How Does Catnip Work?

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iStock

If you have a cat, you probably keep a supply of catnip at home. Many cats are irresistibly drawn to the herb, and respond excitedly to its scent, rubbing against it, rolling around on the floor, and otherwise going nuts. There are few things that can get felines quite as riled up as a whiff of catnip—not even the most delicious treats. But why does catnip, as opposed to any other plant, have such a profound effect on our feline friends?

Catnip, or Nepeta cataria, is a member of the mint family. It contains a compound called nepetalactone, which is what causes the characteristic catnip reaction. Contrary to what you might expect, the reaction isn’t pheromone related—even though pheromones are the smelly chemicals we usually associate with a change in behavior. While pheromones bind to a set of specialized receptors in what’s known as a vomeronasal organ, located in the roof of a cat's mouth (which is why they sometimes open their mouths to detect pheromones), nepetalactone binds to olfactory receptors at the olfactory epithelium, or the tissue that lines the mucus membranes inside a cat’s nose and is linked to smell.

Scientists know the basics of the chemical structure of nepetalactone, but how it causes excitement in cats is less clear. “We don’t know the full mechanisms of how the binding of these compounds to the receptors in the nose ultimately changes their behavior,” as Bruce Kornreich, associate director of the Cornell Feline Health Center, tells Mental Floss. Sadly, sticking a bunch of cats in an MRI machine with catnip and analyzing their brain activity isn’t really feasible, either from a practical or a financial standpoint, so it’s hard to determine which parts of a cat’s brain are reacting to the chemical as they frolic and play.

Though it may look like they’re getting high, catnip doesn’t appear to be harmful or addictive to cats. The euphoric period only lasts for a short time before cats become temporarily immune to its charms, meaning that it’s hard for them to overdo it.

“Cats do seem to limit themselves," Michael Topper, president of the American Veterinary Medical Association, tells Mental Floss. "Their stimulation lasts for about 10 minutes, then it sort of goes away.” While you may not want to turn your house into a greenhouse for catnip and let your feline friend run loose, it’s a useful way to keep indoor cats—whose environment isn’t always the most thrilling—stimulated and happy. (If you need proof of just how much cats love this herb, we suggest checking out Cats on Catnip, a new book of photography from professional cat photographer Andrew Martilla featuring dozens of images of cats playing around with catnip.)

That said, not all cats respond to catnip. According to Topper, an estimated 70 percent of cats react to catnip, and it appears to have a genetic basis. Topper compares it to the genetic variation that causes some individuals to smell asparagus pee while others don’t. Even if a cat will eventually love the smell of catnip, it doesn’t come out of the womb yearning for a sniff. Young kittens don’t show any behavioral response to it, and may not develop one until several months after birth [PDF].

But some researchers contend that more cats may respond to catnip than we actually realize. In one 2017 study, a group of researchers in Mexico examined how cats might subtly respond to catnip in ways that aren’t always as obvious as rolling around on the floor with their tongue hanging out. It found that 80 percent of cats responded to catnip in a passive way, showing decreased motor activity and sitting in the “sphinx” position, an indicator of a relaxed state.

There are also other plants that have similar effects on cats, some of which may appeal to a wider variety of felines than regular old catnip. In a 2017 study in the journal BMC Veterinary Research, researchers tested feline responses to not just catnip, but several other plants containing compounds similar in structure to nepetalactone, like valerian root, Tatarian honeysuckle, and silver vine. They found that 94 percent of cats responded to at least one of the plants, if not more than one. The majority of the cats that didn’t respond to catnip itself did respond to silver vine, suggesting that plant might be a potential alternative for cats that seem immune to catnip’s charms.

Despite the name, domestic cats aren’t the only species that love catnip. Many other feline species enjoy it, too, including lions and jaguars, though tigers are largely indifferent to it. The scent of the plant also attracts butterflies. (However, no matter what you’ve heard, humans can’t get high off it. When made into a tea, though, it reportedly has mild sedative effects.)

The reason Nepeta cataria releases nepetalactone doesn’t necessarily have to do with giving your cat a buzz. The fact that it gives cats that little charge of euphoria may be purely coincidental. The chemical is an insect repellant that the plant emits as a defense mechanism against pests like aphids. According to the American Chemical Society, nepetalactone attracts wasps and other insect predators that eat aphids, calling in protective reinforcements when the plant is in aphid-related distress. That it brings all the cats to the yard is just a side effect.

Because of this, catnip may have even more uses in the future beyond sending cats into a delighted frenzy. Rutgers University has spent more than a decade breeding a more potent version of catnip, called CR9, which produces more nepetalactone. It’s not just a matter of selling better cat toys; since catnip releases the compound to ward off insects, it’s also a great mosquito repellant, one that scientists hope can one day be adapted for human use. In that case, you might be as excited about catnip as your cat is.

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Thursday’s Best Amazon Deals Include Guitar Kits, Memory-Foam Pillows, and Smartwatches

Amazon
Amazon
As a recurring feature, our team combs the web and shares some amazing Amazon deals we’ve turned up. Here’s what caught our eye today, December 3. Mental Floss has affiliate relationships with certain retailers, including Amazon, and may receive a small percentage of any sale. But we only get commission on items you buy and don’t return, so we’re only happy if you’re happy. Good luck deal hunting!

Why Do We Celebrate Christmas on December 25?

If Jesus wasn't born on December 25, does this rule still apply?
If Jesus wasn't born on December 25, does this rule still apply?
Jon Tyson, Unsplash

Each December, Christians throw a collective birthday bash to celebrate the anniversary of Jesus’s arrival on Earth. But without a birth certificate—or any other official record of his actual birthdate—in existence, December 25 seems like an arbitrary day for all our Christmas traditions. So how did early observers choose it?

When Was Jesus Really Born?

Since the Bible doesn’t name a month or even a season for Jesus’s birth, historians have relied on other context clues to estimate when it occurred. Shepherds tend sheep in the Nativity story, which people often cite as evidence that Jesus was more likely born during the spring. Others argue that Israel’s mild winter temperatures allow sheep to graze even in December. According to Slate, it’s also possible that sheep set aside for religious sacrifices may have been given free rein, frigid night or not.

The Adoration of the Shepherds by Sebastiano Conca, 1720.J. Paul Getty Museum // Public Domain

One clue pointing specifically to December 25 comes from the story of Mary’s cousin Elizabeth, who approached old age without having given birth to any children. One day, her husband, a priest named Zacharias, was burning incense in the temple when the angel Gabriel appeared to him with good news: Elizabeth would bear a son. Early Christians guessed that Zacharias was probably in the temple for Yom Kippur, which they believed always took place on September 24 (it actually shifts year to year based on the Jewish lunisolar calendar). Nine months after September 24 is June 24, so they chose that as the birthdate—and feast day—of Elizabeth and Zacharias’s son, John the Baptist. When Gabriel later visited Mary to let her know that she’d bear a son, too, he mentioned that Elizabeth was in her sixth month of pregnancy. That means Jesus would’ve been conceived in late March, and born in late December—the night of December 24, to be exact, or the early hours of December 25.

Another theory suggests that Christians arrived at December 25 based on an ancient Jewish idea that prophets die on their birthday. During the 3rd century CE, theologists like Tertullian and Hippolytus dated Jesus’s crucifixion to March 25, since it happened around Passover. But to Sextus Julius Africanus, it was less about when Jesus was born and more about when he first came to Earth; in other words, he believed Jesus’s death and conception coincided on March 25, and thus his birth occurred on December 25 [PDF].

The Early History of Christmas

Even if Zacharias was in the temple on September 24, Gabriel did visit Mary exactly six months later, and Jesus was born right on his due date, it’s still possible that we celebrate Christmas on December 25 for a different reason altogether.

While 3rd-century Christians were busy worshiping the Son of God, some of their pagan counterparts were busy worshiping the Sun God. In the 270s, Roman emperor Aurelian popularized the cult of Sol Invictus, or “The Unconquered Sun,” whose feast day was celebrated on December 25. According to John Carroll University history professor Joseph F. Kelly, other Romans revered a Persian god, Mithra, whose feast day also may have fallen on December 25. There was also Saturnalia, an annual Roman festival that ran from December 17 to December 23. In short, many ancient Romans were well-accustomed to celebrating something in late December by the time Christianity entered the mainstream.

A painting of Saturnalia festivities by Antoine Callet, 1783.Themadchopper, Wikimedia Commons // Public Domain

That happened during Constantine’s rule over Rome in the early 4th century. In 313, Constantine and his fellow ruler Licinius issued the Edict of Milan, which basically legalized Christianity and condemned the ongoing persecution of anyone who practiced it. Constantine was a devout Christian himself, and he spent the rest of his reign spreading the religion throughout the empire. The first known record of December 25 as Jesus’s official birthday is from 336, the year before Constantine died. Because it’s mentioned in a volume containing other important religious dates, some have assumed that a celebration probably occurred on that day, and 336 is often cited as the first known “Christmas.”

Whether Christians celebrated Christmas on December 25 before 336 may forever be unknown, but we do know that the custom quickly caught on (spending the holiday watching A Christmas Story marathon wouldn't come until much later). By the end of the 4th century, Christian bishops were holding Christmas Mass all over Rome, and pagan festivals soon fell out of fashion. The fact that Christmas essentially replaced those earlier December traditions could be a coincidence, but some believe it was by design: Since Romans were already primed for parties on December 25, the Church could’ve been trying to co-opt a built-in subscriber base.

In summary, the origins of Christmas are just as subject to interpretation as Jesus’s actual birthdate—so feel free to play Christmas music whenever you want.

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