Cavemen may have had to jostle with bears to settle into caves up to 32,000 years ago, as research shows cave bears lived in the same spaces coveted by prehistoric humans.
The new study on cave bears, which has been accepted for publication in the Journal of Archaeological Science, may also shed light on the age of cave art depicting these enormous animals and why the bears eventually went extinct.
A clue to the mysteries is that from 32,000 to 30,000 years ago, both humans and cave bears lived in two French caves, creating a likely man-versus-bear battle.
"Paleolithic humans used to kill large animals during their hunts, so they were able to kill cave bears," lead author Celine Bon told Discovery News.
While genetics show cave bears consumed a mostly vegetarian diet, "they might have been violent if they were disturbed during hibernation or if they felt frightened," added Bon, a researcher in the Institute of Biology and Technology at Saclay, France.
"In such a case, they may have been very dangerous because of their huge size and their impressive claws and canines (teeth)."
For the study, Bon and her colleagues performed radiocarbon dating, mitochondrial DNA analysis and isotope investigations of cave bear remains from Chauvet-Pont d'Arc and Deux-Ouvertures caves located along the Ardeche River in France. Both caves feature art on the walls, some of which shows cave bears.
The tests revealed that cave bears inhabited the Ardeche region from around 37,000 to 27,400 years ago, with the oldest samples from Chauvet dating to 29,000 years ago. For a while, the bears had few rivals for the caves
That changed when humans first began to use the natural shelters 32,000 to 30,000 years ago. The DNA analysis determined the cave bear population was small and isolated, and that the bears probably died out not long after humans came onto the scene.
"The cave bear population began to decline at the same time that modern humans arrived in Europe," Bon said. "Yet it is unclear if humans are responsible for the cave bear extinction because of competition over space or food resources, or if the extinction of cave bears is due to climatic and/or environmental changes.
"Our data favor both explanations because they show a small cave bear population size in caves occupied by humans."
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She thinks it's doubtful the bears and humans ever lived together simultaneously in the caves. Despite the probable competition, there appears to have been a period where the bears occupied the caves during the winter while the humans took over the caves in the summer. There also might have been intervals lasting several years between cave occupations by either group.
Since the oldest cave bear remains from the Chauvet cave date to 29,000 years ago, that supports prior claims that the charcoal drawings there are the oldest in the world.
In the journal paper, the authors explain: "Because painting an animal that is no longer present is hardly feasible, we propose that these red rock art pictures are indeed very ancient, dating back to the Aurignacian (a period lasting from 40,000 to 28,000 years ago)."
Archaeologist Jean-Michel Geneste, who is director of France's National Center for Prehistory, told Discovery News said the "results are important for the interpretation of the Aurignacian paintings."
Andrew Lawson, an archaeologist based in Salisbury, U.K., also supports the new findings. But Paul Pettitt of the University of Sheffield is skeptical that the Chauvet paintings are so ancient.
Pettitt believes their style is too advanced for the date given, likening them to a Renaissance painting found in a Roman villa. He further questions if the bears in the drawings are cave bears or brown bears, but Bon's team say the skull shapes for each species are unique.
Bon and her colleagues hope future studies will put a more firm date on when cave bears went extinct. The researchers also call for analysis of charcoal fragments spotted in the Chauvet cave places containing the cave bear remains.
© 2012 Discovery Channel