The domestication of wild horses had a profound effect on human history — offering nutrition, transportation and a leg up in warfare, among other advantages. But there are still many unanswered questions about when and where our species began its long love affair with horses. A new genetic study offers some clues. Through the first complete analysis of equestrian mitochondrial DNA — a kind of genetic material that is passed directly from mother to offspring — an international group of scientists was able to trace all modern horses to an ancestor that lived about 140,000 years ago.
After horse domestication began about 10,000 years ago, the study also discovered, horses diverged into at least 18 distinct genetic lines. Those findings suggest that, unlike cows and other animals, horses may have been tamed independently in many different places around Europe and Asia. The new research could help scientists decode the genetic secrets of modern horse breeds and top racehorses.
“Horse domestication had major cultural, socioeconomic, and even genetic implications for the numerous prehistoric and historic human populations that at different times adopted horse breeding,” said Alessandro Achilli, a geneticist at the University of Perugia in Italy. “Thus, our results will have a major impact in many areas of biological science, ranging from the field of animal and conservation genetics to zoology, veterinary science, paleontology, human genetics and anthropology.”
Cows, sheep, and goats had simple beginnings as livestock, with evidence suggesting that a small number of animals of each species were domesticated in just a few places between about 8,000 and 10,000 years ago. Today, genetic diversity among these creatures remains low. Horse DNA tells a different story, according to a new paper published today in the Proceedings of the National Academy of Sciences. After analyzing mitochondrial DNA from a wide range of horse breeds across Asia, Europe, the Middle East and the Americas, and then using the known mutation rate of this kind of DNA as a sort of clock, Achilli and colleagues were able to connect all modern horses to a common ancestor that lived between 130,000 and 160,000 years ago. By comparison, modern humans first evolved about 200,000 years ago.