The ability to digest the milk sugar lactose first evolved in dairy farming communities in central Europe, not in more northern groups as was previously thought, finds a new study led by UCL (University College London) scientists published in the journal PLoS Computational Biology. The genetic change that enabled early Europeans to drink milk without getting sick has been mapped to dairying farmers who lived around 7,500 years ago in a region between the central Balkans and central Europe. Previously, it was thought that natural selection favoured milk drinkers only in more northern regions because of their greater need for vitamin D in their diet. People living in most parts of the world make vitamin D when sunlight hits the skin, but in northern latitudes there isn’t enough sunlight to do this for most of the year.
In the collaborative study, the team used a computer simulation model to explore the spread of lactase persistence, dairy farming, other food gathering practices and genes in Europe. The model integrated genetic and archaeological data using newly developed statistical approaches.
Professor Mark Thomas, UCL Genetics, Evolution and Environment, says: “Most adults worldwide do not produce the enzyme lactase and so are unable to digest the milk sugar lactose. However, most Europeans continue to produce lactase throughout their life, a characteristic known as lactase persistence. In Europe, a single genetic change (13,910*T) is strongly associated with lactase persistence and appears to have given people with it a big survival advantage. Since adult consumption of fresh milk was only possible after the domestication of animals, it is likely that lactase persistence co-evolved with the cultural practice of dairying, although it was not known when it first arose in Europe or what factors drove its rapid spread.