For biologists, few phenomena hold as much mystery as the female orgasm, writes Carl Zimmer in The New York Times. While clearly a source of intense pleasure, the purpose of the experience in terms of reproduction has not been well understood.
One thing that is known is that the muscle contractions that occur during orgasm are not necessary for reproductive success — which, from an evolutionary point of view, is just as well, as a 2010 survey recorded 36.5 percent of women saying they had not had an orgasm the most recent time they had sex.
But on Monday, in The Journal of Experimental Zoology, two scientists made the case that the human female orgasm has a deep evolutionary history, that reaches back to early mammals. Dr. Mihaela Pavlicevic, an evolutionary biologist at University of Cincinnati College of Medicine and her colleague, Gunter P. Wagner of Yale University, focused on the fact that women release an egg each month, while other female mammals, including rabbits and camels, release an egg only after mating.
Ovulatory cycles evolved in only a few mammal lineages, including ours. Before then, our ancient mammal ancestors — whose clitorises were found inside their vaginas — relied on ovulation triggered by sex with a male. The scientists argue that the female orgasm first evolved as a reflex to help females become pregnant, by signaling the brain to trigger hormones that released an egg.
As mammals, including primates like us, began to live in social groups and have access to regular sex, orgasm to stimulate ovulation was no longer useful and a new system evolved — simply releasing eggs in a regular cycle.
However, while the new theory may illuminate how the orgasm evolved in women, it doesn’t definitively clarify its current role. Elisabeth A. Lloyd, a philosopher and author of The Case of the Female Orgasm — a skeptical review of 18 theories about its function — welcomes the new paper, “because people are going to start talking about female orgasms and getting a fresh look at how much we don’t know about female orgasms, and thinking hard about what we need to know.”
The iconic restaurant scene from When Harry Met Sally only deepened the mystery of the female orgasm …
Read the full story at The New York Times.