Domestication

Genetic fingerprints indicate that wild African asses were the ancestors of domestic donkeys, making donkeys the only important domestic animal known to come from Africa.

Animal domestication was a key development in human culture. Meat animals came first, with cattle, sheep, goats and pigs initially domesticated between 10,000 and 11,000 years ago.

Animals useful for carrying loads and people, such as horses, donkeys and camels, came in a later wave about 5000 years ago, which enhanced trade and mobility. Donkeys were particularly important, being smaller, more durable and easier to handle and feed than horses.

The oldest remains date from 5000 to 6000 years ago in Egypt, and slightly later in Mesopotamia and Iran. However, the point of their original domestication had been unknown.

To solve the mystery, Albano Beja-Pereira of the University Joseph Fourier in Grenoble, France, visited 52 countries, collecting samples from domestic donkeys and from wild asses and their relatives in Africa and Asia.

Tamed twice

Mitochondrial DNA comparisons revealed two distinct populations of domestic donkeys. One is clearly derived from the Nubian subspecies of wild ass, Equus asinus africanus. The second is close to the Somalian wild ass, Equus asinus somaliensis, but does not fall within the wild range.

Beja-Pereira's group suggests that donkeys were most probably domesticated twice, once from each of the two existing African wild asses, which diverged hundreds of thousands of years ago. Genetic studies of other livestock species also show they were domesticated more than once.

The data clearly excludes the Asian "half-asses," Equus hemionus and Equus kiang, as possible ancestors of domesticated donkeys, says Steve Jordan of Bucknell University in Pennsylvania, US, a member of the team that analysed the relationships.