Declining fertility rates may have driven Neanderthals to extinction: Study

A small decline in the fertility rates of young Neanderthals may have caused the archaic human species to go extinct, a study claims.

The research, published in the journal PLOS ONE, used population modelling to put forward a new hypothesis for Neanderthal extinction.

The lack of empirical data allowing testing of hypotheses is one of the biggest challenges for researchers studying Neanderthal extinction. Many hypotheses involve catastrophic events such as disease or climate change.

In order to test alternative hypothetical extinction scenarios, researchers from Aix Marseille Universite in France created a Neanderthal population model allowing them to explore demographic factors which might have resulted in declining populations and extinction over a period of 4,000-10,000 years.

The researchers created baseline demographic parameters for their Neanderthal extinction model based on observational data on modern hunter-gatherer groups and extant large apes, as well as available Neanderthal paleo-genetic and empirical data from earlier studies.

They defined populations as extinct when they fell below 5,000 individuals.

Researchers saw that in their model, extinction would have been possible within 10,000 years with a decrease in fertility rates of young (less than 20 year-old) Neanderthal women of just 2.7 per cent.

If the fertility rate decreased by eight per cent, extinction occurred within 4,000 years. If this decrease in fertility was amplified by a reduction in survival of infants, a decrease in survival of just 0.4 per cent could have led to extinction in 10,000 years.

The study is the first to use empirical data to suggest that relatively minor demographic changes, such as a reduction in fertility or an increase in infant mortality, might have led to Neanderthal extinction.

The research does not attempt to explain "why" the Neanderthals disappeared, researchers said, but to identify "how" their demise may have taken place.

The results suggest that a very small reduction in fertility may account for the disappearance of the Neanderthal population.

According to this research, this decrease did not concern all female Neanderthals, but only the youngest.