Joan Roughgarden thinks Charles Darwin made a terrible mistake. Not about natural selection—she’s no bible-toting creationist—but about his other great theory of evolution: sexual selection. According to Roughgarden, sexual selection can’t explain the homosexuality that’s been documented in over 450 different vertebrate species. This means that same-sex sexuality—long disparaged as a quirk of human culture—is a normal, and probably necessary, fact of life. By neglecting all those gay animals, she says, Darwin misunderstood the basic nature of heterosexuality.
Darwin’s theory of sex has been biological dogma ever since he postulated why peacocks flirt. His gendered view of life has become a centerpiece of evolution, one of his great scientific legacies. The culture wars over evolution and common descent notwithstanding, Darwin’s theory of sexual selection has been thoroughly assimilated into mass culture. From sitcoms to beer ads, our coital “instincts” are constantly reaffirmed. Females are wary, and males are horny. Sex is this simple. Or is it?