The recent discovery of Neanderthal remains in a cave in southern France has shed new light on why Neanderthals went extinct around 40,000 years ago. A study by scientists from the Globe Institute at the University of Copenhagen suggests that the Neanderthals’ isolated lifestyle may have contributed to their extinction, a hypothesis long debated by scientists.

Social isolation of Neanderthals

The study, which involved analysis of the remains of a Neanderthal male, supports the idea that Neanderthals may have become extinct due to inbreeding and limited social interaction. According to co-author Professor Martin Sikora, Neanderthal genomes show a pattern of inbreeding from generation to generation, which reduced genetic diversity and weakened long-term survival chances.

“When we look at these Neanderthal genomes, we see that they were highly related and therefore did not have a lot of genetic diversity. They lived in small groups for generations. We know that inbreeding reduces genetic diversity in a population and if this occurs over a long period of time, it can negatively impact survival,” explained Professor Sikora.

A new genome has been discovered

The newly discovered Neanderthal genome is different from other late Neanderthals previously studied, further supporting the theory that Neanderthals lived in small, isolated groups. In contrast, early modern humans appear to have been more socially connected, which may have contributed to their survival.

The ability to communicate and share information across groups may have been useful to early humans, especially when they formed networks that helped prevent inbreeding, as seen in Siberia.

“This is more speculative, but even the idea of ​​being able to communicate more and share information is something that humans do, which Neanderthals could not do to some extent because of their isolated lifestyle, organizing themselves into smaller groups. And that is 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; this is something we don’t see in Neanderthals.”

Limited amount of DNA

Although Neanderthal remains have been found in Eurasia, only a limited amount of their DNA has been successfully recovered. Some of the oldest known samples of Neanderthal DNA, at 120,000 years old, come from samples in the Altai Mountains of Belgium and Germany. The “new” Neanderthal genome found in France is one of five similar finds in Western Europe that are less than 50,000 years old.

“Our team in Copenhagen extracted DNA from his tooth, sequenced his DNA and analysed his nuclear genome, the DNA found in the cell nucleus. The DNA was analysed alongside other known Neanderthal genomes to understand their shared history, Sikora said.

A few isolated Neanderthal communities

The researchers also reanalyzed the genome of another late Neanderthal in France and found that it came from a different lineage than the recently discovered genome, suggesting that several isolated populations of Neanderthals coexisted in Western Europe until their extinction.

The discovery adds a key piece to the puzzle of Neanderthal history. Previous studies of Neanderthals in more remote areas, such as the Altai Mountains, have hinted at the possibility that isolation played a role in their extinction, but genomic evidence for Western European Neanderthals has been lacking until now.

“This is something we have been talking about for a long time. But we needed more evidence, and this is some of the evidence we are looking for to find out how likely it is that they went extinct because of an isolated lifestyle. But we need much more genomic data to be able to paint a better picture of their history,” Vimala said.

The study, published in the journal Cell Genomics, is an important step toward understanding the causes of Neanderthal extinction and how their isolated lifestyle contributed to it.