Why Do Women Have Orgasms?

Much as women's breasts have fascinated many male, evolution-minded theorists, the female orgasm has confounded them. Like breasts, female orgasm is a major head-scratcher for mainstream narratives of human sexual evolution. It's not necessary for conception, so why should it exist at all? For a long time, in fact, scientists claimed that women were the only female animals to experience orgasm. But once female biologists and primatologists arrived on the scene, it became obvious that many female primates were indeed experiencing full-on, wake-the-neighbors orgasms.

The underlying motivation for claiming that female orgasm was unique to human beings probably lay in its central role in the standard narrative of human sexual evolution. According to this view, orgasm evolved in the human female to facilitate and sustain the long-term pair bond at the heart of the nuclear family. Once you've swallowed that story, it becomes problematic to admit that the females of other primate species without a hint of nuclear families are orgasmic, too. Your problem gets worse if the most orgasmic species happen to be among the most promiscuous as well, which appears to be the case.

As primate sexuality expert Alan Dixson writes, this monogamy-maintenance explanation for female orgasm "seems far-fetched." "After all," he writes, "females of other primate species, and particularly those with multimale- multifemale [promiscuous] mating systems such as macaques and chimpanzees, exhibit orgasmic responses in the absence of such bonding or the formation of stable family units." On the other hand, Dixson goes on to note, "Gibbons, which are primarily monogamous, do not exhibit obvious signs of female orgasm." Although Dixson classifies humans as mildly polygynous in his survey of primate sexuality, he seems to have doubts, as when he writes, "One might argue that . . . the female's orgasm is rewarding, increases her willingness to copulate with a variety of males rather than one partner, and thus promotes sperm competition."

Donald Symons and others have argued that "orgasm is most parsimoniously interpreted as a potential all female mammals possess." What helps realize this "potential" in some human societies, argues Symons, are "techniques of foreplay and intercourse [that] provide sufficiently intense and uninterrupted stimulation for females to orgasm." In other words, Symons thinks women have more orgasms than mares simply because men are better lovers than stallions. Stomp your foot three times if you believe this.

In support of his theory, Symons cites studies like Kinsey's showing that fewer than half of women questioned (Americans in the 1950s) experienced orgasm at least nine out of ten times they had intercourse, whereas in other societies (he refers to Mangaia, in the South Pacific), elaborate and extended sexual play result in nearly universal orgasm for women. "Orgasm," Symons concludes, "never is considered to be a spontaneous and inevitable occurrence for females as it always is for males." For Symons, Stephen Jay Gould, Elisabeth Lloyd, and others, some women have orgasms sometimes because all men do every time. For them, the female orgasm is the equivalent of male nipples: a structural echo without function in one sex of a trait vital in the other.

This seems highly unlikely.

Some of this material appears in Sex at Dawn, where we explore more likely explanations for the female orgasm in humans and other mammals.