The cave bear, Ursus spelaeus, was a heavy, mostly plant-eating bear that lived in Europe and as far east as northern Iran, from about 250 000 to 24 000 years ago. Large males matched or outweighed the biggest bears alive today. It spent its winters underground, and so many died there that some caves hold thousands of its bones, making it one of the best-known animals of the Ice Age. Fragments of its DNA still survive in living brown bears.
Winters underground
Cave bears kept to low mountain country rich in limestone caves, with forest or forest edge, and they avoided open plains. In the cold months they went underground. Chauvet Cave in France has about 300 resting hollows, 80 cm to almost 1.5 m across and usually 30 to 50 cm deep, worn by bears returning to the same spots. The French culture ministry’s account describes a state of semi-lethargy, not true hibernation, while other studies use the word hibernation.
Death in the den was common, mainly among animals that had failed during the summer through inexperience, sickness or age. Their bones show spinal fusion, tumours, rickets and signs of tuberculosis. The numbers once suggested herds, but the piles built up over 100 000 years or more, so about two deaths a year in a cave would account for them.
Early finds were badly misread. Esper, who described skeletons in 1774, thought they were polar bears, while others of his time considered apes, dragons and unicorns. During the First World War, earth from these caves was dug out for its phosphate.
A head built for chewing
Below the neck the skeleton resembles a brown bear’s, with long thighs, massive shins and in-turned feet. The head is the difference: a very broad, domed skull with a steep forehead. Through time the front premolars shrank and disappeared, the last premolar grew more like a molar, and the last molar lengthened and gained extra cusps. Those changes improved its ability to chew tough vegetation.
Males far outweighed females, at about 350 to 600 kg against 225 to 250 kg, and the species grew larger in glacial periods and smaller in warmer ones.
Plant-eater, with exceptions
Low nitrogen-15 and carbon-13 in its bones point to a largely plant diet, foraged mainly in forest. The picture has become less tidy. Tooth wear shows that feeding habits differed by region: bears high in the Totes Gebirge swallowed sand along with alpine plants, while bears in Belgium ate bone, insects and meat before winter. One isotope study found omnivory on a par with modern brown bears.
In 2025 Meleg and colleagues combined isotopes and ancient DNA for bears from the Romanian Carpathians. Individual diets varied widely, and the variation did not follow population, sex, period, climate or place. They concluded that diet was shaped by each bear’s foraging experience and was not inherited.
Two stories that did not hold
Excavations at Drachenloch in Switzerland between 1917 and 1923 uncovered a low wall of limestone slabs enclosing bear skulls, read as proof of prehistoric bear worship. In 2004 the archaeologist Insoll questioned whether people had made the arrangement at all, and called the evidence for such rites “far from convincing”.
More recently, a well-preserved carcass from the Lyakhovsky Islands, recovered in 2020, was announced as a cave bear about 30 000 years old. A new necropsy reported in 2023 identified a young brown bear about 3 500 years old.
A long decline
A 2010 genetic study led by Stiller found that cave bear numbers began falling about 25 000 years before extinction, while brown bears held steady. The authors concluded that neither climate nor hunting alone could explain this, and suggested a mix of causes that included competition with people for caves. A 2019 study led by Gretzinger, with 59 new mitochondrial genomes, found a sharper fall from about 40 000 years ago as modern humans spread through Europe, and saw support for a potentially significant human role. Others reply that people were too few to pose such a threat.
Most radiocarbon dates end around 28 000 to 26 000 years ago, and a few relict populations lasted longer. The youngest DNA sequence, from Trene in Italy, is 23 907 to 23 461 years old.
The line did not vanish entirely. Cave bears interbred with brown bears, and a 2018 study led by Barlow found that they contributed 0.9 to 2.4 per cent of the genomes of all the living brown bears it examined.
