Using paleontology, archeology, and genomics, a group of European researchers has tackled the long-debated issue of early horse domestication. According to this research team, the horse-human domestic relationship began in the grasslands of modern-day Eastern Europe, around Ukraine and Kazakhstan, and domestic herds often benefited from the addition of new, wild mares.

Despite suggestions indicating horses might have been domesticated at as many as 17 different sites worldwide, this new study points to one centralized area of domestication, said study author Vera Warmuth, PhD, researcher in the department of zoology at the University of Cambridge in the U.K. The discrepancy can be explained by a variation in the definition of domestication, she said.

"If you define every capture event of a wild female as a ‘domestication event,’ then horses were domesticated multiple times," she explained. "However, I think there is an absolutely crucial difference between the initial establishment of a domestic founder population and incorporation of wild females into already domestic stock."

In essence, Warmuth’s theory–based on genomic sampling of more than 300 modern horses throughout northern Eurasia and backed by fossil readings and archaeological finds–is that one group of humans began domesticating horses in the western Eurasian steppe, a grassy plains area of the Europe-Asian continent. This domestic herd spread among humans in other areas who then incorporated additional females from local wild herds