Do Female Hyenas Have a Penis? The Anatomical Facts

Female spotted hyenas do not have a penis, but they do possess an elongated, erectile clitoris so similar in outward appearance to the male penis that distinguishing the sexes by sight alone is genuinely difficult, even for experienced field researchers. This structure, commonly called a pseudopenis, is large enough that the female mates, urinates, and gives birth through it. No other living mammal reproduces this way, which is why the spotted hyena has fascinated and confused people since antiquity.

What the Pseudopenis Looks Like

From the outside, the female spotted hyena’s clitoris and the male’s penis are strikingly alike. Both are roughly the same size and shape in both flaccid and erect states, and both have a single opening at the tip of the glans.¹ The most obvious external difference is the shape of the glans itself: in females it is wide and blunt, while in males it tapers to a narrower tip. Females also have fused, fat-filled labial tissue that forms what is often described as a “false scrotum,” completing the visual mimicry of male genitalia.²

Both the penis and the clitoris have a thick collagenous capsule surrounding their main erectile body, which gives the phallus a degree of rigidity even when it is not erect. This structural stiffness also exists in females who have never given birth.³ The same study identified additional patches of erectile tissue in the glans of both sexes that appear to account for a partial “locking” of the male into the female during the later stages of mating, not unlike what happens in some canid species.

Beneath the surface, though, the differences are significant. In the male, the urethra exits on the top surface of the glans, surrounded by large, chisel-shaped bodies of supportive tissue and encased in a thick capsule. In the female, the urogenital opening sits on the underside of the glans clitoris, and the canal behind it is dramatically different: wide, pleated, and lined with highly folded tissue that can stretch enough for a fetus to pass through.⁴ The female’s canal also lacks the spongy erectile tissue and the thick capsule that tightly constrain the male urethra. In short, the engineering under the hood is built for very different purposes even though the hood itself looks the same.

How Reproduction Works Through the Clitoris

The spotted hyena is the only living mammal in which both mating and birth take place through a pendulous, penis-like clitoris.⁴ To mate, the female must voluntarily retract her clitoris, creating an opening into which the male can insert his penis. This is not a simple act: the male typically needs multiple attempts and a fair amount of cooperation from the female. The mechanics give females considerable control over who mates with them and when, and researchers have argued that this anatomical arrangement links directly to the species’ female-dominated social structure, since males must invest time building relationships with females before mating becomes possible.⁵

Giving birth through the clitoris is far more perilous than mating. The birth canal is the urogenital canal running through the clitoris, which is long, narrow at certain points, and must stretch enormously to let a cub pass. First-time mothers face serious risks. The clitoral tissue often tears during the first delivery, and cub mortality during first births is high. The pleated, redundant mucosal lining described in anatomical studies is an adaptation that allows the canal to expand, but even so, the passage is punishing.⁴ Subsequent births tend to go more smoothly because scar tissue from the first delivery permanently widens the canal.

What Causes the Clitoris to Grow So Large

For decades, the prevailing explanation was simple: female spotted hyenas are exposed to unusually high levels of androgens (male-type hormones), and those androgens enlarge the clitoris in the womb. The truth is more complicated and, in some ways, the opposite of what you might expect.

Detailed studies of fetal development show that the phallus begins forming well before the fetus can produce its own sex hormones. By about 30 to 32 days of gestation, the genital structures of both male and female fetuses are well formed, prominent, and similar in size. At that stage, the fetal gonads are completely undifferentiated, with no evidence of hormone-producing cells or androgen output.⁴ This means the initial formation and elongation of the clitoris happens without any measurable influence from fetal androgens. In other words, the basic blueprint for a large, pendulous phallus appears to be built into the genetic program of the species rather than being hormonally “masculinized” during early development.

That said, androgens do matter later. Continued growth of the phallus after birth and certain internal features of the adult genitalia, such as the shape of the supportive tissue structures and some surface characteristics, are androgen-dependent. These are the features that ultimately create the measurable differences between the adult penis and the adult clitoris.⁴ So androgens shape the details and account for the dimorphism between male and female genitalia, but they are not the reason the clitoris is large in the first place.

Where do the androgens that adult females carry come from? Adult female spotted hyenas have notably high plasma androgen levels compared to females of other species.² During pregnancy, researchers have proposed a mechanism in which androstenedione secreted by the mother’s ovary is converted to testosterone by the placenta and transferred to the developing fetus.⁶ This maternal-placental pathway may influence certain prenatal features, but as the developmental timing shows, the large clitoris itself is already present before these hormones could be responsible for it. The picture that has emerged over years of research is one where genetics set the stage and hormones paint the finer strokes.

The Social Life of the Pseudopenis

Spotted hyenas live in large, complex social groups called clans, and females outrank virtually all males. The pseudopenis plays a visible role in social interactions beyond reproduction. Spotted hyenas engage in greeting ceremonies in which two individuals stand parallel, head to tail, and each presents an erect phallus for the other to sniff and inspect. Both males and females do this, and allowing another hyena access to such a vulnerable, sensitive structure appears to signal trust and social submission. The individual who initiates the display and holds still is typically the subordinate one. These ceremonies are genuinely risky: the exposed organ could easily be injured, and that mutual vulnerability seems to be the point.

The link between the pseudopenis and female dominance has generated a lot of debate. Some researchers have connected elevated androgen levels in females to their aggressive, dominant behavior. Early endocrine work found high androgen concentrations in adult female spotted hyenas and suggested these hormones were associated with their aggression and ability to dominate males.² Others have argued that the relationship between androgens, the pseudopenis, and dominance is not as straightforward as a simple “more testosterone equals more aggression” story. Female dominance in spotted hyena clans involves a strong social-learning component: daughters inherit their mother’s rank through a process of coalition support, not purely through hormonal aggression. The pseudopenis may be more a consequence of the species’ evolutionary history than a direct tool of social dominance.

Why Only Spotted Hyenas

There are four living species in the hyena family: the spotted hyena, the striped hyena, the brown hyena, and the aardwolf. Despite being close relatives, only the spotted hyena displays the full set of masculinized external genitalia in females.⁴ Female striped hyenas, brown hyenas, and aardwolves have unremarkable, typically shaped clitorises. This means the trait evolved after the spotted hyena lineage diverged from the others, and it raises the question of what selective pressures drove such an unusual feature in just one branch of the family.

Several evolutionary hypotheses have been put forward over the years. One suggests that the enlarged clitoris is a byproduct of selection for large, aggressive females in a species where competition over food is fierce: if the genes that promote female size and aggressiveness also happen to promote androgen exposure or genital growth, the pseudopenis could be evolutionary baggage rather than a directly selected trait. Another hypothesis focuses on the mating-control angle: a clitoris that must be retracted to allow copulation gives females a physical veto over unwanted mating attempts, which could be strongly favored in a species where males are potentially dangerous. A third, somewhat older idea is that the visual similarity between males and females helps reduce aggression between the sexes. None of these are mutually exclusive, and the developmental evidence showing that early phallus growth is androgen-independent complicates the simplest hormonal explanations.

Common Misconceptions

The most persistent myth is that female spotted hyenas are hermaphrodites, possessing both male and female reproductive organs. This idea goes back to ancient Greek and Roman writers and persisted in European natural history for centuries. In reality, female spotted hyenas have perfectly standard ovaries and a uterus. They do not produce sperm. They are fully female mammals with unusual external anatomy, not organisms with mixed reproductive organs.

A related misconception is that the pseudopenis means females are “more male than female” or that something has gone wrong hormonally. The developmental research tells a different story: the large clitoris forms on its own genetic timetable, before the fetus even has functioning gonads, and the basic plan for this structure does not depend on abnormal hormone exposure.⁴ From the spotted hyena’s perspective, having a large, erectile clitoris is entirely normal female development, not a deviation from it.

People also sometimes assume that the trait must make reproduction easy or at least neutral for females. It does not. As described earlier, first-time birthing through the clitoris is dangerous, and the death rate for firstborn cubs is substantially higher than in later litters. There is a real biological cost to this anatomy, and the fact that it has persisted despite that cost tells evolutionary biologists that whatever advantages it provides, whether through mating control, social signaling, or some other pathway, must be substantial.

Sexing a Spotted Hyena in the Field

Given how similar the external anatomy looks, researchers and wildlife managers have historically struggled to determine the sex of individual hyenas, especially at a distance. Field biologists have developed a few practical tricks. The shape of the glans is one indicator: blunt and rounded in females, more tapered in males.¹ The presence of visible nipples can also help, since females nurse their cubs. Behavioral cues are useful too: in a clan setting, the largest and most socially central individuals tend to be high-ranking females. But none of these are foolproof on a single sighting, and misidentifications have been well documented in field studies.

In captive settings, veterinarians can use ultrasound or palpation to find the testes, which in males descend into a true scrotal sac, unlike the fat-filled false scrotum of females. Genetic sexing through blood or tissue samples provides certainty when visual methods are ambiguous. For zoo populations, accurate sexing matters for breeding programs, and misidentifying a male as female, or the reverse, can lead to years of confusion about why certain pairs are not reproducing.

What Spotted Hyenas Have Taught Comparative Anatomy

Beyond its inherent weirdness, the spotted hyena’s pseudopenis has become a valuable model for understanding how genitalia develop in mammals more broadly. The finding that early phallus formation is androgen-independent in spotted hyenas challenged assumptions that were long held about genital development in all mammals. In standard textbook models, the presence or absence of androgens during a critical window is what determines whether a genital tubercle develops into a penis or a clitoris. The spotted hyena shows that the situation is more nuanced: the initial growth of the structure can be genetically programmed, with hormones refining and differentiating it later.⁴

Neuroanatomical comparisons between human and spotted hyena urogenital anatomy have also informed clinical discussions about conditions in which human females are born with ambiguous genitalia. Researchers studying a condition called persistent urogenital sinus, where the urinary and reproductive tracts share a common channel, have used the hyena as a natural animal model because the basic layout resembles what surgeons encounter in affected human patients.¹ Studying how the hyena’s urogenital canal accommodates both mating and birth has given surgeons a biological reference point for thinking about nerve distribution and tissue architecture when planning reconstructive procedures. The spotted hyena is strange, but its strangeness has turned out to be scientifically productive in unexpected ways.