Around 100,000 years ago, Neanderthals lived for many generations in the Atapuerca ridge in northern Spain, as indicated by stone tools, ancient fireplaces and bones from hunted animals. Researchers have now succeeded in recording the genetic traces of the long-gone residents: a team of genome specialists from the Max Planck Institute for Evolutionary Anthropology in Leipzig was able to extract and analyze DNA traces of the Neanderthals from soil samples in a cave. Benjamin Vernot, Matthias Meyer and their colleagues were also able to examine the sequence of genetic material from the cell nucleus for the first time. This is a huge technical leap. Previously it had only been possible to get the traces of mitochondrial DNA, which were present in significantly larger quantities, from the soil dust from settlement areas that were once used for a long time.
In the future, the new technology should make it possible for early humans to hunt for ancient traces of genetic material in many old settlements with a chance of success. To do this, it is not even necessary to find bone, tooth or skull fragments from which DNA residues previously had to be extracted. In this way, researchers can then draw a much more comprehensive picture of the people who settled Europe in the Pleistocene.
In their current study, published in Science, the researchers describe their search for DNA traces in three caves that were inhabited by Neanderthals and other early humans: the Spanish Estatuas Cave and the Denisova and Chagyrskaya Caves in Siberia. In all three caves, the researchers were able to isolate old human nucleus and mitochondrial DNA from soil samples and use gene samples to differentiate them from the genetic make-up of microorganisms, plants and animals, which make up almost the entire amount of all DNA traces collected at all locations.
With the successfully isolated genetic material from Spain, the local and regional history of colonization can now be roughly traced: The researchers found traces of a male Neanderthal who lived 113,000 years ago and was largely related to the group of early humans who lived a little earlier had lived in western Siberia and in what is now Belgium and Germany. Later, however, a new group inhabited the cave in Spain, as evidenced by the genetic make-up of two female Neanderthals who lived around 100,000 years ago. They resemble the later “classical” Neanderthals who only settled in Europe later and lived 70,000 years ago in Croatia and 60,000 years ago in the Russian Altai. The more modern Neanderthals differ from the older ones, among other things, in their larger skull volume.
The mitochondrial DNA found in the cave from other early humans of different generations also makes it clear that the genetic diversity of the population has gradually decreased – probably because the population of Neanderthals as a whole has become ever smaller. Researchers had previously drawn similar conclusions from the analysis of mitochondrial genetic material. The success of the Neanderthals probably also depended on the climatic conditions: while they were able to venture into northern Europe in relative warm periods, their population collapsed in colder periods.
The Leipzig MPI scientists would like to use their new technology to search for old DNA traces in further caves in the future. In the end, this could provide a much more comprehensive look at the genetic history of humans and their migratory movements during the Ice Age.
Article source: spektrum.de
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