Human Expansion Blamed for Cave Bear Decline
Posted on August 24, 2010
The cave bear (Ursus spelaeus) started to become extinct in Europe about 24,000 years ago. The large cave dwelling bears weighed (PDF file) about 400 to 500 kilograms.
An international team of scientists have analysed mitochondrial DNA sequences from 17 cave bear fossil samples, and compared these with the modern brown bear. The scientists say the results show that the decline of the cave bear started 50,000 years ago, and was caused more by human expansion than by climate change. Humans and cave bears both used caves as habitats and it is highly unlikely they could have lived together peacefully.
Aurora Grandal-D'Anglade, co-author of the study and a researcher at the University Institute of Geology of the University of Coruna, says, "The decline in the genetic diversity of the cave bear (Ursus spelaeus) began around 50,000 years ago, much earlier than previously suggested, at a time when no major climate change was taking place, but which does coincide with the start of human expansion."
According to the research study, published in the journal Molecular Biology and Evolution, radiocarbon dating of the fossil remains shows that the cave bear ceased to be abundant in Central Europe around 35,000 years ago. The scientists attribute this decline to "increasing human expansion and the resulting competition between humans and bears for land and shelter."
The scientists think the present day brown bear did not suffer the same fate and has survived until today because they did not depend as heavily on caves for habitat. The researchers think this is why brown bears did not follow the same extinction pattern as the cave bears.
"Brown bears rely on less specific shelters for hibernation. In fact, their fossil remains are not very numerous in cave deposits", the Galician researcher says.