An article published in the journal “Science Advances” reports a study carried out on the DNA of two Neanderthals who lived in today’s Germany and Belgium about 120,000 years ago. A team led by Dr. Stéphane Peyrégne of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, used genetic data obtained from bones still in good condition of the two individuals, concluding that they were members of a population from which all of the later identified Neanderthals descended except the ones who lived on the Altai Mountains in Siberia.
The femur of a Neanderthal man discovered in 1937 in the Hohlenstein-Stadel Cave, in Germany, and the maxillary bone of a girl of the same species discovered in 1993 in the Scladina Cave, in Belgium, were subjected to a genetic examination by researchers of the Max Planck Institute for Evolutionary Anthropology of Leipzig, which among other things is at the forefront of paleogenetics, a specialization concerning the DNA of ancient, even extinct, organisms.
Advances in genetic techniques made it possible to at least partially extract the DNA of various Neanderthals and this is helping to reconstruct their history, linked to that of modern humans given that between the two species there were many interbreedings that can now be proved precisely through genetic exams. Today we know that in the last period of their existence, the Neanderthals who lived in Europe and Central Asia belonged to a genetically homogeneous group while a genetically separated group lived in Denisova Caves in Siberia, at least in various periods together with another species of humans called Denisovans precisely because almost all of their remains were discovered in those caves.
Each new Neanderthal DNA fragment is useful to better understand the history of this species studying it over tens of thousands of years. Stéphane Peyrégne, lead author of the research on these two genomes, explained that we know little about the history of this species over the hundreds of thousands of years it existed and to understand more it’s useful to study the relationships between the different groups that lived in Europe and Asia.
The results of comparing the two genomes with those of two Neanderthals who lived in Denisova Caves 90,000 and 120,000 years ago and those of individuals who lived in Europe 40,000 years ago offered some surprises. The researchers found that the individual who lived in Denisova Caves 90,000 years ago is more closely related to the European Neanderthals from 120,000 years ago than to the individual who lived in the same caves 30,000 years earlier. This suggests an eastward migration that led to the replacement of the Neanderthals who already lived in those areas.
Another result is that the Neanderthals who lived 40,000 years ago in Europe were closely related to those who lived 120,000 years ago. This indicates that there was stability for a very long time in that population, which perhaps represented the main area in which that species lived. Kay Prüfer, who supervised the study, pointed out the remarkable contrast to the history of modern humans, made up of genetic replacements and interbreedings of entire populations.
A problem still to be explained is the one arrived from the analysis of the mitochondrial DNA of the man who lived in the Hohlenstein-Stadel Cave, which turned out to be quite different from those of other Neanderthals. The results of that analysis were described in an article published in July 2017 in the journal “Nature Communications”. The hypothesis of an interbreeding with a population that is still unknown remains the most likely but it’s not possible to say whether these were other isolated Neanderthals and therefore still unknown or of a different species.
The researchers used sophisticated algorithms, including one developed for this study, to try to understand the relationships among the various Neanderthal populations and those with other archaic and modern humans. This is a long and complex task and its results can change significantly every time a new genome is analyzed that leads to the addition of new data. Among the few certainties, there’s the one that various species of hominins interbred over time, so the history of Neanderthals is partly that of modern humans as well.