By Ann Gibbons

Republication from www.sciencemag

The Bronze Age came to Europe and Asia 5000 years ago, leaving a trail of metal tools, axes, and jewelry that stretches from Siberia to Scandinavia. But was this powerful new technology an idea that spread from the Middle East to European and Asian people, or was it brought in by foreigners? Two of the largest studies of ancient DNA from Bronze Age and Iron Age people have now found that outsiders deserve the credit: Nomadic herders from the steppes of today’s Russia and Ukraine brought their culture and, possibly, languages with them—and made a relatively recent and lasting imprint on the genetic makeup of Europeans and Asians.

In the studies, published online today in Nature, two rival teams of geneticists analyzed the DNA from 170 individuals who lived at key archaeological sites in Europe and Asia 5000 to 3000 years ago. Both teams found strong evidence that a wave of nomadic herders known as the Yamnaya from the Pontic-Caspian, a vast steppeland stretching from the northern shores of the Black Sea and as far east as the Caspian Sea, swept into Europe sometime between 5000 and 4800 years ago; along the way, they may have brought with them Proto-Indo-European, the mysterious ancestral tongue from which all of today’s 400 Indo-European languages spring. These herders interbred with local farmers and created the Corded Ware culture of central Europe, named for the twisted cord imprint on its pottery. Their genes were passed down to northern and central Europeans living today, as one of the teams posted on a preprint server earlier this year and published today.

But in a new twist, one of the studies also found that the Yamnaya headed east from their homeland in the Eurasian steppelands, moving all the way to the Altai Mountains of Siberia, where they replaced local hunter-gatherers. This means that this distinctive culture of pastoralists, who had ox-driven wagons with wheels and whose warriors rode horses, dominated much of Eurasia, from north-central Europe to central Siberia and northern Mongolia. They persisted there until as recently as 2000 years ago. “Now we see the Yamnaya is not only spreading north into Europe; they’re also spreading east, crossing the Urals, getting all the way into central Asia, all the way into the Altai, between Mongolia, China, and Siberia,” says evolutionary biologist Eske Willerslev of the University of Copenhagen, author of one study.

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