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 Some new illustrations have been introduced, and four of the old drawings have been replaced by better ones, done from life by Mr.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. TABLE OF THE PRINCIPAL ADDITIONS AND CORRECTIONS TO THE PRESENT EDITION. Discussion on the rudimentary points in the human ear revised. Cases of men born with hairy bodies. Mantegazza on the last molar tooth in man. Bianconi on homologous structures, as explained Sense of humour in dogs. Further facts on imitation in man and animals. Acquisition of experience by animals. Power of forming concepts in relation to lan- Pleasure from certain sounds, colours, and forms. Fidelity in the elephant. Galton on gregariousness of cattle. Parental affection. Persistence of enmity and hatred. Nature and strength of shame, regret, and re morse. Suicide amongst savages. The motives of conduct. Selection, as applied to primeval man. Resemblances between idiots and animals. Supernumerary mammæ and digits. Further cases of muscles proper to animals appearing in man. Broca average capacity of skull diminished by the preservation of the inferior members of society. Note by Professor Huxley on the development of the brain in man and apes. Special organs of male parasitic worms for holding the female. Greater variability of male than female; direct action of the environment in causing differ-ences between the sexes. Period of development of protuberances on birds' heads determines their transmission to one or both sexes. Causes of excess of male births. Proportion of the sexes in the bee family. Excess of males perhaps sometimes determined Bright colours of lowly organised animals. Cause of smallness of male spiders. Use of phosphorescence of the glow-worm. Use of bright colours to Hemiptera (bugs). Development of stridulating apparatus in Or- Hermann Müller on sexual differences of bees. Display of beauty by butterflies. Female butterflies, taking the more active part in courtship, brighter than their males. Further cases of mimicry in butterflies and moths. Cause of bright and diversified colours of caterpillars. |