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The binturong is hard to describe. It is sometimes called a "bearcat," but it isn't closely related to bears or cats. And it smells like popcorn, but the source of that smell is not good eats.

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Communication is pretty central to the whole human experience.

Over millennia, we have, for example, created specific mouth-sounds that go with particular brain-pictures that we can share with other people. I’m doing it with you right now.

And one of the things we do as humans in order to communicate is give things names. Now, usually when we encounter something new or different or strange, we tend to describe it in terms that are familiar to us. But, sometimes, the thing we are trying to describe is just way more bizarre than we can put into words. [ ♪ Intro ].

Take, for example, the binturong. I look at this thing and my brain says, “bear.” And then I look at it again and my brain goes, “bear?” But then the whiskers say, “cat,” as does the way they kind of purr, but the face... doesn’t? My brain just fails to categorize this thing.

And it appears that I’m not alone in this confusion, because the binturong is often called the “bear-cat” and its genus name, Arctictis is Greek for “bear-weasel.” But it is NONE of those things, not a bear, not a cat, and not a weasel. It’s not even particularly closely related to any of them. And it’s not filling the bear niche, either.

Where it lives, sun bears do that. It’s a mammal in the family Viverridae and the only thing in its genus. The other members of this family include the civets and genets, which, okay, do kinda look like weasels, with their relatively long, skinny bodies and short legs.

But the binturong is even less weasel-y looking, think more wolverine than ferret. They’re the largest of the viverrids, weighing up to around 20 kg or so, and the females are 20% bigger than the males. Viverrids are part of the order Carnivora, but they’re on the side of that group that’s more closely related to cats than to dogs, bears, and weasels.

So, the “cat” part of “bear-cat” was the most correct part, but also still a big miss. You can find viverrids throughout Africa, in South and Southeast Asia, and in parts of southern Europe. The binturong, though, is only native to the forests of Southeast Asia, where they spend most of their time in the trees.

So picture this: you’re walking through the jungle and you catch a whiff of hot buttered popcorn. That doesn’t seem right. Hot buttered popcorn is for movie nights, not for jungle walks.

Who is making popcorn in the jungle? No one! Because you didn’t just smell popcorn, you smelled binturong.

Or, more specifically, you’ve just smelled their pee. Binturong urine naturally contains a compound called 2-acetyl-1-pyrroline, or 2-AP, that is also produced in popcorn when it undergoes the Maillard reaction at high temperatures. The Maillard reaction is a chemical reaction that takes place between certain sugars and amino acids during cooking, it’s what makes both a toasted marshmallow and a grilled steak brown and delicious.

And that 2-AP is probably responsible for the binturong’s scent. So I have not eaten buttered popcorn for 15 years because of my chronically diseased colon, but buttered popcorn jelly beans are another story. I have had those.

So I was wondering whether the compound that gives them their buttery flavor is the same thing that is in binturong pee. Turns out, no, it’s not. Artificially butter-flavored things are usually made with diacetyl, which is not the same as the 2-acetyl part of 2-AP.

Diacetyl means there are 2 acetyl groups. Whereas the 2 in 2-acetyl-1-pyrroline refers to the location of the acetyl group. Check out Crash Course organic chemistry if you want more of this kind of spellbinding content! 2-AP is, however, the compound that creates the smell of warm basmati rice and white bread.

But Binturongs create MORE of it, and apparently the quantity manages to push it into popcorn territory. Diacetyl actually just tastes like butter, more than popcorn. So it’s fair to say that binturong urine actually smells more like popcorn than popcorn jellybeans.

Anyway, the reason why binturong urine smells like a concession stand is probably about communication. There, we got back around to it in the end, didn’t we. See binturongs are solitary, so they use scent-marking to leave signals behind for other binturongs.

They do have scent glands, but their pee is really what gives them that delightful popcorn smell. Basically, they pee on their feet and their tails, then go about their business, climbing slowly through the forest canopy with the help of their prehensile tails, leaving their stinky little messages behind. By the way, out of the 270 species of Carnivora, there are only two with prehensile tails, the binturong and the kinkajou, and those two species are not related at all.

And that popcorn scent lasts, as the scientists who did the pee study learned when their frozen urine shipment was delayed in transit and arrived as not-frozen urine. While both male and female binturongs produce 2-AP, males seem to have more of it in their pee than females, so it probably contributes to letting other binturongs know the sex and reproductive status of an individual. Which is kind of important for a lonely binturong to know.

But how the binturong makes 2-AP is still a mystery. They definitely don’t run hot enough for the Maillard reaction to be happening, like, inside of their bodies and the researchers studying their pee can’t find any significant amount of 2-AP in their food, either. So, they think it’s most likely a normal product of fermentation made by microbes that live in the binturong’s gut.

And what those gut microbes are breaking down varies. While binturongs are part of the order Carnivora, most of their diet is actually made up of fruit, especially figs. They’re willing to eat pretty much anything they find though, bugs, rodents, eggs, you name it.

All that fruit-eating makes them important seed dispersers for the forests they live in as they move through their habitat, they poop out the seeds of the fruits they eat in different places, helping the forest replant itself. These non-bear-cat-weasels, with their popcorn-smelling pee and adorably confusing looks, definitely qualify as bizarre beasts. And while our brains and words may have failed at communicating what they really are, the binturong’s method of getting their message across seems to be working out just fine.

The Bizarre Beasts pin club is open now through the end of September 6th for new subscribers! When you sign up, you’ll get the binturong pin in the middle of the month, and then the ones after that around the time each new video goes live. The binturong pin is very cute.

I like it so much. And for the full binturong experience, feel free to pop some popcorn and smell all that 2-AP when your pin arrives. We’ll be posting some extra facts that didn’t make it into the video on our socials and we’d love to see folks show off their pins!

Follow us on Twitter @BizarreBeasts, and on Instagram and Facebook at BizarreBeastsShow. And profits from the pin club go to support our community’s efforts to decrease maternal mortality in Sierra Leone. [ ♪ Outro ].