A new study published in the Proceedings of the National Academy of Sciences (PNAS) gives us some details on the so-called blending events that have seen modern men join different groups of archaic humans in the course of their history following their departure from Africa.
It is thought that modern human beings crossed with at least five different archaic human groups in the course of their history that saw them move from Africa through Eurasia to Southeast Asia and beyond. Two of these archaic groups are known: the Neanderthals and the Denisovans group. The others remain unknown although DNA analysis shows the union of our ancestors with other different populations.
In particular, according to the researchers, it was the area of South-East Asia that was a “hotbed of diversity.” As João Teixeira, a researcher at the University of Adelaide, specifies the first author of the study, “These archaic groups were widespread and genetically different and survive in each of us. Their story is an integral part of what we have become.”
An example is given by the fact that today’s populations show in their DNA about 2% of the DNA of the Neanderthals. This, and other genetic data, shows that mixing with Neanderthals must have taken place almost immediately after our ancestors left Africa, in a period between about 50,000 and 55,000 years ago somewhere in the Middle Orient. However, our ancestors, traveling further east, met and mixed with other different groups of humans.
Using various information regarding these migratory routes, the researchers concluded that an important mixing event must have occurred in the areas of southern Asia, in Southeast Asia, with a group that was named “Hominino Estinto 1.” Other crossings, probably of lesser incidence, must then have taken place in East Asia, in the Philippines and near the island of Flores, Indonesia, with another group that the same researchers called “Hominino Estinto 2.”
This information shows that the history of our ancestors once they left Africa seems to be much more complex than I previously deduced and that the South East Asian region played a very important role in the mixing events that led to modern men thanks also to a relative geographical isolation of these populations for hundreds of thousands of years.
Furthermore, this information also suggests that the disappearance of these archaic human populations occurred substantially coinciding with the arrival of modern humans.