According to a study which was published in the American Journal of Human Genetics on Thursday modern man’s interbreeding with the Neanderthals had both advantages and disadvantages: it has improved our immune system, but at the same time it has made some of us more prone to developing allergies.
Even though in 2010 he idea that modern humans have interbred with the primitive and ancient Neanderthals would not have been well-perceived, but now scientists have found enough evidence that modern humans interbred not only with the Neanderthals, but also with the Densovans, another species of ancient ancestors. Moreover, as a result of this, the Neanderthals gave us one to two percent of our DNA. It seems that these are the same genes which have an important role in the allergic reactions which people have to pet fur and pollen.
According to scientists around 50.000 years ago the modern humans had left Africa and reached the Neanderthal settlements in the Middle East. Now their interbreeding can be observed in the genomes of people who have ancestors in Asia and Europe. Scientists say that in the case of Asian and European populations the Neanderthal genes involved in allergies can be found in 50 percent of the population. Senior author of the study, evolutionary geneticist Lluis Quintana-Murci from the Pasteur Institute in Paris, said that this is a huge percentage and it came as a big surprise for the scientists.
The three genes in question are collectively known as TLR6-TLR1-TLR10 and they compose our innate immune system which reacts to virus and bacteria invasions.
Researcher Janet Kelso from the Max Planck Institute for Evolutionary Anthropology in Leipzig (Germany) who was also involved in the study remarked that this theory might be a bit of a speculation and it described it as a “trade-off”, saying that our ancestors provided us with an enhanced resistance to bacterial infection, but this also led to an enhanced sensitivity to allergens that are not pathogenic.
Professor of microbiology and immunology Peter Parham from the Stanford School of Medicine, was not involved in the research, but he commented on the study saying that the findings suggest that these genes were very important for the Neanderthals since they are still present in our genome today and moreover at a really high frequency. If the genes would not have been important they would no longer exist today. He also added:
It suggests there was a benefit for the migrating modern human and the archaic human to get together.What has survived is a hybridization of those populations.”
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