If you think that freckles, red hair or even narcolepsy you got from Neanderthal, to worm his way into your family tree, make no mistake. Indeed, people around the world have genomes of DNA fragments of this ancient man. But according to a study in the frames of which were studied the data of tens of thousands of Icelanders have inherited from Neanderthals DNA or do not affect their physical traits and health, or affect very little.
Experts in the field paleogenetic about ten years ago came to the conclusion that most of the inhabitants of Europe and Asia from 1 to 2% of their genome inherited from Neanderthals. The Melanesians and the Australian aborigines, others 3-6% of the DNA received from the Denisovsky person related to the Neanderthals species that lived in Asia somewhere between 50 and 200 thousand years ago.
One by one published the study that says that variants of genes inherited from these ancient species, can increase the risk of depression, diabetes, blood clots and other ailments from living people. It is possible that this DNA also changes the shape of our skull, strengthens the immune system and affects eye color, hair color and sensitivity to the sun. This is evidenced by the results of the analysis of genetic and medical information that is stored in the biobanks and medical databases.
But a new study in which the DNA of extinct species of people looking for the genes of the modern inhabitants of Iceland, questioned many of these claims. Scientists from Aarhus University in Denmark have studied the complete genomes 27566 Icelanders from the database of the Icelandic company deCODE Genetics. They were looking for unusual variants of genes of extinct species. In the end, the experts received a huge catalogue of supposedly “archaic” variants, where they were from 56 to 112 thousand. The results of the study were unexpected.
So, researchers found that 3.3% of “archaic” DNA Icelanders have inherited from the Denisovsky person, and 12.2% received from unknown sources (84,5% inherited from close relatives of the Neanderthals whose genomes were used in the study).
In addition, they examined 271 sign of the body and to check how they are defined and Denisovskaya Neanderthal DNA. Unlike most previous studies, this time was studied complete genomes. This allowed the scientists to determine the impact of these characteristics on the genes of modern man. As it turned out, most of the signs were easier to associate with the modern variants of genes. DNA of extinct species had a significant influence only on the five features, reported scientists in the journal “nature” (Nature). Men with one “archaic” variant of the gene was slightly less prone to prostate cancer. Two other options, presumably, accelerate blood clotting in men and women and also make them shorter, said the expert on bioinformatics of Laurits SKOV (Laurits Skov) from Institute for evolutionary anthropology. Max Planck, who led the study during his work in Aarhus, and deCODE Genetics.
At the same time scientists have not been established no statistically significant relationship between the DNA of extinct species and freckles, hair color, eyes and the development of autoimmune diseases such as Crohn’s disease and lupus, which is contrary to the results of previous studies. Experts came to the conclusion that the fragments of Neanderthal DNA have limited impact on such sloye signs, such as height or susceptibility to depression, because they involve the interaction of many genes (scientists have not considered the impact of genes on the shape of the skull or immune function, which presumably are associated with Neanderthal DNA).
Population geneticist Joshua Eiki (Joshua Akey) from Princeton University, called the discovery Denisovskaya DNA of Icelanders “striking”. As he notes, it is unlikely that the denisovans had sailed to Iceland in boats and brought his DNA. Most likely, even long before the present-day Icelanders reached the island, there was a crossing of a Neanderthal or a modern human with Denisova.
The relatively weak influence of Neanderthal DNA on the majority of topics is not surprising, since our genomes are mostly represented DNA of modern man, he adds. A specialist in the field of computational biology Janet Kelso (Janet Kelso) from the max Planck Institute has confirmed his words, but at the same time declared that the impact of DNA of extinct species to Icelanders and other populations may be different.
According to the head of deCODE Genetics and lead author of the study Kauri Stevenson (Kári Stefánsson), “you just need to accept the fact” that the contribution of Neanderthal DNA was not as significant as claimed by previous studies. However, his team plans to continue the work to finally to understand. So, they look like Neanderthal and Denisov expressed genes of the Icelanders from the database, deCODE Genetics, studied the levels of more than 5 thousand proteins.