Low fertility and the demise of the Neanderthals

Shannon Roberts
June 23, 2019
Reproduced with Permission
Demography is Destiny

As fertility plummets around the world, could the fate of the Neanderthals be a warning to us?

The Neanderthals were the only human population living in Europe before the arrival of Homo sapiens, and why they died out has been debated for decades. A new study published in the journal Plos One suggests that the reason they are not around today could simply be the result of a slight decline in fertility.

Senior study author, Silvana Condemi, a paleoanthropologist at Aix-Marseille University in Marseille, France, told Live Science:

"The disappearance of the Neanderthal population is an exciting subject - imagine a human group that has lived for thousands of years and is very well-adapted to its environment, and then disappears.

...Very quickly, we found something unexpected - this disappearance, which occurred over a very long period, cannot be explained by a catastrophic event."

The study concludes that a decrease in the fertility rate of young Neanderthal women could have had a significant impact on the population, and that this simple and non-catastrophic event is a plausible explanation for Neanderthal extinction. The Neanderthal population could have simply slowly and gradually decreased over time.

The difference between "stable" fertility values and fertility values which brought about absolute demise was minimal, say the authors, but large enough to bring about the disappearance of the Neanderthals over a period of between 10,000 and 4,000 years.

We showed that, in the long run, a slight change in the fertility rate of younger females could have had a dramatic impact on the growth rate of the Neanderthal metapopulation and thus on its long-term survival.

Our modelling suggests that it is not necessary to explain the decrease in size of the Neanderthal population on the basis of catastrophic causes (diseases, extreme climatic events, and disasters such as volcanic eruptions. . . .) or even of the direct or indirect intervention of sapiens.

Senior study author, Silvana Condemi, notes:

"This is a phenomenon that is limited in scope that, over time, had an impact.

If the average number of births falls to a level of 1.3 among the women of the world, our species would disappear in 300 years. This is an unlikely model, but the results would be very rapid!"

The recent decline of our own fertility rate is one of the most fundamental social changes in human history, and it has happened very rapidly, as illustrated by the following chart: https://www.mercatornet.com/demography/view/low-fertility-and-the-demise-of-the-neanderthals/22582

The list of countries with fertility rates now below just 1.6 children per woman is a long one, and the general trend is down. It includes:

The list of countries with fertility below the generally agreed replacement rate of 2.1 children per woman is even longer. This study illustrates that who is having babies can quite quickly turn our world, countries, cultures, politics - and even our very existence - around.