By - - PHYSORG.COM
Added: Thu, 14 Jul 2011 14:44:07 UTC

Researchers have probed deeper into human evolution by developing an elegant new technique to analyse whole genomes from different populations. One key finding from the Wellcome Trust Sanger Institute's study is that African and non-African populations continued to exchange genetic material well after migration out-of-Africa 60,000 years ago. This shows that interbreeding between these groups continued long after the original exodus.

For the first time genomic archaeologists are able to infer population size and history using single genomes, a technique that makes fewer assumptions than existing methods, allowing for more detailed insights. It provides a fresh view of the history of mankind from 10,000 to one million years ago.

"Using this algorithm, we were able to provide new insights into our human history," says Dr Richard Durbin, joint head of Human Genetics and leader of the Genome Informatics Group at the Sanger Institute. "First, we see an apparent increase in effective human population numbers around the time that modern humans arose in Africa over 100,000 years ago.

"Second, when we look at non-African individuals from Europe and East Asia, we see a shared history of a dramatic reduction in population, or bottleneck, starting about 60,000 years ago, as others have also observed. But unlike previous studies we also see evidence for continuing genetic exchange with African populations for tens of thousands of years after the initial out-of-Africa bottleneck until 20,000 to 40,000 years ago.

"Previous methods to explore these questions using genetic data have looked at a subset of the human genome. Our new approach uses the whole sequence of single individuals, and relies on fewer assumptions. Using such techniques we will be able to capitalize on the revolution in genome sequencing and analysis from projects such as The 1000 Genomes Project, and, as more people are sequenced, build a progressively finer detail picture of human genetic history."
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TAGGED: EVOLUTION, GENETICS