How long does DNA last after death

Multiculturalism in the Stone Age Did humans just integrate the Neanderthals?

It must have been quite lonely in Europe and in the Middle East between 40,000 and 150,000 years ago. A study on the genome of Neanderthals published in the magazine "nature" suggests that never more than a few thousand of these prehistoric humans lived in the vast area that stretches from the French Atlantic coast in the west to the Altai Mountains in southern Siberia. The study also takes a new look at the end of the Neanderthals: Have modern humans perhaps not displaced them but integrated them?

The basis of these considerations is a small sensation that an international team of researchers headed by the Max Planck Institute for Evolutionary Anthropology (MPI EVA) in Leipzig has succeeded in: The scientists have deciphered the genome of five of these primeval people from the ancient remains of Neanderthals . This enabled them to double the number of known Neanderthal genomes to ten.

The closer together, the more closely related

The researchers put together a puzzle for this. "Such DNA is very long, there are several million base pairs that make up such a chromosome. After the death of an individual, it breaks into short pieces," says bioinformatician Kay Prüfer from MPI EVA. They were able to sequence the genome of two Neanderthals in high quality. "Really high quality means that we know at each point which base is there because we have produced several sequences that cover this point," he explains.

Most of the Neanderthals studied lived 39,000 to 47,000 years ago, when the first modern humans were in Europe. Her remains have been found in France, Belgium, Croatia and the Caucasus. The genetic make-up of an early man who lived 150,000 years ago in the Altai in Siberia was already known. A finding from the comparison between the gene sequences: The prehistoric humans were genetically more similar, the closer they lived together geographically.

"The genome from the Caucasus was a bit different than the others. In general, however, all the Neanderthals examined are very closely related to one another. That fits very well with our idea that it was a relatively small group that lived in Europe and Asia has, "says Prüfer.

Where exactly the individual groups lived has probably changed again and again over time. "Because glaciers formed and disappeared again and the climatic conditions changed, the Neanderthals probably had different distribution areas," says the bioinformatician. He and his colleagues assume that the groups met each other from time to time. "Since they are genetically closely related, they must have had children together."

Where did Neanderthals and modern humans meet?

Almost everyone today carries Neanderthal DNA, except for most sub-Saharan Africans. This fact is already known from previous studies. However, it is still unclear when and how this genetic material got into modern humans. Geneticists today can only say that the Neanderthals already lived after mixing with modern humans 70,000 years ago, but that their ancestors in Siberia 150,000 years ago had no contact with the Homo Sapiens.

One possibility, of course, is that the group of Neanderthals that mingled with us lived in the Middle East. That would be a simple explanation because we know that the modern people who populated Europe and Asia came from Africa. This group must have gone through this area, so Turkey, for example, would be a possible place.

Kay Prüfer, Max Planck Institute for Evolutionary Anthropology

Another question is why little Neanderthal DNA has been passed on to humans. Prüfer suspects that it could have been due to the numerical relationships between the different types of people. The Homo Sapiens were numerically far superior to the Neanderthals, the genetic material of the prehistoric humans could have been very diluted in the larger population. It is also possible that primitive humans did not simply become extinct, as scientists have previously assumed. Prüfer believes they could have simply been integrated and assimilated by the newcomers.

Maybe the offspring died

Another mystery is that the four youngest Neanderthals examined showed no traces of DNA from modern humans, even though both groups were already living together in Europe at that time. One explanation for this could be that prehistoric and present-day people did not meet in the vast landscapes. A second possibility would be that the common offspring of both groups did not survive.

The examiner considers the latter explanation plausible. Individual homo sapiens populations have also already died out. "We sequenced a person who lived in Siberia 45,000 years ago. He formed a third group between Asians and Europeans, is genetically the same distance from both. We have not yet seen any direct descendants from this individual, none of the people living now come from from him, "says the researcher.

The hope of Prüfer and his colleagues is that more Neanderthal genomes can be obtained from fossils in the future and that the individual parts will continue to condense to form a coherent picture.

We haven't yet managed to build a clearer model of where the intermingling of Neanderthals and modern humans happened, exactly how many Neanderthals came into the human population, and how it all fits together. You need a lot of individuals for that. Now we have maybe ten, so you can't do everything we imagine with it.

Kay Prüfer, Max Planck Institute for Evolutionary Anthropology