Long lost sisters( The human race was divided into two ...)

The human race was divided into two separate groups within Africa for as much as half of its existence, says a Tel Aviv University mathematician. Climate change, reduction in populations and harsh conditions may have caused and maintained the separation.

Dr. Saharon Rosset, from the School of Mathematical Sciences at Tel Aviv University, worked with team leader Doron Behar from the Rambam Medical Center to analyze African DNA. Their goal was to study obscure population patterns from hundreds of thousands of years ago.

Rosset, who crunched numbers and did the essential statistical analysis for the National Geographic Society's Genographic Project, said the team was trying to understand the timing and dynamics of the split into at least two separate groups.

We wanted to look into the ancient history of our species. How did we live throughout most of our existence as a species" Did we live as one or were we fractured into small groups" Until now, it wasnt really clear, says Rosset.

Researchers believe that about 60,000 years ago, modern humans started their epic journeys to populate the world. This time period has been the primary focus of anthropological genetic research. However, relatively little is known about the demographic history of our species over the previous 140,000 years in Africa.

The current study returns the focus to Africa and thereby refines the understanding of early modern Homo sapiens history.

Rosset, who is also affiliated with IBMs T.J. Watson Research Center in New York, says the study provides insight into the early demographic history of human populations before they moved out of Africa. These early human populations were small and isolated from each other for many tens of thousands of years, says Rosset.

The teams research was based on a survey of African mitochondrial DNA (mtDNA) and is the most extensive survey of
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