The cave bear (Ursus spelaeus) was a type of ancient bear that lived in Europe and Asia during the Ice Age. It disappeared about 24,000 years ago, during the coldest part of the Ice Age.
The name "cave bear" comes from the fact that most of their bones were found in caves. Scientists believe cave bears spent more time in caves than brown bears, often using them to hibernate during winter. Unlike brown bears, cave bears likely ate mostly plants.
Cave bears showed many differences in size, body shape, and genes. Some scientists think Late Ice Age cave bears were actually several different species, possibly as many as six.
Taxonomy
Cave bear skeletons were first described in 1774 by Johann Friedrich Esper in his book Newly Discovered Zoolites of Unknown Four-Footed Animals. At the time, scientists thought the bones might belong to apes, dogs, cats, or even mythical creatures like dragons or unicorns. Esper, however, believed the bones belonged to polar bears. Twenty years later, Johann Christian Rosenmüller, an anatomist at Leipzig University, gave the species its scientific name. Many researchers at the time paid little attention to the bones because there were so many of them. During World War I, when phosphate dung became scarce, soil from caves containing cave bear bones was used as a source of phosphates. In Austria’s Styria region, only the skulls and leg bones from these caves were kept for study.
Many caves in Central Europe contain cave bear skeletons, such as the Heinrichshöhle in Hemer and the Dechenhöhle in Iserlohn, Germany. In 1966, a complete skeleton, five skulls, and 18 other bones were found in Kletno Bear Cave in Poland. In 1983, 140 cave bear skeletons were discovered in a cave called Bears' Cave in Romania.
Remains from the Late Pleistocene labeled as "cave bears" show many differences in size and shape. These remains have often been classified into separate species, such as Ursus rossicus (Eastern Europe, Central Asia, and Siberia), Ursus ingressus (Central Europe to the Urals), Ursus kanivetz (Urals), Ursus kudarensis (the Caucasus), Ursus eremus (Central Europe, possibly a subspecies of U. spelaeus), and Ursus spelaeus (Western, Central, and Southeast Europe). These groups show significant genetic differences, with estimates suggesting they diverged hundreds of thousands to a million years ago. However, whether these groups are separate species or variations of U. spelaeus remains debated.
Both cave bears and brown bears are believed to have descended from the Early Pleistocene species Ursus etruscus. Scientists estimate that the ancestors of cave bears and brown bears split around 1.2 to 1.5 million years ago. The earliest remains of the cave bear lineage are from Ursus deningeri, which appeared in the fossil record at the end of the Early Pleistocene, about 1.2 to 0.8 million years ago. U. deningeri fossils have been found in Europe and China. The transition from U. deningeri to U. spelaeus is often linked to the Last Interglacial period (130,000 to 115,000 years ago), though this boundary is not clearly defined. Some scientists propose intermediate species, such as Ursus spelaeus deningeroides, while others argue that U. deningeri and U. spelaeus are variations of the same species over time.
Cave bears found in different regions vary in age, which helps scientists study evolutionary changes. Over time, the three front premolars of cave bears gradually disappeared, possibly due to their mostly plant-based diet. In a quarter of the skulls found in the Conturines, the third premolar is still present, while other specimens lack it. The last remaining premolar fused with the molars, increasing the size of the molars and giving them more ridges for chewing. This process, called molarization, improved the cave bear’s ability to process tough vegetation. This adaptation allowed cave bears to gain more energy for hibernation while eating less than their ancestors.
In 2005, scientists extracted and sequenced the nuclear DNA of a cave bear that lived between 42,000 and 44,000 years ago. They used DNA from one of the animal’s teeth and directly sequenced it without first copying it using traditional methods. This process allowed them to recover 21 genes from remains that had not yielded much DNA using older techniques. This study supported earlier findings from mitochondrial DNA analysis of cave bear remains dating from 20,000 to 130,000 years ago. Both studies showed that cave bears were more closely related to brown bears and polar bears than to American black bears. However, cave bears split from the brown bear lineage before the brown bear’s eastern and western groups diversified and before the split between brown bears and polar bears. A recent study also found evidence that cave bears and brown bears may have interbred at some point.
Description
The cave bear had a broad, rounded head with a steep forehead. Its strong body had long legs, thick lower legs, and feet that turned inward, making its skeleton similar to that of the brown bear. Cave bears were as large as or larger than today's biggest bears, growing up to 2 meters (6.6 feet) long. Male cave bears usually weighed between 350 to 600 kilograms (770 to 1,320 pounds), while females weighed between 225 to 250 kilograms (495 to 550 pounds). Most cave bear skeletons in museums are from males because people once mistakenly believed female skeletons were simply smaller versions. Cave bears grew larger during ice ages and smaller during warmer periods, likely to manage body heat more effectively.
The shape of the cave bear’s lower jaw changed based on climate. Those living in colder, drier, and more seasonal areas had narrower jawbones and a shorter part of the jaw connecting to the skull compared to those in warmer, wetter areas. Cave bears from the last Ice Age lacked the typical two or three premolars found in other bears. Instead, their last molar was very long and had extra bumps. The upper arm bone of the cave bear was similar in size to that of the polar bear, as were the thigh bones of females. However, the thigh bones of male cave bears were more similar in size to those of Kodiak bears.
Behaviour
Cave bear teeth were very large and showed more wear than most modern bear species, suggesting they ate tough materials. However, studies of tiny wear marks on their teeth (dental microwear analysis) suggest that tubers and gritty foods, which cause specific tooth wear in modern brown bears, were not a major part of their diet. Other studies using dental microwear texture analysis (DMTA) found that cave bears ate foods with textures similar to those of modern bear species, except for polar bears. At least one group of cave bears from Goyet Cave in Belgium had DMTA values showing they ate only soft foods. Seed fruits are known to have been eaten by cave bears. At a high-altitude site called Ramesch-Knochenhöhle, wear marks on cave bear teeth suggest some individuals ate large amounts of sand while eating alpine plants. This site also showed two different wear patterns among the same subspecies, which might reflect differences in eating habits between male and female cave bears. Cave bears mainly ate C3 plants and foraged in forests, though their diet had a wider range than Deninger's bears or brown bears.
The shape of cave bear jaws and teeth, including the loss of certain teeth, suggests their diet included more plant material than Eurasian brown bears. Some evidence even suggests they may have been entirely vegetarian, based on the shape of their teeth. Studies of stable isotopes in cave bear bones also support a mostly plant-based diet, as their bones had low levels of nitrogen-15 and carbon-13, which are higher in carnivores. In Mediterranean cave bears, such as those in Toll Cave in Spain, very low nitrogen levels might be due to eating plants that fix nitrogen in the soil.
Some evidence suggests cave bears occasionally ate animal protein. For example, toothmarks on cave bear bones in areas where they were the only known predators suggest they may have scavenged dead animals, possibly those that died during hibernation. Wear marks on their teeth also suggest they ate more bone than modern brown bears. In the northeastern Iberian Peninsula, wear patterns on cave bear molars indicate they may have eaten more meat before hibernation. In Belgium, wear marks on teeth show they ate bone, insects, and mammal meat before hibernation. Studies comparing brown bears and cave bears in northern Spain found cave bears ate more bone than brown bears. In Romania’s Peștera cu Oase, cave bear bones had higher nitrogen-15 levels, suggesting they ate some meat, though their levels were similar to those of herbivorous mammoths. One study found cave bears’ diets were as varied as modern brown bears.
Most scientists believe cave bears were mostly herbivorous, more so than any modern bear species. However, new evidence suggests their diets varied by region and included both plants and animals. Recent studies of their skulls and teeth place cave bears among modern omnivorous bears.
Many cave bears died during hibernation, often due to failing to survive the summer season because of inexperience, illness, or old age. Some bones show signs of health problems, including fused spinal bones, bone tumors, cavities, tooth loss, dead tissue, infections, and kidney stones. Evidence also shows some cave bears had tuberculosis. Male cave bears had broken bones in their reproductive organs, likely from fighting during mating season. Scientists believe cave bears rarely lived past 20 years old. Adult cave bears likely had no natural predators except wolves and cave hyenas, which might have attacked sick or weak individuals. Cave hyenas may have broken apart some cave bear skeletons, as their large bodies were a valuable food source during winter. Fully intact adult cave lion bones found deep in cave bear dens suggest lions sometimes entered dens to hunt hibernating cave bears, with some lions dying in the attempt.
Range and habitat
The cave bear lived in many parts of Europe, including Spain, the British Isles, Belgium, Italy, parts of Germany, Poland, the Czech Republic, the Balkans, Romania, Georgia, and parts of Russia, such as the Caucasus, as well as northern Iran. Evidence of cave bears has not been found in the northern British Isles, Scandinavia, or the Baltic countries because these areas were covered by large glaciers during the time the cave bear lived. The most cave bear remains have been discovered in Austria, Switzerland, northern Italy, northern Spain, southern France, and Romania. These areas are near mountain ranges like the Pyrenees, Alps, and Carpathians. Scientists have noted that the large number of bones found in southern, central, and eastern Europe suggests Europe may have once had groups of cave bears. However, other scientists explain that the bones in some caves were collected over 100,000 years or more, which would mean only two cave bears dying in a cave each year could explain the large number of bones. Cave bears lived in low mountain areas, especially places with many limestone caves. They avoided open plains and preferred forests or areas near forests.
Relationship with humans
Cave bear and brown bear remains that were modified by Neanderthals to be used as tools have been found in many areas across Europe. This shows that Paleolithic humans used bear carcasses for practical purposes. Evidence suggests that Neanderthals may have hunted these bears when the chance arose or competed with them for resources.
Between 1917 and 1923, Emil Bächler excavated the Drachenloch cave in Switzerland. The dig uncovered more than 30,000 cave bear skeletons. It also found a stone chest, made of limestone slabs near a cave wall, containing several bear skulls. One skull had a femur bone from another bear inside it. Experts thought this might show that early humans performed religious rituals honoring cave bears, showing respect or spiritual beliefs about the animals. However, others suggested the skulls were trophies from hunting or part of a hunting ritual, not religious practices. In a book titled Archaeology, Religion, Ritual (2004), archaeologist Timothy Insoll questioned whether the Drachenloch findings were linked to human religious activity. He said the evidence for religious practices involving cave bears during this time is "far from convincing." Insoll also said comparing these ancient practices to later known bear-related rituals is not valid.
A similar discovery was made in Regourdou, southern France. A rectangular pit held the remains of at least twenty bears, covered by a large stone slab. Nearby, in another pit, the remains of a Neanderthal were found with objects like a bear humerus, a scraper, a core, and flakes, which were considered grave offerings.
In Basura Cave, Savona, Italy, an unusual find was made in a deep chamber. A stalagmite shaped like an animal was surrounded by clay pellets, leading some to think it was connected to cave bear worship. Neanderthals may have used the area for a ceremony, as bear bones scattered on the floor suggest a ritual purpose.
Extinction
In 2019, a review of fossils suggested that the cave bear likely became extinct about 24,000 years ago. Scientists believe that many different factors, not just one, contributed to the extinction.
Compared to other large animals that also went extinct during the Last Glacial Maximum, the cave bear had a diet focused on high-quality plants and lived in a limited area. This may explain why it disappeared earlier than other species. However, some experts disagree, noting that the cave bear had survived earlier climate changes. Research on mitochondrial DNA showed that the cave bear’s genetic diversity began to decrease long before extinction, suggesting that habitat loss from climate change was not the main cause. Additionally, high δ N levels found in cave bear bones from Romania indicated the species may have eaten a wider variety of foods than previously thought.
Some evidence suggests that cave bears hibernated only in caves, unlike brown bears, which used other areas like thickets. This behavior may have caused high winter deaths if suitable caves were unavailable. As human populations grew, cave bears faced fewer caves to use for hibernation, as humans began to live in caves themselves. This idea is still being studied, and research published in Molecular Biology and Evolution in 2010 showed that cave bears were no longer common in Central Europe around 35,000 years ago.
Human hunting has also been linked to the extinction of the cave bear. A 2019 study of 81 bone samples and 64 published mitochondrial DNA sequences from caves in multiple countries found that the cave bear population declined sharply around 40,000 years ago, when anatomically modern humans arrived. Researchers concluded that human hunting or competition, not climate change, was likely the main cause of the decline. Studies of cave bear remains in Spain showed that each cave contained unique genetic lineages, suggesting cave bears returned to the same caves for birthing and hibernation. This behavior may have made it harder for cave bears to find new habitats when competing with humans.
Some scientists argue that early human populations were too small to hunt cave bears to extinction. However, humans and cave bears may have competed for cave space. The Chauvet Cave, for example, has about 300 "bear hollows" used for hibernation. Unlike brown bears, cave bears are rarely shown in cave paintings, leading some to think humans may have avoided hunting them or their habitats did not overlap. Paleontologist Björn Kurtén suggested that cave bear populations were already fragmented and stressed before glaciers formed, and some groups in southern regions may have survived longer.