It was only when early humans gave up hunter-gathering and switched to farming about 5,500 years ago that white skin began to be favoured, say the researchers.
This is because farmed food was deficient in vitamin D, a vital nutrient. Humans can make this in their skin when exposed to sunlight, but dark skin is much less efficient at it.
In places such as northern Europe, where sunlight levels are low, the ability to make vitamin D more efficiently could have been crucial to survival.
Johan Moan, of the Institute of Physics at the University of Oslo, said in a research paper: “In England, from 5,500-5,200 years ago the food changed rapidly away from fish as an important food source. This led to a rapid development of ... light skin.”
http://www.timesonline.co.uk/tol/news/s ... 814896.ece
I'm surprised that it doesn't take a long time to develop a skin colour.
The global warming has one advantage: soon the Earth will be dominated by blacks.








