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the less conspicuous variation is dotted around across all geographical areas? Could Darwin have
been right all along? Is sexual selection the answer to the paradox? The distinguished biologist
Jared Diamond thinks so, and I am inclined to agree.
What sexual selection explains, better than natural selection, is diversity that seems arbitrary, even
driven by aesthetic whim. Especially if the variation concerned is geographical. And also especially
if some of the features concerned, for example beards and the distribution of body hair and
subcutaneous fat deposits, differ between the sexes.
Most people have no problem in accepting an analogue of sexual selection for culturally mediated
fashions like headdresses, body paint, penis sheaths, ritual mutilations or ornamental clothes.
Given that cultural differences such as those of language, religion, manners and customs certainly
provide resistance to interbreeding and gene flow, I think it is entirely plausible that genetic
differences between peoples of different regions, at least where superficial, externally prominent
features are concerned, have evolved through sexual selection.
Our species really does seem to have unusually conspicuous, even ostentatious, superficial
differences between local populations, coupled with unusually low levels of overall genetic variation.
This double circumstance carries, to my mind, the stamp of sexual selection.
In this, as in so much else, I suspect that Darwin was right. Sexual selection really is a good
candidate for explaining a great deal about the unique evolution of our species. It may also be
responsible for some unique features of our species that are shared equally by all races, for
example our enormous brain. It is starting to look as though, despite initial appearances, Darwin
really was right to bring together, in one volume, Selection in Relation to Sex and the Descent of
Man.
© Richard Dawkins, 2003. This is an edited version of Richard Dawkins' introduction to a new
edition of Charles Darwin's The Descent of Man, published by Gibson Square Books, price £10.
This piece also appears in A Devil's Chaplain: Selected Essays by Richard Dawkins, published by
Weidenfeld next week, price £16.99
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