The latest bad news for polar bears focuses on a potential link between low-density penis bones and polychlorinated biphenyls (PCBs). A team of researchers out of Denmark studied the penis bones or baculums of nearly 300 polar bears born between 1990 and 2000, identifying the potential link and noting that less dense penis bones could prevent successful mating. The same Danish researches previously showed that polar bears with high levels of pollutants in their bodies had smaller testes and a smaller penis bone. With two-thirds of polar bears projected to disappear in the next 35 years as a result of climate change induced habitat destruction, we're stacking the deck against long-term polar bear survival.
But wait, we don't use PCBs anymore, right, so what's the problem? Yes, PCBs were generally banned in 1979 (with certain phase outs and exemptions) for very good reason--they're super toxic--but they and other pollutants last a long time and tend to concentrate in certain regions, like the Arctic, where they build up over the years in the tissue of animals. As apex predators, PCBS and other pollutants build up in polar bears after they feed on animals (seals), that themselves absorb and store pollutants in their fat as they feed on contaminated fish. It's the same idea behind high concentrations of mercury in swordfish and sharks and why people warn pregnant and nursing women to avoid eating fish high in mercury.
It's not clear yet how these reproductive changes are impacting polar bears, if at all. Scientists still aren't sure what function the penis bone plays, especially as not all mammals have them (its absent in humans, rabbits, elephants, whales and dolphins, but apparently still making a difference for gorillas, cats, dogs, walruses, and mice). Regardless, bears have them and human-induced impacts that muck around with the results of evolution doesn't seem like the best news for a species facing extinction.
Nonetheless, we continue to muck around. Either through "baked-in" pollutant impacts resulting from toxic chemicals we pushed into the environment decades ago to our not-so-natural selection of bears for their skins to decorate our homes. Polar bear skins are big business (people also sell their skulls, teeth, and claws), with some fetching more than $20,000 dollars at auction last year in Canada--Canada is the only country that allows polar bears to be killed for international commercial trade. Prices depend on size and color, so that's what hunters keep in mind when they seek out bears to kill. They don't go after the old or sick, the way natural selection does, inflicting a different kind of harm on polar bears by undermining and potentially weakening populations that need to maintain their strength to survive the continued destruction of their environment.
We can't do much to strip pollutants out of the Arctic that are already there, but we can take steps to limit future pollutants--an issue NRDC has long been concerned about and has been raising with regulatory agencies--and we can end the international commercial trade in polar bears. It seems the least we can do for a species we're driving to extintion. The funny headlines are plentiful, but what's happening to polar bears now and what's going to happen to them in the future is less than humorous.
"Marco!" image by ucumari via Flickr
polar bear image by alkiol vi Flickr