Wednesday, September 2, 2009

White Europeans 'only evolved 5,500 years ago after food habits changed'



People in England may have only developed pale skin within the last 5,500 years, according to new research. Scientists believe that a sudden change in the diet around that time from hunter-gathering to farming may have led to a dramatic change in skin tone to make up for a lack of vitamin D. Farmed food is lacking in vitamin D and while humans can produce it when exposed to the ultraviolet light in sunlight darker skin is far less efficient at it.

People with pale skin may be descended from Europeans who dramatically changed their diets after switching from hunter-gathering to farming. Scientists at the University of Oslo believe this change in diet may have led to our dark-skinned ancestors evolving paler skin to overcome this problem.

The link between skin colour and Vitamin D from sunlight has been suggested before. It had previously been believed that our ancestors’ skin had gradually lightened to generate more Vitamin D the further north they moved away from the equator to places where there was less sunlight. Now scientists believe that the change in their diet away from foods rich in Vitamin D also played a major factor in the skin lightening in colour. And the particularly pale skins of people in Scandinavia may have evolved to maximise the amount of Vitamin D that could be produced, the research suggests. [There is some very pale skin in Ireland too. I have inherited it myself]

If the theory is correct it would mean that until this period in history, the ancient inhabitants of Britain and Scandinavia - our ancestors - would have had a dark skin tone.

Johan Moan, of the university's Institute of Physics, 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.’ The research paper, written with Richard Setlow, a biophysicist at Brookhaven National Laboratory in New York state, states : ‘Cold climates and high latitudes would speed up the need for skin lightening. ‘Agricultural food was an insufficient source of vitamin D, and solar radiation was too low to produce enough vitamin D in dark skin.’

Children with fair skins are able to get their daily dose of Vitamin D with just 10 to 20 minutes in the sun. But research has shown that sun-protective skin pigments in black children means that it takes up four times as long for the skin to produce enough of the vitamin. Milk and a few other foods such as fatty fish are fortified with vitamin D but most people get very little through their diets.

A lack of Vitamin D has been linked with cancers, bone problems, type 1 diabetes, and even multiple sclerosis. One recent study in the U.S found that nearly half of African American women of childbearing age may be deficient in vitamin D.


http://www.dailymail.co.uk/sciencetech/article-1210056/White-Europeans-evolved-5-500-years-ago-food-habits-changed.html

1 comment:

Malcolm said...

As a zoology graduate, I have my doubts. Probably a change of diet had some effect, but it takes would be expected to take a long time for such an evolutionary change to take place. Certainly, by the time recorded history opens about 4,000 years ago, pale skin (admittedly olive) was universally established in the Middle East. Also, it must be remembered that agriculture spread northwards into the Boreal regions, and the areas where the skin is palest are the areas where agriculture was last to develop. Furthermore, agriculture appears to have been developed independently in the Americas, yet the groups where it has existed longest are not significantly lighter than their hunter gatherer neighbours.