50,000-year-old DNA reveals first-ever look at Neanderthal family
Fragments of bones and teeth located in a cave in the snowy Siberian Altai Mountains have revealed the first ever glimpse of a Neanderthal family. More than 50,000 years ago, a group of adults and children died hiding in their hunting camp, and the find gives archaeologists and geneticists the most complete set of Neanderthal genomes to date.
About 60 miles (100 kilometers) west of Denisova Cave, which yielded evidence of an extinct hominin species called Denisovans a little more than ten years ago, the Chagyr Cave was located, where in 2019 excavators were found (opens in a new tab) about 90,000 stone artifacts, bone tools, animal and plant remains, and 74 Neanderthal fossils. Organic remains of the Chagyr Cave, which is believed to have been a short-term bison hunting camp radiocarbon 51,000 to 59,000 years old. Pollen and remains of animals show that during the short time when Neanderthals inhabited Chagyrskaya, the climate was quite cold.
The new analysis was published on October 19 in the journal Nature (opens in a new tab) delves into the genetic composition of Neanderthals in Chagyr and the nearby Okladnikova cave. The study revealed a staggering 13 genomes, nearly doubling the number of complete Neanderthal genome sequences in existence. While previous work estimated the size of Neanderthal communities based on footprints and patterns of site use, the new genomic analysis directly tested the hypothesis that Neanderthals lived in biologically connected groups of 20 or fewer individuals.
On the subject: Neanderthals and humans were much more connected than anyone thought
Genetic data of 11 Neanderthals found in the Chagyr Cave provided researchers with the first indisputable evidence of Neanderthal family relationships, the article says. The DNA from two individuals—an adult male and an adolescent female—suggested a “first-degree relationship,” meaning they could be mother and son, brother and sister, or father and daughter.
But their mismatched mitochondrial DNA (mtDNA), which is usually passed down from mother to child, ruled out the first two pairs, bringing researchers face-to-face with a father and his teenage daughter. The father also shared mtDNA with two other males who were likely close maternal relatives; “for example, they could divide the grandmother,” the authors suggest.
There is no evidence that these wandering Neanderthals intermingled with the neighboring Denisovans, even though they were probably in the same place at the same time. The researchers write that they estimate that the Denisovans shared a common ancestor, perhaps 30,000 years before the Chagyr Neanderthals existed, and that the Chagyr and Okladnikov individuals “appear to be equally related to European Neanderthals and were part of the same Neanderthal population.”
The high similarity in the genome segments of these Neanderthals also led the researchers to “conclude that the size of the local Chaghir Neanderthal community was small.” Fitting the models to mtDNA and Y-DNA, the latter of which is passed from fathers to sons, the best scenario “assumes a community size of 20 individuals,” with female migration being “a major factor in the social organization of the Chagyr Community of Neanderthals,” the study authors write. In fact, some women remained in the group they were born into, while many others left their communities to join new ones. But the researchers are not sure if this group size can be applied outside the Altai region, as the Chagyr group could be a unique isolated example.
Isolation may have been the cause of the demise of these Neanderthals. Reflecting on the cause of the death of this group, paleogeneticist and lead author Lavrits Skow said The New York Times (opens in a new tab) that the group may have starved to death after a poor bison hunt, while geochronologist and co-author Richard Roberts said The Washington Post (opens in a new tab) that “maybe it was just a terrible storm. They are in Siberia after all.”