It's a sad fact that permafrost all over the world is melting due to global warming. But, as it melts, the permafrost is disgorging creatures not seen for tens of thousands of years.
That's what two reindeer herders on Russia's Bolshoy Lyakhovsky Island, recently discovered when they stumbled upon the almost perfectly preserved carcass of an Ice Age cave bear (Ursus spelaeus). The permafrost had so preserved the cave bear carcass that its teeth, soft tissues, internal organs, and even its snout were intact.
The find was especially important because until now, "only skulls and bones [of cave bears] were found," according to Lena Grigorieva, a molecular paleontologist at North-Eastern Federal University in Yakutsk, Russia.
At almost the same time, on the mainland of Yakutsk, the carcass of a well-preserved cave bear cub was also found, and scientists hope to extract DNA from both carcasses.
Last year, the head of a 40,000-year-old wolf was found on the banks of a river in Yakutsk with its fur, teeth, brain, and facial tissue still intact. The ancient wolf's head was far larger than those of modern wolves, and currently, scientists are building a digital model of the ancient wolf's brain and the skull's interior.
Who was the cave bear?
The newly discovered cave bear lived between 22,000 and 39,500 years ago, and the species became extinct around 15,000 years ago. Cave bears got their name because their fossilized bones have been found primarily in caves.
Cave bears first roamed Eurasia starting around 300,000 years ago, and their range extended from Spain and Great Britain in the west, to Italy, parts of Germany, Poland, the Balkans, Romania, northern Iran, and parts of Russia.
The largest number of cave bear skeletons have been found in Austria, Switzerland, northern Italy, northern Spain, southern France, and Romania. The cave bears living in Siberia likely shared their environment with woolly mammoths, saber-toothed cats, and giant ground sloths.
Cave bear skeletons were first described in 1774, and at the time, scientists thought the bones belonged to apes, wolves, big cats, or even dragons. Twenty years later, an anatomist at Leipzig University formally identified the species.
In 1966, a complete cave bear skeleton, five complete skulls, and 18 other bones were found inside the Polish cave Jaskinia Niedźwiedzia (Polish for "bear cave"). In 1983, at a cave called Bears' Cave in Romania, 140 cave bear skeletons were discovered.
Cave bears were huge, measuring up to 11.5 feet (3.5 m) high when standing on their hind legs, and weighing about 1,100 lbs. (500 kg). A 2018 study in the journal PLOS One put the cave bear's weight at as much as 3,300 lbs. (1,500 kg), which is far more than the weight of their closest living relative, the brown bear (U. arctos).
Both the cave bear and the brown bear are thought to have descended from a common ancestor that lived between 1.2 million and 1.4 million years ago. Analysis of cave bear teeth shows that they were mostly herbivores, eating only plants, unlike modern bears who are omnivorous, eating both plants and animals.
Human effect on cave bears
Cave bears had few enemies, with only wolf packs, cave hyenas, and cave lions posing a threat. However, once humans arrived on the scene, cave bears became threatened. At the Drachenloch cave in Switzerland, which was excavated beginning in 1917, archaeologists uncovered a stone chest containing the skulls of multiple cave bears. In southern France, a similar find was made along with the remains of a Neanderthal.
A 2019 study in the journal Scientific Reports concluded that it is likely that the arrival of anatomically modern humans coincided with the cave bear's extinction because as human populations increased, they sought out homes in the same caves where the bears hibernated.
A 2016 study of the mitochondrial DNA of cave bears living in a Spanish cave showed that many generations of the same cave bear family had lived in the cave. This led to the conclusion that cave bears could not easily find new caves once they had been driven out of theirs by humans, and had nowhere to go to hibernate.
As humans spread out and occupy even more territory, the same fate that befell the cave bear is likely to happen to more animals. The story of the cave bear should be a cautionary tale for us all.