Researchers from France propose a new hypothesis on how the Neanderthals went extinct. Their new study suggests that the Neanderthals may have disappeared because of a slight drop in their fertility rates.

Extinction Of The Neanderthals

Neanderthals, the closest extinct relatives of modern humans, disappeared about 40,000 years ago.

Scientists, however, have long debated on what really helped kill them off. For a long time, it was thought that the encounters between the Neanderthals and the Homo sapiens were to blame, but genetic analyses revealed that the interaction between the two species were not cruel and interbreeding even took place.

Computer Models Explore Disappearance Of Neanderthals

In a new study, paleoanthropologist Silvana Condemi, from Aix-Marseille University, and colleagues investigated how the Neanderthals may have disappeared by generating computer models that explored how the population of the extinct species may decline and go extinct over time in response to a range of factors, which include epidemics, war, reduced fertility rate, and survival rates.

"We used demographic modeling and simulations to identify the set of plausible demographic parameters of the Neanderthal population compatible with the observed dynamics, and to explore the circumstances under which they might have led to the disappearance of Neanderthals," the researchers wrote in their study.

Slight Drop In Fertility Rates Could Be To Blame

The results suggested that the disappearance of the Neanderthals were not due to a catastrophic event.

Computer models that assumed modern humans killed off the Neanderthals directly through war, or indirectly via an epidemic, revealed that that these factors could have decimated the Neanderthals more rapidly.

The researchers also found that increase in juvenile or adult survival as well as strong reduction in fertility rates were not the likely causes for the long decline in Neanderthal population.

The researchers instead found that the most plausible explanation is the slight drop of fertility rates. Computer models suggested that the extinction of the Neanderthals was possible within 10,000 years when the fertility rates of young Neanderthal women decreased by 2.7 percent. Extinction was possible within 4,000 years when the same group saw an 8 percent decrease in fertility rates.

"The disappearance of the Neanderthals was probably due to a slight decline in the fertility among the youngest women," Condemi said. "This is a phenomenon that is limited in scope that, over time, had an impact."

The findings were published in the journal PLOS ONE on May 29.

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