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diff --git a/2300-0.txt b/2300-0.txt new file mode 100644 index 0000000..7265f51 --- /dev/null +++ b/2300-0.txt @@ -0,0 +1,33333 @@ +The Project Gutenberg eBook of The Descent of Man, by Charles Darwin + +This eBook is for the use of anyone anywhere in the United States and +most other parts of the world at no cost and with almost no restrictions +whatsoever. You may copy it, give it away or re-use it under the terms +of the Project Gutenberg License included with this eBook or online at +www.gutenberg.org. If you are not located in the United States, you +will have to check the laws of the country where you are located before +using this eBook. + +Title: The Descent of Man + +Author: Charles Darwin + +Release Date: November 28, 1999 [eBook #2300] +[Most recently updated: December 27, 2021] + +Language: English + +Character set encoding: UTF-8 + +Produced by: Sue Asscher and David Widger + +*** START OF THE PROJECT GUTENBERG EBOOK THE DESCENT OF MAN *** + + + + +THE DESCENT OF MAN AND SELECTION IN RELATION TO SEX + +By Charles Darwin + + +CONTENTS + + PREFACE TO THE SECOND EDITION. + DETAILED TABLE OF CONTENTS + THE DESCENT OF MAN; AND SELECTION IN RELATION TO SEX. + INTRODUCTION. + + PART I. THE DESCENT OR ORIGIN OF MAN. + CHAPTER I. THE EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM. + CHAPTER II. — ON THE MANNER OF DEVELOPMENT OF MAN FROM SOME LOWER FORM. + CHAPTER III. — COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS. + CHAPTER IV. — COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS, continued. + CHAPTER V. — ON THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL FACULTIES DURING PRIMEVAL AND CIVILISED TIMES. + CHAPTER VI. — ON THE AFFINITIES AND GENEALOGY OF MAN. + CHAPTER VII. — ON THE RACES OF MAN. + + PART II. SEXUAL SELECTION. + CHAPTER VIII. — PRINCIPLES OF SEXUAL SELECTION. + CHAPTER IX. — SECONDARY SEXUAL CHARACTERS IN THE LOWER CLASSES OF THE ANIMAL KINGDOM. + CHAPTER X. — SECONDARY SEXUAL CHARACTERS OF INSECTS. + CHAPTER XI. — INSECTS, continued. ORDER LEPIDOPTERA. (BUTTERFLIES AND MOTHS.) + CHAPTER XII. — SECONDARY SEXUAL CHARACTERS OF FISHES, AMPHIBIANS, AND REPTILES. + CHAPTER XIII. — SECONDARY SEXUAL CHARACTERS OF BIRDS. + CHAPTER XIV. — BIRDS—continued. + CHAPTER XV. — BIRDS—continued. + CHAPTER XVI. — BIRDS—concluded. + CHAPTER XVII. — SECONDARY SEXUAL CHARACTERS OF MAMMALS. + CHAPTER XVIII. — SECONDARY SEXUAL CHARACTERS OF MAMMALS, continued. + + PART III. — SEXUAL SELECTION IN RELATION TO MAN, AND CONCLUSION. + CHAPTER XIX. — SECONDARY SEXUAL CHARACTERS OF MAN. + CHAPTER XX. — SECONDARY SEXUAL CHARACTERS OF MAN, continued. + CHAPTER XXI. — GENERAL A SUMMARY AND CONCLUSION. + + + + +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. + + + + +DETAILED TABLE OF 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 A 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. + + + + +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 inhabiting 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 A 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 Schöpfungsgeschichte,’ 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 vertebrae, 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 +be 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 on 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 was 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. + +A 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 +Schöpfungsgeschichte,’ 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 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. + +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 Arctic 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 Fuegians 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 with 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 Arctic 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. + +A 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 in 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. + +A 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’étalage de leurs vives +couleurs chercher a attirer l’attention des femelles, lesquelles ne +paraissaient indifférentes a ce manège, 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 submaxillary 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 submaxillary 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 amorous 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. Americana: 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 head; 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.’) 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 hand, 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 A 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 has 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 they 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 a 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 possibly 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. + +A 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 heads 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 Aethiopian 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, ‘Säugethiere,’ 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. + +A 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 he 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. + +A 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 A 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-happiness 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 aegyptiacus, 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. + +Hymenoptera, 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 Coleoptera; 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 THE PROJECT GUTENBERG EBOOK THE DESCENT OF MAN *** + +Updated editions will replace the previous one--the old editions will +be renamed. + +Creating the works from print editions not protected by U.S. copyright +law means that no one owns a United States copyright in these works, +so the Foundation (and you!) can copy and distribute it in the +United States without permission and without paying copyright +royalties. 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