Global warming is threatening the existence of a lot of species on the planet right now. But climate change of a different sort -- cooling -- may have contributed to the demise of the Neanderthals, a species that's an extinct relative of modern humans, around 40,000 years ago.
In a study recently published in Journal of Human Evolution, Jamie Hodgkins, a zooarchaeologist and assistant professor in the Zoology department at the University of Colorado-Denver, studied bones from caves once inhabited by Neanderthals in southwest France. In particular, Hodgkins looked at how the carcasses of deer and other animals were butchered and used for food.
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Hodgkins found that during colder, glacial periods, Neanderthals processed the bones more heavily, splitting them for marrow - a sign of food scarcity in the colder climate.
"Our research uncovers a pattern showing that cold, harsh environments were stressful for Neanderthals," Hodgkins said in a press release. "As the climate got colder, Neanderthals had to put more into extracting nutrients from bones. This is especially apparent in evidence that reveals Neanderthals attempted to break open even low marrow yield bones, like the small bones of the feet."
Hodgkins' findings add more evidence to support the hypothesis that climate change may have been a significant factor in the demise of the Neanderthals.
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"Our results illustrate that climate change has real effects," said Hodgkins. "Studying Neanderthal behavior is an opportunity to understand how a rapidly changing climate affected our closest human relatives in the past. If Neanderthal populations were already on the edge of survival at the end of the Ice Age, the increased competition that occurred when modern humans appeared on the scene may have pushed them over the edge."
According to this hypothesis, as the temperature dropped, both Neanderthals and modern humans were compelled to move around more in search of food, and encountered each other more often. That would have led to inter-species breeding over a 5,000-year period that eventually resulted in the extinction of the Neanderthals as a separate species.
Most humans outside of Africa today have some Neanderthal DNA, and scientists say the extinct species had a significant influence on our biology.
Scientists have discovered that modern humans also interbred with another, lesser-known group of hominids, the Denisovans. A 2016 study found that people of South Asian descent have more Denisovan DNA than other ethnic groups.