The Neanderthals may have become extinct because of their isolated lifestyle

In recent years, researchers have offered different explanations for why modern humans survived and the Neanderthals became extinct some 40,000 years ago.

A new study from the Globe Institute at the University of Copenhagen supports one of the main hypotheses. The researchers behind the new study discovered Neanderthal remains of a male in a cave in southern France, and the discovery supports the hypothesis that the Neanderthals may have gone extinct because of their antisocial lifestyle.

“When we look at these genomes from Neanderthals, we see that they are quite inbred and therefore don’t have much genetic diversity. They have been living in small groups for many generations. We know that inbreeding reduces genetic diversity in a population, which can be detrimental to their ability to survive if it occurs over a longer term,” one of the researchers behind the new study, Associate Professor Martin Sikora from the Globe Institute, explains and adds:

 “The newly found Neanderthal genome is from a different lineage than the other late Neanderthals previously studied. This supports the notion that social organization of Neanderthals was different to early modern humans who seemed to have been more connected.”

In other words, compared to the Neanderthals, early modern humans were more likely to connect with other groups, which is an advantage if you want to survive.

They have been living in small groups for many generations. We know that inbreeding reduces genetic diversity in a population, which can be detrimental to their ability to survive if it occurs over a longer term

“This is in the more speculative end, but even just the notion of being able to communicate more and exchange knowledge is something humans do that Neanderthals to some extend might not have done, due to their isolated lifestyles by organizing themselves in smaller groups. And that is an important skill to have. We see evidence of early modern humans in Siberia forming so-called mating networks to avoid issues with inbreeding, while living in small communities, which is something we haven’t seen with Neanderthals,” Postdoc Tharsika Vimala says.

DNA sheds light on the history of the Neanderthals

Researchers have found little Neanderthal DNA considering the substantial number of discovered Neanderthal remains across Eurasia. Some of the oldest Neanderthal DNA dates back to 120 thousand years ago and have been recovered from Neanderthals found in the Denisova Cave (Altai Mountains) and caves in Scladina (Belgium) and Hohlenstein-Stadel (Germany). In fact, the “new” Neanderthal genome is merely the fifth of its kind to be found in Western Europe with an age below 50 thousand years old.

“Our team in Copenhagen extracted DNA from his tooth, sequenced the DNA and analysed his nuclear genome, which is the DNA found within the core of the cells. The DNA was analysed along with other known Neanderthal genomes to understand their shared history,” Martin Sikora says.

In addition, the researchers re-analysed the genome of another known late Neanderthal from France and found that this individual also carried ancestry from a distant Neanderthal lineage which is different from the ‘new’ genome. The findings tell us that multiple isolated communities might have been present in Western Europe up until their demise.

According to the researchers, the hypothesis is not new and has previously been found for Neanderthals living in the Altai Mountains which is naturally a more isolated area. Up until now they did not have the genomic evidence to confirm it for the Western European Neanderthals. The new discovery is therefore an important piece in the puzzle of Neanderthal history.

“It is something that we have talked about for a while. But we needed more evidence, and this is some of the evidence that we were looking for and needed to figure out how likely this hypothesis of them going extinct because of their isolated lifestyle is. We do, however, need much more genomic data to paint a better picture of their history,” says Tharsika Vimala.

The study has been published in Cell Genomics and is available here.