Charles Darwin 21
that left no doubt about our continuity with the apes. Charles Lyell also had
things to say inThe Antiquity of Man[1863]. Probably, Darwin would have been
happy to let sleeping dogs lie. But it was not to be. It was Alfred Russel Wallace
of all people who stirred the pot. As a young man, he seems to have had no
more religious belief than anyone. In the 1840s, he was able to readVestigesand
at once convert to evolutionism. After theOriginwas published, and Wallace
had returned to England, at first it was he who pushed an evolutionary selection-
inspired treatment of the human question in an article that was much praised by
Darwin [Wallace, 1864]. But then disaster struck. Wallace became enamored with
spiritualism, and started to think that the world is under the control or influence
of some great force. Most particularly that the arrival of humans on this planet
was not purely natural. And in support of his position, Wallace listed several
features of humans that he thought could not possibly have been produced by
natural selection. These included things like our hairlessness and our intelligence.
Wallace had had first-hand experience of living with natives, and he knew that
they had much higher intelligence than most Victorians supposed possible, and
yet they do not generally use this intelligence to the full and so clearly it must
have arrived through processes other than selection [Wallace, 1870].
Darwin was appalled. Something had to be done, and hence his book on hu-
mankind. Much of the work was fairly straightforward and predictable, as Darwin
discussed what is known about humans and their origins. Basically, he saw no rea-
son to think that we call for anything but general processes of natural selection.
He did pay some attention to actual paths of evolution. In theOrigin, Darwin had
more or less stayed away from these kinds of questions. Although the earlier work
on barnacles was not set in an evolutionary context, the knowing reader could
with little difficulty work out how Darwin thought that their actual evolution had
proceeded. In theOrigin, Darwin had rather different fish to fry — causes —
and so he did not indulge in much path tracing (in modern language, phylogeny
tracing). In theDescent, Darwin felt able to discuss rival hypotheses and in the
end he came down to one favoring an African origin for our species. This tied in
with the romantic view that the Victorians then had of the dark (and mysterious)
continent. (TheDescentappeared in the year that H. M. Stanley discovered Dr
Livingstone at Ujiji, on the edge of Lake Tanganyika.)
Nevertheless, theDescent of Manis far from a conventional book. Taken overall,
it has a very peculiar structure and contents. Most of the book is not about humans
at all! Right from the beginning back in the early 1840s, Darwin had always
argued that there is a secondary form of selection, what he called sexual selection.
Influenced by his readings of animal breeders, Darwin saw two kinds of selection
— that for general living, as when the breeder makes a bigger cow or a shaggier
sheep, and that for competition within the species, as when the breeder makes
a stronger bull terrier or a prettier bird. The former was analogous to natural
selection and the latter analogous to sexual selection. Refining the concept, the
two breeding activities just mentioned led Darwin to distinguish between sexual
selection for male combat (the dogs fighting) and sexual selection by female choice