In eight samples of 87-98 percent of human DNA comes from Neanderthals.
An international group of scientists, including Russian experts, found that the mud in the cave might contain the DNA of extinct species of people. To such conclusion researchers have come, having analysed sediments at archaeological sites in Western Europe and Russia. The scientific results published in the journal Science.
It is known that organic and mineral substances contained in the cave clays can bind nucleic acids. In past studies, scientists were able to isolate from the sediment of mitochondrial and chloroplast DNA belonging to animals and plants respectively. In the new work, the biologists analyzed 85 samples from seven archaeological sites (including Denisova cave), in which was discovered human remains or traces of life of the people of the Pleistocene epoch. The age of all the samples made up 14-550 thousands of years.
From each sample, the researchers were able to identify 38-160 milligrams of DNA. Hybridization analysis with fragments of nucleic acids was combined with a known sequences (probes), allowed to identify only a small part of the ancient genetic material. With almost all of it belonged to extinct animals, and DNA hominines was found only in one sample.
The scientists repeated hybridization analysis, however, this time the isolated DNA was connected to the probes target only the genetic material of humans. This time hominine genome fragments were detected in 15 samples from four archaeological sites. Their antiquity is indicated by the presence of a large number of thymine at the ends of pieces of DNA (nitrogenous base, over time, replaced by other base — cytosine). After this, the researchers analyzed the fragments of nucleic acids for the presence of sequences characteristic of Neanderthals (Homo neanderthalensis) and denisovans Heidelberg man (Homo heidelbergensis).
Found that in eight samples of 87-98 percent of human DNA comes from Neanderthals, 4-11 per cent, and 0-2 per cent of the denisovans and 0-2% Heidelberg man. In the ninth sample (Denisova cave), 84 percent of the DNA belonged to denisovans.
These results are consistent with the fact that the Neanderthal remains were really found in those caves, where a large part isolated from sediments, DNA belongs to the view of ancient people. However, the force method proves that it showed the presence of residues of the genome of H. neanderthalensis in those places where the fossils of archaic man was not preserved, although there were found artifacts of the Neanderthals.
DNA of extinct species of people of interest to scholars, since it is possible to reconstruct the history of evolution and resettlement around the world of modern man (Homo sapiens) and those of his closest relatives like Homo erectus (Homo erectus), Neanderthal, or denisovans. So, according to genetic material extracted from the remains of the denisovans, the scientists were able to decipher their complete genome and identify what they are closer to Neanderthals than to Homo sapiens.
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