Researchers reveal the first Neanderthal family in largest known genetic study
Researchers undertook the largest known genetic study of Neanderthals reported to date and revealed new insights into the social organization of Neanderthals. Based on an analysis of the ancient DNA of 13 Neanderthal individuals from two caves in Siberia, the researchers provided the "first known description" of the relationships of a small community of Neanderthals.
Their findings were published Wednesday in Nature.
Neanderthals occupied western Eurasia until about 430,000 to 40,000 years ago. Researchers published the first Neandertal draft genome in 2010. Even though experts from the Max Planck Institute for Evolutionary Anthropology have sequenced a further 18 genomes from 14 different archaeological sites throughout Eurasia, little is known about their social organization.
To examine further the social structure of the group, the researchers set forth to southern Siberia, a region known for ancient DNA research such as the Denisovan hominin remains at the famous Denisova Cave - which revealed that Neanderthals and Denisovans lived and interacted with each other.
The largest number of Neanderthal remains ever sequenced
Within 62 miles (100 kilometers) of the Denisova Cave lie the Chagyrskaya and Okladnikov Caves. The Neanderthals had occupied these sites briefly around 54,000 years ago - their remains were previously recovered from deposits. For their new study, researchers retrieved DNA from 17 Neandertal remains, which is the largest number of Neanderthal remains ever sequenced in a single study.
The authors found a special kind of genetic variant called heteroplasmies in the mitochondrial DNA of the 17 remains that came from 13 Neandertal individuals – seven men and six women. This indicated that some Chagyrskaya individuals were closely related, including a father and his teenage daughter, among a pair of second-degree relatives. The combination of heteroplasmies and related individuals suggested that the Neandertals in Chagyrskaya Cave "must have lived – and died – at around the same time".
"The fact that they were living at the same time is very exciting. This means that they likely came from the same social community. So, for the first time, we can use genetics to study the social organization of a Neandertal community," Laurits Skov, the first author of this study, said in a statement.
The Neanderthal communities were linked by female migration
The gene sleuths also noted the "extremely low genetic diversity" within this Neanderthal community which was consistent with a group size of 10 to 20 individuals. "This is much lower than those recorded for any ancient or present-day human community and is more similar to the group sizes of endangered species on the verge of extinction," as per the per release.
Another significant finding was that the genetic diversity of Y chromosomes (passed down the males) was notably "lower than the mitochondrial DNA", which is passed from mothers, in these individuals. This suggested that females were more likely to migrate than males and that Neanderthal communities were primarily linked by female migration.
"Our study provides a concrete picture of what a Neandertal community may have looked like," said Benjamin Peter, the last author of the study. "It makes Neandertals seem much more human to me."
The researchers stress that the sample size is small and may not represent the social lives of the whole Neanderthal population.
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