Europeans descended from brown-eyed farmers and blue-eyed hunter-gatherers

Europeans descended from brown-eyed farmers and blue-eyed hunter-gatherers

The newly sequenced genomes of 10 ancient Europeans suggest that modern Europeans descend from blue-eyed hunter-gatherers who arrived from Africa more than 40,000 years ago, brown-eyed Middle Eastern farmers who migrated west 10,000 years ago, and a mysterious population who spanned northern Europe and Siberia.

The genomes of 9 individuals – one man from Luxembourg, one woman from Germany and seven individuals from Sweden – dating back 7,500 – 8,000 years were analysed by Johannes Krause of the University of Tübingen, Germany, and David Reich of Harvard Medical School in Boston, Massachusetts.

A second team, led by Carles Lalueza-Fox at the University Pompea Fabra in Barcelona, Spain, has sequenced the genome of one of two 7,000-year-old males previously discovered in northwest Spain, but initial findings suggested that they bore little genetic relationship to modern Spaniards.

The individuals from Luxembourg and Spain were dark-skinned with blue eyes and belonged to groups known to be hunter-gatherers.  The German woman had lighter skin with brown eyes and was related to Middle Eastern groups known to have developed farming.

Both the Luxembourg hunter-gatherer and the German farmer had copies of a gene that breaks down starches in saliva, thought to be an adaptation to a grain-based agricultural diet, but neither had the ability to digest the sugar lactose found in milk, a later trait emerging in the Middle East after the domestication of cattle.

While the study supports previous theories that modern Europeans mostly descend from Middle Eastern farmers who interbred with or displaced indigenous hunter-gatherers, the surprise finding is the genetic contribution of a third population of ancient northern Eurasians.  This group may have lived at high latitudes between Europe and Siberia until a few thousand years ago.  Their traces were also found in the genome of a 24,000 year old Siberian boy who was also closely related to modern Native Americans.

A comparison of the ancient and modern DNA samples shows how today’s European populations are varying mixtures of the three ancient groups.  For example, Scots and Estonians have more of the northern Eurasian ancestry than any other modern European populations, whereas Sardinians are the most closely related to the Middle Eastern farmers.

However, Professor Lalueza-Fox rightly cautions against jumping to too many conclusions about the peopling of Europe from just a few ancient genomes: “There’s lots of different migrations and movements,” he said. “There’s going to be plenty of room for investigation in the next few years.”

Source: Nature

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Posted by Abroad in the Yard on Friday, 14 August 2015