The project, the largest and most detailed analysis of African DNA ever carried out, found that the San bushmen are directly descended from the humans who gave rise to all other Africans and, eventually, the populations of the rest of the world.

Led by Dr Sarah Tishkoff, a geneticist at the University of Pennyslvania, and carried out by a team of African, US and European researchers, the study also found genetic similarities between Africans with shared languages, even though they lived thousands of kilometres apart, and was able to identify a number of adaptive genetic mutations, including one developed by groups of Africans when they started keeping cows.

‘These mutations were distinct from the mutation that arose in Europe,’ says Tishkoff. ‘It’s a very good example of genetic and cultural co-evolution because we have the development of a cultural innovation – the domestication of cattle – and the rise of a genetic mutation that played a role in the cultural development.’

The team hopes that their demonstration of the genetic diversity of African and African–American populations will convince medical researchers to use more ethnically diverse groups in future studies.  

‘Our goal has been to do research that will benefit Africans, both by learning more about their population history and by setting the stage for future genetic studies, including studies of genetic and environmental risk factors for disease and drug response,’ said Tishkoff.

July 2009