Climate change puts vegetarian cave bear to sleep for good
A group of Austrian and British researchers estimate the extinction date of the huge cave bear Ursus spelaeus that once inhabited Europe to be 27 800 years ago, coinciding with the Last Glacial Maximum, a key period of climate change. During this time the temperature dropped dramatically, triggering the decline or loss of vegetation consumed by the giant creatures. The research was funded by the EU through the AlpiNet (Culture 2000) project, as well as the Cultural Grant of Lower Austria and the National Environment Research Council UK. Their study was recently published in the journal Boreas.
The vegetation loss resulted in the disappearance of the Ursus spelaeus, the first of the 'mega-mammals' to become extinct, 13 000 years earlier than what researchers once believed. Besides the cave bear, mega-mammals included cave lions, woolly mammoths and giant deer.
Researchers have found many cave bear remains in areas where the bears are likely to have died during winter hibernation. These bears were enormous, researchers say; males could weigh up to 1 000 kg. Today's biggest bears, the Kodiak and Polar, weigh around 800 kg, and the average weight of other bears is 500 kg.
Cave bear bones were used for medicinal purposes in the Middle Ages, according to the research team. During that period, people thought the bones belonged to dragons.
A number of theories have emerged over the years about the extinction of the mega-mammals, but concrete results have been elusive. Many researchers believe that mega-mammals disappeared from the Earth because of humans and their hunting activities.
However, University of Vienna's Dr Martina Pacher and Professor Anthony J Stuart from the National History Museum in the UK remarked that no such evidence has emerged for the cave bears. They added that contrary to ideas about a 'hyberdisease' affecting the lives of these mammals, a disease 'is unlikely to explain the timing of the extinctions or that the body sizes of these animals' were so different.
To support the idea of climate change, Dr Pacher combined new and old radiocarbon dating data from cave bear remains to construct the new chronology for cave bear extinction.
'Our work shows that the cave bear, among the megafauna that became extinct during the Last Glacial period in Europe, was one of the earliest to disappear,' Dr Pacher explained. 'Other, later extinctions happened at different times within the last 15 000 years.'
The researchers also discovered that the cave bears were herbivores. Their assessment was based on data from skull anatomy, bone collagen and teeth. From a geographical perspective, they said the cave bear was confined to Europe, in particular between Spain and the Ural Mountains in Russia.
'Its highly specialised mode of life, especially a diet of high-quality plants, and its restricted distribution left it vulnerable to extinction as the climate cooled and its food source diminished,' Dr Pacher said.