One of the DNA of the last Neanderthal could explain the extinction of the species

The mystery surrounding one of the last Neanderthals

Tens of thousands of years ago, a Neanderthal nicknamed Thorin lived in southeastern France, not long before his species became extinct.

His remains were first discovered in 2015 and sparked a debate between archaeologists, who dated it between 50,000 and 42,000 years old, and geneticists, who insisted its DNA showed it was closer to 100,000 years.

The discrepancy launched a seven-year investigation that culminated in a recent study in which geneticists looked at a handful of Neanderthal DNA from around the world and compared it to Thorin’s DNA, starting from on the assumption that it was 50,000 years old instead of 100,000.

“At this point, geneticists decided to calibrate their own tools and change everything we knew about all Neanderthals.” archaeologist Ludovic Slimak, lead author of the new study published in Cell Genomics, told Business Insider. Namely that they were all part of one a single homogeneous population.

Because of how different his DNA was from Neanderthals closer to his age, researchers realized that Thorin must have belonged to an entirely new lineage of Neanderthals. They estimated that his ancestral line split about 103,000 years ago.

This explained why Thorin’s DNA seemed much older than his bones. His DNA resembles Neanderthals who lived more than 100,000 years ago, but Thorin was 50,000 years younger, according to the recent study.

What could have caused this genetic split? Researchers suspect that Thorin lived in an isolated community that had no contact with other groups from the time they separated until Thorin’s death.

That means, people from community reproduced among them for more than 50,000 years, gave rise to a unique lineage distinct from other Neanderthal groups, according to researchers.

As you can imagine, a community isolated for so long will inevitably lead to inbreeding, and researchers have indeed found evidence of this in Thorin’s DNA.

The community’s isolation also helps explain why Thorin was among the last Neanderthals. Inbreeding leads to a lack of genetic diversitywhich can make populations more vulnerable to disease, harmful mutations and environmental change.

While an isolated community can’t speak for an entire species, it can point to a key behavior that sheds new light on why these human relatives went extinct.

“We have this incredible extinction, which is the last great extinction of humanity,” Slimak said.

Neanderthals kept to themselves, which may help explain their extinction

Thorin’s community was not isolated by geography. They were isolated because they chose to be, Slimak said. “We are facing a border, a social border,” he said.

Actually, other Neanderthals lived only a few weeks’ walk from Thorin in the Massif Central around the same time.

If Thorin’s relatives ignored their Neanderthal neighbors, that means the group’s isolation was not just genetic, but also cultural and social, Slimak said.

“It’s something very important and very essential to understanding what this population was and ultimately why and how they disappeared and became extinct,” Slimak said.

While isolation may have worked for Thorins’ ancestors for millennia, eventually their luck ran out. “Their little social network just collapsed and died a whisper,” Slimak said.

The large social networks of modern humans may have helped them survive

How universal this isolationist behavior was among Neanderthals is not clear. If resources in the area were scarce, Neanderthals would have started to become more insular to protect their own group.

“Maybe this idea that one group kept to themselves, maybe it’s not so crazy in such a competitive environment,” said April Nowell, a Palaeolithic archaeologist at the University of Victoria, who did not was involved in the study.

As Neanderthal numbers declined, maintaining smaller and smaller groups would have put their future in jeopardy every time a family member died.

Many experts believe that small groups of Neanderthals led to their extinction, which would have made them vulnerable even without added stressors such as increased human competition.

Meanwhile, modern humans did not seem to have had the same tendency to form island communities. Instead, they traveled far and wide and formed large social networks, Slimak said.

“We see modern human populations that appear to have these wider social networks and exchange genes with potential mates over a wider geographic region,” Nowell said.

Modern human groups were expanding and becoming more genetically diverse. That made them better equipped to deal with any type of accident or natural disaster, Nowell said.

On the other hand, with smaller Neanderthal populations, even the loss of a number of reproductive-age individuals impacts future generations, she said.

“I really think genetic isolation tells us something interesting about Neanderthals and their challenges and ultimately their extinction,” Nowell said.