When Did Humans Domesticate Horses? Scientists Find Modern Lineage Has Origins 4,200 Years Ago

The domestication of horses is arguably among the most important achievements by early humans, allowing for massive advancements in travel, hunting and combat. Now, in a wide genomic study, researchers suggest they have pinpointed when and where this revolution occurred, calling into question earlier theories about the history of horse husbandry.

In a study published last week in the journal Nature, archaeologists used DNA analysis to trace horse domestication to roughly 2200 B.C.E.—about 1,000 years later than previously thought.

At that time, one particular horse lineage became dominant, they found. It emerged from the Pontic-Caspian steppe—a region of plains that stretches through modern-day Belarus, Ukraine and Russia—and spread across Eurasia in a matter of centuries. This bloodline gave rise to the domesticated horses of today.

“We saw this genetic type spreading almost everywhere in Eurasia—clearly this horse type that was local became global very fast,” Ludovic Orlando, a molecular archaeologist at the Center for Anthropobiology and Genomics of Toulouse in France and a co-author of the study, tells the Associated Press’ Christina Larson.

Orlando and the team analyzed DNA from 475 ancient Eurasian horses—some of which lived as far back as 50,000 years ago—and 77 modern, domesticated horses representing 40 different breeds and the endangered Przewalski’s horse. Comparing these findings with archaeological evidence and carbon dating, they created a revised timeline of horse and human history that may tell a more complete equine story.

Scientists previously found that some 5,500 years ago, wild horses may have first been domesticated by the Botai people—early hunter-gatherers in what is now Kazakhstan—and likely used for their milk and meat. But the culture died out without sharing their practice, and the horses again roamed free throughout central Asia.

But then, roughly 4,200 years ago, humans domesticated horses once more, according to the new research. The team suggests the Bronze Age Sintashta culture achieved this feat and quickly used the animals to move and expand throughout Eurasia. As they traveled, so did their knowledge of horse husbandry. And through the Sintashta’s breeding, a new equine bloodline emerged.

“It seems that the first [Botai] domestication was motivated by accessing meat and milk in some central Asian settled hunter-gathering group,” Orlando tells Live Science’s Kristina Killgrove. “In contrast, the other groups domesticating the horse 4,200 years ago were incentivized by mobility, since their horse bloodline expanded like no other before and since.”

The new findings also call into question another idea about early horse domestication. Last year, another team of researchers suggested the Bronze Age Yamnaya people were riding horses in the Eurasian steppe roughly 5,000 years ago. They analyzed human skeletons, five of which showed wear marks on specific bones that indicated these individuals likely rode horses.

But according to the new genetic research, horse genes did not start spreading until 800 years after the Yamnaya migrated.

This is “potentially a difficult pill to swallow for a lot in the science community,” William Taylor, an archaeozoologist at the University of Colorado Boulder who was not involved in the study, tells Science News’ Tina Hesman Saey. “The animals we know today as domestic horses did not have a presence in Yamnaya culture. … This is a hard reality that genetic evidence is able to provide.”

The ancient horse DNA also revealed evidence of human control over the animals’ reproduction. Archaeologists noted mating between closely related horses and a reduced length of time between generations, from about seven years to four years.

Generations could have gotten shorter because horses had a higher survival rate in human care. Horses reproduced in safer, more stable environments—as opposed to the open plains, where birthing foals was more dangerous and left them exposed to predators—and they were likely made to mate at younger ages.

“It must be assumed that for horses living in the care of humans, losses of mares and their newborn foals were considerably reduced in comparison to horses living under wildlife conditions,” Christine Aurich, a veterinarian at the University of Veterinary Medicine Vienna who was not involved in the study, tells New Scientist’s Christa Lesté-Lasserre.

Other livestock, such as sheep and goats, had by then already been domesticated for several thousand years—providing knowledge the Sintashta likely applied to horses.

“Humans changed the horse genome stunningly quickly, perhaps because we already had experience dealing with animals,” Laurent Frantz, an animal paleogeneticist at the Ludwig Maximilian University of Munich who was not involved in the study, tells the Associated Press. “It shows the special place of horses in human societies.”

Christian Thorsberg | READ MORE

Christian Thorsberg is an environmental writer and photographer from Chicago. His work, which often centers on freshwater issues, climate change and subsistence, has appeared in Circle of Blue, Sierra magazine, Discover magazine and Alaska Sporting Journal.