Most of the mutations resulted from dramatic population booms, the report suggests.

As populations expanded, the number of mutations increased, boosting the chances for beneficial genetic variants that can improve survival.

Lead researcher Henry Harpending, of the University of Utah, says he doesn’t know the identity of most of the genes in which the mutations occurred.

But he says quite a few appear to be responses to changes in diet and a new wave of virulent diseases that swept through human populations as they began farming.

Some examples include mutations that allow adults to digest starch, fatty acids and lactose in milk, including mutations that arose among Europeans.

Other elements of genetic change improved the resistance to diseases, such as malaria, AIDS and yellow fever in Africans.

Several genes related to the production of human sperm also have mutated over the past 10,000 years.

Harpending says his study has found that even though world travelers and migrants have interbred far from where they were born, most humans on different continents are becoming more different, rather than blending together into one genetically homogeneous race.

Image: Mads Abildgaard         Digg This