Isolation may have led to extinction
A new study supports the idea that Neanderthals likely went extinct because of how they lived — in isolation.
The early human species were anti-social, which could be what led to their demise, according to the study by researchers at the University of Copenhagen's Globe Institute. It was published in the science journal Cell Genomics on Sept. 11. Neanderthals went extinct roughly 40,000 years ago and many scientists have tried to pinpoint why. A widely accepted theory is that they remained isolated; however, evidence was lacking to confirm the theory for Western European Neanderthals until now.
The results from the recently published study suggested there were multiple isolated Neanderthal communities in Europe around the time they went extinct. They had “limited, if any, level of interactions between different Neanderthal populations in their last millenniums, even though these populations were geographically very close to each other.” The study is based on the discovery of the remains of a male Neanderthal, nicknamed Thorin, in a cave in southern France in 2015. Thorin is the most complete Neanderthal individual found in France since 1979, researchers said. Thorin was part of a small group living at the Grotte Mandrin, a French rock shelter overhanging the Rhône River Valley. The group did not have any genetic crossover with other known European Neanderthals, despite their proximity, according to the study.
“When we look at these genomes (a complete set of DNA) 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,” said Globe Institute associate professor Martin Sikora in a news release. He was one of the researchers of the study.
“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.”
Unlike modern humans, who are more connected, the results from analyzing Thorin “supports the notion that social organization of Neanderthals was different to early modern humans,” said Sikora.
There is evidence of early modern humans in Siberia “forming so-called mating networks to avoid issues with inbreeding, while living in small communities,” said another researcher from the University of Copenhagen Tharsika Vimala. But that behaviour was not found among Neanderthals.
“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,” said Vimala.