Africans are the most diverse people on Earth, suggests DNA analysis

May 1st, 2009 - 12:40 pm ICT by ANI  

London, May 1 (ANI): In a new DNA based study, an international team of scientists has suggested that the Africans are the most diverse people on Earth, as they originated from 14 ancestral groups that mixed freely with each other to create the distinct populations that exist today.

According to a report in Nature News, the study, which included a wide-ranging DNA analysis of Africans, revealed a detailed picture of the continent’s rich genetic diversity, as well as traces of the evolutionary history and migrations of various groups.

Modern humans first evolved in Africa about 200,000 years ago, before migrating to other parts of the world. Today, Africa has more than 2,000 groups with different ethnicities and languages.

But, genetic studies of Africans have been limited to small numbers of populations or have not covered large parts of the genome.

Although geneticists knew that Africans show more genetic diversity within groups than non-Africans do, the details of genome-wide variation in many populations remained unclear.

“We just didn’t know as much as we should about African population genetics,” said Molly Przeworski, from the University of Chicago.

A team led by geneticist Sarah Tishkoff of the University of Pennsylvania in Philadelphia has now published research that includes DNA samples from 2,432 Africans from 113 populations, including groups in Nigeria, Cameroon, Tanzania, Kenya and the Sudan plus non-African samples from Yemen.

They looked for differences at 1,327 sites in the genome and combined the results with existing genetic data from 8 African and 59 non-African groups.

The team then ran statistical analyses to cluster the individuals by genetic similarity and determine their ancestry.

The results confirm that Africans have the highest within-population diversity worldwide, and suggest that they originated from 14 ancestral groups.

Most African populations seem to show genetic traces from multiple ancestral groups, supporting previous archaeological and linguistic evidence for migrations across the continent that would have led to mixing.

The analysis also suggests that hunter-gatherers from different regions and cultures, including pygmies in central Africa and click-language groups in southern Africa, may have descended from one ancestral population.

The genetic clusters generally aligned with ethnicity and language, although the team found exceptions in cases where groups had lost, or possibly replaced, their languages.

While the overall results are not surprising, the study gives a fine-scaled view of genetic variation across a large number of African populations, according to Noah Rosenberg, a geneticist at the University of Michigan, Ann Arbor, who plans to collaborate with Tishkoff.

“They show just how much diversity in Africa actually exists,” he said. (ANI)

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