Although scientists are confident that all modern human populations can trace their ancestry back to Africa, the route taken out of Africa is still unclear. New genomic analyses of people currently living in Ethiopia and Egypt indicate that Egypt was the major gateway out of Africa and that migration followed a northern rather than a southern route. The findings, which appear online on May 28 in the American Journal of Human Genetics (AJHG), add a crucial piece of information to help investigators reconstruct humans' evolutionary past.
To uncover the migratory path that the ancestors of present-day Europeans and Asians (Eurasians) took when moving out of Africa around 60,000 years ago, Dr. Luca Pagani, of the Wellcome Trust Sanger Institute and the University of Cambridge in the UK, and his colleagues analyzed the genetic information from six modern Northeast African populations (100 Egyptians and five Ethiopian populations each represented by 25 people).
"Two geographically plausible routes have been proposed: an exit through the current Egypt and Sinai, which is the northern route, or one through Ethiopia, the Bab el Mandeb strait, and the Arabian Peninsula, which is the southern route," Dr. Pagani explains. "In our research, we generated the first comprehensive set of unbiased genomic data from Northeast Africans and observed, after controlling for recent migrations, a higher genetic similarity between Egyptians and Eurasians than between Ethiopians and Eurasians." This suggests that Egypt was most likely the last stop on the way out of Africa.
In addition to providing insights on the evolutionary past of all Eurasians with their new findings, the researchers have also developed an extensive public catalog of the genomic diversity in Ethiopian and Egyptian populations. "This information will be of great value as a freely available reference panel for future medical and anthropological studies in these areas," says Dr. Pagani.
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