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Ancient DNA identifies donkey ancestors, people who domesticated them

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The ancestors of the domestic donkey were considered vital for collecting water, moving desert households and creating the first land-based trade routes between the ancient Egyptians and the Sumerians, says Fiona Marshall, PhD, professor of anthropology in Arts & Sciences.

Genetic investigators say that the partnership between people and the ancestors of today’s donkeys was sealed not by monarchs trying to establish kingdoms but by mobile, pastoral people who had to recruit animals to help them survive the harsh Saharan landscape in northern Africa more than 5,000 years ago.

The findings were reported this month by an international research team, including Fiona Marshall, PhD, professor of anthropology in Arts & Sciences, in Proceedings of the Royal Society B. The study paints a surprising picture of what small, isolated groups of people were able to accomplish when confronted with unpredictable storms and expanding desert.

Sorting through the most comprehensive sampling of mitochondrial DNA ever assembled from ancient, historic and living specimens, scientists determined that the critically endangered African wild ass — which today exists only in small numbers in eastern Africa, zoos and wildlife preserves — is the living ancestor of the modern donkey.

What’s more, researchers found evidence to suggest that a subspecies called the Nubian wild ass, presumed extinct late in the 20th century, is not only a direct ancestor of the donkey — it may still exist.

The ancestors of the domestic donkey were considered vital for collecting water, moving desert households and creating the first land-based trade routes between the ancient Egyptians and the Sumerians, says Marshall, co-author on the study.

An Old World prehistorian, Marshall has documented evidence of the donkey’s domestic service by looking at skeletal wear and tear of animal remains found entombed near Egyptian pharaohs.

In the new study, scientists traced the family trees of the domestic donkey using samples from living animals, skeletons of African wild ass held in museums worldwide and isolated donkey bones from African archaeological sites.

“These were the first transport animals, the steam engines of their day,” Marshall says. “Today, domestic donkeys are often conceived of as animals of poor people, and little is known about their breeding. This is the first study to determine the African wild ass, which includes the Nubian strain, is the ancestor of the domestic donkey. That’s important to know for efforts to preserve the species.”

Placing the domestication of the donkey in northern Africa helps scientists better understand the archaeological record and early culture of the area, researchers say.

Besides revealing that the African wild ass is the living ancestor of today’s domestic donkeys, the genetic evidence also reveals that the Somali wild ass, of which about 600 exist in the wild, is not a living ancestor as once suspected, but closer akin to a more modern cousin.

That leaves a question of a remaining, yet unidentified ancestor of modern donkeys believed to have sprung from a different branch of the family. Researchers suspect that ancestors of this animal are extinct, but they may have roamed the Maghreb of northeastern Africa, and possibly the coast of Yemen.

The research was initiated by funding from the National Science Foundation and also supported by the Wildlife Trust, Saint Louis Zoo, Basel Zoo, Liberec Zoo and Sea World and Busch Gardens Conservation Fund.

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