The story of how wild horses were tamed and domesticated by humans has never been told before. New genetic research by biologists at UCLA and three Swedish universities now reveals some of this history.
The biologists, writing in the Jan. 19 issue of the journal Science, show that today's domestic horse resulted from the interbreeding of many lines of wild horses in multiple locations.
The taming of wild horses was extensive and widespread, and not confined to a small area and a single culture, said Robert Wayne, a UCLA professor of organismic biology, ecology and evolution, and a co-author on the study. The domestic horse has ancient and diverse origins. We found a huge diversity in DNA sequences.
Because many characteristics of wild animals must be suppressed so they can live alongside humans, many biologists believe animals were domesticated through selective breeding over many generations to produce such traits as docility, Wayne said. However, we discovered that the theory of small numbers of animals carefully bred over many generations to adapt to humans could not nearly explain the enormous genetic diversity we found in horses.
If all domestic horses descended from a handful of female horses, we should have seen a limited diversity in mitochondrial DNA sequences, which are inherited from the mother, he said. Instead, we found many more sequences, and they were much more diverse than one would find in a single wild population. Many other animals were domesticated in one location, but this genetic diversity suggests that the domestication of horses must have been widespread. The theory that a few horses from one population were domesticated by a single clever culture does not fit.
In many parts of the world, people must have independently started to domesticate wild horses, said Carles Vila, a former UCLA postdoctoral scholar in Waynes laboratory who is an evolutionary geneticist at Swedens Uppsala University, and lead author of the stud
Contact: Stuart Wolpert
University of California - Los Angeles