For thousands of years, donkeys have been critical to the advancement of human civilization. They have helped pull wheeled vehicles, carry travelers and transport goods around the world.
But where and when these animals first became intertwined with humans has been a mystery. Now, researchers have used the genomes of over 200 donkeys to trace their domestication back to a single event around 7,000 years ago in East Africa — about 3,000 years before humans domesticated horses. The team published their findings, which detail the story of the donkey, in the journal Science this month.
“Through their DNA, the animals tell their own stories,” says co-author Samantha Brooks, an equine researcher at the University of Florida, in a statement. “We usually only learn the human side of history through written accounts, but of course written history doesn’t always record exactly how something happened. When we look at these DNA sequences, we get a biological record of the environment these animals lived in and the experiences they had.”
The researchers examined 207 genomes from modern donkeys living in 31 countries around the world. They also examined genomes from 15 wild equidae and 31 ancient donkeys that lived between 4,000 and 100 years ago. The team reconstructed the animals’ evolutionary tree and used computer models to locate the domestication event when herders in Kenya and the Horn of Africa tamed wild donkeys. They then tracked how the animals spread across the rest of the continent and into Europe and Asia some 2,500 years later.
“This is the story of the donkeys… and the details are amazing,” says Greger Larson, an evolutionary biologist at the University of Oxford in England who was not involved in the study Science‘s Elizabeth Pennis. “I’m happy that the donkey is finally getting his day.”
The findings revealed other parts of the animal’s history: For example, at what appeared to be a donkey breeding center at an ancient Roman villa in northeastern France, people bred African and European donkeys to create “giant donkeys.” Science writes. These animals were almost 10 inches taller than a normal donkey.
Although it is still unclear why the original domestication took place, science news‘ Freda Kreier reports that the event coincided with the Sahara becoming larger and drier.
“Donkeys are masters at carrying things and are good at traversing deserts,” co-author Ludovic Orlando, an evolutionary biologist at Paul Sabatier University in France, told the publication. Prehistoric humans may have enlisted the help of donkeys to navigate the expanding Sahara.
Researchers say these findings could help put donkeys in the spotlight, per science news. The animals could benefit from more research: there are currently no published genomes of donkeys living south of the equator in Africa. But understanding where the animals were first domesticated could lead archaeologists into a narrower region to look for clues about the original tamed donkeys, according to the publication.
Understanding the horses’ genetic makeup not only helps uncover their contributions to human history, but could also improve their future management as climate change alters the planet’s environment, the authors write. There are currently around 50 million donkeys on the planet, and they remain important for agriculture and transportation.
“Donkeys are exceptional workhorses that are essential to the livelihoods of millions of people around the world,” says Emily Clark, a livestock geneticist at the University of Edinburgh in Scotland, who was not involved in the study science news. “As humans, we owe a debt of gratitude to the donkey for the role it plays and has played in shaping society.”