Equus

Equus is a genus of odd-toed ungulates belonging to the family Equidae, comprising the modern horses, asses, and zebras. First described by Linnaeus in 1758, the genus includes eight extant species and several extinct ones known from the fossil record. Members of Equus are characterized by a single toe (the third digit) bearing a large hoof, a long head with a mobile upper lip, and a specialized digestive system adapted for grazing on grasses.

The species are divided into three groups based on morphology and geography: true horses (Equus ferus and its domestic subspecies, E. f. caballus), African and Asian wild asses (including the African wild ass, E. africanus, and the Asian wild ass, E. hemionus), and zebras (E. zebra, E. quagga, and E. grevyi). Horses are widespread across Europe, Asia, the Americas, and Oceania, largely due to domestication. Wild asses occupy arid and semi‑arid regions of Africa and Asia, while zebras inhabit savannas, grasslands, and mountainous areas of sub‑Saharan Africa.

Equus species exhibit social structures ranging from harem-based groups in zebras to herds led by dominant stallions in horses. They possess keen senses of sight and hearing, and can run at speeds up to 70 km/h, an adaptation for predator avoidance. Reproduction is seasonal in many species, with a gestation period of around 11 months and typically a single foal per birth.

Human interaction with Equus dates back at least 5,500 years, when horses were first domesticated for transport, agriculture, and warfare. Today, horses remain central to sport, recreation, and therapy, while zebras and wild asses are primarily of conservation concern, facing habitat loss and hunting pressures. The genus is listed under various IUCN categories, ranging from Least Concern for some horse populations to Critically Endangered for several wild ass subspecies.