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Genomic Variation in Seven Khoe-San Groups Reveals Adaptation and Complex African History

Science  19 Oct 2012:
Vol. 338, Issue 6105, pp. 374-379
DOI: 10.1126/science.1227721

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Abstract

The history of click-speaking Khoe-San, and African populations in general, remains poorly understood. We genotyped ∼2.3 million single-nucleotide polymorphisms in 220 southern Africans and found that the Khoe-San diverged from other populations ≥100,000 years ago, but population structure within the Khoe-San dated back to about 35,000 years ago. Genetic variation in various sub-Saharan populations did not localize the origin of modern humans to a single geographic region within Africa; instead, it indicated a history of admixture and stratification. We found evidence of adaptation targeting muscle function and immune response; potential adaptive introgression of protection from ultraviolet light; and selection predating modern human diversification, involving skeletal and neurological development. These new findings illustrate the importance of African genomic diversity in understanding human evolutionary history.

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