Findings from a Yale-affiliated study indicate that the female orgasm evolved from ovulation in mammals and that it plays no functional role in reproduction in humans.

Researchers have discovered that female orgasm evolved from an ovulation-triggering mechanism in animals like rabbits, cats and camels that no longer exists in humans. Although the female orgasm likely has larger and more important purposes that are not yet understood, the study examined a long-stigmatized dialogue in science about female sexuality through experimental tests.

“The orgasm has only been seen under the narrow perspective of reproduction that has prevented people from looking at this in a broader context,” said Günter Wagner, the study’s senior author and Yale professor of ecology and evolutionary biology and obstetrics, gynecology and reproductive sciences.

In humans, some selective serotonin reuptake inhibitors — or antidepressants such as Prozac — can inhibit orgasms in females. The study, first published in the journal Proceedings of the National Academy of Sciences on Sept. 30, tested whether other mammals have similar responses to the drug in order to uncover a possible evolutionary connection. Because orgasms in female rabbits are tied to ovulation, the researchers administered Prozac to rabbits and monitored their ovulation rates. The team found these rabbits had a 30 percent decrease in ovulation when given the SSRI, responding to the drug similarly to women and suggesting an evolutionary connection to the human female orgasm.

Female sexuality is a complex and important topic, said the study’s first author and professor for theoretical biology at the University of Vienna Mihaela Pavlicev. This study shows that human female sexuality is not necessarily tied to reproduction, with the research instead suggesting it should be explored and understood outside of reproduction.

“It points in a direction that supports the idea that female sexuality is more than reproduction, which is hugely important,” Wagner said.

To outside experts in the field, the team’s findings are impressive. Penn State anthropology professor, David Puts called the research “convincing” and “compelling,” adding that Yale’s findings provide experimental evidence that the female orgasm evolved from an ancestral
evolutionary trait.

Additionally, Elisabeth Lloyd, a distinguished professor of biology and philosophy at Indiana University Bloomington, said the paper is a great experimental test of the evolutionary origins of the female orgasm.

Still, much remains unanswered about the female orgasm. Pavlicev said science is just starting to understand the complexity of female sexuality. And researchers remain unsure if the female orgasm stems from intrauterine development before sex is established or if it evolved separately.

In the future, Pavlicev and Wagner aim to expand their study to understand the function of orgasms in other species. Although this study is foundational in providing experimental evidence for the evolution of the female orgasm, more questions can be asked, Lloyd said. For example: Why do male humans also experience decreased ejaculation on SSRIs as well? How are male and female orgasms different? When did female orgasms diverge from the type of ovulation-triggering we see in rabbits?

The female orgasm is closely tied to the central nervous system.

Arielle Biro | arielle.biro@yale.edu

Correction: A previous version of this article stated that Mihaela Pavlicev is a former Yale postdoctoral research. In fact, she did not do postdoctoral research at Yale. The article has been updated to reflect this.