Thursday, September 3, 2009

Milk, genes and ethnic differences

Somewhat less than 40% of people in the world retain the ability to digest lactose after childhood. The numbers are often given as close to 0% of Native Americans, 5% of Asians, 25% of African and Caribbean peoples, 50% of Mediterranean peoples and 90% of northern Europeans. Sweden has one of the world's highest percentages of lactase tolerant people. There's been a lot of research over the past decade looking at the genetic mutation that allows this subset of humanity to stay milk drinkers into adulthood. Now a group at University College London has shown that the mutation actually appeared about 7,500 years ago in dairy farmers who lived in a region between the central Balkans and central Europe, in what was known as the Funnel Beaker culture. The researchers used a computer to model the spread of lactase persistence, dairy farming, other food gathering practices and genes in Europe. Today, the highest proportion of people with lactase persistence live in Northwest Europe, especially the Netherlands, Ireland and Scandinavia. But the computer model suggests that dairy farmers carrying this gene variant probably originated in central Europe and then spread more widely and rapidly than non-dairying groups. Author Mark Thomas of University College London's dept of Genetics, Evolution and Environment says: "In Europe, a single genetic strongly associated with lactase persistence and appears to have given people with it a big survival advantage." The European mutation is different from several lactase persistence genes associated with small populations of African peoples who historically have been cattle herders.


The Origins of Lactase Persistence in Europe

Lactase persistence spread with Neolithic Linearbandkeramik

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