Researchers identify a surprising urinary compound.
Though it is neither a cat nor a bear, its name is not the strangest thing about this rare civet from Southeast Asia. The bearcat, also known as binturong, produces urine with a surprisingly pleasant aroma that is reminiscent of a movie theater lobby.
This popcorn-scented urine is likely an important means by which bearcats communicate. Being solitary mammals, bearcats rarely encounter one another. Rather, they soak their feet and bushy tails in puddles of their urine, leaving scent trails on branches and leaves as they move through trees. Indeed, animals often use similar forms of chemical communication to mark their territory, attract mates, find prey, and identify other animals.
In a recent study published in the journal The Science of Nature – Naturwissenschaften, researchers analyzed the urine of 33 bearcats inhabiting a wildlife sanctuary in Pittsboro, North Carolina. Using gas-chromatography mass-spectrometry, a technique often used to identify chemicals within a test sample, the researchers were able to isolate 29 different compounds in bearcat urine. Among these compounds was one called 2-acetyl-1-pyrroline (2-AP), which is responsible for popcorn’s appetizing aroma.
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The compound 2-AP is produced when popcorn is heated, which triggers reactions between sugars and amino acids in the corn kernels. This same compound is also present in toasted bread and cooked rice. Importantly, the chemical reaction required to produce this compound, called the Maillard reaction, requires extremely high temperatures.
"If you were to make this compound, you would have to use temperatures above what most animals can achieve physiologically," said Professor Christine Drea from Duke University who led the study. "How does this animal make a cooking smell, but without cooking?"
One possibility is that something the bearcats eat is responsible for the odor of their urine. But a careful examination of their diet yielded no trace of the 2-AP compound. Instead, the researchers propose that microorganisms found on the animal’s skin and fur or in its gut might interact with the urine to produce 2-AP.
The researchers were also interested in what types of information bearcats might glean from sniffing these urine scent trails. “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," said first author Lydia Greene, a graduate student at Duke University.
Surprisingly, bearcats are not the only animals known to produce excretions that smell like tasty treats. Beavers secrete a vanilla-scented compound from their anal glands that is used to flavor some baked goods and candy. The western spadefoot toad produces a peanut butter-scented substance that will also cause you to sneeze.
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