Among the four remaining species in the hyena family (Hyaenidae), the spotted hyena stands out in several remarkable ways. Not only do they live in matriarchal societies—ruled by females—but they also sport a pseudopenis between their legs.

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By definition, a pseudopenis is an organ—or more precisely, a structure—that superficially resembles a penis but has evolved along a different developmental pathway. Although capable of erection and sometimes reaching up to 20 centimeters in length, researchers still cannot say with certainty what its exact purpose is. However, several theories exist. In today’s article, you’ll learn about the peculiar relationship between hyenas and this strange organ.

Spotted Hyenas – Ladies First!

But first, a small clarification: why are we writing about hyenas on a cat-themed site? Apart from our selfish desire to share this fascinating story, we can justify it by pointing out that hyenas are actually the closest living relatives of the cat family—along with several other surprising species.

As mentioned above, spotted hyenas live in matriarchal societies led by alpha females. Within these clans, the females do most of the hunting, shape the social structure, and raise their cubs alone. Since most males join the clan from other groups, even the highest-ranking male is often subordinate to the youngest female. Hyena cubs are born into a brutal, competitive environment (more on that later), where they must immediately fight for dominance. If male cubs are lucky enough to reach adolescence, most leave their natal clan and begin wandering in search of another group, where they start at the very bottom of the male hierarchy.

This matriarchal system actually promotes genetic diversity: because males are lower-ranking, it’s less likely that a single male sires a disproportionate number of offspring within one clan. Dominant females, who can give birth to only a limited number of cubs and often mate with several partners, are not subject to such imbalance.

Our image of hyenas has been heavily influenced by The Lion King, where they are portrayed as sneering, cowardly scavengers. In reality, they are highly intelligent and loyal mammals that abhor waste—even during times of plenty (they’ll eat everything, right down to the hooves). Socially, they are very sensitive animals—each hyena knows every member of its clan personally. After a fight or squabble, they always reconcile. Researchers believe that their intelligence and social sophistication may even rival that of primates.

Spotted hyenas live in a pack

The Female Hyena’s “Penis” Comes with All the Usual Accessories

Mother Nature certainly has a sense of humor: the phallic structure is accompanied by false scrotums and pseudo-testes. The mimicry is so convincing that scientists once believed hyenas might be hermaphroditic. However, their internal anatomy remains unmistakably female, meaning that female hyenas must urinate, mate, and even give birth through the pseudopenis. The latter two functions are just as complicated and painful as they sound. During birth, the female must push out a 1–1.5 kg cub through a canal that’s only about 2.5 cm wide. Many females die during their first labor as a direct result of this anatomical challenge.

During mating, the male must insert his penis into this elongated canal. The reproductive tract is often blocked by the pseudo-scrotum, so the female must remain completely still during copulation. Naturally, one might ask: what on earth is the purpose of such an organ? Scientists have proposed three main theories to explain it.

Possible Reasons for the Hyena “Pseudopenis”

Female spotted hyenas have unusually high levels of androgens (male sex hormones), which are associated with dominance and social status. In fact, their testosterone levels are comparable to those of males. The dominance of females provides a clear advantage within their feeding system. Spotted hyenas gather in groups around fresh kills and feed together—sometimes more than twenty individuals competing for a single carcass. The high-ranking females and their offspring eat first, followed by lower-ranking females and their young, and finally, the adult males. In this context, high androgen and testosterone levels confer clear ecological benefits.

A Strange Ritual

Another hypothesis suggests that these extraordinary genital structures are simply evolutionary by-products of elevated steroid levels. While plausible, this idea doesn’t fully explain why females would evolve to give birth through a penis-like organ—a massive biological compromise.

An alternative theory proposes that the pseudopenis evolved partly for social reasons. High-ranking females are extremely aggressive toward both males and lower-ranking females. They enjoy better access to food and greater reproductive success. Thus, ritualized behaviors that reinforce social status may benefit both dominant and subordinate females. What kind of ritualized behavior? When female hyenas meet, they stand parallel to each other, facing opposite directions, raise their hind legs, and display their fully erect pseudopenises—sometimes sniffing or licking one another.

These rituals are strongly asymmetrical between high- and low-ranking females, suggesting that such behaviors serve as signals of status. However, researchers note that given the enormous reproductive cost associated with this organ, this explanation alone is unlikely to account for its evolution.

A mother and her cub

To Prevent Sibling Murder?

The third theory considers the intense aggression seen among newborn hyenas. Unlike most mammals, hyena cubs are not helpless or “cute.” They are born in underground dens that adults can barely access, equipped with functional incisors, large canines, and strong jaw and neck muscles. They are also highly aggressive and will attack anything that moves. Interestingly, female newborns are more prone to siblicide than males. Male cubs therefore pose less of a threat to littermates. Moreover, dominant females have been observed killing the offspring of lower-ranking females to reduce competition.

When spotted hyena cubs are born, males and females look exactly alike—even under close inspection. Their sex can only be determined using molecular methods, as their external genitalia are identical. This suggests that appearing male in early life may be advantageous for young females.

It’s entirely possible that all these explanations are true to some degree—or that there are still other reasons hidden in the unknown. One thing’s for sure: we can’t wait to learn more about this extraordinary species—and its even more extraordinary anatomy.

When Even Zookeepers Get Confused

In 2014, the Maruyama Zoo in Japan made headlines when it was revealed that keepers had spent four years trying—and failing—to breed their two hyenas. The pair had been purchased from a South Korean zoo, which had assured them they were a male and a female. After multiple unsuccessful attempts to mate them (the “couple” kept fighting instead of flirting), ultrasound and hormone tests finally revealed the truth: both animals were male.

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