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Polar Bears (excerpt from Sustaining Life)


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Polar Bears (Ursus maritimus) are threatened by habitat destruction, human encroachment, and by exposure to persistent organic pollutants (they are at the top of the marine food chain and tend to concentrate these toxic chemicals in their tissues). But the greatest threat to them is from the melting of sea ice due to global warming, because large areas of open water make it possible for seals, Polar Bears’ main food, to elude capture when surfacing for air.

Many have responded with anguish to predictions that these magnificent creatures, Earth’s largest land carnivores, will become extinct in the wild within this century, but few are aware of their value to human medicine.

Unlike all other mammals, Polar Bears and other hibernating bears do not lose bone mass despite periods of 7 months or more of immobility. We lose more than 1/3 of our bone when we are immobile for that long. If we knew how the bears accomplished this, we could perhaps synthesize new, more effective medicines to treat osteoporosis, a disease that causes 750,000 deaths each year worldwide and costs the global economy about 130 billion U.S. dollars.

Polar Bears don’t urinate during the several months of hibernation and yet don’t become ill. If we cannot rid our bodies of urinary wastes for several days, we die. If we understood how hibernating bears did this, we might be able to develop better treatments for kidney failure, that each year, in the U.S. alone, kills 80,000 people and costs the economy $27 billion. More than 1 million people with kidney failure around the world are currently being kept alive by renal dialysis, a number that is expected to double in the next decade.

Polar Bears become massively obese prior to entering their dens and yet do not develop Type II diabetes, as we humans tend to do when we become obese. More than 20 million people in the U.S. today have obesity-related Type II diabetes, some 7% of the population, and a quarter of a million of them die from this disease each year. Type II diabetes is also increasing rapidly in many other countries, with some 250 million people affected worldwide.

If we lose Polar Bears in the wild, we may lose with them the secrets they hold for our being able to treat, and possibly even prevent, osteoporosis, kidney failure, and obesity-related Type II diabetes, three human diseases that kill millions each year and cause enormous human suffering. 

Aaron Bernstein, MD, MPH

Aaron Bernstein is the Interim Director of The Center for Climate, Health, and the Global Environment, a pediatrician at Boston Children’s Hospital, and an Assistant Professor of Pediatrics.

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