The female orgasm might have evolved as part of a biological mechanism to induce ovulation, according to findings published [September 30] in PNAS.
Female orgasm isn’t necessary for reproduction, but the complexity of the neural and hormonal responses underlying it suggest an evolutionarily ancient origin—leaving researchers to puzzle over why it’s present in humans at all.
To explore whether it might be an evolutionary throwback, the researchers turned to rabbits, which exhibit what’s known as copulation-induced ovulation, meaning that they release eggs when stimulated by sex, instead of ovulating cyclically as humans do. The researchers treated 12 female rabbits with a two-week course of fluoxetine (best known by the market name Prozac), which is known to suppress orgasms in human women. Then, they counted how many eggs were released after the animals had sex with a male rabbit, a.k.a. “Frank.”
Rabbits treated with antidepressants released 30 percent fewer eggs than control rabbits did, the team found.
The findings suggest the control of sex-stimulated egg-release in rabbits operates via similar biological pathways to the female orgasm in humans.
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