Frozen Scythian stallions unravel mysteries of horse domestication

Sebastien Lepetz/Museum National d’Histoire Naturelle, Paris

Frozen Scythian stallions unravel mysteries of horse domestication

First tamed by humans about 6000 years ago, horses today bear distinct marks of their early domestication. Thousands of years of inbreeding, for example, have littered horse genomes with detrimental DNA. And because modern stallions all share a similar Y chromosome, early equestrians must have studded their herds with just a few males. Or so researchers thought. Now, by sequencing the genomes of 11 frozen stallions buried 2300 years ago in a Scythian prince’s tomb in the permafrost of Kazakhstan (above), researchers have discovered that the first horses came from plentiful male stock. What’s more, detrimental DNA had not yet begun to accumulate by the time these Eurasian nomads harnessed horsepower to conquer neighboring peoples. The new work also shows that wild horses continued to interbreed with domestic ones throughout this time period, evolutionary geneticists reported last week at the Biology of Genomes meeting in Cold Spring Harbor, New York. The scientists call their work a “proof of principle” in their push to sequence ancient DNA from 100 horses of other ancient civilizations—such as the Roman Empire—to fill out our horse-human history.