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Of the many bewildering behaviors cats display, one of the strangest is their obsession with a specific species of plant. After just one whiff, even the most stoic cat can start pawing, drooling, biting, and wriggling in a state of pure feline euphoria. So, why do cats go crazy for catnip? This is the question cat behavior expert Masao Miyazaki and chemist Toshio Nishikawa set out to answer in 2013. Along with their research teams from Iwate and Nagoya University, they began by studying silvervine- a plant that sparks a similar response to catnip.
First, the researchers painstakingly extracted chemical compounds from the plant and dribbled various combinations of them onto filter papers. Then they brought in some cats and studied which compounds they were drawn to. Overwhelmingly, their feline testers pounced on the papers containing nepetalactol. And when Miyazaki and his student Reiko Uenoyama ran blood tests on the cats who'd interacted with nepetalactol, they found their systems were flooded with endorphins. These hormones block pain signals, relieve stress, and generally create a happy, calming effect. And catnip triggers the same endorphin rush with a similar chemical called nepetalactone, and it's this flood of happy hormones that gives catnip and silvervine
their signature drug-like response. These compounds don't just trigger this effect in small cats. When the researchers brought nepetalactol-treated filter papers to a few zoos, leopards, lynxes, and jaguars all dove face first into the compound. This was big news. If all these different cat species reacted to nepetalactol in the same way, the response was very likely a shared evolutionary trait- potentially something important to cat survival that stretched back millions of years. When the silvervine researchers presented their work at a conference, one evolutionary biologist raised a compelling theory. In chemical terms, both nepetalactol and nepetalactone are classified as an iridoid-
a type of natural compound known to contain insect-repelling properties. So perhaps cats rubbing their faces in silvervine and catnip were applying an ancient form of bug spray. To test this, researchers set up cages of mosquitoes that cats could stick their heads into. And sure enough, the cats that had been treated with nepetalactol got fewer mosquito bites than the cats in the control group. The same effect was true for the scientists who'd volunteered their arms in solidarity with their feline subjects. These mosquito-repelling properties are currently our best explanation for why cats love silvervine and catnip.
But researchers still had one more question: in their state of euphoria, cats tend to vigorously bite, lick, and rub against these plants. But do cats really need to go this crazy to get their bug repelling effects? To investigate rubbing, they provided cats with filter papers treated with microscopic amounts of nepetalactol. And sure enough, even these tiny doses made the papers irresistible, suggesting that microscopic amounts of bug repellent can be transferred by rubbing alone. As for biting and licking, the researchers found that when cats damage the plant, the leaves actually produce more mosquito-repellent chemicals. So your cat isn't just ripping open their bags of catnip to be annoying,
their evolutionary instincts are just trying to get even more of that bug protection. Cats are far from the only animal to use natural plants for purposes like this. Apes swallow scratchy and hairy leaves to dislodge parasites from their guts. Sheep munch on tannin-rich plants to kill intestinal worms, and monarch butterflies use toxic milkweed to kill parasites that normally impair their flight. Just like cats' ability to find mosquito repellent, these behaviors can help humans identify useful plants and ingredients in the natural world. So, the next time you see your feline friend on catnip binge, don't worry- it's only medicinal.
