The first genetic analysis of a Neanderthal family paints a fascinating picture of a close-knit community

Our closest evolutionary relatives, the Neanderthals (Homo neanderthalensis), were once widespread throughout Europe and as far away as the Altai Mountains in southern Siberia.

Yet more than 160 years since the first Neanderthal fossils were unearthed in Europe, little is known about the group size or social organization of Neanderthal communities.

Using ancient DNA, a new study provides a snapshot of a Neanderthal community frozen in time.

With our colleagues, we show that a group of Neanderthals living in the Altai foothills about 54,000 years ago consisted of perhaps 10-20 individuals. Many of them were closely related, including a father and his young daughter.

The most eastern Neanderthals

The first genetic clues about Neanderthals have been obtained 25 years ago from a fragment of mitochondrial DNA, which is found in cellular structures called mitochondria rather than the cell nucleus.

Subsequent studies of mitochondrial DNA and genome-wide nuclear data from 18 individuals sketched the broad strokes of Neanderthal history, revealing the existence of many genetically distinct groups between approximately 430,000 and 40,000 years ago.

Our new study is the first to analyze ancient DNA from the teeth and bones of multiple Neanderthals who lived around the same time. The fossils came from archaeological excavations of Okladnikov Cave in the mid-1980s and Chagyrskaya Cave since 2007.

These caves were used by Neanderthals as hunting camps. The remains of animals such as bison and horses are plentiful, and more than 80 Neanderthal fossils have also been found in Chagyrskaya Cave, one of the largest collections of its kind in the world.

Both sites also contain distinctive stone tools which bear a striking resemblance to artifacts found at Neanderthal sites in central and eastern Europe.

To paint a detailed picture of the genetic makeup and parentage of these Neanderthals, we analyzed mitochondrial DNA (which is passed down in the female line), Y chromosomes (passed down from father to son), and whole genome data (inherited from both parents) for 17 Neanderthal fossils, the most ever sequenced in a single study.

The teeth and bones came from 13 individuals: 11 from the Chagyrskaya cave and two from the Okladnikov cave. Seven of the Neanderthals were male and six female. Eight were adults and five were children or adolescents.

Among them were the remains of a Neanderthal father and his teenage daughter, as well as a pair of second-degree relatives: a boy and an adult woman, possibly his cousin, aunt, or grandmother.

Although the nearby site of Denisova Cave was inhabited by Neanderthals as early as 200,000 years ago, the Chagyrskaya and Okladnikov Neanderthals are more closely related to European Neanderthals than to the earlier ones from Denisova Cave.

This result is consistent with a previous genomic study of a Chagyrskaya Neanderthal and the presence of distinctive stone tools at Chagyrskaya and Okladnikov Caves that closely resemble those found at Neanderthal sites in Europe.

We also found that the Chagyrskaya Neanderthals share several heteroplasmies, a special type of mitochondrial DNA variant that typically persists for less than three generations.

Taken together with evidence of their close family ties, these indicate that the Chagyrskaya Neanderthals must have lived – and died – at about the same time.

On the verge of extinction

Our analyzes also revealed that this Neanderthal community had extremely low genetic diversity, consistent with a group of just 10-20 people.

This is much smaller than the genetic diversity recorded for any ancient or current human community, and is more similar to that found among endangered endangered species, such as mountain gorilla.

However, the Chagyrskaya Neanderthals were not a hermit community. We found that their mitochondrial DNA diversity was much higher than their Y chromosome diversity, which may be explained by the predominance of female (rather than male) migration among Neanderthal communities.

Did these migrations involve Denisovans, who repeatedly occupied Denisova Cave from at least 250,000 years ago to about 50,000 years ago?

Denisovans are a sister group to Neanderthals and have interbred at least once. This happened about 100,000 years ago, produce a daughter from a Neanderthal mother and a Denisovan father.

However, even though Denisovans were present in Denisova Cave at about the same time as Neanderthals living in Chagyrskaya and Okladnikov Caves, we found no evidence of Denisovan gene flow in these Neanderthals in the 20,000 years that preceded their disappearance. .

Kindred spirits

In recent years, multiple lines of evidence have shown that Neanderthals were possessed technical skills, cognitive abilities And symbolic behaviors impressive as those of our ancient homo sapiens ancestors.

Our genetic insights add a new social dimension to this picture. They provide a rare glimpse into the close-knit family structure of a Neanderthal community eking out an existence on their geographic range’s eastern frontier, close to the time their species finally became extinct.

Laurits Skov is a postdoctoral research associate at the Max Planck Institute for Evolutionary Anthropology. Richard ‘Bert’ Roberts is the director of the ARC Center of Excellence for Australian Biodiversity and Heritage (CABAH) at the University of Wollongong. This article was republished by The conversation under a Creative Commons license. Read the original article.

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