Physicists thought that snakes did not have clitoris. They were wrong

Female snakes also have clitoris, a new study finds.

The research raises the possibility that the sex lives of snakes are more complex and diverse than previously understood, researchers report on December 14. Proceedings of the Royal Society B..

Clitorises are found in a wide range of vertebrate life, from crocodiles to dolphins (SN: 1/10/22). The one exception is birds, which lost their clitoris during the course of evolution. It appears that female snakes have also lost their sex organ, which is puzzling, since their lizard relatives have twin clitoris, called hemiclitoris. Lizards and serpents are accompanied by phallus or hemipenis.

This element of the sexual anatomy of female snakes has been under-discussed for so long, partly because the hemiclitoris are fragile and easily missing, but also because female genitalia have historically been considered “a big taboo,” says evolutionary biologist Megan Folwell of the University of Adelaide in Australia.

“Even in humans, the proper function and significance of the human clitoris was still being discussed in 2006,” he said.

Contradictory accounts of hemiclitoris snakes in some scientific papers led Folwell to a unique perspective. She first investigated the common death of a euthanized female asp (Acanthophis antarcticus). “I just started dissecting the tail and going in with a really open mind to what I could find,” he said.

She was “pleasantly surprised” that the two organs found in male snakes were quite different from those found in male snakes. Also, unlike the hemiclitoris lizards, the snake could not emerge from the outside.

To confirm that it does not look like a mass of other tissue, Folwell and his colleagues carefully examined sections of organs under a microscope. The team also soaked the tail in iodine, which allowed the soft tissues in the genital area to be seen with greater resolution using X-rays.

These analyzes showed that the basic tissues are different from the hemipenis of the male snake. The organs were primarily filled with collagen rather than muscle fibers running throughout the structure. Another analysis showed that the organs had “deer nerves” running through them, Folwell said, suggesting they probably have a substantial sense of touch. Like other clitoris species, the snake shows a robust supply of blood.

The team expanded their study to eight snake species beyond four families, revealing a dizzying array of coastal diversity. For example, says Folwell, the hemiclitoris of the Mexican song viper.Agkistrodon bilineatus) are huge tails filling the space. “Then you see Ingram the brown snake, who was such a tender little fellow. If you didn’t know what you were looking for, it could certainly be missed,” says Folwell.

Some hemiclitoris are thin, and they put their scent on the glands, some sandwiched between or even on top of each other, he adds.

Snakes are thought to have evolved from older lizards. The findings show that, in evolutionary terms, the snake’s clitoris “wasn’t lost; it just changed,” says Diane Kelly, an evolutionary biologist at the University of Massachusetts Amherst, who was not involved in this study.

Folwell and his colleagues think that hemiclitoris are aroused during courtship and mating to behaviors such as tail twitching. This can make the female more receptive, encourage longer and more frequent copulations and increase the chances of fertilization.

“It is often believed, in snakes, of coercion, and of all manly conduct,” says Folwell. “It may be closer to rape in some species.”

Continuing, Folwell wants to look at how the nerves in the hemiclitoris are involved in all the touch sensitivity and function in intercourse.

Kelly notes that comparing the hemipenis and hemiclitoris of the same species can help give an idea of ​​the function of the organs in snakes, and reveal the potential for any subsequent and existing evolution between males and females.

“It’s 2022, and here’s a new anatomical discovery in a common animal,” says Kelly. “There’s a lot of anatomy that we still don’t know yet.”