cave bear
cave bear, either of two extinct bear species, Ursus spelaeus and U. deningeri, notable for their habit of inhabiting caves, where their remains are frequently preserved. They are best known from late Pleistocene cave deposits (the Pleistocene Epoch lasted from about 2.6 million to 11,700 years ago), although they can be traced back to Late Pliocene times (the Pliocene Epoch spanned from about 5.3 million to about 2.6 million years ago). In European cave deposits the remains of more than 100,000 cave bears have been found.
(Read E.O. Wilson’s Britannica essay on mass extinction.)
Cave bear remains have been found in England, Belgium, Germany, Russia, Spain, Italy, and Greece, and the animal may have reached North Africa. Several local varieties, or races, have been described; dwarf races are known from some regions. Stone Age peoples sometimes hunted the cave bear, but evidence of that hunting is very sporadic; it is highly unlikely that hunting by human beings caused its extinction. It appears likely that most cave bears died in the severe glacial winters during dormancy; the remains include a large proportion of very young or very old bears and many specimens showing unmistakable signs of illness or disease. One study suggests that the extinction of U. spelaeus may have been related to evolutionary changes in the skull, which resulted in enlarged sinuses that helped the bear survive dormancy at the expense of a thinner skull, which reduced the animal’s biting force and limited its diet to softer, low-value foods. Extinction of the cave bear seems to have been a gradual process that was complete between 28,000 and 27,000 years ago.
The cave bear’s weight ranged from 400 to 1,000 kg (about 880 to 2,200 pounds), the largest cave bears being comparable in size to the Kodiak bears (U. arctos middendorffi) of Alaska and the polar bears (U. maritimus) of the Arctic. The head was very large and the jaws bore distinctive teeth, which suggests that the animal was largely vegetarian.
In 2013 a mitochondrial DNA sequence of a cave bear was reconstructed by a group of scientists from a bone fragment discovered at Atapuerca’s Sima de los Huesos (“Pit of the Bones”) cave in Spain. The fragment was dated to more than 300,000 years ago, which made the genome among the oldest ever reconstructed outside of a permafrost environment.