Finally, the donkey family tree – 03/19/2023 – Science

The donkey is a key, albeit increasingly marginalized, character in human history. Once revered, the animal has been the object of ridicule for so long that the word “asinine” — derived from the Latin “asinus”, meaning “like an ass or ass”— means “stupid”. Donkeys and their work are essential to people’s livelihoods in developing countries, but elsewhere they have all but disappeared.

“I think we’ve simply forgotten the importance of this animal, probably overwhelmed by the impact of its close cousin the horse,” said Ludovic Orlando, director of the Center for Anthropobiology and Genomics in Toulouse, France.

“In Europe, the horse provided rapid mobility and helped with farming and warfare. I’m not sure we can say that the impact of the donkey was as great.” Compared to horses and dogs, donkeys have received relatively little attention from archaeologists, let alone geneticists.

However, despite this being the Year of the Rabbit according to the Chinese zodiac, it might just be the Year of the Donkey. The Oscar-nominated film “EO” features a heartbreaking and savagely abused donkey as its hero. And donkeys star in an important new genetic study published in the journal Science. Peter Mitchell, an Oxford archaeologist who was not involved in the project, called it “the most comprehensive study of donkey genomics to date.”

Orlando, who has spent years charting the history of horse domestication, is the author of the paper, which he hopes will spur research on the humble donkey and restore some of its dignity. He and researchers from 37 laboratories around the world analyzed the genomes of 207 modern donkeys, living in 31 countries. They also sequenced DNA from the skeletons of 31 ancient donkeys, some of which date back 4,500 years.

Scholars had already identified three potential centers of domestication, in the Near East, northeast Africa (including Egypt) and the Arabian Peninsula. But Orlando’s team concluded that donkeys—humanity’s first means of land transportation—were domesticated only once, around 5000 BC, when pastoralists in the Horn of Africa and present-day Kenya began taming wild donkeys. That date is about 400 years before the first archaeological evidence of domesticated donkeys at El Omari, near Cairo, and nearly three millennia before horses were first harnessed.

The period coincided with the one in which the Sahara grew and became more arid. Donkeys are especially drought-resistant and tolerant of water deprivation, which led Orlando to speculate that they became an indispensable means of transportation for the herders and their produce. “Finding a transport helper in these increasingly difficult conditions likely spurred the domestication process.”

From this point of origin in northeast Africa, the team reconstructed the evolutionary tree of donkeys and traced their dispersal routes across the rest of the continent. Donkeys were traded northwest into present-day Sudan and then Egypt, moving out of Africa around 5,000 years ago and expanding into Asia and Europe around 500 years later. The various donkey populations became more isolated by distance, although trade resulted in systematic moves back to Africa. Crossbreeding between lineages was limited.

A 2004 study of a small sample of modern DNA from hundreds of donkeys suggested that humans domesticated wild donkeys twice, in Africa and Asia. Lead researcher Albano Beja-Pereira, a geneticist at the University of Porto in Portugal, worked with Orlando and his colleague Evelyn Todd to review the findings using a larger dataset, and now agrees with the unique domestication hypothesis.

For our ancestors, the donkey assumed an extremely varied mythical and religious dimension. In ancient Egypt, it was one of the sacred animals of Seth, the Lord of Chaos. In Greek folklore, a donkey—an equine animal involved in harvesting and winemaking—was the mount that carried the god Dionysus into battle against the giants, and flutes made from donkey shinbones (which produced a braying sound) were used in their worship.

Donkeys are central to Jewish, Christian and Muslim iconography: in the Old Testament, Balaam’s donkey saw an angel and muttered prophecies. In the New Testament, Jesus rode into Jerusalem on a donkey on the day Christians celebrate Palm Sunday. Ya’fur was the name of the donkey that the prophet Mohammed would have ridden and talked with him, according to reports.

During the Bronze Age, from 3300 BC to 1200 BC, donkeys were sometimes buried with humans, indicating a bestowal of honor on both parties. “In other cases, we found them as ritual deposits under floors, as recently discovered at Tell es-Safi, or apparently buried alone,” said Laerke Recht, an archaeologist at the University of Graz in Austria who also worked on the new study. She cited a term that dates back to at least the second millennium BC: “killing an ass,” which means signing a treaty, an act that apparently involved sacrifice.

The new discoveries reveal a previously unknown lineage of donkeys present in the Levant around 200 BC At an archaeological site on the grounds of a Roman villa in the French village of Boinville-en-Woëvre, 280 km from Paris, researchers found what appears to been a donkey breeding center where West African animals were mated with their European counterparts. The resulting pack animals measured 155 centimeters from ground to withers. The current standard is 130 centimeters. The only comparable modern donkeys are American Mammoth Jacks—large, sturdy males bred to produce draft mules or for agricultural work.

Orlando said that the production of giant asses bloodlines occurred at a time when mules — the infertile daughters of male asses, or jacks, and mares — were vital to the Roman economy and its military. “It wouldn’t take that many generations to selectively breed bigger and bigger donkeys,” said Dean Richardson, professor of equine surgery at the New Bolton Center at the University of Pennsylvania School of Veterinary Medicine. “Giant donkeys have always been sought after to make more valuable mules.”

In his 2008 travelogue “The Wisdom of Donkeys,” British academic Andy Merrifield notes that Benjamin, the skeptical donkey in George Orwell’s “Animal Farm,” just wants to retire to a pasture with his friend, a horse named Boxer. Merrifield finds in the eyes of an ass “a moving sadness, a grace” and a purity that “has no right to exist in the human world”.

Still, the lucrative trade in donkey skins, an often illegal, unregulated and booming global industry, encourages intensive farming to harvest hides, which are boiled down to make “ejiao”, a gelatin used mainly in traditional Chinese medicines. “This obviously goes against animal welfare and poses a threat to local donkey populations and those who depend on this animal for their livelihood,” said Orlando. “In any case, our work reveals that our relationship with the animal goes back a long way. This should help us to realize the many services they have performed to humanity and possibly make us grateful.”

^{Translated by Luiz Roberto M. Gonçalves}