A brief history of drinking milk: what our genes can tell us

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Jim Cummins/CORBIS

Jim Cummins/CORBIS

Europeans’ ability to digest dairy after infancy evolved just 7,500 years ago, spreading out from central Europe — not northern Europe, as previously believed — across the continent and into western Asia.

That’s the claim of a new study published today in the journal PLoS Computational Biology. Most adults in the world can’t produce the enzyme lactase, and that leaves them unable to digest the milk sugar lactose (a condition you’ve no doubt heard of: lactose intolerance). But most adults of European ancestry do produce lactase — and that enzyme production seems to be linked to one single genetic variant, which, the study authors write, must have been very heavily favored by recent natural selection. The researchers use a computer model with genetic data and archaeological records to simulate the simultaneous evolution of humans’ dairy farming and milk consumption. They determine that dairy farming spread along the same routes as the genetic trait, starting in the central Balkans and elsewhere in central Europe. It would appear, in fact, that dairy consumption gave early European agriculturalists a massive survival advantage over non-dairy consumers, since the lactase trait has become almost universal among Europeans in a scant 7,500 years — a very short time indeed on the evolutionary scale.

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