Genetics received the first direct evidence that contact with Neanderthals helped our ancestors, the migrants from Africa to adapt to the harsh conditions of the North in Asia and Europe.
Our work shows that hybridization was not just a curious fact on the margins of the book of human history, and had important consequences for us and helped our ancestors to acquire the ability to adapt to different environmental conditions as they spread along the Ground, said Joshua Aki (Joshua Akey) from the University of Washington in Seattle (USA).
The resurrection and the Neanderthal genome project, conducted by Svante Paabo and his team in 2009, showed that Neanderthals had contact with our ancestors and left in our DNA approximately 2-4% of their genes. Of these genes, as shown by further research, has helped the CRO-magnons to adapt to life in the North, giving them a powerful immune system and other beneficial features.
On the other hand, mathematical simulation, built on the basis of this resurrected DNA showed that interbreeding of humans and Neanderthals was extremely rare to end well, what made scientists look for the causes of this phenomenon. One possible reason for this was considered to be degeneration of the Neanderthals due to the excessively small size of their population, or almost complete genetic incompatibility with the CRO-magnons.
Aki and his colleagues have shown that even these small traces of DNA played a big role in the lives of our ancestors, examining how often the scraps and Denisovskaya Neanderthal DNA found in the genomes of modern humans.
Pursuing the study of genetics proceeded from a simple assumption – if the Neanderthal gene variations were purely random and were not particularly the right person, then they had to either completely disappear from our DNA, or meet in it rather seldom. On the other hand, if the genes of ancient people was critical to the survival of the CRO-magnons and their modern descendants, then such variations should meet virtually in the DNA of every human being.
Following this idea, the team Aki analyzed sets of small mutations in the DNA of several hundred modern humans and compared them with the structure of the genes in the genome of Neanderthals, Paabo resurrected and colleagues.
In total they were able to identify 126 Neanderthal DNA, the structure of which is surprisingly often met among the people of Europe, and among Asians – these gene variants, according to scientists, has two-thirds of the people of all continents except Africa.
These seven DNA regions located in genes related to skin pigmentation and reaction to UV light, and another three dozen sites are responsible for the immune system, including innate cellular response to various fungi, viruses and bacteria, including influenza and acute respiratory diseases.
The fact that these variations are present in the genome of almost every one of us speaks to the fact that they were useful for the survival of our ancestors. This underlines the fact that such traces are in genes related to immunity, which the fastest change in our body. Interbreeding with Neanderthals was an effective way to accelerate evolution and adaptation to new conditions, and this took the ancient people concludes Aki.