Animals Like Beauty for Its Own Sake – The Atlantic
That legacy still infects evolutionary biology today. Consider orgasms, which Prum does at length in a later chapter. “There’s an entire field on the evolution of orgasm that’s devoid of any discussion of pleasure,” he says. “It’s stunningly bad science, and once more, it places male quality at the causal center.” For example, some researchers suggested that contractions produced during female orgasm are adaptations that allow women to better “upsuck”—no, really—the sperm of the best males. Others theorists suggested that female orgasm is the equivalent of male nipples—an inconsequential byproduct of natural selection acting on the opposite sex. Both ideas trivialize the sexual agency of women, Prum says, and completely fail to engage with the thing they’re actually trying to explain–women’s subjective experiences of sexual pleasure.
“It should come as no surprise that science does such a poor job of explaining pleasure because it’s left the actual experience of pleasure out of the equation,” he writes. That is, when biologists think about mate choice, whether in manakins or people, they focus only on the outcomes of the choice, and neglect the actual act of choosing. The result is a sexual science that’s bizarrely sanitized—an account of pleasure that’s totally anhedonic.
His counter-explanation is simple: During human evolution, women preferred to have sex with men who stimulated their own sexual pleasure, leading to co-evolution between female desire and male behaviors that met those desires. That’s why, compared to our closest ape relatives, human sex is much longer, involves a variety of positions, and isn’t tied to fertility cycles. It’s also why female orgasm isn’t necessary for actual procreation. “It may be the greatest testament to the power of aesthetic evolution,” Prum writes. “It’s sexual pleasure for its own sake, which has evolved purely as a consequence of women’s pursuit of pleasure.”
By his admission, this is speculative. He hopes that his book—which also includes hypotheses about human bodies, cultural standards of attractiveness, sexual identity, and more—will spur more research that’s grounded in an appreciation of aesthetics. But he also notes that there are other species in which experiments have confirmed the power of female choice.
In 2005, a woman named Patricia Brennan joined Prum’s lab with an interest in animal genitals—and in ducks. Most birds don’t have penises, but male ducks have huge, corkscrew-shaped ones that they extrude into females at high speed. But Brennan showed that female ducks have equally convoluted vaginas, which spiral in the opposite direction and include several dead-end pockets. Why?
Duck sex is intense and violent. Several males will often try to force themselves onto a female, and they use their ballistic penises to deposit sperm as far inside their mates as possible. But Brennan, by getting drakes to launch their penises into variously shaped glass tubes, showed that a female’s counter-spiraling vagina can stop the progress of her partner’s phallus. If she actually wants to mate, she can change her posture and relax the walls of her genital tract to offer a male easy passage. As a result, even in species where 40 percent of sexual encounters are forced, more than 95 percent of chicks are actually sired by a female’s chosen partner.