The Descent of Man | Page 4

this opportunity of remarking that my critics frequently assume that I attribute all changes of corporeal structure and mental power exclusively to the natural selection of such variations as are often called spontaneous; whereas, even in the first edition of the 'Origin of Species,' I distinctly stated that great weight must be attributed to the inherited effects of use and disuse, with respect both to the body and mind. I also attributed some amount of modification to the direct and prolonged action of changed conditions of life. Some allowance, too, must be made for occasional reversions of structure; nor must we forget what I have called "correlated" growth, meaning, thereby, that various parts of the organisation are in some unknown manner so connected, that when one part varies, so do others; and if variations in the one are accumulated by selection, other parts will be modified. Again, it has been said by several critics, that when I found that many details of structure in man could not be explained through natural selection, I invented sexual selection; I gave, however, a tolerably clear sketch of this principle in the first edition of the 'Origin of Species,' and I there stated that it was applicable to man. This subject of sexual selection has been treated at full length in the present work, simply because an opportunity was here first afforded me. I have been struck with the likeness of many of the half-favourable criticisms on sexual selection, with those which appeared at first on natural selection; such as, that it would explain some few details, but certainly was not applicable to the extent to which I have employed it. My conviction of the power of sexual selection remains unshaken; but it is probable, or almost certain, that several of my conclusions will hereafter be found erroneous; this can hardly fail to be the case in the first treatment of a subject. When naturalists have become familiar with the idea of sexual selection, it will, as I believe, be much more largely accepted; and it has already been fully and favourably received by several capable judges.
DOWN, BECKENHAM, KENT, September, 1874.
First Edition February 24, 1871. Second Edition September, 1874.
CONTENTS.
INTRODUCTION.


PART I. THE DESCENT OR ORIGIN OF MAN.


CHAPTER I.
The Evidence of the Descent of Man from some Lower Form.
Nature of the evidence bearing on the origin of man--Homologous structures in man and the lower animals--Miscellaneous points of correspondence-- Development--Rudimentary structures, muscles, sense-organs, hair, bones, reproductive organs, etc.--The bearing of these three great classes of facts on the origin of man.

CHAPTER II.
On the Manner of Development of Man from some Lower Form.
Variability of body and mind in man--Inheritance--Causes of variability-- Laws of variation the same in man as in the lower animals--Direct action of the conditions of life--Effects of the increased use and disuse of parts-- Arrested development--Reversion--Correlated variation--Rate of increase-- Checks to increase--Natural selection--Man the most dominant animal in the world--Importance of his corporeal structure--The causes which have led to his becoming erect--Consequent changes of structure--Decrease in size of the canine teeth--Increased size and altered shape of the skull--Nakedness --Absence of a tail--Defenceless condition of man.

CHAPTER III.
Comparison of the Mental Powers of Man and the Lower Animals.
The difference in mental power between the highest ape and the lowest savage, immense--Certain instincts in common--The emotions--Curiosity-- Imitation--Attention--Memory--Imagination--Reason--Progressive improvement --Tools and weapons used by animals--Abstraction, Self-consciousness-- Language--Sense of beauty--Belief in God, spiritual agencies, superstitions.

CHAPTER IV.
Comparison of the Mental Powers of Man and the Lower Animals--continued.
The moral sense--Fundamental proposition--The qualities of social animals-- Origin of sociability--Struggle between opposed instincts--Man a social animal--The more enduring social instincts conquer other less persistent instincts--The social virtues alone regarded by savages--The self-regarding virtues acquired at a later stage of development--The importance of the judgment of the members of the same community on conduct--Transmission of moral tendencies--Summary.

CHAPTER V.
On the Development of the Intellectual and Moral Faculties during Primeval and Civilised times.
Advancement of the intellectual powers through natural selection-- Importance of imitation--Social and moral faculties--Their development within the limits of the same tribe--Natural selection as affecting civilised nations--Evidence that civilised nations were once barbarous.

CHAPTER VI.
On the Affinities and Genealogy of Man.
Position of man in the animal series--The natural system genealogical-- Adaptive characters of slight value--Various small points of resemblance between man and the Quadrumana--Rank of man in the natural system-- Birthplace and antiquity of man--Absence of fossil connecting-links--Lower stages in the genealogy of man, as inferred firstly from his affinities and secondly from his structure--Early androgynous condition of the Vertebrata --Conclusion.

CHAPTER VII.
On the Races of Man.
The nature and value of specific characters--Application to the races of man--Arguments in favour of, and opposed to, ranking the so-called races of man as distinct species--Sub-species--Monogenists and polygenists-- Convergence of character--Numerous points of resemblance in body and mind between the most distinct races of man--The state of man when he