Animals as Evolutionary Models of Human Sexuality in the Late 20th Century

How evolutionary biologists have defined animal courtship has had profound consequences for their understanding of how Charles Darwin’s theory of sexual selection might operate among humans. One of the most remarkable applications of evolutionary logic to human behavior came from Donald Symons’ Evolution of Sexuality, published in 1979. If male and female heterosexual reproductive strategies fundamentally differed, then Symons reasoned that every sexual encounter between a man and a woman represented a compromise between their dueling desires and agendas. How best, then, to understand true male behavioral patterns? In matches unfettered by female reluctance. For Symons the frequency of homosexual encounters was the best yardstick by which to measure normative heterosexual desire. His account reinforced gendered stereotypes already inscribed in sociobiology: males possessed a greater sex drive than females, derived from the evolutionary importance of male sexual pleasure. Critical of this argument, Sarah Blaffer Hrdy pushed back by suggesting the variety of female-female sexual encounters in primates provided robust evidence of sexual drive in all females. This paper explores these debates and subsequent transformations in late-20th-century evolutionary accounts of the match. What began as a means of naturalizing heterosexual courtship norms would eventually transform into a potential defense of gay rights as biologists documented numerous examples of same-sex behavior in animals. As a result, the logic of using any one animal as a model of human courtship gave way to seeing human sexuality as reflected in the wide diversity of sexualities found in the animal kingdom as a whole.