In the most comprehensive study of African genetic diversity to date, a team of international scientists, led by Dr Sarah Tishkoff from the University of Pennsylvania in Philadelphia, US, has revealed Africa to be the most genetically diverse continent on Earth. The findings could be used as a foundation to study genetic risk factors for diseases and the genetic basis of the differences in drug responses in these populations.
The research, published in the journal Science, used data from almost 4,000 people to reveal 14 ancestral populations from which modern Africans are descended. Their results correlated well with differences in culture and language, and they were able map the migration of populations across the continent.
Dr Tishkoff said 'we also think that non-Africans originate from a small founding population that probably migrated out of East Africa. In fact, our study shows that the source of the migration out of Africa was centred on the Dead Sea'.
One of the researchers, Muntaser Ibrahim, from the University of Khartoum, Sudan, said 'This is a spectacular insight into the history of African populations and therefore the history of mankind'.
Genetic studies in Africa have been severely limited, largely owing to the logistics involved in sample collection and storage, travel to remote villages, and gaining ethics approval in each country. This is the first time such a comprehensive study has been undertaken.
The researchers have, over the last ten years, traversed Africa by four-wheel drive collecting blood samples from people in 121 African populations. The study also included four African-American and 60 non-African populations. The DNA from these individuals was then screened for 1,327 markers that cover highly variable DNA markers of the type used in forensic studies. Scientists from other teams have previously screened individuals from mostly non-African populations for the same set of markers.
Dr Tishkoff said 'by using the same set of markers we have this wonderful comparative data set, and we can look at African genetic diversity in the context of the rest of the globe'. The results of the genetic scans were analysed using a program that separates individuals into groups depending on their genetic similarity across these markers.
'Our goal has been to do research that will benefit Africans. I hope this will set the stage for future genomics research there, and future biomedical research' Dr Tishkoff said.