Human language

Purr is a love language that no human can speak

On the not-so-rare nights when I’m plagued by insomnia, no combination of melatonin, weighted blankets, and white noise will do. There is only one remedy for my illness: my cat Calvin, lying on my shoulder, puts me to sleep purring.

For veteran members of Club Purr, the reasons are clear. A purr is hot tea, a crackling fire and freshly baked cookies, all wrapped in a fleece-lined embrace; it is the auditory balm of a talkative stream; it’s the coffee that brews at dawn. It’s emotional gratification embodied – a sign that “we made our pets happy”, which just makes it seem damn goodexplains Wailani Sung, veterinary behaviorist at the San Francisco SPCA.

But purrs, one of the most recognizable sounds in the animal kingdom, are also one of the most mysterious. “Nobody, yet, knows how purring actually happens,” says Robert Eklund, a phonetician and linguist at Linköping University in Sweden. Experts also can’t say exactly what’s purring means. Cats purr when they are happy, but also sometimes when they are anxious or frightened, when they are in labor, or even when they are about to die. Cats are perhaps the most inscrutable creatures humans welcome into our homes, and purring is perhaps the most inscrutable sound they make.

There is at least some consensus on what is purring. In the strictest sense, the sound is a rhythmic, growling percolation that occurs during both exhalations – as is the case with most typical animal vocalizations – and inspirations, with no break in between. Purrs also spin their motors with their mouths fully closed, like little ventriloquist felines; sound simply springs from the body at a frequency that approximately covers the range between 20 and 150 Hertz. In the 1960s, a scientist postulated that purring was the product of blood percolating through the vena cava, a vessel that returns blood from the body to the heart; this notion was later refuted. Now it is generally understood that the source is the voicemail: The brain sends electrical signals to the vocal cords, prompting them to open and close like small, muscular doors.

Many animals can imitate the sound of purring, among them bears and guinea pigs. But only a handful of creatures can concoct an authentic version of the buzz: in addition to domestic cats, genets – look-alikes of small cats native to Africa – can; the same goes for the lynx, ocelots and dozens of other smaller members of the Felidae family. Eklund told me how a captive cheetah, named Caine, emits loud purrs from “the second he woke up to the second he fell asleep,” he told me. But lions, tigers and jaguars cannot elicit the same rattles; scientists have not documented any cats that can both purr and roar. Scientists can’t say for sure what separates purrs from purrs. It may have something to do with the length, shape, or thickness of some species’ voice box, or the tissue architecture that surrounds it; or maybe it’s the spongy bone of their hyoid, a U-shaped bone hanging in the throat. Or maybe not. Purring is not easy to study: felines generally do not like to produce sound around researchers in laboratories.

Whatever its mechanical basis, purring seems hard-wired in some cats from birth. They begin to spin their small musculoskeletal motors a few days after leaving the womb, while they are still blind and deaf. Kittens and mothers seem to exchange sounds as a form of early communication, exchanging essential messages such as I’m hungry and Hey, here comes momsays Hazel Carney, a feline veterinarian and purring expert based in Idaho, where she also cares for her three cats: Wyatt Earp, Calamity Jane and Hi Ho Silver. These early positive associations could partly explain why purring persists into adulthood, reappearing whenever cats simply curl up with their favorite humans, for example, or munch on a particularly tasty snack. Zazie Todd, animal behavior expert and author of the book Purr: the science to make your cat happy, told me that one of her cats, Harley, sometimes growls the moment Todd walks into a room, which is “really adorable.” For other felines, Sung told me, just eye contact with a beloved human can be enough to get that engine started.

But the gears of the purr can also turn in much less encouraging circumstances. Mikel Delgado, a feline behavior expert in California, told me she once had a purring cat at the vet. Sung even heard the noise when inserting a catheter into a patient. Scientists can only speculate what is going on. Carney told me that in some animals purring could be a sort of vocal tic, like nervous laughter; cats can also try to send calls for help or warning messages to anyone who dares approach. Or maybe the purrs of bad times are self-soothing, says Jill Caviness, a veterinarian and cat specialist at the University of Wisconsin at Madison, and parent of a feline named Electron. They could even be a cat’s attempt to trick its aching body into a less stressed state.

At the very beginning, a researcher offers that purring could even have palliative properties for cats, by emitting vibrational frequencies that could, for example, accelerate the healing of wounds or fractures. The thinking isn’t totally crazy, Eklund told me. Vibration therapy has shown some promise in animals like rabbits; same NASA once sued him, in hopes of avoiding or even reversing bone loss in astronauts heading for long stays in space. Carney has had plenty of clients who “swear that cats lying in their beds, purring next to them while they were sick, kept them from dying,” she told me. But alas: although cats can purr at frequencies that overlap with those used in vibration therapy, none of the research into these treatments has actually involved felines. “I don’t think we have studies that look like, I sat with a purring cat on my broken leg for 15 minutes a day; I healed faster than anyone else,” Caviness told me; the same goes for the effects of purring on purring. Carney is more open to the idea of ​​healing, although she also admits: if people feel better around their cats, it might be less due to the direct mechanical effects of purring on human tissue, and more to the fact that the pet is a psychological balm.

While communication with cats is currently experiencing a research boom, Eklund told me — new articles on the topic appear “basically every week” — purring may be less confusing than it ever was. summer. But among its cat-vocalizing cousins, its growls can still be unusually difficult to analyze, not least because in all contexts the purrs sound so similar. Meows can also be a bit enigmatic, but they have a more perceptible logic: it is not so difficult to analyze the Feed me; I’m legitimately starving meow sound Why am I in this cat carrier? to yell. Carney, who has spent years listening to purrs of all kinds, told me that such differences can also exist with purrs: satisfied rumbles tend to be more melodic and lower, while anxious rumbles tend to be higher and harder. And a study, from a few years ago, suggested that humans could distinguish their pet’s “prompting” purrs – a high-pitched, urgent sound cats make when looking for a meal – from other purrs they broadcast regularly. But such differences are very difficult to spot, especially in unfamiliar cats; even Caviness vet students can’t tell them apart at the clinic, she said.

And unlike many other cat noises, purrs stubbornly evade human imitation (although some people on YouTube may differ). Humans can easily meow at their cats; “It’s like a very rudimentary pidgin language,” Eklund said. But purr? Our brains and throats are simply not configured for this sort of thing. Which, for me, is a sweet tragedy: the growls of my two cats, Calvin and Hobbes, are missives of love, of joy, of happiness; they are tactile and auditory feedback to my touch. They are a token of affection that I can receive, but cannot return.

Some devices and soundtracks may offer substitutes. Some vet clinics play cat music in exam rooms, complete with a soothing purring bass track; Delgado mentioned that a shelter she worked at bought replacement nursing machines for orphaned kittens, which could be fitted with a synthetic purr. Purr lovers can even podcast an orange cat from Ireland named Bilbo purr for 30 minutes straight.

Purring is a language barrier that we have yet to overcome. Which, in some ways, is so, so cat. Humans have spent generations breeding dogs to emote in a very people way, using their soulful eyes and drooling, smiling mouths. Cats, however, continue to thrive on subtlety; their cups are not scalably configured for obvious expressions, defaulting to “resting cat face” instead. Even compared to other cat vocalizations, purring is subtle and intimate, a form of communication that relies on closeness, closeness, understanding a cat’s wants and needs – and maybe, sometimes , on his understanding of ours.

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