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Polar bears spend their days jumping from ice into water. So if they get all wet, why doesn't their fur freeze? Well, a recent study in the journal Science Advances investigated that very question, and NPR's science correspondent Jonathan Lambert has the details.
JONATHAN LAMBERT, BYLINE: Nanophysicist Bodil Holst got interested in studying polar bear fur while watching a German quiz show.
BODIL HOLST: In that quiz show, I learned that polar bears are invisible in infrared cameras.
LAMBERT: That essentially means that they're so well insulated that their fur takes on the temperature of their frigid surroundings. That's the case on land and when they jump into icy water to hunt.
HOLST: Because I had been working with anti-icing, I just suddenly was very puzzled because I was thinking, well, how do they manage that? When they get into the water and they come out again, why do they not get covered in ice?
LAMBERT: Meaning they stay cold, but their fur is largely free of ice. Holst, who's at the University of Bergen in Norway, initially thought that the structure of the fur itself might have some kind of deicing properties. So her team used a high-powered microscope and zoomed in on some fur.
HOLST: But we couldn't see anything special about the polar bear hairs. They just looked normal.
LAMBERT: But as she and her colleagues were handling the fur, they noticed that it was really greasy. And when they washed the fur with soap, wet it and froze it, it got icy.
HOLST: And so we realized that this was down to polar bear hair grease, effectively.
LAMBERT: Molecular analysis of the hair grease revealed that it was chock-full of certain compounds which are resistant to ice, and the fur lacked a compound called squalene, which is found in other marine mammals. Squalene, it turns out, has properties that make ice stick to it.
HOLST: We can say that this is what makes polar bear hair grease so efficient.
LAMBERT: In fact, the team found that the squalene-free fur grease performed about as well as certain kinds of PFAS chemicals that have been used in ski waxes. Finally, to bring it all together, one of Holst's students took it one step further.
HOLST: Didn't wash his hair for quite some time and then shaved and made a little mat of his own greasy hair and tried to test the anti-icing properties and could see very clearly that human hair, whether you wash it or not, is not very good at anti-icing.
LAMBERT: Holst hopes that her research could eventually lead to things like greener ski waxes, lubricants and even new deicing fluid for airplanes, all inspired by greasy polar bear fur.
Jonathan Lambert, NPR News.
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