Ever since they were mistaken for hermaphrodites, spotted hyenas (Crocuta crocuta) have been among the most misunderstood species on earth. Most people follow the lead of the Disney script-writers and cast hyenas as the bad guys of the animal world for their gruesome lifestyles.
The misconception about spotted hyenas was perpetuated well into the twentieth century by people from Hemingway to biologists, who should have known better.
The truth about spotted hyenas is arguably as bizarre as the myth. To the untrained eye, females look and act almost exactly like males. The two sexes' remarkable resemblance goes right down to the nitty-gritty of their genitals, which appear to be identical. Moreover, the females of this species seem to be even more masculine than the males: Females are some 10 percent larger by weight and are so much more aggressive that they dominate males in nearly every social encounter, a fact that the Disney studio paid only lip service to when developing "The Lion King."
More than mere curiosities, spotted hyenas challenge the conventional wisdom of what makes us female or male and so can give us insights into the limits and latitudes of our own sexuality. Many biologists who study female-male differences let their preconceptions affect their results. For instance, while testosterone and other so-called "male" hormones are quite common in female mammals, biologists almost always focus on their estrogen and other so-called "female" hormones. Despite their dog-like appearance, the three species of hyenas belong to a superfamily that includes cats, mongooses, and civets. Spotted hyenas are named for the dark brown spots that stand out against their short, brownish-yellow fur. The demented-sounding cackle they make when squabbling gives them their other common name, the laughing hyena. Spotted hyenas live in the savannas and woodlands of sub-Saharan Africa.
All three species of hyena have the long necks, powerful shoulders, and short hindlegs that give hyenas their characteristic attenuated look. Likewise, all hyenas are consummate scavengers, noteworthy for being the only carnivores that can ingest a carcass in its entirety. While carnivores' digestive tracts are typically short, those of hyenas are uncommonly long and are capable of extracting nearly all the protein and fat from bones. The mineral components of bone are reduced to a fine powder that is excreted, while the hair, ligaments, and other undigestible body parts are regurgitated in a pellet. Spotted hyenas are distinguished from their relatives in two major ways. Spotted hyenas hunt for most of their food and usually prey on large animals. A single spotted hyena can catch an adult wildebeest after chasing it three miles at speeds of up to 35 miles per hour.
The second major difference is, as already mentioned, that female spotted hyenas have in many ways adopted the orthodox male role. Female spotted hyenas bear, suckle, and care for their young like any female mammal. But although their genitals are clearly female in function, they are male in form. The labia are fused into what looks like a scrotum, complete with two pads of fatty tissue that resemble testes. In addition, the clitoris is elongated to the point that it is nearly the size of a male's penis and is likewise fully erectile. Astonishingly, females mate and give birth through the long, narrow canal running down the center of this "pseudopenis." During mating it retracts much like a shirt sleeve being pushed up, and during birth it stretches so much that it looks like a water balloon. "From a human perspective, the process can be thought of as giving birth through an unusually large penis," says biologist Laurence Frank.
While highly unusual, spotted hyenas are not as anomalous as they appear to be at first glance. Rather, they are at the extreme end of a continuum of female mammals with masculine characteristics. One-quarter of mammalian families contain species in which females are larger than males, and there are other female mammals with genitals that are masculinized to some degree. For instance, spider monkeys have a large, pendulous clitoris and the European mole has an elongated penis-like clitoris.
In addition to having male-like genitals, female spotted hyenas enjoy the social position accorded to males in most mammal species: dominance. Except for when they are ready to mate, female spotted hyenas completely dominate the adult males that join their clan. (As is true of many social mammals, female hyenas stay in the clan where they were born while males disperse when they reach puberty at about two years of age.) Most tellingly, males abandon kills once females show up--Frank has seen a single juvenile female keep five full-grown males from feeding on a buffalo carcass. Males typically skirt the edges of kill sites, snatching scraps dropped by females.
Aggression is a way of life for female spotted hyenas. "Rank is inherited from mothers, and higher-ranking females teach youngsters what their rank is through aggression," says Frank.
While many displays of dominance are just meant to show who's boss, subordinates sometimes sustain considerable damage. After being separated for a few hours, spotted hyenas engage in "greeting" displays that entail lifting their legs and exposing their erect pseudopenises for inspection. Subordinate females often initiate greetings and this is the only known case of an erection being a submissive gesture. "This unusual display is not without its risks [because] each hyena puts its reproductive organs in immediate proximity to very powerful jaws," says Frank. "On the rare occasions when the aggression escalates to fighting, the resulting damage may be severe enough to destroy or seriously compromise the reproductive competence of the injured party."
Compiled from "Sex and the Spotted Hyena" by R. Meadows