CONTENTS.: ON THE DESCENT OF MAN. by Charles Darwin CONTENTS. INTRODUCTION .. .. .. .. .. .. .. .. .. Page 1-5 PART I. ON THE DESCENT OF MAN. By Charles Darwin 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, &c. -- The bearing of these three great classes of facts on the origin of man .. .. .. .. .. .. .. .. .. .. .. 9-33 CHAPTER II. 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 -- Language -- Self-consciousness -- Sense of beauty -- Belief in God, spiritual agencies, superstitions 34-69 CHAPTER III. 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 [page] vi 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 .. .. Page 70-106 CHAPTER IV. 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 .. .. .. .. 107-157 CHAPTER V. ON THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL FACULTIES DURING PRIMEVAL AND CIVILISED TIMES. The 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.. .. .. .. .. .. 158-184 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 [page] vii 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 androgyngus condition of the Vertebrata--Conclusion .. .. .. .. Page 185-213. 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. 214-250. 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--On the limitation of the numbers of the two sexes through natural selection 253-320 [page] viii 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 .. .. .. .. .. .. Page 321-340 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 colours--Coleoptera, colours; furnished with great horns, apparently as an ornament; battles; stridulating organs generally common to both sexes.. .. .. .. .. 341-385 CHAPTER XI. INSECTS, continued.--ORDER LEPIDOPTERA. 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 -- Mimickry, 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 .. .. .. .. .. .. .. 386-423 [page 1] THE DESCENT OF MAN; AND ON 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 crèation indèpendante 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; VOL. I. B [page] 2 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 other men, 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, whether it be man or any other animal, to which our attention may be directed, remain to be considered; 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 [page] 3 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 discussed 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 single 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. La- B 2 [page] 4 marck 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, Büchner, Rolle, &c.,1 and especially by Häckel. This last naturalist, besides his great work, 'Generelle Morphologie' (1866), has recently (1868, with a second edit. 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. Häckel'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 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. Büchner; 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, p. 81) a very curious paper on rudimentary characters, as bearing on the origin of man. Another work has (1869) been published by Dr. Barrago Francesco, bearing in Italian the title of "Man, made in the image of God, was also made in the image of the ape." [page] 5 'Origin of Species' (first edition, p. 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 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, which is partially completed, for separate publication. 2 Prof. Häckel is the sole author who, since the publication of the 'Origin,' has discussed, in his various works, in a very able manner, the subject of sexual selection, and has seen its full importance. [page 6] [page 7]