Why bearcats smell like popcorn

The animal kingdom now harbors one fewer mystery. Researchers have ferreted out why the binturong, a threatened Southeast Asian mammal also known as the bearcat, smells like popcorn. The culprit is 2-acetyl-1-pyrroline, or 2-AP, the same molecule that gives cooked popcorn its aroma. Researchers led by Christine M. Drea of Duke University and Thomas E. Goodwin of Hendrix College found the compound by examining urine samples from 26 bearcats using gas chromatography/mass spectrometry (Sci. Nat. 2016, DOI: 10.1007/s00114-016-1361-4). The team observed 2-AP in each urine sample, from males and females alike, Drea notes. The researchers also found that 2-AP concentrations correlate with androstenedione levels in a bearcat’s blood. Androstenedione is a hormone precursor to both estrogen and testosterone, leading the researchers to posit that bearcats use their urinary popcorn smell to communicate their sex and sexual maturity. This discovery does present a new mystery though: How do bearcats make this molecule? Popcorn gives off 2-AP via the Maillard reaction as a consequence of the high heat of cooking. “But nobody’s heating the binturongs up to hundreds of degrees,” Goodwin says. The team speculates that microbes may help the animals produce the aroma.