On Monday morning, my partner laid a carry-on suitcase down on the floor, preparing to pack for his first post-vaccination trip to visit his parents. The moment he unzipped the bag, our cat Calvin promptly clambered inside.
A piece of me would like to think that Calvin was attempting to covertly join my partner on his trip, or perhaps thwart his inevitable attempt to spirit away. But I’m pretty sure #OccupyLuggage was less a heart-wrenching bid to tag along on a flight, and more a textbook example of a central scientific tenet: Cats are absolute suckers for boxes. And sinks, and vases, and grocery bags, and shoes, and Pringles cans, and the nooks and crannies between furniture and walls, and just about any other space they deem cozy, confining, and swaddly. (Cats, in case you were wondering, are a non-Newtonian liquid.) It’s the one thing about which our pointy-eared companions are not terribly picky: If it fits, they sits. And when they do, we humans can’t help but obsess over them.
Across the internet, felines’ beguiling fluidity and vaguely psychopathic tendencies spark a mixture of adulation and fear. Internet cats vibe, LOL, lust after cheeseburgers, and vaguely resemble the Führer. But it’s perhaps cat booty, and the spaces it parks itself in, that commands one of the most interesting and best publicized cultural memes of all. In April 2017, the phenomenon of cats moseying into boxes took over Twitter with the hashtag #CatSquare. And last week, a new study plumbing the depths of the cat-box phenomenon went viral, spawning thousands of likes and a stream of cat-stanning coverage. “I can’t believe how much attention this is getting,” Gabriella Smith, a behavioral biologist who led the study at Hunter College, told me. The allure of the boxed cat is perhaps a kind of entrapment in its own right—time out of our days, space taken up in our brains, while the felines are none the wiser. Humans have cohabited with cats for thousands of years. But we still can’t tell exactly who is domesticating whom.
For all the hype that box-cats command, scientists still don’t fully understand why felines both big and small so fervidly flop their keisters into anything and everything. And because cats are generally uncooperative study subjects, humans have had a hell of a time trying to suss it all out. “We can’t get into those little brains,” Mikel Delgado, a cat-behavior expert at Feline Minds, a cat-behavior consulting group, told me.
But at least a handful of theories have been tossed around. One posits that cats squish themselves into small spaces in search of solace. The world is a legitimately terrifying place, and grocery bags, drawers, and Amazon packages might be the best analogue to a cave that a house cat can find. “To a cat who’s nervous, a box represents shelter and safety,” Delgado said. Certain containers might also provide an insulating effect—a sort of crude cardboard hug. Some animal behaviorists think that being squeezed by enclosures might even remind cats of being snuggled by their mothers and littermates. Whatever the exact source of the comfort, having a hidey hole to retreat into seems to embolden cats: One 2014 study found that shelter cats who were gifted boxes in their new home were less stressed than their boxless housemates, and adjusted to their surroundings faster.
Another idea holds that cats aren’t retreating into receptacles, but strategizing from them like the ruthless assassins they are. “A box provides cover for a predator,” Delgado told me. Enclosed spaces, it turns out, are excellent vantage points from which to stalk and ambush prey, be it a mouse, a feathery wand toy, or a hapless human foot.
But none of these explanations can really account for why the mere shape of a box is so beguiling to some cats, who have been documented planting their butts down on mouse pads, letters, place mats, baking sheets, even rectangles demarcated by tape. Calvin is one of the weirdos for whom wall-lessness is no barrier: He will commandeer any vaguely polygonal object in sight. “It’s truly mystifying,” says Gita Gnanadesikan, an animal-behavior researcher at the University of Arizona who fosters undersocialized cats. “They have the whole floor to choose from, and they sit on a sheet of paper.”
It’s possible that cats are just extending their impulse from high-sided containers to shallow ones. They might even be gambling on the off chance that something that appears to be flat is deceptively deep, Delgado told me: “I’m going to err on the side of, It’s a box.” But another big driver, she said, is almost certainly the classic cat Achilles’ heel: curiosity. The appearance of an unfamiliar object is a surefire way to pique a cat’s interest, perhaps even enough for your pet to try to ensconce themselves in it.
Even a box without any true borders seems enough to trip cats’ shape-seeking senses. Smith tested this notion in her new study using the Kanizsa-square illusion—a visual trick in which strategically placed Pac-Man shapes evoke the perception of a square that’s not actually there. A small number of lab-trained cats had been documented falling for the illusion before, but Smith and her colleagues were keen on finding out whether pet felines would instinctively spring for the faux squares. Just 30 cats saw the experiment through to the end, most of whom expressed no interest in any floor shapes at all, illusory or not. But the felines who did were about as likely to sit on a Kanizsa square as a definitively outlined one. It’s a small group of cats, Gnanadesikan told me, but the trend the team observed isn’t terribly surprising, given that researchers already knew that cats covet flattened shapes with obvious perimeters. “This is just one more step in that direction,” she said.
The last variable in the cat-box equation is, well, us. We’re the agents of chaos who built our environments to be amenable to cats. Cats sit in boxes because we provide them. Their videos go viral because we film them and share them. Some cats, left to their own devices, might not go gaga for boxes at all, if not for the fact that the humans they love lavish attention on them when they oblige. Perhaps we so desperately and doggedly document cats because we’re finally trying to tame them for good. But in the end, it’s almost always we humans who end up boxed in.
Something about the box behavior is almost certainly ancient and ingrained, written deep into the DNA that cats and humans share. A year into the pandemic, people can certainly relate to a craving for security and a desire to define our own boundaries, made up though they might sometimes be. But Delgado, who has made a career out of assessing cat behavior, says there’s merit to giving in to the mystery. Cats are, above all else, inscrutable creatures. In a particularly cheesy demonstration of the box phenomenon, one of Delgado’s own pet felines once plopped his tush into a pan of lasagna. (Warm? Check. Secure? No. Stealthy? Depends on where he was headed next.)
On Monday, after Calvin relinquished the suitcase, I tried a version of Smith’s Kanizsa experiment on him by cutting out four Pac-Man shapes and arranging them to hint at a square. Calvin strode confidently over to the configuration and parked his booty not inside the square, but onto one of the illusory cutouts. It was a moment enshrined in tragedy: He could not squeeze the entirety of his substantial rump into a three-quarter circle. In the end, he had fallen prey to the greatest deception of them all—the true size of his own bum.