Revisiting the "Out of Africa" Theory: A New Narrative from Genetic Analysis and Artificial Intelligence

Researchers from Estonia and Italy have developed an innovative approach by combining neural networks and statistics. Using this newly developed approach, they refined the idea of "going out of Africa". The researchers claim that the African dynamics before and after the "out of Africa" expansion were more complex than previously thought.

Archaeologists and geneticists agree that all modern humans originated somewhere in Africa around 300,000 years ago. The movement of people who colonized the rest of the globe occurred about 60,000-70,000 years ago. Studies of Y chromosome data (following paternal ancestry) and mitochondrial genomes (following maternal ancestry) agree with this. However, the exact relationship between those who leave Africa and the human population currently living on the continent is not fully understood.

A simple model can look at the first stage of intra-African demographic differentiation, followed by the separation between the ancestors of modern Eurasians and the ancestors of modern East africans or North-East Africans. A new study on this topic, recently published in the American Journal of Human Genetics, suggests that there was a major population movement from East to West Africa before expansion outside Africa. This event could homogenize West and East Africans. This replacement may account for 90 percent of the gene pool in contemporary West Africa, increasing affinity between West Africans and Eurasians. This event better explains the lower limit of the time of separation between Africans and non-Africans extrapolated from genetic data (about 60,000 years ago).

"Similar hypotheses have been proposed previously on the Y chromosome. But this is the first time we've demonstrated this for autosomal DNA," said Lead author Francisco Montinaro of the study from the University of Bari. Autosomal DNA comes from both parents, not the Y chromosome or mitochondria, which come from only one of our parents.

"It's fascinating to see our understanding of the human past becoming more complex and detailed." Lead co-author Vasili Pankratov from the University of Tartu said: "Our new model can give us a clue as to why west Africa and the population outside of Africa show such a young separation time. "