Herbivorous diet may have killed the cave bear

Many explanations have been proposed for the extinction of the cave bear 24,000 years ago. A group of University of Helsinki researchers set about finding the answers in bear teeth using dental equipment.

Teeth are highly valuable for researchers of evolution and developmental biology. Once they have erupted, teeth do not change, except through wear. Teeth can also provide surprisingly detailed information on diet.

The research group, working at the Institute of Biotechnology, created 3D models of the teeth of Finnish brown bears, American and Asian black bears, sun bears, polar bears and giant pandas, and compared them to equivalent models created based on cave bears.

Herbivores have complex teeth

Together with her colleagues, researcher Jacqueline Moustakas-Verho compared the complexity of the structure of the molars in different bears. This can reveal the animal’s diet. The more complex the teeth, the more plants they ate.

The result was astounding. The molars of the cave bear were the most complex of any of the bears, so the researchers believe it may have been fully herbivorous. Perhaps climate change disrupted the food supply of the herbivorous cave bears, while the omnivorous members of its family survived.

The researchers were even more surprised to discover the vast variation in molar structure between individual bears. Variation in the teeth speaks of a stressful environment. For example, the individual may not have found sufficient or suitable food early in its life, resulting in abnormal development of the teeth.

Why did the environment become stressful for the cave bear, which had lived in Eurasia for hundreds of thousands of years, while the brown bear survived in the same area and continues to thrive even in Finland? The research group is still working to find the answer.

3D scanning museum collections

The study combined palaeontological materials with zoological ones. Some of the samples came from the collections of the Finnish Museum of Natural History Luomus. A central part of the research material consisted of a collection of cave bear skulls and bones, collected by the University of Helsinki’s Professor Alexander von Nordmann in the early 19th century. The collection is stored in its entirety in the Kumpula manor.

Skulls from modern bears were received from the Zoology Unit of Luomus.

More to come

Jacqueline Moustakas-Verho presented her preliminary results last summer at the International Congress of Vertebrate Morphology held in the United States. An article on the topic is planned to be published next autumn.

The study was carried out by Professor Jukka Jernvall’s Helsinki EvoDevo research group focusing on evolutionary developmental biology at the Institute of Biotechnology. The study was made possible by Plandent, Finland’s leading producer of dental equipment.

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