Darwin's Precursors and Influences

5. Sexual selection

by John Wilkins

Copyright © 1996-2003

[Last Update: 21 February 2003]

Previous

Contents

Next

I have not been able to find any precursors to Darwin's theory that many non-adaptive features of animals are the result not of natural selection but of mate choice. Darwin and Wallace both accepted this hypothesis, but Wallace was never able to accept that female choice was involved in, for example, the exaggerated plumage of some male birds, preferring instead the view that female drabness was due to selection for camouflage¹. Wallace claimed on this subject to be more Darwinian than Darwin himself, but I think Darwin's views are the more successful. Both agreed that male competition was a factor in sexual selection, resulting from competition for mating opportunities through contest. That there are no precursors is not surprising, since the problem doesn't arise until adaptation is explained in terms of natural selection, and this was not proposed by anyone else as a general principle of evolution. However, Darwin's grandfather, Erasmus Darwin, in his 1795 Zoonomia, gave a surprisingly sophisticated account of sexual selection:

A great want of one part of the animal world has consisted in the desire of the exclusive possession of the females; and these have acquired weapons to combat each other for this purpose ...

The final cause of this conflict amongst the males seems to be, that the strongest and most active animal should propagate the species, which should thence become improved^.2

Erasmus, however, did not offer sexualselection as a mechanism for evolution, so much as the want of this and several other things as the preconditions for evolution to occur. It may very well have influenced Darwin's own ideas, since we know he read the Zoonomia, but at best Erasmus suggested a line of thought, rather than offering a solution.

Previous

Contents

Next