From research tools, art, and fossilized footprints, prehistoric scientists have concluded – so carefully so far – that Neanderthals lived in small groups, who were in regular contact with each other. But scientific information about society at that time is scarce. It also makes sense, when you consider that Neanderthals may have roamed the Earth for about 400,000 years, and only a little over a hundred sites are known with the remains of these people.
Only genetic analysis can provide an answer as to how the relationships between and within groups are arranged. However, DNA analyzes on these ancient remains are very difficult, and therefore rare. It is not for nothing that Svante Papau was awarded the Nobel Prize for his research into Neanderthal DNA. Eighteen Neanderthal genomes have been studied worldwide, until recently Laurits Skov and colleagues turned to the analysis of thirteen Neanderthal remains from two caves in the Altai Mountains.
Chagyrskaya Cave in the northwest of the Altai Mountains contains about 90,000 stone artifacts and the largest collection of Neanderthal remains in North Asia. Neanderthals lived there between 51,000 and 59,000 years ago, at the easternmost point of their range. Tens of kilometers away is the Okladnikov Cave, where the remains of Neanderthals were also found. The individuals in both caves were descendants of Neanderthals from Eastern Europe who migrated to Siberia.
Skov and colleagues were able to recover DNA from teeth and bones from 11 individuals from Chgerskaya Cave and two from Okladnikov Cave. Thirteen genomes seem to tell us little about eighteen years of social interactions and family relationships. But the researchers found that some of the people in the caves were closely related, and they must have been contemporaries. So the DNA analysis results in a family portrait.
In the Chagyrskaya Cave, geneticists found a father and teenage daughter, and a male relative on the maternal side. Another man and woman were second-degree relatives, and they share about 25 percent of their DNA. Genetic analyzes also indicated that all 11 members of the group in that cave are related to each other. The two people in Okladnikov Cave were not related to each other, nor to the group in Shagirskaya Cave.
Women on the go
At least, based on their DNA. Because when the researchers mapped mitochondrial DNA, they came to a more accurate conclusion. Mitochondrial DNA is inherited from your mother, and fathers do not pass it on. So parsing this results in a Family tree along the female line. The mitochondrial DNA of an individual from Okladnikov Cave was found to be identical to that of an individual from Chgerskaya Cave. According to scientists, this proves that these two consorts along the maternal line lived a maximum of a few thousand years.
It also turned out that mitochondrial DNA from two people – from a previous project – was not related to other members of the group from Chagyrskaya Cave, but to one of the individuals from Okladnikov Cave.
If scientists compare the proportions along the female line with the male line, to find out via the Y chromosome., they saw greater affinity among the males in the group than the females. Dan can have different reasons, but in this case, according to their analysis, this is due to the migration of women. Women from one group went to live with another group and had children there.
Small, closely related groups
Since both gene alleles in an individual are more similar – more similar – the parents are more closely related. In the case of the Neanderthals in the Chgerskaya Cave, the researchers found that nearly 20 percent of the genome was completely homologous. If this is the case with an individual, they write, then the parents will be second-degree related, to a group of unrelated members.
Since these large portions of alleles are identical across all members of the group, they concluded that the entire group is closely related. This is the case for a small group of people in small groups in a sparsely populated area. The researchers also applied a model to their results. This found the best agreement with groups of about twenty people, with sixty to one hundred percent of the women belonging to another small group.
The authors themselves point out that their research offers little more than a snapshot of Neanderthal existence. But new discoveries and improved technologies should allow more family photos to be taken. We hope that the album containing the life history of our closest relatives will have fewer blank pages.
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