preliminary
labours for his immortal work, "The Origin of Species", Darwin expresses
himself very forcibly against the views of Lamarck, speaking of
Lamarckian "nonsense," ("Life and Letters", Vol. II. page 23.), and
of Lamarck's "absurd, though clever work" (Loc. cit. page 39.) and
expressly declaring, "I attribute very little to the direct action of
climate, etc." (Loc. cit. (1856), page 82.) yet in later life he became
more and more convinced of the influence of external conditions. In
1876, that is, two years after the appearance of the second edition of
"The Descent of Man", he writes with his usual candid honesty: "In my
opinion the greatest error which I have committed, has been not allowing
sufficient weight to the direct action of the environment, i.e. food,
climate, etc. independently of natural selection." (Ibid. Vol. III. page
159.) It is certain from this change of opinion that, if he had been
able to make up his mind to issue a third edition of "The Descent of
Man", he would have ascribed a much greater influence to the effect of
external conditions in explaining the different characters of the races
of man than he did in the second edition. He would also undoubtedly have
attributed less influence to sexual selection as a factor in the origin
of the different bodily characteristics, if indeed he would not have
excluded it altogether.

In Part III of the "Descent" two additional chapters are devoted to the
discussion of sexual selection in relation to man. These may be very
briefly referred to. Darwin here seeks to show that sexual selection has
been operative on man and his primitive progenitor. Space fails me to
follow out his interesting arguments. I can only mention that he is
inclined to trace back hairlessness, the development of the beard in
man, and the characteristic colour of the different human races to
sexual selection. Since bareness of the skin could be no advantage, but
rather a disadvantage, this character cannot have been brought about by
natural selection. Darwin also rejected a direct influence of climate as
a cause of the origin of the skin-colour. I have already expressed the
opinion, based on the development of his views as shown in his letters,
that in a third edition Darwin would probably have laid more stress on
the influence of external environment. He himself feels that there are
gaps in his proofs here, and says in self-criticism: "The views here
advanced, on the part which sexua