Researchers looked at DNA extracted from the remains of 13 Neanderthals that lived in Asia about 54,000 years ago and found some surprising relationships among them.
Neanderthals (Homo neanderthalensis) were a group of hominins that lived alongside and interbred with anatomically modern humans until their disappearance around 40,000 years ago. Recognisable for their barrel chests, stocky builds, and pronounced brows, Neanderthals are thought to have been bred out of existence; most everyone walking around today has Neanderthal DNA in their genome.
The recently studied group of Neanderthals lived in the Altai mountains, in what is now southern Russia. Seven of the group were men and six were women; based on the team’s analysis, eight were adults and five were children or adolescents.
Their remains were found in the Chagyrskaya and Okladnikov caves, about 97 km from the famous Denisova Cave (so-named for the discovery of Denisovan remains on the site). An analysis of DNA from the bones and teeth — the most ever sequenced in a single study — is published this week in Nature.
“The fact that they were living at the same time is very exciting. This means that they likely came from the same social community,” said Laurits Skov, a researcher at the Max Planck Institute for Evolutionary Anthropology and the study’s lead author, in an institute release. “For the first time, we can use genetics to study the social organisation of a [Neanderthal] community.”
The researchers found that some individuals from Chagyrskaya Cave were closely related. There was a father and daughter, as well as a pair of second-degree relatives: a young boy and, based on the age and sex of the other individual when she died, a cousin, aunt, or grandmother.
Denisova Cave was occupied by Neanderthals and Denisovans roughly at the same time that Neanderthals lived in Chagyrskaya Cave. Despite the proximity of the two caves, the difference in stone artifacts and the genetic evidence indicate that, in the 20,000 years before the Chagyrskaya Neanderthals lived, Denisovans did not breed with the ancestors of the Chagyrskaya Neanderthals.
Mitochondrial DNA taken from individuals in Chagyrskaya and Okladnikov caves did indicate that there was some ancestral connection between the communities occupying those sites.
The team also compared the genetic diversity from the Neanderthals’ Y chromosomes (which is inherited from father-to-son) with the diversity from the mitochondrial DNA, which is matrilineal. Based on the shared variants in the individuals’ DNA, the team posits that Neanderthals like those in Chagyrskaya and Okladnikov caves were mainly linked by female migration, rather than male migration.
“To determine how communities were linked, we looked at the mitochondrial DNA (which is inherited from mother to child) and the Y chromosome (which is inherited from father to son,” Skov told Gizmodo in an email. “When we study the Chagyrskaya Neanderthals, we find that the mitochondria are very different but the Y chromosomes are similar — so this suggests that women are the mobile ones.”
Perhaps most fascinating aspect of the work, though, is the closeness of connections between individuals found at the same place. It is not astonishing that Neanderthal kin would stick together, but it is special thing to see that proximity manifest in the remains found at a single site.
As more genetic evidence is found and ancient DNA analysis techniques improve, we’ll only learn more about how these ancient human relatives lived.