Polar, Brown Bear Ancestor ID'd From Cave Bones

Oct. 28, 2008 -- The ancestor of two main species of bear lived around 1.6 million years ago, according to analysis of bones found in the Chauvet Cave in southern France, better known for its dazzling examples of Stone Age artwork.

Well-preserved bear bones found in the cave were carbon-dated to 32,000 years before the present day, French researchers said in a study published on Monday.

Cave bears (Ursus spelaeus) lived in Europe and the Middle East from around 300,000 years ago to around 15,000 years ago, when they became extinct, they said.

The scientists also teased out pieces of so-called mitochondrial DNA -- material passed down on the maternal side -- from the bones and reassembled the sequence.

They then used this sample to calculate the species' history, using a method called the molecular clock, based on a regular rhythm of genetic change.

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The cave bear was a sister to the brown bear and /news/slideshows/baby-polar-bear.htmlpolar bear, and all descended from a common ancestor that lived around 1.6 million years ago, the investigators found.

The paper, by a team from the Institute of Biology and Technologies at France's Atomic Energy Commission (CEA), appears in the journal Proceedings of the National Academy of Sciences (PNAS).

It is the first time that mitochondrial DNA has been recovered from subterranean remains of prehistoric animals.

The trick has been carried out on woolly mammoths and mastodons, whose remains were found in Siberian permafrost, and on the flightless New Zealand bird, the moa, which was wiped out several hundred years ago.

Caves, while less favorable than deep cold as a form of preservation, ensure stable temperatures, of 12-15 degrees Celsius (53.6-59 degrees Fahrenheit) and are sheltered from ultraviolet light.

"Our study ... demonstrates the feasibility of retrieving complete mitochondrial genomes from the subterranean milieu, an environment that contains remains for a variety of extinct species," the study says.

The Chauvet Cave, located in the Ardeche region of southern France, has the oldest-known cave paintings, with handprints and depictions of horses and other animals dated to around 30,000-32,000 years ago.

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