Three African populations that rely mainly on hunting and gathering possess a trove of previously unrecorded genetic diversity.
Sarah Tishkoff at the University of Pennsylvania in Philadelphia and her team sequenced the full genomes of five individuals from each of three populations: Cameroonian Pygmies, and the Hadza (pictured) and Sandawe people from Tanzania. The researchers' trawl uncovered 13.4 million variants — more than 3 million of which have never been seen before.
Genes involved in immunity, metabolism, taste, smell and reproduction seem to have evolved since the different populations split — a sign of adaptation to local environments. In the Pygmies, recent changes in genes involved in the function of the pituitary gland, which secretes growth and other hormones, could explain their short stature. All the hunter-gatherers sampled showed signatures of gene flow from now-extinct human species. This has been seen before mainly in non-African populations, supporting the idea that breeding between various human species occurred regularly.
Cell http://dx.doi.org/10.1016/j.cell.2012.07.009 (2012)
For a longer story on this research, see go.nature.com/ss7rzr