14 DAY TRIAL // We migrated from Africa about 100,000 years ago and, since then, we have colonized the whole Earth, adapting to new environments and diets. It is clear that this accelerated an evolution in our physical traits, in the genes connected to skin color or stature, as means of adaptation to novel habitats.
A new research published in the journal "Nature Genetics," by a French-Spanish team, has detected no less then 582 genes that have experienced a rapid evolution amongst human populations in the past 60,000 years, including genes involved in protection from obesity, diabetes, hypertension, and other conditions.
Researchers led by population geneticist Lluis Quintana-Murci of the Pasteur Institute and Centre National de le Recherche Scientifique, in Paris, investigated DNA of 210 persons included in the Phase II of the International HapMap Project, aimed to detect human mutations behind genetic diseases. Variations in around 2.8 million single nucleotide polymorphisms (SNPs) were investigated in samples coming from European, African, and Asian individuals. The team detected 15,259 variations that caused the mutation of the encoded protein.
Statistics revealed that some mutations had such high frequencies that they should have boosted survival and reproductive success, being clearly positively selected.
"These mutations varied tremendously between populations, which counters a popular view that many of the differences between populations arose by chance or were genetic variants that hitchhiked along with other genes that improved reproductive success," said biological anthropologist Henry Harpending of the University of Utah, Salt Lake City, co-author of a similar research.
Of the 582 genes experiencing such powerful positive natural selection, the team could clearly assign only 50 to their function. They were all connected to diseases and changes in diet or environment, like genes controlling insulin synthesis, sugars, starches, ethanol (alcohol) and zinc metabolism, fat transportation, immune reaction to pathogens, and DNA repair and replication.
"New mutations that 'protect' people from diabetes and obesity have been selected probably because they significantly improved peoples' ability to handle agricultural diets. For example, new dependence on a few cereal grains required efficient digestion of starches," said biological anthropologist John Hawks of the University of Wisconsin, Madison, co-author to Harpending's studies.