A novel 30 thousand years long
Neanderthals interbred with sapiens much more often than was thought
Yulia Vorobyova, Vesti
Scientists have long established that modern humans are carriers of Neanderthal DNA. It was assumed that this was the result of a short-lived "interspecies romance".
However, a new work by researchers from Temple University in the USA refutes this opinion. Apparently, the connection between the ancient Sapiens and their "cousins" was not fleeting. On the contrary, the species Homo neanderthalensis and Homo sapiens interbred repeatedly, and for quite a long period of time, the researchers say.
Recall that the ancient people left their African "cradle" about 100 thousand and, having passed the Middle East, began to settle across the vast territories of Eurasia about 75 thousand years ago. Neanderthals, who had already settled on the mainland by that time, died out about 40 thousand years ago. Obviously, for more than 30 thousand years, they and our ancestors enjoyed sexual compatibility.
Approximately 2% of human DNA serves as a reminder of these relationships today. In fact, the only modern humans devoid of Neanderthal genes are the descendants of those ancient homebody Sapiens who did not travel from Africa to the north.
However, a closer study and comparison of the genomes of modern humans prompted scientists to think that there were actually much more crosses with Neanderthals than was thought.
Recent work has shown that people living in East Asia have much more Neanderthal DNA than native Europeans. The difference is from 12 to 20%.
This suggests that Neanderthals and Sapiens did not have a "one-night stand", but rather a long-term relationship, the authors of the work reasoned. However, they needed to back up their theory with evidence.
To do this, the researchers used a database of genetic data collected as part of the 1000 Genomes Project. They compared samples of Neanderthal DNA and human DNA with East Asian and European ancestry. The results confirmed that the ancestors of both groups were repeatedly crossed with "cousins".
Then the specialists applied a modeling technique and used a machine learning algorithm to consider all possible variants of "love events" that could lead to the appearance of the percentage of Neanderthal DNA that is observed in the genome of modern humans.
The results showed that there were indeed much more episodes of crossing than was thought. Moreover, interactions between sapiens and Neanderthals, apparently, were equally frequent in both Europe and East Asia.
However, experts still find it difficult to explain why the genome of people with East Asian roots contains more Neanderthal DNA.
In the future, researchers intend to find answers. They also believe that the difference in the number of Neanderthal genes in modern Asians and Europeans will help clarify the geographical movements of populations of Neanderthals and Sapiens and find out how long certain groups lived in a particular region and coexisted together.
More about this work is described in an article published in the journal Nature Ecology & Evolution.
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