‘A major disruption in Neanderthal history’: 65,000 years ago, all but one lineage of European Neanderthals became extinct

Neanderthals experienced a cataclysm before going extinct, resulting in only one genetic lineage surviving in Europe and then spreading across the continent, a new study shows.

The findings, published March 23 in the journal PNAS, may shed light on what ultimately led to Neanderthals’ demise.

Neanderthals are one of the closest relatives of modern humans (Homo sapiens), and their lineage diverged about 500,000 years ago. Neanderthals once lived throughout Eurasia, but are generally thought to have become extinct about 40,000 years ago.

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DNA recovered from Neanderthal fossils could reveal not just the extinction of Neanderthals, but their history in general. In the new study, researchers looked at the mitochondrial DNA in cells, which helps the body produce energy and is passed from mother to offspring.

Researchers collected 10 Neanderthal mitochondrial DNA sequences from six archaeological sites in Belgium, France, Germany, and Serbia. They analyzed them in parallel with 49 Neanderthal mitochondrial DNA sequences published in a previous study.

The researchers found that in Europe, where Neanderthals eventually became extinct, some mitochondrial DNA lineages existed until about 65,000 years ago. From this point on, these groups were replaced by a single Neanderthal mitochondrial genetic lineage originating from southwestern France. These “late Neanderthals” dispersed throughout Europe.

“This tells us that there was a great deal of confusion in the history of Neanderthals,” study lead author Cosimo Poth, a paleogeneticist at the University of Tübingen in Germany, told Live Science. “There really was a genetic change.”

Poss pointed out that glaciers began to dominate Europe about 75,000 years ago.

“We do not believe that our findings suggest that Neanderthals migrated to the Mediterranean,” he said. “While we think that Neanderthal populations in northern Europe were extinct, Neanderthal populations that were already in southwestern France survived this climate change and subsequently expanded over larger areas. Neanderthals had previously experienced multiple ice ages, but the last one proved to be harsh for survival.”

The study also found that “there was a kind of genetic poverty among late Neanderthals,” Poss said. “Because they seemed to emerge from this single group, their overall genetic diversity was much reduced compared to before. They were very similar at the genetic level across Europe, from Spain to the Caucasus to northern Europe.”

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This low genetic diversity was most pronounced about 42,000 years ago, just before Neanderthals generally went extinct, and “may have contributed to Neanderthal extinction,” Post said. “We believe there is no single reason why Neanderthals went extinct, but the lack of genetic diversity would have made Neanderthals less able to withstand climate change and other perturbations.”

Similarly, Neanderthal populations in Siberia’s Altai Mountains were more closely related to each other than to European Neanderthals, and these Siberian Neanderthals also had low genetic diversity and lived in small, isolated groups, a separate study published March 23 in the journal PNAS found.

Despite this low genetic diversity, late Neanderthals in Europe appeared to be highly diverse from site to site in terms of artifacts and art. “It is therefore likely that later Neanderthal groups were less connected to each other after Neanderthals re-expanded across Europe,” Post said. “Not only would this have resulted in more inbred groups, explaining the lower genetic diversity, but it would also have resulted in more cultural and archaeological diversity, since these groups were isolated and would have developed a more specialized culture.”

“We’ve seen evidence that Neanderthal populations replaced each other, and this paper really builds the fundamental story of why that happens, because Neanderthals always went extinct in places, and then other Neanderthal groups invaded and recolonized the same places,” Fernando Villanea, a population geneticist at the University of Colorado Boulder who was not involved in the study, told Live Science.

Future studies could try to test these findings by analyzing DNA from Neanderthal cell nuclei instead of mitochondria, Poss said. However, this will be a major challenge because there is hundreds of times less DNA from the nucleus than from the mitochondria inside the cell.

Neanderthal quiz: How much do you know about our closest relatives?