Why Bearcats Smell Like Buttery Popcorn

A shy, shaggy-haired animal from Southeast Asia forever smells like hot buttered popcorn, and now new research reveals why.

The animal, known as a bearcat or binturong, naturally produces the exact same compound that gives popcorn its tantalizing aroma. The findings are publishing in the latest issue of the journal Naturwissenschaften (The Science of Nature).

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"The fact that the compound was in every binturong we studied, and at relatively high concentrations, means it could be a signal that says, ‘A binturong was here,' and whether it was male or female," co-author Lydia Greene, a graduate student at Duke University, said in a press release.

In short, the smell is probably just as enticing to bearcats as it is to hungry humans at a movie theater.

The scientists made the discovery during routine physical examinations of 33 bearcats at the Carolina Tiger Rescue, a nonprofit wildlife sanctuary in Pittsboro, North Carolina. Bearcats are carnivorous, endangered, forest-dwelling mammals that are long and stocky with relatively short legs.

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During the exams, the researchers collected and analyzed bearcat urine samples. They used a technique called gas chromatography-mass spectrometry, which allows complex mixtures of chemicals to be separated, identified and measured.

The scientists identified 29 chemical compounds in the animals' urine. The one compound that emanated potently from every sample was 2-acetyl-1-pyrroline, or 2-AP. It is the exact same compound that gives popcorn its yummy smell.

The compound 2-AP normally forms in popcorn during the popping process, when heat initiates reactions between sugars and amino acids in the corn kernels. The cooking produces a variety of new odor and flavor molecules in a chemical reaction called the Maillard reaction. The same compound is also responsible for the comforting aromas of toasted bread and cooked rice.

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The multi-step process humans require to produce the compound had the researchers questioning the bearcat's remarkable odor-producing capability.

"If you were to make this compound, you would have to use temperatures above what most animals can achieve physiologically," project leader Christine Drea, a professor of evolutionary anthropology at Duke University, said. "How does this animal make a cooking smell, but without cooking?"

In captivity, bearcats eat kibble, so the scientists looked for the unique compound in such food. They could not detect the compound in it, though.

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The scientists now think that 2-AP is produced when bearcat urine comes into contact with bacteria and other microorganisms that live on the animal's skin or fur, or in its gut. A time-release factor inherently results from the process, allowing the scent to last longer.

Drea explained that bacteria make smelly compounds as they break down sweat in our armpits in much the same way.

The bearcats seem quite proud of their odor. They release their popcorn-scented urine while in a squatting position, soaking their feet and bushy tails in the process. They then drag their tails as they move about in the trees, leaving a scent trail on the branches and leaves behind them.

The resulting popcorn-scented urine "smell-o-gram," as the researchers refer to it, lasts long after the animals move along. The authors note that it provides an essential mode of communication - marking territory and helping to attract mates - for these otherwise relatively solitary animals.

A bearcat, also known as a binturong, at the Rare Species Conservation Center in the U.K.