There’s something about the smell of catnip that drives cats crazy. The plant it comes from, Nepeta cataria, is a herbaceous member of the mint family, native to Europe, Asia and the Middle East.
What does it do to cats?
Its aroma compels cats to sniff, lick and chew its flowers and leaves, rub their faces and bodies on the plant, shake their heads, roll around and drool. This frenzy of excitement usually lasts around 15 minutes – after that, they seem immune to its effects for around an hour.
But not all kitties respond to catnip: around 70 percent of cats go wild for its scent. Kittens show no interest, and neither do almost a third of adults. This is due to genetics: a dominant gene variant makes cats susceptible to the plant’s allure.
Why do cats like it?
The key chemical in Nepeta cataria is a compound called nepetalactone. It produces its effect through smell alone: the molecule doesn’t have to be ingested or get into the brain to send cats wild. Although some have suggested that cats experience a drug-like euphoria or hallucinations, there is no evidence for this. They do not become addicted or suffer any ill effects from the herb.
Advertisement
Cats affected by catnip display behaviour that’s similar to that of female cats in heat, but the plant affect males and females equally. Neil Todd, who wrote a PhD thesis on the response to catnip in 1963, suggested that it activates smell receptors for sex pheromones. However, no compound in cat urine has been identified that produces the same response as nepetalactone.
“The best explanation for the occurrence of an array of different behaviours to a catnip source, at this point, is that catnip activates different brain areas controlling female-like courtship, kitten-like play and predatory behaviour, at random,” write Benjamin Hart and Lynette Hart in their book Your Ideal Cat.
The fit between nepetalactones and cat smell receptors that evoke the behaviour seems to be an evolutionary accident. Cats that respond are native to the Americas, and would not have encountered the plant in their evolutionary history.
How big cats respond
Many big cats – including lions, leopards and jaguars – seem to be affected just like our domestic feline friend, and their habitat does not overlap with the plant either.
This description comes from a 1942 study testing the effects of nepetalactone in zoo lions: “They can be aroused immediately from a state of lethargy to one of intense excitement by the odour of the lactone, and will follow the odour to its source. When they acquire the material with the odour they become ludicrously playful and their main interest seems to be to get the odoriferous material transferred to their fur. They show no desire to eat the material, nor is there any evidence of sexual stimulation.”
Nepeta cataria plants do not make nepetalactone for cats’ benefit. Rather, they do it to protect themselves from aphids, which like to suck their sap. Nepetalactone is also a sex pheromone produced by aphids. By producing the pheromone, the plant attracts aphid predators such as the lacewing fly.
Other uses
Humans have also sought to make use of catnip as an insect repellent: it seems to help keep away mosquitoes, flies and cockroaches.
In 1969, a paper in the Journal of the American Medical Association reported that people were smoking catnip to get an effect similar to marijuana. However, readers soon pointed out that the two plants had been mixed up – at least in the paper’s illustrations. Humans seeking a high by smoking catnip will be sorely disappointed.
Interestingly, mice produce lactones – molecules similar to nepetalactone – in their sweat. Hart and Hart suggest that they have evolved them as a “magic potion” to distract cats when they are caught. This might explain why cats often bat around and play with mice, just as they do with toy mice stuffed with Nepeta cataria leaves.
Finally, the most bizarre effect of this multifaceted molecule: nepetalactone has been found to enhance erections in rats. Sam Wong
