Only four species left from a once dog-like dynasty
Hyenas form the tiny family Hyaenidae—just four living species, each in its own genus—yet they shape many African ecosystems. Phylogenetically closer to cats and viverrids, they hunt and run like dogs through convergent evolution, while grooming and parenting still follow feliform rules.
The living quartet is the striped hyena (Hyaena hyaena), brown hyena (Parahyaena brunnea), spotted hyena (Crocuta crocuta), and insect-eating aardwolf (Proteles cristata). Ancestors arose in Miocene Eurasian jungles about twenty-two million years ago; early forms such as Plioviverrops looked civet-like. The line then split into lightly built dog-like hyenas and robust bone-crushers. Dog-like forms peaked around fifteen million years ago with more than thirty named species—Ictitherium remains sometimes outnumber all other carnivores at Miocene sites—then crashed as climates shifted and canids entered Eurasia via Beringia five to seven million years ago.
Only the aardwolf survives that cursorial branch, tracing back toward Plioviverrops and digesting soldier-termite terpenes that deterred canine competitors. Bone-crushers inherited the scavenger niche; Pachycrocuta, a roughly 110-kilogram mega-scavenger, could splinter elephant bone before smaller Crocuta and Hyena replaced it in the Middle Pleistocene. Spotted hyenas diverged from striped and brown lines about ten million years ago, evolving pack hunting with sharp carnassials behind crushing premolars, then spreading from Europe to southern Africa and China.
Folklore often paints hyenas as grave-robbers or witchcraft familiars. Genomics tell a quieter story: olfactory receptor expansions in all four species, immune-gene expansions tied to scavenging in the three bone-crushers, and toxin-response gene expansions in aardwolves linked to feeding on Trinervitermes termites. Europe’s spotted hyenas vanished after the last glacial period; climate change alone does not explain the loss, and human pressure is among the factors still debated.
Source: Hyena
