A new international study found surprising properties of the natural oils on polar bear fur. The first use will be in ski wax but airplanes, fridges, and air conditioners may also benefit.
You have probably seen it on video: polar bears sliding down hills as if their fur was slippery as a bobsled. Or even gliding on their stomachs over thin ice or diving into freezing water as they hunt.
All of these behaviors are made possible by a special feature of their fur: even in temperatures well below zero, it does not freeze like the fur of other mammals.
Until very recently the reasons behind – and the possible applications of – this property of polar bear fur have remained obscure. But now, with a new international study led by PhD-student Julian Carolan from Trinity College, Dublin, new light has been shed on what exactly makes polar bear fur so special.
And the reasons, it turned out, were entirely different than the researchers first thought.
“We went into it thinking the reason was the structure of the polar bear hairs, like the structure of penguin feathers is the reason they don’t freeze. But as we looked into it, it turned out that it wasn’t structural at all. Polar bear hairs are very much like human hairs under a microscope,” Julian Carolan, whose background is in chemistry, told Polar Journal AG.
The natural oils on the fur
But even though their first hunch turned out to be wrong, Julian Carolan and his colleagues knew they were on to something.
They had obtained polar bear hair samples which had been gathered on Svalbard from the Norwegian Polar Institute. Initial measurements of these hairs did, indeed, show that they had much lower adhesion than the hairs of other mammals.
But the answer could not be found in the microstructure, as Julian Carolan had expected.
“On one hand, I had kind of hoped the cause had been structural. When you are trying to copy that you get to do some cool 3D-printing. So when we first discovered that it wasn’t I thought it was a bit of a shame,” he said.
Instead, Julian Carolan and his colleagues had to take a step back and consider what else could be involved.
“At this point, we asked ourselves: ‘okay, what else can we vary?’ It was only then that we started looking at the oils on the polar bear hair,” Julian Carolan said.
And the chemical composition of the hair oil turned out to be the jackpot. In a simple experiment, the researchers observed that once the hair oil was washed off, the low adhesion was no longer present. They had found their solution.
“When I then started to look at these oil structures I realized that this is probably even more interesting than if it had been structural. Suddenly, I was looking into something that very few people had studied,” he said.
Squalene causes freezing
In fact, it was the absence of a particular chemical compound that proved to be significant. Squalene is an oil that is present on the hair of most mammals (at least the ones that have been studied), but the researchers did not find it in the polar bear hair oil at all.
“All the aquatic mammals previously studied had squalene in their hair – animals that go in and out of water like otters, sea lions, and beavers, for instance. But polar bears didn’t,” Julian Carolan said.
“Human hair is also rich in squalene which is why you get all this ice build-up on beards,” he said.
Aside from identifying squalene as very conducive to ice build-up, the study made an even more important discovery. One that might lead to the development of new anti-icing technology.
“We found three polar bear oil molecules that stuck very weakly to ice in our simulations. These molecules may be used in other applications and are the primary finding of this study,” Julian Carolan said.
Clued in by indigenous knowledge
One important clue that led the researchers to consider the oil rather than the microscopic structure of the hair was the inherited knowledge of the Inuit. Because, for as long as anyone can remember, the Inuit have known about the special anti-freezing feature of polar bear fur.
The Danish ethnographer Erik Holtved, for instance, noticed this during his extensive trips to northern Greenland in the 1930s. His work describes how local Inuit people would not wash the fur when they had encountered and killed a polar bear.
Instead, they would use the non-freezing material in a variety of ways, including both polar bear fur hunting stools and sandals that would allow them to move through the snow in silence.
Examples of these old polar bear fur tools still exist at the National Museum of Denmark, and the international research team behind the polar bear fur study used them both in their research and in their final publication.
“Early on, the idea to look at the hair oils came partially because of these historical documents. And then towards the end of the study, we started to correlate the possible uses of these molecules with how the Inuit had traditionally used them,” Julian Carolan said.
A patent on ski wax
And, with the new study, this ancient Inuit knowledge about polar bear fur may find applications in the modern world.
So far, though, the study has only worked with simulated substances on a computer. A lot still has to be tested with real chemical compounds in the real world. Julian Carolan, is currently in the process of conducting these tests, and according to him, the first indications are promising.
The most obvious use of the new knowledge is in ski wax for cross country skiing. In the past few years, fluorinated waxes have been banned across the US and the EU after the discovery that they may contain dangerous PFAS chemicals. Therefore, the demand for a replacement wax is high and the polar bear skin oil (or the knowledge obtained from it) may provide just that.
Some of Julian Carolan’s colleagues have thus already obtained a patent for a ski wax based on the newly discovered compounds.
“This is the most obvious use case. We just need to make the right cocktail of wax and get all the viscosity and adhesiveness right. So I think that will be the first place to use them,” he said.
Beyond that, the new compounds may help in other problems caused by ice build-up. Julian Carolan mentions issues such as icing on airplanes, in freezers and fridges, in air conditioners, and even on wind turbines.
“There are two ways the compounds may be used. Either you can create a wax and spread them on or you can chemically bind them to the surface. Both have advantages and disadvantages and I am currently testing how they’ll work best,” he said.
Should he discover a profitable application of these anti-icing compounds, Julian Carolan is not opposed to turning it into a business venture. And if he does get that far, he has some calming words for those concerned about the plight of polar bears: now that the study is completed, their fur is no longer needed.
“There is no need for the polar bears anymore. The three anti-icing molecules that we found can be bought off the shelf, and we can make them ourselves,” he said, assuringly.
Ole Ellekrog, Polar Journal AG
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