A massive new genetic study proposes that humans originated near the border of modern-day South Africa and Namibia, a far more specific understanding than the vaguer picture of African origin that previously reigned.
Researchers from 11 countries collaborated on the study of more than 4 million genotypes, which was published today online in Science. By analyzing genetic sequences from 121 populations in Africa, 60 non-African populations and four African-American populations, they were able to trace Africans back to 14 ancestral clusters.
Charles Darwin first proposed an African origin of humans in his 1871 book The Descent of Man. It's now widely accepted that modern humans spent half of their 200,000 years on the planet in Africa, making it a key area of interest for geneticists, linguists and anthropologists alike.
The new study confirms prevailing assumptions that Africa is still home to the most genetic diversity.
Africa is currently has more than 2,000 ethno-linguistic groups, and the researchers were able to triangulate movement within and out of Africa by matching genetic and linguistic patterns. Among their other discoveries was a common ancestry between Pygmies and Khoisan speakers (those who use clicks in their language), and an average breakdown of the African-American genetic heritage in populations they studied (to about 71 percent western sub-Saharan African, 13 percent European and 8 percent other African groups). With a more detailed map of genes, researchers hope to be able to better understand health and disease in many of these populations.
"Our goal has been to do research that will benefit Africans," Sarah Tishkoff, a lead author of the study and a geneticist at the University of Pennsylvania School of Medicine, said in a statement. Future work, she noted will include "studies of genetic and environmental risk factors for disease and drug response."
Image of Tishkoff collecting genetic samples in Tanzania courtesy of Sarah Tishkoff