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How Neanderthals Helped the Human Species Adapt to Cold Climates

As the northern hemisphere wiggles out from Winter’s chilling grasp, most humans dwelling there flock outdoors to welcome the emerging warmth.

A neanderthal, however, might already think it’s getting a tad balmy…

While we can’t know for sure what one of Homo sapiens‘ closest relatives would think of the rising temperatures, anthropologists are fairly certain that Neanderthals were quite acclimated to colder climates. Remarkably well, in fact.

“It is well-accepted that Neanderthals appear to be the most cold-adapted of known fossil hominin groups,” a team of anthropologists recently wrote in the journal Evolutionary Anthropology.

That team, comprised of Dr. Cara Ocobock, a biological anthropologist at Notre Dame, Dr. Sarah Lacy, a paleoanthropologist at California State University Dominguez Hills, and Alexandra Niclou, a PhD candidate in biological anthropologist at Notre Dame, dove into the published research to amalgamate the current state of knowledge concerning Neanderthal cold adaptations.

“Neanderthals display a potentially unique suite of characteristics that enabled them to survive and thrive in cold, glacial climates,” they found.

Consider that while we Homo sapiens spent much of our time on Earth in Africa around the equator, Neanderthals dwelled further north, predominantly in dry, and even polar, climates, as far as northern France, through mountainous Uzbekistan, and even to southern Siberia. In these often harsh environments, they had hundreds of thousands of years to adapt morphologically, physiologically, and behaviorally.

diagram, map: Ocobock et al. / Evolutionary Anthropology © Provided by Real Clear Science Ocobock et al. / Evolutionary Anthropology

Ocobock et al. / Evolutionary Anthropology

Neanderthals’ morphological adaptations to the cold are perhaps the most apparent, as scientists can study their bones and make conclusions about their bodies with a fair degree of certainty. For example, Neanderthals had broad trunks and shortened limbs compared to other hominins, which granted a relatively high body volume with a lower surface area.

“This would have maximized potential metabolic heat production while minimizing heat loss to the environment,” the authors wrote.

Neanderthals also had tall, broad, and generally large noses.

“This particular nasal shape is considered adaptive, as a tall, narrow nasal passageway increases mucosal surface area, providing greater ability to warm and moisten cold-dry air typical of cold climates,” Ocobock and her colleagues explained.

Lastly, in terms of morphology, Neanderthals had sizable skeletons, hinting at prodigious muscle mass. Muscle produces more heat than fatty tissues, but is also more energetically expensive.

That’s where diet factored in. Given Neanderthals’ muscled frames, they likely had much higher metabolisms than other hominins. This demanded calories. A great source of calories is large-bodied game. Deer, ibex, wild boar, aurochs, and occasionally mammoth and woolly rhinoceros, were some of their frequent fare. All of this protein consumption likely boosted their metabolisms even more, thus making their bodies produce more heat.

Hunting, of course, was a physically demanding activity, involving sprinting, throwing, and carrying heavy loads. All of this exercise, coupled with cooler temperatures, would likely have prompted Neanderthals to develop significant stores of brown fat, which, compared to normal white fat, contains a lot more mitochondria. These cellular ‘power plants’ are adept at producing heat for warmth.

While Neanderthals’ morphological and physiological adaptations can be reasoned based upon fossil and archaeological evidence, their behavioral adaptations are more of a mystery. We know that Neanderthals made clothing, but scarce evidence of it has survived over the millennia. We also know that they often used caves for shelters and built fires for warmth and cooking. Harder to discern are the cultural and social systems they adopted to thrive in colder climates.

“Most of these behaviors will be archaeologically invisible to us, though assuredly Neanderthals had systems of food sharing and other cultural buffering mechanisms to cope with the cold,” the authors wrote.

Ocobock, Lacy, and Niclou caution that a lot of the findings gleaned from the literature are speculative, but as more discoveries are made in the coming years, our knowledge of Neanderthals will grow.

“There is a great deal yet to be uncovered about the nature and manifestation of Neanderthal adaptation and how the synergy of biology and culture helped buffer them against extreme and variable environments,” they say.

Source: Ocobock C, Lacy S, Niclou A. “Between a rock and a cold place: Neanderthal biocultural cold adaptations.” Evol Anthropol. 2021 Apr 2. doi: 10.1002/evan.21894. Epub ahead of print. PMID: 33797824.