Donkeys were domesticated in Africa over 7,000 years ago

Domestic donkeys (Equus asinus) have been of great importance to humans for thousands of years, serving as a reliable source of animal labour and long-distance transport in many cultures.

Originally, donkeys were also used as riding animals and for pulling carts. They were later largely replaced by horses, which were faster and stronger. From that point on, donkeys hardly appear in the records of ancient cultures. The fact that donkeys continued to be used primarily as pack animals is due to their toughness. A donkey can go without water and food far longer than a horse. Donkeys were also commonly kept in mills, where they served as carriers of sacks of grain and flour. Since donkeys, unlike horses, have no fear of heights, they were and still are a preferred riding and pack animal (beast of burden) in steep mountainous terrain.

In addition to the purely physical differences from horses, donkeys have several characteristics that are not immediately apparent. Unlike horses, donkeys have five lumbar vertebrae instead of six. Donkeys have 31 chromosome pairs, while horses have 32. The body temperature of donkeys is slightly lower, averaging 37 °C compared to the usual 37.5 to 38.2 °C in horses. The gestation period in donkeys is longer than in horses, averaging 365 to 370 days compared to 330 days in horses. Differences in behavior are also significant: horses tend to flee in stressful situations, whereas donkeys tend to freeze. Female donkeys often live alone with their foals in mountainous terrain, and immediate flight is not always possible without endangering the foal. Donkeys frequently stand stock-still. Additional stress, such as from blows or shouting, tends to intensify this freezing response, which has given donkeys their reputation as particularly stubborn or dim-witted animals. This reputation, however, is unfounded. Donkeys originally inhabit rugged wastelands and rocky mountain terrain and are highly alert. They carefully assess where they place each step. Unlike the horse — a creature of open steppes — a headlong flight across steep or stony ground would spell certain death for donkeys. Donkeys are generally longer-lived than horses and can reach over 40 years of age.

Despite the key role they played in ancient pastoral societies across Africa, Europe, and Asia, and the functions they continue to fulfill today in low- and middle-income communities (particularly in semi-arid and high-altitude regions), relatively little is known about their origins, the timeline of their domestication, and the effects of human management on their genomes.

A research team led by the University of Paul Sabatier in Toulouse, France, has now conducted a comprehensive genetic analysis of both modern and ancient donkeys, shedding light on their origins, dispersal, and management practices. By analyzing 238 genomes from modern and ancient donkeys — 207 modern donkeys, 31 ancient donkeys, and 15 wild horses — the scientists found strong phylogeographic evidence for a single domestication event in East Africa.

This event was followed by a series of expansions across Africa and into Eurasia, where several subpopulations eventually became isolated and diverged from one another, likely due to the desiccation of the Sahara. Ultimately, however, genetic variants from Europe and the Middle East found their way back into West African donkey populations.

In addition, the analyzes revealed a previously unknown genetic lineage in the Levant around 2’200 years ago, which likely contributed to increased gene flow into Asian donkey populations. Finally, donkey keeping throughout history was associated with crossbreeding and the creation of large bloodlines, particularly during a period when these animals were of vital importance to the Roman economy and military.

Using computer models, the researchers estimated the relatedness of donkeys based on their DNA and concluded that the donkey was domesticated only once. This occurred more than 7’000 years ago, when herders in Kenya and the Horn of Africa began taming wild African donkeys.

By 5’000 years ago, domestication was in full swing. The first donkeys were traded northward and westward into Egypt and Sudan. Within 2’500 years, they had spread across Europe and Asia, where they developed into distinct regional populations.

Greger Larson, an evolutionary biologist at the University of Oxford who was not involved in the study, finds this new research and its details remarkable. The new work not only clarifies how many times donkeys were tamed, but also shows that donkeys were never bred through inbreeding, as was the case with horses. And Larson is pleased that the donkey has finally received the recognition it deserves.

The study was published in the journal Science.