Part of the show Search for Extraterrestrial Life
Black Bears seem to be unique amongst hibernating animals because they have the unique ability to stop their bones from thinning during their long winter sleep, suggesting that they may hold the key to preventing bone thinning diseases, like osteoporosis, in humans. Usually, any period of prolonged inactivity, without weight-bearing exercise, including being immobile, elderly or even going into space, can lead to significant bone loss. But by studying the metabolism of hibernating bears, Seth Donahue and his colleagues from Michigan Technological University have found that, unlike people and other animals, bears keep laying down new bone even when they are inactive. The researchers think that this is because, unlike most hibernating animals, bears don’t urinate or defecate so they have no way to get rid of waste calcium from the body – so instead they put it into their bones. To find out how they do this the researchers are now looking for differences between humans and bears amongst some of the key hormones that regulate bone density and calcium metabolism. This may lead to new therapies for the prevention or reversal of human bone loss. Osteoporosis is a serious problem with 50% of women and 25% of men over the age of 50 suffering a fracture because of it.