While scientists are quite confident that modern humans originated from Africa, they’re unclear on the routes they took to move out of the continent. Researchers may have just provided a clearer picture of this epic journey and settled the long-standing debate. The latest study, published in the American Journal of Human Genetics, suggests early humans traveled through Egypt—not Ethiopia—on their voyage out of Africa.
Scientists have previously been unable to distinguish whether early humans migrated by the southern route, through Ethiopia and the Arabian Peninsula, or exited by the northern path—through Egypt and Sinai. For the study, researchers collated and analyzed whole-genome sequences from 225 people from modern Egypt and Ethiopia to investigate the two proposed ‘gateways’ for early humans' route out of Africa.
"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. 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," says Dr. Luca Pagani, first author from the Wellcome Trust Sanger Institute and University of Cambridge, in a statement
"This information will be of great value as a freely available reference panel for future medical and anthropological studies in these areas," Pagani adds.
If early humans traveled through Egypt, then the researchers expected Egyptians to be more genetically similar to modern non-Africans. If they traveled through Ethiopia, however, then Ethiopians should be genetically closer to modern non-Africans.
Previous studies have shown that the genomes of present-day Egyptians and Ethiopians have been affected by the recent gene flow from West Asian populations, so researchers excluded the recent non-African ancestry found in the genomes of Ethiopians and Egyptians. The study showed that the remaining genomes from Egyptian samples had higher frequencies outside of Africa and more closely resembled non-African genomes.
"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," says Dr. Toomas Kivisild, a senior author from the Department of Archeology and Anthropology, University of Cambridge.
The researchers hope that with more ancient genomic data, they will be able to further unravel the ‘complexities’ of early human migration, addressing specific controversies on timing and whether other migrations occurred that are not present in modern genomics.