for they have been acquired in not a few cases at the +cost of increased danger from enemies, and even at some loss of power in +fighting with their rivals. The males of very many species do not assume +their ornamental dress until they arrive at maturity, or they assume it +only during the breeding-season, or the tints then become more vivid. +Certain ornamental appendages become enlarged, turgid, and brightly +coloured during the act of courtship. The males display their charms with +elaborate care and to the best effect; and this is done in the presence of +the females. The courtship is sometimes a prolonged affair, and many males +and females congregate at an appointed place. To suppose that the females +do not appreciate the beauty of the males, is to admit that their splendid +decorations, all their pomp and display, are useless; and this is +incredible. Birds have fine powers of discrimination, and in some few +instances it can be shewn that they have a taste for the beautiful. The +females, moreover, are known occasionally to exhibit a marked preference or +antipathy for certain individual males. + +If it be admitted that the females prefer, or are unconsciously excited by +the more beautiful males, then the males would slowly but surely be +rendered more and more attractive through sexual selection. That it is +this sex which has been chiefly modified, we may infer from the fact that, +in almost every genus where the sexes differ, the males differ much more +from one another than do the females; this is well shewn in certain +closely-allied representative species, in which the females can hardly be +distinguished, whilst the males are quite distinct. Birds in a state of +nature offer individual differences which would amply suffice for the work +of sexual selection; but we have seen that they occasionally present more +strongly marked variations which recur so frequently that they would +immediately be fixed, if they served to allure the female. The laws of +variation must determine the nature of the initial changes, and will have +largely influenced the final result. The gradations, which may be observed +between the males of allied species, indicate the nature of the steps +through which they have passed. They explain also in the most interesting +manner how certain characters have originated, such as the indented ocelli +on the tail-feathers of the peacock, and the ball-and-socket ocelli on the +wing-feathers of the Argus pheasant. It is evident that the brilliant +colours, top-knots, fine plumes, etc., of many male birds cannot have been +acquired as a protection; indeed, they sometimes lead to danger. That they +are not due to the direct and definite action of the conditions of life, we +may feel assured, because the females have been exposed to the same +conditions, and yet often differ from the males to an extreme degree. +Although it is probable that changed conditions acting during a lengthened +period have in some cases produced a definite effect on both sexes, or +sometimes on one sex alone, the more important result will have been an +increased tendency to vary or to present more strongly-marked individual +differences; and such differences will have afforded an excellent ground- +work for the action of sexual selection. + +The laws of inheritance, irrespectively of selection, appear to have +determined whether the characters acquired by the males for the sake of +ornament, for producing various sounds, and for fighting together, have +been transmitted to the males alone or to both sexes, either permanently, +or periodically during certain seasons of the year. Why various characters +should have been transmitted sometimes in one way and sometimes in another, +is not in most cases known; but the period of variability seems often to +have been the determining cause. When the two sexes have inherited all +characters in common they necessarily resemble each other; but as the +successive variations may be differently transmitted, every possible +gradation may be found, even within the same genus, from the closest +similarity to the widest dissimilarity between the sexes. With many +closely-allied species, following nearly the same habits of life, the males +have come to differ from each other chiefly through the action of sexual +selection; whilst the females have come to differ chiefly from partaking +more or less of the characters thus acquired by the males. The effects, +moreover, of the definite action of the conditions of life, will not have +been masked in the females, as in the males, by the accumulation through +sexual selection of strongly-pronounced colours and other ornaments. The +individuals of both sexes, however affected, will have been kept at each +successive period nearly uniform by the free intercrossing of many +individuals. + +With species, in which the sexes differ in colour, it is possible or +probable that some of the successive variations often tended to be +transmitted equally to both sexes; but that when this occurred the females +were prevented from acquiring the bright colours of the males, by the +destruction which they suffered during incubation. There is no evidence +that it is possible by natural selection to convert one form of +transmission into another. But there would not be the least difficulty in +rendering a female dull-coloured, the male being still kept bright- +coloured, by the selection of successive variations, which were from the +first limited in their transmission to the same sex. Whether the females +of many species have actually been thus modified, must at present remain +doubtful. When, through the law of the equal transmission of characters to +both sexes, the females were rendered as conspicuously coloured as the +males, their instincts appear often to have been modified so that they were +led to build domed or concealed nests. + +In one small and curious class of cases the characters and habits of the +two sexes have been completely transposed, for the females are larger, +stronger, more vociferous and brighter coloured than the males. They have, +also, become so quarrelsome that they often fight together for the +possession of the males, like the males of other pugnacious species for the +possession of the females. If, as seems probable, such females habitually +drive away their rivals, and by the display of their bright colours or +other charms endeavour to attract the males, we can understand how it is +that they have gradually been rendered, by sexual selection and sexually- +limited transmission, more beautiful than the males--the latter being left +unmodified or only slightly modified. + +Whenever the law of inheritance at corresponding ages prevails but not that +of sexually-limited transmission, then if the parents vary late in life-- +and we know that this constantly occurs with our poultry, and occasionally +with other birds--the young will be left unaffected, whilst the adults of +both sexes will be modified. If both these laws of inheritance prevail and +either sex varies late in life, that sex alone will be modified, the other +sex and the young being unaffected. When variations in brightness or in +other conspicuous characters occur early in life, as no doubt often +happens, they will not be acted on through sexual selection until the +period of reproduction arrives; consequently if dangerous to the young, +they will be eliminated through natural selection. Thus we can understand +how it is that variations arising late in life have so often been preserved +for the ornamentation of the males; the females and the young being left +almost unaffected, and therefore like each other. With species having a +distinct summer and winter plumage, the males of which either resemble or +differ from the females during both seasons or during the summer alone, the +degrees and kinds of resemblance between the young and the old are +exceedingly complex; and this complexity apparently depends on characters, +first acquired by the males, being transmitted in various ways and degrees, +as limited by age, sex, and season. + +As the young of so many species have been but little modified in colour and +in other ornaments, we are enabled to form some judgment with respect to +the plumage of their early progenitors; and we may infer that the beauty of +our existing species, if we look to the whole class, has been largely +increased since that period, of which the immature plumage gives us an +indirect record. Many birds, especially those which live much on the +ground, have undoubtedly been obscurely coloured for the sake of +protection. In some instances the upper exposed surface of the plumage has +been thus coloured in both sexes, whilst the lower surface in the males +alone has been variously ornamented through sexual selection. Finally, +from the facts given in these four chapters, we may conclude that weapons +for battle, organs for producing sound, ornaments of many kinds, bright and +conspicuous colours, have generally been acquired by the males through +variation and sexual selection, and have been transmitted in various ways +according to the several laws of inheritance--the females and the young +being left comparatively but little modified. (57. I am greatly indebted +to the kindness of Mr. Sclater for having looked over these four chapters +on birds, and the two following ones on mammals. In this way I have been +saved from making mistakes about the names of the species, and from stating +anything as a fact which is known to this distinguished naturalist to be +erroneous. But, of course, he is not at all answerable for the accuracy of +the statements quoted by me from various authorities.) + + +CHAPTER XVII. + +SECONDARY SEXUAL CHARACTERS OF MAMMALS. + +The law of battle--Special weapons, confined to the males--Cause of absence +of weapons in the female--Weapons common to both sexes, yet primarily +acquired by the male--Other uses of such weapons--Their high importance-- +Greater size of the male--Means of defence--On the preference shown by +either sex in the pairing of quadrupeds. + +With mammals the male appears to win the female much more through the law +of battle than through the display of his charms. The most timid animals, +not provided with any special weapons for fighting, engage in desperate +conflicts during the season of love. Two male hares have been seen to +fight together until one was killed; male moles often fight, and sometimes +with fatal results; male squirrels engage in frequent contests, "and often +wound each other severely"; as do male beavers, so that "hardly a skin is +without scars." (1. See Waterton's account of two hares fighting, +'Zoologist,' vol. i. 1843, p. 211. On moles, Bell, 'Hist. of British +Quadrupeds,' 1st ed., p. 100. On squirrels, Audubon and Bachman, +Viviparous Quadrupeds of N. America, 1846, p. 269. On beavers, Mr. A.H. +Green, in 'Journal of Linnean Society, Zoology,' vol. x. 1869, p. 362.) I +observed the same fact with the hides of the guanacoes in Patagonia; and on +one occasion several were so absorbed in fighting that they fearlessly +rushed close by me. Livingstone speaks of the males of the many animals in +Southern Africa as almost invariably shewing the scars received in former +contests. + +The law of battle prevails with aquatic as with terrestrial mammals. It is +notorious how desperately male seals fight, both with their teeth and +claws, during the breeding-season; and their hides are likewise often +covered with scars. Male sperm-whales are very jealous at this season; and +in their battles "they often lock their jaws together, and turn on their +sides and twist about"; so that their lower jaws often become distorted. +(2. On the battles of seals, see Capt. C. Abbott in 'Proc. Zool. Soc.' +1868, p. 191; Mr. R. Brown, ibid. 1868, p. 436; also L. Lloyd, 'Game Birds +of Sweden,' 1867, p. 412; also Pennant. On the sperm-whale see Mr. J.H. +Thompson, in 'Proc. Zool. Soc.' 1867, p. 246.) + +All male animals which are furnished with special weapons for fighting, are +well known to engage in fierce battles. The courage and the desperate +conflicts of stags have often been described; their skeletons have been +found in various parts of the world, with the horns inextricably locked +together, shewing how miserably the victor and vanquished had perished. +(3. See Scrope ('Art of Deer-stalking,' p. 17) on the locking of the horns +with the Cervus elaphus. Richardson, in 'Fauna Bor. Americana,' 1829, p. +252, says that the wapiti, moose, and reindeer have been found thus locked +together. Sir. A. Smith found at the Cape of Good Hope the skeletons of +two gnus in the same condition.) No animal in the world is so dangerous as +an elephant in must. Lord Tankerville has given me a graphic description +of the battles between the wild bulls in Chillingham Park, the descendants, +degenerated in size but not in courage, of the gigantic Bos primigenius. +In 1861 several contended for mastery; and it was observed that two of the +younger bulls attacked in concert the old leader of the herd, overthrew and +disabled him, so that he was believed by the keepers to be lying mortally +wounded in a neighbouring wood. But a few days afterwards one of the young +bulls approached the wood alone; and then the "monarch of the chase," who +had been lashing himself up for vengeance, came out and, in a short time, +killed his antagonist. He then quietly joined the herd, and long held +undisputed sway. Admiral Sir B.J. Sulivan informs me that, when he lived +in the Falkland Islands, he imported a young English stallion, which +frequented the hills near Port William with eight mares. On these hills +there were two wild stallions, each with a small troop of mares; "and it is +certain that these stallions would never have approached each other without +fighting. Both had tried singly to fight the English horse and drive away +his mares, but had failed. One day they came in TOGETHER and attacked him. +This was seen by the capitan who had charge of the horses, and who, on +riding to the spot, found one of the two stallions engaged with the English +horse, whilst the other was driving away the mares, and had already +separated four from the rest. The capitan settled the matter by driving +the whole party into the corral, for the wild stallions would not leave the +mares." + +Male animals which are provided with efficient cutting or tearing teeth for +the ordinary purposes of life, such as the carnivora, insectivora, and +rodents, are seldom furnished with weapons especially adapted for fighting +with their rivals. The case is very different with the males of many other +animals. We see this in the horns of stags and of certain kinds of +antelopes in which the females are hornless. With many animals the canine +teeth in the upper or lower jaw, or in both, are much larger in the males +than in the females, or are absent in the latter, with the exception +sometimes of a hidden rudiment. Certain antelopes, the musk-deer, camel, +horse, boar, various apes, seals, and the walrus, offer instances. In the +females of the walrus the tusks are sometimes quite absent. (4. Mr. +Lamont ('Seasons with the Sea-Horses,' 1861, p. 143) says that a good tusk +of the male walrus weighs 4 pounds, and is longer than that of the female, +which weighs about 3 pounds. The males are described as fighting +ferociously. On the occasional absence of the tusks in the female, see Mr. +R. Brown, 'Proceedings, Zoological Society,' 1868, p. 429.) In the male +elephant of India and in the male dugong (5. Owen, 'Anatomy of +Vertebrates,' vol. iii. p. 283.) the upper incisors form offensive weapons. +In the male narwhal the left canine alone is developed into the well-known, +spirally-twisted, so-called horn, which is sometimes from nine to ten feet +in length. It is believed that the males use these horns for fighting +together; for "an unbroken one can rarely be got, and occasionally one may +be found with the point of another jammed into the broken place." (6. Mr. +R. Brown, in 'Proc. Zool. Soc.' 1869, p. 553. See Prof. Turner, in +'Journal of Anat. and Phys.' 1872, p. 76, on the homological nature of +these tusks. Also Mr. J.W. Clarke on two tusks being developed in the +males, in 'Proceedings of the Zoological Society,' 1871, p. 42.) The tooth +on the opposite side of the head in the male consists of a rudiment about +ten inches in length, which is embedded in the jaw; but sometimes, though +rarely, both are equally developed on the two sides. In the female both +are always rudimentary. The male cachalot has a larger head than that of +the female, and it no doubt aids him in his aquatic battles. Lastly, the +adult male ornithorhynchus is provided with a remarkable apparatus, namely +a spur on the foreleg, closely resembling the poison-fang of a venomous +snake; but according to Harting, the secretion from the gland is not +poisonous; and on the leg of the female there is a hollow, apparently for +the reception of the spur. (7. Owen on the cachalot and Ornithorhynchus, +ibid. vol. iii. pp. 638, 641. Harting is quoted by Dr. Zouteveen in the +Dutch translation of this work, vol. ii. p. 292.) + +When the males are provided with weapons which in the females are absent, +there can be hardly a doubt that these serve for fighting with other males; +and that they were acquired through sexual selection, and were transmitted +to the male sex alone. It is not probable, at least in most cases, that +the females have been prevented from acquiring such weapons, on account of +their being useless, superfluous, or in some way injurious. On the +contrary, as they are often used by the males for various purposes, more +especially as a defence against their enemies, it is a surprising fact that +they are so poorly developed, or quite absent, in the females of so many +animals. With female deer the development during each recurrent season of +great branching horns, and with female elephants the development of immense +tusks, would be a great waste of vital power, supposing that they were of +no use to the females. Consequently, they would have tended to be +eliminated in the female through natural selection; that is, if the +successive variations were limited in their transmission to the female sex, +for otherwise the weapons of the males would have been injuriously +affected, and this would have been a greater evil. On the whole, and from +the consideration of the following facts, it seems probable that when the +various weapons differ in the two sexes, this has generally depended on the +kind of transmission which has prevailed. + +As the reindeer is the one species in the whole family of Deer, in which +the female is furnished with horns, though they are somewhat smaller, +thinner, and less branched than in the male, it might naturally be thought +that, at least in this case, they must be of some special service to her. +The female retains her horns from the time when they are fully developed, +namely, in September, throughout the winter until April or May, when she +brings forth her young. Mr. Crotch made particular enquiries for me in +Norway, and it appears that the females at this season conceal themselves +for about a fortnight in order to bring forth their young, and then +reappear, generally hornless. In Nova Scotia, however, as I hear from Mr. +H. Reeks, the female sometimes retains her horns longer. The male on the +other hand casts his horns much earlier, towards the end of November. As +both sexes have the same requirements and follow the same habits of life, +and as the male is destitute of horns during the winter, it is improbable +that they can be of any special service to the female during this season, +which includes the larger part of the time during which she is horned. Nor +is it probable that she can have inherited horns from some ancient +progenitor of the family of deer, for, from the fact of the females of so +many species in all quarters of the globe not having horns, we may conclude +that this was the primordial character of the group. (8. On the structure +and shedding of the horns of the reindeer, Hoffberg, 'Amoenitates Acad.' +vol. iv. 1788, p. 149. See Richardson, 'Fauna Bor. Americana,' p. 241, in +regard to the American variety or species: also Major W. Ross King, 'The +Sportsman in Canada,' 1866, p. 80. + +The horns of the reindeer are developed at a most unusually early age; but +what the cause of this may be is not known. The effect has apparently been +the transference of the horns to both sexes. We should bear in mind that +horns are always transmitted through the female, and that she has a latent +capacity for their development, as we see in old or diseased females. (9. +Isidore Geoffroy St.-Hilaire, 'Essais de Zoolog. Générale,' 1841, p. 513. +Other masculine characters, besides the horns, are sometimes similarly +transferred to the female; thus Mr. Boner, in speaking of an old female +chamois ('Chamois Hunting in the Mountains of Bavaria,' 1860, 2nd ed., p. +363), says, "not only was the head very male-looking, but along the back +there was a ridge of long hair, usually to be found only in bucks.") +Moreover the females of some other species of deer exhibit, either normally +or occasionally, rudiments of horns; thus the female of Cervulus moschatus +has "bristly tufts, ending in a knob, instead of a horn"; and "in most +specimens of the female wapiti (Cervus canadensis) there is a sharp bony +protuberance in the place of the horn." (10. On the Cervulus, Dr. Gray, +'Catalogue of Mammalia in the British Museum,' part iii. p. 220. On the +Cervus canadensis or wapiti, see Hon. J.D. Caton, 'Ottawa Academy of Nat. +Sciences,' May 1868, p. 9.) From these several considerations we may +conclude that the possession of fairly well-developed horns by the female +reindeer, is due to the males having first acquired them as weapons for +fighting with other males; and secondarily to their development from some +unknown cause at an unusually early age in the males, and their consequent +transference to both sexes. + +Turning to the sheath-horned ruminants: with antelopes a graduated series +can be formed, beginning with species, the females of which are completely +destitute of horns--passing on to those which have horns so small as to be +almost rudimentary (as with the Antilocapra americana, in which species +they are present in only one out of four or five females (11. I am +indebted to Dr. Canfield for this information; see also his paper in the +'Proceedings of the Zoological Society,' 1866, p. 105.))--to those which +have fairly developed horns, but manifestly smaller and thinner than in the +male and sometimes of a different shape (12. For instance the horns of the +female Ant. euchore resemble those of a distinct species, viz. the Ant. +dorcas var. Corine, see Desmarest, 'Mammalogie,' p. 455.),--and ending with +those in which both sexes have horns of equal size. As with the reindeer, +so with antelopes, there exists, as previously shewn, a relation between +the period of the development of the horns and their transmission to one or +both sexes; it is therefore probable that their presence or absence in the +females of some species, and their more or less perfect condition in the +females of other species, depends, not on their being of any special use, +but simply on inheritance. It accords with this view that even in the same +restricted genus both sexes of some species, and the males alone of others, +are thus provided. It is also a remarkable fact that, although the females +of Antilope bezoartica are normally destitute of horns, Mr. Blyth has seen +no less than three females thus furnished; and there was no reason to +suppose that they were old or diseased. + +In all the wild species of goats and sheep the horns are larger in the male +than in the female, and are sometimes quite absent in the latter. (13. +Gray, 'Catalogue of Mammalia, the British Museum,' part iii. 1852, p. 160.) +In several domestic breeds of these two animals, the males alone are +furnished with horns; and in some breeds, for instance, in the sheep of +North Wales, though both sexes are properly horned, the ewes are very +liable to be hornless. I have been informed by a trustworthy witness, who +purposely inspected a flock of these same sheep during the lambing season, +that the horns at birth are generally more fully developed in the male than +in the female. Mr. J. Peel crossed his Lonk sheep, both sexes of which +always bear horns, with hornless Leicesters and hornless Shropshire Downs; +and the result was that the male offspring had their horns considerably +reduced, whilst the females were wholly destitute of them. These several +facts indicate that, with sheep, the horns are a much less firmly fixed +character in the females than in the males; and this leads us to look at +the horns as properly of masculine origin. + +With the adult musk-ox (Ovibos moschatus) the horns of the male are larger +than those of the female, and in the latter the bases do not touch. (14. +Richardson, 'Fauna Bor. Americana,' p. 278.) In regard to ordinary cattle +Mr. Blyth remarks: "In most of the wild bovine animals the horns are both +longer and thicker in the bull than in the cow, and in the cow-banteng (Bos +sondaicus) the horns are remarkably small, and inclined much backwards. In +the domestic races of cattle, both of the humped and humpless types, the +horns are short and thick in the bull, longer and more slender in the cow +and ox; and in the Indian buffalo, they are shorter and thicker in the +bull, longer and more slender in the cow. In the wild gaour (B. gaurus) +the horns are mostly both longer and thicker in the bull than in the cow." +(15. 'Land and Water,' 1867, p. 346.) Dr. Forsyth Major also informs me +that a fossil skull, believed to be that of the female Bos etruscus, has +been found in Val d'Arno, which is wholly without horns. In the Rhinoceros +simus, as I may add, the horns of the female are generally longer but less +powerful than in the male; and in some other species of rhinoceros they are +said to be shorter in the female. (16. Sir Andrew Smith, 'Zoology of S. +Africa,' pl. xix. Owen, 'Anatomy of Vertebrates,' vol. iii. p. 624.) From +these various facts we may infer as probable that horns of all kinds, even +when they are equally developed in the two sexes, were primarily acquired +by the male in order to conquer other males, and have been transferred more +or less completely to the female. + +The effects of castration deserve notice, as throwing light on this same +point. Stags after the operation never renew their horns. The male +reindeer, however, must be excepted, as after castration he does renew +them. This fact, as well as the possession of horns by both sexes, seems +at first to prove that the horns in this species do not constitute a sexual +character (17. This is the conclusion of Seidlitz, 'Die Darwinsche +Theorie,' 1871, p. 47.); but as they are developed at a very early age, +before the sexes differ in constitution, it is not surprising that they +should be unaffected by castration, even if they were aboriginally acquired +by the male. With sheep both sexes properly bear horns; and I am informed +that with Welch sheep the horns of the males are considerably reduced by +castration; but the degree depends much on the age at which the operation +is performed, as is likewise the case with other animals. Merino rams have +large horns, whilst the ewes "generally speaking are without horns"; and in +this breed castration seems to produce a somewhat greater effect, so that +if performed at an early age the horns "remain almost undeveloped." (18. +I am much obliged to Prof. Victor Carus, for having made enquiries for me +in Saxony on this subject. H. von Nathusius ('Viehzucht,' 1872, p. 64) +says that the horns of sheep castrated at an early period, either +altogether disappear or remain as mere rudiments; but I do not know whether +he refers to merinos or to ordinary breeds.) On the Guinea coast there is +a breed in which the females never bear horns, and, as Mr. Winwood Reade +informs me, the rams after castration are quite destitute of them. With +cattle, the horns of the males are much altered by castration; for instead +of being short and thick, they become longer than those of the cow, but +otherwise resemble them. The Antilope bezoartica offers a somewhat +analogous case: the males have long straight spiral horns, nearly parallel +to each other, and directed backwards; the females occasionally bear horns, +but these when present are of a very different shape, for they are not +spiral, and spreading widely, bend round with the points forwards. Now it +is a remarkable fact that, in the castrated male, as Mr. Blyth informs me, +the horns are of the same peculiar shape as in the female, but longer and +thicker. If we may judge from analogy, the female probably shews us, in +these two cases of cattle and the antelope, the former condition of the +horns in some early progenitor of each species. But why castration should +lead to the reappearance of an early condition of the horns cannot be +explained with any certainty. Nevertheless, it seems probable, that in +nearly the same manner as the constitutional disturbance in the offspring, +caused by a cross between two distinct species or races, often leads to the +reappearance of long-lost characters (19. I have given various experiments +and other evidence proving that this is the case, in my 'Variation of +Animals and Plants under Domestication,' vol. ii. 1868, pp. 39-47.); so +here, the disturbance in the constitution of the individual, resulting from +castration, produces the same effect. + +The tusks of the elephant, in the different species or races, differ +according to sex, nearly as do the horns of ruminants. In India and +Malacca the males alone are provided with well-developed tusks. The +elephant of Ceylon is considered by most naturalists as a distinct race, +but by some as a distinct species, and here "not one in a hundred is found +with tusks, the few that possess them being exclusively males." (20. Sir +J. Emerson Tennent, 'Ceylon,' 1859, vol. ii. p. 274. For Malacca, 'Journal +of Indian Archipelago,' vol. iv. p. 357.) The African elephant is +undoubtedly distinct, and the female has large well-developed tusks, though +not so large as those of the male. + +These differences in the tusks of the several races and species of +elephants--the great variability of the horns of deer, as notably in the +wild reindeer--the occasional presence of horns in the female Antilope +Bezoartica, and their frequent absence in the female of Antilocapra +americana--the presence of two tusks in some few male narwhals--the +complete absence of tusks in some female walruses--are all instances of the +extreme variability of secondary sexual characters, and of their liability +to differ in closely-allied forms. + +Although tusks and horns appear in all cases to have been primarily +developed as sexual weapons, they often serve other purposes. The elephant +uses his tusks in attacking the tiger; according to Bruce, he scores the +trunks of trees until they can be thrown down easily, and he likewise thus +extracts the farinaceous cores of palms; in Africa he often uses one tusk, +always the same, to probe the ground and thus ascertain whether it will +bear his weight. The common bull defends the herd with his horns; and the +elk in Sweden has been known, according to Lloyd, to strike a wolf dead +with a single blow of his great horns. Many similar facts could be given. +One of the most curious secondary uses to which the horns of an animal may +be occasionally put is that observed by Captain Hutton (21. 'Calcutta +Journal of Natural History,' vol. ii, 1843, p. 526.) with the wild goat +(Capra aegagrus) of the Himalayas and, as it is also said with the ibex, +namely that when the male accidentally falls from a height he bends inwards +his head, and by alighting on his massive horns, breaks the shock. The +female cannot thus use her horns, which are smaller, but from her more +quiet disposition she does not need this strange kind of shield so much. + +Each male animal uses his weapons in his own peculiar fashion. The common +ram makes a charge and butts with such force with the bases of his horns, +that I have seen a powerful man knocked over like a child. Goats and +certain species of sheep, for instance the Ovis cycloceros of Afghanistan +(22. Mr. Blyth, in 'Land and Water,' March, 1867, p. 134, on the authority +of Capt. Hutton and others. For the wild Pembrokeshire goats, see the +'Field,' 1869, p. 150.), rear on their hind legs, and then not only butt, +but "make a cut down and a jerk up, with the ribbed front of their +scimitar-shaped horn, as with a sabre. When the O. cycloceros attacked a +large domestic ram, who was a noted bruiser, he conquered him by the sheer +novelty of his mode of fighting, always closing at once with his adversary, +and catching him across the face and nose with a sharp drawing jerk of the +head, and then bounding out of the way before the blow could be returned." +In Pembrokeshire a male goat, the master of a flock which during several +generations had run wild, was known to have killed several males in single +combat; this goat possessed enormous horns, measuring thirty-nine inches in +a straight line from tip to tip. The common bull, as every one knows, +gores and tosses his opponent; but the Italian buffalo is said never to use +his horns: he gives a tremendous blow with his convex forehead, and then +tramples on his fallen enemy with his knees--an instinct which the common +bull does not possess. (23. M. E.M. Bailly, "Sur l'usage des cornes," +etc., .Annal des Sciences Nat.' tom. ii. 1824, p. 369.) Hence a dog who +pins a buffalo by the nose is immediately crushed. We must, however, +remember that the Italian buffalo has been long domesticated, and it is by +no means certain that the wild parent-form had similar horns. Mr. Bartlett +informs me that when a female Cape buffalo (Bubalus caffer) was turned into +an enclosure with a bull of the same species, she attacked him, and he in +return pushed her about with great violence. But it was manifest to Mr. +Bartlett that, had not the bull shewn dignified forbearance, he could +easily have killed her by a single lateral thrust with his immense horns. +The giraffe uses his short, hair-covered horns, which are rather longer in +the male than in the female, in a curious manner; for, with his long neck, +he swings his head to either side, almost upside down, with such force that +I have seen a hard plank deeply indented by a single blow. + +[Fig. 63. Oryx leucoryx, male (from the Knowsley Menagerie).] + +With antelopes it is sometimes difficult to imagine how they can possibly +use their curiously-shaped horns; thus the springboc (Ant. euchore) has +rather short upright horns, with the sharp points bent inwards almost at +right angles, so as to face each other; Mr. Bartlett does not know how they +are used, but suggests that they would inflict a fearful wound down each +side of the face of an antagonist. The slightly-curved horns of the Oryx +leucoryx (Fig. 63) are directed backwards, and are of such length that +their points reach beyond the middle of the back, over which they extend in +almost parallel lines. Thus they seem singularly ill-fitted for fighting; +but Mr. Bartlett informs me that when two of these animals prepare for +battle, they kneel down, with their beads between their fore legs, and in +this attitude the horns stand nearly parallel and close to the ground, with +the points directed forwards and a little upwards. The combatants then +gradually approach each other, and each endeavours to get the upturned +points under the body of the other; if one succeeds in doing this, he +suddenly springs up, throwing up his head at the same time, and can thus +wound or perhaps even transfix his antagonist. Both animals always kneel +down, so as to guard as far as possible against this manoeuvre. It has +been recorded that one of these antelopes has used his horn with effect +even against a lion; yet from being forced to place his head between the +forelegs in order to bring the points of the horns forward, he would +generally be under a great disadvantage when attacked by any other animal. +It is, therefore, not probable that the horns have been modified into their +present great length and peculiar position, as a protection against beasts +of prey. We can however see that, as soon as some ancient male progenitor +of the Oryx acquired moderately long horns, directed a little backwards, he +would be compelled, in his battles with rival males, to bend his head +somewhat inwards or downwards, as is now done by certain stags; and it is +not improbable that he might have acquired the habit of at first +occasionally and afterwards of regularly kneeling down. In this case it is +almost certain that the males which possessed the longest horns would have +had a great advantage over others with shorter horns; and then the horns +would gradually have been rendered longer and longer, through sexual +selection, until they acquired their present extraordinary length and +position. + +With stags of many kinds the branches of the horns offer a curious case of +difficulty; for certainly a single straight point would inflict a much more +serious wound than several diverging ones. In Sir Philip Egerton's museum +there is a horn of the red-deer (Cervus elaphus), thirty inches in length, +with "not fewer than fifteen snags or branches"; and at Moritzburg there is +still preserved a pair of antlers of a red-deer, shot in 1699 by Frederick +I., one of which bears the astonishing number of thirty-three branches and +the other twenty-seven, making altogether sixty branches. Richardson +figures a pair of antlers of the wild reindeer with twenty-nine points. +(24. On the horns of red-deer, Owen, 'British Fossil Mammals,' 1846, p. +478; Richardson on the horns of the reindeer, 'Fauna Bor. Americana,' 1829, +p. 240. I am indebted to Prof. Victor Carus, for the Moritzburg case.) +From the manner in which the horns are branched, and more especially from +deer being known occasionally to fight together by kicking with their fore- +feet (25. Hon. J.D. Caton ('Ottawa Acad. of Nat. Science,' May 1868, p. 9) +says that the American deer fight with their fore-feet, after "the question +of superiority has been once settled and acknowledged in the herd." +Bailly, 'Sur l'Usage des cornes,' 'Annales des Sciences Nat.' tom. ii. +1824, p. 371.), M. Bailly actually comes to the conclusion that their horns +are more injurious than useful to them. But this author overlooks the +pitched battles between rival males. As I felt much perplexed about the +use or advantage of the branches, I applied to Mr. McNeill of Colonsay, who +has long and carefully observed the habits of red-deer, and he informs me +that he has never seen some of the branches brought into use, but that the +brow antlers, from inclining downwards, are a great protection to the +forehead, and their points are likewise used in attack. Sir Philip Egerton +also informs me both as to red-deer and fallow-deer that, in fighting, they +suddenly dash together, and getting their horns fixed against each other's +bodies, a desperate struggle ensues. When one is at last forced to yield +and turn round, the victor endeavours to plunge his brow antlers into his +defeated foe. It thus appears that the upper branches are used chiefly or +exclusively for pushing and fencing. Nevertheless in some species the +upper branches are used as weapons of offence; when a man was attacked by a +wapiti deer (Cervus canadensis) in Judge Caton's park in Ottawa, and +several men tried to rescue him, the stag "never raised his head from the +ground; in fact he kept his face almost flat on the ground, with his nose +nearly between his fore feet, except when he rolled his head to one side to +take a new observation preparatory to a plunge." In this position the ends +of the horns were directed against his adversaries. "In rolling his head +he necessarily raised it somewhat, because his antlers were so long that he +could not roll his head without raising them on one side, while, on the +other side they touched the ground." The stag by this procedure gradually +drove the party of rescuers backwards to a distance of 150 or 200 feet; and +the attacked man was killed. (26. See a most interesting account in the +Appendix to Hon. J.D. Caton's paper, as above quoted.) + +[Fig. 64. Strepsiceros Kudu (from Sir Andrew Smith's 'Zoology of South +Africa.'] + +Although the horns of stags are efficient weapons, there can, I think be no +doubt that a single point would have been much more dangerous than a +branched antler; and Judge Caton, who has had large experience with deer, +fully concurs in this conclusion. Nor do the branching horns, though +highly important as a means of defence against rival stags, appear +perfectly well adapted for this purpose, as they are liable to become +interlocked. The suspicion has therefore crossed my mind that they may +serve in part as ornaments. That the branched antlers of stags as well as +the elegant lyrated horns of certain antelopes, with their graceful double +curvature (Fig. 64), are ornamental in our eyes, no one will dispute. If, +then, the horns, like the splendid accoutrements of the knights of old, add +to the noble appearance of stags and antelopes, they may have been modified +partly for this purpose, though mainly for actual service in battle; but I +have no evidence in favour of this belief. + +An interesting case has lately been published, from which it appears that +the horns of a deer in one district in the United States are now being +modified through sexual and natural selection. A writer in an excellent +American Journal (27. The 'American Naturalist,' Dec. 1869, p. 552.) says, +that he has hunted for the last twenty-one years in the Adirondacks, where +the Cervus virginianus abounds. About fourteen years ago he first heard of +SPIKE-HORN BUCKS. These became from year to year more common; about five +years ago he shot one, and afterwards another, and now they are frequently +killed. "The spike-horn differs greatly from the common antler of the C. +virginianus. It consists of a single spike, more slender than the antler, +and scarcely half so long, projecting forward from the brow, and +terminating in a very sharp point. It gives a considerable advantage to +its possessor over the common buck. Besides enabling him to run more +swiftly through the thick woods and underbrush (every hunter knows that +does and yearling bucks run much more rapidly than the large bucks when +armed with their cumbrous antlers), the spike-horn is a more effective +weapon than the common antler. With this advantage the spike-horn bucks +are gaining upon the common bucks, and may, in time, entirely supersede +them in the Adirondacks. Undoubtedly, the first spike-horn buck was merely +an accidental freak of nature. But his spike-horns gave him an advantage, +and enabled him to propagate his peculiarity. His descendants having a +like advantage, have propagated the peculiarity in a constantly increasing +ratio, till they are slowly crowding the antlered deer from the region they +inhabit." A critic has well objected to this account by asking, why, if +the simple horns are now so advantageous, were the branched antlers of the +parent-form ever developed? To this I can only answer by remarking, that a +new mode of attack with new weapons might be a great advantage, as shewn by +the case of the Ovis cycloceros, who thus conquered a domestic ram famous +for his fighting power. Though the branched antlers of a stag are well +adapted for fighting with his rivals, and though it might be an advantage +to the prong-horned variety slowly to acquire long and branched horns, if +he had to fight only with others of the same kind, yet it by no means +follows that branched horns would be the best fitted for conquering a foe +differently armed. In the foregoing case of the Oryx leucoryx, it is +almost certain that the victory would rest with an antelope having short +horns, and who therefore did not need to kneel down, though an oryx might +profit by having still longer horns, if he fought only with his proper +rivals. + +Male quadrupeds, which are furnished with tusks, use them in various ways, +as in the case of horns. The boar strikes laterally and upwards; the musk- +deer downwards with serious effect. (28. Pallas, 'Spicilegia Zoologica,' +fasc. xiii. 1779, p. 18.) The walrus, though having so short a neck and so +unwieldy a body, "can strike either upwards, or downwards, or sideways, +with equal dexterity." (29. Lamont, 'Seasons with the Sea-Horses,' 1861, +p. 141.) I was informed by the late Dr. Falconer, that the Indian elephant +fights in a different manner according to the position and curvature of his +tusks. When they are directed forwards and upwards he is able to fling a +tiger to a great distance--it is said to even thirty feet; when they are +short and turned downwards he endeavours suddenly to pin the tiger to the +ground and, in consequence, is dangerous to the rider, who is liable to be +jerked off the howdah. (30. See also Corse ('Philosophical Transactions,' +1799, p. 212) on the manner in which the short-tusked Mooknah variety +attacks other elephants.) + +Very few male quadrupeds possess weapons of two distinct kinds specially +adapted for fighting with rival males. The male muntjac-deer (Cervulus), +however, offers an exception, as he is provided with horns and exserted +canine teeth. But we may infer from what follows that one form of weapon +has often been replaced in the course of ages by another. With ruminants +the development of horns generally stands in an inverse relation with that +of even moderately developed canine teeth. Thus camels, guanacoes, +chevrotains, and musk-deer, are hornless, and they have efficient canines; +these teeth being "always of smaller size in the females than in the +males." The Camelidae have, in addition to their true canines, a pair of +canine-shaped incisors in their upper jaws. (31. Owen, 'Anatomy of +Vertebrates,' vol. iii. p. 349.) Male deer and antelopes, on the other +hand, possess horns, and they rarely have canine teeth; and these, when +present, are always of small size, so that it is doubtful whether they are +of any service in their battles. In Antilope montana they exist only as +rudiments in the young male, disappearing as he grows old; and they are +absent in the female at all ages; but the females of certain other +antelopes and of certain deer have been known occasionally to exhibit +rudiments of these teeth. (32. See Ruppell (in 'Proc. Zoolog. Soc.' Jan. +12, 1836, p. 3) on the canines in deer and antelopes, with a note by Mr. +Martin on a female American deer. See also Falconer ('Palaeont. Memoirs +and Notes,' vol. i. 1868, p. 576) on canines in an adult female deer. In +old males of the musk-deer the canines (Pallas, 'Spic. Zoolog.' fasc. xiii. +1779, p. 18) sometimes grow to the length of three inches, whilst in old +females a rudiment projects scarcely half an inch above the gums.) +Stallions have small canine teeth, which are either quite absent or +rudimentary in the mare; but they do not appear to be used in fighting, for +stallions bite with their incisors, and do not open their mouths wide like +camels and guanacoes. Whenever the adult male possesses canines, now +inefficient, whilst the female has either none or mere rudiments, we may +conclude that the early male progenitor of the species was provided with +efficient canines, which have been partially transferred to the females. +The reduction of these teeth in the males seems to have followed from some +change in their manner of fighting, often (but not in the horse) caused by +the development of new weapons. + +Tusks and horns are manifestly of high importance to their possessors, for +their development consumes much organised matter. A single tusk of the +Asiatic elephant--one of the extinct woolly species--and of the African +elephant, have been known to weigh respectively 150, 160, and 180 pounds; +and even greater weights have been given by some authors. (33. Emerson +Tennent, 'Ceylon,' 1859, vol. ii. p. 275; Owen, 'British Fossil Mammals,' +1846, p. 245.) With deer, in which the horns are periodically renewed, the +drain on the constitution must be greater; the horns, for instance, of the +moose weigh from fifty to sixty pounds, and those of the extinct Irish elk +from sixty to seventy pounds--the skull of the latter weighing on an +average only five pounds and a quarter. Although the horns are not +periodically renewed in sheep, yet their development, in the opinion of +many agriculturists, entails a sensible loss to the breeder. Stags, +moreover, in escaping from beasts of prey are loaded with an additional +weight for the race, and are greatly retarded in passing through a woody +country. The moose, for instance, with horns extending five and a half +feet from tip to tip, although so skilful in their use that he will not +touch or break a twig when walking quietly, cannot act so dexterously +whilst rushing away from a pack of wolves. "During his progress he holds +his nose up, so as to lay the horns horizontally back; and in this attitude +cannot see the ground distinctly." (34. Richardson, 'Fauna Bor. +Americana,' on the moose, Alces palmata, pp. 236, 237; on the expanse of +the horns, 'Land and Water,' 1869, p. 143. See also Owen, 'British Fossil +Mammals,' on the Irish elk, pp. 447, 455.) The tips of the horns of the +great Irish elk were actually eight feet apart! Whilst the horns are +covered with velvet, which lasts with red-deer for about twelve weeks, they +are extremely sensitive to a blow; so that in Germany the stags at this +time somewhat change their habits, and avoiding dense forests, frequent +young woods and low thickets. (35. 'Forest Creatures,' by C. Boner, 1861, +p. 60.) These facts remind us that male birds have acquired ornamental +plumes at the cost of retarded flight, and other ornaments at the cost of +some loss of power in their battles with rival males. + +With mammals, when, as is often the case, the sexes differ in size, the +males are almost always larger and stronger. I am informed by Mr. Gould +that this holds good in a marked manner with the marsupials of Australia, +the males of which appear to continue growing until an unusually late age. +But the most extraordinary case is that of one of the seals (Callorhinus +ursinus), a full-grown female weighing less than one-sixth of a full-grown +male. (36. See the very interesting paper by Mr. J.A. Allen in 'Bull. +Mus. Comp. Zoology of Cambridge, United States,' vol. ii. No. 1, p. 82. +The weights were ascertained by a careful observer, Capt. Bryant. Dr. Gill +in 'The American Naturalist,' January, 1871, Prof. Shaler on the relative +size of the sexes of whales, 'American Naturalist,' January, 1873.) Dr. +Gill remarks that it is with the polygamous seals, the males of which are +well known to fight savagely together, that the sexes differ much in size; +the monogamous species differing but little. Whales also afford evidence +of the relation existing between the pugnacity of the males and their large +size compared with that of the female; the males of the right-whales do not +fight together, and they are not larger, but rather smaller, than their +females; on the other hand, male sperm-whales fight much together, and +their bodies are "often found scarred with the imprint of their rival's +teeth," and they are double the size of the females. The greater strength +of the male, as Hunter long ago remarked (37. 'Animal Economy,' p. 45.), +is invariably displayed in those parts of the body which are brought into +action in fighting with rival males--for instance, in the massive neck of +the bull. Male quadrupeds are also more courageous and pugnacious than the +females. There can be little doubt that these characters have been gained, +partly through sexual selection, owing to a long series of victories, by +the stronger and more courageous males over the weaker, and partly through +the inherited effects of use. It is probable that the successive +variations in strength, size, and courage, whether due to mere variability +or to the effects of use, by the accumulation of which male quadrupeds have +acquired these characteristic qualities, occurred rather late in life, and +were consequently to a large extent limited in their transmission to the +same sex. + +From these considerations I was anxious to obtain information as to the +Scotch deer-hound, the sexes of which differ more in size than those of any +other breed (though blood-hounds differ considerably), or than in any wild +canine species known to me. Accordingly, I applied to Mr. Cupples, well +known for his success with this breed, who has weighed and measured many of +his own dogs, and who has with great kindness collected for me the +following facts from various sources. Fine male dogs, measured at the +shoulder, range from 28 inches, which is low, to 33 or even 34 inches in +height; and in weight from 80 pounds, which is light, to 120 pounds, or +even more. The females range in height from 23 to 27, or even to 28 +inches; and in weight from 50 to 70, or even 80 pounds. (38. See also +Richardson's 'Manual on the Dog,' p. 59. Much valuable information on the +Scottish deer-hound is given by Mr. McNeill, who first called attention to +the inequality in size between the sexes, in Scrope's 'Art of Deer- +Stalking.' I hope that Mr. Cupples will keep to his intention of +publishing a full account and history of this famous breed.) Mr. Cupples +concludes that from 95 to 100 pounds for the male, and 70 for the female, +would be a safe average; but there is reason to believe that formerly both +sexes attained a greater weight. Mr. Cupples has weighed puppies when a +fortnight old; in one litter the average weight of four males exceeded that +of two females by six and a half ounces; in another litter the average +weight of four males exceeded that of one female by less than one ounce; +the same males when three weeks old, exceeded the female by seven and a +half ounces, and at the age of six weeks by nearly fourteen ounces. Mr. +Wright of Yeldersley House, in a letter to Mr. Cupples, says: "I have +taken notes on the sizes and weights of puppies of many litters, and as far +as my experience goes, dog-puppies as a rule differ very little from +bitches till they arrive at about five or six months old; and then the dogs +begin to increase, gaining upon the bitches both in weight and size. At +birth, and for several weeks afterwards, a bitch-puppy will occasionally be +larger than any of the dogs, but they are invariably beaten by them later." +Mr. McNeill, of Colonsay, concludes that "the males do not attain their +full growth till over two years old, though the females attain it sooner." +According to Mr. Cupples' experience, male dogs go on growing in stature +till they are from twelve to eighteen months old, and in weight till from +eighteen to twenty-four months old; whilst the females cease increasing in +stature at the age of from nine to fourteen or fifteen months, and in +weight at the age of from twelve to fifteen months. From these various +statements it is clear that the full difference in size between the male +and female Scotch deer-hound is not acquired until rather late in life. +The males almost exclusively are used for coursing, for, as Mr. McNeill +informs me, the females have not sufficient strength and weight to pull +down a full-grown deer. From the names used in old legends, it appears, as +I hear from Mr. Cupples, that, at a very ancient period, the males were the +most celebrated, the females being mentioned only as the mothers of famous +dogs. Hence, during many generations, it is the male which has been +chiefly tested for strength, size, speed, and courage, and the best will +have been bred from. As, however, the males do not attain their full +dimensions until rather late in life, they will have tended, in accordance +with the law often indicated, to transmit their characters to their male +offspring alone; and thus the great inequality in size between the sexes of +the Scotch deer-hound may probably be accounted for. + +[Fig. 65. Head of Common wild boar, in prime of life (from Brehm).] + +The males of some few quadrupeds possess organs or parts developed solely +as a means of defence against the attacks of other males. Some kinds of +deer use, as we have seen, the upper branches of their horns chiefly or +exclusively for defending themselves; and the Oryx antelope, as I am +informed by Mr. Bartlett, fences most skilfully with his long, gently +curved horns; but these are likewise used as organs of offence. The same +observer remarks that rhinoceroses in fighting, parry each other's sidelong +blows with their horns, which clatter loudly together, as do the tusks of +boars. Although wild boars fight desperately, they seldom, according to +Brehm, receive fatal wounds, as the blows fall on each other's tusks, or on +the layer of gristly skin covering the shoulder, called by the German +hunters, the shield; and here we have a part specially modified for +defence. With boars in the prime of life (Fig. 65) the tusks in the lower +jaw are used for fighting, but they become in old age, as Brehm states, so +much curved inwards and upwards over the snout that they can no longer be +used in this way. They may, however, still serve, and even more +effectively, as a means of defence. In compensation for the loss of the +lower tusks as weapons of offence, those in the upper jaw, which always +project a little laterally, increase in old age so much in length and curve +so much upwards that they can be used for attack. Nevertheless, an old +boar is not so dangerous to man as one at the age of six or seven years. +(39. Brehm, 'Thierleben,' B. ii. ss. 729-732.) + +[Fig. 66. Skull of the Babirusa Pig (from Wallace's 'Malay Archipelago').] + +In the full-grown male Babirusa pig of Celebes (Fig. 66), the lower tusks +are formidable weapons, like those of the European boar in the prime of +life, whilst the upper tusks are so long and have their points so much +curled inwards, sometimes even touching the forehead, that they are utterly +useless as weapons of attack. They more nearly resemble horns than teeth, +and are so manifestly useless as teeth that the animal was formerly +supposed to rest his head by hooking them on to a branch! Their convex +surfaces, however, if the head were held a little laterally, would serve as +an excellent guard; and hence, perhaps, it is that in old animals they "are +generally broken off, as if by fighting." (40. See Mr. Wallace's +interesting account of this animal, 'The Malay Archipelago,' 1869, vol. i. +p. 435.) Here, then, we have the curious case of the upper tusks of the +Babirusa regularly assuming during the prime of life a structure which +apparently renders them fitted only for defence; whilst in the European +boar the lower tusks assume in a less degree and only during old age nearly +the same form, and then serve in like manner solely for defence. + +[Fig. 67. Head of female Aethopian wart-hog, from 'Proc. Zool. Soc.' 1869, +shewing the same characters as the male, though on a reduced scale. +N.B. When the engraving was first made, I was under the impression that it +represented the male.] + +In the wart-hog (see Phacochoerus aethiopicus, Fig. 67) the tusks in the +upper jaw of the male curve upwards during the prime of life, and from +being pointed serve as formidable weapons. The tusks in the lower jaw are +sharper than those in the upper, but from their shortness it seems hardly +possible that they can be used as weapons of attack. They must, however, +greatly strengthen those in the upper jaw, from being ground so as to fit +closely against their bases. Neither the upper nor the lower tusks appear +to have been specially modified to act as guards, though no doubt they are +to a certain extent used for this purpose. But the wart-hog is not +destitute of other special means of protection, for it has, on each side of +the face, beneath the eyes, a rather stiff, yet flexible, cartilaginous, +oblong pad (Fig. 67), which projects two or three inches outwards; and it +appeared to Mr. Bartlett and myself, when viewing the living animal, that +these pads, when struck from beneath by the tusks of an opponent, would be +turned upwards, and would thus admirably protect the somewhat prominent +eyes. I may add, on the authority of Mr. Bartlett, that these boars when +fighting stand directly face to face. + +Lastly, the African river-hog (Potomochoerus penicillatus) has a hard +cartilaginous knob on each side of the face beneath the eyes, which answers +to the flexible pad of the wart-hog; it has also two bony prominences on +the upper jaw above the nostrils. A boar of this species in the Zoological +Gardens recently broke into the cage of the wart-hog. They fought all +night long, and were found in the morning much exhausted, but not seriously +wounded. It is a significant fact, as shewing the purposes of the above- +described projections and excrescences, that these were covered with blood, +and were scored and abraded in an extraordinary manner. + +Although the males of so many members of the pig family are provided with +weapons, and as we have just seen with means of defence, these weapons seem +to have been acquired within a rather late geological period. Dr. Forsyth +Major specifies (41. 'Atti della Soc. Italiana di Sc. Nat.' 1873, vol. xv. +fasc. iv.) several miocene species, in none of which do the tusks appear to +have been largely developed in the males; and Professor Rutimeyer was +formerly struck with this same fact. + +The mane of the lion forms a good defence against the attacks of rival +lions, the one danger to which he is liable; for the males, as Sir A. Smith +informs me, engage in terrible battles, and a young lion dares not approach +an old one. In 1857 a tiger at Bromwich broke into the cage of a lion and +a fearful scene ensued: "the lion's mane saved his neck and head from +being much injured, but the tiger at last succeeded in ripping up his +belly, and in a few minutes he was dead." (42. 'The Times,' Nov. 10, +1857. In regard to the Canada lynx, see Audubon and Bachman, 'Quadrupeds +of North America,' 1846, p. 139.) The broad ruff round the throat and chin +of the Canadian lynx (Felis canadensis) is much longer in the male than in +the female; but whether it serves as a defence I do not know. Male seals +are well known to fight desperately together, and the males of certain +kinds (Otaria jubata) (43. Dr. Murie, on Otaria, 'Proc. Zoolog. Soc.' +1869, p. 109. Mr. J.A. Allen, in the paper above quoted (p. 75), doubts +whether the hair, which is longer on the neck in the male than in the +female, deserves to be called a mane.) have great manes, whilst the females +have small ones or none. The male baboon of the Cape of Good Hope +(Cynocephalus porcarius) has a much longer mane and larger canine teeth +than the female; and the mane probably serves as a protection, for, on +asking the keepers in the Zoological Gardens, without giving them any clue +to my object, whether any of the monkeys especially attacked each other by +the nape of the neck, I was answered that this was not the case, except +with the above baboon. In the Hamadryas baboon, Ehrenberg compares the +mane of the adult male to that of a young lion, whilst in the young of both +sexes and in the female the mane is almost absent. + +It appeared to me probable that the immense woolly mane of the male +American bison, which reaches almost to the ground, and is much more +developed in the males than in the females, served as a protection to them +in their terrible battles; but an experienced hunter told Judge Caton that +he had never observed anything which favoured this belief. The stallion +has a thicker and fuller mane than the mare; and I have made particular +inquiries of two great trainers and breeders, who have had charge of many +entire horses, and am assured that they "invariably endeavour to seize one +another by the neck." It does not, however, follow from the foregoing +statements, that when the hair on the neck serves as a defence, that it was +originally developed for this purpose, though this is probable in some +cases, as in that of the lion. I am informed by Mr. McNeill that the long +hairs on the throat of the stag (Cervus elaphus) serve as a great +protection to him when hunted, for the dogs generally endeavour to seize +him by the throat; but it is not probable that these hairs were specially +developed for this purpose; otherwise the young and the females would have +been equally protected. + +CHOICE IN PAIRING BY EITHER SEX OF QUADRUPEDS. + +Before describing in the next chapter, the differences between the sexes in +voice, odours emitted, and ornaments, it will be convenient here to +consider whether the sexes exert any choice in their unions. Does the +female prefer any particular male, either before or after the males may +have fought together for supremacy; or does the male, when not a +polygamist, select any particular female? The general impression amongst +breeders seems to be that the male accepts any female; and this owing to +his eagerness, is, in most cases, probably the truth. Whether the female +as a general rule indifferently accepts any male is much more doubtful. In +the fourteenth chapter, on Birds, a considerable body of direct and +indirect evidence was advanced, shewing that the female selects her +partner; and it would be a strange anomaly if female quadrupeds, which +stand higher in the scale and have higher mental powers, did not generally, +or at least often, exert some choice. The female could in most cases +escape, if wooed by a male that did not please or excite her; and when +pursued by several males, as commonly occurs, she would often have the +opportunity, whilst they were fighting together, of escaping with some one +male, or at least of temporarily pairing with him. This latter contingency +has often been observed in Scotland with female red-deer, as I am informed +by Sir Philip Egerton and others. (44. Mr. Boner, in his excellent +description of the habits of the red-deer in Germany ('Forest Creatures,' +1861, p. 81) says, "while the stag is defending his rights against one +intruder, another invades the sanctuary of his harem, and carries off +trophy after trophy." Exactly the same thing occurs with seals; see Mr. +J.A. Allen, ibid. p. 100.) + +It is scarcely possible that much should be known about female quadrupeds +in a state of nature making any choice in their marriage unions. The +following curious details on the courtship of one of the eared seals +(Callorhinus ursinus) are given (45. Mr. J.A. Allen in 'Bull. Mus. Comp. +Zoolog. of Cambridge, United States,' vol. ii. No. 1, p. 99.) on the +authority of Capt. Bryant, who had ample opportunities for observation. He +says, "Many of the females on their arrival at the island where they breed +appear desirous of returning to some particular male, and frequently climb +the outlying rocks to overlook the rookeries, calling out and listening as +if for a familiar voice. Then changing to another place they do the same +again...As soon as a female reaches the shore, the nearest male goes down +to meet her, making meanwhile a noise like the clucking of a hen to her +chickens. He bows to her and coaxes her until he gets between her and the +water so that she cannot escape him. Then his manner changes, and with a +harsh growl he drives her to a place in his harem. This continues until +the lower row of harems is nearly full. Then the males higher up select +the time when their more fortunate neighbours are off their guard to steal +their wives. This they do by taking them in their mouths and lifting them +over the heads of the other females, and carefully placing them in their +own harem, carrying them as cats do their kittens. Those still higher up +pursue the same method until the whole space is occupied. Frequently a +struggle ensues between two males for the possession of the same female, +and both seizing her at once pull her in two or terribly lacerate her with +their teeth. When the space is all filled, the old male walks around +complacently reviewing his family, scolding those who crowd or disturb the +others, and fiercely driving off all intruders. This surveillance always +keeps him actively occupied." + +As so little is known about the courtship of animals in a state of nature, +I have endeavoured to discover how far our domesticated quadrupeds evince +any choice in their unions. Dogs offer the best opportunity for +observation, as they are carefully attended to and well understood. Many +breeders have expressed a strong opinion on this head. Thus, Mr. Mayhew +remarks, "The females are able to bestow their affections; and tender +recollections are as potent over them as they are known to be in other +cases, where higher animals are concerned. Bitches are not always prudent +in their loves, but are apt to fling themselves away on curs of low degree. +If reared with a companion of vulgar appearance, there often springs up +between the pair a devotion which no time can afterwards subdue. The +passion, for such it really is, becomes of a more than romantic endurance." +Mr. Mayhew, who attended chiefly to the smaller breeds, is convinced that +the females are strongly attracted by males of a large size. (46. 'Dogs: +their Management,' by E. Mayhew, M.R.C.V.S., 2nd ed., 1864, pp. 187-192.) +The well-known veterinary Blaine states (47. Quoted by Alex. Walker, 'On +Intermarriage,' 1838, p. 276; see also p. 244.) that his own female pug dog +became so attached to a spaniel, and a female setter to a cur, that in +neither case would they pair with a dog of their own breed until several +weeks had elapsed. Two similar and trustworthy accounts have been given me +in regard to a female retriever and a spaniel, both of which became +enamoured with terrier-dogs. + +Mr. Cupples informs me that he can personally vouch for the accuracy of the +following more remarkable case, in which a valuable and wonderfully- +intelligent female terrier loved a retriever belonging to a neighbour to +such a degree, that she had often to be dragged away from him. After their +permanent separation, although repeatedly shewing milk in her teats, she +would never acknowledge the courtship of any other dog, and to the regret +of her owner never bore puppies. Mr. Cupples also states, that in 1868, a +female deerhound in his kennel thrice produced puppies, and on each +occasion shewed a marked preference for one of the largest and handsomest, +but not the most eager, of four deerhounds living with her, all in the +prime of life. Mr. Cupples has observed that the female generally favours a +dog whom she has associated with and knows; her shyness and timidity at +first incline her against a strange dog. The male, on the contrary, seems +rather inclined towards strange females. It appears to be rare when the +male refuses any particular female, but Mr. Wright, of Yeldersley House, a +great breeder of dogs, informs me that he has known some instances; he +cites the case of one of his own deerhounds, who would not take any notice +of a particular female mastiff, so that another deerhound had to be +employed. It would be superfluous to give, as I could, other instances, +and I will only add that Mr. Barr, who has carefully bred many bloodhounds, +states that in almost every instance particular individuals of opposite +sexes shew a decided preference for each other. Finally, Mr. Cupples, +after attending to this subject for another year, has written to me, "I +have had full confirmation of my former statement, that dogs in breeding +form decided preferences for each other, being often influenced by size, +bright colour, and individual characters, as well as by the degree of their +previous familiarity." + +In regard to horses, Mr. Blenkiron, the greatest breeder of race-horses in +the world, informs me that stallions are so frequently capricious in their +choice, rejecting one mare and without any apparent cause taking to +another, that various artifices have to be habitually used. The famous +Monarque, for instance, would never consciously look at the dam of +Gladiateur, and a trick had to be practised. We can partly see the reason +why valuable race-horse stallions, which are in such demand as to be +exhausted, should be so particular in their choice. Mr. Blenkiron has +never known a mare reject a horse; but this has occurred in Mr. Wright's +stable, so that the mare had to be cheated. Prosper Lucas (48. 'Traité de +l'Héréd. Nat.' tom. ii. 1850, p. 296.) quotes various statements from +French authorities, and remarks, "On voit des étalons qui s'eprennent d'une +jument, et negligent toutes les autres." He gives, on the authority of +Baelen, similar facts in regard to bulls; and Mr. H. Reeks assures me that +a famous short-horn bull belonging to his father "invariably refused to be +matched with a black cow." Hoffberg, in describing the domesticated +reindeer of Lapland says, "Foeminae majores et fortiores mares prae +caeteris admittunt, ad eos confugiunt, a junioribus agitatae, qui hos in +fugam conjiciunt." (49. 'Amoenitates Acad.' vol. iv. 1788, p. 160.) A +clergyman, who has bred many pigs, asserts that sows often reject one boar +and immediately accept another. + +From these facts there can be no doubt that, with most of our domesticated +quadrupeds, strong individual antipathies and preferences are frequently +exhibited, and much more commonly by the female than by the male. This +being the case, it is improbable that the unions of quadrupeds in a state +of nature should be left to mere chance. It is much more probable that the +females are allured or excited by particular males, who possess certain +characters in a higher degree than other males; but what these characters +are, we can seldom or never discover with certainty. + + +CHAPTER XVIII. + +SECONDARY SEXUAL CHARACTERS OF MAMMALS--continued. + +Voice--Remarkable sexual peculiarities in seals--Odour--Development of the +hair--Colour of the hair and skin--Anomalous case of the female being more +ornamented than the male--Colour and ornaments due to sexual selection-- +Colour acquired for the sake of protection--Colour, though common to both +sexes, often due to sexual selection--On the disappearance of spots and +stripes in adult quadrupeds--On the colours and ornaments of the +Quadrumana--Summary. + +Quadrupeds use their voices for various purposes, as a signal of danger, as +a call from one member of a troop to another, or from the mother to her +lost offspring, or from the latter for protection to their mother; but such +uses need not here be considered. We are concerned only with the +difference between the voices of the sexes, for instance between that of +the lion and lioness, or of the bull and cow. Almost all male animals use +their voices much more during the rutting-season than at any other time; +and some, as the giraffe and porcupine (1. Owen, 'Anatomy of Vertebrates,' +vol. iii. p. 585.), are said to be completely mute excepting at this +season. As the throats (i.e. the larynx and thyroid bodies (2. Ibid. p. +595.)) of stags periodically become enlarged at the beginning of the +breeding-season, it might be thought that their powerful voices must be +somehow of high importance to them; but this is very doubtful. From +information given to me by two experienced observers, Mr. McNeill and Sir +P. Egerton, it seems that young stags under three years old do not roar or +bellow; and that the old ones begin bellowing at the commencement of the +breeding-season, at first only occasionally and moderately, whilst they +restlessly wander about in search of the females. Their battles are +prefaced by loud and prolonged bellowing, but during the actual conflict +they are silent. Animals of all kinds which habitually use their voices +utter various noises under any strong emotion, as when enraged and +preparing to fight; but this may merely be the result of nervous +excitement, which leads to the spasmodic contraction of almost all the +muscles of the body, as when a man grinds his teeth and clenches his fists +in rage or agony. No doubt stags challenge each other to mortal combat by +bellowing; but those with the more powerful voices, unless at the same time +the stronger, better-armed, and more courageous, would not gain any +advantage over their rivals. + +It is possible that the roaring of the lion may be of some service to him +by striking terror into his adversary; for when enraged he likewise erects +his mane and thus instinctively tries to make himself appear as terrible as +possible. But it can hardly be supposed that the bellowing of the stag, +even if it be of service to him in this way, can have been important enough +to have led to the periodical enlargement of the throat. Some writers +suggest that the bellowing serves as a call to the female; but the +experienced observers above quoted inform me that female deer do not search +for the male, though the males search eagerly for the females, as indeed +might be expected from what we know of the habits of other male quadrupeds. +The voice of the female, on the other hand, quickly brings to her one or +more stags (3. See, for instance, Major W. Ross King ('The Sportsman in +Canada,' 1866, pp. 53, 131) on the habits of the moose and wild reindeer.), +as is well known to the hunters who in wild countries imitate her cry. If +we could believe that the male had the power to excite or allure the female +by his voice, the periodical enlargement of his vocal organs would be +intelligible on the principle of sexual selection, together with +inheritance limited to the same sex and season; but we have no evidence in +favour of this view. As the case stands, the loud voice of the stag during +the breeding-season does not seem to be of any special service to him, +either during his courtship or battles, or in any other way. But may we +not believe that the frequent use of the voice, under the strong excitement +of love, jealousy, and rage, continued during many generations, may at last +have produced an inherited effect on the vocal organs of the stag, as well +as of other male animals? This appears to me, in our present state of +knowledge, the most probable view. + +The voice of the adult male gorilla is tremendous, and he is furnished with +a laryngeal sack, as is the adult male orang. (4. Owen 'Anatomy of +Vertebrates,' vol. iii. p. 600.) The gibbons rank among the noisiest of +monkeys, and the Sumatra species (Hylobates syndactylus) is also furnished +with an air sack; but Mr. Blyth, who has had opportunities for observation, +does not believe that the male is noisier than the female. Hence, these +latter monkeys probably use their voices as a mutual call; and this is +certainly the case with some quadrupeds, for instance the beaver. (5. Mr. +Green, in 'Journal of Linnean Society,' vol. x. 'Zoology,' 1869, note 362.) +Another gibbon, the H. agilis, is remarkable, from having the power of +giving a complete and correct octave of musical notes (6. C.L. Martin, +'General Introduction to the Natural History of Mamm. Animals,' 1841, p. +431.), which we may reasonably suspect serves as a sexual charm; but I +shall have to recur to this subject in the next chapter. The vocal organs +of the American Mycetes caraya are one-third larger in the male than in the +female, and are wonderfully powerful. These monkeys in warm weather make +the forests resound at morning and evening with their overwhelming voices. +The males begin the dreadful concert, and often continue it during many +hours, the females sometimes joining in with their less powerful voices. +An excellent observer, Rengger (7. 'Naturgeschichte der Säugethiere von +Paraguay,' 1830, ss. 15, 21.), could not perceive that they were excited to +begin by any special cause; he thinks that, like many birds, they delight +in their own music, and try to excel each other. Whether most of the +foregoing monkeys have acquired their powerful voices in order to beat +their rivals and charm the females--or whether the vocal organs have been +strengthened and enlarged through the inherited effects of long-continued +use without any particular good being thus gained--I will not pretend to +say; but the former view, at least in the case of the Hylobates agilis, +seems the most probable. + +I may here mention two very curious sexual peculiarities occurring in +seals, because they have been supposed by some writers to affect the voice. +The nose of the male sea-elephant (Macrorhinus proboscideus) becomes +greatly elongated during the breeding-season, and can then be erected. In +this state it is sometimes a foot in length. The female is not thus +provided at any period of life. The male makes a wild, hoarse, gurgling +noise, which is audible at a great distance and is believed to be +strengthened by the proboscis; the voice of the female being different. +Lesson compares the erection of the proboscis, with the swelling of the +wattles of male gallinaceous birds whilst courting the females. In another +allied kind of seal, the bladder-nose (Cystophora cristata), the head is +covered by a great hood or bladder. This is supported by the septum of the +nose, which is produced far backwards and rises into an internal crest +seven inches in height. The hood is clothed with short hair, and is +muscular; can be inflated until it more than equals the whole head in size! +The males when rutting, fight furiously on the ice, and their roaring "is +said to be sometimes so loud as to be heard four miles off." When attacked +they likewise roar or bellow; and whenever irritated the bladder is +inflated and quivers. Some naturalists believe that the voice is thus +strengthened, but various other uses have been assigned to this +extraordinary structure. Mr. R. Brown thinks that it serves as a +protection against accidents of all kinds; but this is not probable, for, +as I am assured by Mr. Lamont who killed 600 of these animals, the hood is +rudimentary in the females, and it is not developed in the males during +youth. (8. On the sea-elephant, see an article by Lesson, in 'Dict. +Class. Hist. Nat.' tom. xiii. p. 418. For the Cystophora, or Stemmatopus, +see Dr. Dekay, 'Annals of Lyceum of Nat. Hist.' New York, vol. i. 1824, p. +94. Pennant has also collected information from the sealers on this +animal. The fullest account is given by Mr. Brown, in 'Proc. Zoolog. Soc.' +1868, p. 435.) + +ODOUR. + +With some animals, as with the notorious skunk of America, the overwhelming +odour which they emit appears to serve exclusively as a defence. With +shrew-mice (Sorex) both sexes possess abdominal scent-glands, and there can +be little doubt, from the rejection of their bodies by birds and beasts of +prey, that the odour is protective; nevertheless, the glands become +enlarged in the males during the breeding-season. In many other quadrupeds +the glands are of the same size in both sexes (9. As with the castoreum of +the beaver, see Mr. L.H. Morgan's most interesting work, 'The American +Beaver,' 1868, p. 300. Pallas ('Spic. Zoolog.' fasc. viii. 1779, p. 23) +has well discussed the odoriferous glands of mammals. Owen ('Anat. of +Vertebrates,' vol. iii. p. 634) also gives an account of these glands, +including those of the elephant, and (p. 763) those of shrew-mice. On +bats, Mr. Dobson in 'Proceedings of the Zoological Society' 1873, p. 241.), +but their uses are not known. In other species the glands are confined to +the males, or are more developed than in the females; and they almost +always become more active during the rutting-season. At this period the +glands on the sides of the face of the male elephant enlarge, and emit a +secretion having a strong musky odour. The males, and rarely the females, +of many kinds of bats have glands and protrudable sacks situated in various +parts; and it is believed that these are odoriferous. + +The rank effluvium of the male goat is well known, and that of certain male +deer is wonderfully strong and persistent. On the banks of the Plata I +perceived the air tainted with the odour of the male Cervus campestris, at +half a mile to leeward of a herd; and a silk handkerchief, in which I +carried home a skin, though often used and washed, retained, when first +unfolded, traces of the odour for one year and seven months. This animal +does not emit its strong odour until more than a year old, and if castrated +whilst young never emits it. (10. Rengger, 'Naturgeschichte der +Säugethiere von Paraguay,' 1830, s. 355. This observer also gives some +curious particulars in regard to the odour.) Besides the general odour, +permeating the whole body of certain ruminants (for instance, Bos +moschatus) in the breeding-season, many deer, antelopes, sheep, and goats +possess odoriferous glands in various situations, more especially on their +faces. The so-called tear-sacks, or suborbital pits, come under this head. +These glands secrete a semi-fluid fetid matter which is sometimes so +copious as to stain the whole face, as I have myself seen in an antelope. +They are "usually larger in the male than in the female, and their +development is checked by castration." (11. Owen, 'Anatomy of +Vertebrates,' vol. iii. p. 632. See also Dr. Murie's observations on those +glands in the 'Proc. Zoolog. Soc.' 1870, p. 340. Desmarest, 'On the +Antilope subgutturosa, 'Mammalogie,' 1820, p. 455.) According to Desmarest +they are altogether absent in the female of Antilope subgutturosa. Hence, +there can be no doubt that they stand in close relation with the +reproductive functions. They are also sometimes present, and sometimes +absent, in nearly allied forms. In the adult male musk-deer (Moschus +moschiferus), a naked space round the tail is bedewed with an odoriferous +fluid, whilst in the adult female, and in the male until two years old, +this space is covered with hair and is not odoriferous. The proper musk- +sack of this deer is from its position necessarily confined to the male, +and forms an additional scent-organ. It is a singular fact that the matter +secreted by this latter gland, does not, according to Pallas, change in +consistence, or increase in quantity, during the rutting-season; +nevertheless this naturalist admits that its presence is in some way +connected with the act of reproduction. He gives, however, only a +conjectural and unsatisfactory explanation of its use. (12. Pallas, +'Spicilegia Zoolog.' fasc. xiii. 1799, p. 24; Desmoulins, 'Dict. Class. +d'Hist. Nat.' tom. iii. p. 586.) + +In most cases, when only the male emits a strong odour during the breeding- +season, it probably serves to excite or allure the female. We must not +judge on this head by our own taste, for it is well known that rats are +enticed by certain essential oils, and cats by valerian, substances far +from agreeable to us; and that dogs, though they will not eat carrion, +sniff and roll on it. From the reasons given when discussing the voice of +the stag, we may reject the idea that the odour serves to bring the females +from a distance to the males. Active and long-continued use cannot here +have come into play, as in the case of the vocal organs. The odour emitted +must be of considerable importance to the male, inasmuch as large and +complex glands, furnished with muscles for everting the sack, and for +closing or opening the orifice, have in some cases been developed. The +development of these organs is intelligible through sexual selection, if +the most odoriferous males are the most successful in winning the females, +and in leaving offspring to inherit their gradually perfected glands and +odours. + +DEVELOPMENT OF THE HAIR. + +We have seen that male quadrupeds often have the hair on their necks and +shoulders much more developed than the females; and many additional +instances could be given. This sometimes serves as a defence to the male +during his battles; but whether the hair in most cases has been specially +developed for this purpose, is very doubtful. We may feel almost certain +that this is not the case, when only a thin and narrow crest runs along the +back; for a crest of this kind would afford scarcely any protection, and +the ridge of the back is not a place likely to be injured; nevertheless +such crests are sometimes confined to the males, or are much more developed +in them than in the females. Two antelopes, the Tragelaphus scriptus (13. +Dr. Gray, 'Gleanings from the Menagerie at Knowsley,' pl. 28.) (Fig. 70) +and Portax picta may be given as instances. When stags, and the males of +the wild goat, are enraged or terrified, these crests stand erect (14. +Judge Caton on the Wapiti, 'Transact. Ottawa Acad. Nat. Sciences,' 1868, +pp. 36, 40; Blyth, 'Land and Water,' on Capra aegagrus 1867, p. 37.); but +it cannot be supposed that they have been developed merely for the sake of +exciting fear in their enemies. One of the above-named antelopes, the +Portax picta, has a large well-defined brush of black hair on the throat, +and this is much larger in the male than in the female. In the Ammotragus +tragelaphus of North Africa, a member of the sheep-family, the fore-legs +are almost concealed by an extraordinary growth of hair, which depends from +the neck and upper halves of the legs; but Mr. Bartlett does not believe +that this mantle is of the least use to the male, in whom it is much more +developed than in the female. + +[Fig. 68. Pithecia satanas, male (from Brehm).] + +Male quadrupeds of many kinds differ from the females in having more hair, +or hair of a different character, on certain parts of their faces. Thus +the bull alone has curled hair on the forehead. (15. Hunter's 'Essays and +Observations,' edited by Owen, 1861. vol. i. p. 236.) In three closely- +allied sub-genera of the goat family, only the males possess beards, +sometimes of large size; in two other sub-genera both sexes have a beard, +but it disappears in some of the domestic breeds of the common goat; and +neither sex of the Hemitragus has a beard. In the ibex the beard is not +developed during the summer, and is so small at other times that it may be +called rudimentary. (16. See Dr. Gray's 'Catalogue of Mammalia in the +British Museum,' part iii. 1852, p. 144.) With some monkeys the beard is +confined to the male, as in the orang; or is much larger in the male than +in the female, as in the Mycetes caraya and Pithecia satanas (Fig. 68). So +it is with the whiskers of some species of Macacus (17. Rengger, +'Saugthiere,' etc., s. 14; Desmarest, 'Mammalogie,' p. 86.), and, as we +have seen, with the manes of some species of baboons. But with most kinds +of monkeys the various tufts of hair about the face and head are alike in +both sexes. + +The males of various members of the ox family (Bovidae), and of certain +antelopes, are furnished with a dewlap, or great fold of skin on the neck, +which is much less developed in the female. + +Now, what must we conclude with respect to such sexual differences as +these? No one will pretend that the beards of certain male goats, or the +dewlaps of the bull, or the crests of hair along the backs of certain male +antelopes, are of any use to them in their ordinary habits. It is possible +that the immense beard of the male Pithecia, and the large beard of the +male orang, may protect their throats when fighting; for the keepers in the +Zoological Gardens inform me that many monkeys attack each other by the +throat; but it is not probable that the beard has been developed for a +distinct purpose from that served by the whiskers, moustache, and other +tufts of hair on the face; and no one will suppose that these are useful as +a protection. Must we attribute all these appendages of hair or skin to +mere purposeless variability in the male? It cannot be denied that this is +possible; for in many domesticated quadrupeds, certain characters, +apparently not derived through reversion from any wild parent form, are +confined to the males, or are more developed in them than in the females-- +for instance, the hump on the male zebu-cattle of India, the tail of fat- +tailed rams, the arched outline of the forehead in the males of several +breeds of sheep, and lastly, the mane, the long hairs on the hind legs, and +the dewlap of the male of the Berbura goat. (18. See the chapters on +these several animals in vol. i. of my 'Variation of Animals under +Domestication;' also vol. ii. p. 73; also chap. xx. on the practice of +selection by semi-civilised people. For the Berbura goat, see Dr. Gray, +'Catalogue,' ibid. p. 157.) The mane, which occurs only in the rams of an +African breed of sheep, is a true secondary sexual character, for, as I +hear from Mr. Winwood Reade, it is not developed if the animal be +castrated. Although we ought to be extremely cautious, as shewn in my work +on 'Variation under Domestication,' in concluding that any character, even +with animals kept by semi-civilised people, has not been subjected to +selection by man, and thus augmented, yet in the cases just specified this +is improbable; more especially as the characters are confined to the males, +or are more strongly developed in them than in the females. If it were +positively known that the above African ram is a descendant of the same +primitive stock as the other breeds of sheep, and if the Berbura male-goat +with his mane, dewlap, etc., is descended from the same stock as other +goats, then, assuming that selection has not been applied to these +characters, they must be due to simple variability, together with sexually- +limited inheritance. + +Hence it appears reasonable to extend this same view to all analogous cases +with animals in a state of nature. Nevertheless I cannot persuade myself +that it generally holds good, as in the case of the extraordinary +development of hair on the throat and fore-legs of the male Ammotragus, or +in that of the immense beard of the male Pithecia. Such study as I have +been able to give to nature makes me believe that parts or organs which are +highly developed, were acquired at some period for a special purpose. With +those antelopes in which the adult male is more strongly-coloured than the +female, and with those monkeys in which the hair on the face is elegantly +arranged and coloured in a diversified manner, it seems probable that the +crests and tufts of hair were gained as ornaments; and this I know is the +opinion of some naturalists. If this be correct, there can be little doubt +that they were gained or at least modified through sexual selection; but +how far the same view may be extended to other mammals is doubtful. + +COLOUR OF THE HAIR AND OF THE NAKED SKIN. + +I will first give briefly all the cases known to me of male quadrupeds +differing in colour from the females. With Marsupials, as I am informed by +Mr. Gould, the sexes rarely differ in this respect; but the great red +kangaroo offers a striking exception, "delicate blue being the prevailing +tint in those parts of the female which in the male are red." (19. +Osphranter rufus, Gould, 'Mammals of Australia,' 1863, vol. ii. On the +Didelphis, Desmarest, 'Mammalogie,' p. 256.) In the Didelphis opossum of +Cayenne the female is said to be a little more red than the male. Of the +Rodents, Dr. Gray remarks: "African squirrels, especially those found in +the tropical regions, have the fur much brighter and more vivid at some +seasons of the year than at others, and the fur of the male is generally +brighter than that of the female." (20. 'Annals and Magazine of Natural +History,' Nov. 1867, p. 325. On the Mus minutus, Desmarest, 'Mammalogie,' +p. 304.) Dr. Gray informs me that he specified the African squirrels, +because, from their unusually bright colours, they best exhibit this +difference. The female of the Mus minutus of Russia is of a paler and +dirtier tint than the male. In a large number of bats the fur of the male +is lighter than in the female. (21. J.A. Allen, in 'Bulletin of Mus. +Comp. Zoolog. of Cambridge, United States,' 1869, p. 207. Mr. Dobson on +sexual characters in the Chiroptera, 'Proceedings of the Zoological +Society,' 1873, p. 241. Dr. Gray on Sloths, ibid. 1871, p. 436.) Mr. +Dobson also remarks, with respect to these animals: "Differences, +depending partly or entirely on the possession by the male of fur of a much +more brilliant hue, or distinguished by different markings or by the +greater length of certain portions, are met only, to any appreciable +extent, in the frugivorous bats in which the sense of sight is well +developed." This last remark deserves attention, as bearing on the +question whether bright colours are serviceable to male animals from being +ornamental. In one genus of sloths, it is now established, as Dr. Gray +states, "that the males are ornamented differently from the females--that +is to say, that they have a patch of soft short hair between the shoulders, +which is generally of a more or less orange colour, and in one species pure +white. The females, on the contrary, are destitute of this mark." + +The terrestrial Carnivora and Insectivora rarely exhibit sexual differences +of any kind, including colour. The ocelot (Felis pardalis), however, is +exceptional, for the colours of the female, compared with those of the +male, are "moins apparentes, le fauve, étant plus terne, le blanc moins +pur, les raies ayant moins de largeur et les taches moins de diamètre." +(22. Desmarest, 'Mammalogie,' 1820, p. 220. On Felis mitis, Rengger, +ibid. s. 194.) The sexes of the allied Felis mitis also differ, but in a +less degree; the general hues of the female being rather paler than in the +male, with the spots less black. The marine Carnivora or seals, on the +other hand, sometimes differ considerably in colour, and they present, as +we have already seen, other remarkable sexual differences. Thus the male +of the Otaria nigrescens of the southern hemisphere is of a rich brown +shade above; whilst the female, who acquires her adult tints earlier in +life than the male, is dark-grey above, the young of both sexes being of a +deep chocolate colour. The male of the northern Phoca groenlandica is +tawny grey, with a curious saddle-shaped dark mark on the back; the female +is much smaller, and has a very different appearance, being "dull white or +yellowish straw-colour, with a tawny hue on the back"; the young at first +are pure white, and can "hardly be distinguished among the icy hummocks and +snow, their colour thus acting as a protection." (23. Dr. Murie on the +Otaria, 'Proceedings Zoological Society,' 1869, p. 108. Mr. R. Brown on +the P. groenlandica, ibid. 1868, p. 417. See also on the colours of seals, +Desmarest, ibid. pp. 243, 249.) + +With Ruminants sexual differences of colour occur more commonly than in any +other order. A difference of this kind is general in the Strepsicerene +antelopes; thus the male nilghau (Portax picta) is bluish-grey and much +darker than the female, with the square white patch on the throat, the +white marks on the fetlocks, and the black spots on the ears all much more +distinct. We have seen that in this species the crests and tufts of hair +are likewise more developed in the male than in the hornless female. I am +informed by Mr. Blyth that the male, without shedding his hair, +periodically becomes darker during the breeding-season. Young males cannot +be distinguished from young females until about twelve months old; and if +the male is emasculated before this period, he never, according to the same +authority, changes colour. The importance of this latter fact, as evidence +that the colouring of the Portax is of sexual origin, becomes obvious, when +we hear (24. Judge Caton, in 'Transactions of the Ottawa Academy of +Natural Sciences,' 1868, p. 4.) that neither the red summer-coat nor the +blue winter-coat of the Virginian deer is at all affected by emasculation. +With most or all of the highly-ornamented species of Tragelaphus the males +are darker than the hornless females, and their crests of hair are more +fully developed. In the male of that magnificent antelope, the Derbyan +eland, the body is redder, the whole neck much blacker, and the white band +which separates these colours broader than in the female. In the Cape +eland, also, the male is slightly darker than the female. (25. Dr. Gray, +'Cat. of Mamm. in Brit. Mus.' part iii. 1852, pp. 134-142; also Dr. Gray, +'Gleanings from the Menagerie of Knowsley,' in which there is a splendid +drawing of the Oreas derbianus: see the text on Tragelaphus. For the Cape +eland (Oreas canna), see Andrew Smith, 'Zoology of S. Africa,' pl. 41 and +42. There are also many of these Antelopes in the Zoological Gardens.) + +In the Indian black-buck (A. bezoartica), which belongs to another tribe of +antelopes, the male is very dark, almost black; whilst the hornless female +is fawn-coloured. We meet in this species, as Mr. Blyth informs me, with +an exactly similar series of facts, as in the Portax picta, namely, in the +male periodically changing colour during the breeding-season, in the +effects of emasculation on this change, and in the young of both sexes +being indistinguishable from each other. In the Antilope niger the male is +black, the female, as well as the young of both sexes, being brown; in A. +sing-sing the male is much brighter coloured than the hornless female, and +his chest and belly are blacker; in the male A. caama, the marks and lines +which occur on various parts of the body are black, instead of brown as in +the female; in the brindled gnu (A. gorgon) "the colours of the male are +nearly the same as those of the female, only deeper and of a brighter hue." +(26. On the Ant. niger, see 'Proc. Zool. Soc.' 1850, p. 133. With respect +to an allied species, in which there is an equal sexual difference in +colour, see Sir S. Baker, 'The Albert Nyanza,' 1866, vol. ii. p. 627. For +the A. sing-sing, Gray, 'Cat. B. Mus.' p. 100. Desmarest, 'Mammalogie,' p. +468, on the A. caama. Andrew Smith, 'Zoology of S. Africa,' on the Gnu.) +Other analogous cases could be added. + +The Banteng bull (Bos sondaicus) of the Malayan Archipelago is almost +black, with white legs and buttocks; the cow is of a bright dun, as are the +young males until about the age of three years, when they rapidly change +colour. The emasculated bull reverts to the colour of the female. The +female Kemas goat is paler, and both it and the female Capra aegagrus are +said to be more uniformly tinted than their males. Deer rarely present any +sexual differences in colour. Judge Caton, however, informs me that in the +males of the wapiti deer (Cervus canadensis) the neck, belly, and legs are +much darker than in the female; but during the winter the darker tints +gradually fade away and disappear. I may here mention that Judge Caton has +in his park three races of the Virginian deer, which differ slightly in +colour, but the differences are almost exclusively confined to the blue +winter or breeding-coat; so that this case may be compared with those given +in a previous chapter of closely-allied or representative species of birds, +which differ from each other only in their breeding plumage. (27. 'Ottawa +Academy of Sciences,' May 21, 1868, pp. 3, 5.) The females of Cervus +paludosus of S. America, as well as the young of both sexes, do not possess +the black stripes on the nose and the blackish-brown line on the breast, +which are characteristic of the adult males. (28. S. Muller, on the +Banteng, 'Zoog. Indischen Archipel.' 1839-1844, tab. 35; see also Raffles, +as quoted by Mr. Blyth, in 'Land and Water,' 1867, p. 476. On goats, Dr. +Gray, 'Catalogue of the British Museum,' p. 146; Desmarest, 'Mammalogie,' +p. 482. On the Cervus paludosus, Rengger, ibid. s. 345.) Lastly, as I am +informed by Mr. Blyth, the mature male of the beautifully coloured and +spotted axis deer is considerably darker than the female: and this hue the +castrated male never acquires. + +The last Order which we need consider is that of the Primates. The male of +the Lemur macaco is generally coal-black, whilst the female is brown. (29. +Sclater, 'Proc. Zool. Soc.' 1866, p. i. The same fact has also been fully +ascertained by MM. Pollen and van Dam. See, also, Dr. Gray in 'Annals and +Magazine of Natural History,' May 1871, p. 340.) Of the Quadrumana of the +New World, the females and young of Mycetes caraya are greyish-yellow and +like each other; in the second year the young male becomes reddish-brown; +in the third, black, excepting the stomach, which, however, becomes quite +black in the fourth or fifth year. There is also a strongly-marked +difference in colour between the sexes of Mycetes seniculus and Cebus +capucinus; the young of the former, and I believe of the latter species, +resembling the females. With Pithecia leucocephala the young likewise +resemble the females, which are brownish-black above and light rusty-red +beneath, the adult males being black. The ruff of hair round the face of +Ateles marginatus is tinted yellow in the male and white in the female. +Turning to the Old World, the males of Hylobates hoolock are always black, +with the exception of a white band over the brows; the females vary from +whity-brown to a dark tint mixed with black, but are never wholly black. +(30. On Mycetes, Rengger, ibid. s. 14; and Brehm, 'Thierleben,' B. i. s. +96, 107. On Ateles Desmarest, 'Mammalogie,' p. 75. On Hylobates, Blyth, +'Land and Water,' 1867, p. 135. On the Semnopithecus, S. Muller, 'Zoog. +Indischen Archipel.' tab. x.) In the beautiful Cercopithecus diana, the +head of the adult male is of an intense black, whilst that of the female is +dark grey; in the former the fur between the thighs is of an elegant fawn- +colour, in the latter it is paler. In the beautiful and curious moustache +monkey (Cercopithecus cephus) the only difference between the sexes is that +the tail of the male is chestnut and that of the female grey; but Mr. +Bartlett informs me that all the hues become more pronounced in the male +when adult, whilst in the female they remain as they were during youth. +According to the coloured figures given by Solomon Muller, the male of +Semnopithecus chrysomelas is nearly black, the female being pale brown. In +the Cercopithecus cynosurus and griseo-viridis one part of the body, which +is confined to the male sex, is of the most brilliant blue or green, and +contrasts strikingly with the naked skin on the hinder part of the body, +which is vivid red. + +[Fig. 69. Head of male Mandrill (from Gervais, 'Hist. Nat. des +Mammifères').] + +Lastly, in the baboon family, the adult male of Cynocephalus hamadryas +differs from the female not only by his immense mane, but slightly in the +colour of the hair and of the naked callosities. In the drill (C. +leucophaeus) the females and young are much paler-coloured, with less +green, than the adult males. No other member in the whole class of mammals +is coloured in so extraordinary a manner as the adult male mandrill (C. +mormon). The face at this age becomes of a fine blue, with the ridge and +tip of the nose of the most brilliant red. According to some authors, the +face is also marked with whitish stripes, and is shaded in parts with +black, but the colours appear to be variable. On the forehead there is a +crest of hair, and on the chin a yellow beard. "Toutes les parties +supérieures de leurs cuisses et le grand espace nu de leurs fesses sont +également colorés du rouge le plus vif, avec un mélange de bleu qui ne +manque reellement pas d'élégance." (31. Gervais, 'Hist. Nat. des +Mammifères,' 1854, p. 103. Figures are given of the skull of the male. +Also Desmarest, 'Mammalogie,' p. 70. Geoffroy St.-Hilaire and F. Cuvier, +'Hist. Nat. des Mammifères,' 1824, tom. i.) When the animal is excited all +the naked parts become much more vividly tinted. Several authors have used +the strongest expressions in describing these resplendent colours, which +they compare with those of the most brilliant birds. Another remarkable +peculiarity is that when the great canine teeth are fully developed, +immense protuberances of bone are formed on each cheek, which are deeply +furrowed longitudinally, and the naked skin over them is brilliantly- +coloured, as just-described. (Fig. 69.) In the adult females and in the +young of both sexes these protuberances are scarcely perceptible; and the +naked parts are much less bright coloured, the face being almost black, +tinged with blue. In the adult female, however, the nose at certain +regular intervals of time becomes tinted with red. + +In all the cases hitherto given the male is more strongly or brighter +coloured than the female, and differs from the young of both sexes. But as +with some few birds it is the female which is brighter coloured than the +male, so with the Rhesus monkey (Macacus rhesus), the female has a large +surface of naked skin round the tail, of a brilliant carmine red, which, as +I was assured by the keepers in the Zoological Gardens, periodically +becomes even yet more vivid, and her face also is pale red. On the other +hand, in the adult male and in the young of both sexes (as I saw in the +Gardens), neither the naked skin at the posterior end of the body, nor the +face, shew a trace of red. It appears, however, from some published +accounts, that the male does occasionally, or during certain seasons, +exhibit some traces of the red. Although he is thus less ornamented than +the female, yet in the larger size of his body larger canine teeth, more +developed whiskers, more prominent superciliary ridges, he follows the +common rule of the male excelling the female. + +I have now given all the cases known to me of a difference in colour +between the sexes of mammals. Some of these may be the result of +variations confined to one sex and transmitted to the same sex, without any +good being gained, and therefore without the aid of selection. We have +instances of this with our domesticated animals, as in the males of certain +cats being rusty-red, whilst the females are tortoise-shell coloured. +Analogous cases occur in nature: Mr. Bartlett has seen many black +varieties of the jaguar, leopard, vulpine phalanger, and wombat; and he is +certain that all, or nearly all these animals, were males. On the other +hand, with wolves, foxes, and apparently American squirrels, both sexes are +occasionally born black. Hence it is quite possible that with some mammals +a difference in colour between the sexes, especially when this is +congenital, may simply be the result, without the aid of selection, of the +occurrence of one or more variations, which from the first were sexually +limited in their transmission. Nevertheless it is improbable that the +diversified, vivid, and contrasted colours of certain quadrupeds, for +instance, of the above monkeys and antelopes, can thus be accounted for. +We should bear in mind that these colours do not appear in the male at +birth, but only at or near maturity; and that unlike ordinary variations, +they are lost if the male be emasculated. It is on the whole probable that +the strongly-marked colours and other ornamental characters of male +quadrupeds are beneficial to them in their rivalry with other males, and +have consequently been acquired through sexual selection. This view is +strengthened by the differences in colour between the sexes occurring +almost exclusively, as may be collected from the previous details, in those +groups and sub-groups of mammals which present other and strongly-marked +secondary sexual characters; these being likewise due to sexual selection. + +Quadrupeds manifestly take notice of colour. Sir S. Baker repeatedly +observed that the African elephant and rhinoceros attacked white or grey +horses with special fury. I have elsewhere shewn (32. The 'Variation of +Animals and Plants under Domestication,' 1868, vol. ii. pp. 102, 103.) that +half-wild horses apparently prefer to pair with those of the same colour, +and that herds of fallow-deer of different colours, though living together, +have long kept distinct. It is a more significant fact that a female zebra +would not admit the addresses of a male ass until he was painted so as to +resemble a zebra, and then, as John Hunter remarks, "she received him very +readily. In this curious fact, we have instinct excited by mere colour, +which had so strong an effect as to get the better of everything else. But +the male did not require this, the female being an animal somewhat similar +to himself, was sufficient to rouse him." (33. 'Essays and Observations,' +by J. Hunter, edited by Owen, 1861, vol. i. p. 194.) + +In an earlier chapter we have seen that the mental powers of the higher +animals do not differ in kind, though greatly in degree, from the +corresponding powers of man, especially of the lower and barbarous races; +and it would appear that even their taste for the beautiful is not widely +different from that of the Quadrumana. As the negro of Africa raises the +flesh on his face into parallel ridges "or cicatrices, high above the +natural surface, which unsightly deformities are considered great personal +attractions" (34. Sir S. Baker, 'The Nile Tributaries of Abyssinia,' +1867.);--as negroes and savages in many parts of the world paint their +faces with red, blue, white, or black bars,--so the male mandrill of Africa +appears to have acquired his deeply-furrowed and gaudily-coloured face from +having been thus rendered attractive to the female. No doubt it is to us a +most grotesque notion that the posterior end of the body should be coloured +for the sake of ornament even more brilliantly than the face; but this is +not more strange than that the tails of many birds should be especially +decorated. + +With mammals we do not at present possess any evidence that the males take +pains to display their charms before the female; and the elaborate manner +in which this is performed by male birds and other animals is the strongest +argument in favour of the belief that the females admire, or are excited +by, the ornaments and colours displayed before them. There is, however, a +striking parallelism between mammals and birds in all their secondary +sexual characters, namely in their weapons for fighting with rival males, +in their ornamental appendages, and in their colours. In both classes, +when the male differs from the female, the young of both sexes almost +always resemble each other, and in a large majority of cases resemble the +adult female. In both classes the male assumes the characters proper to +his sex shortly before the age of reproduction; and if emasculated at an +early period, loses them. In both classes the change of colour is +sometimes seasonal, and the tints of the naked parts sometimes become more +vivid during the act of courtship. In both classes the male is almost +always more vividly or strongly coloured than the female, and is ornamented +with larger crests of hair or feathers, or other such appendages. In a few +exceptional cases the female in both classes is more highly ornamented than +the male. With many mammals, and at least in the case of one bird, the +male is more odoriferous than the female. In both classes the voice of the +male is more powerful than that of the female. Considering this +parallelism, there can be little doubt that the same cause, whatever it may +be, has acted on mammals and birds; and the result, as far as ornamental +characters are concerned, may be attributed, as it appears to me, to the +long-continued preference of the individuals of one sex for certain +individuals of the opposite sex, combined with their success in leaving a +larger number of offspring to inherit their superior attractions. + +EQUAL TRANSMISSION OF ORNAMENTAL CHARACTERS TO BOTH SEXES. + +With many birds, ornaments, which analogy leads us to believe were +primarily acquired by the males, have been transmitted equally, or almost +equally, to both sexes; and we may now enquire how far this view applies to +mammals. With a considerable number of species, especially of the smaller +kinds, both sexes have been coloured, independently of sexual selection, +for the sake of protection; but not, as far as I can judge, in so many +cases, nor in so striking a manner, as in most of the lower classes. +Audubon remarks that he often mistook the musk-rat (35. Fiber zibethicus, +Audubon and Bachman, 'The Quadrupeds of North America,' 1846, p. 109.), +whilst sitting on the banks of a muddy stream, for a clod of earth, so +complete was the resemblance. The hare on her form is a familiar instance +of concealment through colour; yet this principle partly fails in a +closely-allied species, the rabbit, for when running to its burrow, it is +made conspicuous to the sportsman, and no doubt to all beasts of prey, by +its upturned white tail. No one doubts that the quadrupeds inhabiting +snow-clad regions have been rendered white to protect them from their +enemies, or to favour their stealing on their prey. In regions where snow +never lies for long, a white coat would be injurious; consequently, species +of this colour are extremely rare in the hotter parts of the world. It +deserves notice that many quadrupeds inhabiting moderately cold regions, +although they do not assume a white winter dress, become paler during this +season; and this apparently is the direct result of the conditions to which +they have long been exposed. Pallas (36. 'Novae species Quadrupedum e +Glirium ordine,' 1778, p. 7. What I have called the roe is the Capreolus +sibiricus subecaudatus of Pallas.) states that in Siberia a change of this +nature occurs with the wolf, two species of Mustela, the domestic horse, +the Equus hemionus, the domestic cow, two species of antelopes, the musk- +deer, the roe, elk, and reindeer. The roe, for instance, has a red summer +and a greyish-white winter coat; and the latter may perhaps serve as a +protection to the animal whilst wandering through the leafless thickets, +sprinkled with snow and hoar-frost. If the above-named animals were +gradually to extend their range into regions perpetually covered with snow, +their pale winter-coats would probably be rendered through natural +selection, whiter and whiter, until they became as white as snow. + +Mr. Reeks has given me a curious instance of an animal profiting by being +peculiarly coloured. He raised from fifty to sixty white and brown piebald +rabbits in a large walled orchard; and he had at the same time some +similarly coloured cats in his house. Such cats, as I have often noticed, +are very conspicuous during day; but as they used to lie in watch during +the dusk at the mouths of the burrows, the rabbits apparently did not +distinguish them from their parti-coloured brethren. The result was that, +within eighteen months, every one of these parti-coloured rabbits was +destroyed; and there was evidence that this was effected by the cats. +Colour seems to be advantageous to another animal, the skunk, in a manner +of which we have had many instances in other classes. No animal will +voluntarily attack one of these creatures on account of the dreadful odour +which it emits when irritated; but during the dusk it would not easily be +recognised and might be attacked by a beast of prey. Hence it is, as Mr. +Belt believes (37. 'The Naturalist in Nicaragua,' p. 249.), that the skunk +is provided with a great white bushy tail, which serves as a conspicuous +warning. + +[Fig. 70. Tragelaphus scriptus, male (from the Knowsley Menagerie). + +Fig. 71. Damalis pygarga, male (from the Knowsley Menagerie).] + +Although we must admit that many quadrupeds have received their present +tints either as a protection, or as an aid in procuring prey, yet with a +host of species, the colours are far too conspicuous and too singularly +arranged to allow us to suppose that they serve for these purposes. We may +take as an illustration certain antelopes; when we see the square white +patch on the throat, the white marks on the fetlocks, and the round black +spots on the ears, all more distinct in the male of the Portax picta, than +in the female;--when we see that the colours are more vivid, that the +narrow white lines on the flank and the broad white bar on the shoulder are +more distinct in the male Oreas derbyanus than in the female;--when we see +a similar difference between the sexes of the curiously-ornamented +Tragelaphus scriptus (Fig. 70),--we cannot believe that differences of this +kind are of any service to either sex in their daily habits of life. It +seems a much more probable conclusion that the various marks were first +acquired by the males and their colours intensified through sexual +selection, and then partially transferred to the females. If this view be +admitted, there can be little doubt that the equally singular colours and +marks of many other antelopes, though common to both sexes, have been +gained and transmitted in a like manner. Both sexes, for instance, of the +koodoo (Strepsiceros kudu) (Fig. 64) have narrow white vertical lines on +their hind flanks, and an elegant angular white mark on their foreheads. +Both sexes in the genus Damalis are very oddly coloured; in D. pygarga the +back and neck are purplish-red, shading on the flanks into black; and these +colours are abruptly separated from the white belly and from a large white +space on the buttocks; the head is still more oddly coloured, a large +oblong white mask, narrowly-edged with black, covers the face up to the +eyes (Fig. 71); there are three white stripes on the forehead, and the ears +are marked with white. The fawns of this species are of a uniform pale +yellowish-brown. In Damalis albifrons the colouring of the head differs +from that in the last species in a single white stripe replacing the three +stripes, and in the ears being almost wholly white. (38. See the fine +plates in A. Smith's 'Zoology of South Africa,' and Dr. Gray's 'Gleanings +from the Menagerie of Knowsley.') After having studied to the best of my +ability the sexual differences of animals belonging to all classes, I +cannot avoid the conclusion that the curiously-arranged colours of many +antelopes, though common to both sexes, are the result of sexual selection +primarily applied to the male. + +The same conclusion may perhaps be extended to the tiger, one of the most +beautiful animals in the world, the sexes of which cannot be distinguished +by colour, even by the dealers in wild beasts. Mr. Wallace believes (39. +'Westminster Review,' July 1, 1867, p. 5.) that the striped coat of the +tiger "so assimilates with the vertical stems of the bamboo, as to assist +greatly in concealing him from his approaching prey." But this view does +not appear to me satisfactory. We have some slight evidence that his +beauty may be due to sexual selection, for in two species of Felis the +analogous marks and colours are rather brighter in the male than in the +female. The zebra is conspicuously striped, and stripes cannot afford any +protection in the open plains of South Africa. Burchell (40. 'Travels in +South Africa,' 1824, vol. ii. p. 315.) in describing a herd says, "their +sleek ribs glistened in the sun, and the brightness and regularity of their +striped coats presented a picture of extraordinary beauty, in which +probably they are not surpassed by any other quadruped." But as throughout +the whole group of the Equidae the sexes are identical in colour, we have +here no evidence of sexual selection. Nevertheless he who attributes the +white and dark vertical stripes on the flanks of various antelopes to this +process, will probably extend the same view to the Royal Tiger and +beautiful Zebra. + +We have seen in a former chapter that when young animals belonging to any +class follow nearly the same habits of life as their parents, and yet are +coloured in a different manner, it may be inferred that they have retained +the colouring of some ancient and extinct progenitor. In the family of +pigs, and in the tapirs, the young are marked with longitudinal stripes, +and thus differ from all the existing adult species in these two groups. +With many kinds of deer the young are marked with elegant white spots, of +which their parents exhibit not a trace. A graduated series can be +followed from the axis deer, both sexes of which at all ages and during all +seasons are beautifully spotted (the male being rather more strongly +coloured than the female), to species in which neither the old nor the +young are spotted. I will specify some of the steps in this series. The +Mantchurian deer (Cervus mantchuricus) is spotted during the whole year, +but, as I have seen in the Zoological Gardens, the spots are much plainer +during the summer, when the general colour of the coat is lighter, than +during the winter, when the general colour is darker and the horns are +fully developed. In the hog-deer (Hyelaphus porcinus) the spots are +extremely conspicuous during the summer when the coat is reddish-brown, but +quite disappear during the winter when the coat is brown. (41. Dr. Gray, +'Gleanings from the Menagerie of Knowsley,' p. 64. Mr. Blyth, in speaking +('Land and Water,' 1869, p. 42) of the hog-deer of Ceylon, says it is more +brightly spotted with white than the common hog-deer, at the season when it +renews its horns.) In both these species the young are spotted. In the +Virginian deer the young are likewise spotted, and about five per cent. of +the adult animals living in Judge Caton's park, as I am informed by him, +temporarily exhibit at the period when the red summer coat is being +replaced by the bluish winter coat, a row of spots on each flank, which are +always the same in number, though very variable in distinctness. From this +condition there is but a very small step to the complete absence of spots +in the adults at all seasons; and, lastly, to their absence at all ages and +seasons, as occurs with certain species. From the existence of this +perfect series, and more especially from the fawns of so many species being +spotted, we may conclude that the now living members of the deer family are +the descendants of some ancient species which, like the axis deer, was +spotted at all ages and seasons. A still more ancient progenitor probably +somewhat resembled the Hyomoschus aquaticus--for this animal is spotted, +and the hornless males have large exserted canine teeth, of which some few +true deer still retain rudiments. Hyomoschus, also, offers one of those +interesting cases of a form linking together two groups, for it is +intermediate in certain osteological characters between the pachyderms and +ruminants, which were formerly thought to be quite distinct. (42. +Falconer and Cautley, 'Proc. Geolog. Soc.' 1843; and Falconer's 'Pal. +Memoirs,' vol. i. p. 196.) + +A curious difficulty here arises. If we admit that coloured spots and +stripes were first acquired as ornaments, how comes it that so many +existing deer, the descendants of an aboriginally spotted animal, and all +the species of pigs and tapirs, the descendants of an aboriginally striped +animal, have lost in their adult state their former ornaments? I cannot +satisfactorily answer this question. We may feel almost sure that the +spots and stripes disappeared at or near maturity in the progenitors of our +existing species, so that they were still retained by the young; and, owing +to the law of inheritance at corresponding ages, were transmitted to the +young of all succeeding generations. It may have been a great advantage to +the lion and puma, from the open nature of their usual haunts, to have lost +their stripes, and to have been thus rendered less conspicuous to their +prey; and if the successive variations, by which this end was gained, +occurred rather late in life, the young would have retained their stripes, +as is now the case. As to deer, pigs, and tapirs, Fritz Müller has +suggested to me that these animals, by the removal of their spots or +stripes through natural selection, would have been less easily seen by +their enemies; and that they would have especially required this +protection, as soon as the carnivora increased in size and number during +the tertiary periods. This may be the true explanation, but it is rather +strange that the young should not have been thus protected, and still more +so that the adults of some species should have retained their spots, either +partially or completely, during part of the year. We know that, when the +domestic ass varies and becomes reddish-brown, grey, or black, the stripes +on the shoulders and even on the spine frequently disappear, though we +cannot explain the cause. Very few horses, except dun-coloured kinds, have +stripes on any part of their bodies, yet we have good reason to believe +that the aboriginal horse was striped on the legs and spine, and probably +on the shoulders. (43. The 'Variation of Animals and Plants under +Domestication,' 1868, vol. i. pp. 61-64.) Hence the disappearance of the +spots and stripes in our adult existing deer, pigs, and tapirs, may be due +to a change in the general colour of their coats; but whether this change +was effected through sexual or natural selection, or was due to the direct +action of the conditions of life, or to some other unknown cause, it is +impossible to decide. An observation made by Mr. Sclater well illustrates +our ignorance of the laws which regulate the appearance and disappearance +of stripes; the species of Asinus which inhabit the Asiatic continent are +destitute of stripes, not having even the cross shoulder-stripe, whilst +those which inhabit Africa are conspicuously striped, with the partial +exception of A. taeniopus, which has only the cross shoulder-stripe and +generally some faint bars on the legs; and this species inhabits the almost +intermediate region of Upper Egypt and Abyssinia. (44. 'Proc. Zool. Soc.' +1862, p. 164. See, also, Dr. Hartmann, 'Ann. d. Landw.' Bd. xliii. s. +222.) + +QUADRUMANA. + +[Fig. 72. Head of Semnopithecus rubicundus. This and the following +figures (from Prof. Gervais) are given to shew the odd arrangement and +development of the hair on the head. + +Fig. 73. Head of Semnopithecus comatus. + +Fig. 74. Head of Cebus capucinus. + +Fig. 75. Head of Ateles marginatus. + +Fig. 76. Head of Cebus vellerosus.] + +Before we conclude, it will be well to add a few remarks on the ornaments +of monkeys. In most of the species the sexes resemble each other in +colour, but in some, as we have seen, the males differ from the females, +especially in the colour of the naked parts of the skin, in the development +of the beard, whiskers, and mane. Many species are coloured either in so +extraordinary or so beautiful a manner, and are furnished with such curious +and elegant crests of hair, that we can hardly avoid looking at these +characters as having been gained for the sake of ornament. The +accompanying figures (Figs. 72 to 76) serve to shew the arrangement of the +hair on the face and head in several species. It is scarcely conceivable +that these crests of hair, and the strongly contrasted colours of the fur +and skin, can be the result of mere variability without the aid of +selection; and it is inconceivable that they can be of use in any ordinary +way to these animals. If so, they have probably been gained through sexual +selection, though transmitted equally, or almost equally, to both sexes. +With many of the Quadrumana, we have additional evidence of the action of +sexual selection in the greater size and strength of the males, and in the +greater development of their canine teeth, in comparison with the females. + +[Fig. 77. Cercopithecus petaurista (from Brehm).] + +A few instances will suffice of the strange manner in which both sexes of +some species are coloured, and of the beauty of others. The face of the +Cercopithecus petaurista (Fig. 77) is black, the whiskers and beard being +white, with a defined, round, white spot on the nose, covered with short +white hair, which gives to the animal an almost ludicrous aspect. The +Semnopithecus frontatus likewise has a blackish face with a long black +beard, and a large naked spot on the forehead of a bluish-white colour. +The face of Macacus lasiotus is dirty flesh-coloured, with a defined red +spot on each cheek. The appearance of Cercocebus aethiops is grotesque, +with its black face, white whiskers and collar, chestnut head, and a large +naked white spot over each eyelid. In very many species, the beard, +whiskers, and crests of hair round the face are of a different colour from +the rest of the head, and when different, are always of a lighter tint (45. +I observed this fact in the Zoological Gardens; and many cases may be seen +in the coloured plates in Geoffroy St.-Hilaire and F. Cuvier, 'Histoire +Nat. des Mammifères,' tom. i. 1824.), being often pure white, sometimes +bright yellow, or reddish. The whole face of the South American Brachyurus +calvus is of a "glowing scarlet hue"; but this colour does not appear until +the animal is nearly mature. (46. Bates, 'The Naturalist on the Amazons,' +1863, vol. ii. p. 310.) The naked skin of the face differs wonderfully in +colour in the various species. It is often brown or flesh-colour, with +parts perfectly white, and often as black as that of the most sooty negro. +In the Brachyurus the scarlet tint is brighter than that of the most +blushing Caucasian damsel. It is sometimes more distinctly orange than in +any Mongolian, and in several species it is blue, passing into violet or +grey. In all the species known to Mr. Bartlett, in which the adults of +both sexes have strongly-coloured faces, the colours are dull or absent +during early youth. This likewise holds good with the mandrill and Rhesus, +in which the face and the posterior parts of the body are brilliantly +coloured in one sex alone. In these latter cases we have reason to believe +that the colours were acquired through sexual selection; and we are +naturally led to extend the same view to the foregoing species, though both +sexes when adult have their faces coloured in the same manner. + +[Fig. 78. Cercopithecus diana (from Brehm).] + +Although many kinds of monkeys are far from beautiful according to our +taste, other species are universally admired for their elegant appearance +and bright colours. The Semnopithecus nemaeus, though peculiarly coloured, +is described as extremely pretty; the orange-tinted face is surrounded by +long whiskers of glossy whiteness, with a line of chestnut-red over the +eyebrows; the fur on the back is of a delicate grey, with a square patch on +the loins, the tail and the fore-arms being of a pure white; a gorget of +chestnut surmounts the chest; the thighs are black, with the legs chestnut- +red. I will mention only two other monkeys for their beauty; and I have +selected these as presenting slight sexual differences in colour, which +renders it in some degree probable that both sexes owe their elegant +appearance to sexual selection. In the moustache-monkey (Cercopithecus +cephus) the general colour of the fur is mottled-greenish with the throat +white; in the male the end of the tail is chestnut, but the face is the +most ornamented part, the skin being chiefly bluish-grey, shading into a +blackish tint beneath the eyes, with the upper lip of a delicate blue, +clothed on the lower edge with a thin black moustache; the whiskers are +orange-coloured, with the upper part black, forming a band which extends +backwards to the ears, the latter being clothed with whitish hairs. In the +Zoological Society's Gardens I have often overheard visitors admiring the +beauty of another monkey, deservedly called Cercopithecus diana (Fig. 78); +the general colour of the fur is grey; the chest and inner surface of the +forelegs are white; a large triangular defined space on the hinder part of +the back is rich chestnut; in the male the inner sides of the thighs and +the abdomen are delicate fawn-coloured, and the top of the head is black; +the face and ears are intensely black, contrasting finely with a white +transverse crest over the eyebrows and a long white peaked beard, of which +the basal portion is black. (47. I have seen most of the above monkeys in +the Zoological Society's Gardens. The description of the Semnopithecus +nemaeus is taken from Mr. W.C. Martin's 'Natural History of Mammalia,' +1841, p. 460; see also pp. 475, 523.) + +In these and many other monkeys, the beauty and singular arrangement of +their colours, and still more the diversified and elegant arrangement of +the crests and tufts of hair on their heads, force the conviction on my +mind that these characters have been acquired through sexual selection +exclusively as ornaments. + +SUMMARY. + +The law of battle for the possession of the female appears to prevail +throughout the whole great class of mammals. Most naturalists will admit +that the greater size, strength, courage, and pugnacity of the male, his +special weapons of offence, as well as his special means of defence, have +been acquired or modified through that form of selection which I have +called sexual. This does not depend on any superiority in the general +struggle for life, but on certain individuals of one sex, generally the +male, being successful in conquering other males, and leaving a larger +number of offspring to inherit their superiority than do the less +successful males. + +There is another and more peaceful kind of contest, in which the males +endeavour to excite or allure the females by various charms. This is +probably carried on in some cases by the powerful odours emitted by the +males during the breeding-season; the odoriferous glands having been +acquired through sexual selection. Whether the same view can be extended +to the voice is doubtful, for the vocal organs of the males must have been +strengthened by use during maturity, under the powerful excitements of +love, jealousy or rage, and will consequently have been transmitted to the +same sex. Various crests, tufts, and mantles of hair, which are either +confined to the male, or are more developed in this sex than in the female, +seem in most cases to be merely ornamental, though they sometimes serve as +a defence against rival males. There is even reason to suspect that the +branching horns of stags, and the elegant horns of certain antelopes, +though properly serving as weapons of offence or defence, have been partly +modified for ornament. + +When the male differs in colour from the female, he generally exhibits +darker and more strongly-contrasted tints. We do not in this class meet +with the splendid red, blue, yellow, and green tints, so common with male +birds and many other animals. The naked parts, however, of certain +Quadrumana must be excepted; for such parts, often oddly situated, are +brilliantly coloured in some species. The colours of the male in other +cases may be due to simple variation, without the aid of selection. But +when the colours are diversified and strongly pronounced, when they are not +developed until near maturity, and when they are lost after emasculation, +we can hardly avoid the conclusion that they have been acquired through +sexual selection for the sake of ornament, and have been transmitted +exclusively, or almost exclusively, to the same sex. When both sexes are +coloured in the same manner, and the colours are conspicuous or curiously +arranged, without being of the least apparent use as a protection, and +especially when they are associated with various other ornamental +appendages, we are led by analogy to the same conclusion, namely, that they +have been acquired through sexual selection, although transmitted to both +sexes. That conspicuous and diversified colours, whether confined to the +males or common to both sexes, are as a general rule associated in the same +groups and sub-groups with other secondary sexual characters serving for +war or for ornament, will be found to hold good, if we look back to the +various cases given in this and the last chapter. + +The law of the equal transmission of characters to both sexes, as far as +colour and other ornaments are concerned, has prevailed far more +extensively with mammals than with birds; but weapons, such as horns and +tusks, have often been transmitted either exclusively or much more +perfectly to the males than to the females. This is surprising, for, as +the males generally use their weapons for defence against enemies of all +kinds, their weapons would have been of service to the females. As far as +we can see, their absence in this sex can be accounted for only by the form +of inheritance which has prevailed. Finally, with quadrupeds the contest +between the individuals of the same sex, whether peaceful or bloody, has, +with the rarest exceptions, been confined to the males; so that the latter +have been modified through sexual selection, far more commonly than the +females, either for fighting with each other or for alluring the opposite +sex. + + +PART III. + +SEXUAL SELECTION IN RELATION TO MAN, AND CONCLUSION. + + +CHAPTER XIX. + +SECONDARY SEXUAL CHARACTERS OF MAN. + +Differences between man and woman--Causes of such differences and of +certain characters common to both sexes--Law of battle--Differences in +mental powers, and voice--On the influence of beauty in determining the +marriages of mankind--Attention paid by savages to ornaments--Their ideas +of beauty in woman--The tendency to exaggerate each natural peculiarity. + +With mankind the differences between the sexes are greater than in most of +the Quadrumana, but not so great as in some, for instance, the mandrill. +Man on an average is considerably taller, heavier, and stronger than woman, +with squarer shoulders and more plainly-pronounced muscles. Owing to the +relation which exists between muscular development and the projection of +the brows (1. Schaaffhausen, translation in 'Anthropological Review,' Oct. +1868, pp. 419, 420, 427.), the superciliary ridge is generally more marked +in man than in woman. His body, and especially his face, is more hairy, +and his voice has a different and more powerful tone. In certain races the +women are said to differ slightly in tint from the men. For instance, +Schweinfurth, in speaking of a negress belonging to the Monbuttoos, who +inhabit the interior of Africa a few degrees north of the equator, says, +"Like all her race, she had a skin several shades lighter than her +husband's, being something of the colour of half-roasted coffee." (2. 'The +Heart of Africa,' English transl. 1873, vol i. p. 544.) As the women +labour in the fields and are quite unclothed, it is not likely that they +differ in colour from the men owing to less exposure to the weather. +European women are perhaps the brighter coloured of the two sexes, as may +be seen when both have been equally exposed. + +Man is more courageous, pugnacious and energetic than woman, and has a more +inventive genius. His brain is absolutely larger, but whether or not +proportionately to his larger body, has not, I believe, been fully +ascertained. In woman the face is rounder; the jaws and the base of the +skull smaller; the outlines of the body rounder, in parts more prominent; +and her pelvis is broader than in man (3. Ecker, translation, in +'Anthropological Review,' Oct. 1868, pp. 351-356. The comparison of the +form of the skull in men and women has been followed out with much care by +Welcker.); but this latter character may perhaps be considered rather as a +primary than a secondary sexual character. She comes to maturity at an +earlier age than man. + +As with animals of all classes, so with man, the distinctive characters of +the male sex are not fully developed until he is nearly mature; and if +emasculated they never appear. The beard, for instance, is a secondary +sexual character, and male children are beardless, though at an early age +they have abundant hair on the head. It is probably due to the rather late +appearance in life of the successive variations whereby man has acquired +his masculine characters, that they are transmitted to the male sex alone. +Male and female children resemble each other closely, like the young of so +many other animals in which the adult sexes differ widely; they likewise +resemble the mature female much more closely than the mature male. The +female, however, ultimately assumes certain distinctive characters, and in +the formation of her skull, is said to be intermediate between the child +and the man. (4. Ecker and Welcker, ibid. pp. 352, 355; Vogt, 'Lectures +on Man,' Eng. translat. p. 81.) Again, as the young of closely allied +though distinct species do not differ nearly so much from each other as do +the adults, so it is with the children of the different races of man. Some +have even maintained that race-differences cannot be detected in the +infantile skull. (5. Schaaffhausen, 'Anthropolog. Review,' ibid. p. 429.) +In regard to colour, the new-born negro child is reddish nut-brown, which +soon becomes slaty-grey; the black colour being fully developed within a +year in the Soudan, but not until three years in Egypt. The eyes of the +negro are at first blue, and the hair chestnut-brown rather than black, +being curled only at the ends. The children of the Australians immediately +after birth are yellowish-brown, and become dark at a later age. Those of +the Guaranys of Paraguay are whitish-yellow, but they acquire in the course +of a few weeks the yellowish-brown tint of their parents. Similar +observations have been made in other parts of America. (6. Pruner-Bey, on +negro infants as quoted by Vogt, 'Lectures on Man,' Eng. translat. 1864, p. +189: for further facts on negro infants, as quoted from Winterbottom and +Camper, see Lawrence, 'Lectures on Physiology,' etc. 1822, p. 451. For the +infants of the Guaranys, see Rengger, 'Säugethiere,' etc. s. 3. See also +Godron, 'De l'Espèce,' tom. ii. 1859, p. 253. For the Australians, Waitz, +'Introduction to Anthropology,' Eng. translat. 1863, p. 99.) + +I have specified the foregoing differences between the male and female sex +in mankind, because they are curiously like those of the Quadrumana. With +these animals the female is mature at an earlier age than the male; at +least this is certainly the case in Cebus azarae. (7. Rengger, +'Säugethiere,' etc., 1830, s. 49.) The males of most species are larger +and stronger than the females, of which fact the gorilla affords a well- +known instance. Even in so trifling a character as the greater prominence +of the superciliary ridge, the males of certain monkeys differ from the +females (8. As in Macacus cynomolgus (Desmarest, 'Mammalogie,' p. 65), and +in Hylobates agilis (Geoffroy St.-Hilaire and F. Cuvier, 'Histoire Nat. des +Mammifères,' 1824, tom. i. p. 2).), and agree in this respect with mankind. +In the gorilla and certain other monkeys, the cranium of the adult male +presents a strongly-marked sagittal crest, which is absent in the female; +and Ecker found a trace of a similar difference between the two sexes in +the Australians. (9. 'Anthropological Review,' Oct. 1868, p. 353.) With +monkeys when there is any difference in the voice, that of the male is the +more powerful. We have seen that certain male monkeys have a well- +developed beard, which is quite deficient, or much less developed in the +female. No instance is known of the beard, whiskers, or moustache being +larger in the female than in the male monkey. Even in the colour of the +beard there is a curious parallelism between man and the Quadrumana, for +with man when the beard differs in colour from the hair of the head, as is +commonly the case, it is, I believe, almost always of a lighter tint, being +often reddish. I have repeatedly observed this fact in England; but two +gentlemen have lately written to me, saying that they form an exception to +the rule. One of these gentlemen accounts for the fact by the wide +difference in colour of the hair on the paternal and maternal sides of his +family. Both had been long aware of this peculiarity (one of them having +often been accused of dyeing his beard), and had been thus led to observe +other men, and were convinced that the exceptions were very rare. Dr. +Hooker attended to this little point for me in Russia, and found no +exception to the rule. In Calcutta, Mr. J. Scott, of the Botanic Gardens, +was so kind as to observe the many races of men to be seen there, as well +as in some other parts of India, namely, two races of Sikhim, the Bhoteas, +Hindoos, Burmese, and Chinese, most of which races have very little hair on +the face; and he always found that when there was any difference in colour +between the hair of the head and the beard, the latter was invariably +lighter. Now with monkeys, as has already been stated, the beard +frequently differs strikingly in colour from the hair of the head, and in +such cases it is always of a lighter hue, being often pure white, sometimes +yellow or reddish. (10. Mr. Blyth informs me that he has only seen one +instance of the beard, whiskers, etc., in a monkey becoming white with old +age, as is so commonly the case with us. This, however, occurred in an +aged Macacus cynomolgus, kept in confinement whose moustaches were +"remarkably long and human-like." Altogether this old monkey presented a +ludicrous resemblance to one of the reigning monarchs of Europe, after whom +he was universally nick-named. In certain races of man the hair on the +head hardly ever becomes grey; thus Mr. D. Forbes has never, as he informs +me, seen an instance with the Aymaras and Quichuas of South America.) + +In regard to the general hairiness of the body, the women in all races are +less hairy than the men; and in some few Quadrumana the under side of the +body of the female is less hairy than that of the male. (11. This is the +case with the females of several species of Hylobates; see Geoffroy St.- +Hilaire and F. Cuvier, 'Hist. Nat. des Mamm.' tom. i. See also, on H. lar, +'Penny Cyclopedia,' vol. ii. pp. 149, 150.) Lastly, male monkeys, like +men, are bolder and fiercer than the females. They lead the troop, and +when there is danger, come to the front. We thus see how close is the +parallelism between the sexual differences of man and the Quadrumana. With +some few species, however, as with certain baboons, the orang and the +gorilla, there is a considerably greater difference between the sexes, as +in the size of the canine teeth, in the development and colour of the hair, +and especially in the colour of the naked parts of the skin, than in +mankind. + +All the secondary sexual characters of man are highly variable, even within +the limits of the same race; and they differ much in the several races. +These two rules hold good generally throughout the animal kingdom. In the +excellent observations made on board the Novara (12. The results were +deduced by Dr. Weisbach from the measurements made by Drs. K. Scherzer and +Schwarz, see 'Reise der Novara: Anthropolog. Theil,' 1867, ss. 216, 231, +234, 236, 239, 269.), the male Australians were found to exceed the females +by only 65 millim. in height, whilst with the Javans the average excess was +218 millim.; so that in this latter race the difference in height between +the sexes is more than thrice as great as with the Australians. Numerous +measurements were carefully made of the stature, the circumference of the +neck and chest, the length of the back-bone and of the arms, in various +races; and nearly all these measurements shew that the males differ much +more from one another than do the females. This fact indicates that, as +far as these characters are concerned, it is the male which has been +chiefly modified, since the several races diverged from their common stock. + +The development of the beard and the hairiness of the body differ +remarkably in the men of distinct races, and even in different tribes or +families of the same race. We Europeans see this amongst ourselves. In +the Island of St. Kilda, according to Martin (13. 'Voyage to St. Kilda' +(3rd ed. 1753), p. 37.), the men do not acquire beards until the age of +thirty or upwards, and even then the beards are very thin. On the +Europaeo-Asiatic continent, beards prevail until we pass beyond India; +though with the natives of Ceylon they are often absent, as was noticed in +ancient times by Diodorus. (14. Sir J.E. Tennent, 'Ceylon,' vol. ii. +1859, p. 107.) Eastward of India beards disappear, as with the Siamese, +Malays, Kalmucks, Chinese, and Japanese; nevertheless, the Ainos (15. +Quatrefages, 'Revue des Cours Scientifiques,' Aug. 29, 1868, p. 630; Vogt, +'Lectures on Man,' Eng. trans. p. 127.), who inhabit the northernmost +islands of the Japan Archipelago, are the hairiest men in the world. With +negroes the beard is scanty or wanting, and they rarely have whiskers; in +both sexes the body is frequently almost destitute of fine down. (16. On +the beards of negroes, Vogt, 'Lectures,' etc. p. 127; Waitz, 'Introduct. to +Anthropology,' Engl. translat. 1863, vol. i. p. 96. It is remarkable that +in the United States ('Investigations in Military and Anthropological +Statistics of American Soldiers,' 1869, p. 569) the pure negroes and their +crossed offspring seem to have bodies almost as hairy as Europeans.) On +the other hand, the Papuans of the Malay Archipelago, who are nearly as +black as negroes, possess well-developed beards. (17. Wallace, 'The Malay +Arch.' vol. ii. 1869, p. 178.) In the Pacific Ocean the inhabitants of the +Fiji Archipelago have large bushy beards, whilst those of the not distant +archipelagoes of Tonga and Samoa are beardless; but these men belong to +distinct races. In the Ellice group all the inhabitants belong to the same +race; yet on one island alone, namely Nunemaya, "the men have splendid +beards"; whilst on the other islands "they have, as a rule, a dozen +straggling hairs for a beard." (18. Dr. J. Barnard Davis on Oceanic +Races, in 'Anthropological Review,' April 1870, pp. 185, 191.) + +Throughout the great American continent the men may be said to be +beardless; but in almost all the tribes a few short hairs are apt to appear +on the face, especially in old age. With the tribes of North America, +Catlin estimates that eighteen out of twenty men are completely destitute +by nature of a beard; but occasionally there may be seen a man, who has +neglected to pluck out the hairs at puberty, with a soft beard an inch or +two in length. The Guaranys of Paraguay differ from all the surrounding +tribes in having a small beard, and even some hair on the body, but no +whiskers. (19. Catlin, 'North American Indians,' 3rd. ed. 1842, vol. ii. +p. 227. On the Guaranys, see Azara, 'Voyages dans l'Amérique Merid.' tom. +ii. 1809, p. 85; also Rengger, 'Säugethiere von Paraguay,' s. 3.) I am +informed by Mr. D. Forbes, who particularly attended to this point, that +the Aymaras and Quichuas of the Cordillera are remarkably hairless, yet in +old age a few straggling hairs occasionally appear on the chin. The men of +these two tribes have very little hair on the various parts of the body +where hair grows abundantly in Europeans, and the women have none on the +corresponding parts. The hair on the head, however, attains an +extraordinary length in both sexes, often reaching almost to the ground; +and this is likewise the case with some of the N. American tribes. In the +amount of hair, and in the general shape of the body, the sexes of the +American aborigines do not differ so much from each other, as in most other +races. (20. Prof. and Mrs. Agassiz ('Journey in Brazil,' p. 530) remark +that the sexes of the American Indians differ less than those of the +negroes and of the higher races. See also Rengger, ibid. p. 3, on the +Guaranys.) This fact is analogous with what occurs with some closely +allied monkeys; thus the sexes of the chimpanzee are not as different as +those of the orang or gorilla. (21. Rutimeyer, 'Die Grenzen der +Thierwelt; eine Betrachtung zu Darwin's Lehre,' 1868, s. 54.) + +In the previous chapters we have seen that with mammals, birds, fishes, +insects, etc., many characters, which there is every reason to believe were +primarily gained through sexual selection by one sex, have been transferred +to the other. As this same form of transmission has apparently prevailed +much with mankind, it will save useless repetition if we discuss the origin +of characters peculiar to the male sex together with certain other +characters common to both sexes. + +LAW OF BATTLE. + +With savages, for instance, the Australians, the women are the constant +cause of war both between members of the same tribe and between distinct +tribes. So no doubt it was in ancient times; "nam fuit ante Helenam mulier +teterrima belli causa." With some of the North American Indians, the +contest is reduced to a system. That excellent observer, Hearne (22. 'A +Journey from Prince of Wales Fort,' 8vo. ed. Dublin, 1796, p. 104. Sir J. +Lubbock ('Origin of Civilisation,' 1870, p. 69) gives other and similar +cases in North America. For the Guanas of South America see Azara, +'Voyages,' etc. tom. ii. p. 94.), says:--"It has ever been the custom among +these people for the men to wrestle for any woman to whom they are +attached; and, of course, the strongest party always carries off the prize. +A weak man, unless he be a good hunter, and well-beloved, is seldom +permitted to keep a wife that a stronger man thinks worth his notice. This +custom prevails throughout all the tribes, and causes a great spirit of +emulation among their youth, who are upon all occasions, from their +childhood, trying their strength and skill in wrestling." With the Guanas +of South America, Azara states that the men rarely marry till twenty years +old or more, as before that age they cannot conquer their rivals. + +Other similar facts could be given; but even if we had no evidence on this +head, we might feel almost sure, from the analogy of the higher Quadrumana +(23. On the fighting of the male gorillas, see Dr. Savage, in 'Boston +Journal of Natural History,' vol. v. 1847, p. 423. On Presbytis entellus, +see the 'Indian Field,' 1859, p. 146.), that the law of battle had +prevailed with man during the early stages of his development. The +occasional appearance at the present day of canine teeth which project +above the others, with traces of a diastema or open space for the reception +of the opposite canines, is in all probability a case of reversion to a +former state, when the progenitors of man were provided with these weapons, +like so many existing male Quadrumana. It was remarked in a former chapter +that as man gradually became erect, and continually used his hands and arms +for fighting with sticks and stones, as well as for the other purposes of +life, he would have used his jaws and teeth less and less. The jaws, +together with their muscles, would then have been reduced through disuse, +as would the teeth through the not well understood principles of +correlation and economy of growth; for we everywhere see that parts, which +are no longer of service, are reduced in size. By such steps the original +inequality between the jaws and teeth in the two sexes of mankind would +ultimately have been obliterated. The case is almost parallel with that of +many male Ruminants, in which the canine teeth have been reduced to mere +rudiments, or have disappeared, apparently in consequence of the +development of horns. As the prodigious difference between the skulls of +the two sexes in the orang and gorilla stands in close relation with the +development of the immense canine teeth in the males, we may infer that the +reduction of the jaws and teeth in the early male progenitors of man must +have led to a most striking and favourable change in his appearance. + +There can be little doubt that the greater size and strength of man, in +comparison with woman, together with his broader shoulders, more developed +muscles, rugged outline of body, his greater courage and pugnacity, are all +due in chief part to inheritance from his half-human male ancestors. These +characters would, however, have been preserved or even augmented during the +long ages of man's savagery, by the success of the strongest and boldest +men, both in the general struggle for life and in their contests for wives; +a success which would have ensured their leaving a more numerous progeny +than their less favoured brethren. It is not probable that the greater +strength of man was primarily acquired through the inherited effects of his +having worked harder than woman for his own subsistence and that of his +family; for the women in all barbarous nations are compelled to work at +least as hard as the men. With civilised people the arbitrament of battle +for the possession of the women has long ceased; on the other hand, the +men, as a general rule, have to work harder than the women for their joint +subsistence, and thus their greater strength will have been kept up. + +DIFFERENCE IN THE MENTAL POWERS OF THE TWO SEXES. + +With respect to differences of this nature between man and woman, it is +probable that sexual selection has played a highly important part. I am +aware that some writers doubt whether there is any such inherent +difference; but this is at least probable from the analogy of the lower +animals which present other secondary sexual characters. No one disputes +that the bull differs in disposition from the cow, the wild-boar from the +sow, the stallion from the mare, and, as is well known to the keepers of +menageries, the males of the larger apes from the females. Woman seems to +differ from man in mental disposition, chiefly in her greater tenderness +and less selfishness; and this holds good even with savages, as shewn by a +well-known passage in Mungo Park's Travels, and by statements made by many +other travellers. Woman, owing to her maternal instincts, displays these +qualities towards her infants in an eminent degree; therefore it is likely +that she would often extend them towards her fellow-creatures. Man is the +rival of other men; he delights in competition, and this leads to ambition +which passes too easily into selfishness. These latter qualities seem to +be his natural and unfortunate birthright. It is generally admitted that +with woman the powers of intuition, of rapid perception, and perhaps of +imitation, are more strongly marked than in man; but some, at least, of +these faculties are characteristic of the lower races, and therefore of a +past and lower state of civilisation. + +The chief distinction in the intellectual powers of the two sexes is shewn +by man's attaining to a higher eminence, in whatever he takes up, than can +woman--whether requiring deep thought, reason, or imagination, or merely +the use of the senses and hands. If two lists were made of the most +eminent men and women in poetry, painting, sculpture, music (inclusive both +of composition and performance), history, science, and philosophy, with +half-a-dozen names under each subject, the two lists would not bear +comparison. We may also infer, from the law of the deviation from +averages, so well illustrated by Mr. Galton, in his work on 'Hereditary +Genius,' that if men are capable of a decided pre-eminence over women in +many subjects, the average of mental power in man must be above that of +woman. + +Amongst the half-human progenitors of man, and amongst savages, there have +been struggles between the males during many generations for the possession +of the females. But mere bodily strength and size would do little for +victory, unless associated with courage, perseverance, and determined +energy. With social animals, the young males have to pass through many a +contest before they win a female, and the older males have to retain their +females by renewed battles. They have, also, in the case of mankind, to +defend their females, as well as their young, from enemies of all kinds, +and to hunt for their joint subsistence. But to avoid enemies or to attack +them with success, to capture wild animals, and to fashion weapons, +requires the aid of the higher mental faculties, namely, observation, +reason, invention, or imagination. These various faculties will thus have +been continually put to the test and selected during manhood; they will, +moreover, have been strengthened by use during this same period of life. +Consequently in accordance with the principle often alluded to, we might +expect that they would at least tend to be transmitted chiefly to the male +offspring at the corresponding period of manhood. + +Now, when two men are put into competition, or a man with a woman, both +possessed of every mental quality in equal perfection, save that one has +higher energy, perseverance, and courage, the latter will generally become +more eminent in every pursuit, and will gain the ascendancy. (24. J. +Stuart Mill remarks ('The Subjection of Women,' 1869, p. 122), "The things +in which man most excels woman are those which require most plodding, and +long hammering at single thoughts." What is this but energy and +perseverance?) He may be said to possess genius--for genius has been +declared by a great authority to be patience; and patience, in this sense, +means unflinching, undaunted perseverance. But this view of genius is +perhaps deficient; for without the higher powers of the imagination and +reason, no eminent success can be gained in many subjects. These latter +faculties, as well as the former, will have been developed in man, partly +through sexual selection,--that is, through the contest of rival males, and +partly through natural selection, that is, from success in the general +struggle for life; and as in both cases the struggle will have been during +maturity, the characters gained will have been transmitted more fully to +the male than to the female offspring. It accords in a striking manner +with this view of the modification and re-inforcement of many of our mental +faculties by sexual selection, that, firstly, they notoriously undergo a +considerable change at puberty (25. Maudsley, 'Mind and Body,' p. 31.), +and, secondly, that eunuchs remain throughout life inferior in these same +qualities. Thus, man has ultimately become superior to woman. It is, +indeed, fortunate that the law of the equal transmission of characters to +both sexes prevails with mammals; otherwise, it is probable that man would +have become as superior in mental endowment to woman, as the peacock is in +ornamental plumage to the peahen. + +It must be borne in mind that the tendency in characters acquired by either +sex late in life, to be transmitted to the same sex at the same age, and of +early acquired characters to be transmitted to both sexes, are rules which, +though general, do not always hold. If they always held good, we might +conclude (but I here exceed my proper bounds) that the inherited effects of +the early education of boys and girls would be transmitted equally to both +sexes; so that the present inequality in mental power between the sexes +would not be effaced by a similar course of early training; nor can it have +been caused by their dissimilar early training. In order that woman should +reach the same standard as man, she ought, when nearly adult, to be trained +to energy and perseverance, and to have her reason and imagination +exercised to the highest point; and then she would probably transmit these +qualities chiefly to her adult daughters. All women, however, could not be +thus raised, unless during many generations those who excelled in the above +robust virtues were married, and produced offspring in larger numbers than +other women. As before remarked of bodily strength, although men do not +now fight for their wives, and this form of selection has passed away, yet +during manhood, they generally undergo a severe struggle in order to +maintain themselves and their families; and this will tend to keep up or +even increase their mental powers, and, as a consequence, the present +inequality between the sexes. (26. An observation by Vogt bears on this +subject: he says, "It is a remarkable circumstance, that the difference +between the sexes, as regards the cranial cavity, increases with the +development of the race, so that the male European excels much more the +female, than the negro the negress. Welcker confirms this statement of +Huschke from his measurements of negro and German skulls." But Vogt admits +('Lectures on Man,' Eng. translat. 1864, p. 81) that more observations are +requisite on this point. + +VOICE AND MUSICAL POWERS. + +In some species of Quadrumana there is a great difference between the adult +sexes, in the power of their voices and in the development of the vocal +organs; and man appears to have inherited this difference from his early +progenitors. His vocal cords are about one-third longer than in woman, or +than in boys; and emasculation produces the same effect on him as on the +lower animals, for it "arrests that prominent growth of the thyroid, etc., +which accompanies the elongation of the cords." (27. Owen, 'Anatomy of +Vertebrates,' vol. iii. p. 603.) With respect to the cause of this +difference between the sexes, I have nothing to add to the remarks in the +last chapter on the probable effects of the long-continued use of the vocal +organs by the male under the excitement of love, rage and jealousy. +According to Sir Duncan Gibb (28. 'Journal of the Anthropological +Society,' April 1869, p. lvii. and lxvi.), the voice and the form of the +larynx differ in the different races of mankind; but with the Tartars, +Chinese, etc., the voice of the male is said not to differ so much from +that of the female, as in most other races. + +The capacity and love for singing or music, though not a sexual character +in man, must not here be passed over. Although the sounds emitted by +animals of all kinds serve many purposes, a strong case can be made out, +that the vocal organs were primarily used and perfected in relation to the +propagation of the species. Insects and some few spiders are the lowest +animals which voluntarily produce any sound; and this is generally effected +by the aid of beautifully constructed stridulating organs, which are often +confined to the males. The sounds thus produced consist, I believe in all +cases, of the same note, repeated rhythmically (29. Dr. Scudder, 'Notes on +Stridulation,' in 'Proc. Boston Soc. of Nat. Hist.' vol. xi. April 1868.); +and this is sometimes pleasing even to the ears of man. The chief and, in +some cases, exclusive purpose appears to be either to call or charm the +opposite sex. + +The sounds produced by fishes are said in some cases to be made only by the +males during the breeding-season. All the air-breathing Vertebrata +necessarily possess an apparatus for inhaling and expelling air, with a +pipe capable of being closed at one end. Hence when the primeval members +of this class were strongly excited and their muscles violently contracted, +purposeless sounds would almost certainly have been produced; and these, if +they proved in any way serviceable, might readily have been modified or +intensified by the preservation of properly adapted variations. The lowest +Vertebrates which breathe air are Amphibians; and of these, frogs and toads +possess vocal organs, which are incessantly used during the breeding- +season, and which are often more highly developed in the male than in the +female. The male alone of the tortoise utters a noise, and this only +during the season of love. Male alligators roar or bellow during the same +season. Every one knows how much birds use their vocal organs as a means +of courtship; and some species likewise perform what may be called +instrumental music. + +In the class of Mammals, with which we are here more particularly +concerned, the males of almost all the species use their voices during the +breeding-season much more than at any other time; and some are absolutely +mute excepting at this season. With other species both sexes, or only the +females, use their voices as a love-call. Considering these facts, and +that the vocal organs of some quadrupeds are much more largely developed in +the male than in the female, either permanently or temporarily during the +breeding-season; and considering that in most of the lower classes the +sounds produced by the males, serve not only to call but to excite or +allure the female, it is a surprising fact that we have not as yet any good +evidence that these organs are used by male mammals to charm the females. +The American Mycetes caraya perhaps forms an exception, as does the +Hylobates agilis, an ape allied to man. This gibbon has an extremely loud +but musical voice. Mr. Waterhouse states (30. Given in W.C.L. Martin's +'General Introduction to Natural History of Mamm. Animals,' 1841, p. 432; +Owen, 'Anatomy of Vertebrates,' vol. iii, p. 600.), "It appeared to me that +in ascending and descending the scale, the intervals were always exactly +half-tones; and I am sure that the highest note was the exact octave to the +lowest. The quality of the notes is very musical; and I do not doubt that +a good violinist would be able to give a correct idea of the gibbon's +composition, excepting as regards its loudness." Mr. Waterhouse then gives +the notes. Professor Owen, who is a musician, confirms the foregoing +statement, and remarks, though erroneously, that this gibbon "alone of +brute mammals may be said to sing." It appears to be much excited after +its performance. Unfortunately, its habits have never been closely +observed in a state of nature; but from the analogy of other animals, it is +probable that it uses its musical powers more especially during the season +of courtship. + +This gibbon is not the only species in the genus which sings, for my son, +Francis Darwin, attentively listened in the Zoological Gardens to H. +leuciscus whilst singing a cadence of three notes, in true musical +intervals and with a clear musical tone. It is a more surprising fact that +certain rodents utter musical sounds. Singing mice have often been +mentioned and exhibited, but imposture has commonly been suspected. We +have, however, at last a clear account by a well-known observer, the Rev. +S. Lockwood (31. The 'American Naturalist,' 1871, p. 761.), of the musical +powers of an American species, the Hesperomys cognatus, belonging to a +genus distinct from that of the English mouse. This little animal was kept +in confinement, and the performance was repeatedly heard. In one of the +two chief songs, "the last bar would frequently be prolonged to two or +three; and she would sometimes change from C sharp and D, to C natural and +D, then warble on these two notes awhile, and wind up with a quick chirp on +C sharp and D. The distinctness between the semitones was very marked, and +easily appreciable to a good ear." Mr. Lockwood gives both songs in +musical notation; and adds that though this little mouse "had no ear for +time, yet she would keep to the key of B (two flats) and strictly in a +major key."..."Her soft clear voice falls an octave with all the precision +possible; then at the wind up, it rises again into a very quick trill on C +sharp and D." + +A critic has asked how the ears of man, and he ought to have added of other +animals, could have been adapted by selection so as to distinguish musical +notes. But this question shews some confusion on the subject; a noise is +the sensation resulting from the co-existence of several aerial "simple +vibrations" of various periods, each of which intermits so frequently that +its separate existence cannot be perceived. It is only in the want of +continuity of such vibrations, and in their want of harmony inter se, that +a noise differs from a musical note. Thus an ear to be capable of +discriminating noises--and the high importance of this power to all animals +is admitted by every one--must be sensitive to musical notes. We have +evidence of this capacity even low down in the animal scale: thus +Crustaceans are provided with auditory hairs of different lengths, which +have been seen to vibrate when the proper musical notes are struck. (32. +Helmholtz, 'Theorie Phys. de la Musique,' 1868, p. 187.) As stated in a +previous chapter, similar observations have been made on the hairs of the +antennae of gnats. It has been positively asserted by good observers that +spiders are attracted by music. It is also well known that some dogs howl +when hearing particular tones. (33. Several accounts have been published +to this effect. Mr. Peach writes to me that an old dog of his howls when B +flat is sounded on the flute, and to no other note. I may add another +instance of a dog always whining, when one note on a concertina, which was +out of tune, was played.) Seals apparently appreciate music, and their +fondness for it "was well known to the ancients, and is often taken +advantage of by the hunters at the present day." (34. Mr. R. Brown, in +'Proc. Zool. Soc.' 1868, p. 410.) + +Therefore, as far as the mere perception of musical notes is concerned, +there seems no special difficulty in the case of man or of any other +animal. Helmholtz has explained on physiological principles why concords +are agreeable, and discords disagreeable to the human ear; but we are +little concerned with these, as music in harmony is a late invention. We +are more concerned with melody, and here again, according to Helmholtz, it +is intelligible why the notes of our musical scale are used. The ear +analyses all sounds into their component "simple vibrations," although we +are not conscious of this analysis. In a musical note the lowest in pitch +of these is generally predominant, and the others which are less marked are +the octave, the twelfth, the second octave, etc., all harmonies of the +fundamental predominant note; any two notes of our scale have many of these +harmonic over-tones in common. It seems pretty clear then, that if an +animal always wished to sing precisely the same song, he would guide +himself by sounding those notes in succession, which possess many over- +tones in common--that is, he would choose for his song, notes which belong +to our musical scale. + +But if it be further asked why musical tones in a certain order and rhythm +give man and other animals pleasure, we can no more give the reason than +for the pleasantness of certain tastes and smells. That they do give +pleasure of some kind to animals, we may infer from their being produced +during the season of courtship by many insects, spiders, fishes, +amphibians, and birds; for unless the females were able to appreciate such +sounds and were excited or charmed by them, the persevering efforts of the +males, and the complex structures often possessed by them alone, would be +useless; and this it is impossible to believe. + +Human song is generally admitted to be the basis or origin of instrumental +music. As neither the enjoyment nor the capacity of producing musical +notes are faculties of the least use to man in reference to his daily +habits of life, they must be ranked amongst the most mysterious with which +he is endowed. They are present, though in a very rude condition, in men +of all races, even the most savage; but so different is the taste of the +several races, that our music gives no pleasure to savages, and their music +is to us in most cases hideous and unmeaning. Dr. Seemann, in some +interesting remarks on this subject (35. 'Journal of Anthropological +Society,' Oct. 1870, p. clv. See also the several later chapters in Sir +John Lubbock's 'Prehistoric Times,' 2nd ed. 1869, which contain an +admirable account of the habits of savages.), "doubts whether even amongst +the nations of Western Europe, intimately connected as they are by close +and frequent intercourse, the music of the one is interpreted in the same +sense by the others. By travelling eastwards we find that there is +certainly a different language of music. Songs of joy and dance- +accompaniments are no longer, as with us, in the major keys, but always in +the minor." Whether or not the half-human progenitors of man possessed, +like the singing gibbons, the capacity of producing, and therefore no doubt +of appreciating, musical notes, we know that man possessed these faculties +at a very remote period. M. Lartet has described two flutes made out of +the bones and horns of the reindeer, found in caves together with flint +tools and the remains of extinct animals. The arts of singing and of +dancing are also very ancient, and are now practised by all or nearly all +the lowest races of man. Poetry, which may be considered as the offspring +of song, is likewise so ancient, that many persons have felt astonished +that it should have arisen during the earliest ages of which we have any +record. + +We see that the musical faculties, which are not wholly deficient in any +race, are capable of prompt and high development, for Hottentots and +Negroes have become excellent musicians, although in their native countries +they rarely practise anything that we should consider music. Schweinfurth, +however, was pleased with some of the simple melodies which he heard in the +interior of Africa. But there is nothing anomalous in the musical +faculties lying dormant in man: some species of birds which never +naturally sing, can without much difficulty be taught to do so; thus a +house-sparrow has learnt the song of a linnet. As these two species are +closely allied, and belong to the order of Insessores, which includes +nearly all the singing-birds in the world, it is possible that a progenitor +of the sparrow may have been a songster. It is more remarkable that +parrots, belonging to a group distinct from the Insessores, and having +differently constructed vocal organs, can be taught not only to speak, but +to pipe or whistle tunes invented by man, so that they must have some +musical capacity. Nevertheless it would be very rash to assume that +parrots are descended from some ancient form which was a songster. Many +cases could be advanced of organs and instincts originally adapted for one +purpose, having been utilised for some distinct purpose. (36. Since this +chapter was printed, I have seen a valuable article by Mr. Chauncey Wright +('North American Review,' Oct. 1870, page 293), who, in discussing the +above subject, remarks, "There are many consequences of the ultimate laws +or uniformities of nature, through which the acquisition of one useful +power will bring with it many resulting advantages as well as limiting +disadvantages, actual or possible, which the principle of utility may not +have comprehended in its action." As I have attempted to shew in an early +chapter of this work, this principle has an important bearing on the +acquisition by man of some of his mental characteristics.) Hence the +capacity for high musical development which the savage races of man +possess, may be due either to the practice by our semi-human progenitors of +some rude form of music, or simply to their having acquired the proper +vocal organs for a different purpose. But in this latter case we must +assume, as in the above instance of parrots, and as seems to occur with +many animals, that they already possessed some sense of melody. + +Music arouses in us various emotions, but not the more terrible ones of +horror, fear, rage, etc. It awakens the gentler feelings of tenderness and +love, which readily pass into devotion. In the Chinese annals it is said, +"Music hath the power of making heaven descend upon earth." It likewise +stirs up in us the sense of triumph and the glorious ardour for war. These +powerful and mingled feelings may well give rise to the sense of sublimity. +We can concentrate, as Dr. Seemann observes, greater intensity of feeling +in a single musical note than in pages of writing. It is probable that +nearly the same emotions, but much weaker and far less complex, are felt by +birds when the male pours forth his full volume of song, in rivalry with +other males, to captivate the female. Love is still the commonest theme of +our songs. As Herbert Spencer remarks, "music arouses dormant sentiments +of which we had not conceived the possibility, and do not know the meaning; +or, as Richter says, tells us of things we have not seen and shall not +see." Conversely, when vivid emotions are felt and expressed by the +orator, or even in common speech, musical cadences and rhythm are +instinctively used. The negro in Africa when excited often bursts forth in +song; "another will reply in song, whilst the company, as if touched by a +musical wave, murmur a chorus in perfect unison." (37. Winwood Reade, +'The Martyrdom of Man,' 1872, p. 441, and 'African Sketch Book,' 1873, vol. +ii. p. 313.) Even monkeys express strong feelings in different tones-- +anger and impatience by low,--fear and pain by high notes. (38. Rengger, +'Säugethiere von Paraguay,' s. 49.) The sensations and ideas thus excited +in us by music, or expressed by the cadences of oratory, appear from their +vagueness, yet depth, like mental reversions to the emotions and thoughts +of a long-past age. + +All these facts with respect to music and impassioned speech become +intelligible to a certain extent, if we may assume that musical tones and +rhythm were used by our half-human ancestors, during the season of +courtship, when animals of all kinds are excited not only by love, but by +the strong passions of jealousy, rivalry, and triumph. From the deeply- +laid principle of inherited associations, musical tones in this case would +be likely to call up vaguely and indefinitely the strong emotions of a +long-past age. As we have every reason to suppose that articulate speech +is one of the latest, as it certainly is the highest, of the arts acquired +by man, and as the instinctive power of producing musical notes and rhythms +is developed low down in the animal series, it would be altogether opposed +to the principle of evolution, if we were to admit that man's musical +capacity has been developed from the tones used in impassioned speech. We +must suppose that the rhythms and cadences of oratory are derived from +previously developed musical powers. (39. See the very interesting +discussion on the 'Origin and Function of Music,' by Mr. Herbert Spencer, +in his collected 'Essays,' 1858, p. 359. Mr. Spencer comes to an exactly +opposite conclusion to that at which I have arrived. He concludes, as did +Diderot formerly, that the cadences used in emotional speech afford the +foundation from which music has been developed; whilst I conclude that +musical notes and rhythm were first acquired by the male or female +progenitors of mankind for the sake of charming the opposite sex. Thus +musical tones became firmly associated with some of the strongest passions +an animal is capable of feeling, and are consequently used instinctively, +or through association when strong emotions are expressed in speech. Mr. +Spencer does not offer any satisfactory explanation, nor can I, why high or +deep notes should be expressive, both with man and the lower animals, of +certain emotions. Mr. Spencer gives also an interesting discussion on the +relations between poetry, recitative and song.) We can thus understand how +it is that music, dancing, song, and poetry are such very ancient arts. We +may go even further than this, and, as remarked in a former chapter, +believe that musical sounds afforded one of the bases for the development +of language. (40. I find in Lord Monboddo's 'Origin of Language,' vol. i. +1774, p. 469, that Dr. Blacklock likewise thought "that the first language +among men was music, and that before our ideas were expressed by articulate +sounds, they were communicated by tones varied according to different +degrees of gravity and acuteness.") + +As the males of several quadrumanous animals have their vocal organs much +more developed than in the females, and as a gibbon, one of the +anthropomorphous apes, pours forth a whole octave of musical notes and may +be said to sing, it appears probable that the progenitors of man, either +the males or females or both sexes, before acquiring the power of +expressing their mutual love in articulate language, endeavoured to charm +each other with musical notes and rhythm. So little is known about the use +of the voice by the Quadrumana during the season of love, that we have no +means of judging whether the habit of singing was first acquired by our +male or female ancestors. Women are generally thought to possess sweeter +voices than men, and as far as this serves as any guide, we may infer that +they first acquired musical powers in order to attract the other sex. (41. +See an interesting discussion on this subject by Haeckel, 'Generelle +Morphologie,' B. ii. 1866, s. 246.) But if so, this must have occurred +long ago, before our ancestors had become sufficiently human to treat and +value their women merely as useful slaves. The impassioned orator, bard, +or musician, when with his varied tones and cadences he excites the +strongest emotions in his hearers, little suspects that he uses the same +means by which his half-human ancestors long ago aroused each other's +ardent passions, during their courtship and rivalry. + +THE INFLUENCE OF BEAUTY IN DETERMINING THE MARRIAGES OF MANKIND. + +In civilised life man is largely, but by no means exclusively, influenced +in the choice of his wife by external appearance; but we are chiefly +concerned with primeval times, and our only means of forming a judgment on +this subject is to study the habits of existing semi-civilised and savage +nations. If it can be shewn that the men of different races prefer women +having various characteristics, or conversely with the women, we have then +to enquire whether such choice, continued during many generations, would +produce any sensible effect on the race, either on one sex or both +according to the form of inheritance which has prevailed. + +It will be well first to shew in some detail that savages pay the greatest +attention to their personal appearance. (42. A full and excellent account +of the manner in which savages in all parts of the world ornament +themselves, is given by the Italian traveller, Professor Mantegazza, 'Rio +de la Plata, Viaggi e Studi,' 1867, pp. 525-545; all the following +statements, when other references are not given, are taken from this work. +See, also, Waitz, 'Introduction to Anthropology,' Eng. translat. vol. i. +1863, p. 275, et passim. Lawrence also gives very full details in his +'Lectures on Physiology,' 1822. Since this chapter was written Sir J. +Lubbock has published his 'Origin of Civilisation,' 1870, in which there is +an interesting chapter on the present subject, and from which (pp. 42, 48) +I have taken some facts about savages dyeing their teeth and hair, and +piercing their teeth.) That they have a passion for ornament is notorious; +and an English philosopher goes so far as to maintain, that clothes were +first made for ornament and not for warmth. As Professor Waitz remarks, +"however poor and miserable man is, he finds a pleasure in adorning +himself." The extravagance of the naked Indians of South America in +decorating themselves is shewn "by a man of large stature gaining with +difficulty enough by the labour of a fortnight to procure in exchange the +chica necessary to paint himself red." (43. Humboldt, 'Personal +Narrative,' Eng. translat. vol. iv. p. 515; on the imagination shewn in +painting the body, p. 522; on modifying the form of the calf of the leg, p. +466.) The ancient barbarians of Europe during the Reindeer period brought +to their caves any brilliant or singular objects which they happened to +find. Savages at the present day everywhere deck themselves with plumes, +necklaces, armlets, ear-rings, etc. They paint themselves in the most +diversified manner. "If painted nations," as Humboldt observes, "had been +examined with the same attention as clothed nations, it would have been +perceived that the most fertile imagination and the most mutable caprice +have created the fashions of painting, as well as those of garments." + +In one part of Africa the eyelids are coloured black; in another the nails +are coloured yellow or purple. In many places the hair is dyed of various +tints. In different countries the teeth are stained black, red, blue, +etc., and in the Malay Archipelago it is thought shameful to have white +teeth "like those of a dog." Not one great country can be named, from the +polar regions in the north to New Zealand in the south, in which the +aborigines do not tattoo themselves. This practice was followed by the +Jews of old, and by the ancient Britons. In Africa some of the natives +tattoo themselves, but it is a much more common practice to raise +protuberances by rubbing salt into incisions made in various parts of the +body; and these are considered by the inhabitants of Kordofan and Darfur +"to be great personal attractions." In the Arab countries no beauty can be +perfect until the cheeks "or temples have been gashed." (44. 'The Nile +Tributaries,' 1867; 'The Albert N'yanza,' 1866, vol. i. p. 218.) In South +America, as Humboldt remarks, "a mother would be accused of culpable +indifference towards her children, if she did not employ artificial means +to shape the calf of the leg after the fashion of the country." In the Old +and New Worlds the shape of the skull was formerly modified during infancy +in the most extraordinary manner, as is still the case in many places, and +such deformities are considered ornamental. For instance, the savages of +Colombia (45. Quoted by Prichard, 'Physical History of Mankind,' 4th ed. +vol. i. 1851, p. 321.) deem a much flattened head "an essential point of +beauty." + +The hair is treated with especial care in various countries; it is allowed +to grow to full length, so as to reach to the ground, or is combed into "a +compact frizzled mop, which is the Papuan's pride and glory." (46. On the +Papuans, Wallace, 'The Malay Archipelago,' vol. ii. p. 445. On the +coiffure of the Africans, Sir S. Baker, 'The Albert N'yanza,' vol. i. p. +210.) In northern Africa "a man requires a period of from eight to ten +years to perfect his coiffure." With other nations the head is shaved, and +in parts of South America and Africa even the eyebrows and eyelashes are +eradicated. The natives of the Upper Nile knock out the four front teeth, +saying that they do not wish to resemble brutes. Further south, the +Batokas knock out only the two upper incisors, which, as Livingstone (47. +'Travels,' p. 533.) remarks, gives the face a hideous appearance, owing to +the prominence of the lower jaw; but these people think the presence of the +incisors most unsightly, and on beholding some Europeans, cried out, "Look +at the great teeth!" The chief Sebituani tried in vain to alter this +fashion. In various parts of Africa and in the Malay Archipelago the +natives file the incisors into points like those of a saw, or pierce them +with holes, into which they insert studs. + +As the face with us is chiefly admired for its beauty, so with savages it +is the chief seat of mutilation. In all quarters of the world the septum, +and more rarely the wings of the nose are pierced; rings, sticks, feathers, +and other ornaments being inserted into the holes. The ears are everywhere +pierced and similarly ornamented, and with the Botocudos and Lenguas of +South America the hole is gradually so much enlarged that the lower edge +touches the shoulder. In North and South America and in Africa either the +upper or lower lip is pierced; and with the Botocudos the hole in the lower +lip is so large that a disc of wood, four inches in diameter, is placed in +it. Mantegazza gives a curious account of the shame felt by a South +American native, and of the ridicule which he excited, when he sold his +tembeta,--the large coloured piece of wood which is passed through the +hole. In Central Africa the women perforate the lower lip and wear a +crystal, which, from the movement of the tongue, has "a wriggling motion, +indescribably ludicrous during conversation." The wife of the chief of +Latooka told Sir S. Baker (49. 'The Albert N'yanza,' 1866, vol. i. p. +217.) that Lady Baker "would be much improved if she would extract her four +front teeth from the lower jaw, and wear the long pointed polished crystal +in her under lip." Further south with the Makalolo, the upper lip is +perforated, and a large metal and bamboo ring, called a pelele, is worn in +the hole. "This caused the lip in one case to project two inches beyond +the tip of the nose; and when the lady smiled, the contraction of the +muscles elevated it over the eyes. 'Why do the women wear these things?' +the venerable chief, Chinsurdi, was asked. Evidently surprised at such a +stupid question, he replied, 'For beauty! They are the only beautiful +things women have; men have beards, women have none. What kind of a person +would she be without the pelele? She would not be a woman at all with a +mouth like a man, but no beard.'" (49. Livingstone, 'British +Association,' 1860; report given in the 'Athenaeum,' July 7, 1860, p. 29.) + +Hardly any part of the body, which can be unnaturally modified, has +escaped. The amount of suffering thus caused must have been extreme, for +many of the operations require several years for their completion, so that +the idea of their necessity must be imperative. The motives are various; +the men paint their bodies to make themselves appear terrible in battle; +certain mutilations are connected with religious rites, or they mark the +age of puberty, or the rank of the man, or they serve to distinguish the +tribes. Amongst savages the same fashions prevail for long periods (50. +Sir S. Baker (ibid. vol. i. p. 210) speaking of the natives of Central +Africa says, "every tribe has a distinct and unchanging fashion for +dressing the hair." See Agassiz ('Journey in Brazil,' 1868, p. 318) on +invariability of the tattooing of Amazonian Indians.), and thus +mutilations, from whatever cause first made, soon come to be valued as +distinctive marks. But self-adornment, vanity, and the admiration of +others, seem to be the commonest motives. In regard to tattooing, I was +told by the missionaries in New Zealand that when they tried to persuade +some girls to give up the practice, they answered, "We must just have a few +lines on our lips; else when we grow old we shall be so very ugly." With +the men of New Zealand, a most capable judge (51. Rev. R. Taylor, 'New +Zealand and its Inhabitants,' 1855, p. 152.) says, "to have fine tattooed +faces was the great ambition of the young, both to render themselves +attractive to the ladies, and conspicuous in war." A star tattooed on the +forehead and a spot on the chin are thought by the women in one part of +Africa to be irresistible attractions. (52. Mantegazza, 'Viaggi e Studi,' +p. 542.) In most, but not all parts of the world, the men are more +ornamented than the women, and often in a different manner; sometimes, +though rarely, the women are hardly at all ornamented. As the women are +made by savages to perform the greatest share of the work, and as they are +not allowed to eat the best kinds of food, so it accords with the +characteristic selfishness of man that they should not be allowed to +obtain, or use the finest ornaments. Lastly, it is a remarkable fact, as +proved by the foregoing quotations, that the same fashions in modifying the +shape of the head, in ornamenting the hair, in painting, tattooing, in +perforating the nose, lips, or ears, in removing or filing the teeth, etc., +now prevail, and have long prevailed, in the most distant quarters of the +world. It is extremely improbable that these practices, followed by so +many distinct nations, should be due to tradition from any common source. +They indicate the close similarity of the mind of man, to whatever race he +may belong, just as do the almost universal habits of dancing, +masquerading, and making rude pictures. + +Having made these preliminary remarks on the admiration felt by savages for +various ornaments, and for deformities most unsightly in our eyes, let us +see how far the men are attracted by the appearance of their women, and +what are their ideas of beauty. I have heard it maintained that savages +are quite indifferent about the beauty of their women, valuing them solely +as slaves; it may therefore be well to observe that this conclusion does +not at all agree with the care which the women take in ornamenting +themselves, or with their vanity. Burchell (53. 'Travels in South +Africa,' 1824, vol. i. p. 414.) gives an amusing account of a Bush-woman +who used as much grease, red ochre, and shining powder "as would have +ruined any but a very rich husband." She displayed also "much vanity and +too evident a consciousness of her superiority." Mr. Winwood Reade informs +me that the negroes of the West Coast often discuss the beauty of their +women. Some competent observers have attributed the fearfully common +practice of infanticide partly to the desire felt by the women to retain +their good looks. (54. See, for references, Gerland, 'Ueber das +Aussterben der Naturvölker,' 1868, ss. 51, 53, 55; also Azara, 'Voyages,' +etc., tom. ii. p. 116.) In several regions the women wear charms and use +love-philters to gain the affections of the men; and Mr. Brown enumerates +four plants used for this purpose by the women of North-Western America. +(55. On the vegetable productions used by the North-Western American +Indians, see 'Pharmaceutical Journal,' vol. x.) + +Hearne (56. 'A Journey from Prince of Wales Fort,' 8vo. ed. 1796, p. 89.), +an excellent observer, who lived many years with the American Indians, +says, in speaking of the women, "Ask a Northern Indian what is beauty, and +he will answer, a broad flat face, small eyes, high cheek-bones, three or +four broad black lines across each cheek, a low forehead, a large broad +chin, a clumsy hook nose, a tawny hide, and breasts hanging down to the +belt." Pallas, who visited the northern parts of the Chinese empire, says, +"those women are preferred who have the Mandschu form; that is to say, a +broad face, high cheek-bones, very broad noses, and enormous ears"(57. +Quoted by Prichard, 'Physical History of Mankind,' 3rd ed. vol. iv. 1844, +p. 519; Vogt, 'Lectures on Man,' Eng. translat. p. 129. On the opinion of +the Chinese on the Cingalese, E. Tennent, 'Ceylon,' 1859, vol. ii. p. +107.); and Vogt remarks that the obliquity of the eye, which is proper to +the Chinese and Japanese, is exaggerated in their pictures for the purpose, +as it "seems, of exhibiting its beauty, as contrasted with the eye of the +red-haired barbarians." It is well known, as Huc repeatedly remarks, that +the Chinese of the interior think Europeans hideous, with their white skins +and prominent noses. The nose is far from being too prominent, according +to our ideas, in the natives of Ceylon; yet "the Chinese in the seventh +century, accustomed to the flat features of the Mongol races, were +surprised at the prominent noses of the Cingalese; and Thsang described +them as having 'the beak of a bird, with the body of a man.'" + +Finlayson, after minutely describing the people of Cochin China, says that +their rounded heads and faces are their chief characteristics; and, he +adds, "the roundness of the whole countenance is more striking in the +women, who are reckoned beautiful in proportion as they display this form +of face." The Siamese have small noses with divergent nostrils, a wide +mouth, rather thick lips, a remarkably large face, with very high and broad +cheek-bones. It is, therefore, not wonderful that "beauty, according to +our notion, is a stranger to them. Yet they consider their own females to +be much more beautiful than those of Europe." (58. Prichard, as taken +from Crawfurd and Finlayson, 'Phys. Hist. of Mankind,' vol. iv. pp. 534, +535.) + +It is well known that with many Hottentot women the posterior part of the +body projects in a wonderful manner; they are steatopygous; and Sir Andrew +Smith is certain that this peculiarity is greatly admired by the men. (59. +Idem illustrissimus viator dixit mihi praecinctorium vel tabulam foeminae, +quod nobis teterrimum est, quondam permagno aestimari ab hominibus in hac +gente. Nunc res mutata est, et censent talem conformationem minime +optandam esse.) He once saw a woman who was considered a beauty, and she +was so immensely developed behind, that when seated on level ground she +could not rise, and had to push herself along until she came to a slope. +Some of the women in various negro tribes have the same peculiarity; and, +according to Burton, the Somal men are said to choose their wives by +ranging them in a line, and by picking her out who projects farthest a +tergo. Nothing can be more hateful to a negro than the opposite form." +(60. The 'Anthropological Review,' November 1864, p. 237. For additional +references, see Waitz, 'Introduction to Anthropology,' Eng. translat., +1863, vol. i. p. 105.) + +With respect to colour, the negroes rallied Mungo Park on the whiteness of +his skin and the prominence of his nose, both of which they considered as +"unsightly and unnatural conformations." He in return praised the glossy +jet of their skins and the lovely depression of their noses; this they said +was "honeymouth," nevertheless they gave him food. The African Moors, +also, "knitted their brows and seemed to shudder" at the whiteness of his +skin. On the eastern coast, the negro boys when they saw Burton, cried +out, "Look at the white man; does he not look like a white ape?" On the +western coast, as Mr. Winwood Reade informs me, the negroes admire a very +black skin more than one of a lighter tint. But their horror of whiteness +may be attributed, according to this same traveller, partly to the belief +held by most negroes that demons and spirits are white, and partly to their +thinking it a sign of ill-health. + +The Banyai of the more southern part of the continent are negroes, but "a +great many of them are of a light coffee-and-milk colour, and, indeed, this +colour is considered handsome throughout the whole country"; so that here +we have a different standard of taste. With the Kaffirs, who differ much +from negroes, "the skin, except among the tribes near Delagoa Bay, is not +usually black, the prevailing colour being a mixture of black and red, the +most common shade being chocolate. Dark complexions, as being most common, +are naturally held in the highest esteem. To be told that he is light- +coloured, or like a white man, would be deemed a very poor compliment by a +Kaffir. I have heard of one unfortunate man who was so very fair that no +girl would marry him." One of the titles of the Zulu king is, "You who are +black." (61. Mungo Park's 'Travels in Africa,' 4to. 1816, pp. 53, 131. +Burton's statement is quoted by Schaaffhausen, 'Archiv. fur Anthropologie,' +1866, s. 163. On the Banyai, Livingstone, 'Travels,' p. 64. On the +Kaffirs, the Rev. J. Shooter, 'The Kafirs of Natal and the Zulu Country,' +1857, p. 1.) Mr. Galton, in speaking to me about the natives of S. Africa, +remarked that their ideas of beauty seem very different from ours; for in +one tribe two slim, slight, and pretty girls were not admired by the +natives. + +Turning to other quarters of the world; in Java, a yellow, not a white +girl, is considered, according to Madame Pfeiffer, a beauty. A man of +Cochin China "spoke with contempt of the wife of the English Ambassador, +that she had white teeth like a dog, and a rosy colour like that of potato- +flowers." We have seen that the Chinese dislike our white skin, and that +the N. Americans admire "a tawny hide." In S. America, the Yuracaras, who +inhabit the wooded, damp slopes of the eastern Cordillera, are remarkably +pale-coloured, as their name in their own language expresses; nevertheless +they consider European women as very inferior to their own. (62. For the +Javans and Cochin-Chinese, see Waitz, 'Introduct. to Anthropology,' Eng. +translat. vol. i. p. 305. On the Yuracaras, A. d'Orbigny, as quoted in +Prichard, 'Physical History of Mankind,' vol. v. 3rd ed. p. 476.) + +In several of the tribes of North America the hair on the head grows to a +wonderful length; and Catlin gives a curious proof how much this is +esteemed, for the chief of the Crows was elected to this office from having +the longest hair of any man in the tribe, namely ten feet and seven inches. +The Aymaras and Quichuas of S. America, likewise have very long hair; and +this, as Mr. D. Forbes informs me, is so much valued as a beauty, that +cutting it off was the severest punishment which he could inflict on them. +In both the Northern and Southern halves of the continent the natives +sometimes increase the apparent length of their hair by weaving into it +fibrous substances. Although the hair on the head is thus cherished, that +on the face is considered by the North American Indians "as very vulgar," +and every hair is carefully eradicated. This practice prevails throughout +the American continent from Vancouver's Island in the north to Tierra del +Fuego in the south. When York Minster, a Fuegian on board the "Beagle," +was taken back to his country, the natives told him be ought to pull out +the few short hairs on his face. They also threatened a young missionary, +who was left for a time with them, to strip him naked, and pluck the hair +from his face and body, yet he was far from being a hairy man. This +fashion is carried so far that the Indians of Paraguay eradicate their +eyebrows and eyelashes, saying that they do not wish to be like horses. +(63. 'North American Indians,' by G. Catlin, 3rd ed., 1842, vol. i. p. 49; +vol. ii, p. 227. On the natives of Vancouver's Island, see Sproat, 'Scenes +and Studies of Savage Life,' 1868, p. 25. On the Indians of Paraguay, +Azara, 'Voyages,' tom. ii. p. 105.) + +It is remarkable that throughout the world the races which are almost +completely destitute of a beard dislike hairs on the face and body, and +take pains to eradicate them. The Kalmucks are beardless, and they are +well known, like the Americans, to pluck out all straggling hairs; and so +it is with the Polynesians, some of the Malays, and the Siamese. Mr. +Veitch states that the Japanese ladies "all objected to our whiskers, +considering them very ugly, and told us to cut them off, and be like +Japanese men." The New Zealanders have short, curled beards; yet they +formerly plucked out the hairs on the face. They had a saying that "there +is no woman for a hairy man;" but it would appear that the fashion has +changed in New Zealand, perhaps owing to the presence of Europeans, and I +am assured that beards are now admired by the Maories. (64. On the +Siamese, Prichard, ibid. vol. iv. p. 533. On the Japanese, Veitch in +'Gardeners' Chronicle,' 1860, p. 1104. On the New Zealanders, Mantegazza, +'Viaggi e Studi,' 1867, p. 526. For the other nations mentioned, see +references in Lawrence, 'Lectures on Physiology,' etc., 1822, p. 272.) + +On the other hand, bearded races admire and greatly value their beards; +among the Anglo-Saxons every part of the body had a recognised value; "the +loss of the beard being estimated at twenty shillings, while the breaking +of a thigh was fixed at only twelve." (65. Lubbock, 'Origin of +Civilisation,' 1870, p. 321.) In the East men swear solemnly by their +beards. We have seen that Chinsurdi, the chief of the Makalolo in Africa, +thought that beards were a great ornament. In the Pacific the Fijian's +beard is "profuse and bushy, and is his greatest pride"; whilst the +inhabitants of the adjacent archipelagoes of Tonga and Samoa are +"beardless, and abhor a rough chin." In one island alone of the Ellice +group "the men are heavily bearded, and not a little proud thereof." (66. +Dr. Barnard Davis quotes Mr. Prichard and others for these facts in regard +to the Polynesians, in 'Anthropolog. Review,' April 1870, pp. 185, 191.) + +We thus see how widely the different races of man differ in their taste for +the beautiful. In every nation sufficiently advanced to have made effigies +of their gods or of their deified rulers, the sculptors no doubt have +endeavoured to express their highest ideal of beauty and grandeur. (67. +Ch. Comte has remarks to this effect in his 'Traité de Législation,' 3rd +ed. 1837, p. 136.) Under this point of view it is well to compare in our +mind the Jupiter or Apollo of the Greeks with the Egyptian or Assyrian +statues; and these with the hideous bas-reliefs on the ruined buildings of +Central America. + +I have met with very few statements opposed to this conclusion. Mr. +Winwood Reade, however, who has had ample opportunities for observation, +not only with the negroes of the West Coast of Africa, but with those of +the interior who have never associated with Europeans, is convinced that +their ideas of beauty are ON THE WHOLE the same as ours; and Dr. Rohlfs +writes to me to the same effect with respect to Bornu and the countries +inhabited by the Pullo tribes. Mr. Reade found that he agreed with the +negroes in their estimation of the beauty of the native girls; and that +their appreciation of the beauty of European women corresponded with ours. +They admire long hair, and use artificial means to make it appear abundant; +they admire also a beard, though themselves very scantily provided. Mr. +Reade feels doubtful what kind of nose is most appreciated; a girl has been +heard to say, "I do not want to marry him, he has got no nose"; and this +shews that a very flat nose is not admired. We should, however, bear in +mind that the depressed, broad noses and projecting jaws of the negroes of +the West Coast are exceptional types with the inhabitants of Africa. +Notwithstanding the foregoing statements, Mr. Reade admits that negroes "do +not like the colour of our skin; they look on blue eyes with aversion, and +they think our noses too long and our lips too thin." He does not think it +probable that negroes would ever prefer the most beautiful European woman, +on the mere grounds of physical admiration, to a good-looking negress. +(68. The 'African Sketch Book,' vol. ii. 1873, pp. 253, 394, 521. The +Fuegians, as I have been informed by a missionary who long resided with +them, consider European women as extremely beautiful; but from what we have +seen of the judgment of the other aborigines of America, I cannot but think +that this must be a mistake, unless indeed the statement refers to the few +Fuegians who have lived for some time with Europeans, and who must consider +us as superior beings. I should add that a most experienced observer, +Capt. Burton, believes that a woman whom we consider beautiful is admired +throughout the world. 'Anthropological Review,' March, 1864, p. 245.) + +The general truth of the principle, long ago insisted on by Humboldt (69. +'Personal Narrative,' Eng. translat. vol. iv. p. 518, and elsewhere. +Mantegazza, in his 'Viaggi e Studi,' strongly insists on this same +principle.), that man admires and often tries to exaggerate whatever +characters nature may have given him, is shewn in many ways. The practice +of beardless races extirpating every trace of a beard, and often all the +hairs on the body affords one illustration. The skull has been greatly +modified during ancient and modern times by many nations; and there can be +little doubt that this has been practised, especially in N. and S. America, +in order to exaggerate some natural and admired peculiarity. Many American +Indians are known to admire a head so extremely flattened as to appear to +us idiotic. The natives on the north-western coast compress the head into +a pointed cone; and it is their constant practice to gather the hair into a +knot on the top of the head, for the sake, as Dr. Wilson remarks, "of +increasing the apparent elevation of the favourite conoid form." The +inhabitants of Arakhan admire a broad, smooth forehead, and in order to +produce it, they fasten a plate of lead on the heads of the new-born +children. On the other hand, "a broad, well-rounded occiput is considered +a great beauty" by the natives of the Fiji Islands. (70. On the skulls of +the American tribes, see Nott and Gliddon, 'Types of Mankind,' 1854, p. +440; Prichard, 'Physical History of Mankind,' vol. i. 3rd ed. p. 321; on +the natives of Arakhan, ibid. vol. iv. p. 537. Wilson, 'Physical +Ethnology,' Smithsonian Institution, 1863, p. 288; on the Fijians, p. 290. +Sir J. Lubbock ('Prehistoric Times,' 2nd ed. 1869, p. 506) gives an +excellent resume on this subject.) + +As with the skull, so with the nose; the ancient Huns during the age of +Attila were accustomed to flatten the noses of their infants with bandages, +"for the sake of exaggerating a natural conformation." With the Tahitians, +to be called LONG-NOSE is considered as an insult, and they compress the +noses and foreheads of their children for the sake of beauty. The same +holds with the Malays of Sumatra, the Hottentots, certain Negroes, and the +natives of Brazil. (71. On the Huns, Godron, 'De l'Espèce,' tom. ii. +1859, p. 300. On the Tahitians, Waitz, 'Anthropology,' Eng. translat. vol. +i. p. 305. Marsden, quoted by Prichard, 'Phys. Hist. of Mankind,' 3rd +edit. vol. v. p. 67. Lawrence, 'Lectures on Physiology,' p. 337.) The +Chinese have by nature unusually small feet (72. This fact was ascertained +in the 'Reise der Novara: Anthropolog. Theil.' Dr. Weisbach, 1867, s. +265.); and it is well known that the women of the upper classes distort +their feet to make them still smaller. Lastly, Humboldt thinks that the +American Indians prefer colouring their bodies with red paint in order to +exaggerate their natural tint; and until recently European women added to +their naturally bright colours by rouge and white cosmetics; but it may be +doubted whether barbarous nations have generally had any such intention in +painting themselves. + +In the fashions of our own dress we see exactly the same principle and the +same desire to carry every point to an extreme; we exhibit, also, the same +spirit of emulation. But the fashions of savages are far more permanent +than ours; and whenever their bodies are artificially modified, this is +necessarily the case. The Arab women of the Upper Nile occupy about three +days in dressing their hair; they never imitate other tribes, "but simply +vie with each other in the superlativeness of their own style." Dr. +Wilson, in speaking of the compressed skulls of various American races, +adds, "such usages are among the least eradicable, and long survive the +shock of revolutions that change dynasties and efface more important +national peculiarities." (73. 'Smithsonian Institution,' 1863, p. 289. +On the fashions of Arab women, Sir S. Baker, 'The Nile Tributaries,' 1867, +p. 121.) The same principle comes into play in the art of breeding; and we +can thus understand, as I have elsewhere explained (74. The 'Variation of +Animals and Plants under Domestication,' vol. i. p. 214; vol. ii. p. 240.), +the wonderful development of the many races of animals and plants, which +have been kept merely for ornament. Fanciers always wish each character to +be somewhat increased; they do not admire a medium standard; they certainly +do not desire any great and abrupt change in the character of their breeds; +they admire solely what they are accustomed to, but they ardently desire to +see each characteristic feature a little more developed. + +The senses of man and of the lower animals seem to be so constituted that +brilliant colours and certain forms, as well as harmonious and rhythmical +sounds, give pleasure and are called beautiful; but why this should be so +we know not. It is certainly not true that there is in the mind of man any +universal standard of beauty with respect to the human body. It is, +however, possible that certain tastes may in the course of time become +inherited, though there is no evidence in favour of this belief: and if +so, each race would possess its own innate ideal standard of beauty. It +has been argued (75. Schaaffhausen, 'Archiv. für Anthropologie,' 1866, s. +164.) that ugliness consists in an approach to the structure of the lower +animals, and no doubt this is partly true with the more civilised nations, +in which intellect is highly appreciated; but this explanation will hardly +apply to all forms of ugliness. The men of each race prefer what they are +accustomed to; they cannot endure any great change; but they like variety, +and admire each characteristic carried to a moderate extreme. (76. Mr. +Bain has collected ('Mental and Moral Science,' 1868, pp. 304-314) about a +dozen more or less different theories of the idea of beauty; but none is +quite the same as that here given.) Men accustomed to a nearly oval face, +to straight and regular features, and to bright colours, admire, as we +Europeans know, these points when strongly developed. On the other hand, +men accustomed to a broad face, with high cheek-bones, a depressed nose, +and a black skin, admire these peculiarities when strongly marked. No +doubt characters of all kinds may be too much developed for beauty. Hence +a perfect beauty, which implies many characters modified in a particular +manner, will be in every race a prodigy. As the great anatomist Bichat +long ago said, if every one were cast in the same mould, there would be no +such thing as beauty. If all our women were to become as beautiful as the +Venus de' Medici, we should for a time be charmed; but we should soon wish +for variety; and as soon as we had obtained variety, we should wish to see +certain characters a little exaggerated beyond the then existing common +standard. + + +CHAPTER XX. + +SECONDARY SEXUAL CHARACTERS OF MAN--continued. + +On the effects of the continued selection of women according to a different +standard of beauty in each race--On the causes which interfere with sexual +selection in civilised and savage nations--Conditions favourable to sexual +selection during primeval times--On the manner of action of sexual +selection with mankind--On the women in savage tribes having some power to +choose their husbands--Absence of hair on the body, and development of the +beard--Colour of the skin--Summary. + +We have seen in the last chapter that with all barbarous races ornaments, +dress, and external appearance are highly valued; and that the men judge of +the beauty of their women by widely different standards. We must next +inquire whether this preference and the consequent selection during many +generations of those women, which appear to the men of each race the most +attractive, has altered the character either of the females alone, or of +both sexes. With mammals the general rule appears to be that characters of +all kinds are inherited equally by the males and females; we might +therefore expect that with mankind any characters gained by the females or +by the males through sexual selection would commonly be transferred to the +offspring of both sexes. If any change has thus been effected, it is +almost certain that the different races would be differently modified, as +each has its own standard of beauty. + +With mankind, especially with savages, many causes interfere with the +action of sexual selection as far as the bodily frame is concerned. +Civilised men are largely attracted by the mental charms of women, by their +wealth, and especially by their social position; for men rarely marry into +a much lower rank. The men who succeed in obtaining the more beautiful +women will not have a better chance of leaving a long line of descendants +than other men with plainer wives, save the few who bequeath their fortunes +according to primogeniture. With respect to the opposite form of +selection, namely, of the more attractive men by the women, although in +civilised nations women have free or almost free choice, which is not the +case with barbarous races, yet their choice is largely influenced by the +social position and wealth of the men; and the success of the latter in +life depends much on their intellectual powers and energy, or on the fruits +of these same powers in their forefathers. No excuse is needed for +treating this subject in some detail; for, as the German philosopher +Schopenhauer remarks, "the final aim of all love intrigues, be they comic +or tragic, is really of more importance than all other ends in human life. +What it all turns upon is nothing less than the composition of the next +generation...It is not the weal or woe of any one individual, but that of +the human race to come, which is here at stake." (1. 'Schopenhauer and +Darwinism,' in 'Journal of Anthropology,' Jan. 1871, p. 323. + +There is, however, reason to believe that in certain civilised and semi- +civilised nations sexual selection has effected something in modifying the +bodily frame of some of the members. Many persons are convinced, as it +appears to me with justice, that our aristocracy, including under this term +all wealthy families in which primogeniture has long prevailed, from having +chosen during many generations from all classes the more beautiful women as +their wives, have become handsomer, according to the European standard, +than the middle classes; yet the middle classes are placed under equally +favourable conditions of life for the perfect development of the body. +Cook remarks that the superiority in personal appearance "which is +observable in the erees or nobles in all the other islands (of the Pacific) +is found in the Sandwich Islands"; but this may be chiefly due to their +better food and manner of life. + +The old traveller Chardin, in describing the Persians, says their "blood is +now highly refined by frequent intermixtures with the Georgians and +Circassians, two nations which surpass all the world in personal beauty. +There is hardly a man of rank in Persia who is not born of a Georgian or +Circassian mother." He adds that they inherit their beauty, "not from +their ancestors, for without the above mixture, the men of rank in Persia, +who are descendants of the Tartars, would be extremely ugly." (2. These +quotations are taken from Lawrence ('Lectures on Physiology,' etc., 1822, +p. 393), who attributes the beauty of the upper classes in England to the +men having long selected the more beautiful women.) Here is a more curious +case; the priestesses who attended the temple of Venus Erycina at San- +Giuliano in Sicily, were selected for their beauty out of the whole of +Greece; they were not vestal virgins, and Quatrefages (3. 'Anthropologie,' +'Revue des Cours Scientifiques,' Oct. 1868, p. 721.), who states the +foregoing fact, says that the women of San-Giuliano are now famous as the +most beautiful in the island, and are sought by artists as models. But it +is obvious that the evidence in all the above cases is doubtful. + +The following case, though relating to savages, is well worth giving for +its curiosity. Mr. Winwood Reade informs me that the Jollofs, a tribe of +negroes on the west coast of Africa, "are remarkable for their uniformly +fine appearance." A friend of his asked one of these men, "How is it that +every one whom I meet is so fine looking, not only your men but your +women?" The Jollof answered, "It is very easily explained: it has always +been our custom to pick out our worst-looking slaves and to sell them." It +need hardly be added that with all savages, female slaves serve as +concubines. That this negro should have attributed, whether rightly or +wrongly, the fine appearance of his tribe to the long-continued elimination +of the ugly women is not so surprising as it may at first appear; for I +have elsewhere shewn (4. 'Variation of Animals and Plants under +Domestication,' vol. i. p. 207.) that negroes fully appreciate the +importance of selection in the breeding of their domestic animals, and I +could give from Mr. Reade additional evidence on this head. + +THE CAUSES WHICH PREVENT OR CHECK THE ACTION OF SEXUAL SELECTION WITH +SAVAGES. + +The chief causes are, first, so-called communal marriages or promiscuous +intercourse; secondly, the consequences of female infanticide; thirdly, +early betrothals; and lastly, the low estimation in which women are held, +as mere slaves. These four points must be considered in some detail. + +It is obvious that as long as the pairing of man, or of any other animal, +is left to mere chance, with no choice exerted by either sex, there can be +no sexual selection; and no effect will be produced on the offspring by +certain individuals having had an advantage over others in their courtship. +Now it is asserted that there exist at the present day tribes which +practise what Sir J. Lubbock by courtesy calls communal marriages; that is, +all the men and women in the tribe are husbands and wives to one another. +The licentiousness of many savages is no doubt astonishing, but it seems to +me that more evidence is requisite, before we fully admit that their +intercourse is in any case promiscuous. Nevertheless all those who have +most closely studied the subject (5. Sir J. Lubbock, 'The Origin of +Civilisation,' 1870, chap. iii. especially pp. 60-67. Mr. M'Lennan, in his +extremely valuable work on 'Primitive Marriage,' 1865, p. 163, speaks of +the union of the sexes "in the earliest times as loose, transitory, and in +some degree promiscuous." Mr. M'Lennan and Sir J. Lubbock have collected +much evidence on the extreme licentiousness of savages at the present time. +Mr. L.H. Morgan, in his interesting memoir of the classificatory system of +relationship. ('Proceedings of the American Academy of Sciences,' vol. +vii. Feb. 1868, p. 475), concludes that polygamy and all forms of marriage +during primeval times were essentially unknown. It appears also, from Sir +J. Lubbock's work, that Bachofen likewise believes that communal +intercourse originally prevailed.), and whose judgment is worth much more +than mine, believe that communal marriage (this expression being variously +guarded) was the original and universal form throughout the world, +including therein the intermarriage of brothers and sisters. The late Sir +A. Smith, who had travelled widely in S. Africa, and knew much about the +habits of savages there and elsewhere, expressed to me the strongest +opinion that no race exists in which woman is considered as the property of +the community. I believe that his judgment was largely determined by what +is implied by the term marriage. Throughout the following discussion I use +the term in the same sense as when naturalists speak of animals as +monogamous, meaning thereby that the male is accepted by or chooses a +single female, and lives with her either during the breeding-season or for +the whole year, keeping possession of her by the law of might; or, as when +they speak of a polygamous species, meaning that the male lives with +several females. This kind of marriage is all that concerns us here, as it +suffices for the work of sexual selection. But I know that some of the +writers above referred to imply by the term marriage a recognised right +protected by the tribe. + +The indirect evidence in favour of the belief of the former prevalence of +communal marriages is strong, and rests chiefly on the terms of +relationship which are employed between the members of the same tribe, +implying a connection with the tribe, and not with either parent. But the +subject is too large and complex for even an abstract to be here given, and +I will confine myself to a few remarks. It is evident in the case of such +marriages, or where the marriage tie is very loose, that the relationship +of the child to its father cannot be known. But it seems almost incredible +that the relationship of the child to its mother should ever be completely +ignored, especially as the women in most savage tribes nurse their infants +for a long time. Accordingly, in many cases the lines of descent are +traced through the mother alone, to the exclusion of the father. But in +other cases the terms employed express a connection with the tribe alone, +to the exclusion even of the mother. It seems possible that the connection +between the related members of the same barbarous tribe, exposed to all +sorts of danger, might be so much more important, owing to the need of +mutual protection and aid, than that between the mother and her child, as +to lead to the sole use of terms expressive of the former relationships; +but Mr. Morgan is convinced that this view is by no means sufficient. + +The terms of relationship used in different parts of the world may be +divided, according to the author just quoted, into two great classes, the +classificatory and descriptive, the latter being employed by us. It is the +classificatory system which so strongly leads to the belief that communal +and other extremely loose forms of marriage were originally universal. But +as far as I can see, there is no necessity on this ground for believing in +absolutely promiscuous intercourse; and I am glad to find that this is Sir +J. Lubbock's view. Men and women, like many of the lower animals, might +formerly have entered into strict though temporary unions for each birth, +and in this case nearly as much confusion would have arisen in the terms of +relationship as in the case of promiscuous intercourse. As far as sexual +selection is concerned, all that is required is that choice should be +exerted before the parents unite, and it signifies little whether the +unions last for life or only for a season. + +Besides the evidence derived from the terms of relationship, other lines of +reasoning indicate the former wide prevalence of communal marriage. Sir J. +Lubbock accounts for the strange and widely-extended habit of exogamy--that +is, the men of one tribe taking wives from a distinct tribe,--by communism +having been the original form of intercourse; so that a man never obtained +a wife for himself unless he captured her from a neighbouring and hostile +tribe, and then she would naturally have become his sole and valuable +property. Thus the practice of capturing wives might have arisen; and from +the honour so gained it might ultimately have become the universal habit. +According to Sir J. Lubbock (6. 'Address to British Association On the +Social and Religious Condition of the Lower Races of Man,' 1870, p. 20.), +we can also thus understand "the necessity of expiation for marriage as an +infringement of tribal rites, since according to old ideas, a man had no +right to appropriate to himself that which belonged to the whole tribe." +Sir J. Lubbock further gives a curious body of facts shewing that in old +times high honour was bestowed on women who were utterly licentious; and +this, as he explains, is intelligible, if we admit that promiscuous +intercourse was the aboriginal, and therefore long revered custom of the +tribe. (7. 'Origin of Civilisation,' 1870, p. 86. In the several works +above quoted, there will be found copious evidence on relationship through +the females alone, or with the tribe alone.) + +Although the manner of development of the marriage tie is an obscure +subject, as we may infer from the divergent opinions on several points +between the three authors who have studied it most closely, namely, Mr. +Morgan, Mr. M'Lennan, and Sir J. Lubbock, yet from the foregoing and +several other lines of evidence it seems probable (8. Mr. C. Staniland +Wake argues strongly ('Anthropologia,' March, 1874, p. 197) against the +views held by these three writers on the former prevalence of almost +promiscuous intercourse; and he thinks that the classificatory system of +relationship can be otherwise explained.) that the habit of marriage, in +any strict sense of the word, has been gradually developed; and that almost +promiscuous or very loose intercourse was once extremely common throughout +the world. Nevertheless, from the strength of the feeling of jealousy all +through the animal kingdom, as well as from the analogy of the lower +animals, more particularly of those which come nearest to man, I cannot +believe that absolutely promiscuous intercourse prevailed in times past, +shortly before man attained to his present rank in the zoological scale. +Man, as I have attempted to shew, is certainly descended from some ape-like +creature. With the existing Quadrumana, as far as their habits are known, +the males of some species are monogamous, but live during only a part of +the year with the females: of this the orang seems to afford an instance. +Several kinds, for example some of the Indian and American monkeys, are +strictly monogamous, and associate all the year round with their wives. +Others are polygamous, for example the gorilla and several American +species, and each family lives separate. Even when this occurs, the +families inhabiting the same district are probably somewhat social; the +chimpanzee, for instance, is occasionally met with in large bands. Again, +other species are polygamous, but several males, each with his own females, +live associated in a body, as with several species of baboons. (9. Brehm +('Thierleben,' B. i. p. 77) says Cynocephalus hamadryas lives in great +troops containing twice as many adult females as adult males. See Rengger +on American polygamous species, and Owen ('Anatomy of Vertebrates,' vol. +iii. p. 746) on American monogamous species. Other references might be +added.) We may indeed conclude from what we know of the jealousy of all +male quadrupeds, armed, as many of them are, with special weapons for +battling with their rivals, that promiscuous intercourse in a state of +nature is extremely improbable. The pairing may not last for life, but +only for each birth; yet if the males which are the strongest and best able +to defend or otherwise assist their females and young, were to select the +more attractive females, this would suffice for sexual selection. + +Therefore, looking far enough back in the stream of time, and judging from +the social habits of man as he now exists, the most probable view is that +he aboriginally lived in small communities, each with a single wife, or if +powerful with several, whom he jealously guarded against all other men. Or +he may not have been a social animal, and yet have lived with several +wives, like the gorilla; for all the natives "agree that but one adult male +is seen in a band; when the young male grows up, a contest takes place for +mastery, and the strongest, by killing and driving out the others, +establishes himself as the head of the community." (10. Dr. Savage, in +'Boston Journal of Natural History,' vol. v. 1845-47, p. 423.) The younger +males, being thus expelled and wandering about, would, when at last +successful in finding a partner, prevent too close interbreeding within the +limits of the same family. + +Although savages are now extremely licentious, and although communal +marriages may formerly have largely prevailed, yet many tribes practise +some form of marriage, but of a far more lax nature than that of civilised +nations. Polygamy, as just stated, is almost universally followed by the +leading men in every tribe. Nevertheless there are tribes, standing almost +at the bottom of the scale, which are strictly monogamous. This is the +case with the Veddahs of Ceylon: they have a saying, according to Sir J. +Lubbock (11. 'Prehistoric Times,' 1869, p. 424.), "that death alone can +separate husband and wife." An intelligent Kandyan chief, of course a +polygamist, "was perfectly scandalised at the utter barbarism of living +with only one wife, and never parting until separated by death." It was, +he said, "just like the Wanderoo monkeys." Whether savages who now enter +into some form of marriage, either polygamous or monogamous, have retained +this habit from primeval times, or whether they have returned to some form +of marriage, after passing through a stage of promiscuous intercourse, I +will not pretend to conjecture. + +INFANTICIDE. + +This practice is now very common throughout the world, and there is reason +to believe that it prevailed much more extensively during former times. +(12. Mr. M'Lennan, 'Primitive Marriage,' 1865. See especially on exogamy +and infanticide, pp. 130, 138, 165.) Barbarians find it difficult to +support themselves and their children, and it is a simple plan to kill +their infants. In South America some tribes, according to Azara, formerly +destroyed so many infants of both sexes that they were on the point of +extinction. In the Polynesian Islands women have been known to kill from +four or five, to even ten of their children; and Ellis could not find a +single woman who had not killed at least one. In a village on the eastern +frontier of India Colonel MacCulloch found not a single female child. +Wherever infanticide (13. Dr. Gerland ('Ueber das Aussterben der +Naturvölker,' 1868) has collected much information on infanticide, see +especially ss. 27, 51, 54. Azara ('Voyages,' etc., tom. ii. pp. 94, 116) +enters in detail on the motives. See also M'Lennan (ibid. p. 139) for +cases in India. In the former reprints of the 2nd edition of this book an +incorrect quotation from Sir G. Grey was unfortunately given in the above +passage and has now been removed from the text.) prevails the struggle for +existence will be in so far less severe, and all the members of the tribe +will have an almost equally good chance of rearing their few surviving +children. In most cases a larger number of female than of male infants are +destroyed, for it is obvious that the latter are of more value to the +tribe, as they will, when grown up, aid in defending it, and can support +themselves. But the trouble experienced by the women in rearing children, +their consequent loss of beauty, the higher estimation set on them when +few, and their happier fate, are assigned by the women themselves, and by +various observers, as additional motives for infanticide. + +When, owing to female infanticide, the women of a tribe were few, the habit +of capturing wives from neighbouring tribes would naturally arise. Sir J. +Lubbock, however, as we have seen, attributes the practice in chief part to +the former existence of communal marriage, and to the men having +consequently captured women from other tribes to hold as their sole +property. Additional causes might be assigned, such as the communities +being very small, in which case, marriageable women would often be +deficient. That the habit was most extensively practised during former +times, even by the ancestors of civilised nations, is clearly shewn by the +preservation of many curious customs and ceremonies, of which Mr. M'Lennan +has given an interesting account. In our own marriages the "best man" +seems originally to have been the chief abettor of the bridegroom in the +act of capture. Now as long as men habitually procured their wives through +violence and craft, they would have been glad to seize on any woman, and +would not have selected the more attractive ones. But as soon as the +practice of procuring wives from a distinct tribe was effected through +barter, as now occurs in many places, the more attractive women would +generally have been purchased. The incessant crossing, however, between +tribe and tribe, which necessarily follows from any form of this habit, +would tend to keep all the people inhabiting the same country nearly +uniform in character; and this would interfere with the power of sexual +selection in differentiating the tribes. + +The scarcity of women, consequent on female infanticide, leads, also, to +another practice, that of polyandry, still common in several parts of the +world, and which formerly, as Mr. M'Lennan believes, prevailed almost +universally: but this latter conclusion is doubted by Mr. Morgan and Sir +J. Lubbock. (14. 'Primitive Marriage,' p. 208; Sir J. Lubbock, 'Origin of +Civilisation,' p. 100. See also Mr. Morgan, loc. cit., on the former +prevalence of polyandry.) Whenever two or more men are compelled to marry +one woman, it is certain that all the women of the tribe will get married, +and there will be no selection by the men of the more attractive women. +But under these circumstances the women no doubt will have the power of +choice, and will prefer the more attractive men. Azara, for instance, +describes how carefully a Guana woman bargains for all sorts of privileges, +before accepting some one or more husbands; and the men in consequence take +unusual care of their personal appearance. So amongst the Todas of India, +who practise polyandry, the girls can accept or refuse any man. (15. +Azara, 'Voyages,' etc., tom. ii. pp. 92-95; Colonel Marshall, 'Amongst the +Todas,' p. 212.) A very ugly man in these cases would perhaps altogether +fail in getting a wife, or get one later in life; but the handsomer men, +although more successful in obtaining wives, would not, as far as we can +see, leave more offspring to inherit their beauty than the less handsome +husbands of the same women. + +EARLY BETROTHALS AND SLAVERY OF WOMEN. + +With many savages it is the custom to betroth the females whilst mere +infants; and this would effectually prevent preference being exerted on +either side according to personal appearance. But it would not prevent the +more attractive women from being afterwards stolen or taken by force from +their husbands by the more powerful men; and this often happens in +Australia, America, and elsewhere. The same consequences with reference to +sexual selection would to a certain extent follow, when women are valued +almost solely as slaves or beasts of burden, as is the case with many +savages. The men, however, at all times would prefer the handsomest slaves +according to their standard of beauty. + +We thus see that several customs prevail with savages which must greatly +interfere with, or completely stop, the action of sexual selection. On the +other hand, the conditions of life to which savages are exposed, and some +of their habits, are favourable to natural selection; and this comes into +play at the same time with sexual selection. Savages are known to suffer +severely from recurrent famines; they do not increase their food by +artificial means; they rarely refrain from marriage (16. Burchell says +('Travels in S. Africa,' vol. ii. 1824, p. 58), that among the wild nations +of Southern Africa, neither men nor women ever pass their lives in a state +of celibacy. Azara ('Voyages dans l'Amérique Merid.' tom. ii. 1809, p. 21) +makes precisely the same remark in regard to the wild Indians of South +America.), and generally marry whilst young. Consequently they must be +subjected to occasional hard struggles for existence, and the favoured +individuals will alone survive. + +At a very early period, before man attained to his present rank in the +scale, many of his conditions would be different from what now obtains +amongst savages. Judging from the analogy of the lower animals, he would +then either live with a single female, or be a polygamist. The most +powerful and able males would succeed best in obtaining attractive females. +They would also succeed best in the general struggle for life, and in +defending their females, as well as their offspring, from enemies of all +kinds. At this early period the ancestors of man would not be sufficiently +advanced in intellect to look forward to distant contingencies; they would +not foresee that the rearing of all their children, especially their female +children, would make the struggle for life severer for the tribe. They +would be governed more by their instincts and less by their reason than are +savages at the present day. They would not at that period have partially +lost one of the strongest of all instincts, common to all the lower +animals, namely the love of their young offspring; and consequently they +would not have practised female infanticide. Women would not have been +thus rendered scarce, and polyandry would not have been practised; for +hardly any other cause, except the scarcity of women seems sufficient to +break down the natural and widely prevalent feeling of jealousy, and the +desire of each male to possess a female for himself. Polyandry would be a +natural stepping-stone to communal marriages or almost promiscuous +intercourse; though the best authorities believe that this latter habit +preceded polyandry. During primordial times there would be no early +betrothals, for this implies foresight. Nor would women be valued merely +as useful slaves or beasts of burthen. Both sexes, if the females as well +as the males were permitted to exert any choice, would choose their +partners not for mental charms, or property, or social position, but almost +solely from external appearance. All the adults would marry or pair, and +all the offspring, as far as that was possible, would be reared; so that +the struggle for existence would be periodically excessively severe. Thus +during these times all the conditions for sexual selection would have been +more favourable than at a later period, when man had advanced in his +intellectual powers but had retrograded in his instincts. Therefore, +whatever influence sexual selection may have had in producing the +differences between the races of man, and between man and the higher +Quadrumana, this influence would have been more powerful at a remote period +than at the present day, though probably not yet wholly lost. + +THE MANNER OF ACTION OF SEXUAL SELECTION WITH MANKIND. + +With primeval man under the favourable conditions just stated, and with +those savages who at the present time enter into any marriage tie, sexual +selection has probably acted in the following manner, subject to greater or +less interference from female infanticide, early betrothals, etc. The +strongest and most vigorous men--those who could best defend and hunt for +their families, who were provided with the best weapons and possessed the +most property, such as a large number of dogs or other animals,--would +succeed in rearing a greater average number of offspring than the weaker +and poorer members of the same tribes. There can, also, be no doubt that +such men would generally be able to select the more attractive women. At +present the chiefs of nearly every tribe throughout the world succeed in +obtaining more than one wife. I hear from Mr. Mantell that, until +recently, almost every girl in New Zealand who was pretty, or promised to +be pretty, was tapu to some chief. With the Kafirs, as Mr. C. Hamilton +states (17. 'Anthropological Review,' Jan. 1870, p. xvi.), "the chiefs +generally have the pick of the women for many miles round, and are most +persevering in establishing or confirming their privilege." We have seen +that each race has its own style of beauty, and we know that it is natural +to man to admire each characteristic point in his domestic animals, dress, +ornaments, and personal appearance, when carried a little beyond the +average. If then the several foregoing propositions be admitted, and I +cannot see that they are doubtful, it would be an inexplicable circumstance +if the selection of the more attractive women by the more powerful men of +each tribe, who would rear on an average a greater number of children, did +not after the lapse of many generations somewhat modify the character of +the tribe. + +When a foreign breed of our domestic animals is introduced into a new +country, or when a native breed is long and carefully attended to, either +for use or ornament, it is found after several generations to have +undergone a greater or less amount of change whenever the means of +comparison exist. This follows from unconscious selection during a long +series of generations--that is, the preservation of the most approved +individuals--without any wish or expectation of such a result on the part +of the breeder. So again, if during many years two careful breeders rear +animals of the same family, and do not compare them together or with a +common standard, the animals are found to have become, to the surprise of +their owners, slightly different. (18. The 'Variation of Animals and +Plants under Domestication,' vol. ii. pp. 210-217.) Each breeder has +impressed, as von Nathusius well expresses it, the character of his own +mind--his own taste and judgment--on his animals. What reason, then, can +be assigned why similar results should not follow from the long-continued +selection of the most admired women by those men of each tribe who were +able to rear the greatest number of children? This would be unconscious +selection, for an effect would be produced, independently of any wish or +expectation on the part of the men who preferred certain women to others. + +Let us suppose the members of a tribe, practising some form of marriage, to +spread over an unoccupied continent, they would soon split up into distinct +hordes, separated from each other by various barriers, and still more +effectually by the incessant wars between all barbarous nations. The +hordes would thus be exposed to slightly different conditions and habits of +life, and would sooner or later come to differ in some small degree. As +soon as this occurred, each isolated tribe would form for itself a slightly +different standard of beauty (19. An ingenious writer argues, from a +comparison of the pictures of Raphael, Rubens, and modern French artists, +that the idea of beauty is not absolutely the same even throughout Europe: +see the 'Lives of Haydn and Mozart,' by Bombet (otherwise M. Beyle), +English translation, p. 278.); and then unconscious selection would come +into action through the more powerful and leading men preferring certain +women to others. Thus the differences between the tribes, at first very +slight, would gradually and inevitably be more or less increased. + +With animals in a state of nature, many characters proper to the males, +such as size, strength, special weapons, courage and pugnacity, have been +acquired through the law of battle. The semi-human progenitors of man, +like their allies the Quadrumana, will almost certainly have been thus +modified; and, as savages still fight for the possession of their women, a +similar process of selection has probably gone on in a greater or less +degree to the present day. Other characters proper to the males of the +lower animals, such as bright colours and various ornaments, have been +acquired by the more attractive males having been preferred by the females. +There are, however, exceptional cases in which the males are the selectors, +instead of having been the selected. We recognise such cases by the +females being more highly ornamented than the males,--their ornamental +characters having been transmitted exclusively or chiefly to their female +offspring. One such case has been described in the order to which man +belongs, that of the Rhesus monkey. + +Man is more powerful in body and mind than woman, and in the savage state +he keeps her in a far more abject state of bondage than does the male of +any other animal; therefore it is not surprising that he should have gained +the power of selection. Women are everywhere conscious of the value of +their own beauty; and when they have the means, they take more delight in +decorating themselves with all sorts of ornaments than do men. They borrow +the plumes of male birds, with which nature has decked this sex, in order +to charm the females. As women have long been selected for beauty, it is +not surprising that some of their successive variations should have been +transmitted exclusively to the same sex; consequently that they should have +transmitted beauty in a somewhat higher degree to their female than to +their male offspring, and thus have become more beautiful, according to +general opinion, than men. Women, however, certainly transmit most of +their characters, including some beauty, to their offspring of both sexes; +so that the continued preference by the men of each race for the more +attractive women, according to their standard of taste, will have tended to +modify in the same manner all the individuals of both sexes belonging to +the race. + +With respect to the other form of sexual selection (which with the lower +animals is much the more common), namely, when the females are the +selectors, and accept only those males which excite or charm them most, we +have reason to believe that it formerly acted on our progenitors. Man in +all probability owes his beard, and perhaps some other characters, to +inheritance from an ancient progenitor who thus gained his ornaments. But +this form of selection may have occasionally acted during later times; for +in utterly barbarous tribes the women have more power in choosing, +rejecting, and tempting their lovers, or of afterwards changing their +husbands, than might have been expected. As this is a point of some +importance, I will give in detail such evidence as I have been able to +collect. + +Hearne describes how a woman in one of the tribes of Arctic America +repeatedly ran away from her husband and joined her lover; and with the +Charruas of S. America, according to Azara, divorce is quite optional. +Amongst the Abipones, a man on choosing a wife bargains with the parents +about the price. But "it frequently happens that the girl rescinds what +has been agreed upon between the parents and the bridegroom, obstinately +rejecting the very mention of marriage." She often runs away, hides +herself, and thus eludes the bridegroom. Captain Musters who lived with +the Patagonians, says that their marriages are always settled by +inclination; "if the parents make a match contrary to the daughter's will, +she refuses and is never compelled to comply." In Tierra del Fuego a young +man first obtains the consent of the parents by doing them some service, +and then he attempts to carry off the girl; "but if she is unwilling, she +hides herself in the woods until her admirer is heartily tired of looking +for her, and gives up the pursuit; but this seldom happens." In the Fiji +Islands the man seizes on the woman whom he wishes for his wife by actual +or pretended force; but "on reaching the home of her abductor, should she +not approve of the match, she runs to some one who can protect her; if, +however, she is satisfied, the matter is settled forthwith." With the +Kalmucks there is a regular race between the bride and bridegroom, the +former having a fair start; and Clarke "was assured that no instance occurs +of a girl being caught, unless she has a partiality to the pursuer." +Amongst the wild tribes of the Malay Archipelago there is also a racing +match; and it appears from M. Bourien's account, as Sir J. Lubbock remarks, +that "the race, 'is not to the swift, nor the battle to the strong,' but to +the young man who has the good fortune to please his intended bride." A +similar custom, with the same result, prevails with the Koraks of North- +Eastern Asia. + +Turning to Africa: the Kafirs buy their wives, and girls are severely +beaten by their fathers if they will not accept a chosen husband; but it is +manifest from many facts given by the Rev. Mr. Shooter, that they have +considerable power of choice. Thus very ugly, though rich men, have been +known to fail in getting wives. The girls, before consenting to be +betrothed, compel the men to shew themselves off first in front and then +behind, and "exhibit their paces." They have been known to propose to a +man, and they not rarely run away with a favoured lover. So again, Mr. +Leslie, who was intimately acquainted with the Kafirs, says, "it is a +mistake to imagine that a girl is sold by her father in the same manner, +and with the same authority, with which he would dispose of a cow." +Amongst the degraded Bushmen of S. Africa, "when a girl has grown up to +womanhood without having been betrothed, which, however, does not often +happen, her lover must gain her approbation, as well as that of the +parents." (20. Azara, 'Voyages,' etc., tom. ii. p. 23. Dobrizhoffer, 'An +Account of the Abipones,' vol. ii. 1822, p. 207. Capt. Musters, in 'Proc. +R. Geograph. Soc.' vol. xv. p. 47. Williams on the Fiji Islanders, as +quoted by Lubbock, 'Origin of Civilisation,' 1870, p. 79. On the Fuegians, +King and Fitzroy, 'Voyages of the "Adventure" and "Beagle,"' vol. ii. 1839, +p. 182. On the Kalmucks, quoted by M'Lennan, 'Primitive Marriage,' 1865, +p. 32. On the Malays, Lubbock, ibid. p. 76. The Rev. J. Shooter, 'On the +Kafirs of Natal,' 1857, pp. 52-60. Mr. D. Leslie, 'Kafir Character and +Customs,' 1871, p. 4. On the Bush-men, Burchell, 'Travels in S. Africa,' +ii. 1824, p. 59. On the Koraks by McKennan, as quoted by Mr. Wake, in +'Anthropologia,' Oct. 1873, p. 75.) Mr. Winwood Reade made inquiries for +me with respect to the negroes of Western Africa, and he informs me that +"the women, at least among the more intelligent Pagan tribes, have no +difficulty in getting the husbands whom they may desire, although it is +considered unwomanly to ask a man to marry them. They are quite capable of +falling in love, and of forming tender, passionate, and faithful +attachments." Additional cases could be given. + +We thus see that with savages the women are not in quite so abject a state +in relation to marriage as has often been supposed. They can tempt the men +whom they prefer, and can sometimes reject those whom they dislike, either +before or after marriage. Preference on the part of the women, steadily +acting in any one direction, would ultimately affect the character of the +tribe; for the women would generally choose not merely the handsomest men, +according to their standard of taste, but those who were at the same time +best able to defend and support them. Such well-endowed pairs would +commonly rear a larger number of offspring than the less favoured. The +same result would obviously follow in a still more marked manner if there +was selection on both sides; that is, if the more attractive, and at the +same time more powerful men were to prefer, and were preferred by, the more +attractive women. And this double form of selection seems actually to have +occurred, especially during the earlier periods of our long history. + +We will now examine a little more closely some of the characters which +distinguish the several races of man from one another and from the lower +animals, namely, the greater or less deficiency of hair on the body, and +the colour of the skin. We need say nothing about the great diversity in +the shape of the features and of the skull between the different races, as +we have seen in the last chapter how different is the standard of beauty in +these respects. These characters will therefore probably have been acted +on through sexual selection; but we have no means of judging whether they +have been acted on chiefly from the male or female side. The musical +faculties of man have likewise been already discussed. + +ABSENCE OF HAIR ON THE BODY, AND ITS DEVELOPMENT ON THE FACE AND HEAD. + +From the presence of the woolly hair or lanugo on the human foetus, and of +rudimentary hairs scattered over the body during maturity, we may infer +that man is descended from some animal which was born hairy and remained so +during life. The loss of hair is an inconvenience and probably an injury +to man, even in a hot climate, for he is thus exposed to the scorching of +the sun, and to sudden chills, especially during wet weather. As Mr. +Wallace remarks, the natives in all countries are glad to protect their +naked backs and shoulders with some slight covering. No one supposes that +the nakedness of the skin is any direct advantage to man; his body +therefore cannot have been divested of hair through natural selection. +(21. 'Contributions to the Theory of Natural Selection,' 1870, p. 346. +Mr. Wallace believes (p. 350) "that some intelligent power has guided or +determined the development of man"; and he considers the hairless condition +of the skin as coming under this head. The Rev. T.R. Stebbing, in +commenting on this view ('Transactions of Devonshire Association for +Science,' 1870) remarks, that had Mr. Wallace "employed his usual ingenuity +on the question of man's hairless skin, he might have seen the possibility +of its selection through its superior beauty or the health attaching to +superior cleanliness.") Nor, as shewn in a former chapter, have we any +evidence that this can be due to the direct action of climate, or that it +is the result of correlated development. + +The absence of hair on the body is to a certain extent a secondary sexual +character; for in all parts of the world women are less hairy than men. +Therefore we may reasonably suspect that this character has been gained +through sexual selection. We know that the faces of several species of +monkeys, and large surfaces at the posterior end of the body of other +species, have been denuded of hair; and this we may safely attribute to +sexual selection, for these surfaces are not only vividly coloured, but +sometimes, as with the male mandrill and female rhesus, much more vividly +in the one sex than in the other, especially during the breeding-season. I +am informed by Mr. Bartlett that, as these animals gradually reach +maturity, the naked surfaces grow larger compared with the size of their +bodies. The hair, however, appears to have been removed, not for the sake +of nudity, but that the colour of the skin may be more fully displayed. So +again with many birds, it appears as if the head and neck had been divested +of feathers through sexual selection, to exhibit the brightly-coloured +skin. + +As the body in woman is less hairy than in man, and as this character is +common to all races, we may conclude that it was our female semi-human +ancestors who were first divested of hair, and that this occurred at an +extremely remote period before the several races had diverged from a common +stock. Whilst our female ancestors were gradually acquiring this new +character of nudity, they must have transmitted it almost equally to their +offspring of both sexes whilst young; so that its transmission, as with the +ornaments of many mammals and birds, has not been limited either by sex or +age. There is nothing surprising in a partial loss of hair having been +esteemed as an ornament by our ape-like progenitors, for we have seen that +innumerable strange characters have been thus esteemed by animals of all +kinds, and have consequently been gained through sexual selection. Nor is +it surprising that a slightly injurious character should have been thus +acquired; for we know that this is the case with the plumes of certain +birds, and with the horns of certain stags. + +The females of some of the anthropoid apes, as stated in a former chapter, +are somewhat less hairy on the under surface than the males; and here we +have what might have afforded a commencement for the process of denudation. +With respect to the completion of the process through sexual selection, it +is well to bear in mind the New Zealand proverb, "There is no woman for a +hairy man." All who have seen photographs of the Siamese hairy family will +admit how ludicrously hideous is the opposite extreme of excessive +hairiness. And the king of Siam had to bribe a man to marry the first +hairy woman in the family; and she transmitted this character to her young +offspring of both sexes. (22. The 'Variation of Animals and Plants under +Domestication,' vol. ii. 1868, p. 237.) + +Some races are much more hairy than others, especially the males; but it +must not be assumed that the more hairy races, such as the European, have +retained their primordial condition more completely than the naked races, +such as the Kalmucks or Americans. It is more probable that the hairiness +of the former is due to partial reversion; for characters which have been +at some former period long inherited are always apt to return. We have +seen that idiots are often very hairy, and they are apt to revert in other +characters to a lower animal type. It does not appear that a cold climate +has been influential in leading to this kind of reversion; excepting +perhaps with the negroes, who have been reared during several generations +in the United States (23. 'Investigations into Military and +Anthropological Statistics of American Soldiers,' by B.A. Gould, 1869, p. +568:--Observations were carefully made on the hairiness of 2129 black and +coloured soldiers, whilst they were bathing; and by looking to the +published table, "it is manifest at a glance that there is but little, if +any, difference between the white and the black races in this respect." It +is, however, certain that negroes in their native and much hotter land of +Africa, have remarkably smooth bodies. It should be particularly observed, +that both pure blacks and mulattoes were included in the above enumeration; +and this is an unfortunate circumstance, as in accordance with a principle, +the truth of which I have elsewhere proved, crossed races of man would be +eminently liable to revert to the primordial hairy character of their early +ape-like progenitors.), and possibly with the Ainos, who inhabit the +northern islands of the Japan archipelago. But the laws of inheritance are +so complex that we can seldom understand their action. If the greater +hairiness of certain races be the result of reversion, unchecked by any +form of selection, its extreme variability, even within the limits of the +same race, ceases to be remarkable. (24. Hardly any view advanced in this +work has met with so much disfavour (see for instance, Sprengel, 'Die +Fortschritte des Darwinismus,' 1874, p. 80) as the above explanation of the +loss of hair in mankind through sexual selection; but none of the opposed +arguments seem to me of much weight, in comparison with the facts shewing +that the nudity of the skin is to a certain extent a secondary sexual +character in man and in some of the Quadrumana.) + +With respect to the beard in man, if we turn to our best guide, the +Quadrumana, we find beards equally developed in both sexes of many species, +but in some, either confined to the males, or more developed in them than +in the females. From this fact and from the curious arrangement, as well +as the bright colours of the hair about the heads of many monkeys, it is +highly probable, as before explained, that the males first acquired their +beards through sexual selection as an ornament, transmitting them in most +cases, equally or nearly so, to their offspring of both sexes. We know +from Eschricht (25. 'Ueber die Richtung der Haare am Menschlichen Körper,' +in Müller's 'Archiv. für Anat. und Phys.' 1837, s. 40.) that with mankind +the female as well as the male foetus is furnished with much hair on the +face, especially round the mouth; and this indicates that we are descended +from progenitors of whom both sexes were bearded. It appears therefore at +first sight probable that man has retained his beard from a very early +period, whilst woman lost her beard at the same time that her body became +almost completely divested of hair. Even the colour of our beards seems to +have been inherited from an ape-like progenitor; for when there is any +difference in tint between the hair of the head and the beard, the latter +is lighter coloured in all monkeys and in man. In those Quadrumana in +which the male has a larger beard than that of the female, it is fully +developed only at maturity, just as with mankind; and it is possible that +only the later stages of development have been retained by man. In +opposition to this view of the retention of the beard from an early period +is the fact of its great variability in different races, and even within +the same race; for this indicates reversion,--long lost characters being +very apt to vary on re-appearance. + +Nor must we overlook the part which sexual selection may have played in +later times; for we know that with savages the men of the beardless races +take infinite pains in eradicating every hair from their faces as something +odious, whilst the men of the bearded races feel the greatest pride in +their beards. The women, no doubt, participate in these feelings, and if +so sexual selection can hardly have failed to have effected something in +the course of later times. It is also possible that the long-continued +habit of eradicating the hair may have produced an inherited effect. Dr. +Brown-Sequard has shewn that if certain animals are operated on in a +particular manner, their offspring are affected. Further evidence could be +given of the inheritance of the effects of mutilations; but a fact lately +ascertained by Mr. Salvin (26. On the tail-feathers of Motmots, +'Proceedings of the Zoological Society,' 1873, p. 429.) has a more direct +bearing on the present question; for he has shewn that the motmots, which +are known habitually to bite off the barbs of the two central tail- +feathers, have the barbs of these feathers naturally somewhat reduced. +(27. Mr. Sproat has suggested ('Scenes and Studies of Savage Life,' 1868, +p. 25) this same view. Some distinguished ethnologists, amongst others M. +Gosse of Geneva, believe that artificial modifications of the skull tend to +be inherited.) Nevertheless, with mankind the habit of eradicating the +beard and the hairs on the body would probably not have arisen until these +had already become by some means reduced. + +It is difficult to form any judgment as to how the hair on the head became +developed to its present great length in many races. Eschricht (28. +'Ueber die Richtung,' ibid. s. 40.) states that in the human foetus the +hair on the face during the fifth month is longer than that on the head; +and this indicates that our semi-human progenitors were not furnished with +long tresses, which must therefore have been a late acquisition. This is +likewise indicated by the extraordinary difference in the length of the +hair in the different races; in the negro the hair forms a mere curly mat; +with us it is of great length, and with the American natives it not rarely +reaches to the ground. Some species of Semnopithecus have their heads +covered with moderately long hair, and this probably serves as an ornament +and was acquired through sexual selection. The same view may perhaps be +extended to mankind, for we know that long tresses are now and were +formerly much admired, as may be observed in the works of almost every +poet; St. Paul says, "if a woman have long hair, it is a glory to her;" and +we have seen that in North America a chief was elected solely from the +length of his hair. + +COLOUR OF THE SKIN. + +The best kind of evidence that in man the colour of the skin has been +modified through sexual selection is scanty; for in most races the sexes do +not differ in this respect, and only slightly, as we have seen, in others. +We know, however, from the many facts already given that the colour of the +skin is regarded by the men of all races as a highly important element in +their beauty; so that it is a character which would be likely to have been +modified through selection, as has occurred in innumerable instances with +the lower animals. It seems at first sight a monstrous supposition that +the jet-blackness of the negro should have been gained through sexual +selection; but this view is supported by various analogies, and we know +that negroes admire their own colour. With mammals, when the sexes differ +in colour, the male is often black or much darker than the female; and it +depends merely on the form of inheritance whether this or any other tint is +transmitted to both sexes or to one alone. The resemblance to a negro in +miniature of Pithecia satanas with his jet black skin, white rolling +eyeballs, and hair parted on the top of the head, is almost ludicrous. + +The colour of the face differs much more widely in the various kinds of +monkeys than it does in the races of man; and we have some reason to +believe that the red, blue, orange, almost white and black tints of their +skin, even when common to both sexes, as well as the bright colours of +their fur, and the ornamental tufts about the head, have all been acquired +through sexual selection. As the order of development during growth, +generally indicates the order in which the characters of a species have +been developed and modified during previous generations; and as the newly- +born infants of the various races of man do not differ nearly as much in +colour as do the adults, although their bodies are as completely destitute +of hair, we have some slight evidence that the tints of the different races +were acquired at a period subsequent to the removal of the hair, which must +have occurred at a very early period in the history of man. + +SUMMARY. + +We may conclude that the greater size, strength, courage, pugnacity, and +energy of man, in comparison with woman, were acquired during primeval +times, and have subsequently been augmented, chiefly through the contests +of rival males for the possession of the females. The greater intellectual +vigour and power of invention in man is probably due to natural selection, +combined with the inherited effects of habit, for the most able men will +have succeeded best in defending and providing for themselves and for their +wives and offspring. As far as the extreme intricacy of the subject +permits us to judge, it appears that our male ape-like progenitors acquired +their beards as an ornament to charm or excite the opposite sex, and +transmitted them only to their male offspring. The females apparently +first had their bodies denuded of hair, also as a sexual ornament; but they +transmitted this character almost equally to both sexes. It is not +improbable that the females were modified in other respects for the same +purpose and by the same means; so that women have acquired sweeter voices +and become more beautiful than men. + +It deserves attention that with mankind the conditions were in many +respects much more favourable for sexual selection, during a very early +period, when man had only just attained to the rank of manhood, than during +later times. For he would then, as we may safely conclude, have been +guided more by his instinctive passions, and less by foresight or reason. +He would have jealously guarded his wife or wives. He would not have +practised infanticide; nor valued his wives merely as useful slaves; nor +have been betrothed to them during infancy. Hence we may infer that the +races of men were differentiated, as far as sexual selection is concerned, +in chief part at a very remote epoch; and this conclusion throws light on +the remarkable fact that at the most ancient period, of which we have not +as yet any record, the races of man had already come to differ nearly or +quite as much as they do at the present day. + +The views here advanced, on the part which sexual selection has played in +the history of man, want scientific precision. He who does not admit this +agency in the case of the lower animals, will disregard all that I have +written in the later chapters on man. We cannot positively say that this +character, but not that, has been thus modified; it has, however, been +shewn that the races of man differ from each other and from their nearest +allies, in certain characters which are of no service to them in their +daily habits of life, and which it is extremely probable would have been +modified through sexual selection. We have seen that with the lowest +savages the people of each tribe admire their own characteristic +qualities,--the shape of the head and face, the squareness of the cheek- +bones, the prominence or depression of the nose, the colour of the skin, +the length of the hair on the head, the absence of hair on the face and +body, or the presence of a great beard, and so forth. Hence these and +other such points could hardly fail to be slowly and gradually exaggerated, +from the more powerful and able men in each tribe, who would succeed in +rearing the largest number of offspring, having selected during many +generations for their wives the most strongly characterised and therefore +most attractive women. For my own part I conclude that of all the causes +which have led to the differences in external appearance between the races +of man, and to a certain extent between man and the lower animals, sexual +selection has been the most efficient. + + +CHAPTER XXI. + +GENERAL SUMMARY AND CONCLUSION. + +Main conclusion that man is descended from some lower form--Manner of +development--Genealogy of man--Intellectual and moral faculties--Sexual +Selection--Concluding remarks. + +A brief summary will be sufficient to recall to the reader's mind the more +salient points in this work. Many of the views which have been advanced +are highly speculative, and some no doubt will prove erroneous; but I have +in every case given the reasons which have led me to one view rather than +to another. It seemed worth while to try how far the principle of +evolution would throw light on some of the more complex problems in the +natural history of man. False facts are highly injurious to the progress +of science, for they often endure long; but false views, if supported by +some evidence, do little harm, for every one takes a salutary pleasure in +proving their falseness: and when this is done, one path towards error is +closed and the road to truth is often at the same time opened. + +The main conclusion here arrived at, and now held by many naturalists who +are well competent to form a sound judgment, is that man is descended from +some less highly organised form. The grounds upon which this conclusion +rests will never be shaken, for the close similarity between man and the +lower animals in embryonic development, as well as in innumerable points of +structure and constitution, both of high and of the most trifling +importance,--the rudiments which he retains, and the abnormal reversions to +which he is occasionally liable,--are facts which cannot be disputed. They +have long been known, but until recently they told us nothing with respect +to the origin of man. Now when viewed by the light of our knowledge of the +whole organic world, their meaning is unmistakable. The great principle of +evolution stands up clear and firm, when these groups or facts are +considered in connection with others, such as the mutual affinities of the +members of the same group, their geographical distribution in past and +present times, and their geological succession. It is incredible that all +these facts should speak falsely. He who is not content to look, like a +savage, at the phenomena of nature as disconnected, cannot any longer +believe that man is the work of a separate act of creation. He will be +forced to admit that the close resemblance of the embryo of man to that, +for instance, of a dog--the construction of his skull, limbs and whole +frame on the same plan with that of other mammals, independently of the +uses to which the parts may be put--the occasional re-appearance of various +structures, for instance of several muscles, which man does not normally +possess, but which are common to the Quadrumana--and a crowd of analogous +facts--all point in the plainest manner to the conclusion that man is the +co-descendant with other mammals of a common progenitor. + +We have seen that man incessantly presents individual differences in all +parts of his body and in his mental faculties. These differences or +variations seem to be induced by the same general causes, and to obey the +same laws as with the lower animals. In both cases similar laws of +inheritance prevail. Man tends to increase at a greater rate than his +means of subsistence; consequently he is occasionally subjected to a severe +struggle for existence, and natural selection will have effected whatever +lies within its scope. A succession of strongly-marked variations of a +similar nature is by no means requisite; slight fluctuating differences in +the individual suffice for the work of natural selection; not that we have +any reason to suppose that in the same species, all parts of the +organisation tend to vary to the same degree. We may feel assured that the +inherited effects of the long-continued use or disuse of parts will have +done much in the same direction with natural selection. Modifications +formerly of importance, though no longer of any special use, are long- +inherited. When one part is modified, other parts change through the +principle of correlation, of which we have instances in many curious cases +of correlated monstrosities. Something may be attributed to the direct and +definite action of the surrounding conditions of life, such as abundant +food, heat or moisture; and lastly, many characters of slight physiological +importance, some indeed of considerable importance, have been gained +through sexual selection. + +No doubt man, as well as every other animal, presents structures, which +seem to our limited knowledge, not to be now of any service to him, nor to +have been so formerly, either for the general conditions of life, or in the +relations of one sex to the other. Such structures cannot be accounted for +by any form of selection, or by the inherited effects of the use and disuse +of parts. We know, however, that many strange and strongly-marked +peculiarities of structure occasionally appear in our domesticated +productions, and if their unknown causes were to act more uniformly, they +would probably become common to all the individuals of the species. We may +hope hereafter to understand something about the causes of such occasional +modifications, especially through the study of monstrosities: hence the +labours of experimentalists, such as those of M. Camille Dareste, are full +of promise for the future. In general we can only say that the cause of +each slight variation and of each monstrosity lies much more in the +constitution of the organism, than in the nature of the surrounding +conditions; though new and changed conditions certainly play an important +part in exciting organic changes of many kinds. + +Through the means just specified, aided perhaps by others as yet +undiscovered, man has been raised to his present state. But since he +attained to the rank of manhood, he has diverged into distinct races, or as +they may be more fitly called, sub-species. Some of these, such as the +Negro and European, are so distinct that, if specimens had been brought to +a naturalist without any further information, they would undoubtedly have +been considered by him as good and true species. Nevertheless all the +races agree in so many unimportant details of structure and in so many +mental peculiarities that these can be accounted for only by inheritance +from a common progenitor; and a progenitor thus characterised would +probably deserve to rank as man. + +It must not be supposed that the divergence of each race from the other +races, and of all from a common stock, can be traced back to any one pair +of progenitors. On the contrary, at every stage in the process of +modification, all the individuals which were in any way better fitted for +their conditions of life, though in different degrees, would have survived +in greater numbers than the less well-fitted. The process would have been +like that followed by man, when he does not intentionally select particular +individuals, but breeds from all the superior individuals, and neglects the +inferior. He thus slowly but surely modifies his stock, and unconsciously +forms a new strain. So with respect to modifications acquired +independently of selection, and due to variations arising from the nature +of the organism and the action of the surrounding conditions, or from +changed habits of life, no single pair will have been modified much more +than the other pairs inhabiting the same country, for all will have been +continually blended through free intercrossing. + +By considering the embryological structure of man,--the homologies which he +presents with the lower animals,--the rudiments which he retains,--and the +reversions to which he is liable, we can partly recall in imagination the +former condition of our early progenitors; and can approximately place them +in their proper place in the zoological series. We thus learn that man is +descended from a hairy, tailed quadruped, probably arboreal in its habits, +and an inhabitant of the Old World. This creature, if its whole structure +had been examined by a naturalist, would have been classed amongst the +Quadrumana, as surely as the still more ancient progenitor of the Old and +New World monkeys. The Quadrumana and all the higher mammals are probably +derived from an ancient marsupial animal, and this through a long line of +diversified forms, from some amphibian-like creature, and this again from +some fish-like animal. In the dim obscurity of the past we can see that +the early progenitor of all the Vertebrata must have been an aquatic +animal, provided with branchiae, with the two sexes united in the same +individual, and with the most important organs of the body (such as the +brain and heart) imperfectly or not at all developed. This animal seems to +have been more like the larvae of the existing marine Ascidians than any +other known form. + +The high standard of our intellectual powers and moral disposition is the +greatest difficulty which presents itself, after we have been driven to +this conclusion on the origin of man. But every one who admits the +principle of evolution, must see that the mental powers of the higher +animals, which are the same in kind with those of man, though so different +in degree, are capable of advancement. Thus the interval between the +mental powers of one of the higher apes and of a fish, or between those of +an ant and scale-insect, is immense; yet their development does not offer +any special difficulty; for with our domesticated animals, the mental +faculties are certainly variable, and the variations are inherited. No one +doubts that they are of the utmost importance to animals in a state of +nature. Therefore the conditions are favourable for their development +through natural selection. The same conclusion may be extended to man; the +intellect must have been all-important to him, even at a very remote +period, as enabling him to invent and use language, to make weapons, tools, +traps, etc., whereby with the aid of his social habits, he long ago became +the most dominant of all living creatures. + +A great stride in the development of the intellect will have followed, as +soon as the half-art and half-instinct of language came into use; for the +continued use of language will have reacted on the brain and produced an +inherited effect; and this again will have reacted on the improvement of +language. As Mr. Chauncey Wright (1. 'On the Limits of Natural +Selection,' in the 'North American Review,' Oct. 1870, p. 295.) has well +remarked, the largeness of the brain in man relatively to his body, +compared with the lower animals, may be attributed in chief part to the +early use of some simple form of language,--that wonderful engine which +affixes signs to all sorts of objects and qualities, and excites trains of +thought which would never arise from the mere impression of the senses, or +if they did arise could not be followed out. The higher intellectual +powers of man, such as those of ratiocination, abstraction, self- +consciousness, etc., probably follow from the continued improvement and +exercise of the other mental faculties. + +The development of the moral qualities is a more interesting problem. The +foundation lies in the social instincts, including under this term the +family ties. These instincts are highly complex, and in the case of the +lower animals give special tendencies towards certain definite actions; but +the more important elements are love, and the distinct emotion of sympathy. +Animals endowed with the social instincts take pleasure in one another's +company, warn one another of danger, defend and aid one another in many +ways. These instincts do not extend to all the individuals of the species, +but only to those of the same community. As they are highly beneficial to +the species, they have in all probability been acquired through natural +selection. + +A moral being is one who is capable of reflecting on his past actions and +their motives--of approving of some and disapproving of others; and the +fact that man is the one being who certainly deserves this designation, is +the greatest of all distinctions between him and the lower animals. But in +the fourth chapter I have endeavoured to shew that the moral sense follows, +firstly, from the enduring and ever-present nature of the social instincts; +secondly, from man's appreciation of the approbation and disapprobation of +his fellows; and thirdly, from the high activity of his mental faculties, +with past impressions extremely vivid; and in these latter respects he +differs from the lower animals. Owing to this condition of mind, man +cannot avoid looking both backwards and forwards, and comparing past +impressions. Hence after some temporary desire or passion has mastered his +social instincts, he reflects and compares the now weakened impression of +such past impulses with the ever-present social instincts; and he then +feels that sense of dissatisfaction which all unsatisfied instincts leave +behind them, he therefore resolves to act differently for the future,--and +this is conscience. Any instinct, permanently stronger or more enduring +than another, gives rise to a feeling which we express by saying that it +ought to be obeyed. A pointer dog, if able to reflect on his past conduct, +would say to himself, I ought (as indeed we say of him) to have pointed at +that hare and not have yielded to the passing temptation of hunting it. + +Social animals are impelled partly by a wish to aid the members of their +community in a general manner, but more commonly to perform certain +definite actions. Man is impelled by the same general wish to aid his +fellows; but has few or no special instincts. He differs also from the +lower animals in the power of expressing his desires by words, which thus +become a guide to the aid required and bestowed. The motive to give aid is +likewise much modified in man: it no longer consists solely of a blind +instinctive impulse, but is much influenced by the praise or blame of his +fellows. The appreciation and the bestowal of praise and blame both rest +on sympathy; and this emotion, as we have seen, is one of the most +important elements of the social instincts. Sympathy, though gained as an +instinct, is also much strengthened by exercise or habit. As all men +desire their own happiness, praise or blame is bestowed on actions and +motives, according as they lead to this end; and as happiness is an +essential part of the general good, the greatest-happinesss principle +indirectly serves as a nearly safe standard of right and wrong. As the +reasoning powers advance and experience is gained, the remoter effects of +certain lines of conduct on the character of the individual, and on the +general good, are perceived; and then the self-regarding virtues come +within the scope of public opinion, and receive praise, and their opposites +blame. But with the less civilised nations reason often errs, and many bad +customs and base superstitions come within the same scope, and are then +esteemed as high virtues, and their breach as heavy crimes. + +The moral faculties are generally and justly esteemed as of higher value +than the intellectual powers. But we should bear in mind that the activity +of the mind in vividly recalling past impressions is one of the fundamental +though secondary bases of conscience. This affords the strongest argument +for educating and stimulating in all possible ways the intellectual +faculties of every human being. No doubt a man with a torpid mind, if his +social affections and sympathies are well developed, will be led to good +actions, and may have a fairly sensitive conscience. But whatever renders +the imagination more vivid and strengthens the habit of recalling and +comparing past impressions, will make the conscience more sensitive, and +may even somewhat compensate for weak social affections and sympathies. + +The moral nature of man has reached its present standard, partly through +the advancement of his reasoning powers and consequently of a just public +opinion, but especially from his sympathies having been rendered more +tender and widely diffused through the effects of habit, example, +instruction, and reflection. It is not improbable that after long practice +virtuous tendencies may be inherited. With the more civilised races, the +conviction of the existence of an all-seeing Deity has had a potent +influence on the advance of morality. Ultimately man does not accept the +praise or blame of his fellows as his sole guide, though few escape this +influence, but his habitual convictions, controlled by reason, afford him +the safest rule. His conscience then becomes the supreme judge and +monitor. Nevertheless the first foundation or origin of the moral sense +lies in the social instincts, including sympathy; and these instincts no +doubt were primarily gained, as in the case of the lower animals, through +natural selection. + +The belief in God has often been advanced as not only the greatest, but the +most complete of all the distinctions between man and the lower animals. +It is however impossible, as we have seen, to maintain that this belief is +innate or instinctive in man. On the other hand a belief in all-pervading +spiritual agencies seems to be universal; and apparently follows from a +considerable advance in man's reason, and from a still greater advance in +his faculties of imagination, curiosity and wonder. I am aware that the +assumed instinctive belief in God has been used by many persons as an +argument for His existence. But this is a rash argument, as we should thus +be compelled to believe in the existence of many cruel and malignant +spirits, only a little more powerful than man; for the belief in them is +far more general than in a beneficent Deity. The idea of a universal and +beneficent Creator does not seem to arise in the mind of man, until he has +been elevated by long-continued culture. + +He who believes in the advancement of man from some low organised form, +will naturally ask how does this bear on the belief in the immortality of +the soul. The barbarous races of man, as Sir J. Lubbock has shewn, possess +no clear belief of this kind; but arguments derived from the primeval +beliefs of savages are, as we have just seen, of little or no avail. Few +persons feel any anxiety from the impossibility of determining at what +precise period in the development of the individual, from the first trace +of a minute germinal vesicle, man becomes an immortal being; and there is +no greater cause for anxiety because the period cannot possibly be +determined in the gradually ascending organic scale. (2. The Rev. J.A. +Picton gives a discussion to this effect in his 'New Theories and the Old +Faith,' 1870.) + +I am aware that the conclusions arrived at in this work will be denounced +by some as highly irreligious; but he who denounces them is bound to shew +why it is more irreligious to explain the origin of man as a distinct +species by descent from some lower form, through the laws of variation and +natural selection, than to explain the birth of the individual through the +laws of ordinary reproduction. The birth both of the species and of the +individual are equally parts of that grand sequence of events, which our +minds refuse to accept as the result of blind chance. The understanding +revolts at such a conclusion, whether or not we are able to believe that +every slight variation of structure,--the union of each pair in marriage, +the dissemination of each seed,--and other such events, have all been +ordained for some special purpose. + +Sexual selection has been treated at great length in this work; for, as I +have attempted to shew, it has played an important part in the history of +the organic world. I am aware that much remains doubtful, but I have +endeavoured to give a fair view of the whole case. In the lower divisions +of the animal kingdom, sexual selection seems to have done nothing: such +animals are often affixed for life to the same spot, or have the sexes +combined in the same individual, or what is still more important, their +perceptive and intellectual faculties are not sufficiently advanced to +allow of the feelings of love and jealousy, or of the exertion of choice. +When, however, we come to the Arthropoda and Vertebrata, even to the lowest +classes in these two great Sub-Kingdoms, sexual selection has effected +much. + +In the several great classes of the animal kingdom,--in mammals, birds, +reptiles, fishes, insects, and even crustaceans,--the differences between +the sexes follow nearly the same rules. The males are almost always the +wooers; and they alone are armed with special weapons for fighting with +their rivals. They are generally stronger and larger than the females, and +are endowed with the requisite qualities of courage and pugnacity. They +are provided, either exclusively or in a much higher degree than the +females, with organs for vocal or instrumental music, and with odoriferous +glands. They are ornamented with infinitely diversified appendages, and +with the most brilliant or conspicuous colours, often arranged in elegant +patterns, whilst the females are unadorned. When the sexes differ in more +important structures, it is the male which is provided with special sense- +organs for discovering the female, with locomotive organs for reaching her, +and often with prehensile organs for holding her. These various structures +for charming or securing the female are often developed in the male during +only part of the year, namely the breeding-season. They have in many cases +been more or less transferred to the females; and in the latter case they +often appear in her as mere rudiments. They are lost or never gained by +the males after emasculation. Generally they are not developed in the male +during early youth, but appear a short time before the age for +reproduction. Hence in most cases the young of both sexes resemble each +other; and the female somewhat resembles her young offspring throughout +life. In almost every great class a few anomalous cases occur, where there +has been an almost complete transposition of the characters proper to the +two sexes; the females assuming characters which properly belong to the +males. This surprising uniformity in the laws regulating the differences +between the sexes in so many and such widely separated classes, is +intelligible if we admit the action of one common cause, namely sexual +selection. + +Sexual selection depends on the success of certain individuals over others +of the same sex, in relation to the propagation of the species; whilst +natural selection depends on the success of both sexes, at all ages, in +relation to the general conditions of life. The sexual struggle is of two +kinds; in the one it is between individuals of the same sex, generally the +males, in order to drive away or kill their rivals, the females remaining +passive; whilst in the other, the struggle is likewise between the +individuals of the same sex, in order to excite or charm those of the +opposite sex, generally the females, which no longer remain passive, but +select the more agreeable partners. This latter kind of selection is +closely analogous to that which man unintentionally, yet effectually, +brings to bear on his domesticated productions, when he preserves during a +long period the most pleasing or useful individuals, without any wish to +modify the breed. + +The laws of inheritance determine whether characters gained through sexual +selection by either sex shall be transmitted to the same sex, or to both; +as well as the age at which they shall be developed. It appears that +variations arising late in life are commonly transmitted to one and the +same sex. Variability is the necessary basis for the action of selection, +and is wholly independent of it. It follows from this, that variations of +the same general nature have often been taken advantage of and accumulated +through sexual selection in relation to the propagation of the species, as +well as through natural selection in relation to the general purposes of +life. Hence secondary sexual characters, when equally transmitted to both +sexes can be distinguished from ordinary specific characters only by the +light of analogy. The modifications acquired through sexual selection are +often so strongly pronounced that the two sexes have frequently been ranked +as distinct species, or even as distinct genera. Such strongly-marked +differences must be in some manner highly important; and we know that they +have been acquired in some instances at the cost not only of inconvenience, +but of exposure to actual danger. + +The belief in the power of sexual selection rests chiefly on the following +considerations. Certain characters are confined to one sex; and this alone +renders it probable that in most cases they are connected with the act of +reproduction. In innumerable instances these characters are fully +developed only at maturity, and often during only a part of the year, which +is always the breeding-season. The males (passing over a few exceptional +cases) are the more active in courtship; they are the better armed, and are +rendered the more attractive in various ways. It is to be especially +observed that the males display their attractions with elaborate care in +the presence of the females; and that they rarely or never display them +excepting during the season of love. It is incredible that all this should +be purposeless. Lastly we have distinct evidence with some quadrupeds and +birds, that the individuals of one sex are capable of feeling a strong +antipathy or preference for certain individuals of the other sex. + +Bearing in mind these facts, and the marked results of man's unconscious +selection, when applied to domesticated animals and cultivated plants, it +seems to me almost certain that if the individuals of one sex were during a +long series of generations to prefer pairing with certain individuals of +the other sex, characterised in some peculiar manner, the offspring would +slowly but surely become modified in this same manner. I have not +attempted to conceal that, excepting when the males are more numerous than +the females, or when polygamy prevails, it is doubtful how the more +attractive males succeed in leaving a large number of offspring to inherit +their superiority in ornaments or other charms than the less attractive +males; but I have shewn that this would probably follow from the females,-- +especially the more vigorous ones, which would be the first to breed,-- +preferring not only the more attractive but at the same time the more +vigorous and victorious males. + +Although we have some positive evidence that birds appreciate bright and +beautiful objects, as with the bower-birds of Australia, and although they +certainly appreciate the power of song, yet I fully admit that it is +astonishing that the females of many birds and some mammals should be +endowed with sufficient taste to appreciate ornaments, which we have reason +to attribute to sexual selection; and this is even more astonishing in the +case of reptiles, fish, and insects. But we really know little about the +minds of the lower animals. It cannot be supposed, for instance, that male +birds of paradise or peacocks should take such pains in erecting, +spreading, and vibrating their beautiful plumes before the females for no +purpose. We should remember the fact given on excellent authority in a +former chapter, that several peahens, when debarred from an admired male, +remained widows during a whole season rather than pair with another bird. + +Nevertheless I know of no fact in natural history more wonderful than that +the female Argus pheasant should appreciate the exquisite shading of the +ball-and-socket ornaments and the elegant patterns on the wing-feather of +the male. He who thinks that the male was created as he now exists must +admit that the great plumes, which prevent the wings from being used for +flight, and which are displayed during courtship and at no other time in a +manner quite peculiar to this one species, were given to him as an +ornament. If so, he must likewise admit that the female was created and +endowed with the capacity of appreciating such ornaments. I differ only in +the conviction that the male Argus pheasant acquired his beauty gradually, +through the preference of the females during many generations for the more +highly ornamented males; the aesthetic capacity of the females having been +advanced through exercise or habit, just as our own taste is gradually +improved. In the male through the fortunate chance of a few feathers being +left unchanged, we can distinctly trace how simple spots with a little +fulvous shading on one side may have been developed by small steps into the +wonderful ball-and-socket ornaments; and it is probable that they were +actually thus developed. + +Everyone who admits the principle of evolution, and yet feels great +difficulty in admitting that female mammals, birds, reptiles, and fish, +could have acquired the high taste implied by the beauty of the males, and +which generally coincides with our own standard, should reflect that the +nerve-cells of the brain in the highest as well as in the lowest members of +the Vertebrate series, are derived from those of the common progenitor of +this great Kingdom. For we can thus see how it has come to pass that +certain mental faculties, in various and widely distinct groups of animals, +have been developed in nearly the same manner and to nearly the same +degree. + +The reader who has taken the trouble to go through the several chapters +devoted to sexual selection, will be able to judge how far the conclusions +at which I have arrived are supported by sufficient evidence. If he +accepts these conclusions he may, I think, safely extend them to mankind; +but it would be superfluous here to repeat what I have so lately said on +the manner in which sexual selection apparently has acted on man, both on +the male and female side, causing the two sexes to differ in body and mind, +and the several races to differ from each other in various characters, as +well as from their ancient and lowly-organised progenitors. + +He who admits the principle of sexual selection will be led to the +remarkable conclusion that the nervous system not only regulates most of +the existing functions of the body, but has indirectly influenced the +progressive development of various bodily structures and of certain mental +qualities. Courage, pugnacity, perseverance, strength and size of body, +weapons of all kinds, musical organs, both vocal and instrumental, bright +colours and ornamental appendages, have all been indirectly gained by the +one sex or the other, through the exertion of choice, the influence of love +and jealousy, and the appreciation of the beautiful in sound, colour or +form; and these powers of the mind manifestly depend on the development of +the brain. + +Man scans with scrupulous care the character and pedigree of his horses, +cattle, and dogs before he matches them; but when he comes to his own +marriage he rarely, or never, takes any such care. He is impelled by +nearly the same motives as the lower animals, when they are left to their +own free choice, though he is in so far superior to them that he highly +values mental charms and virtues. On the other hand he is strongly +attracted by mere wealth or rank. Yet he might by selection do something +not only for the bodily constitution and frame of his offspring, but for +their intellectual and moral qualities. Both sexes ought to refrain from +marriage if they are in any marked degree inferior in body or mind; but +such hopes are Utopian and will never be even partially realised until the +laws of inheritance are thoroughly known. Everyone does good service, who +aids towards this end. When the principles of breeding and inheritance are +better understood, we shall not hear ignorant members of our legislature +rejecting with scorn a plan for ascertaining whether or not consanguineous +marriages are injurious to man. + +The advancement of the welfare of mankind is a most intricate problem: all +ought to refrain from marriage who cannot avoid abject poverty for their +children; for poverty is not only a great evil, but tends to its own +increase by leading to recklessness in marriage. On the other hand, as Mr. +Galton has remarked, if the prudent avoid marriage, whilst the reckless +marry, the inferior members tend to supplant the better members of society. +Man, like every other animal, has no doubt advanced to his present high +condition through a struggle for existence consequent on his rapid +multiplication; and if he is to advance still higher, it is to be feared +that he must remain subject to a severe struggle. Otherwise he would sink +into indolence, and the more gifted men would not be more successful in the +battle of life than the less gifted. Hence our natural rate of increase, +though leading to many and obvious evils, must not be greatly diminished by +any means. There should be open competition for all men; and the most able +should not be prevented by laws or customs from succeeding best and rearing +the largest number of offspring. Important as the struggle for existence +has been and even still is, yet as far as the highest part of man's nature +is concerned there are other agencies more important. For the moral +qualities are advanced, either directly or indirectly, much more through +the effects of habit, the reasoning powers, instruction, religion, etc., +than through natural selection; though to this latter agency may be safely +attributed the social instincts, which afforded the basis for the +development of the moral sense. + +The main conclusion arrived at in this work, namely, that man is descended +from some lowly organised form, will, I regret to think, be highly +distasteful to many. But there can hardly be a doubt that we are descended +from barbarians. The astonishment which I felt on first seeing a party of +Fuegians on a wild and broken shore will never be forgotten by me, for the +reflection at once rushed into my mind--such were our ancestors. These men +were absolutely naked and bedaubed with paint, their long hair was tangled, +their mouths frothed with excitement, and their expression was wild, +startled, and distrustful. They possessed hardly any arts, and like wild +animals lived on what they could catch; they had no government, and were +merciless to every one not of their own small tribe. He who has seen a +savage in his native land will not feel much shame, if forced to +acknowledge that the blood of some more humble creature flows in his veins. +For my own part I would as soon be descended from that heroic little +monkey, who braved his dreaded enemy in order to save the life of his +keeper, or from that old baboon, who descending from the mountains, carried +away in triumph his young comrade from a crowd of astonished dogs--as from +a savage who delights to torture his enemies, offers up bloody sacrifices, +practices infanticide without remorse, treats his wives like slaves, knows +no decency, and is haunted by the grossest superstitions. + +Man may be excused for feeling some pride at having risen, though not +through his own exertions, to the very summit of the organic scale; and the +fact of his having thus risen, instead of having been aboriginally placed +there, may give him hope for a still higher destiny in the distant future. +But we are not here concerned with hopes or fears, only with the truth as +far as our reason permits us to discover it; and I have given the evidence +to the best of my ability. We must, however, acknowledge, as it seems to +me, that man with all his noble qualities, with sympathy which feels for +the most debased, with benevolence which extends not only to other men but +to the humblest living creature, with his god-like intellect which has +penetrated into the movements and constitution of the solar system--with +all these exalted powers--Man still bears in his bodily frame the indelible +stamp of his lowly origin. + + +SUPPLEMENTAL NOTE. + +ON SEXUAL SELECTION IN RELATION TO MONKEYS. + +Reprinted from NATURE, November 2, 1876, p. 18. + +In the discussion on Sexual Selection in my 'Descent of Man,' no case +interested and perplexed me so much as the brightly-coloured hinder ends +and adjoining parts of certain monkeys. As these parts are more brightly +coloured in one sex than the other, and as they become more brilliant +during the season of love, I concluded that the colours had been gained as +a sexual attraction. I was well aware that I thus laid myself open to +ridicule; though in fact it is not more surprising that a monkey should +display his bright-red hinder end than that a peacock should display his +magnificent tail. I had, however, at that time no evidence of monkeys +exhibiting this part of their bodies during their courtship; and such +display in the case of birds affords the best evidence that the ornaments +of the males are of service to them by attracting or exciting the females. +I have lately read an article by Joh. von Fischer, of Gotha, published in +'Der Zoologische Garten,' April 1876, on the expression of monkeys under +various emotions, which is well worthy of study by any one interested in +the subject, and which shews that the author is a careful and acute +observer. In this article there is an account of the behaviour of a young +male mandrill when he first beheld himself in a looking-glass, and it is +added, that after a time he turned round and presented his red hinder end +to the glass. Accordingly I wrote to Herr J. von Fischer to ask what he +supposed was the meaning of this strange action, and he has sent me two +long letters full of new and curious details, which will, I hope, be +hereafter published. He says that he was himself at first perplexed by the +above action, and was thus led carefully to observe several individuals of +various other species of monkeys, which he has long kept in his house. He +finds that not only the mandrill (Cynocephalus mormon) but the drill (C. +leucophaeus) and three other kinds of baboons (C. hamadryas, sphinx, and +babouin), also Cynopithecus niger, and Macacus rhesus and nemestrinus, turn +this part of their bodies, which in all these species is more or less +brightly coloured, to him when they are pleased, and to other persons as a +sort of greeting. He took pains to cure a Macacus rhesus, which he had +kept for five years, of this indecorous habit, and at last succeeded. +These monkeys are particularly apt to act in this manner, grinning at the +same time, when first introduced to a new monkey, but often also to their +old monkey friends; and after this mutual display they begin to play +together. The young mandrill ceased spontaneously after a time to act in +this manner towards his master, von Fischer, but continued to do so towards +persons who were strangers and to new monkeys. A young Cynopithecus niger +never acted, excepting on one occasion, in this way towards his master, but +frequently towards strangers, and continues to do so up to the present +time. From these facts Von Fischer concludes that the monkeys which +behaved in this manner before a looking-glass (viz., the mandrill, drill, +Cynopithecus niger, Macacus rhesus and nemestrinus) acted as if their +reflection were a new acquaintance. The mandrill and drill, which have +their hinder ends especially ornamented, display it even whilst quite +young, more frequently and more ostentatiously than do the other kinds. +Next in order comes Cynocephalus hamadryas, whilst the other species act in +this manner seldomer. The individuals, however, of the same species vary +in this respect, and some which were very shy never displayed their hinder +ends. It deserves especial attention that Von Fischer has never seen any +species purposely exhibit the hinder part of its body, if not at all +coloured. This remark applies to many individuals of Macacus cynomolgus +and Cercocebus radiatus (which is closely allied to M. rhesus), to three +species of Cercopithecus and several American monkeys. The habit of +turning the hinder ends as a greeting to an old friend or new acquaintance, +which seems to us so odd, is not really more so than the habits of many +savages, for instance that of rubbing their bellies with their hands, or +rubbing noses together. The habit with the mandrill and drill seems to be +instinctive or inherited, as it was followed by very young animals; but it +is modified or guided, like so many other instincts, by observation, for +Von Fischer says that they take pains to make their display fully; and if +made before two observers, they turn to him who seems to pay the most +attention. + +With respect to the origin of the habit, Von Fischer remarks that his +monkeys like to have their naked hinder ends patted or stroked, and that +they then grunt with pleasure. They often also turn this part of their +bodies to other monkeys to have bits of dirt picked off, and so no doubt it +would be with respect to thorns. But the habit with adult animals is +connected to a certain extent with sexual feelings, for Von Fischer watched +through a glass door a female Cynopithecus niger, and she during several +days, "umdrehte und dem Männchen mit gurgelnden Tönen die stark geröthete +Sitzflache zeigte, was ich früher nie an diesem Thier bemerkt hatte. Beim +Anblick dieses Gegenstandes erregte sich das Männchen sichtlich, denn es +polterte heftig an den Stäben, ebenfalls gurgelnde Laute ausstossend." As +all the monkeys which have the hinder parts of their bodies more or less +brightly coloured live, according to Von Fischer, in open rocky places, he +thinks that these colours serve to render one sex conspicuous at a distance +to the other; but, as monkeys are such gregarious animals, I should have +thought that there was no need for the sexes to recognise each other at a +distance. It seems to me more probable that the bright colours, whether on +the face or hinder end, or, as in the mandrill, on both, serve as a sexual +ornament and attraction. Anyhow, as we now know that monkeys have the +habit of turning their hinder ends towards other monkeys, it ceases to be +at all surprising that it should have been this part of their bodies which +has been more or less decorated. The fact that it is only the monkeys thus +characterised which, as far as at present known, act in this manner as a +greeting towards other monkeys renders it doubtful whether the habit was +first acquired from some independent cause, and that afterwards the parts +in question were coloured as a sexual ornament; or whether the colouring +and the habit of turning round were first acquired through variation and +sexual selection, and that afterwards the habit was retained as a sign of +pleasure or as a greeting, through the principle of inherited association. +This principle apparently comes into play on many occasions: thus it is +generally admitted that the songs of birds serve mainly as an attraction +during the season of love, and that the leks, or great congregations of the +black-grouse, are connected with their courtship; but the habit of singing +has been retained by some birds when they feel happy, for instance by the +common robin, and the habit of congregating has been retained by the black- +grouse during other seasons of the year. + +I beg leave to refer to one other point in relation to sexual selection. +It has been objected that this form of selection, as far as the ornaments +of the males are concerned, implies that all females within the same +district must possess and exercise exactly the same taste. It should, +however, be observed, in the first place, that although the range of +variation of a species may be very large, it is by no means indefinite. I +have elsewhere given a good instance of this fact in the pigeon, of which +there are at least a hundred varieties differing widely in their colours, +and at least a score of varieties of the fowl differing in the same kind of +way; but the range of colour in these two species is extremely distinct. +Therefore the females of natural species cannot have an unlimited scope for +their taste. In the second place, I presume that no supporter of the +principle of sexual selection believes that the females select particular +points of beauty in the males; they are merely excited or attracted in a +greater degree by one male than by another, and this seems often to depend, +especially with birds, on brilliant colouring. Even man, excepting perhaps +an artist, does not analyse the slight differences in the features of the +woman whom he may admire, on which her beauty depends. The male mandrill +has not only the hinder end of his body, but his face gorgeously coloured +and marked with oblique ridges, a yellow beard, and other ornaments. We +may infer from what we see of the variation of animals under domestication, +that the above several ornaments of the mandrill were gradually acquired by +one individual varying a little in one way, and another individual in +another way. The males which were the handsomest or the most attractive in +any manner to the females would pair oftenest, and would leave rather more +offspring than other males. The offspring of the former, although +variously intercrossed, would either inherit the peculiarities of their +fathers or transmit an increased tendency to vary in the same manner. +Consequently the whole body of males inhabiting the same country would tend +from the effects of constant intercrossing to become modified almost +uniformly, but sometimes a little more in one character and sometimes in +another, though at an extremely slow rate; all ultimately being thus +rendered more attractive to the females. The process is like that which I +have called unconscious selection by man, and of which I have given several +instances. In one country the inhabitants value a fleet or light dog or +horse, and in another country a heavier and more powerful one; in neither +country is there any selection of individual animals with lighter or +stronger bodies and limbs; nevertheless after a considerable lapse of time +the individuals are found to have been modified in the desired manner +almost uniformly, though differently in each country. In two absolutely +distinct countries inhabited by the same species, the individuals of which +can never during long ages have intermigrated and intercrossed, and where, +moreover, the variations will probably not have been identically the same, +sexual selection might cause the males to differ. Nor does the belief +appear to me altogether fanciful that two sets of females, surrounded by a +very different environment, would be apt to acquire somewhat different +tastes with respect to form, sound, or colour. However this may be, I have +given in my 'Descent of Man' instances of closely-allied birds inhabiting +distinct countries, of which the young and the females cannot be +distinguished, whilst the adult males differ considerably, and this may be +attributed with much probability to the action of sexual selection. + + + +INDEX. + +Abbot, C., on the battles of seals. + +Abductor of the fifth metatarsal, presence of, in man. + +Abercrombie, Dr., on disease of the brain affecting speech. + +Abipones, marriage customs of the. + +Abortion, prevalence of the practice of. + +Abou-Simbel, caves of. + +Abramis brama. + +Abstraction, power of, in animals. + +Acalles, stridulation of. + +Acanthodactylus capensis, sexual differences of colour in. + +Accentor Modularis. + +Acclimatisation, difference of, in different races of men. + +Achetidae, stridulation of the; +rudimentary stridulating organs in female. + +Acilius sulcatus, elytra of the female. + +Acomus, development of spurs in the female of. + +Acridiidae, stridulation of the; +rudimentary stridulating organs in female. + +Acromio-basilar muscle, and quadrupedal gait. + +Acting. + +Actiniae, bright colours of. + +Adams, Mr., migration of birds; +intelligence of nut-hatch; +on the Bombycilla carolinensis. + +Admiral butterfly. + +Adoption of the young of other animals by female monkeys. + +Advancement in the organic scale, Von Baer's definition of. + +Aeby, on the difference between the skulls of man and the quadrumana. + +Aesthetic faculty, not highly developed in savages. + +Affection, maternal; +manifestation of, by animals; +parental and filial, partly the result of natural selection; +mutual, of birds; +shewn by birds in confinement, for certain persons. + +Africa, probably the birthplace of man; +South, crossed population of; +South, retention of colour by the Dutch in; +South, proportion of the sexes in the butterflies of; +tattooing practised in; +Northern, coiffure of natives of. + +Agassiz, L., on conscience in dogs; +on the coincidence of the races of man with zoological provinces; +on the number of species of man; +on the courtship of the land-snails; +on the brightness of the colours of male fishes during the breeding season; +on the frontal protuberance of the males of Geophagus and Cichla; +male fishes hatching ova in their mouths; +sexual differences in colour of chromids; +on the slight sexual differences of the South Americans; +on the tattooing of the Amazonian Indians. + +Age, in relation to the transmission of characters in birds; +variation in accordance with, in birds. + +Agelaeus phoeniceus. + +Ageronia feronia, noise produced by. + +Agrion, dimorphism in. + +Agrion Ramburii, sexes of. + +Agrionidae, difference in the sexes of. + +Agrotis exclamationis. + +Ague, tertian, dog suffering from. + +Ainos, hairiness of the. + +Aitchison, Mr., on sheep. + +Aithurus polytmus, young of. + +Albino birds. + +Alca torda, young of. + +Alces palmata. + +Alder and Hancock, MM., on the nudi-branch mollusca. + +Allen, J.A., vigour of birds earliest hatched; +effect of difference of temperature, light, etc., on birds; +colours of birds; +on the relative size of the sexes of Callorhinus ursinus; +on the name of Otaria jubata; +on the pairing of seals; +on sexual differences in the colour of bats. + +Allen, S., on the habits of Hoplopterus; +on the plumes of herons; +on the vernal moult of Herodius bubulcus. + +Alligator, courtship of the male; +roaring of the male. + +Amadavat, pugnacity of male. + +Amadina Lathami, display of plumage by the male. + +Amadina castanotis, display of plumage by the male. + +Amazons, butterflies of the; +fishes of the. + +America, variation in the skulls of aborigines of; +wide range of aborigines of; +lice of the natives of; +general beardlessness of the natives of. + +America, North, butterflies of; +Indians of, women a cause of strife among the; +Indians of, their notions of female beauty. + +America, South, character of the natives of; +population of parts of; +piles of stones in; +extinction of the fossil horse of; +desert-birds of; +slight sexual difference of the aborigines of; +prevalence of infanticide in. + +American languages, often highly artificial. + +Americans, wide geographical range of; +native, variability of; +and negroes, difference of; +aversion of, to hair on the face. + +Ammophila, on the jaws of. + +Ammotragus tragelaphus, hairy forelegs of. + +Amphibia, affinity of, to the ganoid fishes; +vocal organs of the. + +Amphibians, breeding whilst immature. + +Amphioxus. + +Amphipoda, males sexually mature while young. + +Amunoph III., negro character of, features of. + +Anal appendages of insects. + +Analogous variation in the plumage of birds. + +Anas. + +Anas acuta, male plumage of. + +Anas boschas, male plumage of. + +Anas histrionica. + +Anas punctata. + +Anastomus oscitans, sexes and young of; +white nuptial plumage of. + +Anatidae, voices of. + +Anax junius, differences in the sexes of. + +Andaman islanders, susceptible to change of climate. + +Anderson, Dr., on the tail of Macacus brunneus; +the Bufo sikimmensis; +sounds of Echis carinata. + +Andreana fulva. + +Anglo-Saxons, estimation of the beard among the. + +Animals, domesticated, more fertile than wild; +cruelty of savages to; +characters common to man and; +domestic, change of breeds of. + +Annelida, colours of. + +Anobium tessellatum, sounds produced by. + +Anolis cristatellus, male, crest of; +pugnacity of the male; +throat-pouch of. + +Anser canadensis. + +Anset cygnoides; knob at the base of the beak of. + +Anser hyperboreus, whiteness of. + +Antelope, prong-horned, horns of. + +Antelopes, generally polygamous; +horns of; +canine teeth of some male; +use of horns of; +dorsal crests in; +dewlaps of; +winter change of two species of; +peculiar markings of. + +Antennae, furnished with cushions in the male of Penthe. + +Anthidium manicatum, large male of. + +Anthocharis cardamines; +sexual difference of colour in. + +Anthocharis genutia. + +Anthocharis sara. + +Anthophora acervorum, large male of. + +Anthophora retusa, difference of the sexes in. + +Anthropidae. + +Anthus, moulting of. + +Antics of birds. + +Antigua, Dr. Nicholson's observations on yellow fever in. + +Antilocapra americana, horns of. + +Antilope bezoartica, horned females of; +sexual difference in the colour of. + +Antilope Dorcas and euchore. + +Antilope euchore, horns of. + +Antilope montana, rudimentary canines in the young male of. + +Antilope niger, sing-sing, caama, and gorgon, sexual differences in the +colours of. + +Antilope oreas, horns of. + +Antilope saiga, polygamous habits of. + +Antilope strepsiceros, horns of. + +Antilope subgutturosa, absence of suborbital pits in. + +Antipathy, shewn by birds in confinement, to certain persons. + +Ants, large size of the cerebral ganglia in; +soldier, large jaws of; +playing together; +memory in; +intercommunication of, by means of the antennae; +habits of; +difference of the sexes in; +recognition of each other by, after separation. + +Ants White, habits of. + +Anura. + +Apatania muliebris, male unknown. + +Apathus, difference of the sexes in. + +Apatura Iris. + +Apes, difference of the young, from the adult; +semi-erect attitude of some; +mastoid processes of; +influences of the jaw-muscles on the physiognomy of; +female, destitute of large canines; +building platforms; +imitative faculties of; +anthropomorphous; +probable speedy extermination of the; +Gratiolet on the evolution of; +canine teeth of male; +females of some, less hairy beneath than the males. + +Apes, long-armed, their mode of progression. + +Aphasia, Dr. Bateman on. + +Apis mellifica, large male of. + +Apollo, Greek statues of. + +Apoplexy in Cebus Azarae. + +Appendages, anal, of insects. + +Approbation, influence of the love of. + +Aprosmictus scapulatus. + +Apus, proportion of sexes. + +Aquatic birds, frequency of white plumage in. + +Aquila chrysaetos. + +Arab women, elaborate and peculiar coiffure of. + +Arabs, fertility of crosses with other races; +gashing of cheeks and temples among the. + +Arachnida. + +Arakhan, artificial widening of the forehead by the natives of. + +Arboricola, young of. + +Archeopteryx. + +Arctiidae, coloration of the. + +Ardea asha, rufescens, and coerulea, change of colour in. + +Ardea coerulea, breeding in immature plumage. + +Ardea gularis, change of plumage in. + +Ardea herodias, love-gestures of the male. + +Ardea ludoviciana, age of mature plumage in; +continued growth of crest and plumes in the male of. + +Ardea nycticorax, cries of. + +Ardeola, young of. + +Ardetta, changes of plumage in. + +Argenteuil. + +Argus pheasant, display of plumage by the male; +ocellated spots of the; +gradation of characters in the. + +Argyll, Duke of, on the physical weakness of man; +the fashioning of implements peculiar to man; +on the contest in man between right and wrong; +on the primitive civilisation of man; +on the plumage of the male Argus pheasant; +on Urosticte Benjamini; +on the nests of birds. + +Argynnis, colouring of the lower surface of. + +Aricoris epitus, sexual differences in the wings of. + +Aristocracy, increased beauty of the. + +Arms, proportions of, in soldiers and sailors; +direction of the hair on the. + +Arms and hands, free use of, indirectly correlated with diminution of +canines. + +Arrest of development. + +Arrow-heads, stone, general resemblance of. + +Arrows, use of. + +Arteries, variations in the course of the. + +Artery, effect of tying, upon the lateral channels. + +Arthropoda. + +Arts practised by savages. + +Ascension, coloured incrustation on the rocks of. + +Ascidia, affinity of the lancelet to; +tad-pole like larvae of. + +Ascidians, bright colours of some. + +Asinus, Asiatic and African species of. + +Asinus taeniopus. + +Ass, colour-variations of the. + +Ateles, effects of brandy on an; +absence of the thumb in. + +Ateles beelzebuth, ears of. + +Ateles marginatus, colour of the ruff of; +hair on the head of. + +Ateuchus cicatricosus, habits of. + +Ateuchus stridulation of. + +Athalia, proportions of the sexes in. + +Atropus pulsatorius. + +Attention, manifestations of, in animals. + +Audouin, V., on a hymenopterous parasite with a sedentary male. + +Audubon, J.J., on the pinioned goose; +on the speculum of Mergus cucullatus; +on the pugnacity of male birds; +on courtship of Caprimulgus; +on Tetrao cupido; +on Ardea nycticorax; +on Sturnella ludoviciana; +on the vocal organs of Tetra cupido; +on the drumming of the male Tetrao umbellus; +on sounds produced by the nightjar; +on Ardea herodias and Cathartes jota; +on Mimus polyglottus; +on display in male birds; +on the spring change of colour in some finches; +on migration of mocking thrushes; +recognition of a dog by a turkey; +selection of mate by female birds; +on the turkey; +on variation in the male scarlet tanager; +on the musk-rat; +on the habits of Pyranga aestiva; +on local differences in the nests of the same species of birds; +on the habits of woodpeckers; +on Bombycilla carolinensis; +on young females of Pyranga aestiva acquiring male characters; +on the immature plumage of thrushes; +on the immature plumage of birds; +on birds breeding in immature plumage; +on the growth of the crest and plume in the male Ardea ludoviciana; +on the change of colour in some species of Ardea. + +Audobon and Bachman, MM., on squirrels fighting; +on the Canadian lynx. + +Aughey, Prof., on rattlesnakes. + +Austen, N.L., on Anolis cristatellus. + +Australia, not the birthplace of man; +half-castes killed by the natives of; +lice of the natives of. + +Australia, South, variation in the skulls of aborigines of. + +Australians, colour of new-born children of; +relative height of the sexes of; +women a cause of war among the. + +Axis deer, sexual difference in the colour of the. + +Aymaras, measurements of the; +no grey hair among the; +hairlessness of the face in the; +long hair of the. + +Azara, on the proportion of men and women among the Guaranys; +on Palamedea cornuta; +on the beards of the Guaranys; +on strife for women among the Guanas; +on infanticide; +on the eradication of the eyebrows and eyelashes by the Indians of +Paraguay; +on polyandry among the Guanas; +celibacy unknown among the savages of South America; +on the freedom of divorce among the Charruas. + +Babbage C., on the greater proportion of illegitimate female births. + +Babirusa, tusks of the. + +Baboon, revenge in a; +rage excited in, by reading; +manifestation of memory by a; +employing a mat for shelter against the sun; +protected from punishment by its companions. + +Baboon, Cape, mane of the male; +Hamadryas, mane of the male. + +Baboon, effects of intoxicating liquors on; +ears of; +diversity of the mental faculties in; +hands of; +habits of; +variability of the tail in; +manifestation of maternal affection by; +using stones and sticks as weapons; +co-operation of; +silence of, on plundering expeditions; +apparent polygamy of; +polygamous and social habits of. + +Baboons, courtship of. + +Bachman, Dr., on the fertility of mulattoes. + +Baer, K.E. von, on embryonic development; +definition of advancement in the organic scale. + +Bagehot, W., on the social virtues among primitive men; +slavery formerly beneficial; +on the value of obedience; +on human progress; +on the persistence of savage tribes in classical times. + +Bailly, E.M., on the mode of fighting of the Italian buffalo; +on the fighting of stags. + +Bain, A., on the sense of duty; +aid springing from sympathy; +on the basis of sympathy; +on the love of approbation etc.; +on the idea of beauty. + +Baird, W., on a difference in colour between the males and females of some +Entozoa. + +Baker, Mr., observation on the proportion of the sexes in pheasant-chicks. + +Baker, Sir S., on the fondness of the Arabs for discordant music; +on sexual difference in the colours of an antelope; +on the elephant and rhinoceros attacking white or grey horses; +on the disfigurements practised by the negroes; +on the gashing of the cheeks and temples practised in Arab countries; +on the coiffure of the North Africans; +on the perforation of the lower lip by the women of Latooka; +on the distinctive characters of the coiffure of central African tribes; +on the coiffure of Arab women. + +"Balz" of the Black-cock. + +Bantam, Sebright. + +Banteng, horns of; +sexual differences in the colours of the. + +Banyai, colour of the. + +Barbarism, primitive, of civilised nations. + +Barbs, filamentous, of the feathers, in certain birds. + +Barr, Mr., on sexual preference in dogs. + +Barrago, F., on the Simian resemblances of man. + +Barrington, Daines, on the language of birds; +on the clucking of the hen; +on the object of the song of birds; +on the singing of female birds; +on birds acquiring the songs of other birds; +on the muscles of the larynx in song-birds; +on the want of the power of song by female birds. + +Barrow, on the widow-bird. + +Bartels, Dr., supernumerary mammae in men. + +Bartlett, A.D., period of hatching of bird's eggs; +on the tragopan; +on the development of the spurs in Crossoptilon auritum; +on the fighting of the males of Plectopterus gambensis; +on the Knot; +on display in male birds; +on the display of plumage by the male Polyplectron; +on Crossoptilon auritum and Phasianus Wallichii; +on the habits of Lophophorus; +on the colour of the mouth in Buceros bicornis; +on the incubation of the cassowary; +on the Cape Buffalo; +on the use of the horns of antelopes; +on the fighting of male wart-hogs; +on Ammotragus tragelaphus; +on the colours of Cercopithecus cephus; +on the colours of the faces of monkeys; +on the naked surfaces of monkeys. + +Bartlett, on courting of Argus pheasant. + +Bartram, on the courtship of the male alligator. + +Basque language, highly artificial. + +Bate, C.S., on the superior activity of male crustacea; +on the proportions of the sexes in crabs; +on the chelae of crustacea; +on the relative size of the sexes in crustacea; +on the colours of crustacea. + +Bateman, Dr., tendency to imitation in certain diseased states; +on Aphasia. + +Bates, H.W., on variation in the form of the head of Amazonian Indians; +on the proportion of the sexes among Amazonian butterflies; +on sexual differences in the wings of butterflies; +on the field-cricket; +on Pyrodes pulcherrimus; +on the horns of Lamellicorn beetles; +on the colours of Epicaliae, etc.; +on the coloration of tropical butterflies; +on the variability of Papilio Sesostris and Childrenae; +on male and female butterflies inhabiting different stations; +on mimicry; +on the caterpillar of a Sphinx; +on the vocal organs of the umbrella-bird; +on the toucans; +on Brackyurus calvus. + +Batokas, knocking out two upper incisors. + +Batrachia, eagerness of male. + +Bats, scent-glands; +sexual differences in the colour of; +fur of male frugivorous. + +Battle, law of; +among beetles; +among birds; +among mammals; +in man. + +Beak, sexual difference in the forms of the; +in the colour of the. + +Beaks, of birds, bright colours of. + +Beard, development of, in man; +analogy of the, in man and the quadrumana; +variation of the development of the, in different races of men; +estimation of, among bearded nations; +probable origin of the. + +Beard, in monkeys; +of mammals. + +Beautiful, taste for the, in birds; +in the quadrumana. + +Beauty, sense of, in animals; +appreciation of, by birds; +influence of; +variability of the standard of. + +Beauty, sense of, sufficiently permanent for action of sexual selection. + +Beaven, Lieut., on the development of the horns in Cervus Eldi. + +Beaver, instinct and intelligence of the; +voice of the; +castoreum of the. + +Beavers, battles of male. + +Bechstein, on female birds choosing the best singers among the males; +on rivalry in song-birds; +on the singing of female birds; +on birds acquiring the songs of other birds; +on pairing the canary and siskin; +on a sub-variety of the monk pigeon; +on spurred hens. + +Beddoe, Dr., on causes of difference in stature. + +Bee-eater. + +Bees, pollen-baskets and stings of; +destruction of drones and queens by; +female, secondary sexual characters of; +proportion of sexes; +difference of the sexes in colour and sexual selection. + +Beetle, luminous larva of a. + +Beetles, size of the cerebral ganglia in; +dilatation of the foretarsi in male; +blind; +stridulation of. + +Belgium, ancient inhabitants of. + +Bell, Sir C., on emotional muscles in man; +"snarling muscles;" +on the hand. + +Bell, T., on the numerical proportion of the sexes in moles; +on the newts; +on the croaking of the frog; +on the difference in the coloration of the sexes in Zootoca vivipara; +on moles fighting. + +Bell-bird, sexual difference in the colour of the. + +Bell-birds, colours of. + +Belt, Mr., on the nakedness of tropical mankind; +on a spider-monkey and eagle; +habits of ants; +Lampridae distasteful to mammals; +mimicry of Leptalides; +colours of Nicaraguan frogs; +display of humming-birds; +on the toucans; +protective colouring of skunk. + +Benevolence, manifested by birds. + +Bennett, A.W., attachment of mated birds; +on the habits of Dromaeus irroratus. + +Bennett, Dr., on birds of paradise. + +Berbers, fertility of crosses with other races. + +Bernicla antarctica, colours of. + +Bernicle gander pairing with a Canada goose. + +Bert, M., crustaceans distinguish colours. + +Bettoni, E., on local differences in the nests of Italian birds. + +Beyle, M., see Bombet. + +Bhoteas, colour of the beard in. + +Bhringa, disc-formed tail-feathers of. + +Bianconi, Prof., on structures as explained through mechanical principles. + +Bibio, sexual differences in the genus. + +Bichat, on beauty. + +Bickes, proportion of sexes in man. + +Bile, coloured, in many animals. + +Bimana. + +Birds, imitations of the songs of other birds by; +dreaming; +killed by telegraph wires; +language of; +sense of beauty in; +pleasure of, in incubation; +male, incubation by; +and reptiles, alliance of; +sexual differences in the beak of some; +migratory, arrival of the male before the female; +apparent relation between polygamy and marked sexual differences in; +monogamous, becoming polygamous under domestication; +eagerness of male in pursuit of the female; +wild, numerical proportion of the sexes in; +secondary sexual characters of; +difference of size in the sexes of; +fights of male, witnessed by females; +display of male, to captivate the females; +close attention of, to the songs of others; +acquiring the song of their foster-parents; +brilliant, rarely good songsters; +love-antics and dances of; +coloration of; +moulting of; +unpaired; +male, singing out of season; +mutual affection of; +in confinement, distinguish persons; +hybrid, production of; +Albino; +European, number of species of; +variability of; +geographical distribution of colouring; +gradation of secondary sexual characters in; +obscurely coloured, building concealed nests; +young female, acquiring male characters; +breeding in immature plumage; +moulting of; +aquatic, frequency of white plumage in; +vocal courtship of; +naked skin of the head and neck in. + +Birgus latro, habits of. + +Birkbeck, Mr., on the finding of new mates by golden eagles. + +Birthplace of man. + +Births, numerical proportions of the sexes in, in animals and man; +male and female, numerical proportion of, in England. + +Bischoff, Prof., on the agreement between the brains of man and of the +orang; +figure of the embryo of the dog; +on the convolutions of the brain in the human foetus; +on the difference between the skulls of man and the quadrumana; +resemblance between the ape's and man's. + +Bishop, J., on the vocal organs of frogs; +on the vocal organs of cervine birds; +on the trachea of the Merganser. + +Bison, American, co-operation of; +mane of the male. + +Bitterns, dwarf, coloration of the sexes of. + +Biziura lobata, musky odour of the male; +large size of male. + +Blackbird, sexual differences in the; +proportion of the sexes in the; +acquisition of a song by; +colour of the beak in the sexes of the; +pairing with a thrush; +colours and nidification of the; +young of the; +sexual difference in coloration of the. + +Black-buck, Indian, sexual difference in the colour of the. + +Blackcap, arrival of the male, before the female; +young of the. + +Black-cock, polygamous; +proportion of the sexes in the; +pugnacity and love-dance of the; +call of the; +moulting of the; +duration of the courtship of the; +and pheasant, hybrids of; +sexual difference in coloration of the; +crimson eye-cere of the. + +Black-grouse, characters of young. + +Blacklock, Dr., on music. + +Blackwall, J., on the speaking of the magpie; +on the desertion of their young by swallows; +on the superior activity of male spiders; +on the proportion of the sexes in spiders; +on sexual variation of colour in spiders; +on male spiders. + +Bladder-nose Seal, hood of the. + +Blaine, on the affections of dogs. + +Blair, Dr., on the relative liability of Europeans to yellow fever. + +Blake, C.C., on the jaw from La Naulette. + +Blakiston, Captain, on the American snipe; +on the dances of Tetrao phasianellus. + +Blasius, Dr., on the species of European birds. + +Bledius taurus, hornlike processes of male. + +Bleeding, tendency to profuse. + +Blenkiron, Mr., on sexual preference in horses. + +Blennies, crest developed on the head of male, during the breeding season. + +Blethisa multipunctata, stridulation of. + +Bloch, on the proportions of the sexes in fishes. + +Blood, arterial, red colour of. + +Blood pheasant, number of spurs in. + +Blow-fly, sounds made by. + +Bluebreast, red-throated, sexual differences of the. + +Blumenbach, on Man; +on the large size of the nasal cavities in American aborigines; +on the position of man; +on the number of species of man. + +Blyth, E., on the structure of the hand in the species of Hylobates; +observations on Indian crows; +on the development of the horns in the Koodoo and Eland antelopes; +on the pugnacity of the males of Gallicrex cristatus; +on the presence of spurs in the female Euplocamus erythrophthalmus; +on the pugnacity of the amadavat; +on the spoonbill; +on the moulting of Anthus; +on the moulting of bustards, plovers, and Gallus bankiva; +on the Indian honey-buzzard; +on sexual differences in the colour of the eyes of hornbills; +on Oriolus melanocephalus; +on Palaeornis javanicus; +on the genus Ardetta; +on the peregrine falcon; +on young female birds acquiring male characters; +on the immature plumage of birds; +on representative species of birds; +on the young of Turnix; +on anomalous young of Lanius rufus and Colymbus glacialis; +on the sexes and young of the sparrows; +on dimorphism in some herons; +on the ascertainment of the sex of nestling bullfinches by pulling out +breast-feathers; +on orioles breeding in immature plumage; +on the sexes and young of Buphus and Anastomus; +on the young of the blackcap and blackbird; +on the young of the stonechat; +on the white plumage of Anastomus; +on the horns of Bovine animals; +on the horns of Antilope bezoartica; +on the mode of fighting of Ovis cycloceros; +on the voice of the Gibbons; +on the crest of the male wild goat; +on the colours of Portax picta; +on the colours of Antilope bezoartica; +on the colour of the Axis deer; +on sexual difference of colour in Hylobates hoolock; +on the hog-deer; +on the beard and whiskers in a monkey, becoming white with age. + +Boar, wild, polygamous in India; +use of the tusks by the; +fighting of. + +Boardman, Mr., Albino birds in U.S. + +Boitard and Corbie, MM., on the transmission of sexual peculiarities in +pigeons; +on the antipathy shewn by some female pigeons to certain males. + +Bold, Mr., on the singing of a sterile hybrid canary. + +Bombet, on the variability of the standard of beauty in Europe. + +Bombus, difference of the sexes in. + +Bombycidae, coloration of; +pairing of the; +colours of. + +Bombycilla carolinensis, red appendages of. + +Bombyx cynthia, proportion of the sexes in; +pairing of. + +Bombyx mori, difference of size of the male and female cocoons of; +pairing of. + +Bombyx Pernyi, proportion of sexes of. + +Bombyx Yamamai, M. Personnat on; +proportion of sexes of. + +Bonaparte, C.L., on the call-notes of the wild turkey. + +Bond, F., on the finding of new mates by crows. + +Bone, implements of, skill displayed in making. + +Boner, C., on the transfer of male characters to an old female chamois; +on the habits of stags; +on the pairing of red deer. + +Bones, increase of, in length and thickness, when carrying a greater +weight. + +Bonizzi, P., difference of colour in sexes of pigeons. + +Bonnet monkey. + +Bonwick, J., extinction of Tasmanians. + +Boomerang. + +Boreus hyemalis, scarcity of the male. + +Bory St. Vincent, on the number of species of man; +on the colours of Labrus pavo. + +Bos etruscus. + +Bos gaurus, horns of. + +Bos moschatus. + +Bos primigenius. + +Bos sondaicus, horns of, +colours of. + +Botocudos, mode of life of; +disfigurement of the ears and lower lip of the. + +Boucher de Perthes, J.C. de, on the antiquity of man. + +Bourbon, proportion of the sexes in a species of Papilio from. + +Bourien on the marriage-customs of the savages of the Malay Archipelago. + +Bovidae, dewlaps of. + +Bower-birds, habits of the; +ornamented playing-places of. + +Bows, use of. + +Brachycephalic structure, possible explanation of. + +Brachyura. + +Brachyurus calvus, scarlet face of. + +Bradley, Mr., abductor ossis metatarsi quinti in man. + +Brain, of man, agreement of the, with that of lower animals; +convolutions of, in the human foetus; +influence of development of mental faculties upon the size of the; +influence of the development of on the spinal column and skull; +larger in some existing mammals than in their tertiary prototypes; +relation of the development of the, to the progress of language; +disease of the, affecting speech; +difference in the convolutions of, in different races of men; +supplement on, by Prof. Huxley; +development of the gyri and sulci. + +Brakenridge, Dr., on the influence of climate. + +Brandt, A., on hairy men. + +Braubach, Prof., on the quasi-religious feeling of a dog towards his +master; +on the self-restraint of dogs. + +Brauer, F., on dimorphism in Neurothemis. + +Brazil, skulls found in caves of; +population of; +compression of the nose by the natives of. + +Break between man and the apes. + +Bream, proportion of the sexes in the. + +Breeding, age of, in birds. + +Breeding season, sexual characters making their appearance in the, in +birds. + +Brehm, on the effects of intoxicating liquors on monkeys; +on the recognition of women by male Cynocephali; +on the diversity of the mental faculties of monkeys; +on the habits of baboons; +on revenge taken by monkeys; +on manifestations of maternal affection by monkeys and baboons; +on the instinctive dread of monkeys for serpents; +on the use of stones as missiles by baboons; +on a baboon using a mat for shelter from the sun; +on the signal-cries of monkeys; +on sentinels posted by monkeys; +on co-operation of animals; +on an eagle attacking a young Cercopithecus; +on baboons in confinement protecting one of their number from punishment; +on the habits of baboons when plundering; +on polygamy in Cynocephalus and Cebus; +on the numerical proportion of the sexes in birds; +on the love-dance of the blackcock; +Palamedea cornuta; +on the habits of the Black-grouse; +on sounds produced by birds of paradise; +on assemblages of grouse; +on the finding of new mates by birds; +on the fighting of wild boars; +on sexual differences in Mycetes; +on the habits of Cynocephalus hamadryas. + +Brent, Mr., on the courtship of fowls. + +Breslau, numerical proportion of male and female births in. + +Bridgeman, Laura. + +Brimstone butterfly, sexual difference of colour in the. + +British, ancient, tattooing practised by. + +Broca, Prof., on the occurrence of the supra-condyloid foramen in the human +humerus; +anthropomorphous apes more bipedal than quadrupedal; +on the capacity of Parisian skulls at different periods; +comparison of modern and mediaeval skulls; +on tails of quadrupeds; +on the influence of natural selection; +on hybridity in man; +on human remains from Les Eyzies; +on the cause of the difference between Europeans and Hindoos. + +Brodie, Sir B., on the origin of the moral sense in man. + +Bronn, H.G., on the copulation of insects of distinct species. + +Bronze period, men of, in Europe. + +Brown, R., sentinels of seals generally females; +on the battles of seals; +on the narwhal; +on the occasional absence of the tusks in the female walrus; +on the bladder-nose seal; +on the colours of the sexes in Phoca Groenlandica; +on the appreciation of music by seals; +on plants used as love-philters, by North American women. + +Browne, Dr. Crichton, injury to infants during parturition. + +Brown-Sequard, Dr., on the inheritance of the effects of operations by +guinea-pig. + +Bruce, on the use of the elephant's tusks. + +Brulerie, P. de la, on the habits of Ateuchus cicatricosus; +on the stridulation of Ateuchus. + +Brunnich, on the pied ravens of the Feroe islands. + +Bryant, Dr., preference of tame pigeon for wild mate. + +Bryant, Captain, on the courtship of Callorhinus ursinus. + +Bubas bison, thoracic projection of. + +Bubalus caffer, use of horns. + +Bucephalus capensis, difference of the sexes of, in colour. + +Buceros, nidification and incubation of. + +Buceros bicornis, sexual differences in the colouring of the casque, beak, +and mouth in. + +Buceros corrugatus, sexual differences in the beak of. + +Buchner, L., on the origin of man; +on the use of the human foot as a prehensile organ; +on the mode of progression of the apes; +on want of self-consciousness, etc., in savages. + +Bucholz, Dr., quarrels of chamaeleons. + +Buckinghamshire, numerical proportion of male and female births in. + +Buckland, F., on the numerical proportion of the sexes in rats; +on the proportion of the sexes in the trout; +on Chimaera monstrosa. + +Buckland, W., on the complexity of crinoids. + +Buckler, W., proportion of sexes of Lepidoptera reared by. + +Bucorax abyssinicus, inflation of the neck-wattle of the male during +courtship. + +Budytes Raii. + +Buffalo, Cape. + +Buffalo, Indian, horns of the. + +Buffalo, Italian, mode of fighting of the. + +Buffon, on the number of species of man. + +Bufo sikimmensis. + +Bugs. + +Buist, R., on the proportion of the sexes in salmon; +on the pugnacity of the male salmon. + +Bulbul, pugnacity of the male; +display of under tail-coverts by the male. + +Bull, mode of fighting of the; +curled frontal hair of the. + +Buller, Dr., on the Huia; +the attachment of birds. + +Bullfinch, sexual differences in the; +piping; +female, singing of the; +courtship of the; +widowed, finding a new mate; +attacking a reed-bunting; +nestling, sex ascertained by pulling out breast feathers. + +Bullfinches, distinguishing persons; +rivalry of female. + +Bulls, two young, attacking an old one; +wild, battles of. + +Bull-trout, male, colouring of, during the breeding season. + +Bunting, reed, head feathers of the male; +attacked by a bullfinch. + +Buntings, characters of young. + +Buphus coromandus, sexes and young of; +change of colour in. + +Burchell, Dr., on the zebra; +on the extravagance of a Bushwoman in adorning herself; +celibacy unknown among the savages of South Africa; +on the marriage-customs of the Bushwomen. + +Burke, on the number of species of man. + +Burmese, colour of the beard in. + +Burton, Captain, on negro ideas of female beauty; +on a universal ideal of beauty. + +Bushmen, marriage among. + +Bushwoman, extravagant ornamentation of a. + +Bushwomen, hair of; +marriage-customs of. + +Bustard, throat-pouch of the male; +humming noise produced by a male; +Indian, ear-tufts of. + +Bustards, occurrence of sexual differences and of polygamy among the; +love-gestures of the male; +double moult in. + +Butler, A.G., on sexual differences in the wings of Aricoris epitus; +courtship of butterflies; +on the colouring of the sexes in species of Thecla; +on the resemblance of Iphias glaucippe to a leaf; +on the rejection of certain moths and caterpillars by lizards and frogs. + +Butterfly, noise produced by a; +Emperor; +meadow brown, instability of the ocellated spots of. + +Butterflies, proportion of the sexes in; +forelegs atrophied in some males; +sexual difference in the neuration of the wings of; +pugnacity of male; +protective resemblances of the lower surface of; +display of the wings by; +white, alighting upon bits of paper; +attracted by a dead specimen of the same species; +courtship of; +male and female, inhabiting different stations. + +Buxton, C., observations on macaws; +on an instance of benevolence in a parrot. + +Buzzard, Indian honey-; +variation in the crest of. + +Cabbage butterflies. + +Cachalot, large head of the male. + +Cadences, musical, perception of, by animals. + +Caecum, large, in the early progenitors of man. + +Cairina moschata, pugnacity of the male. + +Californian Indians, decrease of. + +Callianassa, chelae of, figured. + +Callidryas, colours of sexes. + +Callionymus lyra, characters of the male. + +Callorhinus ursinus, relative size of the sexes of; +courtship of. + +Calotes maria. + +Calotes nigrilabris, sexual difference in the colour of. + +Cambridge, O. Pickard, on the sexes of spiders; +on the size of male Nephila. + +Camel, canine teeth of male. + +Campbell, J., on the Indian elephant; +on the proportion of male and female births in the harems of Siam. + +Campylopterus hemileucurus. + +Canaries distinguishing persons. + +Canary, polygamy of the; +change of plumage in, after moulting; +female, selecting the best singing male; +sterile hybrid, singing of a; +female, singing of the; +selecting a greenfinch; +and siskin, pairing of. + +Cancer pagurus. + +Canestrini, G., on rudimentary characters and the origin of man; +on rudimentary characters; +on the movement of the ear in man; +of the variability of the vermiform appendage in man; +on the abnormal division of the malar bone in man; +on abnormal conditions of the human uterus; +on the persistence of the frontal suture in man; +on the proportion of the sexes in silk-moths; +secondary sexual characters of spiders. + +Canfield, Dr., on the horns of the Antilocapra. + +Canine teeth in man, diminution of, in man; +diminution of, in horses; +disappearance of, in male ruminants; +large in the early progenitors of man. + +Canines, and horns, inverse development of. + +Canoes, use of. + +Cantharis, difference of colour in the sexes of a species of. + +Cantharus lineatus. + +Capercailzie, polygamous; +proportion of the sexes in the; +pugnacity of the male; +pairing of the; +autumn meetings of the; +call of the; +duration of the courtship of; +behaviour of the female; +inconvenience of black colour to the female; +sexual difference in the coloration of the; +crimson eye-cere of the male. + +Capitonidae, colours and nidification of the. + +Capra aegagrus, crest of the male; +sexual difference in the colour of. + +Capreolus Sibiricus subecaudatus. + +Caprice, common to man and animals. + +Caprimulgus, noise made by the males of some species of, with their wings. + +Caprimulgus virginianus, pairing of. + +Carabidae. + +Carbonnier, on the natural history of the pike; +on the relative size of the sexes in fishes; +courtship of Chinese Macropus. + +Carcineutes, sexual difference of colour in. + +Carcinus moenas. + +Cardinalis virginianus. + +Carduelis elegans, sexual differences of the beak in. + +Carnivora, marine, polygamous habits of; +sexual differences in the colours of. + +Carp, numerical proportion of the sexes in the. + +Carr, R., on the peewit. + +Carrier pigeon, late development of the wattle in the. + +Carrion beetles, stridulation of. + +Carrion-hawk, bright coloured female of. + +Carus, Prof. V., on the development of the horns in merino sheep; +on antlers of red deer. + +Cassowary, sexes and incubation of the. + +Castnia, mode of holding wings. + +Castoreum. + +Castration, effects of. + +Casuarius galeatus. + +Cat, convoluted body in the extremity of the tail of a; +sick, sympathy of a dog with a. + +Cataract in Cebus Azarae. + +Catarrh, liability of Cebus Azarae to. + +Catarrhine monkeys. + +Caterpillars, bright colours of. + +Cathartes aura. + +Cathartes jota, love-gestures of the male. + +Catlin, G., correlation of colour and texture of hair in the Mandans; +on the development of the beard among the North American Indians; +on the great length of the hair in some North American tribes. + +Caton, J.D., on the development of the horns in Cervus virginianus and +strongyloceros; +on the wild turkey; +on the presence of traces of horns in the female wapiti; +on the fighting of deer; +on the crest of the male wapiti; +on the colours of the Virginian deer; +on sexual differences of colour in the wapiti; +on the spots of the Virginian deer. + +Cats, dreaming; +tortoise-shell; +enticed by valerian; +colours of. + +Cattle, rapid increase of, in South America; +domestic, lighter in winter in Siberia; +horns of; +domestic, sexual differences of, late developed; +numerical proportion of the sexes in. + +Caudal vertebrae, number of, in macaques and baboons; +basal, of monkeys, imbedded in the body. + +Cavolini, observations on Serranus. + +Cebus, maternal affection in a; +gradation of species of. + +Cebus Apella. + +Cebus Azarae, liability of, to the same diseases as man; +distinct sounds produced by; +early maturity of the female. + +Cebus capucinus, polygamous; +sexual differences of colour in; +hair on the head of. + +Cebus vellerosus, hair on the head of. + +Cecidomyiidae, proportions of the sexes in. + +Celibacy, unknown among the savages of South Africa and South America. + +Centipedes. + +Cephalopoda, absence of secondary sexual characters in. + +Cephalopterus ornatus. + +Cephalopterus penduliger. + +Cerambyx heros, stridulant organ of. + +Ceratodus, paddle of. + +Ceratophora aspera, nasal appendages of. + +Ceratophora Stoddartii, nasal horn of. + +Cerceris, habits of. + +Cercocebus aethiops, whiskers, etc., of. + +Cercopithecus, young, seized by an eagle and rescued by the troop; +definition of species of. + +Cercopithecus cephus, sexual difference of colour in. + +Cercopithecus cynosurus and griseo-viridis, colour of the scrotum in. + +Cercopithecus Diana, sexual differences of colour in. + +Cercopithecus griseo-viridis. + +Cercopithecus petaurista, whiskers, etc., of. + +Ceres, of birds, bright colours of. + +Ceriornis Temminckii, swelling of the wattles of the male during courtship. + +Cervulus, weapons of. + +Cervulus moschatus, rudimentary horns of the female. + +Cervus alces. + +Cervus campestris, odour of. + +Cervus canadensis, traces of horns in the female; +attacking a man; +sexual difference in the colour of. + +Cervus elaphus, battles of male; +horns of, with numerous points; +long hairs on the throat of. + +Cervus Eldi. + +Cervus mantchuricus. + +Cervus paludosus, colours of. + +Cervus strongyloceros. + +Cervus virginianus, horns of, in course of modification. + +Ceryle, male black-belted in some species of. + +Cetacea, nakedness of. + +Ceylon, frequent absence of beard in the natives of. + +Chaffinch, proportion of the sexes in the; +courtship of the. + +Chaffinches, new mates found by. + +Chalcophaps indicus, characters of young. + +Chalcosoma atlas, sexual differences of. + +Chamaeleo, sexual differences in the genus; +combats of. + +Chamaeleo bifurcus. + +Chamaeleo Owenii. + +Chamaeleo pumilus. + +Chamaepetes unicolor, modified wing-feather in the male. + +Chameleons. + +Chamois, danger-signals of; +transfer of male characters to an old female. + +Champneys, Mr., acromio-basilar muscle and quadrupedal gait. + +Chapman, Dr., on stridulation in Scolytus. + +Chapuis, Dr., on the transmission of sexual peculiarities in pigeons; +on streaked Belgian pigeons. + +Char, male, colouring of, during the breeding season. + +Characters, male, developed in females; +secondary sexual, transmitted through both sexes; +natural, artificial, exaggeration of, by man. + +Charadrus hiaticula and pluvialis, sexes and young of. + +Chardin on the Persians. + +Charms, worn by women. + +Charruas, freedom of divorce among the. + +Chasmorhynchus, difference of colour in the sexes of; +colours of. + +Chasmorhynchus niveus. + +Chasmorhynchus nudicollis. + +Chasmorhynchus tricarunculatus. + +Chastity, early estimation of. + +Chatterers, sexual differences in. + +Cheever, Rev. H.T., census of the Sandwich Islands. + +Cheiroptera, absence of secondary sexual characters in. + +Chelae of crustacea. + +Chelonia, sexual differences in. + +Chenalopex aegyuptiacus, wing-knobs of. + +Chera progne. + +Chest, proportions of, in soldiers and sailors; +large, of the Quechua and Aymara Indians. + +Chevrotains, canine teeth of. + +Chiasognathus, stridulation of. + +Chiasognathus Grantii, mandibles of. + +Children, legitimate and illegitimate, proportion of the sexes in. + +Chiloe, lice of the natives of; +population of. + +Chimaera monstrosa, bony process on the head of the male. + +Chimaeroid fishes, prehensile organs of male. + +Chimpanzee, ears of the; +representatives of the eyebrows in the; +hands of the; +absence of mastoid processes in the; +platforms built by the; +cracking nuts with a stone; +direction of the hair on the arms of the; +supposed evolution of the; +polygamous and social habits of the. + +China, North, idea of female beauty in. + +China, Southern, inhabitants of. + +Chinese, use of flint tools by the; +difficulty of distinguishing the races of the; +colour of the beard in; +general beardlessness of the; +opinions of the, on the appearance of Europeans and Cingalese; +compression of the feet of. + +Chinsurdi, his opinion of beards. + +Chlamydera maculata. + +Chloeon, pedunculated eyes of the male of. + +Chloephaga, coloration of the sexes in. + +Chlorocoelus Tanana. + +Chorda dorsalis. + +Chough, red beak of the. + +Chromidae, frontal protuberance in male; +sexual differences in colour of. + +Chrysemys picta, long claws of the male. + +Chrysococcyx, characters of young of. + +Chrysomelidae, stridulation of. + +Cicada pruinosa. + +Cicada septendecim. + +Cicadae, songs of the; +rudimentary sound-organs in females of. + +Cicatrix of a burn, causing modification of the facial bones. + +Cichla, frontal protuberance of male. + +Cimetiere du Sud, Paris. + +Cincloramphus cruralis, large size of male. + +Cinclus aquaticus. + +Cingalese, Chinese opinion of the appearance of the. + +Cirripedes, complemental males of. + +Civilisation, effects of, upon natural selection; +influence of, in the competition of nations. + +Clanging of geese, etc. + +Claparede, E., on natural selection applied to man. + +Clarke, on the marriage-customs of Kalmucks. + +Classification. + +Claus, C., on the sexes of Saphirina. + +Cleft-palate, inherited. + +Climacteris erythrops, sexes of. + +Climate, cool, favourable to human progress; +power of supporting extremes of, by man; +want of connexion of, with colour; +direct action of, on colours of birds. + +Cloaca, existence of a, in the early progenitors of man. + +Cloacal passage existing in the human embryo. + +Clubs, used as weapons before dispersion of mankind. + +Clucking of fowls. + +Clythra 4-punctata, stridulation of. + +Coan, Mr., Sandwich-islanders. + +Cobbe, Miss, on morality in hypothetical bee-community. + +Cobra, ingenuity of a. + +Coccus. + +Coccyx, in the human embryo; +convoluted body at the extremity of the; +imbedded in the body. + +Cochin-China, notions of beauty of the inhabitants of. + +Cock, blind, fed by its companion; +game, killing a kite; +comb and wattles of the; +preference shewn by the, for young hens; +game, transparent zone in the hackles of a. + +Cock of the rock. + +Cockatoos, nestling; +black, immature plumage of. + +Coelenterata, absence of secondary sexual characters in. + +Coffee, fondness of monkeys for. + +Cold, supposed effects of; +power of supporting, by man. + +Coleoptera, stridulation of; +stridulant organs of, discussed. + +Colias edusa and hyale. + +Collingwood, C., on the pugnacity of the butterflies of Borneo; +on butterflies being attracted by a dead specimen of the same species. + +Colobus, absence of the thumb. + +Colombia, flattened heads of savages of. + +Colonists, success of the English as. + +Coloration, protective, in birds. + +Colour, supposed to be dependent on light and heat; +correlation of, with immunity from certain poisons and parasites; +purpose of, in lepidoptera; +relation of, to sexual functions, in fishes; +difference of, in the sexes of snakes; +sexual differences of, in lizards; +influence of, in the pairing of birds of different species; +relation of, to nidification; +sexual differences of, in mammals; +recognition of, by quadrupeds; +of children, in different races of man; +of the skin in man. + +Colours, admired alike by man and animals; +bright, due to sexual selection; +bright, among the lower animals; +bright, protective to butterflies and moths; +bright, in male fishes; +transmission of, in birds. + +Colquhoun, example of reasoning in a retriever. + +Columba passerina, young of. + +Colymbus glacialis, anomalous young of. + +Comb, development of, in fowls. + +Combs and wattles in male birds. + +Community, preservation of variations useful to the, by natural selection. + +Complexion, different in men and women, in an African tribe. + +Compositae, gradation of species among the. + +Comte, C., on the expression of the ideal of beauty by sculpture. + +Conditions of life, action of changed, upon man; +influence of, on plumage of birds. + +Condor, eyes and comb of the. + +Conjugations, origin of. + +Conscience, absence of, in some criminals. + +Constitution, difference of, in different races of men. + +Consumption, liability of Cebus Azarae to; +connection between complexion and. + +Convergence of characters. + +Cooing of pigeons and doves. + +Cook, Captain, on the nobles of the Sandwich Islands. + +Cope, E.D., on the Dinosauria. + +Cophotis ceylanica, sexual differences of. + +Copris. + +Copris Isidis, sexual differences of. + +Copris lunaris, stridulation of. + +Corals, bright colours of. + +Coral-snakes. + +Cordylus, sexual difference of colour in a species of. + +Corfu, habits of the Chaffinch in. + +Cornelius, on the proportions of the sexes in Lucanus Cervus. + +Corpora Wolffiana, agreement of, with the kidneys of fishes. + +Correlated variation. + +Correlation, influence of, in the production of races. + +Corse, on the mode of fighting of the elephant. + +Corvus corone. + +Corvus graculus, red beak of. + +Corvus pica, nuptial assembly of. + +Corydalis cornutus, large jaws of the male. + +Cosmetornis. + +Cosmetornis vexillarius, elongation of wing-feathers in. + +Cotingidae, sexual differences in; +coloration of the sexes of; +resemblance of the females of distinct species of. + +Cottus scorpius, sexual differences in. + +Coulter, Dr., on the Californian Indians. + +Counting, origin of; +limited power of, in primeval man. + +Courage, variability of, in the same species; +universal high appreciation of; +importance of; +characteristic of men. + +Courtship, greater eagerness of males in; +of fishes; +of birds. + +Cow, winter change of colour. + +Crab, devil. + +Crab, shore, habits of. + +Crabro cribrarius, dilated tibiae of the male. + +Crabs, proportions of the sexes in. + +Cranz, on the inheritance of dexterity in seal-catching. + +Crawfurd, on the number of species of man. + +Crenilabrus massa and C. melops, nests, built by. + +Crest, origin of, in Polish fowls. + +Crests, of birds, difference of, in the sexes; +dorsal hairy, of mammals. + +Cricket, field-, stridulation of the; +pugnacity of male. + +Cricket, house-, stridulation of the. + +Crickets, sexual differences in. + +Crinoids, complexity of. + +Crioceridae, stridulation of the. + +Croaking of frogs. + +Crocodiles, musky odour of, during the breeding season. + +Crocodilia. + +Crossbills, characters of young. + +Crosses in man. + +Crossing of races, effects of the. + +Crossoptilon auritum, adornment of both sexes of; +sexes alike in. + +Crotch, G.R., on the stridulation of beetles; +on the stridulation of Heliopathes; +on the stridulation of Acalles; +habit of female deer at breeding time. + +Crow, Indians, long hair of the. + +Crow, young of the. + +Crows, vocal organs of the; +living in triplets. + +Crows, carrion, new mates found by. + +Crows, Indian, feeding their blind companions. + +Cruelty of savages to animals. + +Crustacea, parasitic, loss of limbs by female; +prehensile feet and antennae of; +male, more active than female; +parthenogenesis in; +secondary sexual characters of; +amphipod, males sexually mature while young; +auditory hairs of. + +Crystal worn in the lower lip by some Central African women. + +Cuckoo fowls. + +Culicidae, attracted by each other's humming. + +Cullen, Dr., on the throat-pouch of the male bustard. + +Cultivation of plants, probable origin of. + +Cupples, Mr., on the numerical proportion of the sexes in dogs, sheep, and +cattle; +on the Scotch deerhound; +on sexual preference in dogs. + +Curculionidae, sexual difference in length of snout in some; +hornlike processes in male; +musical. + +Curiosity, manifestations of, by animals. + +Curlews, double moult in. + +Cursores, comparative absence of sexual differences among the. + +Curtis, J., on the proportion of the sexes in Athalia. + +Cuvier, F., on the recognition of women by male quadrumana. + +Cuvier, G., on the number of caudal vertebrae in the mandrill; +on instinct and intelligence; +views of, as to the position of man; +on the position of the seals; +on Hectocotyle. + +Cyanalcyon, sexual difference in colours of; +immature plumage of. + +Cyanecula suecica, sexual differences of. + +Cychrus, sounds produced by. + +Cycnia mendica, sexual difference of, in colour. + +Cygnus ferus, trachea of. + +Cygnus immutabilis. + +Cygnus olor, white young of. + +Cyllo Leda, instability of the ocellated spots of. + +Cynanthus, variation in the genus. + +Cynipidae, proportion of the sexes in. + +Cynocephalus, difference of the young from the adult; +male, recognition of women by; +polygamous habits of species of. + +Cynocephalus babouin. + +Cynocephalus chacma. + +Cynocephalus gelada. + +Cynocephalus hamadryas, sexual difference of colour in. + +Cynocephalus leucophaeus, colours of the sexes of. + +Cynocephalus mormon, colours of the male. + +Cynocephalus porcarius, mane of the male. + +Cynocephalus sphinx. + +Cynopithecus niger, ear of. + +Cypridina, proportions of the sexes in. + +Cyprinidae, proportion of the sexes in the. + +Cyprinidae, Indian. + +Cyprinodontidae, sexual differences in the. + +Cyprinus auratus. + +Cypris, relation of the sexes in. + +Cyrtodactylus rubidus. + +Cystophora cristata, hood of. + +Dacelo, sexual difference of colour in. + +Dacelo Gaudichaudi, young male of. + +Dal-ripa, a kind of ptarmigan. + +Damalis albifrons, peculiar markings of. + +Damalis pygarga, peculiar markings of. + +Dampness of climate, supposed influence of, on the colour of the skin. + +Danaidae. + +Dances of birds. + +Dancing, universality of. + +Danger-signals of animals. + +Daniell, Dr., his experience of residence in West Africa. + +Darfur, protuberances artificially produced by natives of. + +Darwin, F., on the stridulation of Dermestes murinus. + +Dasychira pudibunda, sexual difference of colour in. + +Davis, A.H., on the pugnacity of the male stag-beetle. + +Davis, J.B., on the capacity of the skull in various races of men; +on the beards of the Polynesians. + +Death's Head Sphinx. + +Death-rate higher in towns than in rural districts. + +Death-tick. + +De Candolle, Alph., on a case of inherited power of moving the scalp. + +Declensions, origin of. + +Decoration in birds. + +Decticus. + +Deer, development of the horns in; +spots of young; +horns of; +use of horns of; +horns of a, in course of modification; +size of the horns of; +female, pairing with one male whilst others are fighting for her; +male, attracted by the voice of the female; +male, odour emitted by. + +Deer, Axis, sexual difference in the colour of the. + +Deer, fallow, different coloured herds of. + +Deer, Mantchurian. + +Deer, Virginian, colour of the, not affected by castration; +colours of. + +Deerhound, Scotch, greater size of the male. + +Defensive orders of mammals. + +De Geer, C., on a female spider destroying a male. + +Dekay, Dr., on the bladder-nose seal. + +Delorenzi, G., division of malar bone. + +Demerara, yellow fever in. + +Dendrocygna. + +Dendrophila frontalis, young of. + +Denison, Sir W., manner of ridding themselves of vermin among the +Australians; +extinction of Tasmanians. + +Denny, H., on the lice of domestic animals. + +Dermestes murinus, stridulation of. + +Descent traced through the mother alone. + +Deserts, protective colouring of animals inhabiting. + +Desmarest, on the absence of suborbital pits in Antilope subgutturosa; +on the whiskers of Macacus; +on the colour of the opossum; +on the colours of the sexes of Mus minutus; +on the colouring of the ocelot; +on the colours of seals; +on Antilope caama; +on the colours of goats; +on sexual difference of colour in Ateles marginatus; +on the mandrill; +on Macacus cynomolgus. + +Desmoulins, on the number of species of man; +on the muskdeer. + +Desor, on the imitation of man by monkeys. + +Despine, P., on criminals destitute of conscience. + +Development, embryonic of man; +correlated. + +Devil, not believed in by the Fuegians. + +Devil-crab. + +Devonian, fossil-insect from the. + +Dewlaps, of Cattle and antelopes. + +Diadema, sexual differences of colouring in the species of. + +Diamond-beetles, bright colours of. + +Diastema, occurrence of, in man. + +Diastylidae, proportion of the sexes in. + +Dicrurus, racket-shaped feathers in; +nidification of. + +Dicrurus macrocercus, change of plumage in. + +Didelphis opossum, sexual difference in the colour of. + +Differences, comparative, between different species of birds of the same +sex. + +Digits, supernumerary, more frequent in men than in women; +supernumerary, inheritance of; +supernumerary, early development of. + +Dimorphism, in females of water-beetles; +in Neurothemis and Agrion. + +Diodorus, on the absence of beard in the natives of Ceylon. + +Dipelicus Cantori, sexual differences of. + +Diplopoda, prehensile limbs of the male. + +Dipsas cynodon, sexual difference in the colour of. + +Diptera. + +Disease, generated by the contact of distinct peoples. + +Diseases, common to man and the lower animals; +difference of liability to, in different races of men; +new, effects of, upon savages; +sexually limited. + +Display, coloration of Lepidoptera for; +of plumage by male birds. + +Distribution, wide, of man; +geographical, as evidence of specific distinctness in man. + +Disuse, effects of, in producing rudimentary organs; +and use of parts, effects of; +of parts, influence of, on the races of men. + +Divorce, freedom of, among the Charruas. + +Dixon, E.S., on the pairing of different species of geese; +on the courtship of peafowl. + +Dobrizhoffer, on the marriage-customs of the Abipones. + +Dobson, Dr., on the Cheiroptera; +scent-glands of bats; +frugivorous bats. + +Dogs, suffering from tertian ague; +memory of; +dreaming; +diverging when drawing sledges over thin ice; +exercise of reasoning faculties by; +domestic, progress of, in moral qualities; +distinct tones uttered by; +parallelism between his affection for his master and religious feeling; +sociability of the; +sympathy of, with a sick cat; +sympathy of, with his master; +their possession of conscience; +possible use of the hair on the fore-legs of the; +races of the; +numerical proportion of male and female births in; +sexual affection between individuals of; +howling at certain notes; +rolling in carrion. + +Dolichocephalic structure, possible cause of. + +Dolphins, nakedness of. + +Domestic animals, races of; +change of breeds of. + +Domestication, influence of, in removing the sterility of hybrids. + +D'Orbigny, A., on the influence of dampness and dryness on the colour of +the skin; +on the Yuracaras. + +Dotterel. + +Doubleday, E., on sexual differences in the wings of butterflies. + +Doubleday, H., on the proportion of the sexes in the smaller moths; +males of Lasiocampa quercus and on the attraction of the Saturnia carpini +by the female; +on the proportion of the sexes in the Lepidoptera; +on the ticking of Anobium tesselatum; +on the structure of Ageronia feronia; +on white butterflies alighting upon paper. + +Douglas, J.W., on the sexual differences of the Hemiptera; +colours of British Homoptera. + +Down, of birds. + +Draco, gular appendages of. + +Dragonet, Gemmeous. + +Dragon-flies, caudal appendages of male; +relative size of the sexes of; +difference in the sexes of; +want of pugnacity by the male. + +Drake, breeding plumage of the. + +Dreams, possible source of the belief in spiritual agencies. + +Drill, sexual difference of colour in the. + +Dromaeus irroratus. + +Dromolaea, Saharan species of. + +Drongo shrike. + +Drongos, racket-shaped feathers in the tails of. + +Dryness of climate, supposed influence of, on the colour of the skin. + +Dryopithecus. + +Duck, harlequin, age of mature plumage in the; +breeding in immature plumage. + +Duck, long-tailed, preference of male, for certain females. + +Duck, pintail, pairing with a widgeon. + +Duck, voice of the; +pairing with a shield-drake; +immature plumage of the. + +Duck, wild, sexual differences in the; +speculum and male characters of; +pairing with a pin-tail drake. + +Ducks, wild, becoming polygamous under partial domestication; +dogs and cats recognised by. + +Dufosse, Dr., sounds produced by fish. + +Dugong, nakedness of; +tusks of. + +Dujardin, on the relative size of the cerebral ganglia, in insects. + +Duncan, Dr., on the fertility of early marriages; +comparative health of married and single. + +Dupont, M., on the occurrence of the supra-condyloid foramen in the humerus +of man. + +Durand, J.P., on causes of variation. + +Dureau de la Malle, on the songs of birds; +on the acquisition of an air by blackbirds. + +Dutch, retention of their colour by the, in South Africa. + +Duty, sense of. + +Duvaucel, female Hylobates washing her young. + +Dyaks, pride of, in mere homicide. + +Dynastes, large size of males of. + +Dynastini, stridulation of. + +Dytiscus, dimorphism of females of; +grooved elytra of the female. + +Eagle, young Cercopithecus rescued from, by the troop. + +Eagle, white-headed, breeding in immature plumage. + +Eagles, golden, new mates found by. + +Ear, motion of the; +external shell of the, useless in man; +rudimentary point of the, in man. + +Ears, more variable in men than women; +piercing and ornamentation of the. + +Earwigs, parental feeling in. + +Echidna. + +Echini, bright colours of some. + +Echinodermata, absence of secondary sexual characters in. + +Echis carinata. + +Ecker, figure of the human embryo; +on the development of the gyri and sulci of the brain; +on the sexual differences in the pelvis in man; +on the presence of a sagittal crest in Australians. + +Edentata, former wide range of, in America; +absence of secondary sexual characters in. + +Edolius, racket-shaped feathers in. + +Edwards, Mr., on the proportion of the sexes in North American species of +Papilio. + +Eels, hermaphroditism of. + +Egerton, Sir P., on the use of the antlers of deer; +on the pairing of red deer; +on the bellowing of stags. + +Eggs, hatched by male fishes. + +Egret, Indian, sexes and young of. + +Egrets, breeding plumage of; +white. + +Ehrenberg, on the mane of the male Hamadryas baboon. + +Ekstrom, M., on Harelda glacialis. + +Elachista rufocinerea, habits of male. + +Eland, development of the horns of the. + +Elands, sexual differences of colour in. + +Elaphomyia, sexual differences in. + +Elaphrus uliginosus, stridulation of. + +Elaps. + +Elateridae, proportion of the sexes in. + +Elaters, luminous. + +Elephant, rate of increase of the; +nakedness of the; +using a fan; +Indian, forbearance to his keeper; +polygamous habits of the; +pugnacity of the male; +tusks of; +Indian, mode of fighting of the; +male, odour emitted by the; +attacking white or grey horses. + +Elevation of abode, modifying influence of. + +Elimination of inferior individuals. + +Elk, winter change of the. + +Elk, Irish, horns of the. + +Ellice Islands, beards of the natives. + +Elliot, D.G., on Pelecanus erythrorhynchus. + +Elliot, R., on the numerical proportion of the sexes in young rats; +on the proportion of the sexes in sheep. + +Elliot, Sir W., on the polygamous habits of the Indian wild boar. + +Ellis, on the prevalence of infanticide in Polynesia. + +Elphinstone, Mr., on local difference of stature among the Hindoos; +on the difficulty of distinguishing the native races of India. + +Elytra, of the females of Dytiscus Acilius, Hydroporus. + +Emberiza, characters of young. + +Emberiza miliaria. + +Emberiza schoeniclus, head-feathers of the male. + +Embryo of man; +of the dog. + +Embryos of mammals, resemblance of the. + +Emigration. + +Emotions experienced by the lower animals in common with man; +manifested by animals. + +Emperor butterfly. + +Emperor moth. + +Emu, sexes and incubation of. + +Emulation of singing birds. + +Endurance, estimation of. + +Energy, a characteristic of men. + +England, numerical proportion of male and female births in. + +Engleheart, Mr., on the finding of new mates by starlings. + +English, success of, as colonists. + +Engravers, short-sighted. + +Entomostraca. + +Entozoa, difference of colour between the males and females of some. + +Environment, direct action of the, in causing differences between the +sexes. + +Envy, persistence of. + +Eocene period, possible divergence of men during the. + +Eolidae, colours of, produced by the biliary glands. + +Epeira nigra, small size of the male of. + +Ephemerae. + +Ephemeridae. + +Ephippiger vitium, stridulating organs of. + +Epicalia, sexual differences of colouring in the species of. + +Equus hemionus, winter change of. + +Erateina, coloration of. + +Ercolani, Prof., hermaphroditism in eels. + +Erect attitude of man. + +Eristalis, courting of. + +Eschricht, on the development of hair in man; +on a languinous moustache in a female foetus; +on the want of definition between the scalp and the forehead in some +children; +on the arrangement of the hair in the human foetus; +on the hairiness of the face in the human foetus of both sexes. + +Esmeralda, difference of colour in the sexes of. + +Esox lucius. + +Esox reticulatus. + +Esquimaux, their belief in the inheritance of dexterity in seal-catching; +mode of life of. + +Estrelda amandava, pugnacity of the male. + +Eubagis, sexual differences of colouring in the species of. + +Euchirus longimanus, sound produced by. + +Eudromias morinellus. + +Eulampis jugularis, colours of the female. + +Euler, on the rate of increase in the United States. + +Eunomota superciliaris, racket-shaped feathers in the tail of. + +Eupetomena macroura, colours of the female. + +Euphema splendida. + +Euplocamus erythrophthalmus, possession of spurs by the female. + +Europe, ancient inhabitants of. + +Europeans, difference of, from Hindoos; +hairiness of, probably due to reversion. + +Eurostopodus, sexes of. + +Eurygnathus, different proportions of the head in the sexes of. + +Eustephanus, sexual differences of species of; +young of. + +Exaggeration of natural characters by man. + +Exogamy. + +Experience, acquisition of, by animals. + +Expression, resemblances in, between man and the apes. + +Extinction of races, causes of. + +Eye, destruction of the; +change of position in; +obliquity of, regarded as a beauty by the Chinese and Japanese. + +Eyebrows, elevation of; +development of long hairs in; +in monkeys; +eradicated in parts of South America and Africa; +eradication of, by the Indians of Paraguay. + +Eyelashes, eradication of, by the Indians of Paraguay. + +Eyelids, coloured black, in part of Africa. + +Eyes, pillared, of the male of Chloeon; +difference in the colour of, in the sexes of birds. + +Eyton, T.C., observations on the development of the horns in the fallow +deer. + +Eyzies, Les, human remains from. + +Fabre, M., on the habits of Cerceris. + +Facial bones, causes of modification of the. + +Faculties, diversity of, in the same race of men; +inheritance of; +diversity of, in animals of the same species; +mental variation of, in the same species; +of birds. + +Fakirs, Indian, tortures undergone by. + +Falco leucocephalus. + +Falco peregrinus. + +Falco tinnunclus. + +Falcon, peregrine, new mate found by. + +Falconer, H., on the mode of fighting of the Indian elephant; +on canines in a female deer; +on Hyomoschus aquaticus. + +Falkland Islands, horses of. + +Fallow-deer, different coloured herds of. + +Famines, frequency of, among savages. + +Farr, Dr., on the effects of profligacy; +on the influence of marriage on mortality. + +Farrar, F.W., on the origin of language; +on the crossing or blending of languages; +on the absence of the idea of God in certain races of men; +on early marriages of the poor; +on the middle ages. + +Farre, Dr., on the structure of the uterus. + +Fashions, long prevalence of, among savages. + +Faye, Prof., on the numerical proportion of male and female births in +Norway and Russia; +on the greater mortality of male children at and before birth. + +Feathers, modified, producing sounds; +elongated, in male birds; +racket-shaped; +barbless and with filamentous barbs in certain birds; +shedding of margins of. + +Feeding, high, probable influence of, in the pairing of birds of different +species. + +Feet, thickening of the skin on the soles of the; +modification of, in man. + +Felis canadensis, throat-ruff of. + +Felis pardalis and F. mitis, sexual difference in the colouring of. + +Female, behaviour of the, during courtship. + +Female birds, differences of. + +Females, presence of rudimentary male organs in; +preference of, for certain males; +pursuit of, by males; +occurrence of secondary sexual characters in; +development of male character by. + +Females and males, comparative numbers of; +comparative mortality of, while young. + +Femur and tibia, proportions of, in the Aymara Indians. + +Fenton, Mr., decrease of Maories; +infanticide amongst the Maories. + +Ferguson, Mr., on the courtship of fowls. + +Fertilisation, phenomena of, in plants; +in the lower animals. + +Fertility lessened under changed conditions. + +Fevers, immunity of Negroes and Mulattoes from. + +Fiber zibethicus, protective colouring of it. + +Fick, H., effect of conscription for military service. + +Fidelity, in the elephant; +of savages to one another; +importance of. + +Field-slaves, difference of, from house-slaves. + +Fiji Archipelago, population of the. + +Fiji Islands, beards of the natives; +marriage-customs of the. + +Fijians, burying their old and sick parents alive; +estimation of the beard among the; +admiration of, for a broad occiput. + +Filial affection, partly the result of natural selection. + +Filum terminale. + +Finch, racket-shaped feathers in the tail of a. + +Finches, spring change of colour in; +British, females of the. + +Fingers, partially coherent, in species of Hylobates. + +Finlayson, on the Cochin Chinese. + +Fire, use of. + +Fischer, on the pugnacity of the male of Lethrus cephalotes. + +Fischer, F. Von, on display of brightly coloured parts by monkeys in +courtship. + +Fish, eagerness of male; +proportion of the sexes in; +sounds produced by. + +Fishes, kidneys of, represented by Corpora Wolffiana in the human embryo; +male, hatching ova in their mouths; +receptacles for ova possessed by; +relative size of the sexes in; +fresh-water, of the tropics; +protective resemblances in; +change of colour in; +nest-building; +spawning of; +sounds produced by; +continued growth of. + +Flamingo, age of mature plumage. + +Flexor pollicis longus, similar variation of, in man. + +Flies, humming of. + +Flint tools. + +Flints, difficulty of chipping into form. + +Florida, Quiscalus major in. + +Florisuga mellivora. + +Flounder, coloration of the. + +Flower, W.H., on the abductor of the fifth metatarsal in apes; +on the position of the Seals; +on the Pithecia monachu; +on the throat-pouch of the male bustard. + +Fly-catchers, colours and nidification of. + +Foetus, human, woolly covering of the; +arrangement of the hair on. + +Food, influence of, upon stature. + +Foot, prehensile power of the, retained in some savages; +prehensile, in the early progenitors of man. + +Foramen, supra-condyloid, exceptional occurrence of in the humerus of man; +in the early progenitors of man. + +Forbes, D., on the Aymara Indians; +on local variation of colour in the Quichuas; +on the hairlessness of the Aymaras and Quichuas; +on the long hair of the Aymaras and Quichaus. + +Forel, F., on white young swans. + +Forester, Hon. O.W., on an orphan hawk. + +Formica rufa, size of the cerebral ganglia in. + +Fossils, absence of, connecting man with the apes. + +Fowl, occurrence of spurs in the female; +game, early pugnacity of; +Polish, early development of cranial peculiarities of; +variations in plumage of; +examples of correlated development in the; +domestic, breeds and sub-breeds of. + +Fowls, spangled Hamburg; +inheritance of changes of plumage by; +sexual peculiarities in, transmitted only to the same sex; +loss of secondary sexual characters by male; +Polish, origin of the crest in; +period of inheritance of characters by; +cuckoo-; +development of the comb in; +numerical proportion of the sexes in; +courtship of; +mongrel, between a black Spanish cock and different hens; +pencilled Hamburg, difference of the sexes in; +Spanish, sexual differences of the comb in; +spurred, in both sexes. + +Fox, W.D., on some half-tamed wild ducks becoming polygamous, and on +polygamy in the guinea-fowl and canary-bird; +on the proportion of the sexes in cattle; +on the pugnacity of the peacock; +on a nuptial assembly of magpies; +on the finding of new mates by crows; +on partridges living in triplets; +on the pairing of a goose with a Chinese gander. + +Foxes, wariness of young, in hunting districts; +black. + +Fraser, C., on the different colours of the sexes in a species of Squilla. + +Fraser, G., colours of Thecla. + +Frere, Hookham, quoting Theognis on selection in mankind. + +Fringilla cannabina. + +Fringilla ciris, age of mature plumage in. + +Fringilla cyanea, age of mature plumage in. + +Fringilla leucophrys, young of. + +Fringilla spinus. + +Fringilla tristis, change of colour in, in spring; +young of. + +Fringillidae, resemblance of the females of distinct species of. + +Frog, bright coloured and distasteful to birds. + +Frogs, male; +temporary receptacles for ova possessed by; +ready to breed before the females; +fighting of; +vocal organs of. + +Frontal bone, persistence of the suture in. + +Fruits, poisonous, avoided by animals. + +Fuegians, difference of stature among the; +power of sight in the; +skill of, in stone-throwing; +resistance of the, to their severe climate; +mental capacity of the; +quasi-religious sentiments of the; +resemblance of, in mental characters, to Europeans; +mode of life of the; +aversion of, to hair on the face; +said to admire European women. + +Fulgoridae, songs of the. + +Fur, whiteness of, in Arctic animals in winter. + +Fur-bearing animals, acquired sagacity of. + +Gallicrex, sexual difference in the colour of the irides in. + +Gallicrex cristatus, pugnacity of male; +red carbuncle occurring in the male during the breeding-season. + +Gallinaceae, frequency of polygamous habits and of sexual differences in +the; +love-gestures of; +decomposed feathers in; +stripes of young; +comparative sexual differences between the species of; +plumage of. + +Gallinaceous birds, weapons of the male; +racket-shaped feathers on the heads of. + +Gallinula chloropus, pugnacity of the male. + +Galloperdix, spurs of; +development of spurs in the female. + +Gallophasis, young of. + +Galls. + +Gallus bankiva, neck-hackles of. + +Gallus Stanleyi, pugnacity of the male. + +Galton, Mr., on hereditary genius; +gregariousness and independence in animals; +on the struggle between the social and personal impulses; +on the effects of natural selection on civilised nations; +on the sterility of sole daughters; +on the degree of fertility of people of genius; +on the early marriages of the poor; +on the ancient Greeks; +on the Middle Ages; +on the progress of the United States; +on South African notions of beauty. + +Gammarus, use of the chelae of. + +Gammarus marinus. + +Gannets, white only when mature. + +Ganoid fishes. + +Gaour, horns of the. + +Gap between man and the apes. + +Gaper, sexes and young of. + +Gardner, on an example of rationality in a Gelasimus. + +Garrulus glandarius. + +Gartner, on sterility of hybrid plants. + +Gasteropoda, pulmoniferous, courtship of. + +Gasterosteus, nidification of. + +Gasterosteus leiurus. + +Gasterosteus trachurus. + +Gastrophora, wings of, brightly coloured beneath. + +Gauchos, want of humanity among the. + +Gaudry, M., on a fossil monkey. + +Gavia, seasonal change of plumage in. + +Geese, clanging noise made by; +pairing of different species of; +Canada, selection of mates by. + +Gegenbaur, C., on the number of digits in the Ichthyopterygia; +on the hermaphroditism of the remote progenitors of the vertebrata; +two types of nipple in mammals. + +Gelasimus, proportions of the sexes in a species of; +use of the enlarged chelae of the male; +pugnacity of males of; +rational actions of a; +difference of colour in the sexes of a species of. + +Gemmules, dormant in one sex. + +Genius, hereditary. + +Genius, fertility of men and women of. + +Geoffroy St.-Hilaire, Isid., on the recognition of women by male +quadrumana; +on monstrosities; +coincidences of arrested development with polydactylism; +on animal-like anomalies in the human structure; +on the correlation of monstrosities; +on the distribution of hair in man and monkeys; +on the caudal vertebrae of monkeys; +on correlated variability; +on the classification of man; +on the long hair on the heads of species of Semnopithecus; +on the hair in monkeys; +on the development of horns in female deer; +and F. Cuvier, on the mandrill; +on Hylobates. + +Geographical distribution, as evidence of specific distinctions in man. + +Geometrae, brightly coloured beneath. + +Geophagus, frontal protuberance of, male; +eggs hatched by the male, in the mouth or branchial cavity. + +Georgia, change of colour in Germans settled in. + +Geotrupes, stridulation of. + +Gerbe, M., on the nest-building of Crenilabus massa and C. Melops. + +Gerland, Dr., on the prevalence of infanticide; +on the extinction of races. + +Gervais, P., on the hairiness of the gorilla; +on the mandrill. + +Gesture-language. + +Ghost-moth, sexual difference of colour in the. + +Giard, M., disputes descent of vertebrates from Ascidians; +colour of sponges and Ascidians; +musky odour of Sphinx. + +Gibbon, voice of. + +Gibbon, Hoolock, nose of. + +Gibbs, Sir D., on differences of the voice in different races of men. + +Gill, Dr., male seals larger than females; +sexual differences in seals. + +Giraffe, its mode of using the horns; +mute, except in the rutting season. + +Giraud-Teulon, on the cause of short sight. + +Glanders, communicable to man from the lower animals. + +Glands, odoriferous, in mammals. + +Glareola, double moult in. + +Glomeris limbata, difference of colour in the sexes of. + +Glow-worm, female, apterous; +luminosity of the. + +Gnats, dances of; +auditory powers of. + +Gnu, skeletons of, found locked together; +sexual differences in colour of the. + +Goat, male, wild, falling on his horns; +male, odour emitted by; +male, wild, crest of the; +Berbura, mane, dewlap, etc., of the male; +Kemas, sexual difference in the colour of the. + +Goats, sexual differences in the horns of; +horns of; +mode of fighting of; +domestic, sexual differences of, late developed; +beards of. + +Goatsucker, Virginian, pairing of the. + +Gobies, nidification of. + +God, want of the idea of, in some races of men. + +Godron, M., on variability; +on difference of stature; +on the want of connexion between climate and the colour of the skin; +on the colour of the skin; +on the colour of infants. + +Goldfinch, proportion of the sexes in the; +sexual differences of the beak in the; +courtship of the. + +Goldfinch, North American, young of. + +Goldfish. + +Gomphus, proportions of the sexes in; +difference in the sexes of. + +Gonepteryx Rhamni, sexual difference of colour in. + +Goodsir, Prof., on the affinity of the lancelet to the ascidians. + +Goosander, young of. + +Goose, Antarctic, colours of the. + +Goose, Canada, pairing with a Bernicle gander. + +Goose, Chinese, knob on the beak of the. + +Goose, Egyptian. + +Goose, Sebastopol, plumage of. + +Goose, Snow-, whiteness of the. + +Goose, Spur-winged. + +Gorilla, semi-erect attitude of the; +mastoid processes of the; +protecting himself from rain with his hands; +manner of sitting; +supposed to be a kind of mandrill; +polygamy of the; +voice of the; +cranium of; +fighting of male. + +Gosse, P.H., on the pugnacity of the male Humming-bird. + +Gosse, M., on the inheritance of artificial modifications of the skull. + +Gould, B.A., on variation in the length of the legs in man; +measurements of American soldiers; +on the proportions of the body and capacity of the lungs in different races +of men; +on the inferior vitality of mulattoes. + +Gould, J., on migration of swifts; +on the arrival of male snipes before the females; +on the numerical proportion of the sexes in birds; +on Neomorpha Grypus; +on the species of Eustephanus; +on the Australian musk-duck; +on the relative size of the sexes in Briziura lobata and Cincloramphus +cruralis; +on Lobivanellus lobatus; +on habits of Menura Alberti; +on the rarity of song in brilliant birds; +on Selasphorus platycerus; +on the Bower-birds; +on the ornamental plumage of the Humming-birds; +on the moulting of the ptarmigan; +on the display of plumage by the male Humming-birds; +on the shyness of adorned male birds; +on the decoration of the bowers of Bower-birds; +on the decoration of their nest by Humming-birds; +on variation in the genus Cynanthus; +on the colour of the thighs in a male parrakeet; +on Urosticte Benjamini; +on the nidification of the Orioles; +on obscurely-coloured birds building concealed nests; +on trogons and king-fishers; +on Australian parrots; +on Australian pigeons; +on the moulting of the ptarmigan; +on the immature plumage of birds; +on the Australian species of Turnix; +on the young of Aithurus polytmus; +on the colours of the bills of toucans; +on the relative size of the sexes in the marsupials of Australia; +on the colours of the Marsupials. + +Goureaux, on the stridulation of Mutilla europaea. + +Gout, sexually transmitted. + +Graba, on the Pied Ravens of the Feroe Islands; +variety of the Guillemot. + +Gradation of secondary sexual characters in birds. + +Grallatores, absence of secondary sexual characters in; +double moult in some. + +Grallina, nidification of. + +Grasshoppers, stridulation of the. + +Gratiolet, Prof., on the anthropomorphous apes; +on the evolution of the anthropomorphous apes; +on the difference in the development of the brains of apes and of man. + +Gray, Asa, on the gradation of species among the Compositae. + +Gray, J.E., on the caudal vertebrae of monkeys; +on the presence of rudiments of horns in the female of Cervulus moschatus; +on the horns of goats and sheep; +on crests of male antelopes; +on the beard of the ibex; +on the Berbura goat; +on sexual differences in the coloration of Rodents; +ornaments of male sloth; +on the colours of the Elands; +on the Sing-sing antelope; +on the colours of goats; +on Lemur Macaco; +on the hog-deer. + +"Greatest happiness principle." + +Greeks, ancient. + +Green, A.H., on beavers fighting; +on the voice of the beaver. + +Greenfinch, selected by a female canary. + +Greg, W.R., on the effects of natural selection on civilised nations; +on the early marriages of the poor; +on the Ancient Greeks. + +Grenadiers, Prussian. + +Greyhounds, numerical proportion of the sexes in; +numerical proportion of male and female births in. + +Grouse, red, monogamous; +pugnacity of young male; +producing a sound by beating their wings together; +duration of courtship of; +colours and nidification of. + +Gruber, Dr., on the occurrence of the supra-condyloid foramen in the +humerus of man; +on division of malar bone; +stridulation of locust; +on ephippiger. + +Grus americanus, age of mature plumage in; +breeding in immature plumage. + +Grus virgo, trachea of. + +Gryllus campestris, pugnacity of male. + +Gryllus domesticus. + +Grypus, sexual differences in the beak in. + +Guanacoes, battles of; +canine teeth of. + +Guanas, strife for women among the; +polyandry among the. + +Guanche skeletons, occurrence of the supra-condyloid foramen in the humerus +of. + +Guaranys, proportion of men and women among; +colour of new-born children of the; +beards of the. + +Guenee, A., on the sexes of Hyperythra. + +Guilding, L., on the stridulation of the Locustidae. + +Guillemot, variety of the. + +Guinea, sheep of, with males only horned. + +Guinea-fowl, monogamous; +occasional polygamy of the; +markings of the. + +Guinea-pigs, inheritance of the effects of operations by. + +Gulls, seasonal change of plumage in; +white. + +Gunther, Dr., on paddle of Ceradotus; +on hermaphroditism in Serranus; +on male fishes hatching ova in their mouths; +on mistaking infertile female fishes for males; +on the prehensile organs of male Plagiostomous fishes; +spines and brushes on fishes; +on the pugnacity of the male salmon and trout; +on the relative size of the sexes in fishes; +on sexual differences in fishes; +on the genus Callionymus; +on a protective resemblance of a pipe-fish; +on the genus Solenostoma; +on the coloration of frogs and toads; +combat of Testudo elegans; +on the sexual differences in the Ophidia; +on differences of the sexes of lizards. + +Gynanisa Isis, ocellated spots of. + +Gypsies, uniformity of, in various parts of the world. + +Habits, bad, facilitated by familiarity; +variability of the force of. + +Haeckel, E., on the origin of man; +on rudimentary characters; +on death caused by inflammation of the vermiform appendage; +on the canine teeth in man; +on the steps by which man became a biped; +on man as a member of the Catarrhine group; +on the position of the Lemuridae; +on the genealogy of the Mammalia; +on the lancelet; +on the transparency of pelagic animals; +on the musical powers of women. + +Hagen, H., and Walsh, B.D., on American Neuroptera. + +Hair, development of, in man; +character of, supposed to be determined by light and heat; +distribution of, in man; +possibly removed for ornamental purposes; +arrangement and direction of; +of the early progenitors of man; +different texture of, in distinct races; +and skin, correlation of colour of; +development of, in mammals; +management of, among different peoples; +great length of, in some North American tribes; +elongation of the, on the human head; +possible inherited effect of plucking out. + +Hairiness, difference of, in the sexes in man; +variation of, in races of men. + +Hairs and excretory pores, numerical relation of, in sheep. + +Hairy family, Siamese. + +Halbertsma, Prof., hermaphroditism in Serranus. + +Hamadryas baboon, turning over stones; +mane of the male. + +Hamilton, C., on the cruelty of the Kaffirs to animals; +on the engrossment of the women by the Kaffir chiefs. + +Hammering, difficulty of. + +Hancock, A., on the colours of the nudibranch Mollusca. + +Hands, larger at birth, in the children of labourers; +structure of, in the quadrumana; +and arms, freedom of, indirectly correlated with diminution of canines. + +Handwriting, inherited. + +Handyside, Dr., supernumerary mammae in men. + +Harcourt, E. Vernon, on Fringilla cannabina. + +Hare, protective colouring of the. + +Harelda glacialis. + +Hares, battles of male. + +Harlan, Dr., on the difference between field- and house-slaves. + +Harris, J.M., on the relation of complexion to climate. + +Harris, T.W., on the Katy-did locust; +on the stridulation of the grasshoppers; +on Oecanthus nivalis; +on the colouring of Lepidoptera; +on the colouring of Saturnia Io. + +Harting, spur of the Ornithorhynchus. + +Hartman, Dr., on the singing of Cicada septendecim. + +Hatred, persistence of. + +Haughton, S., on a variation of the flexor pollicis longus in man. + +Hawks, feeding orphan nestling. + +Hayes, Dr., on the diverging of sledge-dogs on thin ice. + +Haymond, R., on the drumming of the male Tetrao umbellus; +on the drumming of birds. + +Head, altered position of, to suit the erect attitude of man; +hairiness of, in man; +processes of, in male beetles; +artificial alterations of the form of the. + +Hearne, on strife for women among the North American Indians; +on the North American Indians' notion of female beauty; +repeated elopements of a North American woman. + +Heart, in the human embryo. + +Heat, supposed effects of. + +Hectocotyle. + +Hedge-warbler, young of the. + +Heel, small projection of, in the Aymara Indians. + +Hegt, M., on the development of the spurs in peacocks. + +Heliconidae, mimicry of, by other butterflies. + +Heliopathes, stridulation peculiar to the male. + +Heliothrix auriculata, young of. + +Helix pomatia, example of individual attachment in. + +Hellins, J., proportions of sexes of Lepidoptera reared by. + +Helmholtz, on pleasure derived from harmonies; +on the human eye; +on the vibration of the auditory hairs of crustacea; +the physiology of harmony. + +Hemiptera. + +Hemitragus, beardless in both sexes. + +Hemsbach, M. von, on medial mamma in man. + +Hen, clucking of. + +Hepburn, Mr., on the autumn song of the water-ouzel. + +Hepialus humuli, sexual difference of colour in the. + +Herbs, poisonous, avoided by animals. + +Hermaphroditism, of embryos; +in fishes. + +Herodias bubulcus, vernal moult of. + +Heron, Sir R., on the habits of peafowl. + +Herons, love-gestures of; +decomposed feathers in; +breeding plumage of; +young of the; +sometimes dimorphic; +continued growth of crest and plumes in the males of some; +change of colour in some. + +Hesperomys cognatus. + +Hetaerina, proportion of the sexes in; +difference in the sexes of. + +Heterocerus, stridulation of. + +Hewitt, Mr., on a game-cock killing a kite; +on the recognition of dogs and cats by ducks; +on the pairing of a wild duck with a pintail drake; +on the courtship of fowls; +on the coupling of pheasants with common hens. + +Hilgendorf, sounds produced by crustaceans. + +Hindoo, his horror of breaking his caste. + +Hindoos, local difference of stature among; +difference of, from Europeans; +colour of the beard in. + +Hipparchia Janira, instability of the ocellated spots of. + +Hippocampus, development of; +marsupial receptacles of the male. + +Hippocampus minor. + +Hippopotamus, nakedness of. + +Hips, proportions of, in soldiers and sailors. + +Hodgson, S., on the sense of duty. + +Hoffberg, on the horns of the reindeer; +on sexual preferences shewn by reindeer. + +Hoffman, Prof., protective colours; +fighting of frogs. + +Hog, wart-; +river-. + +Hog-deer. + +Holland, Sir H., on the effects of new diseases. + +Homologous structures, correlated variation of. + +Homoptera, stridulation of the, and Orthoptera, discussed. + +Honduras, Quiscalus major in. + +Honey-buzzard of India, variation in the crest of. + +Honey-sucker, females and young of. + +Honey-suckers, moulting of the; +Australian, nidification of. + +Honour, law of. + +Hooker, Dr., forbearance of elephant to his keeper; +on the colour of the beard in man. + +Hookham, Mr., on mental concepts in animals. + +Hoolock Gibbon, nose of. + +Hoopoe, sounds produced by male. + +Hoplopterus armatus, wing-spurs of. + +Hornbill, African, inflation of the neck-wattle of the male during +courtship. + +Hornbills, sexual difference in the colour of the eyes in; +nidification and incubation of. + +Horne, C., on the rejection of a brightly-coloured locust by lizards and +birds. + +Horns, sexual differences of, in sheep and goats; +loss of, in female merino sheep; +development of, in deer; +development in antelopes; +from the head and thorax, in male beetles; +of deer; +originally a masculine character in sheep; +and canine teeth, inverse development of. + +Horse, fossil, extinction of the, in South America; +polygamous; +canine teeth of male; +winter change of colour. + +Horses, rapid increase of, in South America; +diminution of canine teeth in; +dreaming; +of the Falkland Islands and Pampas; +numerical proportion of the sexes, in; +lighter in winter in Siberia; +sexual preferences in; +pairing preferently with those of the same colour; +numerical proportion of male and female births in; +formerly striped. + +Hottentot women, peculiarities of. + +Hottentots, lice of; +readily become musicians; +notions of female beauty of the; +compression of nose by. + +Hough, Dr. S., men's temperature more variable than women's; +proportion of sexes in man. + +House-slaves, difference of, from field-slaves. + +Houzeau, on the baying of the dog; +on reason in dogs; +birds killed by telegraph wires; +on the cries of domestic fowls and parrots; +animals feel no pity; +suicide in the Aleutian Islands. + +Howorth, H.H., extinction of savages. + +Huber, P., on ants playing together; +on memory in ants; +on the intercommunication of ants; +on the recognition of each other by ants after separation. + +Huc, on Chinese opinions of the appearance of Europeans. + +Huia, the, of New Zealand. + +Human, man, classed alone in a kingdom. + +Human sacrifices. + +Humanity, unknown among some savages; +deficiency of, among savages. + +Humboldt, A. von, on the rationality of mules; +on a parrot preserving the language of a lost tribe; +on the cosmetic arts of savages; +on the exaggeration of natural characters by man; +on the red painting of American Indians. + +Hume, D., on sympathetic feelings. + +Humming-bird, racket-shaped feathers in the tail of a; +display of plumage by the male. + +Humming-birds, ornament their nests; +polygamous; +proportion of the sexes in; +sexual differences in; +pugnacity of male; +modified primaries of male; +coloration of the sexes of; +display by; +nidification of the; +colours of female; +young of. + +Humour, sense of, in dogs. + +Humphreys, H.N., on the habits of the stickleback. + +Hunger, instinct of. + +Huns, ancient, flattening of the nose by the. + +Hunter, J., on the number of species of man; +on secondary sexual characters; +on the general behaviour of female animals during courtship; +on the muscles of the larynx in song-birds; +on strength of males; +on the curled frontal hair of the bull; +on the rejection of an ass by a female zebra. + +Hunter, W.W., on the recent rapid increase of the Santali; +on the Santali. + +Huss, Dr. Max, on mammary glands. + +Hussey, Mr., on a partridge distinguishing persons. + +Hutchinson, Col., example of reasoning in a retriever. + +Hutton, Captain, on the male wild goat falling on his horns. + +Huxley, T.H., on the structural agreement of man with the apes; +on the agreement of the brain in man with that of lower animals; +on the adult age of the orang; +on the embryonic development of man; +on the origin of man; +on variation in the skulls of the natives of Australia; +on the abductor of the fifth metatarsal in apes; +on the nature of the reasoning power; +on the position of man; +on the suborders of primates; +on the Lemuridae; +on the Dinosauria; +on the amphibian affinities of the Ichthyosaurians; +on variability of the skull in certain races of man; +on the races of man; +Supplement on the brain. + +Hybrid birds, production of. + +Hydrophobia, communicable between man and the lower animals. + +Hydroporus, dimorphism of females of. + +Hyelaphus porcinus. + +Hygrogonus. + +Hyla, singing species of. + +Hylobates, absence of the thumb in; +upright progression of some species of; +maternal affection in a; +direction of the hair on the arms of species of; +females of, less hairy below than males. + +Hylobates agilis, hair on the arms of; +musical voice of the; +superciliary ridge of; +voice of. + +Hylobates hoolock, sexual difference of colour in. + +Hylobates lar, hair on the arms of; +female less hairy. + +Hylobates leuciscus, song of. + +Hylobates syndactylus, laryngeal sac of. + +Hylophila prasinana. + +Hymonoptera, large size of the cerebral ganglia in; +classification of; +sexual differences in the wings of; +aculeate, relative size of the sexes of. + +Hymenopteron, parasitic, with a sedentary male. + +Hyomoschus aquaticus. + +Hyperythra, proportion of the sexes in. + +Hypogymna dispar, sexual difference of colour in. + +Hypopyra, coloration of. + +Ibex, male, falling on his horns; +beard of the. + +Ibis, white, change of colour of naked skin in, during the breeding season; +scarlet, young of the. + +Ibis tantalus, age of mature plumage in; +breeding in immature plumage. + +Ibises, decomposed feathers in; +white; +and black. + +Ichneumonidae, difference of the sexes in. + +Ichthyopterygia. + +Ichthyosaurians. + +Idiots, microcephalous, their characters and habits; +hairiness and animal nature of their actions; +microcephalous, imitative faculties of. + +Iguana tuberculata. + +Iguanas. + +illegitimate and legitimate children, proportion of the sexes in. + +Imagination, existence of, in animals. + +Imitation, of man by monkeys; +tendency to, in monkeys,; +microcephalous idiots and savages; +influence of. + +Immature plumage of birds. + +Implacentata. + +Implements, employed by monkeys; +fashioning of, peculiar to man. + +Impregnation, period of, influence of, upon sex. + +Improvement, progressive, man alone supposed to be capable of. + +Incisor teeth, knocked out or filed by some savages. + +Increase, rate of; +necessity of checks in. + +Indecency, hatred of, a modern virtue. + +India, difficulty of distinguishing the native races of; +Cyprinidae of; +colour of the beard in races of men of. + +Indian, North American, honoured for scalping a man of another tribe. + +Individuality, in animals. + +Indolence of man, when free from a struggle for existence. + +Indopicus carlotta, colours of the sexes of. + +Infanticide, prevalence of; +supposed cause of; +prevalence and causes of. + +Inferiority, supposed physical, of man. + +Inflammation of the bowels, occurrence of, in Cebus Azarae. + +Inheritance, of long and short sight; +of effects of use of vocal and mental organs; +of moral tendencies; +laws of; +sexual; +sexually limited. + +Inquisition, influence of the. + +Insanity, hereditary. + +insect, fossil, from the Devonian. + +Insectivora, absence of secondary sexual characters in. + +Insects, relative size of the cerebral ganglia in; +male, appearance of, before the females; +pursuit of female, by the males; +period of development of sexual characters in; +secondary sexual characters of; +kept in cages; +stridulation. + +Insessores, vocal organs of. + +Instep, depth of, in soldiers and sailors. + +Instinct and intelligence. + +Instinct, migratory, vanquishing the maternal. + +Instinctive actions, the result of inheritance. + +Instinctive impulses, difference of the force; +and moral impulses, alliance of. + +Instincts, complex origin of, through natural selection; +possible origin of some; +acquired, of domestic animals; +variability of the force of; +difference of force between the social and other; +utilised for new purposes. + +Instrumental music of birds. + +Intellect, influence of, in natural selection in civilised society. + +Intellectual faculties, their influence on natural selection in man; +probably perfected through natural selection. + +Intelligence, Mr. H. Spencer on the dawn of. + +Intemperance, no reproach among savages; +its destructiveness. + +Intoxication in monkeys. + +Iphias glaucippe. + +Iris, sexual difference in the colour of the, in birds. + +Ischio-pubic muscle. + +Ithaginis cruentus, number of spurs in. + +Iulus, tarsal suckers of the males of. + +Jackals learning from dogs to bark. + +Jack-snipe, coloration of the. + +Jacquinot, on the number of species of man. + +Jaeger, Dr., length of bones increased from carrying weights; +on the difficulty of approaching herds of wild animals; +male Silver-pheasant, rejected when his plumage was spoilt. + +Jaguars, black. + +Janson, E.W., on the proportions of the sexes in Tomicus villosus; +on stridulant beetles. + +Japan, encouragement of licentiousness in. + +Japanese, general beardlessness of the; +aversion of the, to whiskers. + +Jardine, Sir W., on the Argus pheasant. + +Jarrold, Dr., on modifications of the skull induced by unnatural position. + +Jarves, Mr., on infanticide in the Sandwich Islands. + +Javans, relative height of the sexes of; +notions of female beauty. + +Jaw, influence of the muscles of the, upon the physiognomy of the apes. + +Jaws, smaller proportionately to the extremities; +influence of food upon the size of; +diminution of, in man; +in man, reduced by correlation. + +Jay, young of the; +Canada, young of the. + +Jays, new mates found by; +distinguishing persons. + +Jeffreys, J. Gwyn, on the form of the shell in the sexes of the +Gasteropoda; +on the influence of light upon the colours of shells. + +Jelly-fish, bright colours of some. + +Jenner, Dr., on the voice of the rook; +on the finding of new mates by magpies; +on retardation of the generative functions in birds. + +Jenyns, L., on the desertion of their young by swallows; +on male birds singing after the proper season. + +Jerdon, Dr., on birds dreaming; +on the pugnacity of the male bulbul; +on the pugnacity of the male Ortygornis gularis; +on the spurs of Galloperdix; +on the habits of Lobivanellus; +on the spoonbill; +on the drumming of the Kalij-pheasant; +on Indian bustards; +on Otis bengalensis; +on the ear-tufts of Sypheotides auritus; +on the double moults of certain birds; +on the moulting of the honeysuckers; +on the moulting of bustards, plovers, and drongos; +on the spring change of colour in some finches; +on display in male birds; +on the display of the under-tail coverts by the male bulbul; +on the Indian honey-buzzard; +on sexual differences in the colour of the eyes of hornbills; +on the markings of the Tragopan pheasant; +on the nidification of the Orioles; +on the nidification of the hornbills; +on the Sultan yellow-tit; +on Palaeornis javanicus; +on the immature plumage of birds; +on representative species of birds; +on the habits of Turnix; +on the continued increase of beauty of the peacock; +on coloration in the genus Palaeornis. + +Jevons, W.S., on the migrations of man. + +Jews, ancient use of flint tools by the; +uniformity of, in various parts of the world; +numerical proportion of male and female births among the; +ancient, tattooing practised by. + +Johnstone, Lieut., on the Indian elephant. + +Jollofs, fine appearance of the. + +Jones, Albert, proportion of sexes of Lepidoptera, reared by. + +Juan Fernandez, humming-birds of. + +Junonia, sexual differences of colouring in species of. + +Jupiter, comparison with Assyrian effigies. + +Kaffir skull, occurrence of the diastema in a. + +Kaffirs, their cruelty to animals; +lice of the; +colour of the; +engrossment of the handsomest women by the chiefs of the; +marriage-customs of the. + +Kalij-pheasant, drumming of the male; +young of. + +Kallima, resemblance of, to a withered leaf. + +Kulmucks, general beardlessness of; +aversion of, to hairs on the face; +marriage-customs of the. + +Kangaroo, great red, sexual difference in the colour of. + +Kant, Imm., on duty; +on self-restraint; +on the number of species of man. + +Katy-did, stridulation of the. + +Keen, Dr., on the mental powers of snakes. + +Keller, Dr., on the difficulty of fashioning stone implements. + +Kent, W.S., elongation of dorsal fin of Callionymus lyra; +courtship of Labrus mixtus; +colours and courtship of Cantharus lineatus. + +Kestrels, new mates found by. + +Kidney, one, doing double work in disease. + +King, W.R., on the vocal organs of Tetrao cupido; +on the drumming of grouse; +on the reindeer; +on the attraction of male deer by the voice of the female. + +King and Fitzroy, on the marriage-customs of the Fuegians. + +King-crows, nidification of. + +Kingfisher, racket-shaped feathers in the tail of a. + +Kingfishers, colours and nidification of the; +immature plumage of the; +young of the. + +King Lory, immature plumage of the. + +Kingsley, C., on the sounds produced by the Umbrina. + +Kirby and Spence, on sexual differences in the length of the snout in +Curculionidae; +on the courtship of insects; +on the elytra of Dytiscus; +on peculiarities in the legs of male insects; +on the relative size of the sexes in insects; +on the Fulgoridae; +on the habits of the Termites; +on difference of colour in the sexes of beetles; +on the horns of the male lamellicorn beetles; +on hornlike processes in male Curculionidae; +on the pugnacity of the male stag-beetle. + +Kite, killed by a game-cock. + +Knot, retention of winter plumage by the. + +Knox, R., on the semilunar fold; +on the occurrence of the supra-condyloid foramen in the humerus of man; +on the features of the young Memmon. + +Koala, length of the caecum in. + +Kobus ellipsiprymnus, proportion of the sexes in. + +Kolreuter, on the sterility of hybrid plants. + +Koodoo, development of the horns of the; +markings of the. + +Koppen, F.T., on the migratory locust. + +Koraks, marriage customs of. + +Kordofan, protuberances artificially produced by natives of. + +Korte, on the proportion of sexes in locusts; +Russian locusts. + +Kovalevsky, A., on the affinity of the Ascidia to the Vertebrata. + +Kovalevsky, W., on the pugnacity of the male capercailzie; +on the pairing of the capercailzie. + +Krause, on a convoluted body at the extremity of the tail in a Macacus and +a cat. + +Kupffer, Prof., on the affinity of the Ascidia to the Vertebrata. + +Labidocera Darwinii, prehensile organs of the male. + +Labrus, splendid colours of the species of. + +Labrus mixtus, sexual differences in. + +Labrus pavo. + +Lacertilia, sexual differences of. + +Lafresnaye, M. de, on birds of paradise. + +Lamarck, on the origin of man. + +Lamellibranchiata. + +Lamellicorn beetles, horn-like processes from the head and thorax of; +influence of sexual selection on. + +Lamellicornia, stridulation of. + +Lamont, Mr., on the tusks of the walrus; +on the use of its tusks by the walrus; +on the bladder-nose seal. + +Lampornis porphyrurus, colours of the female. + +Lampyridae, distasteful to mammals. + +Lancelet. + +Landois, H., gnats attracted by sound; +on the production of sound by the Cicadae; +on the stridulating organ of the crickets; +on Decticus; +on the stridulating organs of the Acridiidae; +stridulating apparatus, in Orthoptera; +on the stridulation of Necrophorus; +on the stridulant organ of Cerambyx heros; +on the stridulant organ of Geotrupes; +on the stridulating organs in the Cleoptera; +on the ticking of Anobium. + +Landor, Dr., on remorse for not obeying tribal custom. + +Language, an art; +articulate, origin of; +relation of the progress of, to the development of the brain; +effects of inheritance in production of; +complex structure of, among barbarous nations; +natural selection in; +gesture; +primeval; +of a lost tribe preserved by a parrot. + +Languages, presence of rudiments in; +classification of; +variability of; +crossing or blending of; +complexity of, no test of perfection or proof of special creation; +resemblance of, evidence of community of origin. + +Languages and species, identity of evidence of their gradual development. + +Lanius, characters of young. + +Lanius rufus, anomalous young of. + +Lankester, E.R., on comparative longevity; +on the destructive effects of intemperance. + +Lanugo of the human foetus. + +Lapponian language, highly artificial. + +Lark, proportion of the sexes in the; +female, singing of the. + +Larks, attracted by a mirror. + +Lartet, E., comparison of cranial capacities of skulls of recent and +tertiary mammals; +on the size of the brain in mammals; +on Dryopithecus; +on pre-historic flutes. + +Larus, seasonal change of plumage in. + +Larva, luminous, of a Brazilian beetle. + +Larynx, muscles of the, in songbirds. + +Lasiocampa quercus, attraction of males by the female; +sexual difference of colour in. + +Latham, R.G., on the migrations of man. + +Latooka, perforation of the lower lip by the women of. + +Laurillard, on the abnormal division of the malar bone in man. + +Lawrence, W., on the superiority of savages to Europeans in power of sight; +on the colour of negro infants; +on the fondness of savages for ornaments; +on beardless races; +on the beauty of the English aristocracy. + +Layard, E.L., on the instance of rationality in a cobra; +on the pugnacity of Gallus Stanleyi. + +Laycock, Dr., on vital periodicity; +theroid nature of idiots. + +Leaves, autumn, tints useless. + +Lecky, Mr., on the sense of duty; +on suicide; +on the practice of celibacy; +his view of the crimes of savages; +on the gradual rise of morality. + +Leconte, J.L., on the stridulant organ in the Coprini and Dynastini. + +Lee, H., on the numerical proportion of the sexes in the trout. + +Leg, calf of the, artificially modified. + +Legitimate and illegitimate children, proportion of the sexes in. + +Legs, variation of the length of the, in man; +proportions of, in soldiers and sailors; +front, atrophied in some male butterflies; +peculiarities of, in male insects. + +Leguay, on the occurrence of the supra-condyloid foramen in the humerus of +man. + +Lek of the black-cock and capercailzie. + +Lemoine, Albert, on the origin of language. + +Lemur macaco, sexual difference of colour in. + +Lemuridae, ears of the; +variability of the muscles in the; +position and derivation of the; +their origin. + +Lemurs, uterus in the. + +Lenguas, disfigurement of the ears of the. + +Leopards, black. + +Lepidoptera, numerical proportions of the sexes in the; +colouring of; +ocellated spots of. + +Lepidosiren. + +Leptalides, mimicry of. + +Leptorhynchus angustatus, pugnacity of male. + +Leptura testacea, difference of colour in the sexes. + +Leroy, on the wariness of young foxes in hunting-districts; +on the desertion of their young by swallows. + +Leslie, D., marriage customs of Kaffirs. + +Lesse, valley of the. + +Lesson, on the birds of paradise; +on the sea-elephant. + +Lessona, M., observations on Serranus. + +Lethrus cephalotes, pugnacity of the males of. + +Leuciscus phoxinus. + +Leuckart, R., on the vesicula prostatica; +on the influence of the age of parents on the sex of offspring. + +Levator claviculae muscle. + +Libellula depressa, colour of the male. + +Libellulidae, relative size of the sexes of; +difference in the sexes of. + +Lice of domestic animals and man. + +Licentiousness a check upon population; +prevalence of, among savages. + +Lichtenstein, on Chera progne. + +Life, inheritance at corresponding periods of. + +Light, effects on complexion; +influence of, upon the colours of shells. + +Lilford, Lord, the ruff attracted by bright objects. + +Limosa lapponica. + +Linaria. + +Linaria montana. + +Lindsay, Dr. W.L., diseases communicated from animals to man; +madness in animals; +the dog considers his master his God. + +Linnaeus, views of, as to the position of man. + +Linnet, numerical proportion of the sexes in the; +crimson forehead and breast of the; +courtship of the. + +Lion, polygamous; +mane of the, defensive; +roaring of the. + +Lions, stripes of young. + +Lips, piercing of the, by savages. + +Lithobius, prehensile appendages of the female. + +Lithosia, coloration in. + +Littorina littorea. + +Livingstone, Dr., manner of sitting of gorilla; +on the influence of dampness and dryness on the colour of the skin; +on the liability of negroes to tropical fevers after residence in a cold +climate; +on the spur-winged goose; +on weaverbirds; +on an African night-jar; +on the battle-scars of South African male mammals; +on the removal of the upper incisors by the Batokas; +on the perforation of the upper lip by the Makalolo; +on the Banyai. + +Livonia, numerical proportion of male and female births in. + +Lizards, relative size of the sexes of; +gular pouches of. + +Lloyd, L., on the polygamy of the capercailzie and bustard; +on the numerical proportion of the sexes in the capercailzie and blackcock; +on the salmon; +on the colours of the sea-scorpion; +on the pugnacity of male grouse; +on the capercailzie and blackcock; +on the call of the capercailzie; +on assemblages of grouse and snipes; +on the pairing of a shield-drake with a common duck; +on the battles of seals; +on the elk. + +Lobivanellus, wing-spurs in. + +Local influences, effect of, upon stature. + +Lockwood, Mr., on the development of Hippocampus. + +Lockwood, Rev. S., musical mouse. + +Locust, bright-coloured, rejected by lizards and birds. + +Locust, migratory; +selection by female. + +Locustidae, stridulation of the; +descent of the. + +Locusts, proportion of sexes in; +stridulation of. + +Longicorn beetles, difference of the sexes of, in colour; +stridulation of. + +Lonsdale, Mr., on an example of personal attachment in Helix pomatia. + +Lophobranchii, marsupial receptacles of the male. + +Lophophorus, habits of. + +Lophorina atra, sexual difference in coloration of. + +Lophornis ornatus. + +Lord, J.K., on Salmo lycaodon. + +Lory, King; +immature plumage of the. + +Lory, king, constancy of. + +Love-antics and dances of birds. + +Lowne, B.T., on Musca vomitoria. + +Loxia, characters of young of. + +Lubbock, Sir J., on the antiquity of man; +on the origin of man; +on the mental capacity of savages; +on the origin of implements; +on the simplification of languages; +on the absence of the idea of God among certain races of men; +on the origin of the belief in spiritual agencies; +on superstitions; +on the sense of duty; +on the practice of burying the old and sick among the Fijians; +on the immorality of savages; +on Mr. Wallace's claim to the origination of the idea of natural selection; +on the former barbarism of civilised nations; +on improvements in the arts among savages; +on resemblances of the mental characters in different races of men; +on the arts practised by savages; +on the power of counting in primeval man; +on the prehensile organs of the male Labidocera Darwinii; +on Chloeon; +on Smynthurus luteus; +finding of new mates by jays; +on strife for women among the North American Indians; +on music; +on the ornamental practices of savages; +on the estimation of the beard among the Anglo-Saxons; +on artificial deformation of the skull; +on "communal marriages;" +on exogamy; +on the Veddahs; +on polyandry. + +Lucanidae, variability of the mandibles in the male. + +Lucanus, large size of males of. + +Lucanus cervus, numerical proportion of sexes of; +weapons of the male. + +Lucanus elaphus, use of mandibles of; +large jaws of male. + +Lucas, Prosper, on pigeons; +on sexual preference in horses and bulls. + +Luminosity in insects. + +Lunar periods. + +Lund, Dr., on skulls found in Brazilian caves. + +Lungs, enlargement of, in the Quichua and Aymara Indians; +a modified swim-bladder; +different capacity of, in races of man. + +Luschka, Prof., on the termination of the coccyx. + +Luxury, expectation of life uninfluenced by. + +Lycaena, sexual differences of colour in species of. + +Lycaenae, colours of. + +Lyell, Sir C., on the antiquity of man; +on the origin of man; +on the parallelism of the development of species and languages; +on the extinction of languages; +on the Inquisition; +on the fossil remains of vertebrata; +on the fertility of mulattoes. + +Lynx, Canadian throat-ruff of the. + +Lyre-bird, assemblies of. + +Macacus, ears of; +convoluted body in the extremity of the tail of; +variability of the tail in species of; +whiskers of species of. + +Macacus brunneus. + +Macacus cynomolgus, superciliary ridge of; +beard and whiskers of; +becoming white with age. + +Macacus ecaudatus. + +Macacus lasiotus, facial spots of. + +Macacus nemestrinus. + +Macacus radiatus. + +Macacus rhesus, sexual difference in the colour of. + +Macalister, Prof., on variations of the palmaris accessorius muscle; +on muscular abnormalities in man; +on the greater variability of the muscles in men than in women. + +Macaws, Mr. Buxton's observations on. + +McCann, J., on mental individuality. + +McClelland, J., on the Indian Cyprinidae. + +Macculloch, Col., on an Indian village without any female children. + +Macculloch, Dr., on tertian ague in a dog. + +Macgillivray, W., on the vocal organs of birds; +on the Egyptian goose; +on the habits of woodpeckers; +on the habits of the snipe; +on the whitethroat; +on the moulting of the snipes; +on the moulting of the Anatidae; +on the finding of new mates by magpies; +on the pairing of a blackbird and thrush; +on pied ravens; +on the guillemots; +on the colours of the tits; +on the immature plumage of birds. + +Machetes, sexes and young of. + +Machetes pugnax, supposed to be polygamous; +numerical proportion of the sexes in; +pugnacity of the male; +double moult in. + +McIntosh, Dr., colours of the Nemertians. + +McKennan, marriage customs of Koraks. + +Mackintosh, on the moral sense. + +MacLachlan, R., on Apatania muliebris and Boreus hyemalis; +on the anal appendages of male insects; +on the pairing of dragon-flies; +on dragon-flies; +on dimorphism in Agrion; +on the want of pugnacity in male dragon-flies; +colour of ghost-moth in the Shetland Islands. + +M'Lennan, Mr., on infanticide; +on the origin of the belief in spiritual agencies; +on the prevalence of licentiousness among savages; +on the primitive barbarism of civilised nations; +on traces of the custom of the forcible capture of wives; +on polyandry. + +Macnamara, Mr., susceptibility of Andaman islanders and Nepalese to change. + +M'Neill, Mr., on the use of the antlers of deer; +on the Scotch deerhound; +on the long hairs on the throat of the stag; +on the bellowing of stags. + +Macropus, courtship of. + +Macrorhinus proboscideus, structure of the nose of. + +Magpie, power of speech of; +vocal organs of the; +nuptial assemblies of; +new mates found by; +stealing bright objects; +young of the; +coloration of the. + +Maillard, M., on the proportion of the sexes in a species of Papilio from +Bourbon. + +Maine, Sir Henry, on the absorption of one tribe by another; +a desire for improvement not general. + +Major, Dr. C. Forsyth, on fossil Italian apes; +skull of Bos etruscus; +tusks of miocene pigs. + +Makalolo, perforation of the upper lip by the. + +Malar bone, abnormal division of, in man. + +Malay, Archipelago, marriage-customs of the savages of the. + +Malays, line of separation between the Papuans and the; +general beardlessness of the; +staining of the teeth among; +aversion of some, to hairs on the face. + +Malays and Papuans, contrasted characters of. + +Male animals, struggles of, for the possession of the females; +eagerness of, in courtship; +generally more modified than female; +differ in the same way from females and young. + +Male characters, developed in females; +transfer of, to female birds. + +Male, sedentary, of a hymenopterous parasite. + +Malefactors. + +Males, presence of rudimentary female organs in. + +Males and females, comparative numbers of; +comparative mortality of, while young. + +Malherbe, on the woodpeckers. + +Mallotus Peronii. + +Mallotus villosus. + +Malthus, T., on the rate of increase of population. + +Maluridae, nidification of the. + +Malurus, young of. + +Mammae, rudimentary, in male mammals; +supernumerary, in women; +of male human subject. + +Mammalia, Prof. Owen's classification of; +genealogy of the. + +Mammals, recent and tertiary, comparison of cranial capacity of; +nipples of; +pursuit of female, by the males; +secondary sexual characters of; +weapons of; +relative size of the sexes of; +parallelism of, with birds in secondary sexual characters; +voices of, used especially during the breeding season. + +Man, variability of; +erroneously regarded as more domesticated than other animals; +migrations of; +wide distribution of; +causes of the nakedness of; +supposed physical inferiority of; +a member of the Catarrhine group; +early progenitors of; +transition from ape indefinite; +numerical proportions of the sexes in; +difference between the sexes; +proportion of sexes amongst the illegitimate; +different complexion of male and female negroes; +secondary sexual characters of; +primeval condition of. + +Mandans, correlation of colour and texture of hair in the. + +Mandible, left, enlarged in the male of Taphroderes distortus. + +Mandibles, use of the, in Ammophila; +large, of Corydalis cornutus; +large, of male Lucanus elaphus. + +Mandrill, number of caudal vertebrae in the; +colours of the male. + +Mantegazza, Prof., on last molar teeth of man; +bright colours in male animals; +on the ornaments of savages; +on the beardlessness of the New Zealanders; +on the exaggeration of natural characters by man. + +Mantell, W., on the engrossment of pretty girls by the New Zealand chiefs. + +Mantis, pugnacity of species of. + +Maories, mortality of; +infanticide and proportion of sexes; +distaste for hairiness amongst men. + +Marcus Aurelius, on the origin of the moral sense; +on the influence of habitual thoughts. + +Mareca penelope. + +Marks, retained throughout groups of birds. + +Marriage, restraints upon, among savages; +influence of, upon morals; +influence of, on mortality; +development of. + +Marriages, early; +communal. + +Marshall, Dr. W., protuberances on birds' heads; +on the moulting of birds; +advantage to older birds of paradise. + +Marshall, Col., interbreeding amongst Todas; +infanticide and proportion of sexes with Todas; +choice of husband amongst Todas. + +Marshall, Mr., on the brain of a Bushwoman. + +Marsupials, development of the nictitating membrane in; +uterus of; +possession of nipples by; +their origin from Monotremata; +abdominal sacs of; +relative size of the sexes of; +colours of. + +Marsupium, rudimentary in male marsupials. + +Martin, W.C.L., on alarm manifested by an orang at the sight of a turtle; +on the hair in Hylobates; +on a female American deer; +on the voice of Hylobates agilis; +on Semnopithecus nemaeus. + +Martin, on the beards of the inhabitants of St. Kilda. + +Martins deserting their young. + +Martins, C., on death caused by inflammation of the vermiform appendage. + +Mastoid processes in man and apes. + +Maudsley, Dr., on the influence of the sense of smell in man; +on idiots smelling their food; +on Laura Bridgman; +on the development of the vocal organs; +moral sense failing in incipient madness; +change of mental faculties at puberty in man. + +Mayers, W.F., on the domestication of the goldfish in China. + +Mayhew, E., on the affection between individuals of different sexes in the +dog. + +Maynard, C.J., on the sexes of Chrysemys picta. + +Meckel, on correlated variation of the muscles of the arm and leg. + +Medicines, effect produced by, the same in man and in monkeys. + +Medusae, bright colours of some. + +Megalithic structures, prevalence of. + +Megapicus validus, sexual difference of colour in. + +Megasoma, large size of males of. + +Meigs, Dr. A., on variation in the skulls of the natives of America. + +Meinecke, on the numerical proportion of the sexes in butterflies. + +Melanesians, decrease of. + +Meldola, Mr., colours and marriage flight of Colias and Pieris. + +Meliphagidae, Australian, nidification of. + +Melita, secondary sexual characters of. + +Meloe, difference of colour in the sexes of a species of. + +Memnon, young. + +Memory, manifestations of, in animals. + +Mental characters, difference of, in different races of men. + +Mental faculties, diversity of, in the same race of men; +inheritance of; +variation of, in the same species; +similarity of the, in different races of man; +of birds. + +Mental powers, difference of, in the two sexes in man. + +Menura Alberti, song of. + +Menura superba, long tails of both sexes of. + +Merganser, trachea of the male. + +Merganser serrator, male plumage of. + +Mergus cucullatus, speculum of. + +Mergus merganser, young of. + +Metallura, splendid tail-feathers of. + +Methoca ichneumonides, large male of. + +Meves, M., on the drumming of the snipe. + +Mexicans, civilisation of the, not foreign. + +Meyer, on a convoluted body at the extremity of the tail in a Macacus and a +cat. + +Meyer, Dr. A., on the copulation of Phryganidae of distinct species. + +Meyer, Prof. L., on development of helix of ear; +men's ears more variable than women's; +antennae serving as ears. + +Migrations of man, effects of. + +Migratory instinct of birds; +vanquishing the maternal. + +Mill, J.S., on the origin of the moral sense; +on the "greatest happiness principle;" +on the difference of the mental powers in the sexes of man. + +Millipedes. + +Milne-Edwards, H., on the use of enlarged chelae of the male Gelasimus. + +Milvago leucurus, sexes and young of. + +Mimicry. + +Mimus polyglottus. + +Mind, difference of, in man and the highest animals; +similarity of the, in different races. + +Minnow, proportion of the sexes in the. + +Mirror, behaviour of monkeys before. + +Mirrors, larks attracted by. + +Mitchell, Dr., interbreeding in the Hebrides. + +Mitford, selection of children in Sparta. + +Mivart, St. George, on the reduction of organs; +on the ears of the lemuroidea; +on variability of the muscles in lemuroidea; +on the caudal vertebrae of monkeys; +on the classification of the primates; +on the orang and on man; +on differences in the lemuroidea; +on the crest of the male newt. + +Mobius, Prof., on reasoning powers in a pike. + +Mocking-thrush, partial migration of; +young of the. + +Modifications, unserviceable. + +Moggridge, J.T., on habits of spiders; +on habits of ants. + +Moles, numerical proportion of the sexes in; +battles of male. + +Mollienesia petenensis, sexual difference in. + +Mollusca, beautiful colours and shapes of; +absence of secondary sexual characters in the. + +Molluscoida. + +Monacanthus scopas and M. Peronii. + +Monboddo, Lord, on music. + +Mongolians, perfection of the senses in. + +Monkey, protecting his keeper from a baboon; +bonnet-; +rhesus-, sexual difference in colour of the; +moustache-, colours of the. + +Monkeys, liability of, to the same diseases as man; +male, recognition of women by; +diversity of the mental faculties in; +breaking hard fruits with stones; +hands of the; +basal caudal vertebrae of, imbedded in the body; +revenge taken by; +maternal affection in; +variability of the faculty of attention in; +American, manifestation of reason in; +using stones and sticks; +imitative faculties of; +signal-cries of; +mutual kindnesses of; +sentinels posted by; +human characters of; +American, direction of the hair on the arms of some; +gradation of species of; +beards of; +ornamental characters of; +analogy of sexual differences of, with those of man; +different degrees of difference in the sexes of; +expression of emotions by; +generally monogamous habits of; +polygamous habits of some; +naked surfaces of; +courtship of. + +Monogamy, not primitive. + +Monogenists. + +Mononychus pseudacori, stridulation of. + +Monotremata, development of the nictitating membrane in; +lactiferous glands of; +connecting mammals with reptiles. + +Monstrosities, analogous, in man and lower animals; +caused by arrest of development; +correlation of; +transmission of. + +Montagu, G., on the habits of the black and red grouse; +on the pugnacity of the ruff; +on the singing of birds; +on the double moult of the male pintail. + +Monteiro, Mr., on Bucorax abyssinicus. + +Montes de Oca, M., on the pugnacity of male Humming-birds. + +Monticola cyanea. + +Monuments, as traces of extinct tribes. + +Moose, battles of; +horns of the, an incumbrance. + +Moral and instinctive impulses, alliance of. + +Moral faculties, their influence on natural selection in man. + +Moral rules, distinction between the higher and lower. + +Moral sense, so-called, derived from the social instincts; +origin of the. + +Moral tendencies, inheritance of. + +Morality, supposed to be founded in selfishness; +test of, the general welfare of the community; +gradual rise of; +influence of a high standard of. + +Morgan, L.H., on the beaver; +on the reasoning powers of the beaver; +on the forcible capture of wives; +on the castoreum of the beaver; +marriage unknown in primeval times; +on polyandry. + +Morley, J., on the appreciation of praise and fear of blame. + +Morris, F.O., on hawks feeding an orphan nestling. + +Morse, Dr., colours of mollusca. + +Morselli, E., division of the malar bone. + +Mortality, comparative, of female and male. + +Morton on the number of species of man. + +Moschkau, Dr. A., on a speaking starling. + +Moschus moschiferus, odoriferous organs of. + +Motacillae, Indian, young of. + +Moth, odoriferous. + +Moths, absence of mouth in some males; +apterous female; +male, prehensile use of the tarsi by; +male, attracted by females; +sound produced by; +coloration of; +sexual differences of colour in. + +Motmot, inheritance of mutilation of tail feathers; +racket-shaped feathers in the tail of a. + +Moult, double; +double annual, in birds. + +Moulting of birds. + +Moults, partial. + +Mouse, song of. + +Moustache-monkey, colours of the. + +Moustaches, in monkeys. + +Mud-turtle, long claws of the male. + +Mulattoes, persistent fertility of; +immunity of, from yellow fever. + +Mule, sterility and strong vitality of the. + +Mules, rational. + +Muller, Ferd., on the Mexicans and Peruvians. + +Muller, Fritz, on astomatous males of Tanais; +on the disappearance of spots and stripes in adult mammals; +on the proportions of the sexes in some Crustacea; +on secondary sexual characters in various Crustaceans; +musical contest between male Cicadae; +mode of holding wings in Castina; +on birds shewing a preference for certain colours; +on the sexual maturity of young amphipod Crustacea. + +Muller, Hermann, emergence of bees, from pupa; +pollen-gathering of bees; +proportion of sexes in bees; +courting of Eristalis; +colour and sexual selection with bees. + +Muller, J., on the nictitating membrane and semilunar fold. + +Muller, Max, on the origin of language; +language implies power of general conception; +struggle for life among the words, etc., of languages. + +Muller, S., on the banteng; +on the colours of Semnopithecus chrysomelas. + +Muntjac-deer, weapons of the. + +Murie, J., on the reduction of organs; +on the ears of the Lemuroidea; +on variability of the muscles in the Lemuroidea; +basal caudal vertebrae of Macacus brunneus imbedded in the body; +on the manner of sitting in short-tailed apes; +on differences in the Lemuroidea; +on the throat-pouch of the male bustard; +on the mane of Otaria jubata; +on the sub-orbital pits of Ruminants; +on the colours of the sexes in Otaria nigrescens. + +Murray, A., on the Pediculi of different races of men. + +Murray, T.A., on the fertility of Australian women with white men. + +Mus coninga. + +Mus minutus, sexual difference in the colour of. + +Musca vomitoria. + +Muscicapa grisola. + +Muscicapa luctuosa. + +Muscicapa ruticilla, breeding in immature plumage. + +Muscle, ischio-pubic. + +Muscles, rudimentary, occurrence of, in man; +variability of the; +effects of use and disuse upon; +animal-like abnormalities of, in man; +correlated variation of, in the arm and leg; +variability of, in the hands and feet; +of the jaws, influence of, on the physiognomy of the Apes; +habitual spasms of, causing modifications of the facial bones, of the early +progenitors of man; +greater variability of the, in men than in women. + +Musculus sternalis, Prof. Turner on the. + +Music, of birds; +discordant, love of savages for; +reason of power of perception of notes in animals; +power of distinguishing notes; +its connection with primeval speech; +different appreciation of, by different peoples; +origin of; +effects of. + +Musical cadences, perception of, by animals; +powers of man. + +Musk-deer, canine teeth of male; +male, odoriferous organs of the; +winter change of the. + +Musk-duck, Australian; +large size of male; +of Guiana, pugnacity of the male. + +Musk-ox, horns of. + +Musk-rat, protective resemblance of the, to a clod of earth. + +Musophagae, colours and nidification of the; +both sexes of, equally brilliant. + +Mussels opened by monkeys. + +Mustela, winter change of two species of. + +Musters, Captain, on Rhea Darwinii; +marriages amongst Patagonians. + +Mutilations, healing of; +inheritance of. + +Mutilla europaea, stridulation of. + +Mutillidae, absence of ocelli in female. + +Mycetes caraya, polygamous; +vocal organs of; +beard of; +sexual differences of colour in; +voice of. + +Mycetes seniculus, sexual differences of colour in. + +Myriapoda. + +Nageli, on the influence of natural selection on plants; +on the gradation of species of plants. + +Nails, coloured yellow or purple in part of Africa. + +Narwhal, tusks of the. + +Nasal cavities, large size of, in American aborigines. + +Nascent organs. + +Nathusius, H. von, on the improved breeds of pigs; +male domesticated animals more variable than females; +horns of castrated sheep; +on the breeding of domestic animals. + +Natural selection, its effects on the early progenitors of man; +influence of, on man; +limitation of the principle; +influence of, on social animals; +Mr. Wallace on the limitation of, by the influence of the mental faculties +in man; +influence of, in the progress of the United States; +in relation to sex. + +Natural and sexual selection contrasted. + +Naulette, jaw from, large size of the canines in. + +Neanderthal skull, capacity of the. + +Neck, proportion of, in soldiers and sailors. + +Necrophorus, stridulation of. + +Nectarinia, young of. + +Nectariniae, moulting of the; +nidification of. + +Negro, resemblance of a, to Europeans in mental characters. + +Negro-women, their kindness to Mungo Park. + +Negroes, Caucasian features in; +character of; +lice of; +fertility of, when crossed with other races; +blackness of; +variability of; +immunity of, from yellow fever; +difference of, from Americans; +disfigurements of the; +colour of new-born children of; +comparative beardlessness of; +readily become musicians; +appreciation of beauty of their women by; +idea of beauty among; +compression of the nose by some. + +Nemertians, colours of. + +Neolithic period. + +Neomorpha, sexual difference of the beak in. + +Nephila, size of male. + +Nests, made by fishes; +decoration of, by Humming-birds. + +Neumeister, on a change of colour in pigeons after several moultings. + +Neuration, difference of, in the two sexes of some butterflies and +hymenoptera. + +Neuroptera. + +Neurothemis, dimorphism in. + +New Zealand, expectation by the natives of, of their extinction; +practice of tattooing in; +aversion of natives of, to hairs on the face; +pretty girls engrossed by the chiefs in. + +Newton, A., on the throat-pouch of the male bustard; +on the differences between the females of two species of Oxynotus; +on the habits of the Phalarope, dotterel, and godwit. + +Newts. + +Nicholson, Dr., on the non-immunity of dark Europeans from yellow fever. + +Nictitating membrane. + +Nidification of fishes; +relation of, to colour; +of British birds. + +Night-heron, cries of the. + +Nightingale, arrival of the male before the female; +object of the song of the. + +Nightingales, new mates found by. + +Nightjar, selection of a mate by the female; +Australian, sexes of; +coloration of the. + +Nightjars, noise made by some male, with their wings; +elongated feathers in. + +Nilghau, sexual differences of colour in the. + +Nilsson, Prof., on the resemblance of stone arrow-heads from various +places; +on the development of the horns of the reindeer. + +Nipples, absence of, in Monotremata. + +Nitsche, Dr., ear of foetal orang. + +Nitzsch, C.L., on the down of birds. + +Noctuae, brightly-coloured beneath. + +Noctuidae, coloration of. + +Nomadic habits, unfavourable to human progress. + +Nordmann, A., on Tetrao urogalloides. + +Norfolk Island, half-breeds on. + +Norway, numerical proportion of male and female births in. + +Nose, resemblance of, in man and the apes; +piercing and ornamentation of the; +very flat, not admired in negroes; +flattening of the. + +Nott and Gliddon, on the features of Rameses II.; +on the features of Amunoph III.; +on skulls from Brazilian caves; +on the immunity of negroes and mulattoes from yellow fever; +on the deformation of the skull among American tribes. + +Novara, voyage of the, suicide in New Zealand. + +Nudibranch Mollusca, bright colours of. + +Numerals, Roman. + +Nunemaya, natives of, bearded. + +Nuthatch, of Japan, intelligence of; +Indian. + +Obedience, value of. + +Observation, powers of, possessed by birds. + +Occupations, sometimes a cause of diminished stature; +effect of, upon the proportions of the body. + +Ocelli, absence of, in female Mutilidae. + +Ocelli of birds, formation and variability of the. + +Ocelot, sexual differences in the colouring of the. + +Ocyhaps lophotes. + +Odonata. + +Odonestis potatoria, sexual difference of colour in. + +Odour, correlation of, with colour of skin; +of moths; +emitted by snakes in the breeding season; +of mammals. + +Oecanthus nivalis, difference of colour in the sexes of. + +Oecanthus pellucidus. + +Ogle, Dr. W., relation between colour and power of smell. + +Oidemia. + +Oliver, on sounds produced by Pimelia striata. + +Omaloplia brunnea, stridulation of. + +Onitis furcifer, processes of anterior femora of the male, and on the head +and thorax of the female. + +Onthophagus. + +Onthophagus rangifer, sexual differences of; +variations in the horns of the male. + +Ophidia, sexual differences of. + +Ophidium. + +Opossum, wide range of, in America. + +Optic nerve, atrophy of the, caused by destruction of the eye. + +Orang-Outan, Bischoff on the agreement of the brain of the, with that of +man; +adult age of the; +ears of the; +vermiform appendage of; +hands of the; +absence of mastoid processes in the; +platforms built by the; +alarmed at the sight of a turtle; +using a stick as a lever; +using missiles; +using the leaves of the Pandanus as a night covering; +direction of the hair on the arms of the; +its aberrant characters; +supposed evolution of the; +voice of the; +monogamous habits of the; +male, beard of the. + +Oranges, treatment of, by monkeys. + +Orange-tip butterfly. + +Orchestia Darwinii, dimorphism of males of. + +Orchestia Tucuratinga, limbs of. + +Ordeal, trial by. + +Oreas canna, colours of. + +Oreas Derbianus, colours of. + +Organs, prehensile; +utilised for new purposes. + +Organic scale, von Baer's definition of progress in. + +Orioles, nidification of. + +Oriolus, species of, breeding in immature plumage. + +Oriolus melanocephalus, coloration of the sexes in. + +Ornaments, prevalence of similar; +of male birds; +fondness of savages for. + +Ornamental characters, equal transmission of, to both sexes, in mammals; +of monkeys. + +Ornithoptera croesus. + +Ornithorhynchus, reptilian tendency of; +spur of the male. + +Orocetes erythrogastra, young of. + +Orrony, Grotto of. + +Orsodacna atra, difference of colour in the sexes of. + +Orsodacna ruficollis. + +Orthoptera, metamorphosis of; +stridulating apparatus of; +colours of; +rudimentary stridulating organs in female; +stridulation of the, and Homoptera, discussed. + +Ortygornis gularis, pugnacity of the male. + +Oryctes, stridulation of; +sexual differences in the stridulant organs of. + +Oryx leucoryx, use of the horns of. + +Osphranter rufus, sexual difference in the colour of. + +Ostrich, African, sexes and incubation of the. + +Ostriches, stripes of young. + +Otaria jubata, mane of the male. + +Otaria nigrescens, difference in the coloration of the sexes of. + +Otis bengalensis, love-antics of the male. + +Otis tarda, throat-pouch of the male; +polygamous. + +Ouzel, ring-, colours and nidification of the. + +Ouzel, water-, singing in the autumn; +colours and nidification of the. + +Ovibos moschatus, horns of. + +Ovipositor of insects. + +Ovis cycloceros, mode of fighting of. + +Ovule of man. + +Owen, Prof., on the Corpora Wolffiana; +on the great toe in man; +on the nictitating membrane and semilunar fold; +on the development of the posterior molars in different races of man; +on the length of the caecum in the Koala; +on the coccygeal vertebrae; +on rudimentary structures belonging to the reproductive system; +on abnormal conditions of the human uterus; +on the number of digits in the Ichthyopterygia; +on the canine teeth in man; +on the walking of the chimpanzee and orang; +on the mastoid processes in the higher apes; +on the hairiness of elephants in elevated districts; +on the caudal vertebrae of monkeys; +classification of mammalia; +on the hair in monkeys; +on the piscine affinities of the Ichthyosaurians; +on polygamy and monogamy among the antelopes; +on the horns of Antilocapra Americana; +on the musky odour of crocodiles during the breeding season; +on the scent-glands of snakes; +on the Dugong, Cachalot, and Ornithorhynchus; +on the antlers of the red deer; +on the dentition of the Camelidae; +on the horns of the Irish elk; +on the voice of the giraffe, porcupine, and stag; +on the laryngeal sac of the gorilla and orang; +on the odoriferous glands of mammals; +on the effects of emasculation on the vocal organs of men; +on the voice of Hylobates agilis; +on American monogamous monkeys. + +Owls, white, new mates found by. + +Oxynotus, difference of the females of two species of. + +Pachydermata. + +Pachytylus migratorius. + +Paget, on the abnormal development of hairs in man; +on the thickness of the skin on the soles of the feet of infants. + +Pagurus, carrying the female. + +Painting, pleasure of savages in. + +Palaemon, chelae of a species of. + +Palaeornis, sexual differences of colour in. + +Palaeornis javanicus, colour of beak of. + +Palaeornis rosa, young of. + +Palamedea cornuta, spurs on the wings. + +Paleolithic period. + +Palestine, habits of the chaffinch in. + +Pallas, on the perfection of the senses in the Mongolians; +on the want of connexion between climate and the colour of the skin; +on the polygamous habits of Antilope Saiga; +on the lighter colour of horses and cattle in winter in Siberia; +on the tusks of the musk-deer; +on the odoriferous glands of mammals; +on the odoriferous glands of the musk-deer; +on winter changes of colour in mammals; +on the ideal of female beauty in North China. + +Palmaris accessorius, muscle variations of the. + +Pampas, horses of the. + +Pangenesis, hypothesis of. + +Panniculus carnosus. + +Pansch, on the brain of a foetal Cebus apella. + +Papilio, proportion of the sexes in North American species of; +sexual differences of colouring in species of; +coloration of the wings in species of. + +Papilio ascanius. + +Papilio Sesostris and Childrenae, variability of. + +Papilio Turnus. + +Papilionidae, variability in the. + +Papuans, line of separation between the, and the Malays; +beards of the; +teeth of. + +Papuans and Malays, contrast in characters of. + +Paradise, Birds of; +supposed by Lesson to be polygamous; +rattling of their quills by; +racket-shaped feathers in; +sexual differences in colour of; +decomposed feathers in; +display of plumage by the male; +sexual differences in colour of. + +Paradisea apoda, barbless feathers in the tail of; +plumage of; +and P. papuana; +divergence of the females of; +increase of beauty with age. + +Paradisea papuana, plumage of. + +Paraguay, Indians of, eradication of eyebrows and eyelashes by. + +Parallelism of development of species and languages. + +Parasites, on man and animals; +as evidence of specific identity or distinctness; +immunity from, correlated with colour. + +Parental feeling in earwigs, starfishes, and spiders; +affection, partly a result of natural selection. + +Parents, age of, influence upon sex of offspring. + +Parinae, sexual difference of colour in. + +Park, Mungo, negro-women teaching their children to love the truth; +his treatment by the negro-women; +on negro opinions of the appearance of white men. + +Parker, Mr., no bird or reptile in line of mammalian descent. + +Parrakeet, young of; +Australian, variation in the colour of the thighs of a male. + +Parrot, racket-shaped feathers in the tail of a; +instance of benevolence in a. + +Parrots, change of colour in; +imitative faculties of; +living in triplets; +affection of; +colours and nidification of the; +immature plumage of the; +colours of; +sexual differences of colour in; +musical powers of. + +Parthenogenesis in the Tenthredinae; +in Cynipidae; +in Crustacea. + +Partridge, monogamous; +proportion of the sexes in the; +Indian; +female. + +Partridge-"dances." + +Partridges, living in triplets; +spring coveys of male; +distinguishing persons. + +Parus coeruleus. + +Passer, sexes and young of. + +Passer brachydactylus. + +Passer domesticus. + +Passer montanus. + +Patagonians, self-sacrifice by; +marriages of. + +Patterson, Mr., on the Agrionidae. + +Patteson, Bishop, decrease of Melanesians. + +Paulistas of Brazil. + +Pavo cristatus. + +Pavo muticus, possession of spurs by the female. + +Pavo nigripennis. + +Payaguas Indians, thin legs and thick arms of the. + +Payan, Mr., on the proportion of the sexes in sheep. + +Peacock, polygamous; +sexual characters of; +pugnacity of the; +Javan, possessing spurs; +rattling of the quills by; +elongated tail-coverts of the; +love of display of the; +ocellated spots of the; +inconvenience of long tail of the, to the female; +continued increase of beauty of the. + +Peacock-butterfly. + +Peafowl, preference of females for a particular male; +first advances made by the female. + +Pediculi of domestic animals and man. + +Pedigree of man. + +Pedionomus torquatus, sexes of. + +Peel, J., on horned sheep. + +Peewit, wing-tubercles of the male. + +Pelagic animals, transparency of. + +Pelecanus erythrorhynchus, horny crest on the beak of the male, during the +breeding season. + +Pelecanus onocrotalus, spring plumage of. + +Pelele, an African ornament. + +Pelican, blind, fed by his companions; +young, guided by old birds; +pugnacity of the male. + +Pelicans, fishing in concert. + +Pelobius Hermanni, stridulation of. + +Pelvis, alteration of, to suit the erect attitude of man; +differences of the, in the sexes of man. + +Penelope nigra, sound produced by the male. + +Pennant, on the battles of seals; +on the bladder-nose seal. + +Penthe, antennal cushions of the male. + +Perch, brightness of male, during breeding season. + +Peregrine falcon, new mate found by. + +Period of variability, relation of, to sexual selection. + +Periodicity, vital, Dr. Laycock on. + +Periods, lunar, followed by functions in man and animals. + +Periods of life, inheritance at corresponding. + +Perisoreus canadensis, young of. + +Peritrichia, difference of colour in the sexes of a species of. + +Periwinkle. + +Pernis cristata. + +Perrier, M., on sexual selection; +on bees. + +Perseverance, a characteristic of man. + +Persians, said to be improved by intermixture with Georgians and +Circassians. + +Personnat, M., on Bombyx Yamamai. + +Peruvians, civilisation of the, not foreign. + +Petrels, colours of. + +Petrocincla cyanea, young of. + +Petrocossyphus. + +Petronia. + +Pfeiffer, Ida, on Javan ideas of beauty. + +Phacochoerus aethiopicus, tusks and pads of. + +Phalanger, Vulpine, black varieties of the. + +Phalaropus fulicarius. + +Phalaropus hyperboreus. + +Phanaeus. + +Phanaeus carnifex, variation of the horns of the male. + +Phanaeus faunus, sexual differences of. + +Phanaeus lancifer. + +Phaseolarctus cinereus, taste for rum and tobacco. + +Phasgonura viridissima, stridulation of. + +Phasianus Soemmerringii. + +Phasianus versicolor. + +Phasianus Wallichii. + +Pheasant, polygamous; +and black grouse, hybrids of; +production of hybrids with the common fowl; +immature plumage of the. + +Pheasant, Amherst, display of. + +Pheasant, Argus, display of plumage by the male; +ocellated spots of the; +gradation of characters in the. + +Pheasant, Blood- + +Pheasant, Cheer. + +Pheasant, Eared, length of the tail in the; +sexes alike in the. + +Pheasant, Fire-backed, possessing spurs. + +Pheasant, Golden, display of plumage by the male; +age of mature plumage in the; +sex of young, ascertained by pulling out head-feathers. + +Pheasant, Kalij, drumming of the male. + +Pheasant, Reeve's, length of the tail in. + +Pheasant, Silver, triumphant male, deposed on account of spoiled plumage; +sexual coloration of the. + +Pheasant, Soemmerring's. + +Pheasant, Tragopan, display of plumage by the male; +marking of the sexes of the. + +Pheasants, period of acquisition of male characters in the family of the; +proportion of sexes in chicks of; +length of the tail in. + +Philters, worn by women. + +Phoca groenlandica, sexual difference in the coloration of. + +Phoenicura ruticilla. + +Phosphorescence of insects. + +Phryganidae, copulation of distinct species of. + +Phryniscus nigricans. + +Physical inferiority, supposed, of man. + +Pickering, on the number of species of man. + +Picton, J.A., on the soul of man. + +Picus auratus. + +Picus major. + +Pieris. + +Pigeon, female, deserting a weakened mate; +carrier, late development of the wattle in; +pouter, late development of crop in; +domestic, breeds and sub-breeds of. + +Pigeons, nestling, fed by the secretion of the crop of both parents; +changes of plumage in; +transmission of sexual peculiarities in; +Belgian, with black-streaked males; +changing colour after several moultings; +numerical proportion of the sexes in; +cooing of; +variations in plumage of; +display of plumage by male; +local memory of; +antipathy of female, to certain males; +pairing of; +profligate male and female; +wing-bars and tail-feathers of; +supposititious breed of; +pouter and carrier, peculiarities of, predominant in males; +nidification of; +Australian; +immature plumage of the. + +Pigs, origin of the improved breeds of; +numerical proportion of the sexes in; +stripes of young; +tusks of miocene; +sexual preference shewn by. + +Pike, American, brilliant colours of the male, during the breeding season. + +Pike, reasoning powers of; +male, devoured by females. + +Pike, L.O., on the psychical elements of religion. + +Pimelia striata, sounds produced by the female. + +Pinel, hairiness in idiots. + +Pintail, drake, plumage of; +pairing with a wild duck. + +Pintail Duck, pairing with a widgeon. + +Pipe-fish, filamentous; +marsupial receptacles of the male. + +Pipits, moulting of the. + +Pipra, modified secondary wing-feathers of male. + +Pipra deliciosa. + +Pirates stridulus, stridulation of. + +Pitcairn island, half-breeds on. + +Pithecia leucocephala, sexual differences of colour in. + +Pithecia Satanas, beard of; +resemblance of, to a negro. + +Pits, suborbital, of Ruminants. + +Pittidae, nidification of. + +Placentata. + +Plagiostomous fishes. + +Plain-wanderer, Australian. + +Planariae, bright colours of some. + +Plantain-eaters, colours and nidification of the; +both sexes of, equally brilliant. + +Plants, cultivated, more fertile than wild; +Nageli, on natural selection in; +male flowers of, mature before the female; +phenomena of fertilisation in. + +Platalea, change of plumage in. + +Platyblemus. + +Platycercus, young of. + +Platyphyllum concavum. + +Platyrrhine monkeys. + +Platysma myoides. + +Plecostomus, head-tentacles of the males of a species of. + +Plecostomus barbatus, peculiar beard of the male. + +Plectropterus gambensis, spurred wings of. + +Ploceus. + +Plovers, wing-spurs of; +double moult in. + +Plumage, changes of, inheritance of, by fowls; +tendency to analogous variation in; +display of, by male birds; +changes of, in relation to season; +immature, of birds; +colour of, in relation to protection. + +Plumes on the head in birds, difference of, in the sexes. + +Pneumora, structure of. + +Podica, sexual difference in the colour of the irides. + +Poeppig, on the contact of civilised and savage races. + +Poison, avoidance of, by animals. + +Poisonous fruits and herbs avoided by animals. + +Poisons, immunity from, correlated with colour. + +Polish fowls, origin of the crest in. + +Pollen and van Dam, on the colours of Lemur macaco. + +Polyandry, in certain Cyprinidae; +among the Elateridae. + +Polydactylism in man. + +Polygamy, influence of, upon sexual selection; +superinduced by domestication; +supposed increase of female births by. +In the stickleback. + +Polygenists. + +Polynesia, prevalence of infanticide in. + +Polynesians, wide geographical range of; +difference of stature among the; +crosses of; +variability of; +heterogeneity of the; +aversion of, to hairs on the face. + +Polyplectron, number of spurs in; +display of plumage by the male; +gradation of characters in; +female of. + +Polyplectron chinquis. + +Polyplectron Hardwickii. + +Polyplectron malaccense. + +Polyplectron Napoleonis. + +Polyzoa. + +Pomotis. + +Pontoporeia affinis. + +Porcupine, mute, except in the rutting season. + +Pores, excretory, numerical relation of, to the hairs in sheep. + +Porpitae, bright colours of some. + +Portax picta, dorsal crest and throat-tuft of; +sexual differences of colour in. + +Portunus puber, pugnacity of. + +Potamochoerus pencillatus, tusks and facial knobs of the. + +Pouchet, G., the relation of instinct to intelligence; +on the instincts of ants; +on the caves of Abou-Simbel; +on the immunity of negroes from yellow fever; +change of colour in fishes. + +Pouter pigeon, late development of the large crop in. + +Powell, Dr., on stridulation. + +Power, Dr., on the different colours of the sexes in a species of Squilla. + +Powys, Mr., on the habits of the chaffinch in Corfu. + +Pre-eminence of man. + +Preference for males by female birds; +shewn by mammals, in pairing. + +Prehensile organs. + +Presbytis entellus, fighting of the male. + +Preyer, Dr., on function of shell of ear; +on supernumerary mammae in women. + +Prichard, on the difference of stature among the Polynesians; +on the connection between the breadth of the skull in the Mongolians and +the perfection of their senses; +on the capacity of British skulls of different ages; +on the flattened heads of the Colombian savages; +on Siamese notions of beauty; +on the beardlessness of the Siamese; +on the deformation of the head among American tribes and the natives of +Arakhan. + +Primary sexual organs. + +Primates, sexual differences of colour in. + +Primogeniture, evils of. + +Prionidae, difference of the sexes in colour. + +Proctotretus multimaculatus. + +Proctotretus tenuis, sexual difference in the colour of. + +Profligacy. + +Progenitors, early, of man. + +Progress, not the normal rule in human society; +elements of. + +Prong-horn antelope, horns of. + +Proportions, difference of, in distinct races. + +Protective colouring in butterflies; +in lizards; +in birds; +in mammals. + +Protective nature of the dull colouring of female Lepidoptera. + +Protective resemblances in fishes. + +Protozoa, absence of secondary sexual characters in. + +Pruner-Bey, on the occurrence of the supra-condyloid foramen in the humerus +of man; +on the colour of negro infants. + +Prussia, numerical proportion of male and female births in. + +Psocus, proportions of the sexes in. + +Ptarmigan, monogamous; +summer and winter plumage of the; +nuptial assemblages of; +triple moult of the; +protective coloration of. + +Puff-birds, colours and nidification of the. + +Pugnacity of fine-plumaged male birds. + +Pumas, stripes of young. + +Puppies learning from cats to clean their faces. + +Pycnonotus haemorrhous, pugnacity of the male; +display of under-tail coverts by the male. + +Pyranga aestiva, male aiding in incubation; +male characters in female of. + +Pyrodes, difference of the sexes in colour. + +Quadrumana, hands of; +differences between man and the; +sexual differences of colour in; +ornamental characters of; +analogy of sexual differences of, with those of man; +fighting of males for the females; +monogamous habits of; +beards of the. + +Quain, R., on the variation of the muscles in man. + +Quatrefages, A. de, on the occurrence of a rudimentary tail in man; +on variability; +on the moral sense as a distinction between man and animals; +civilised men stronger than savages; +on the fertility of Australian women with white men; +on the Paulistas of Brazil; +on the evolution of the breeds of cattle; +on the Jews; +on the liability of negroes to tropical fevers after residence in a cold +climate; +on the difference between field- and house-slaves; +on the influence of climate on colour; +colours of annelids; +on the Ainos; +on the women of San Giuliano. + +Quechua, see Quichua. + +Querquedula acuta. + +Quetelet, proportion of sexes in man; +relative size in man and woman. + +Quichua Indians; +local variation of colour in the; +no grey hair among the; +hairlessness of the; +long hair of the. + +Quiscalus major, proportions of the sexes of, in Florida and Honduras. + +Rabbit, white tail of the. + +Rabbits, domestic, elongation of the skull in; +modification of the skull in, by the lopping of the ear; +danger-signals of; +numerical proportion of the sexes in. + +Races, distinctive characters of; +or species of man; +crossed, fertility or sterility of; +of man, variability of the; +of man, resemblance of, in mental characters; +formation of; +of man, extinction of; +effects of the crossing of; +of man, formation of the; +of man, children of the; +beardless, aversion of, to hairs on the face. + +Raffles, Sir S., on the banteng. + +Rafts, use of. + +Rage, manifested by animals. + +Raia batis, teeth of. + +Raia clavata, female spined on the back; +sexual difference in the teeth of. + +Raia maculata, teeth of. + +Rails, spur-winged. + +Ram, mode of fighting of the; +African, mane of an; +fat-tailed. + +Rameses II., features of. + +Ramsay, Mr., on the Australian musk-duck; +on the regent-bird; +on the incubation of Menura superba. + +Rana esculenta, vocal sacs of. + +Rat, common, general dispersion of, a consequence of superior cunning; +supplantation of the native in New Zealand, by the European rat; +common, said to be polygamous; +numerical proportion of the sexes in. + +Rats, enticed by essential oils. + +Rationality of birds. + +Rattlesnakes, difference of the sexes in the; +rattles as a call. + +Raven, vocal organs of the; +stealing bright objects; +pied, of the Feroe Islands. + +Rays, prehensile organs of male. + +Razor-bill, young of the. + +Reade, Winwood, suicide among savages in Africa; +mulattoes not prolific; +effect of castration of horned sheep; +on the Guinea sheep; +on the occurrence of a mane in an African ram; +on singing of negroes; +on the negroes' appreciation of the beauty of their women; +on the admiration of negroes for a black skin; +on the idea of beauty among negroes; +on the Jollofs; +on the marriage-customs of the negroes. + +Reason in animals. + +Redstart, American, breeding in immature plumage. + +Redstarts, new mates found by. + +Reduvidae, stridulation of. + +Reed-bunting, head-feathers of the male; +attacked by a bullfinch. + +Reefs, fishes frequenting. + +Reeks, H., retention of horns by breeding deer; +cow rejected by a bull; +destruction of piebald rabbits by cats. + +Regeneration, partial, of lost parts in man. + +Regent bird. + +Reindeer, horns of the; +battles of; +horns of the female; +antlers of, with numerous points; +winter change of the; +sexual preferences shown by. + +Relationship, terms of. + +Religion, deficiency of among certain races; +psychical elements of. + +Remorse, deficiency of, among savages. + +Rengger, on the diseases of Cebus Azarae; +on the diversity of the mental faculties of monkeys; +on the Payaguas Indians; +on the inferiority of Europeans to savages in their senses; +revenge taken by monkeys; +on maternal affection in a Cebus; +on the reasoning powers of American monkeys; +on the use of stones by monkeys for cracking hard nuts; +on the sounds uttered by Cebus Azarae; +on the signal-cries of monkeys; +on the polygamous habits of Mycetes caraya; +on the voice of the howling monkeys; +on the odour of Cervus campestris; +on the beards of Mycetes caraya and Pithecia Satanas; +on the colours of Felis mitis; +on the colours of Cervus paludosus; +on sexual differences of colour in Mycetes; +on the colour of the infant Guaranys; +on the early maturity of the female of Cebus Azarae; +on the beards of the Guaranys; +on the emotional notes employed by monkeys; +on American polygamous monkeys. + +Representative species, of birds. + +Reproduction, unity of phenomena of, throughout the mammalia; +period of, in birds. + +Reproductive system, rudimentary structures in the; +accessory parts of. + +Reptiles. + +Reptiles and birds, alliance of. + +Resemblances, small, between man and the apes. + +Retrievers, exercise of reasoning faculties by. + +Revenge, manifested by animals. + +Reversion, perhaps the cause of some bad dispositions. + +Rhagium, difference of colour in the sexes of a species of. + +Rhamphastos carinatus. + +Rhea Darwinii. + +Rhinoceros, nakedness of; +horns of; +horns of, used defensively; +attacking white or grey horses. + +Rhynchaea, sexes and young of. + +Rhynchaea australis. + +Rhynchaea bengalensis. + +Rhynchaea capensis. + +Rhythm, perception of, by animals. + +Richard, M., on rudimentary muscles in man. + +Richardson, Sir J., on the pairing of Tetrao umbellus; +on Tetrao urophasianus; +on the drumming of grouse; +on the dances of Tetrao phasianellus; +on assemblages of grouse; +on the battles of male deer; +on the reindeer; +on the horns of the musk-ox; +on antlers of the reindeer with numerous points; +on the moose; +on the Scotch deerhound. + +Richter, Jean Paul, on imagination. + +Riedel, on profligate female pigeons. + +Riley, Mr., on mimicry in butterflies; +bird's disgust at taste of certain caterpillars. + +Ring-ouzel, colours and nidification of the. + +Ripa, Father, on the difficulty of distinguishing the races of the Chinese. + +Rivalry, in singing, between male birds. + +River-hog, African, tusks and knobs of the. + +Rivers, analogy of, to islands. + +Roach, brightness of the male during breeding-season. + +Robbery, of strangers, considered honourable. + +Robertson, Mr., remarks on the development of the horns in the roebuck and +red deer. + +Robin, pugnacity of the male; +autumn song of the; +female singing of the; +attacking other birds with red in their plumage; +young of the. + +Robinet, on the difference of size of the male and female cocoons of the +silk-moth. + +Rodents, uterus in the; +absence of secondary sexual characters in; +sexual differences in the colours of. + +Roe, winter changes of the. + +Rohfs, Dr., Caucasian features in negro; +fertility of mixed races in Sahara; +colours of birds in Sahara; +ideas of beauty amongst the Bornuans. + +Rolle, F., on the origin of man; +on a change in German families settled in Georgia. + +Roller, harsh cry of. + +Romans, ancient, gladiatorial exhibitions of the. + +Rook, voice of the. + +Rossler, Dr., on the resemblance of the lower surface of butterflies to the +bark of trees. + +Rostrum, sexual difference in the length of in some weevils. + +Royer, Madlle., mammals giving suck. + +Rudimentary organs, origin of. + +Rudiments, presence of, in languages. + +Rudolphi, on the want of connexion between climate and the colour of the +skin. + +Ruff, supposed to be polygamous; +proportion of the sexes in the; +pugnacity of the; +double moult in; +duration of dances of; +attraction of the, to bright objects. + +Ruminants, male, disappearance of canine teeth in; +generally polygamous; +suborbital pits of; +sexual differences of colour in. + +Rupicola crocea, display of plumage by the male. + +Ruppell, on canine teeth in deer and antelopes. + +Russia, numerical proportion of male and female births in. + +Ruticilla. + +Rutimeyer, Prof., on the physiognomy of the apes; +on tusks of miocene boar; +on the sexual differences of monkeys. + +Rutlandshire, numerical proportion of male and female births in. + +Sachs, Prof., on the behaviour of the male and female elements in +fertilisation. + +Sacrifices, human. + +Sagittal crest, in male apes and Australians. + +Sahara, fertility of mixed races in; +birds of the; +animal inhabitants of the. + +Sailors, growth of, delayed by conditions of life; +long-sighted. + +Sailors and soldiers, difference in the proportions of. + +St. John, Mr., on the attachment of mated birds. + +St. Kilda, beards of the inhabitants of. + +Salmo eriox, and Salmo umbla, colouring of the male, +during the breeding season. + +Salmo lycaodon. + +Salmo salar. + +Salmon, leaping out of fresh water; +male, ready to breed before the female; +proportion of the sexes in; +male, pugnacity of the; +male, characters of, during the breeding season; +spawning of the; +breeding of immature male. + +Salvin, O., inheritance of mutilated feathers; +on the Humming-birds; +on the numerical proportion of the sexes in Humming-birds; +on Chamaepetes and Penelope; +on Selasphorus platycercus; +Pipra deliciosa; +on Chasmorhynchus. + +Samoa Islands, beardlessness of the natives of. + +Sandhoppers, claspers of male. + +Sand-skipper. + +Sandwich Islands, variation in the skulls of the natives of the; +decrease of native population; +population of; +superiority of the nobles in the. + +Sandwich Islanders, lice of. + +San-Giuliano, women of. + +Santali, recent rapid increase of the; +Mr. Hunter on the. + +Saphirina, characters of the males of. + +Sarkidiornis melanonotus, characters of the young. + +Sars, O., on Pontoporeia affinis. + +Saturnia carpini, attraction of males by the female. + +Saturnia Io, difference of coloration in the sexes of. + +Saturniidae, coloration of the. + +Savage, Dr., on the fighting of the male gorillas; +on the habits of the gorilla. + +Savage and Wyman on the polygamous habits of the gorilla. + +Savages, uniformity of, exaggerated; +long-sighted; +rate of increase among, usually small; +retention of the prehensile power of the feet by; +imitative faculties of; +causes of low morality of; +tribes of, supplanting one another; +improvements in the arts among; +arts of; +fondness of, for rough music; +on long-enduring fashions among; +attention paid by, to personal appearance; +relation of the sexes among. + +Saviotti, Dr., division of malar bone. + +Saw-fly, pugnacity of a male. + +Saw-flies, proportions of the sexes in. + +Saxicola rubicola, young of. + +Scalp, motion of the. + +Scent-glands in snakes. + +Schaaffhausen, Prof., on the development of the posterior molars in +different races of man; +on the jaw from La Naulette; +on the correlation between muscularity and prominent supra-orbital ridges; +on the mastoid processes of man; +on modifications of the cranial bones; +on human sacrifices; +on the probable speedy extermination of the anthropomorphous apes; +on the ancient inhabitants of Europe; +on the effects of use and disuse of parts; +on the superciliary ridge in man; +on the absence of race-differences in the infant skull in man; +on ugliness. + +Schaum, H., on the elytra of Dytiscus and Hydroporus. + +Scherzer and Schwarz, measurements of savages. + +Schelver, on dragon-flies. + +Schiodte, on the stridulation of Heterocerus. + +Schlegel, F. von, on the complexity of the languages of uncivilised +peoples. + +Schlegel, Prof., on Tanysiptera. + +Schleicher, Prof, on the origin of language. + +Schomburgk, Sir R., on the pugnacity of the male musk-duck of Guiana; +on the courtship of Rupicola crocea. + +Schoolcraft, Mr., on the difficulty of fashioning stone implements. + +Schopenhauer, on importance of courtship to mankind. + +Schweinfurth, complexion of negroes. + +Sciaena aquila. + +Sclater, P.L., on modified secondary wing-feathers in the males of Pipra; +on elongated feathers in nightjars; +on the species of Chasmorhynchus; +on the plumage of Pelecanus onocrotalus; +on the plantain-eaters; +on the sexes and young of Tadorna variegata; +on the colours of Lemur macaco; +on the stripes in asses. + +Scolecida, absence of secondary sexual characters in. + +Scolopax frenata, tail feathers of; + +Scolopax gallinago, drumming of. + +Scolopax javensis, tail-feathers of. + +Scolopax major, assemblies of. + +Scolopax Wilsonii, sound produced by. + +Scolytus, stridulation of. + +Scoter-duck, black, sexual difference in coloration of the; +bright beak of male. + +Scott, Dr., on idiots smelling their food. + +Scott, J., on the colour of the beard in man. + +Scrope, on the pugnacity of the male salmon; +on the battles of stags. + +Scudder, S.H., imitation of the stridulation of the Orthoptera; +on the stridulation of the Acridiidae; +on a Devonian insect; +on stridulation. + +Sculpture, expression of the ideal of beauty by. + +Sea-anemones, bright colours of. + +Sea-bear, polygamous. + +Sea-elephant, male, structure of the nose of the; +polygamous. + +Sea-lion, polygamous. + +Seal, bladder-nose. + +Seals, their sentinels generally females; +evidence furnished by, on classification; +polygamous habits of; +battles of male; +canine teeth of male; +sexual differences; +pairing of; +sexual peculiarities of; +in the coloration of; +appreciation of music by. + +Sea-scorpion, sexual differences in. + +Season, changes of colour in birds, in accordance with the; +changes of plumage of birds in relation to. + +Seasons, inheritance at corresponding. + +Sebituani, African chief, trying to alter a fashion. + +Sebright Bantam. + +Secondary sexual characters; +relations of polygamy to; +transmitted through both sexes; +gradation of, in birds. + +Sedgwick, W., on hereditary tendency to produce twins. + +Seemann, Dr., on the different appreciation of music by different peoples; +on the effects of music. + +Seidlitz, on horns of reindeer. + +Selasphorus platycercus, acuminate first primary of the male. + +Selby, P.J., on the habits of the black and red grouse. + +Selection as applied to primeval man. + +Selection, double. + +Selection, injurious forms of, in civilised nations. + +Selection of male by female birds. + +Selection, methodical, of Prussian grenadiers. + +Selection, sexual, explanation of; +influence of, on the colouring of Lepidoptera. + +Selection, sexual and natural, contrasted. + +Self-command, habit of, inherited; +estimation of. + +Self-consciousness, in animals. + +Self-preservation, instinct of. + +Self-sacrifice, by savages; +estimation of. + +Semilunar fold. + +Semnopithecus, long hair on the heads of species of. + +Semnopithecus chrysomelas, sexual differences of colour in. + +Semnopithecus comatus, ornamental hair on the head of. + +Semnopithecus frontatus, beard etc., of. + +Semnopithecus nasica, nose of. + +Semnopithecus nemaeus, colouring of. + +Semnopithecus rubicundus, ornamental hair on the head of. + +Senses, inferiority of Europeans to savages in the. + +Sentinels, among animals. + +Serpents, instinctively dreaded by apes and monkeys. + +Serranus, hermaphroditism in. + +Setina, noise produced by. + +Sex, inheritance limited by. + +Sexes, relative proportions of, in man; +proportions of, sometimes influenced by selection; +probable relation of the, in primeval man. + +Sexual and natural selection, contrasted. + +Sexual characters, effects of the loss of; +limitation of. + +Sexual characters, secondary; +relations of polygamy to; +transmitted through both sexes; +gradation of, in birds. + +Sexual differences in man. + +Sexual selection, explanation of; +influence of, on the colouring of Lepidoptera; +objections to; +action of, in mankind. + +Sexual selection in spiders. + +Sexual selection, supplemental note on. + +Sexual similarity. + +Shaler, Prof., sizes of sexes in whales. + +Shame. + +Sharks, prehensile organs of male. + +Sharpe, Dr., Europeans in the tropics. + +Sharpe, R.B., on Tanysiptera sylvia; +on Ceryle; +on the young male of Dacelo Gaudi-chaudi. + +Shaw, Mr., on the pugnacity of the male salmon. + +Shaw, J., on the decorations of birds. + +Sheep, danger-signals of; +sexual differences in the horns of; +horns of; +domestic, sexual differences of, late developed; +numerical proportion of the sexes in; +inheritance of horns by one sex; +effect of castration; +mode of fighting of; +arched foreheads of some. + +Sheep, Merino, loss of horns in females of; +horns of. + +Shells, difference in form of, in male and female Gasteropoda; +beautiful colours and shapes of. + +Shield-drake, pairing with a common duck; +New Zealand, sexes and young of. + +Shooter, J., on the Kaffirs; +on the marriage-customs of the Kaffirs. + +Shrew-mice, odour of. + +Shrike, Drongo. + +Shrikes, characters of young. + +Shuckard, W.E., on sexual differences in the wings of Hymenoptera. + +Shyness of adorned male birds; + +Siagonium, proportions of the sexes in; +dimorphism in males of. + +Siam, proportion of male and female births in. + +Siamese, general beardlessness of the; +notions of beauty of the; +hairy family of. + +Sidgwick, H., on morality in hypothetical bee community; +our actions not entirely directed by pain and pleasure. + +Siebold, C.T., von, on the proportion of sexes in the Apus; +on the auditory apparatus of the stridulent Orthoptera. + +Sight, inheritance of long and short. + +Signal-cries of monkeys. + +Silk-moth, proportion of the sexes in; +Ailanthus, Prof. Canestrini, on the destruction of its larvae by wasps; +difference of size of the male and female cocoons of the; +pairing of the. + +Simiadae, their origin and divisions. + +Similarity, sexual. + +Singing of the Cicadae and Fulgoridae; +of tree-frogs; +of birds, object of the. + +Sirenia, nakedness of. + +Sirex juvencus. + +Siricidae, difference of the sexes in. + +Siskin, pairing with a canary. + +Sitana, throat-pouch of the males of. + +Size, relative, of the sexes of insects. + +Skin, dark colour of, a protection against heat. + +Skin, movement of the; +nakedness of, in man; +colour of the. + +Skin and hair, correlation of colour of. + +Skull, variation of, in man; +cubic contents of, no absolute test of intellect; +Neanderthal, capacity of the; +causes of modification of the; +difference of, in form and capacity, in different races of men; +variability of the shape of the; +differences of, in the sexes in man; +artificial modification of the shape of. + +Skunk, odour emitted by the; +white tail of, protective. + +Slavery, prevalence of; +of women. + +Slaves, difference between field- and house-slaves. + +Sloth, ornaments of male. + +Smell, sense of, in man and animals. + +Smith, Adam, on the basis of sympathy. + +Smith, Sir A., on the recognition of women by male Cynocephali; +on revenge by a baboon; +on an instance of memory in a baboon; +on the retention of their colour by the Dutch in South Africa; +on the polygamy of the South African antelopes; +on the polygamy of the lion; +on the proportion of the sexes in Kobus ellipsiprymnus; +on Bucephalus capensis; +on South African lizards; +on fighting gnus; +on the horns of rhinoceroses; +on the fighting of lions; +on the colours of the Cape Eland; +on the colours of the gnu; +on Hottentot notions of beauty; +disbelief in communistic marriages. + +Smith, F., on the Cynipidae and Tenthredinidae; +on the relative size of the sexes of Aculeate Hymenoptera; +on the difference between the sexes of ants and bees; +on the stridulation of Trox sabulosus; +on the stridulation of Mononychus pseudacori. + +Smynthurus luteus, courtship of. + +Snakes, sexual differences of; +mental powers of; +male, ardency of. + +"Snarling muscles." + +Snipe, drumming of the; +coloration of the. + +Snipe, painted, sexes and young of. + +Snipe, solitary, assemblies of. + +Snipes, arrival of male before the female; +pugnacity of male; +double moult in. + +Snow-goose, whiteness of the. + +Sociability, the sense of duty connected with; +impulse to, in animals; +manifestations of, in man; +instinct of, in animals. + +Social animals, affection of, for each other; +defence of, by the males. + +Sociality, probable, of primeval men; +influence of, on the development of the intellectual faculties; +origin of, in man. + +Soldiers, American, measurements of. + +Soldiers and sailors, difference in the proportions of. + +Solenostoma, bright colours and marsupial sac of the females of. + +Song, of male birds appreciated by their females; +want of, in brilliant plumaged birds; +of birds. + +Sorex, odour of. + +Sounds, admired alike by man and animals; +produced by fishes; +produced by male frogs and toads; +instrumentally produced by birds. + +Spain, decadence of. + +Sparassus smaragdulus, difference of colour in the sexes of. + +Sparrow, pugnacity of the male; +acquisition of the Linnet's song by a; +coloration of the; +immature plumage of the. + +Sparrow, white-crowned, young of the. + +Sparrows, house- and tree-. + +Sparrows, new mates found by. + +Sparrows, sexes and young of; +learning to sing. + +Spathura Underwoodi. + +Spawning of fishes. + +Spear, used before dispersion of man. + +Species, causes of the advancement of; +distinctive characters of; +or races of man; +sterility and fertility of, when crossed; +supposed, of man; +gradation of; +difficulty of defining; +representative, of birds; +of birds, comparative differences between the sexes of distinct. + +Spectrum femoratum, difference of colour in the sexes of. + +Speech, connection between the brain and the faculty of; +connection of intonation with music. + +Spel, of the black-cock. + +Spencer, Herbert, on the influence of food on the size of the jaws; +on the dawn of intelligence; +on the origin of the belief in spiritual agencies; +on the origin of the moral sense; +on music. + +Spengel, disagrees with explanation of man's hairlessness. + +Sperm-whales, battles of male. + +Sphingidae, coloration of the. + +Sphinx, Humming-bird. + +Sphinx, Mr. Bates on the caterpillar of a. + +Sphinx moth, musky odour of. + +Spiders, parental feeling in; +male, more active than female; +proportion of the sexes in; +secondary sexual characters of; +courtship of male; +attracted by music; +male, small size of. + +Spilosoma menthastri, rejected by turkeys. + +Spine, alteration of, to suit the erect attitude of man. + +Spirits, fondness of monkeys for. + +Spiritual agencies, belief in, almost universal. + +Spiza cyanea and ciris. + +Spoonbill, Chinese, change of plumage in. + +Spots, retained throughout groups of birds; +disappearance of, in adult mammals. + +Sprengel, C.K., on the sexuality of plants. + +Springboc, horns of the. + +Sproat, Mr., on the extinction of savages in Vancouver Island; +on the eradication of facial hair by the natives of Vancouver Island; +on the eradication of the beard by the Indians of Vancouver Island. + +Spurs, occurrence of, in female fowls; +development of, in various species of Phasianidae; +of Gallinaceous birds; +development of, in female Gallinaceae. + +Squilla, different colours of the sexes of a species of. + +Squirrels, battles of male; +African, sexual differences in the colouring of; +black. + +Stag, long hairs of the throat of; +horns of the; +battles of; +horns of the, with numerous branches; +bellowing of the; +crest of the. + +Stag-beetle, numerical proportion of sexes of; +use of jaws; +large size of male; +weapons of the male. + +Stainton, H.T., on the numerical proportion of the sexes in the smaller +moths; +habits of Elachista rufocinerea; +on the coloration of moths; +on the rejection of Spilosoma menthastri by turkeys; +on the sexes of Agrotis exclamationis. + +Staley, Bishop, mortality of infant Maories. + +Stallion, mane of the. + +Stallions, two, attacking a third; +fighting; +small canine teeth of. + +Stansbury, Captain, observations on pelicans. + +Staphylinidae, hornlike processes in male. + +Starfishes, parental feeling in; +bright colours of some. + +Stark, Dr., on the death-rate in towns and rural districts; +on the influence of marriage on mortality; +on the higher mortality of males in Scotland. + +Starling, American field-, pugnacity of male. + +Starling, red-winged, selection of a mate by the female. + +Starlings, three, frequenting the same nest; +new mates found by. + +Statues, Greek, Egyptian, Assyrian, etc., contrasted. + +Stature, dependence of, upon local influences. + +Staudinger, Dr., on breeding Lepidoptera; +his list of Lepidoptera. + +Staunton, Sir G., hatred of indecency a modern virtue. + +Stealing of bright objects by birds. + +Stebbing, T.R., on the nakedness of the human body. + +Stemmatopus. + +Stendhal, see Bombet. + +Stenobothrus pratorum, stridulation. + +Stephen, Mr. L., on the difference in the minds of men and animals; +on general concepts in animals; +distinction between material and formal morality. + +Sterility, general, of sole daughters; +when crossed, a distinctive character of species; +under changed conditions. + +Sterna, seasonal change of plumage in. + +Stickleback, polygamous; +male, courtship of the; +male, brilliant colouring of, during the breeding season; +nidification of the. + +Sticks used as implements and weapons by monkeys. + +Sting in bees. + +Stokes, Captain, on the habits of the great bower-bird. + +Stoliczka, Dr., on colours in snakes. + +Stoliczka, on the pre-anal pores of lizards. + +Stonechat, young of the. + +Stone implements, difficulty of making; +as traces of extinct tribes. + +Stones, used by monkeys for breaking hard fruits and as missiles; +piles of. + +Stork, black, sexual differences in the bronchi of the; +red beak of the. + +Storks, sexual difference in the colour of the eyes of. + +Strange, Mr., on the satin bowerbird. + +Strepsiceros kudu, horns of; +markings of. + +Stretch, Mr., on the numerical proportion in the sexes of chickens. + +Stridulation, by males of Theridion; +of Hemiptera; +of the Orthoptera and Homoptera discussed; +of beetles. + +Stripes, retained throughout groups of birds; +disappearance of, in adult mammals. + +Strix flammea. + +Structure, existence of unserviceable modifications of. + +Struggle for existence, in man. + +Struthers, Dr., on the occurrence of the supra-condyloid foramen in the +humerus of man. + +Sturnella ludoviciana, pugnacity of the male. + +Sturnus vulgaris. + +Sub-species. + +Suffering, in strangers, indifference of savages to. + +Suicide, formerly not regarded as a crime; +rarely practised among the lowest savages. + +Suidae, stripes of the young. + +Sulivan, Sir B.J., on speaking of parrots; +on two stallions attacking a third. + +Sumatra, compression of the nose by the Malays of. + +Sumner, Archb., man alone capable of progressive improvement. + +Sun-birds, nidification of. + +Superciliary ridge in man. + +Supernumerary digits, more frequent in men than in women; +inheritance of; +early development of. + +Superstitions, prevalence of. + +Superstitious customs. + +Supra-condyloid foramen in the early progenitors of man. + +Suspicion, prevalence of, among animals. + +Swallow-tail butterfly. + +Swallows deserting their young. + +Swan, black, wild, trachea of the; +white, young of; +red beak of the; +black-necked. + +Swans, young. + +Swaysland, Mr., on the arrival of migratory birds. + +Swifts, migration of. + +Swinhoe, R., on the common rat in Formosa and China; +behaviour of lizards when caught; +on the sounds produced by the male hoopoe; +on Dicrurus macrocercus and the spoonbill; +on the young of Ardeola; +on the habits of Turnix; +on the habits of Rhynchaea bengalensis; +on Orioles breeding in immature plumage. + +Sylvia atricapilla, young of. + +Sylvia cinerea, aerial love-dance of the male. + +Sympathy, among animals; +its supposed basis. + +Sympathies, gradual widening of. + +Syngnathous fishes, abdominal pouch in male. + +Sypheotides auritus, acuminated primaries of the male; +ear-tufts of. + +Tabanidae, habits of. + +Tadorna variegata, sexes and young of. + +Tadorna vulpanser. + +Tahitians, compression of the nose by the. + +Tail, rudimentary, occurrence of, in man; +convoluted body in the extremity of the; +absence of, in man and the higher apes; +variability of, in species of Macacus and in baboons; +presence of, in the early progenitors of man; +length of, in pheasants; +difference of length of the, in the two sexes of birds. + +Tait, Lawson, on the effects of natural selection on civilised nations. + +Tanager, scarlet, variation in the male. + +Tanagra aestiva, age of mature plumage in. + +Tanagra rubra, young of. + +Tanais, absence of mouth in the males of some species of; +relations of the sexes in; +dimorphic males of a species of. + +Tankerville, Earl, on the battles of wild bulls. + +Tanysiptera, races of, determined from adult males. + +Tanysiptera sylvia, long tail-feathers of. + +Taphroderes distortus, enlarged left mandible of the male. + +Tapirs, longitudinal stripes of young. + +Tarsi, dilatation of front, in male beetles. + +Tarsius. + +Tasmania, half-castes killed by the natives of. + +Tasmanians, extinction of. + +Taste, in the Quadrumana. + +Tattooing, universality of. + +Taylor, G., on Quiscalus major. + +Taylor, Rev. R., on tattooing in New Zealand. + +Tea, fondness of monkeys for. + +Teal, constancy of. + +Tear-sacs, of Ruminants. + +Teebay, Mr., on changes of plumage in spangled Hamburg fowls. + +Teeth, rudimentary incisor, in Ruminants; +posterior molar, in man; +wisdom; +diversity of; +canine, in the early progenitors of man; +canine, of male mammals; +in man, reduced by correlation; +staining of the; +front, knocked out or filed by some savages. + +Tegetmeier, Mr., on the transmission of colours in pigeons by one sex +alone; +numerical proportion of male and female births in dogs; +on the abundance of male pigeons; +on the wattles of game-cocks; +on the courtship of fowls; +on the loves of pigeons; +on dyed pigeons; +blue dragon pigeons. + +Tembeta, S. American ornament. + +Temper, in dogs and horses, inherited. + +Tench, proportions of the sexes in the; +brightness of male, during breeding season. + +Tenebrionidae, stridulation of. + +Tennent, Sir J.E., on the tusks of the Ceylon Elephant; +on the frequent absence of beard in the natives of Ceylon; +on the Chinese opinion of the aspect of the Cingalese. + +Tennyson, A., on the control of thought. + +Tenthredinidae, proportions of the sexes in; +fighting habits of male; +difference of the sexes in. + +Tephrodornis, young of. + +Terai, in India. + +Termites, habits of. + +Terns, white; +and black. + +Terns, seasonal change of plumage in. + +Terror, common action of, upon the lower animals and man. + +Testudo elegans. + +Testudo nigra. + +Tetrao cupido, battles of; +sexual difference in the vocal organs of. + +Tetrao phasianellus, dances of; +duration of dances of. + +Tetrao scoticus. + +Tetrao tetrix, pugnacity of the male. + +Tetrao umbellus, pairing of; +battles of; +drumming of the male. + +Tetrao urogalloides, dances of. + +Tetrao urogallus, pugnacity of the male. + +Tetrao urophasianus, inflation of the oesophagus in the male. + +Thamnobia, young of. + +Thecla, sexual differences of colouring in species of. + +Thecla rubi, protective colouring of. + +Thecophora fovea. + +Theognis, selection in mankind. + +Theridion, stridulation of males of. + +Theridion lineatum. + +Thomisus citreus, and Thomisus floricolens, difference of colour in the +sexes of. + +Thompson, J.H., on the battles of sperm-whales. + +Thompson, W., on the colouring of the male char during the breeding season; +on the pugnacity of the males of Gallinula chloropus; +on the finding of new mates by magpies; +on the finding of new mates by Peregrine falcons. + +Thorax, processes of, in male beetles. + +Thorell, T., on the proportion of sexes in spiders. + +Thornback, difference in the teeth of the two sexes of the. + +Thoughts, control of. + +Thrush, pairing with a blackbird; +colours and nidification of the. + +Thrushes, characters of young. + +Thug, remorse of a. + +Thumb, absence of, in Ateles and Hylobates. + +Thury, M., on the numerical proportion of male and female births among the +Jews. + +Thylacinus, possession of the marsupial sac by the male. + +Thysanura. + +Tibia, dilated, of the male Crabro cribrarius. + +Tibia and femur, proportions of, in the Aymara Indians. + +Tierra del Fuego, marriage-customs of. + +Tiger, colours and markings of the. + +Tigers, depopulation of districts by, in India. + +Tillus elongatus, difference of colour in the sexes of. + +Timidity, variability of, in the same species. + +Tinca vulgaris. + +Tipula, pugnacity of male. + +Tits, sexual difference of colour in. + +Toads, male, treatment of ova by some; +male, ready to breed before the female. + +Todas, infanticide and proportion of sexes; +practice polyandry; +choice of husbands amongst. + +Toe, great, condition of, in the human embryo. + +Tomicus villosus, proportion of the sexes in. + +Tomtit, blue, sexual difference of colour in the. + +Tonga Islands, beardlessness of the natives of. + +Tooke, Horne, on language. + +Tools, flint; +used by monkeys; +use of. + +Topknots in birds. + +Tortoise, voice of the male. + +Tortures, submitted to by American savages. + +Totanus, double moult in. + +Toucans, colours and nidification of the; +beaks and ceres of the. + +Towns, residence in, a cause of diminished stature. + +Toynbee, J., on the external shell of the ear in man. + +Trachea, convoluted and imbedded in the sternum, in some birds; +structure of the, in Rhynchaea. + +Trades, affecting the form of the skull. + +Tragelaphus, sexual differences of colour in. + +Tragelaphus scriptus, dorsal crest of; +markings of. + +Tragopan, swelling of the wattles of the male, during courtship; +display of plumage by the male; +marking of the sexes of the. + +Tragops dispar, sexual difference in the colour of. + +Training, effect of, on the mental difference between the sexes of man. + +Transfer of male characters to female birds. + +Transmission, equal, of ornamental characters, to both sexes in mammals. + +Traps, avoidance of, by animals; +use of. + +Treachery, to comrades, avoidance of, by savages. + +Tremex columbae. + +Tribes, extinct; +extinction of. + +Trichius, difference of colour in the sexes of a species of. + +Trigla. + +Trigonocephalus, noise made by tail of. + +Trimen, R., on the proportion of the sexes in South African butterflies; +on the attraction of males by the female Lasiocampa quercus; +on Pneumora; +on difference of colour in the sexes of beetles; +on moths brilliantly coloured beneath; +on mimicry in butterflies; +on Gynanisa Isis, and on the ocellated spots of Lepidoptera; +on Cyllo Leda. + +Tringa, sexes and young of. + +Tringa cornuta. + +Triphaena, coloration of the species of. + +Tristram, H.B., on unhealthy districts in North Africa; +on the habits of the chaffinch in Palestine; +on the birds of the Sahara; +on the animals inhabiting the Sahara. + +Triton cristatus. + +Triton palmipes. + +Triton punctatus. + +Troglodyte skulls, greater than those of modern Frenchmen. + +Troglodytes vulgaris. + +Trogons, colours and nidification of the. + +Tropic-birds, white only when mature. + +Tropics, freshwater fishes of the. + +Trout, proportion of the sexes in; +male, pugnacity of the. + +Trox sabulosus, stridulation of. + +Truth, not rare between members of the same tribe; +more highly appreciated by certain tribes. + +Tulloch, Major, on the immunity of the negro from certain fevers. + +Tumbler, almond, change of plumage in the. + +Turdus merula, young of. + +Turdus migratorius. + +Turdus musicus. + +Turdus polyglottus, young of. + +Turdus torquatus. + +Turkey, wild, pugnacity of young male; +wild, notes of the; +swelling of the wattles of the male; +variety of, with a top-knot; +recognition of a dog by a; +male, wild, acceptable to domesticated females; +wild, first advances made by older females; +wild, breast-tuft of bristles of the. + +Turkey-cock, scraping of the wings of, upon the ground; +wild, display of plumage by; +fighting habits of. + +Turner, Prof. W., on muscular fasciculi in man referable to the panniculus +carnosus; +on the occurrence of the supra-condyloid foramen in the human humerus; +on muscles attached to the coccyx in man; +on the filum terminale in man; +on the variability of the muscles; +on abnormal conditions of the human uterus; +on the development of the mammary glands; +on male fishes hatching ova in their mouths; +on the external perpendicular fissure of the brain; +on the bridging convolutions in the brain of a chimpanzee. + +Turnix, sexes of some species of. + +Turtle-dove, cooing of the. + +Tuttle, H., on the number of species of man. + +Tylor, E.B., on emotional cries, gestures, etc., of man; +on the origin of the belief in spiritual agencies; +remorse for violation of tribal usage in marrying; +on the primitive barbarism of civilised nations; +on the origin of counting; +inventions of savages; +on resemblances, of the mental characters in different races of man. + +Type of structure, prevalence of. + +Typhaeus, stridulating organs of; +stridulation of. + +Twins, tendency to produce, hereditary. + +Twite, proportion of the sexes in. + +Ugliness, said to consist in an approach to the lower animals. + +Umbrella-bird. + +Umbrina, sounds produced by. + +United States, rate of increase in; +influence of natural selection on the progress of; +change undergone by Europeans in the. + +Upupa epops, sounds produced by the male. + +Uraniidae, coloration of the. + +Uria troile, variety of (=U. lacrymans). + +Urodela. + +Urosticte Benjamini, sexual differences in. + +Use and disuse of parts, effects of; +influence of, on the races of man. + +Uterus, reversion in the; +more or less divided, in the human subject; +double, in the early progenitors of man. + +Vaccination, influence of. + +Vancouver Island, Mr. Sproat on the savages of; +natives of, eradication of facial hair by the. + +Vanellus cristatus, wing tubercles of the male. + +Vanessae, resemblance of lower surface of, to bark of trees. + +Variability, causes of; +in man, analogous to that in the lower animals; +of the races of man; +greater in men than in women; +period of, relation of the, to sexual selection; +of birds; +of secondary sexual characters in man. + +Variation, laws of; +correlated; +in man; +analogous; +analogous, in plumage of birds. + +Variations, spontaneous. + +Varieties, absence of, between two species, evidence of their distinctness. + +Variety, an object in nature. + +Variola, communicable between man and the lower animals. + +Vaureal, human bones from. + +Veddahs, monogamous habits of. + +Veitch, Mr., on the aversion of Japanese ladies to whiskers. + +Vengeance, instinct of. + +Venus Erycina, priestesses of. + +Vermes. + +Vermiform appendage. + +Verreaux, M., on the attraction of numerous males by the female of an +Australian Bombyx. + +Vertebrae, caudal, number of in macaques and baboons; +of monkeys, partly imbedded in the body. + +Vertebrata, common origin of the; +most ancient progenitors of; +origin of the voice in air-breathing. + +Vesicula prostatica, the homologue of the uterus. + +Vibrissae, represented by long hairs in the eyebrows. + +Vidua. + +Vidua axillaris. + +Villerme, M., on the influence of plenty upon stature. + +Vinson, Aug., courtship of male spider; +on the male of Epeira nigra. + +Viper, difference of the sexes in the. + +Virey, on the number of species of man. + +Virtues, originally social only; +gradual appreciation of. + +Viscera, variability of, in man. + +Vlacovich, Prof., on the ischio-pubic muscle. + +Vocal music of birds. + +Vocal organs of man; +of birds; +of frogs; +of the Insessores; +difference of, in the sexes of birds; +primarily used in relation to the propagation of the species. + +Vogt, Karl, on the origin of species; +on the origin of man; +on the semilunar fold in man; +on microcephalous idiots; +on the imitative faculties of microcephalous idiots; +on skulls from Brazilian caves; +on the evolution of the races of man; +on the formation of the skull in women; +on the Ainos and negroes; +on the increased cranial difference of the sexes in man with race +development; +on the obliquity of the eye in the Chinese and Japanese. + +Voice in mammals; +in monkeys and man; +in man; +origin of, in air-breathing vertebrates. + +Von Baer, see Baer. + +Vulpian, Prof., on the resemblance between the brains of man and the higher +apes. + +Vultures, selection of a mate by the female; +colours of. + +Waders, young of. + +Wagner, R., on the occurrence of the diastema in a Kaffir skull; +on the bronchi of the black stork. + +Wagtail, Ray's, arrival of the male before the female. + +Wagtails, Indian, young of. + +Waist, proportions of, in soldiers and sailors. + +Waitz, Prof., on the number of species of man; +on the liability of negroes to tropical fevers after residence in a cold +climate; +on the colour of Australian infants; +on the beardlessness of negroes; +on the fondness of mankind for ornaments; +on negro ideas of female beauty; +on Javan and Cochin Chinese ideas of beauty. + +Waldeyer, M., on the hermaphroditism of the vertebrate embryo. + +Wales, North, numerical proportion of male and female births in. + +Walkenaer and Gervais, spider attracted by music; +on the Myriapoda. + +Walker, Alex., on the large size of the hands of labourers' children. + +Walker, F., on sexual differences in the diptera. + +Wallace, Dr. A., on the prehensile use of the tarsi in male moths; +on the rearing of the Ailanthus silkmoth; +on breeding Lepidoptera; +proportion of sexes of Bombyx cynthia, B. yamamai, and B. Pernyi reared by; +on the development of Bombyx cynthia and B. yamamai; +on the pairing of Bombyx cynthia. + +Wallace, A.R., on the origin of man; +on the power of imitation in man; +on the use of missiles by the orang; +on the varying appreciation of truth among different tribes; +on the limits of natural selection in man; +on the occurrence of remorse among savages; +on the effects of natural selection on civilised nations; +on the use of the convergence of the hair at the elbow in the orang; +on the contrast in the characters of the Malays and Papuans; +on the line of separation between the Papuans and Malays; +on the birds of paradise; +on the sexes of Ornithoptera Croesus; +on protective resemblances; +on the relative sizes of the sexes of insects; +on Elaphomyia; +on the pugnacity of the males of Leptorhynchus angustatus; +on sounds produced by Euchirus longimanus; +on the colours of Diadema; +on Kallima; +on the protective colouring of moths; +on bright coloration as protective in butterflies; +on variability in the Papilionidae; +on male and female butterflies, inhabiting different stations; +on the protective nature of the dull colouring of female butterflies; +on mimicry in butterflies; +on the bright colours of caterpillars; +on brightly-coloured fishes frequenting reefs; +on the coral snakes; +on Paradisea apoda; +on the display of plumage by male birds of paradise; +on assemblies of birds of paradise; +on the instability of the ocellated spots in Hipparchia Janira; +on sexually limited inheritance; +on the sexual coloration of birds; +on the relation between the colours and nidification of birds; +on the coloration of the Cotingidae; +on the females of Paradisea apoda and papuana; +on the incubation of the cassowary; +on protective coloration in birds; +on the Babirusa; +on the markings of the tiger; +on the beards of the Papuans; +on the hair of the Papuans; +on the distribution of hair on the human body. + +Walrus, development of the nictitating membrane in the; +tusks of the; +use of the tusks by the. + +Walsh, B.D., on the proportion of the sexes in Papilio Turnus; +on the Cynipidae and Cecidomyidae; +on the jaws of Ammophila; +on Corydalis cornutus; +on the prehensile organs of male insects; +on the antennae of Penthe; +on the caudal appendages of dragonflies; +on Platyphyllum concavum; +on the sexes of the Ephemeridae; +on the difference of colour in the sexes of Spectrum femoratum; +on sexes of dragon-flies; +on the difference of the sexes in the Ichneumonidae; +on the sexes of Orsodacna atra; +on the variation of the horns of the male Phanaeas carnifex; +on the coloration of the species of Anthocharis. + +Wapiti, battles of; +traces of horns in the female; +attacking a man; +crest of the male; +sexual difference in the colour of the. + +Warbler, hedge-; +young of the. + +Warblers, superb, nidification of. + +Wariness, acquired by animals. + +Warington, R., on the habits of the stickleback; +on the brilliant colours of the male stickleback during the breeding +season. + +Wart-hog, tusks and pads of the. + +Watchmakers, short-sighted. + +Waterhen. + +Waterhouse, C.O., on blind beetles; +on difference of colour in the sexes of beetles. + +Waterhouse, G.R., on the voice of Hylobates agilis. + +Water-ouzel, autumn song of the. + +Waterton, C., on the Bell-bird; +on the pairing of a Canada goose with a Bernicle gander; +on hares fighting. + +Wattles, disadvantageous to male birds in fighting. + +Weale, J., Mansel, on a South African caterpillar. + +Wealth, influence of. + +Weapons, used by man; +employed by monkeys; +offensive, of males; +of mammals. + +Weaver-bird. + +Weaver-birds, rattling of the wings of; +assemblies of. + +Webb, Dr., on the wisdom teeth. + +Wedderburn, Mr., assembly of black game. + +Wedgwood, Hensleigh, on the origin of language. + +Weevils, sexual difference in length of snout in some. + +Weir, Harrison, on the numerical proportion of the sexes in pigs and +rabbits; +on the sexes of young pigeons; +on the songs of birds; +on pigeons; +on the dislike of blue pigeons to other coloured varieties; +on the desertion of their mates by female pigeons. + +Weir, J. Jenner, on the nightingale and blackcap; +on the relative sexual maturity of male birds; +on female pigeons deserting a feeble mate; +on three starlings frequenting the same nest; +on the proportion of the sexes in Machetes pugnax and other birds; +on the coloration of the Triphaenae; +on the rejection of certain caterpillars by birds; +on sexual differences of the beak in the goldfinch; +on a piping bullfinch; +on the object of the nightingale's song; +on song-birds; +on the pugnacity of male fine-plumaged birds; +on the courtship of birds; +on the finding of new mates by Peregrine falcons and Kestrels; +on the bullfinch and starling; +on the cause of birds remaining unpaired; +on starlings and parrots living in triplets; +on recognition of colour by birds; +on hybrid birds; +on the selection of a greenfinch by a female canary; +on a case of rivalry of female bullfinches; +on the maturity of the golden pheasant. + +Weisbach, Dr., measurement of men of different races; +on the greater variability of men than of women; +on the relative proportions of the body in the sexes of different races of +man. + +Weismann, Prof., colours of Lycaenae. + +Welcker, M., on brachycephaly and dolichocephaly; +on sexual differences in the skull in man. + +Wells, Dr., on the immunity of coloured races from certain poisons. + +Westring, on the stridulation of males of Theridion; +on the stridulation of Reduvius personatus; +on the stridulation of beetles; +on the stridulation of Omaloplia brunnea; +on the stridulating organs of the Coleoptera; +on sounds produced by Cychrus. + +Westropp, H.M., on reason in a bear; +on the prevalence of certain forms of ornamentation. + +Westwood, J.O., on the classification of the Hymenoptera; +on the Culicidae and Tabanidae; +on a Hymenopterous parasite with a sedentary male; +on the proportions of the sexes in Lucanus cervus and Siagonium; +on the absence of ocelli in female Mutillidae; +on the jaws of Ammophila; +on the copulation of insects of distinct species; +on the male of Crabro cribrarius; +on the pugnacity of the male Tipulae; +on the stridulation of Pirates stridulus; +on the Cicadae; +on the stridulating organs of the cricket; +on Ephippiger vitium; +on Pneumora; +on the pugnacity of the Mantides; +on Platyblemnus; +on difference in the sexes of the Agrionidae; +on the pugnacity of the males of a species of Tenthredinae; +on the pugnacity of the male stag-beetle; +on Bledius taurus and Siagonium; +on lamellicorn beetles; +on the coloration of Lithosia. + +Whale, Sperm-, battles of male. + +Whales, nakedness of. + +Whately, Arch., language not peculiar to man; +on the primitive civilisation of man. + +Whewell, Prof., on maternal affection. + +Whiskers, in monkeys. + +White, F.B., noise produced by Hylophila. + +White, Gilbert, on the proportion of the sexes in the partridge; +on the house-cricket; +on the object of the song of birds; +on the finding of new mates by white owls; +on spring coveys of male partridges. + +Whiteness, a sexual ornament in some birds; +of mammals inhabiting snowy countries. + +White-throat, aerial love-dance of the male. + +Whitney, Prof., on the development of language; +language not indispensable for thought. + +Widgeon, pairing with a pintail duck. + +Widow-bird, polygamous; +breeding plumage of the male; +female, rejecting the unadorned male. + +Widows and widowers, mortality of. + +Wilckens, Dr., on the modification of domestic animals in mountainous +regions; +on a numerical relation between the hairs and excretory pores in sheep. + +Wilder, Dr. Burt, on the greater frequency of supernumerary digits in men +than in women. + +Williams, on the marriage-customs of the Fijians. + +Wilson, Dr., on the conical heads of the natives of North-Western Africa; +on the Fijians; +on the persistence of the fashion of compressing the skull. + +Wing-spurs. + +Wings, differences of, in the two sexes of butterflies and Hymenoptera; +play of, in the courtship of birds. + +Winter, change of colour of mammals in. + +Witchcraft. + +Wives, traces of the forcible capture of. + +Wolf, winter change of the. + +Wolff, on the variability of the viscera in man. + +Wollaston, T.V., on Eurygnathus; +on musical Curculionidae; +on the stridulation of Acalles. + +Wolves, learning to bark from dogs; +hunting in packs. + +Wolves, black. + +Wombat, black varieties of the. + +Women, distinguished from men by male monkeys; +preponderance of, in numbers; +selection of, for beauty; +effects of selection of, in accordance with different standards of beauty; +practice of capturing; +early betrothals and slavery of; +freedom of selection by, in savage tribes. + +Wonder, manifestations of, by animals. + +Wonfor, Mr., on sexual peculiarities, in the wings of butterflies. + +Wood, J., on muscular variations in man; +on the greater variability of the muscles in men than in women. + +Wood, T.W., on the colouring of the orange-tip butterfly; +on the habits of the Saturniidae; +quarrels of chamaeleons; +on the habits of Menura Alberti; +on Tetrao cupido; +on the display of plumage by male pheasants; +on the ocellated spots of the Argus pheasant; +on fighting of Menura superba; +on the habits of the female cassowary. + +Woodcock, coloration of the. + +Woodpecker, selection of a mate by the female. + +Woodpeckers, tapping of; +colours and nidification of the; +characters of young. + +Woolner, Mr., observations on the ear in man. + +Wormald, Mr., on the coloration of Hypopyra. + +Wounds, healing of. + +Wren, young of the. + +Wright, C.A., on the young of Orocetes and Petrocincla. + +Wright, Chauncey, great brain-power requisite for language; +on correlative acquisition; +on the enlargement of the brain in man. + +Wright, Mr., on the Scotch deer-hound; +on sexual preference in dogs; +on the rejection of a horse by a mare. + +Wright, W. von, on the protective plumage of the Ptarmigan. + +Writing. + +Wyman, Prof., on the prolongation of the coccyx in the human embryo; +on the condition of the great toe in the human embryo; +on the occurrence of the supra-condyloid foramen in the humerus of man; +on variation in the skulls of the natives of the Sandwich Islands; +on the hatching of the eggs in the mouths and branchial cavities of male +fishes. + +Xenarchus, on the Cicadae. + +Xenophon, selection in mankind advocated by. + +Xenorhynchus, sexual difference in the colour of the eyes in. + +Xiphophorus Hellerii, peculiar anal fin of the male. + +Xylocopa, difference of the sexes in. + +Yarrel, W., on the habits of the Cyprinidae; +on Raia clavata; +on the characters of the male salmon during the breeding season; +on the characters of the rays; +on the gemmeous dragonet; +on colours of salmon; +on the spawning of the salmon; +on the incubation of the Lophobranchii; +on rivalry in song-birds; +on the trachea of the swan; +on the moulting of the Anatidae; +on the young of the waders. + +Yellow fever, immunity of negroes and mulattoes from. + +Youatt, Mr., on the development of the horns in cattle. + +Yura-caras, their notions of beauty. + +Zebra, rejection of an ass by a female; +stripes of the. + +Zebus, humps of. + +Zigzags, prevalence of, as ornaments. + +Zincke, Mr., on European emigration to America. + +Zootoca vivipara, sexual difference in the colour of. + +Zouteveen, Dr., polydactylism; +proportion of sexes at Cape of Good Hope; +spiders attracted by music; +on sounds produced by fish. + +Zygaenidae, coloration of the. + + +THE END. + + + + + +End of this Project Gutenberg Etext of The Descent of Man by Charles Darwin + |