A new paper reports that studies of DNA from 101 Bronze Age skeletons shows that Europeans came from nomadic tribes who invaded during the Bronze Age.
Morten E. Allentoftet al. Population genomics of Bronze Age Eurasia. Nature, 2015; 522 (7555): 167 DOI:10.1038/nature14507
Abstract: The Bronze Age of Eurasia (around 3000–1000 BC) was a period of major cultural changes. However, there is debate about whether these changes resulted from the circulation of ideas or from human migrations, potentially also facilitating the spread of languages and certain phenotypic traits. We investigated this by using new, improved methods to sequence low-coverage genomes from 101 ancient humans from across Eurasia. We show that the Bronze Age was a highly dynamic period involving large-scale population migrations and replacements, responsible for shaping major parts of present-day demographic structure in both Europe and Asia. Our findings are consistent with the hypothesized spread of Indo-European languages during the Early Bronze Age. We also demonstrate that light skin pigmentation in Europeans was already present at high frequency in the Bronze Age, but not lactose tolerance, indicating a more recent onset of positive selection on lactose tolerance than previously thought.
Nature News reports on the paper:
A team led by palaeogenomicists Morten Allentoft and Eske Willerslev at the Natural History Museum of Denmark in Copenhagen has used these advances to sequence the genomes of 101 people who lived across Eurasia between about 3000 bc and ad 700 (ref. 2). “We could have stopped at 80,” says Allentoft. But “we thought, ‘Why the hell not? Let’s go above 100.’”
The sequences allowed the team to tackle questions that have vexed archaeologists for decades, says Allentoft. For example, researchers have disagreed over whether the cultural changes of the Bronze Age were the result of migration or simply the spread of ideas. Allentoft and his colleagues found evidence for migration, in the form of a massive shift in the genetic make-up of northern and central Europeans at the start of the Bronze Age. Before 3000 bc, their genomes resembled those of early farmers from the Middle East and even earlier European hunter-gatherers. By 2000 bc, their genomes looked more like those of people from the Yamnaya culture, which arose on the steppe around 2900 bc.
The findings echo those of a team that sequenced 69 ancient Europeans. Both groups speculate that the Yamnaya migration was at least partly responsible for the spread of the Indo-European languages into Western Europe.
Allentoft’s team found genetic traces of the Yamnaya in people who lived near the Altai Mountains in central Russia from 2900 bc to 2500 bc, potentially explaining why Indo-European languages are spoken so far into Asia. “It’s pretty clear that these eastern cultures in the Bronze Age are linked to the Yamnaya,” says Pontus Skoglund, a population geneticist at Harvard Medical School in Boston, Massachusetts. But he is not yet convinced that the culture’s wanderings explain the origins of all Indo-European languages.
So it would seem that hunter-gatherers mixed with farmers from the east who spread across Europe about 9,000 years ago. They formed the first agricultural settlements. Then came the invasion of the nomadic Yamnaya culture around 5,000 years ago. The Yamnayans were much more individualistic than the peoples they replaced and gave rise to the prominence of the nuclear family and the development of large family holdings of cleared lands, rather than the clusters of people in village settlements. They came on horses and brought livestock. But by about 4,000 years ago they too were overrun by the warlike Sintashta.
The genetic evidence of the spread of the Yamnaya culture, first westwards and then eastwards, suggests that proto-Indo-European starts here. This picture is not inconsistent with the Eurasian region being the origin of proto-Indo-European. But the genetic picture tends to support the “steppe hypothesis” rather than the “Anatolian hypothesis”.
Nature News: …… Scholars have long recognized an Indo-European language group that includes Germanic, Slavic and Romance languages as well as classical Sanskrit and other languages of the south Asian subcontinent. Yet the origins of this family of tongues are mired in controversy.
……. Some researchers hold that an early Indo-European language was spread by Middle Eastern farmers around 8,000–9,500 years ago (see ‘Steppe in time’). This ‘Anatolian hypothesis’ is supported by well-documented migrations into Europe, where agriculturalists replaced or interbred with the existing hunter-gatherers. In 2012, a team led by evolutionary biologist Quentin Atkinson of the University of Auckland in New Zealand produced a family tree of Indo-European tongues that also pointed to an Anatolian origin more than 8,000 years ago.
A competing theory posits that the languages emerged on the Eurasian steppe some 5,000–6,000 years ago, when the domestication of horses and invention of wheeled transport would have allowed herders there to rapidly expand their range. Proponents of the ‘steppe hypothesis’ note that linguistic reconstructions of a proto-Indo-European tongue include words associated with wheeled vehicles, which were not invented until long after Middle Eastern farmers had reached Europe. “Most linguists have signed up to the steppe hypothesis,” says Paul Heggarty, a linguist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.