Scientists have been studying snake penises for years. These forked, often spiny structures shaped the understanding of snake reproduction.
In fact, researchers long assumed that female snakes didn’t have a counterpart organ—not that many of them really looked. But those who did—such as genital morphologist Patricia Brennan, who’s studied animal clitorises (including those of dolphins and lizards) for two decades—hadn’t been able to find it, writes the Atlantic’s Katherine J. Wu.
“There’s a lot known about male snake genitalia, but not so much—really anything—known about females,” Megan Folwell, a researcher at the University of Adelaide in Australia, tells New Scientist’s Corryn Wetzel. Previous studies were “kind of all over the place about whether the snake clitoris existed.”
But to Folwell, it just didn’t make sense that the clitoris, while present in all mammals, all lizards and some birds, would be missing in snakes. So, she started dissecting female snake specimens from the zoology collection at the University of Michigan to see if she could find it. And find it she did. After peeling back the skin of a death adder, the triangular structure of the hemiclitoris—a two-part clitoris also found in lizards—was “shockingly obvious,” writes Alex Fox for the New York Times.
In a new study published Wednesday in the Proceedings of the Royal Society B, Folwell, Brennan and their colleagues located and described the hemiclitores of nine snake species for the first time.
“This discovery could really change how we understand mating in snakes,” Brennan, a researcher at Mount Holyoke College, tells the Times. “It just shows how much we’ve been missing by largely ignoring female anatomy.”
The team found the organs varied substantially in size depending on species. The largest, found in the cantil viper, measured 1.2 inches long and 0.7 inches wide. The Guatemalan milk snake had much smaller hemiclitores, measuring 0.1 inches long and 0.06 inches wide, per the Times.
More research is needed to determine their exact function, but with erectile tissue and bundles of nerves, researchers suggest the organs “have functional significance in mating,” they write in the study.
“We can only speculate, and looking across other animals like dolphins, it’s used for pleasure in sex,” study co-author Jenna Crowe-Riddell, an evolutionary biologist at La Trobe University in Australia, tells the Australian Broadcasting Corporation’s Belinda Smith. “But we don't know if that’s what snakes are using it for.”
Previously, researchers assumed snake reproduction was mostly coercive, with males driving mating. Yet, the animals’ courtship includes behaviors like rubbing and twisting tails together, which researchers say may stimulate the hemiclitores and make females more receptive to reproduction.
The new study “provides indisputable evidence that [the clitoris] is there, and it’s large, and it’s complex,” Richard Shine at Macquarie University in Australia who was not involved in the study, tells New Scientist. “It’s a great leap forward in our understanding of sexual anatomy in reptiles.”
And it’s another example of the long-standing disparity between research on male and female animals and taboos around female genitalia. Even in humans, scientists didn’t fully describe the clitoris until 1998.
“Darwin described females as coy and passive participants in sexual selection … These Victorian gender notions influenced Darwin and have been with us in evolutionary biology ever since,” Malin Ah-King, an evolutionary biologist and gender researcher at Stockholm University in Sweden who was not involved in the study, tells the Times. “Each person’s perspective has limits, and this research shows how bringing in more perspectives can give us a more complete picture.”