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How are horses related to zebras and asses?

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horse Standardbred gelding with dark bay coat.

Horses, zebras, and asses are closely related as members of the same biological family, Equidae, and the same genus, Equus.12

These animals share several physical characteristics, including being long-legged, running mammals with a single functional digit (hoof) on each foot and high-crowned teeth adapted for grinding vegetation. Their evolutionary history is well-documented, tracing back to a common ancestor that lived millions of years ago.34

While they belong to the same genus, they are distinct species:
* Horses: Modern horses are classified as Equus caballus.2
* Zebras: There are three distinct species, including the Grevy’s zebra, mountain zebra, and plains zebra.12
* Asses: This group includes the donkey (E. asinus) and various wild species such as the African wild ass and the Asiatic wild ass.125

Because they are closely related, they can sometimes interbreed to produce hybrids, such as the mule (the offspring of a male donkey and a female horse).15