The recent discovery of Neanderthal remains in a cave in southern France has provided new insight into why Neanderthals went extinct about 40,000 years ago. The study, conducted by scientists from the Globe Institute at the University of Copenhagen, suggests that the isolated lifestyle of Neanderthals may have contributed to their extinction, a hypothesis that has long been considered by scientists.
Social isolation of Neanderthals
The study, which included an analysis of the remains of a Neanderthal man, supports the idea that Neanderthals may have gone extinct due to inbreeding and limited social interaction. According to Prof. Martin Sikora, one of the study’s authors, Neanderthal genomes show a pattern of intergenerational inbreeding that reduces their genetic diversity and weakens their chances of long-term survival.
“When we look at these Neanderthal genomes, we see that they are quite inbred and therefore do not have much genetic diversity. They lived in small groups for many generations. We know that inbreeding reduces the genetic diversity in a population, which can negatively affect its ability to survive if it occurs over time,” explained Prof. Sikora.
New gene discovered
The newly discovered Neanderthal genome differs from other late Neanderthals studied previously, further supporting the theory that Neanderthals lived in small, isolated groups. In contrast, early modern humans seem to have been more socially connected, which may have contributed to their survival.
The ability to communicate and share knowledge between groups would have been beneficial for early humans, especially when they formed networks that helped prevent inbreeding, as was seen in Siberia.
“It’s more speculative, but even the idea of being able to communicate more and share knowledge is something that humans do that Neanderthals to some extent couldn’t do because of their isolated lifestyle, organizing themselves into smaller groups. And that’s a very important skill,” says study co-author Tharsika Vimala, a doctoral student at the University of Copenhagen.
“We see evidence that early modern humans in Siberia formed so-called mating networks to avoid inbreeding problems by living in small communities, something we have not seen in Neanderthals.”
Limited amount of DNA
Although Neanderthal remains have been found throughout Eurasia, only a limited amount of their DNA has been successfully recovered. Some of the oldest known Neanderthal DNA samples, which are 120,000 years old, have been recovered from samples in the Altai Mountains, Belgium, and Germany. The “new” Neanderthal genome from France is one of five such finds in Western Europe that are less than 50,000 years old.
“Our team in Copenhagen extracted DNA from his tooth, sequenced the DNA and analyzed his nuclear genome, which is the DNA found in the nucleus of cells. The DNA was analyzed along with other known Neanderthal genomes to understand their shared history,” Sikora explained.
Several Neanderthal communities in isolation
The researchers also re-analyzed the genome of another late Neanderthal from France and found that it came from a different lineage than the newly discovered genome. This suggests that several isolated communities of Neanderthals coexisted in Western Europe until their extinction.
This discovery adds an important piece to the puzzle of Neanderthal history. Previous research on Neanderthals in more remote regions, such as the Altai Mountains, had already hinted at the possibility that isolation played a role in their extinction, but there was no genomic evidence for Western European Neanderthals until now.
“This is something we have been talking about for a long time. But we needed more evidence, and these are some of the things we’ve been looking for to find out how plausible the hypothesis is that they went extinct because of their isolated lifestyle. However, we need a lot more genomic data to paint a better picture of their history,” Vimala said.