Over the past nine years, researchers have been excavating the remains of a Neanderthal from an archaeological site called Grotte Mandrin in southern France. They nicknamed him “Thorin” after a dwarf character from The Hobbit by J.R.R. Tolkien.
Now, a new analysis of Thorin’s ancient DNA has revealed that he may belong to a previously unknown lineage of Neanderthals that was isolated for 50,000 years. This lineage lived in isolation even though other members of their species were nearby.
Scientists used a root fragment from one of Thorin’s molars, enabling them to create a whole-genome sequence and find evidence of inbreeding.
Thorin was associated with a small group of Neanderthals who lived between 42,000 and 50,000 years ago. He appeared to have lived at the more recent end of that range.
However, his DNA resembles that of an older group that branched off from the main Neanderthal population about 105,000 years ago. The group remained isolated for the next 50,000 years after diverging from the other Neanderthals.
“How can we imagine populations that lived for 50 millennia in isolation while they’re only two weeks’ walk from each other?” said Ludovic Slimak, a co-author of the study and an archaeologist from France’s National Center for Scientific Research and Paul Sabatier University in Toulouse. “All processes need to be rethought.”
It is unclear what led to the group’s isolation, but it’s a possibility that their separation contributed to the extinction of Neanderthals around 40,000 years ago.
According to Tharsika Vimala, study co-author and a geneticist at the University of Copenhagen, inbreeding in isolation would’ve made the group more vulnerable.
Their genetic diversity would’ve been reduced, so they would have less of an ability to adapt to changing environments.
david hughes – stock.adobe.com – illustrative purposes only
Some Homo sapiens interbred with Neanderthals after arriving in Europe. That is why modern humans of non-African ancestry have one to four percent Neanderthal DNA.
The researchers did not find any evidence of Thorin’s group interbreeding with Homo sapiens at all.
Apparently, the isolated Neanderthals were happy to stick to one location. Meanwhile, the Homo sapiens were exploring, sharing knowledge, and building a social network.
The findings suggest that Neanderthals in Europe were not one homogenous group when they went extinct. Instead, they were at least two distinct populations.
The lack of genetic diversity combined with the arrival of Homo sapiens likely pushed the Neanderthals closer to their demise.
Furthermore, the DNA analysis indicated that there was a third “ghost” population of Neanderthals existing in Europe at the same time as Thorin’s group.
The third population was previously unknown to scientists, and they hope to learn more about it. Perhaps other small groups of Neanderthals existed on the continent.
Overall, the findings challenge the long-held belief that Neanderthals were all from the same genetically similar population.
The study was published in the journal Cell Genomics.
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