Even in humans, male-female coitus is an iffy route to female orgasm, Lloyd notes in her book. (She declined to be interviewed for this article.) According to research she cites, only 55 percent of women have orgasms more than half the time during intercourse, while 5 to 10 percent never have them under any circumstances.
The "tremendous variation in the manifestation of the female orgasm," says Richard Wrangham, a professor of anthropology at Harvard, "doesn't seem compatible with an evolutionary history in which it is enormously important..."
...Lloyd likewise dismisses the explicitly feminist theories of Sarah Blaffer Hrdy, professor emeritus of anthropology at the University of California at Davis. Hrdy, who been tinkering with her theories since the late 1970s, believes that the female orgasm evolved to encourage females to mate with numerous men in pursuit of those elusive fireworks. The evolutionary benefits of multiple partners? Not only would women be more likely to conceive, but men would be less likely to kill the resulting infants, since no one would be sure whose child was whose.
I can't afford to comment on this piece. But I will say that author Christopher Shea has touched upon a hot-button subject. If you've ever wondered about the "upsuck theory" or primate proclivities, this is quite an article.