Scientists from Estonia and Italy have collaborated to develop a unique technique by integrating neural networks and statistics. The “Out of Africa” scenario was refined using the new technique.
According to the researchers, the African dynamics that persisted during the Out of Africa expansion are more complicated than previously predicted.
The theory that all humans originated in Africa about 300 thousand years ago is a concept well-agreed by archaeologists and geneticists. The migration that colonized the rest of the world happened roughly 60,000 to 70,000 thousand years ago.
The Y-Chromosomal data that follows patrilineal lineage and the Mitochondrial genome that follows matrilineal line confirms this. However, the exact relationship between the population that moved out of Africa and the population presently inhabiting Africa needs to be studied more.
A simple model will consider the initial phase of within-African population subdivisions, followed by a separation between the ancestors of modern Eurasians and the ancestors of the modern East or North-East Africans.
The study was published in the American Journal of Human Genetics.
According to the new study, before the Out of Africa expansion, a notable population turnover occurred from East to West Africa. This event has likely homogenized the people of West and East Africa. This turnover, which comprises almost 90% of the contemporary West African gene pool, raised the affinity between West Africans and Eurasians.
This event details the lower bound which dates back to almost 60,000 years ago, derived from genetic data for the separation time between Africans and non-Africans.
A similar hypothesis was proposed before for the Y chromosome. But this is the first time we demonstrated it for autosomal DNA.
Francesco Montinaro, Study Lead Author, University of Bari
Unlike the Y-chromosome or Mitochondria that comes from any one of the parents, the autosomal DNA comes from both the parent.
It is fascinating to see how our understanding of the human past becomes ever more complex and detailed. Our new model can give us a clue why West Africa shows such a young separation time from the out of Africa populations.
Vasili Pankratov, Study Lead Co-Author, University of Tartu
Montinaro, F., et al (2021) Revisiting the out of Africa event with a deep-learning approach. American Journal of Human Genetics. doi.org/10.1016/j.ajhg.2021.09.006.*