New branch added to European family tree. Genetic analysis reveals present-day Europeans descended from at least 3, not 2, groups of ancient humans

Stephanie Dutchen, EurekAlert, 17-09-2014

The setting: Europe, about 7,500 years ago. Agriculture was sweeping in from the Near East, bringing early farmers into contact with hunter-gatherers who had already been living in Europe for tens of thousands of years. Genetic and archaeological research in the last 10 years has revealed that almost all present-day Europeans descend from the mixing of these two ancient populations. But it turns out that’s not the full story.

Researchers at Harvard Medical School and the University of Tübingen in Germany have now documented a genetic contribution from a third ancestor: Ancient North Eurasians. This group appears to have contributed DNA to present-day Europeans as well as to the people who travelled across the Bering Strait into the Americas more than 15,000 years ago. “Prior to this paper, the models we had for European ancestry were two-way mixtures. We show that there are three groups,” said David Reich, professor of genetics at HMS and co-senior author of the study. “This also explains the recently discovered genetic connection between Europeans and Native Americans,” Reich added. “The same Ancient North Eurasian group contributed to both of them.” The research team also discovered that ancient Near Eastern farmers and their European descendants can trace much of their ancestry to a previously unknown, even older lineage called the Basal Eurasians.

To probe the ongoing mystery of Europeans’ heritage and their relationships to the rest of the world, the international research team—including co-senior author Johannes Krause, professor of archaeo- and paleogenetics at the University of Tübingen and co-director of the new Max Planck Institute for History and the Sciences in Jena, Germany—collected and sequenced the DNA of more than 2,300 present-day people from around the world and of nine ancient humans from Sweden, Luxembourg and Germany. The ancient bones came from eight hunter-gatherers who lived about 8,000 years ago, before the arrival of farming, and one farmer from about 7,000 years ago. The researchers also incorporated into their study genetic sequences previously gathered from ancient humans of the same time period, including early farmers such as Ötzi “the Iceman.”

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