Disappearance Of Neanderthals: Were Inbreeding And Demographic Shifts Responsible?

Conny Waters – MessageToEagle.com – Inbreeding and population/demographic shifts could have led to Neanderthal extinction, researchers say.

Neanderthal extinction could have occurred without environmental pressure or competition with modern humans.

Neanderthals disappeared around 40,000 years ago — about the same time that anatomically modern humans began migrating into the Near East and Europe.

“Did Neanderthals disappear because of us? “No”, the study suggests. It seems that humans did not contribute to the extinction of Neanderthals.

“The species’ demise might have been due merely to a stroke of bad, demographic luck.”

In the study published in the journal PLOS ONE, researchers used data from extant hunter-gatherer populations as parameters, the authors developed population models for simulated Neanderthal populations of various initial sizes (50, 100, 500, 1,000, or 5,000 individuals).

They then simulated for their model populations the effects of inbreeding, Allee effects (where reduced population size negatively impacts individuals’ fitness), and annual random demographic fluctuations in births, deaths, and the sex ratio, to see if these factors could bring about an extinction event over a 10,000-year period.

See also:

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Mysterious Archaic Cavemen – Denisovans – Were Relatives To Neanderthals And Humans

The population models show that inbreeding alone was unlikely to have led to extinction (this only occurred in the smallest model population). However, reproduction-related Allee effects where 25 percent or fewer Neanderthal females gave birth within a given year (as is common in extant hunter-gatherers) could have caused extinction in populations of up to 1,000 individuals. In conjunction with demographic fluctuations, Allee effects plus inbreeding could have caused extinction across all population sizes modeled within the 10,000 years allotted.

The population models are limited by their parameters, which are based on modern human hunter-gatherers and exclude the impact of the Allee effect on survival rates. It’s also possible that modern humans could have impacted Neanderthal populations in ways that reinforced inbreeding and Allee effects but are not reflected in the models.

However, by showing demographic issues alone could have led to Neanderthal extinction, the authors note these models may serve as a “null hypothesis” for future competing theories — including the impact of modern humans on Neanderthals.

Written by Conny Waters – MessageToEagle.com – AncientPages.com Staff Writer