New DNA evidence suggests that herders from the grasslands of today's Russia and Ukraine carried the roots of modern European languages across the continent some 4,500 years ago.

The introduction of farming has often been described as the pivotal event in European prehistory. The new study, published Monday in the journal Nature, suggests that instead of one mass migration of farmers, as long thought, there were two: first an influx from Anatolia, a region of today's Turkey, and then a second wave of people moving into central Europe from the steppes of modern-day Russia, four millennia later, who would have brought with them the Indo-European languages that became English and many other modern European languages.

"First there are early hunter-gatherers, then come farmers, then farmers mix with hunter-gatherers—then comes a new population from the east, which is the major migration," says Iosif Lazaridis, a geneticist at Harvard Medical School and co-author of the paper.

Evidence of this second mass migration came to light while Lazaridis and colleagues were working to reconstruct the origins of modern Europeans, using DNA recovered from the bones of 69 ancient inhabitants of the continent. The specimens, which ranged from 3,000 to 8,000 years old, were compared to each other and to modern European populations.

As expected, the researchers found traces of ancient hunter-gatherers and the first Neolithic farmers. But there was an unexpected wrinkle: a massive population movement coming from the plains and grasslands of Eurasia, where Russia and Ukraine are today, beginning around 4,500 years ago.

Waves of Migration

Dominated by small bands of hunter-gatherers for millennia, the continent was first reshaped around 8,000 years ago in what archaeologists call the Neolithic Revolution. Farmers from Anatolia moved north, bringing new technology and lifestyles into Europe and setting the stage for our modern, settled existence.

A crucial clue in detecting a second wave of movement several thousand years later was the similarity between DNA recovered from 5,000-year-old bones found north of the Black Sea, belonging to people archaeologists call the Yamnaya, and the remains of four people who lived and died near Leipzig, in central Germany, about 4,500 years ago. The German bodies were part of the Corded Ware culture, named after a distinct style of pottery decoration common across most of northern Europe at the time.

The Yamnaya and Corded Ware people were separated by five centuries and a thousand miles, but they shared at least 75 percent of their ancestry—and perhaps as much as 100 percent. "You can see a direct genetic relationship between these two populations," says David Anthony, an archaeologist at Hartwick College, in Oneonta, New York, and a co-author of the study. "They're close cousins, at least."

The DNA from the Corded Ware bones looks very little like that of farmers living in Germany a thousand years earlier, more evidence for a dramatic, even invasive, influx from the east. "It's almost a total replacement event," says Lazaridis.

View Images A young woman buried in Germany more than 4,000 years ago was related to cattle-herding migrants from the east. Photograph by LDA Sachsen-Anhalt

Bones just a few centuries older found in the same region of Germany had a totally different genetic signature. In fact, the evidence suggests it took just a few generations for the cattle herders from the steppes to dominate central and northern Europe's genetic and physical landscape.

"From a conservative archaeological point of view, I would not have predicted people from the steppe would have migrated from the mouth of the Danube to Denmark within a century or two," says Anthony. "This is a big surprise."

Roots of Europe's Languages

The genetic evidence of a massive migration from the steppes is rekindling an old debate among linguists and archaeologists about the origins of Indo-European languages. These include more than 400 tongues, from modern ones like English, Greek, Albanian, and Polish to ancient languages like Latin, Hittite, and Sanskrit.

For decades, linguists have debated where proto-Indo-European, the mother of all Indo-European languages, was first spoken. Advocates of the "Anatolian hypothesis" argue that the first Indo-European speakers were farmers living in what is now Turkey ten thousand or more years ago, who brought the language with them when they arrived in Europe around 6,000 B.C.

A competing theory, the so-called "steppe hypothesis," puts proto-Indo-European language on the open plains and grasslands north of the Black and Caspian Seas, where the arrival of the wheel "revolutionized steppe economies," says Anthony. Proponents of this idea note that many Indo-European languages share words for things like axles, harness poles, and the wheel, which were invented long after the Neolithic Revolution began in Europe.

But with nothing conclusive to corroborate either theory, the debate has been deadlocked for decades.

The study's results may tip the balance, the researchers think, by providing the migration necessary for the steppe hypothesis to hold water.

There's more work to be done. The genetic and linguistic data support the idea that Indo-European entered Europe via the steppes around 4,500 years ago, but "it's still not clear to me where the oldest branches" of the language come from, says Carles Lalueza-Fox, a geneticist at the University of Barcelona. Indo-European might have originated elsewhere, with the steppe route being just one of several ways that a root tongue made it to southern Europe, Iran, and India, Lalueza-Fox says.