Modern Exile

Sexual selection theory has been haunted by unconstructive critics. Whenever a new sexual selection idea raised its head, there was always an eminent biologist ready to knock it down. Wallace attacked female choice in animals, and Westermark attacked female choice in humans. After Fisher proposed his ideas about fitness indicators and the runaway process, the eminent biologist Julian Huxley attacked those too, in two widely influential papers criticizing sexual selection in 1938.

In the space of a few pages, Huxley managed to confuse sexual selection with natural selection, and failed to distinguish natural selection due to competition between individuals and natural selection due to competition between species. He argued that sexual ornaments are immoral because they undermine the good of the species, and if they are immoral, they must not really be sexual ornaments after all, but threat displays, or signals to prevent breeding between species, or perhaps something else. More damage was done by Huxley's popular 1942 textbook Evolution: The Modern Synthesis, which cast sexual selection in a marginal, even criminal role in evolution. After mentioning that biologists used to presume that bright colors displayed in courtship were products of sexual selection, Huxley observed that "It was rather the opposite of the presumption of British law that a prisoner is to be regarded as innocent until definite proof of guilt is adduced." Huxley apparently despised sexual selection because he thought it was bad for species, and he thought evolution should be for the good of species. He defined evolutionary progress as "improvement in efficiency of living" and "increased control over and independence of the environment." Since sexual ornaments had high costs that undermined survival chances and did not help an animal cope with the hostile environment, Huxley viewed them as anti-progressive, degenerate indulgences. His contempt for sexual selection combined Puritan prudery and socialist idealism with anxieties about the supposed degeneration of North European races—an ideological cocktail popular among biologists at the time.

After Huxley, the cause of sexual selection foundered again. The years from 1930 to about 1980 saw it exiled to the hinterlands of biology. Unlike the turn-of-the-century exile, this later rejection was not due to a general neglect of evolutionary theory On the contrary, the Modern Synthesis of the 1930s and 1940s revived Darwinian selection ideas by showing how they could be reconciled with Mendelian genetics. In many ways, this was a golden age for evolutionary theory. Biologists now had proofs and mathematical insights, just as physicists did. Theoretical population genetics was thriving. Darwin was every biologist's hero again— but he was now regarded as a fallible hero, prone to endearing blunders like the hypothesis that female animals select their sexual partners by aesthetic criteria.

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