The Descent of Man and Selection in Relation to Sex, Vol. I

CHAPTER II.. Comparison of the Mental Powers of Man and the Lower Animals.

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

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 and 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 70-106

CHAPTER IV.. On the Manner of Development of Man From Some Lower Form.

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

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.

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 185-213

CHAPTER VII.. On the Races of Man.

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

CHAPTER IX.. Secondary Sexual Characters in the Lower Classes of the Animal

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 321-340

CHAPTER X.. Secondary Sexual Characters of Insects.

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.

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

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 creation independante et de toutes pieces, des especes," 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 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 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. 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, Buechner, Rolle, &c., and especially by Haeckel. This last naturalist, besides his great work, 'Generelle Morphologie' (1866), has recently (1868, with a second edit. in 1870), published his 'Natuerliche Schoepfungsgeschichte,' 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.

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