The extinction of Neanderthals has been largely blamed on the superior competition of Homo sapiens.  New scientific evidence suggests that this may not the case, but natural fluctuations in birth and death rates linked together with interbreeding could have been what led to the Neanderthal extinction.

Within recent years, much evidence has pointed to the fact that Homo sapiens may not be as superior as previously thought and were very much similar to Neanderthals. As one of our most closely related extinct species, they had similar brains to us and developed stone tools and painted jewellery, developing a rich culture within their communities. It’s widely believed that Neanderthals led a predominantly hunter-gather lifestyle, whereas eventually Homo sapiens produced food through agriculture and domestication.

The Neanderthal extinction occurred around 40,000 years ago, with the Homo sapiens migrating to Europe and the Middle East 20,000 years earlier. Around this time the Neanderthal population was very small, between 10,000 to 70,000. Evidence of inbreeding between Neanderthals and Homo sapiens can be seen within the genomes of modern humans. It is estimated that in modern humans of European or Middle Eastern descent, around 2% of the genome comes from Neanderthals and humans are likely to have a direct Neanderthal ancestor of the 2000th degree. Current research suggests that interbreeding alone could not have wiped out the Neanderthals and may just have been bad luck.

To model how the population of Neanderthals and Homo sapiens may have lived over the 10,000 years before their extinction, three factors were considered: interbreeding, Allee effect, and natural fluctuations. Interbreeding with Homo sapiens harms population fitness. Allee effects (named after Dr Warder Clyde Allee) prevent small populations from thriving due to limited mate choice and not having enough individuals to raise the group’s children or hunt and protect food. Natural fluctuations in birth rates, death rates, and sex ratios also could have played a role. The model suggested that all these factors together are what could have caused the Neanderthal extinction and not just interbreeding alone, as previously thought.

The model used to demonstrate how the two species may have lived before the Neanderthal extinction was largely based on modern human populations. However, Neanderthals are biologically different from modern humans and further research will be carried out with an aim to fully understand the causes of the extinction.

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