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Evolution in human DNA detected

Ian Sample

London: Scientists have spotted signs of recent evolution in the human genetic code, suggesting that diet and changes in habitat have had a lasting effect on our make-up.

In one of the first detailed scans of the entire human genome, researchers discovered more than 700 tweaks to genes they believe have arisen in the past 5,000 to 10,000 years, a period of time that saw humans spread north from equatorial regions and develop agriculture as a means of securing food.

As the fledgling human race encroached on new territories, shifts in climate and food saw that the best-adapted genes survived as less useful variations disappeared from the population.

Among the most striking changes are those in skin colour, with Europeans showing a surge in five genes linked to a lighter skin. At more northerly latitudes, where the sun's intensity is weaker, a lighter colour allows our skin to produce more vitamin D. While the genetic code of the Africans tested revealed a gene that makes our bodies retain salt that would be lost through sweating, the Europeans and Asians had a version that causes more salt to be released, possibly acting as a defence against salt-induced hypertension. —

© Guardian Newspapers Limited 2004

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