For Release: May 1, 2009
Contact: dms.communications@dartmouth.edu, 603-650-1492
Large-scale African genetics study finds surprising diversity, few ancestral groups
Dr. Jason Moore
Hanover, N.H.—A Dartmouth Medical School researcher is part of an international team that has determined that Africans are descended from 14 ancestral populations. The study, published April 30 online in Science Express, demonstrates startling diversity on the continent, considered the source of modern humans.
"This is one of the largest-ever population-based genetic studies in Africa. I can't stress enough the historical importance of this work," says Dr. Jason Moore, professor of genetics and of community and family medicine at Dartmouth Medical School, and an author on the paper. "It will be cited for many years to come and provides one of the best examples of how genetics can be used to understand the origins of all humans."
They study demonstrates shared ancestry among geographically diverse groups and traces the origins of Africans and African Americans. Considered the largest-ever study of African genetic data--more than four million genotypes--it provides a library of new information on the continent.
A team of 25 collaborators, with lead author Dr. Sarah Tishkoff of the departments Genetics and Biology at the University of Pennsylvania, analyzed samples from 121 African populations, 4 African-American populations, and 60 non-African populations, representing more than 3,000 individuals.
The study, in part, used data that had been gathered over the last 10 years by Moore and co-author Scott Williams, with the Center for Human Genetics Research at Vanderbilt University, for one of the largest population-based genetic studies in Africa (the Hypertension and Arterial Thrombosis (HeART) study) to identify genetic risk factors for common human diseases.
This [is the] first comprehensive analysis of the genetic structure and history of Africans and African Americans.
—Dr. Jason Moore
"Our samples, along with others from around Africa and elsewhere, were used by Dr. Tishkoff and the co-authors to provide this first comprehensive analysis of the genetic structure and history of Africans and African Americans," says Moore.
The study reveals that Africans originated from 14 ancestral population clusters that correlate with ethnicity and shared cultural and/or linguistic elements and that there is more genetic diversity in Africa than anywhere else on earth.
The ancestral origin of humans was probably located in southern Africa, near the South Africa-Namibian border and the exit point of modern humans out of Africa was near the middle of the Red Sea in East Africa, the scientists determined. They also provide evidence for ancient common ancestry of geographically diverse hunter-gatherer populations in Africa, including Pygmies from central Africa and click-speaking populations from southern and eastern Africa.
The paper states, "We observe high levels of mixed ancestry in most populations, reflecting historic 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."
The team includes individuals from the Max Planck Institute of Evolutionary Biology in Germany; the University of California, Los Angeles; the Universita di Ferrara, Italy; Musee de l'Homme, Paris; Ohio State University; Ministere de la Recherche Scientifique et de l'Innovation, Cameroon; University of Bamako, Mali; University of Khartoum, Sudan; University of Stellenbosch, South Africa; Muhimbili University of Health and Allied Sciences, Tanzania; U.S. Environmental Protection Agency; Center for Biotechnology Research and Development, Kenya; University of Maryland; National Cancer Institute; International Biomedical Research in Africa, Nigeria; and the Marshfield Clinic Research Foundation, Wisconsin.
-DMS-
