Neandertal Population Size: The Cause for Extinction?

The Max Planck institute has released findings that suggest that Neandertals became extinct because they were below effective population size. Live Science reports that:

Neanderthals are of course extinct. But there never were very many of them, new research concludes.

In fact, new genetic evidence from the remains of six Neanderthals (Homo neanderthalensis) suggests the population hovered at an average of 1,500 females of reproductive age in Europe between 38,000 and 70,000 years ago, with the maximum estimate of 3,500 such female Neanderthals.

"It seems they never really took off in Eurasia in the way modern humans did later," said study researcher Adrian Briggs of the Max-Planck Institute for Evolutionary Anthropology in Germany.

The research, which will be published in the July 17 issue of the journal Science, suggests the small population size of our ancestral cousins may have been a factor in their demise.

It wasn't for lack of intelligence. As the story notes, Neandertals were far from stupid:

Rather than the dumb cavemen characters starring in Geico car insurance ads, accumulating archaeological and genetic evidence shows Neanderthals were pretty sophisticated. They apparently hunted with blades and spear tips rivaling those of modern humans, ate marine mammals like seals and dolphins and sported brains that grew like ours. Their bodies likely looked similar to ours, and some Neanderthals showed off red locks on their heads.

I am still of the mind that Neandertals did interbreed with the arriving moderns, based on evidence at Arcy Sur-Cure where you have Aurignacian and Chatelperronian tool industries interdigitated, suggesting a somewhat fluid landscape for these hominids. The evidence at Lagar Velho, in Portugal, also suggests interbreeding. But if that didn't happen all over, or if there were conflicts regarding land or food resources, it is easy to see that there may have been a time of admixing and replacement, subsequent to which the Neandertal genome disappeared in the wake of selective pressures for that of modern humans.


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