The language of love that only cats understand – Katherine J. Wu

On fairly frequent nights when I suffer from insomnia, no combination of melatonin, blankets and white noise can help me. There is only one cure for my pains: my cat Calvin, lying on his back, making me fall asleep with his purr.

For older members of the purring club, the reasons are obvious. The purr is hot tea, crackling fire and freshly baked cookies, all wrapped in a fleece-lined embrace; I am the sonorous balm of a bubbling stream, the preparation of coffee at dawn. It is emotional gratification embodied, a sign
that “we made our pets happy,” a damn good feeling, says Wailani Sung, a behavioral veterinarian at the Society for the Prevention of Cruelty to Animals (SPCA) in San Francisco.

But purring, one of the most recognizable sounds in the animal kingdom, is also one of the most mysterious. “Nobody knows how purring sounds yet,” says Robert Eklund, a phonetician and linguist at Linköping University in Sweden. Even experts don’t know exactly what they mean. Cats purr when they are happy, but sometimes also when they are anxious or afraid, when they are in labor, and even when they are about to die. Cats are perhaps the most inscrutable creatures humans welcome into their homes, and purring is the most inscrutable sound they make.

Little feline ventriloquists
There is some consensus on what purring is. Strictly speaking, it is a rhythmic and rumbling sound produced both during the exhalations, as occurs in most animal vocalizations, and during the inhalations, without interruptions between the two phases. The purrs are emitted even with the mouth completely closed, as if they were the result of small feline ventriloquists and the sound comes from the body at a frequency that extends between twenty and 150 hertz.

In the 1960s, a scientist hypothesized that purring was the product of blood flowing through the vena cava, a vessel that returns the body’s blood to the heart, but this idea was later disproved. Today, the source is believed to be the larynx: the brain sends electrical signals to the vocal cords, prompting them to open and close like small muscle doors.

Many animals can mimic the purring sound, for example bears and guinea pigs. But there are few animals capable of purring: in addition to domestic cats, genets, small doubles of cats originating in Africa, can do so. The same goes for bobcats, American ocelots and dozens of other members of the cat family. Eklund told me about a captive cheetah, named Caine, who purred rumbling “from the moment he woke up to the time he fell asleep.” But lions, tigers and jaguars can’t make the same sounds, and scientists have never documented any cats that can both purr and roar.

Scientists can’t say for sure what distinguishes those who purr from those who don’t. The difference could be related to the length, shape or thickness of the voice box of some species, or to the architecture of the surrounding tissues; or perhaps with the compactness of their hyoid, a u-shaped bone suspended in their throat. Or maybe not. Purring is not easy to study: felines usually
they tend not to make this sound when surrounded by researchers in laboratories.

Whatever the mechanical functioning, some cats purr from birth and start spinning their little engines within days of exiting the womb, when they are still blind and deaf. Kittens and mothers appear to be exchanging sounds as a form of early communication, throwing essential messages like “I’m hungry” and “Mom is coming,” says Hazel Carney, a veterinary and purring expert who lives in Idaho, where she cares. also of his three cats: Wyatt Earp, Calamity Jane and Hi Ho Silver. These early positive associations may be part of why purring persists into adulthood, reappearing whenever cats snuggle up to their favorite humans. Or when they eat particularly tasty food.

Zazie Todd, animal behavior expert and author of the book Purr: _the science of m__aking your cat happy_ (Purrr: the science of making your cat happy), told me that one of her cats, Harley, sometimes grunts the moment she walks into a room, which is ” really adorable ”. For other felines, Sung told me, mere eye contact with a loved human being may be enough to activate that engine.

Self-comfort
But purr gears can also kick in under much less cheerful circumstances. Mikel Delgado, a feline behavior expert in California, told me that she once had a cat purring at the vet. Sung even heard the noise as she inserted a catheter into a cat she was caring for. Scientists can only speculate on what happens in those cases. Carney told me that purring in some animals could be a kind of vocal tic, like a nervous laugh; cats might also try to send out requests for help or warning messages to anyone who dares to approach.

Or maybe purring in difficult times is a form of self-consolation, says Jill Caviness, a veterinarian and cat expert at the University of Wisconsin in Madison, as well as the owner of a feline named Electron. They could also be an attempt by the cat to trick their own body, which is afflicted with pain, and
bring him to a state of less stress.

In the early 1980s, a researcher had advanced the idea that purring could even have palliative properties for cats, emitting vibratory frequencies that could, for example, accelerate the healing of wounds or broken bones. “The idea is not entirely absurd,” Eklund told me. Vibration therapy has shown promise in animals such as rabbits. NASA has also pursued it, hoping to avoid, or even reverse, the loss of bone tissue in astronauts who spend long periods in space. Carney has had many clients who “swear that cats purring next to them while they were sick prevented them from dying,” he told me.

But unfortunately things aren’t that simple: Although cats can purr at frequencies similar to those used in vibration therapy, none of the research on these treatments has actually involved felines. “I don’t think there are any studies showing that if a purring cat sits on your lap for fifteen minutes a day when you’re sick, then it heals faster,” Caviness tells me. And the same goes for the effects of the purr on the emitter. Carney is more open to the idea of ​​healing, although she herself admits that people probably feel better around their cats not so much because of the effects of purring vibrations on human tissue, but because the pet is a pet. , in itself, a “psychological balm”.

Purr of all kinds
Cat communication is experiencing a real research boom – Eklund told me that new articles on the subject appear “practically every week” – and purring is perhaps less enigmatic than it is.
ever been. But among animals that reproduce the vocalizations of cats, these rumblings can still be unusually difficult to analyze, not least because, in different contexts, purrs sound very similar. Meows can be a bit cryptic too, but they have an easier logic to discern: it’s not
so hard to distinguish my Calvin’s meow when he says “feed me, I’m really starving” from his “why am I in this crate” complete with screams attached.

Carney, who has spent years listening to all sorts of purrs, told me these differences can exist: rumblings of joy tend to be more melodious and lower, while anxious ones tend to be higher and harder. A study from a few years ago suggested that humans were able to recognize their pets’ “solicitation” purring – an urgent, high-pitched sound that cats make when looking for food – from the usual purrs they made regularly. But differences like these are very difficult to recognize, especially in unfamiliar cats; even Caviness vet students can’t tell them apart in the clinic, she said.

Plus, unlike many other cat noises, purrs stubbornly escape human imitation (although some YouTube users may disagree). Humans can easily respond to their cats with a meow, “it’s like a tongue pidgin very rudimentary, ”says Eklund. But the purr? Our
brain and our throat are not predisposed to reproduce this sound. Which, for me, is a small tragedy: the rumblings of my two cats, Calvin and Hobbes, are messages of love, of joy, of bliss; they are tactile and auditory feedback to my touch. They are a sign of affection that I can receive but cannot return.

Some devices and soundtracks may offer substitutes. There are veterinary clinics that play cat music in the exam rooms, with a calming purr underneath. Delgado told me that a cattery he used to work in bought nursing machines for orphaned kittens, which are equipped with synthetic purrs. Purring enthusiasts can also listen to the podcast of an Irish orange cat named Bilbo, purring for thirty minutes straight.

Purring is a language barrier that we have not yet overcome. Which, in some ways, is very, very “catlike”. Humans have spent generations crossing dog breeds so that they best emulate people’s emotions, using their soulful eyes and slobbering, smiling mouths. Cats, on the other hand, continue to exploit their elusiveness: their snouts are not evolutionarily predisposed to emulate human expressions, and are always expressed with the typical “resting face”.

Even compared to other cat vocalizations, purring is subtle and intimate, a form of communication that is based on closeness, proximity, understanding the cat’s wants and needs. And perhaps, at times, about understanding ours.

(Translation by Federico Ferrone)