Our hypotheses surrounding the Neanderthals’ fate have… changed over time. The longest-standing theory is that we outcompeted them: We were smarter or stronger.
But a 2019 PLoS ONE paper posited a very different theory, which has gained significant ground among archaeologists: Neanderthals may have died out because their often-tenuous population dropped below sustainable levels — through wholly natural forces.
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Essentially, they wanted to utilize estimates of the Neanderthal population numbers to determine whether demographic factors like inbreeding, random variations in sex ratios, chance events such as floods or droughts, and difficulty finding a mate could account for the Neanderthals’ disappearance.
And according to their model, it could. The Neanderthals spent much of their existence with a population close to extinction, [author Krist] Vaesen explains. Random variations in reproductive potential and population size, combined with inbreeding reducing both fertility and survival, could sufficiently explain the disappearance of our cousins.
Perhaps humans did play some role, but it may not have been competitive, Vaesen says. If humans blocked the migration routes that Neanderthals used, we may have contributed to their extinction by forcing more inbreeding without directly interfering with them, he says.
