Cats and purring.

No doubt this question has been asked before, but the Straight Dope Message Board search never seems to work for me. I tried to Google Search these message boards on the topic, but with no success.

I’ve read and heard a lot about what it really means when your cat is purring. Everyone seems to have a different answer. There’s also the question of how cats purr.

Cecil says:

“Cats don’t purr just when they’re feeling chipper — they also purr when they’re frightened or badly hurt. Purring doesn’t have any specific emotional connotation; rather it seems to be a kind of homing device. Cats learn the signal in the first few days of kittenhood, when they can’t see, hear, or smell very well. The mother cat purrs to call the kittens to nurse — unable to hear the sound, the kitten can feel the vibrations.
There are two schools of thought on exactly how a cat purrs. One theory traces the vibrations to a set of “false vocal cords,” a bundle of membranes that lies above the genuine vocal chords and seems to have no other clear function. The other opinion locates the purr in the vibrations of the hyoid apparatus, a series of small bones connecting the skull and the larynx that nominally serves to support the tongue. Since it’s difficult to induce a cat to purr while you’re examining his hyoid apparatus, the truth may never be known.”

This was written in 1976.

I’ve heard that cat’s don’t purr when they are happy, period. I’ve heard that cat’s purr to get attention. I’ve heard that cat’s purr to tell you that they’re in a fragile state.

My parents have two cats, who I love dearly. It’s extremely hard for me to believe that a cat doesn’t purr out of affection. I know they have other reasons to “hum”, like Cecil mentioned, (when frightened or badly hurt), but it seems to me that cat’s generally do purr when they are happy or feeling “lovable”. Am I misreading what my parent’s cats are trying to tell me?

Also, do we still not know HOW a cat purrs? Seems like something we would have learned by now.

I wish I knew what cats were thinking. Do they feel love? Do they get depressed? Are they happy? Are they sad?

And to add to this question: What evolutionary purpose does purring serve? I assume all felines purr.

Check out

  • I assume all felines purr.*

Nope. The “roaring” cats don’t purr and purring cats don’t roar. Lions, tigers, jaguars and leopards roar.

Most big cats (lions and tigers and such) do not purr. Cheetahs do (there are plenty of youtube videos you can look up).

Evolutionarily speaking I don’t think that purring has to serve any purpose, so long as it isn’t a detriment to survival and reproduction. Obviously plenty of species get by just fine without purring so it’s not a necessity (or evidently even a big advantage).

Purring is also a learned behavior. If you have a very young rescue in a house with no cats, it will not learn to purr as a kitten. Although, if you later put that not-purring cat in a new house with purring cats, it will pick it up and start purring, so it can’t be a hard thing to do physically.

There’s no actual proof yet but the theory has been put forward that purring is a self-soothing behavior (like humans biting their lips or chewing on their hair/fingernails/pencils) that cats employ to de-stress themselves.

If that’s the case, then I would argue that it is evolutionarily important. A cat with fewer stress hormones cluttering up its system is a healthier cat, and a cat that can recover from stress faster and more reliably is a cat that is more likely to survive in a harsh environment.

If it helps (deaf and blind) kittens find their mothers then there’s your evolutionary advantage, but as Valgard says there doesn’t have to be an evolutionary advantage to purring, as long as there is no evolutionary disadvantage to it.

This is slightly controversial and depends on your definition of purring. By one definition the four roaring cats ( tiger, lion, leopard, jaguar - those with a two-piece hyoid bone ) can, but only on exhale. But another, which specifically defines a purr as being on both the inhale and exhale, excludes them by definition. Balderdash say the first group. And the debate rages on.

But that first video works for me - roaring cats are one-way purrers ;).

I’m surprised no one’s brought this up yet. Cats purr when injured to help themselves heal. Low frequency vibration helps speed the healing of wounds and broken bones. As Cecil noted, cats purr when injured, although he didn’t say why. I believe the healing powers of purring were discovered some time after the column was written. Speeding up healing would certainly be an evolutionary advantage.

I’ve also had a theory that cats help people to live longer because a purring cat sitting on your lap or snuggled beside your stomach will help you digest your food.

I have no idea if that’s true.

I recently read about a study that said purring helps lower blood pressure – both of the purring cat and of the human petting said cat.

I read that study too, and cats have a calming effect on humans, more so than dogs.

About purring – both my cats (mom cat is 13 and her kitten is 11) purr when they want food, and purr right up to when I put their food out for them at mealtimes. Mom cat jumps on my lap purring when I eat yogurt and purrs all the way through sharing it with me. Both like to sit behind my head when I watch TV and purr when I look at them or pet them.

But her kitten does one better. She has a way of talking while she purrs. Kind of a meowpurr or purrmeow. It is especially strong right before she is fed.

My father let my cat into the house one night. I had just gotten into bed, and he crawled onto my chest in his normal sleep position. But his purr was so loud that it was unnerving. So I turned on the light and discovered one of his eyes danging out of its socket. He’d gotten into a bad fight with a dog, we suspect.

Yikes Monstro.

So with cats, could we have played a role in the evolutionary trait being passed down? Since there MAY be evidence for mutual benefits, if it lowers their heart rates?

Unlikely in the extreme. Only one species of cat is domesticated, yet they all purr or at least many of them do. So purring almost certainly evolved before all these purring species differentiated themselves. It must be something that evolved in the primordial cat.

Yes, the frequency of purring increases bone density. That may not be the reason cats do it (or may be one of myriad side effects), but it is a possible effect.

I think when our cat purrs that means she’s planning how she’s going to murder me. And when she’s not purring, that means she’s planning on how she’s going to murder me.


Our big cat Archie, a tomcat without peer (other people called him a “bully” on the block). would jump onto the couch next to my Mom; he would curl up quietly, and purr loudly. He had a very strong bond with all of us. :slight_smile: