Evolution and humans: why Neanderthals disappeared (Evolution)

by David Turell , Thursday, November 28, 2019, 01:32 (1821 days ago) @ David Turell

Perhaps demographics and bad luck:

https://cosmosmagazine.com/palaeontology/did-bad-luck-kill-the-neanderthals?utm_source=...

"A new study, published in the journal PLoS ONE, suggests that simple fluctuations in the make-up of the population – and a dose of bad luck – were probably enough to push Neanderthals over the edge.

"'What we used to know or think we knew was that we were superior,” says Krist Vaesen from Eindhoven University of Technology in the Netherlands.

"But evidence is stacking up showing that Neanderthals were every bit as sophisticated as our own forebears.

"Another theory suggests that although our ancestors weren’t superior, they were more numerous, arriving in a constant trickle from Africa.

"In any case, none of these external explanations are necessary to explain the Neanderthals’ demise, according to Vaesen and his colleagues.

“'One thing we know about the Neanderthal population is that it was very small,” he says. Estimates suggest there were only ever 5000 to 70,000 Neanderthals at any given time, spread across Eurasia in even smaller, isolated bands.

***

"Starting with populations of between 50 and 5000 individuals, Vaesen and colleagues ran computer simulations, adding in these effects to see how the hypothetical populations fared over a 10,000-year period.

"Inbreeding, though harmful, was not enough on its own to result in extinction, except in the smallest population.

"When low population density was factored in, leading to 25% or fewer females giving birth each year, populations starting with up to 1000 individuals were destined to fail.
Adding in changes to population make-up – factors that are down to pure chance – saw populations of all sizes go the way of the Dodo.

“'What it strongly suggests is that we need to take into account demography,” says Vaesen, rather than looking just at external factors. “And many models don't do that.”
Humans, Vaesen concedes, could have made things worse.

"It’s possible, he says, that “the mere presence of Homo sapiens in Europe and the Near East just made it much more difficult for Neanderthals to migrate among subpopulations,” thwarting any attempts by subpopulations to occasionally meet and mate.

"And luck – of the more favourable kind – could also have played a role in our own species prehistory, says Vaesen."

Comment: Neanderthals are getting smarter and smarter. Note David Raup book thinks extinction is primarily bad luck.