Why do cats purr?
Communication! That's the answer!
One of the best aspects of cat-ownership is knowing that your cat has more than one way to communicate. Meowing is the most frequent and direct. It is very hard to ignore the vocalizing of your cat, which practically seems designed specifically to cut through any human state of concentration. Well-trained owners claim they can tell the difference among 'food,' 'out,' and 'I'm bored' meows from as far away as the cozy bed they are just about to abandon, in summons to a genuine 'cat-call.' So, with a few cat supplies and a well-trained ear, most cat-owners have no problem keeping their furry friend happy.
Assuming they have responded correctly, owners can claim their reward from another cat-communication system, purring. Even hauled out of bed in a fog of resentment, owners melt at the sound of purring. The rhythmic vibration of diaphragm and larynx somehow sounds both grateful and approving. Why do cats purr? Obedient owners, crawling back under the covers, will assure you that it's part of the owner-training program every cat seems to conduct, and that it's very effective acknowledgment of good human behavior.
The Science of Purring
Scientists and experienced owners suggest that purring performs several other functions for cats. As an expression of pleasure and security, purring most likely begins at nursing in kittenhood. Both mothers and kittens often purr during nursing. In houses with more than one cat, purring may perform another social function, that being demonstration by one cat of subservience to another. Purring shows one cat means no harm and poses no threat to the other.
That kind of purring, however, may merely signal the stress felt by a cat in fear of attack. Cats have been observed to purr when badly hurt or ill. Scientists speculate that the frequency at which cats purr (usually between 25 and 150 Hertz) may perform a healing function. Exposure to such frequencies can promote strengthening and healing in human bones. Because cats have the reputation of being able to recover astonishingly from near-fatal injuries, one hypothesis is that purring signals a cat's activation of healing soundwaves rather like the use of ultrasound. Milder episodes of steady purring on a visit to the vet, when lost, in a carrier, or in the presence of a strange animal signal some kind of stress-release or self-comfort in fear-provoking situations. Just as some humans are able to reduce stress by meditation or visualization, it is possible that cats reduce stress by purring.
Regulating Your Cat's Purrs
Several questions recur when examining why cats purr. Is purring something a cat can regulate voluntarily? Observers differ on whether purring is a voluntary or involuntary function of a cat's nervous system. Do cats purr when they are alone? Owners differ, depending on their experiences.
Some insist that their cats purr while sleeping; others report that purring shifts into snoring in a sleeping cat. Hard data on this subject tends to be filed with information gathered on the sound of one hand clapping.
The Benefits of Purring
As a social device, however, a cat-to-human communication system like purring has several beneficial effects. First it signals to owners that they are on the right track: rubbing behind that ear brings pleasure, as will continuing behind the other. Sudden silence from a purring lap-cat commands immediate attention and redirects the patting hand more effective than a shout. Recent studies suggest a positive relationship between stroking an animal and decreases in human feelings of stress and human blood-pressure.
Even looking at animals can have a quieting, de-stressing effect. While their general independence makes them mildly less manageable than dogs, cats are increasingly joining the ranks of therapy animals, offering soothing companionship to ill elderly and mentally- or developmentally-disabled people. One wonders whether a purring cat was the prototype for vibrating and heat-generating massage pillows. Occasionally, pet lovers will locate an inn or bed-and-breakfast guesthouse offering a choice of cats for one's bed at night.
Most often, though, the question, why do cats purr, becomes quickly subordinated to the sheer pleasure in their doing so. The ability to produce such a warm, friendly sound from an animal by simple tasks raises feelings of pleasure and pride in children and adults alike. No matter what has happened during the rest of the day, a cat's purr signals rest and contentment. A meow may say 'Food!' 'Out!' 'Play!' Purring simply says, 'It's okay—relax—it's okay.'