http://www.nature.com/news/2007/070226/full/070226-4.html Published online: 26 February 2007; | doi:10.1038/news070226-4
Ancient DNA solves milk mystery
Analysis of fossilized bones suggests milk-drinking mutations emerged after dairy herding.

Erika Check

When did ancient populations learn that drinking milk 'does a body good'? A team of scientists in Germany has tried to answer this question by studying ancient DNA extracted from skeletons thousands of years old.

Many adult humans can drink cow's milk - a rare feat among mammals, which usually lose the ability to digest the sugar in milk after they are weaned. Scientists have found the genetic mutations that allow many Europeans and some Africans to digest milk (see 'Human evolution: How Africa learned to love the cow'). Geneticists have estimated that these mutations first spread 3,000 to 7,000 years ago in eastern Africa, and slightly earlier than that in Europe.

But some researchers have posed a 'chicken-and-egg' question about milk drinking: was dairy herding adopted only by those populations who could already drink milk? Or did the invention of dairy herding favour those people who had the mutation, so that the mutation quickly spread throughout the population?

Joachim Burger of the University of Mainz, Germany, and colleagues worked with Mark Thomas of University College London, UK, to address this riddle by studying DNA from skeletons scattered throughout Europe. The team examined ten skeletons ranging in age from 3,800 to nearly 6,000 years old. The skeletons were discovered at archaeological sites in Germany, Hungary, Poland and Lithuania.