DNA from the ground
Microparticles rich in DNA of ancient people were found in the soil of Denisova cave
Thanks to this, it will be easier for scientists to determine the gender, appearance and other features of the inhabitants of such caves
In soil samples from the Altai Denisova cave, scientists found microscopic particles unusually rich in ancient DNA. Their discovery helped scientists link the soil fossil DNA with the remains of Neanderthals found in this cave. The description of the study was accepted for publication by the journal Proceedings of the National Academy of Sciences (Massilani et al., Microstratigraphic preservation of ancient faunal and hominin DNA in Pleistocene cave sediments, in press).
"The ancient DNA that we previously extracted from the soil of Denisova Cave is concentrated inside microscopic particles, and not evenly distributed over the soil. This revealed the origin of this ancient DNA and indicated in what conditions it is most often preserved," she said Vera Aldeas from the University of the Algarve in Faro (Portugal).
Anthropologists announced the discovery of a previously unknown species of Homo sapiens – the so–called Denisovans - ten years ago. Archaeologists who worked in the Denisova Cave in Altai have been finding their remains since the mid-1980s, but scientists were able to understand that this is a new species much later. This was due to the fact that the researchers were able to extract and study fragments of the genome of Denisovans that were preserved inside the preserved teeth and knuckles.
Initially, the discoverers of the Denisovans believed that the ancient inhabitants of Altai were relatives of the Neanderthals who lived in the Denisova cave about 50 thousand years ago. Subsequently, it turned out that the Denisovans appeared much earlier and were a separate subspecies of people whose DNA traces were preserved in the genomes of modern Polynesians, Indians of South America and a number of peoples of Southeast Asia.
Four years ago, scientists led by Matthias Meyer discovered fragments of Neanderthal DNA in the soil of Denisova Cave. Their study helped scientists prove that Homo neanderthalensis settled it later than Denisovans. Aldeas, Meyer and their colleagues studied the cave soil samples very carefully in the hope of understanding how fragments of the genomes of different Neanderthals and Cro-Magnons got into it. Paleogeneticists also studied sediment samples from several dozen other caves and sites of ancient people collected by their colleagues in recent years in different regions of Eurasia.
Having prepared thin slices of these soil samples, the scientists compared how many fragments of Neanderthal and Cro-Magnon DNA were in them, as well as fragments of the genome of various animals. It turned out that the fossil DNA of ancient humans and mammals was concentrated in individual microscopic particles of the soil, and not evenly distributed throughout its thickness, as paleogeneticists expected.
Scientists also found out that these samples were directly related to the inhabitants of Denisova Cave and those sites of ancient people, from where soil samples were extracted. In particular, Aldeas and her colleagues managed to link DNA fragments from the soil of Denisova Cave with a fragment of a Neanderthal bone found near the point of soil sampling.
As scientists suggest, the particles they found with a high proportion of DNA are microscopic fragments of bones of ancient people and animals, as well as their fossilized feces. This discovery greatly simplifies the search and identification of fossil DNA in the soil of caves, and also allows scientists to use these fragments to determine the gender, appearance and other features of the ancient inhabitants of these sites.
In addition to this, scientists have found that the concentrated nature of the deposits of fossil DNA in the soil allows us to look for traces of it even in those samples that have been stored in museums and vaults of institutes for several decades. In the near future, Meyer and his colleagues plan to analyze a large number of such soil samples, which, they hope, will significantly enrich the ideas of anthropologists and paleogeneticists about the populations of ancient people.
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