Hyena

Hyenas, also called hyaenas, are feliform carnivoran mammals in the family Hyaenidae. Only four species exist today, each placed in its own genus, making this the fifth-smallest family in the order Carnivora and one of the smallest in the class Mammalia. Though not diverse in number, hyenas play a unique and essential role across most African ecosystems.

Even though they are more closely related to cats and civets in evolutionary terms, hyenas look and act a lot like dogs in several ways—a result of convergent evolution. Both hyenas and canines are ground-dwelling, running hunters that seize prey with their teeth, not claws. They both eat rapidly and may cache food, and their padded feet, with large, blunt claws that cannot retract, are built for speed and sharp turns. However, when it comes to grooming, scent-marking, defecation, mating, and raising young, hyenas behave like other feliforms.

Hyenas appear often in the folklore and mythology of people who live near them. They are usually seen as frightening and contemptible. Some cultures believe hyenas can influence human spirits, rob graves, or steal livestock and children. Others link them to witchcraft and use parts of their bodies in traditional medicine.

**Evolution**

**Origins** Hyenas first appeared in the jungles of Miocene Eurasia about 22 million years ago, when most early feliforms still lived in trees. The earliest ancestors probably resembled the modern African civet. One of the oldest known hyena species, *Plioviverrops*, was a slender, civet-like animal that lived in Eurasia 20–22 million years ago and can be identified as a hyaenid by its middle ear and tooth structure. This lineage thrived and gave rise to descendants with longer legs and sharper jaws—a path similar to that taken by canids in North America.

Later, hyenas split into two main types: lightly built, dog-like hyenas and robust, bone-crushing hyenas. The dog-like forms flourished about 15 million years ago (one even reached North America), but most died out after climate change and the arrival of canids in Eurasia. Only the insect-eating aardwolf survived from that branch, while the bone-crushing hyenas—including today’s spotted, brown, and striped species—became the top scavengers of Eurasia and Africa.

**Rise and fall of the dog-like hyenas** Descendants of *Plioviverrops* peaked about 15 million years ago, with more than 30 species identified. Unlike most modern hyenas, which are specialized bone-crushers, these dog-like hyenas were agile, wolfish animals. One example, *Ictitherium viverrinum*, resembled a jackal. They were extremely numerous; at some Miocene fossil sites, remains of *Ictitherium* and other dog-like hyenas outnumber those of all other carnivores combined. Their decline began 5–7 million years ago due to climate change, made worse by canids crossing the Bering land bridge into Eurasia. One species, *Chasmaporthetes ossifragus*, crossed into North America—the only hyena ever to do so. It survived there by becoming a cheetah-like sprinter, avoiding the endurance-running and bone-crushing niches already taken by canids. Most dog-like hyenas were gone by 1.5 million years ago.

**Bone-crushing hyenas** By 10–14 million years ago, the hyena family had split into dog-like and bone-crushing groups. The rise of ancestral bone-crushing hyenas coincided with the decline of the similar family Percrocutidae. These bone-crushers survived the climate changes and the arrival of canids that wiped out the dog-like hyenas, though they never reached North America, where the dog subfamily Borophaginae already filled that niche. By 5 million years ago, they were the dominant scavengers of Eurasia, feeding mainly on large herbivore carcasses left by sabre-toothed cats. One genus, *Pachycrocuta*, was a mega-scavenger capable of splintering elephant bones. Starting in the early Middle Pleistocene, *Pachycrocuta* was replaced by the smaller *Crocuta* and *Hyena*, likely linked to a broader faunal shift around the Mid-Pleistocene transition.

**Rise of modern hyenas** The four living species are the striped hyena (*Hyaena hyaena*), the brown hyena (*Parahyaena brunnea*), the spotted hyena (*Crocuta crocuta*), and the aardwolf (*Proteles cristata*).

The aardwolf traces its lineage directly back to *Plioviverrops* 15 million years ago and is the sole survivor of the dog-like hyena branch. Its success comes partly from its insect-eating diet, which faced no competition from canids crossing from North America. Its ability to digest the terpene secretions of soldier termites likely evolved from the strong digestive system its ancestors used to process rotting meat.

The striped hyena may have evolved from *Hyaenictitherium namaquensis* of Pliocene Africa. Its fossils are common in Africa, dating back to the Villafranchian. Since no fossil striped hyenas have been found in the Mediterranean region, the species probably spread into Eurasia relatively late, likely after spotted hyenas died out in Asia at the end of the Ice Age.