Research Article

The Genetic Structure and History of Africans and African Americans

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Science  22 May 2009:
Vol. 324, Issue 5930, pp. 1035-1044
DOI: 10.1126/science.1172257

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Africa is the source of all modern humans, but characterization of genetic variation and of relationships among populations across the continent has been enigmatic. We studied 121 African populations, four African American populations, and 60 non-African populations for patterns of variation at 1327 nuclear microsatellite and insertion/deletion markers. We identified 14 ancestral population clusters in Africa that correlate with self-described ethnicity and shared cultural and/or linguistic properties. We observed high levels of mixed ancestry in most populations, reflecting historical migration events across the continent. Our data also provide evidence for shared ancestry among geographically diverse hunter-gatherer populations (Khoesan speakers and Pygmies). The ancestry of African Americans is predominantly from Niger-Kordofanian (~71%), European (~13%), and other African (~8%) populations, although admixture levels varied considerably among individuals. This study helps tease apart the complex evolutionary history of Africans and African Americans, aiding both anthropological and genetic epidemiologic studies.

  • Present address: Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, 24306 Plön, Germany.

  • These authors contributed equally to this work.

  • § These authors contributed equally to this work.

  • || Present address: Department of Internal Medicine, Ohio State University, Columbus, OH 43210, USA.

  • Present address: Office of Research and Development, National Center for Computational Toxicology, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.

  • # Present address: College of Education, University of Maryland, College Park, MD 20742, USA.

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