Michelle Dickinson: nanotechnologist on the new research revealing why polar bears are greasy

If you could cuddle a friendly polar bear, how do you think it would feel?  

Most people might guess soft and fluffy, but new research out this week in the journal Science Advances found that the answer is actually greasy! 

Polar bears are masters of survival in one of the harshest environments on Earth. With temperatures plummeting well below freezing and a habitat that consists largely of ice and water, these Arctic giants need every advantage they can get. We already know that their thick fat layer and dense fur keep them warm, but we didn't know until now that greasy hair might be one of their most powerful survival tools!.

The research found that the natural oils in polar bear fur prevent ice from sticking to it.  

Researchers collected fur samples from six wild polar bears and measured three key factors: 

• Ice Adhesion Strength – How easily does ice stick to the fur?
• Hydrophobicity – Does water bead and roll off before freezing?
• Freezing Delay Time – How long does it take for a droplet of water to freeze? 

The results were striking. When unwashed, polar bear fur resisted ice adhesion significantly better than human hair and synthetic ski skins. But when the fur was washed and stripped of its natural grease, it lost this anti-icing ability and behaved just like human hair—meaning ice stuck easily. 

The team performed a detailed chemical analysis of the polar bear’s fur grease (sebum) and identified a key mix of natural compounds—cholesterol, diacylglycerols, and fatty acids. These components work together to make the fur slippery, preventing ice from gaining a foothold. 

Interestingly, one common fatty substance—squalene—was notably absent. Squalene is found in human hair and in aquatic mammals like sea otters, but its lack in polar bears suggests it may actually hinder ice resistance.  

The benefits of this greasy fur go beyond just comfort. Polar bears rely on a hunting technique called 'still hunting,' where they patiently wait near a seal’s breathing hole in the ice. If the bear needs to slide silently into the water for a surprise attack, its ice-resistant fur helps minimise friction and noise. This quiet approach gives them a better chance of catching their prey. 

Nature has long been a source of inspiration for engineers and scientists. The way polar bear fur repels ice could lead to the development of new, more sustainable anti-icing coatings. These innovations might one day replace synthetic, long-lasting chemicals like PFAS, which are currently used in many industrial applications, but pose environmental concerns. 

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Episode Transcript

Speaker 1 (00:06):
You're listening to the Sunday Session podcast with Francesca Rudgin
from News Talks.

Speaker 2 (00:11):
It'd be doctor Michelle Dickinson joins me in the studio.
I can't believe we're talking about one of my favorite beers,
polar bears.

Speaker 3 (00:19):
Polar bears a Roman, good morning. I have a question
for you. Yes, you probably haven't cuddled a polar bear,
but everybody at home, if you're listening, if you were
to cuddle a friendly polar bear, think about how it
might feel. What do you think it's fur would feel like.
Ask your kids how it would feel and they'd probably
say soft and fluffy.

Speaker 1 (00:36):
Yes.

Speaker 3 (00:37):
So new research out this week in the journal Science Advances,
and it is an open source journal, so you can
go and look at it for free if you Want's
got some lovely pictures of polar beth and it has
found that they're not soft and fluffy at all. If
you were to cuddle a polar bear, it is really greasy.
And I hadn't thought about this, but this is the
first time it's been discovered. And they're greasy for a

(00:58):
really specific reason. So think about where polar bears live.
It's one of the harsher environments in the world. They're
a mammal, they need to stay warm. And we knew
that polar bears do this because they have thick fur
and they have a lot of fat, and that fat
keeps them warm. But what people hadn't thought about is
they're they're the only mammle that dive into the water

(01:18):
to fish and then come back out. And so if
we were to do that, not only would be cold
when we came back out, our hair would freeze because
the water on a hair would freeze. And somebody noticed
that polar bears fur doesn't freeze, and they're like, hold on, wait,
has neverody thought about this? So somebody took six different
samples of wild polar bear skin that were donated to

(01:38):
science and ran some really simple experiments on them. And
experiments where one was an ice adhesion test, how well
does ice stick to it? Number two was how hydrophobic
it is? So how well does water run off or
pull up? Hop puzzle? And third was is there a
freezing time delay? So how long if you get out
of the water does it take for your hair or
your fur to freeze. And what they found is polar

(02:00):
bears are amazing. They have basically fur that ice slides
off and ice can form one wow, and they found
that once they washed the polar bears for it had
the same properties as human hair. It's rubbish. So there's
something in the polar bears first, so they were like, well,
what could it be? And they did this chemical analysis
and basically it's grease. It's called sebum. We produce it.

(02:22):
How your hair gets greasy, They produce it. And they
chemically analyze the sea burn and found that it's exactly
the same as ours. Apart from so our hair has
got cholesterol in it, fatty acids, glyceols. There's one chemical
that's missing and it's called squalene. Now, squalene is a
fatty substance that's found in our hair. It's found in
most aquatic mammals, seotters for example. It was not there,

(02:46):
and they think the lack of squalene is what makes
this amazing grease that coats the polar bears, which stops
them number one having ice stick to it, but number
two makes them slide really well on ice. And they
need to do this because the way that polar bears
eat is they do something called still hunting where they
sit really patiently next to the breathing hole of a seal,

(03:07):
waiting for the breathing hole to be filled with the
seal and then they can slide really quickly but silently
because of this grease into the hole and get their
seal for their dinner.

Speaker 2 (03:17):
Oh and please don't tell me they stink as well?
Do they stink?

Speaker 3 (03:22):
So this grease is quite stinky because everything sticks to it.
Imagine yourself with really greasy hair adding not washed it
for two weeks. You don't smell great. Yeah that's your
polar bear. Pretty fishy, pretty stinky, not as soft and
fluffy as you might imagine.

Speaker 2 (03:34):
We disappointing, but you know that's the world. And television,
you know, you don't get the feel or the smell
on television. Of course, you grow up thinking polar bee
is a lovely and cuddley and so we can people
read about this.

Speaker 3 (03:45):
It's a journal Science Advance as it came out this week.
There's some lovely little pictures of like ice cubes that
they're trying to stick the fur to and some of
the different fur types. But yeah, it's a lovely open
source journal. And yeah, next time you look at a
polar bear in a docco just take a closer look
at its fur and that it's super greasy.

Speaker 2 (04:01):
And stinks, and yeah, that's fascinating good stuff. Thank you
so much, doctor Michelle Dickens, and enjoy the rest of
your Sunday. Thank you.

Speaker 1 (04:09):
For more from the Sunday Session with Francesca Rudkin. Listen
live to News Talks it B from nine am Sunday,
or follow the podcast on iHeartRadio.