Swamp Stomp

Volume 18 Issue 37

Twenty-four thousand years ago, give or take, the species known as the cave bear, was eliminated from the Earth. Scientists have not been able to pinpoint the exact cause of the extinction of the cave bear, but they have chalked it up to possible over-hunting and competition with humans for resources. Cave bears, however, may not be as extinct as we once thought they were.

Brown bears can be found throughout the forests and tundra of North America and Eurasia. There are more than 200,000 brown bears worldwide, and researchers have found that 0.9-2.4% of living brown bears’ DNA can be traced back to cave bears. This may not appear to be such an overwhelming discovery, but it is actually only the second time a present-day species’ DNA has been found to be traceable back to a species that was alive during the ice age. Humans are the only other species with this characteristic with 1.5-4% of our DNA being traceable back to Neanderthals. Just like humans, brown bears contain this ancient DNA via interbreeding between the old and the new species.

Axel Barlow, a postdoctoral researcher at the University of Potsdam and one of the study’s lead authors, studied the genomes of polar bears, brown bears, and cave bears and compared them to each other. They found the genomes of brown bears and cave bears to be much more similar than the genomes of brown bears and polar bears. This confirmed that interbreeding had to occur to account for these similarities. Rasmus Nielsen, a geneticist at the University of California, Berkeley, notes, “The old-fashioned idea of a species [is that] it’s reproductively isolated from other species. This paper is a part of a series of papers that have been saying that worldview really is wrong.”

What is the significance? By discovering that Neanderthal DNA exists inside humans of today, scientists have been able to uncover aspects of humans from immunity to hair structure. So, this new knowledge could teach us something about unknown aspects of brown bears, who serve as important predators, as well as seed dispersers, in their ecosystems. However, Barlow adds, “It forces us to think on a philosophical level what we mean by species extinction.” In other words, when we say a species is extinct, we imagine it erased completely from the present, but we are finding out this is untrue. The cave bear may no longer physically roam the planet, but it lives on in the DNA of brown bears. Perhaps there will be other species found not to be as extinct as we had once thought?

Sources:

“Brown Bear.” WWF. WWF. N.d. Web. September 2, 2018.

Greshko, Michael. “Extinct Cave Bear DNA Found in Living Bears.” National Geographic. National Geographic. August 27, 2018. Web. September 2, 2018.