Europeans come from three ancient populations

Thursday, 18 September 2014

An international team of scientists, including Ancient DNA researchers from the University of Adelaide, have found that modern Europeans can trace their ancestry to three ancient populations.

Published in the journal Nature today, the researchers compare ancient European hunter-gatherers and early farmers to present-day populations.

"Recent genetic studies we did at the University of Adelaide on ancient hunter-gatherers and early farmer remains suggested a massive expansion of people into Europe coinciding with the spread of farming," says Dr Wolfgang Haak, Research Fellow with the Australian Centre for Ancient DNA (ACAD).

"However, the relative proportions and distributions of the genetic components contributing to modern Europeans remained unclear. This study has added significantly to our knowledge of the genetic make-up of our European ancestors."

An international consortium led by researchers from the University of Tübingen in Germany and David Reich's group at the Harvard Medical School in the US analysed ancient human genomes from a 7,000-year-old early farmer from Stuttgart in Southern Germany, an 8,000-year-old hunter-gatherer from Luxembourg, and seven 8,000-year-old hunter-gatherers from Motala in Sweden.

They compared the ancient humans to present-day people, looking at the genetics of about 2,400 individuals from almost 200 diverse worldwide contemporary populations.

"The surprising finding was that present-day Europeans trace their ancestry back to three and not just two ancestral groups as previously thought," says ACAD Director and Australian Laureate Fellow Professor Alan Cooper who, together with Dr Haak, is co-author on the study.

The study found the great majority of present-day Europeans derive from at least three highly differentiated populations: the indigenous hunter-gatherers; the Middle Eastern farmers that migrated to Europe around 7,500 years ago; and a novel third is a more mysterious population that spanned North Eurasia and genetically connects Europeans and Native Americans.

"It seems clear now that the third group linking Europeans and Native Americans arrived in Central Europe after the early farmers," explains one of the lead investigators, Professor Johannes Krause from the University of Tübingen and director of the Max Planck Institute for History and Sciences in Jena, Germany. "We are however not sure yet when the Northern Eurasian component entered central Europe."

Using the large dataset of present-day and ancient human data, the researchers were able to calculate the proportion of the ancestral components in present-day Europeans.

They found that nearly all Europeans have ancestry from all three ancestral groups. Differences between them are due to the relative proportions of ancestry. Northern Europeans have more hunter-gatherer ancestry and Southern Europeans have more farmer ancestry. The Northern Eurasian ancestry is proportionally the smallest component everywhere in Europe, never more than twenty per cent.

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