Ancient DNA reveals the first Neanderthal family portrait

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Meet the Neanderthals of Chagyrskaya Cave.

The riverside hunting camp in the foothills of the Altai Mountains in Siberia was home to a close-knit community of some 20 inhabitants some 54,000 years ago, including a father and his teenage daughter, a young man who might have been a nephew or a cousin of theirs. , and an adult second-degree relative, perhaps an aunt or grandmother.

The girl would probably have distanced herself from her father and the family group when she found a partner. If she had been a child, like her young cousin, she probably would have stayed where she was. However, the communities to which she migrated would likely have had familiar faces.

These are some of the intimate details of Neanderthal family and social life revealed by a study of ancient DNA belonging to 11 former residents of Chagyrskaya Cave, as well as the remains of two others from nearby Okladnikov Cave.

It’s the oldest known family group and the first time scientists have been able to directly document the fabric of a Neanderthal family and community, making our ancient cousins ​​look much more human.

“The fact that they were living at the same time is very exciting. This means that they probably come from the same social community. So, for the first time, we can use genetics to study the social organization of a Neanderthal community,” study co-author Laurits Skov, a researcher at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, said in a news release. (“Neanderthal” is an alternative German spelling.)

The researchers extracted DNA from 17 bones and teeth that once belonged to seven male and six female Neanderthals, eight of whom were adults and five children.

They were able to unravel multiple strands of genetic ancestry: mitochondrial DNA, which follows the maternal line; Y chromosome DNA, which is inherited through the male line; and nuclear DNA.

In mitochondrial DNA, the researchers found several heteroplasmies, distinctive genetic signatures that only persist for a small number of generations, that were shared among individual Neanderthals. This phenomenon, the researchers said, suggested that the Neanderthals they studied at Chagyrskaya cave must have lived and died at roughly the same time.

They also found that the genetic diversity of Y-chromosome DNA was much less than that of mitochondrial DNA, which is passed down from mothers. The study calculated that, in this group, two male individuals could expect to share an ancestor around 450 years before living. By contrast, the equivalent estimate for female individuals was around 4,350 years.

The researchers said the best explanation for this was that more than 60% of female Neanderthals in the small group Chagyrskaya had emigrated from another community. This social structure is common among present-day hunter-gatherer societies and is known as patrilocality.

More generally, the community had extremely low genetic diversity, much lower than that recorded for any ancient or current human community, according to the study. The level of diversity was more similar to the size of groups of endangered species on the verge of extinction, such as mountain gorillas, which have a population of around 1,000.

However, Chris Stringer, research leader in human evolution at the Natural History Museum in London, who was not involved in the research, said a lack of genetic diversity was not necessarily a significant factor in the extinction of Neanderthals, who disappeared. around 40,000 years ago. He said other Neanderthal sites that were active around the same time as the studied group, such as Vindija in Croatia, indicate larger and more diverse populations.

The study authors said that the family group they had discovered might not be representative of the social life of the entire Neanderthal population. They recommended future research that includes genetic sequencing of more Neanderthal individuals and communities.

The inhabitants of the two caves probably interacted, walking to the same rock sources to make their stone tools, supporting the genetic link between them. Neanderthals hunted mountain goats, horses, bison, and other animals that traveled through the river valleys that overlook the caves.

Chagyrskaya and Okladnikov are 100 kilometers (62 miles) from Denisova Cave, one of the most important places in the study of human evolution. That site was occupied by Neanderthals, early modern humans, and Denisovans, a more recently identified type of extinct human that was discovered from DNA extracted from a single little finger.

Svante Pääbo, another co-author of the Chagyrskaya study, sequenced the first Neanderthal genome in 2010, work for which he received the Nobel Prize earlier this month. Since that initial sequencing, genome-wide data has been recovered from a total of 18 Neanderthals. The new study adds another 13, a major technical achievement, said Lara Cassidy, an assistant professor in the Department of Genetics at Trinity College Dublin, who was not involved in the research.

“What makes this work particularly remarkable is that the sequenced individuals are not scattered across the vast expanse of Neanderthal existence, but are concentrated at a specific point in time and space, providing the first snapshot of a family group,” he said in a comment published along with the study.

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