In the largest study ever of African genetic diversity, an international team of researchers has analyzed nuclear DNA collected over a decade from 113 populations of Africans from across the continent.

In a report published online in Science this week, the team has found that Africans are descended from 14 ancestral populations, which often correlate with language and cultural groups.

They found that all hunter-gatherers and pygmies in Africa today shared ancestors 35,000 years ago and that East Africa was the source of the great migration that populated the rest of the world.

They also found that African-American individuals, on average, have mixed ancestry from all over western Africa, which will make it difficult to trace roots to specific ethnic groups.

Via Science.