Why Do Europeans Have White Skin?

A genetic study has concluded that for the majority of time humans have been in Europe, they had dark skin. The genes that make for light skin are a fairly recent arrival. Like the capacity to digest milk as an adult, pale skin was sufficiently advantageous at high latitudes that it spread rapidly through the population. The 1000 Genomes Project is looking for examples of such mutations by comparing the genomes of modern individuals from specific regions in Europe with 83 samples taken from 7 ancient European cultures. Harvard University's Dr. Iain Mathieson has found 5 features whose spread indicates a strong selection advantage. Previous studies have identified 1 of these 5 traits: the ability to digest lactose in adulthood. Although not exactly universal, most people of European decent are able to tolerate lactose. In fact, dairy makes up a major part of many European diets. 8,000 years ago, this was not the case. Mathieson expanded on the previous work, showing that the ability to digest lactose as an adult occurred after the advent of farming. Two waves of farmers settled Europe 7,800 and 4,800 years ago, but it was only 500 years later that the gene for lactose tolerance became widespread. As I'm sure is no surprise, the first early humans to leave Africa were black. Mathieson found that more than 30,000 years later hunter-gatherers in what is now Spain, Luxumberg and Hungary had dark-skinned versions of the two genes more strongly associated with skin color. The oldest pale versions of SLC24A5 and SLC45A2 genes discovered were found at Motala in southern Sweden 7,700 years ago. The genes for blue eyes and blonde hair were also found in bodies at this site. The light SLC24A5 gene spread through Europe with farmers that came from the east while the light SLC45A2 only became common 5,800 years ago. Mathieson was shocked to not find a strong selection for immunity to transmissible disease with the spread of agriculture but he did identify patterns in height, with shortness being favoured in the first farmers on the Iberian Peninsula, while genes associated with tallness took over 5,000 years ago.