Cave Bears and Humans: A 400,000-Year Relationship

At the bottom of a 13-metre shaft in the Sima de los Huesos, in Spain's Sierra de Atapuerca, excavators have recovered the bones of at least 28 early Neanderthals, about 430,000 years old (see Sima de los Huesos vs Denisova Cave). The same pit holds thousands of bones from bears of the cave bear lineage, Ursus deningeri. Bears and people ended up in the same dark hole.

That pit is an early chapter in the long relationship between cave bears and humans. For hundreds of thousands of years, both needed the same thing: a dry, sheltered cave.

Meet the cave bear

The cave bear, Ursus spelaeus, evolved from Ursus deningeri and lived across Europe from Spain to the Urals. It was larger than most living brown bears. Big males may have weighed several hundred kilograms, with a domed forehead and massive limbs. Males were much bigger than females.

The name comes from where its bones are found. Some caves contain the remains of thousands of individuals, built up over millennia as bears died during winter hibernation. Drachenhöhle near Mixnitz in Austria held so many bones that its phosphate-rich cave earth was mined as fertiliser in the early 20th century.

A mostly vegetarian giant

Despite its size and large canines, the cave bear was mainly a plant-eater. Its molars are broad and flat for grinding, and the premolars that brown bears use for slicing meat were often reduced or missing.

Bone chemistry supports this. Nitrogen isotope values for most cave bear populations are low, like those of herbivores. There are exceptions. In 2008, Michael Richards and colleagues found that cave bears from Peştera cu Oase in Romania had much higher nitrogen values, pointing to an omnivorous diet that included meat. Diets probably varied by region and period, as they do in brown bears today.

Cave bears and humans: sharing the cave

For Neanderthals and later modern humans, caves were valuable shelter. So they were for bears, which needed protected chambers to hibernate through long winters.

Usually the two did not live in a cave at the same time. Humans tended to use the entrance zones, often in warmer seasons. Bears went deeper and used caves in winter. Over centuries, though, the same caves record both. Claw marks scrape the walls, hollows mark where bears slept, and human hearths and tools lie near the entrances.

Waking a hibernating bear, or entering a cave in spring when hungry bears emerged, was dangerous. It is likely that some humans died this way, though direct evidence is rare.

Did humans hunt cave bears?

Sometimes. The clearest evidence comes from the Swabian Jura in southwest Germany. At Hohle Fels, Susanne Münzel and Nicholas Conard found cave bear bones with cut marks from skinning and butchery, and a vertebra with a flint fragment embedded in it, in Upper Palaeolithic layers. That suggests modern humans killed bears, possibly while they were hibernating.

For Neanderthals, evidence is patchier. Cut marks on cave bear bones at several sites show that they butchered bears, but it is often unclear whether they hunted them or scavenged animals that died in winter. Our article on what Neanderthals hunted covers their wider diet.

The "cave bear cult" myth

Between 1917 and 1923, the Swiss archaeologist Emil Bächler excavated Drachenloch, a cave high in the Swiss Alps. He reported bear skulls arranged in a stone "chest" and in rows along the walls. He interpreted this as an altar, and a Neanderthal cave bear cult entered popular books, museum displays and novels.

Later researchers took the evidence apart. Bächler's records were poor and no photographs of the key features exist. Studies of other bear caves showed that water, sediment movement and the bears themselves can produce clusters of skulls and "arrangements" of stones. By the late 20th century, most specialists had concluded that there is no good evidence for a cult, and that view still holds.

It is a classic case of a vivid story outrunning the evidence. A similar debate surrounds claims of ritual at other sites, as in the arguments over Homo naledi burials.

Bears in Ice Age art

What is not in doubt is that bears mattered to Ice Age people.

• Chauvet Cave, France (~36,000 years ago). The cave holds paintings of cave bears, large numbers of bear bones, claw marks and hibernation hollows. In one chamber, a bear skull sits on a fallen block of rock in the middle of the floor. Whether a person placed it there is unknown.
• Montespan, France. In 1923, the caver Norbert Casteret found a headless clay model of a bear on the floor of a cave passage. A real bear skull lay between its front paws, leading to suggestions that a bear skin with the head attached was once draped over the model.
• Divje Babe, Slovenia (~50,000–60,000 years ago). A juvenile cave bear thigh bone with holes has been claimed as a Neanderthal flute. Others argue the holes are carnivore bites. See the oldest musical instruments for the debate.

Why cave bears went extinct

Cave bears disappeared around 24,000 radiocarbon years ago, roughly 28,000 calendar years ago, according to a dating study by Martina Pacher and Anthony Stuart in 2009. That was before the coldest phase of the last Ice Age.

Ancient DNA shows a long decline. In 2010, Mathias Stiller and colleagues found that cave bear genetic diversity fell for about 25,000 years before the species vanished. Three causes probably combined:

• Climate. Cooling shrank the plant foods a specialist herbivore relied on.
• Low mobility. Cave bears seem to have returned to the same caves, which made it harder to shift range.
• Humans. Growing populations of modern humans competed for caves and hunted bears at some sites.

Scientists still argue about how much weight each factor deserves.

Cave bear DNA in living bears

Like Neanderthals, cave bears did not vanish completely. In 2018, Axel Barlow and colleagues found that living brown bears carry between about 0.9% and 2.4% cave bear DNA, the result of interbreeding during the Ice Age. The parallel with humans is close: most people outside Africa carry around 2% Neanderthal DNA.

Why it matters

The cave bear shows how closely humans and large animals lived together in Ice Age Europe, and how carefully the evidence must be read. Real hunting and art sit beside a myth that lasted for decades. For more animals that shared the world with early humans, see Ice Age animals early humans encountered, or explore the interactive family tree.