Donkey

The genus Equus, which includes all extant equines, is believed to have evolved from Dinohippus, via the intermediate form Plesippus. One of the oldest species is Equus simplicidens, described as zebra-like with a donkey-shaped head. The oldest fossil to date is approximately 3.5 million years old, and was located in the US state of Idaho. The genus appears to have spread quickly into the Old World, with the similarly aged Equus livenzovensis documented from western Europe and Russia. Molecular phylogenies indicate the most recent common ancestor of all modern equids (members of the genus Equus) lived ~5.6 (3.9–7.8) mya. Direct paleogenomic sequencing of a 700,000-year-old middle…

Donkeys vary considerably in size, depending on both breed and environmental conditions, and heights at the withers range from less than 90 cm to approximately 150 cm. Working donkeys in the poorest countries have a life expectancy of 12 to 15 years; Donkeys have large ears, which may pick up more distant sounds, and may help cool the donkey's blood. Donkeys can defend themselves by biting, striking with the front hooves or kicking with the hind legs. Their vocalization, called a bray, is often represented in English as "hee haw".