Humans went north 'out of Africa', not south

John Hopton for redOrbit.com – @Johnfinitum

It is now widely accepted that modern humans had African origins – the “out of Africa” theory – but for a long time the route they took when migrating out and populating the planet has been up for debate.

Now, new research published in the American Journal of Human Genetics suggests they took the “Northern Route” via Egypt, rather than the “Southern Route” via Ethiopia.

The researchers used whole-genome sequences from 225 people from modern Egypt and Ethiopia and excluded gene flow from West Asian populations that have since contributed to modern African populations.

The remaining masked genomic regions from Egyptian samples were more similar to non-African samples and present in higher frequencies outside Africa than the masked Ethiopian genomic regions, pointing to Egypt as the more likely gateway en route to the rest of the world.

“The most exciting consequence of our results is that we draw back the veil that has been hiding an episode in the history of all Eurasians, improving the understanding of billions of people of their evolutionary history,” said Dr. Luca Pagani, first author from the Wellcome Trust Sanger Institute and University of Cambridge.

“It is exciting that, in our genomic era, the DNA of living people allows us to explore and understand events as ancient as 60,000 years ago.”

“The last stop”

The team also used high-quality genomes to estimate the time that the populations split from one another, and found that people outside Africa split from the Egyptian genomes more recently than from the Ethiopians (55,000 as opposed to 65, 000 years ago). This further supports the theory that Egypt was the “last stop” in Africa during the exodus.

“While our results do not address controversies about the timing and possible complexities of the expansion out of Africa, they paint a clear picture in which the main migration out of Africa followed a Northern, rather than a Southern route,” said Dr. Toomas Kivisild, a senior author from the Department of Archaeology and Anthropology, University of Cambridge.

More work to be done

Dr. Chris Tyler-Smith, a senior author from the Wellcome Trust Sanger Institute, said: “This important study still leaves questions to answer. For example, did other migrations also leave Africa around this time, but leave no trace in present-day genomes? To answer this, we need ancient genomes from populations along the possible routes. Similarly, by adding present-day genomes from Oceania, we can discover whether or not there was a separate, perhaps Southern, migration to these regions.

“Our approach shows how it is possible to use the latest genomic data and tools to answer these intriguing questions of our human origins and migrations.”

The extensive public catalogue of the genetic diversity in Ethiopian and Egyptian populations developed for the project also provides a valuable, freely available, reference panel for further medical and anthropological studies.

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Source: http://www.redorbit.com/news/science/1113398834/humans-went-north-out-of-africa-not-south-052815/