A few years ago, the human genome was completely analyzed, and scientists found that about 3% of our genes came from Neanderthals. In addition, some of these genes are linked to life-threatening diseases. How is this possible?
In 2010, a study was conducted on 60% of Neanderthal nuclear DNA. The DNA comparison showed that the genomes of non-Africans are much closer to Neanderthal than those of Africans. It also showed that 1 to 4% of the current human genome could come from Neanderthals and is absolutely not present among Africans. Richard E. Green, lead author of the study, said that “in all probability, there has been a flow of Neanderthal genes to modern humans”.
In 2014, two American studies brought new elements. The sequences inherited from Neanderthal man are not identical in all humans whether European, Asian or African, there is so in us a great variety. Indeed, each individual would have between 1 and 4% of the genome of Neanderthal in him, and the fact is that by grouping the different sequences scattered around the world, researchers have managed to reconstitute about 40% of the same genome!
Moreover, this contribution of the genome in today’s men is not really beneficial, at least in terms of certain genes in particular. Scientists believe that there is a link between the Neanderthal genes and different conditions or problems such as type 2 diabetes, tobacco addiction, biliary cirrhosis, Crohn’s disease or lupus erythematosus. There is even a link to a sexually transmitted disease: the human papillomavirus (HPV).
However, the researchers were even more surprised to discover what they call “Neanderthal deserts”, areas of our body that have received no contribution from our distant ancestor. In this case, let us mention the X chromosome or the parts containing active genes located in the testes.
This is explained by the gradual and partial evacuation of Neanderthal inputs by natural selection. Thus, researchers believe that perhaps the hybrids had problems of infertility, which would explain why Sapiens and Neanderthals had become incompatible. Recall that they evolved separately even though they came from a common ancestor who lived 500, 000 years ago.