Cats Don’t Just Purr When They’re Happy

“In ancient times cats were worshiped as gods; they have not forgotten this.” —Terry Pratchett

In A Nutshell

Most people associate a purring cat with one comfortably curled up on the lap of someone who’s petting her. But cats will also purr when they’re scared or in pain, bringing up the question of why the same sound is made in such opposite circumstances. The answer might lie in the frequency of the cat’s purr, and the comforting, healing ability associated with it. The frequency of a cat’s purr is the same frequency that heals broken bones and muscles, making it likely that cats have an ulterior motive in their purring, too.

The Whole Bushel

Cats can purr because they have amazing control over the muscles in their larynx. When their laryngeal muscles twitch, this pulls their very stiff vocal cords apart and causes the sound of purring as they breathe in and out. Most of us are familiar with the happy, content cat purring away on someone’s lap, but cats also purr when they’re scared, upset, or injured. Cats will often purr when they’re in a stressful situation like waiting in the vet’s office, or when confronted with a scary new creature.

So why do they make the same sound in completely opposite situations?

While no cats are telling, scientists have made some educated guesses—and it starts with what’s hidden inside the sound of a cat’s purr.

Since the purr is generated by the cat’s breathing, it’s a sound with a regular rhythm. It also has a frequency that’s somewhere between 25 and 150 Hertz. Scientists don’t think that’s a coincidence.

That’s the same frequency that has been found to encourage healing in bones and muscles, and it might explain why injured cats purr—they’re helping their own body to heal. And as an added bonus, since the purring sound is generated by their own breath, it’s a very low-energy form of therapy. And oddly enough, it’s not just beneficial for the cat. The University of Minnesota Stroke Center has found that people who own a cat or two are as much as 40 percent less likely to have a stroke; it’s thought that the calming effects of having a cat around, coupled with the healing properties of the purr, might have something to do with that.

Not all cats can purr; those that can roar can’t purr (due to the different structure of their vocal cords). But a variety of cats can purr, not just your domestic housecat. Cheetahs, ocelots, and other “small” big cats can also purr, and recordings of their sounds have shown that they have the same frequency. This gives credence to the theory that they’re not just purring for you.

So why do they purr when they’re happy?

This is where they turn into the manipulative little creatures they have a reputation for being. Researchers at the University of Sussex have gone a bit farther in examining just what the sound of a purr is, and they’ve found something surprising. Inside the 25–150 Hertz range of the purr is another sound—namely, a hidden cry that registers between 220 and 520 Hertz.

As a comparison, that’s a frequency very similar to the cries of a human baby.

Purring is an important part of cat communication from the time they’re kittens, purring at their mother for attention. And they might be doing the same to you, hiding a rather annoying plea for attention and more petting deep inside the sound of their more pleasant, calming, and therapeutic purr. It makes them extremely hard to ignore, and pretty much guarantees that you’ll keep doing whatever you’re doing to make them happy.

Some cats have been known to purr when they want to be fed as well. This secret purr might be the reason they’re so hard to ignore when they wake you up in the morning for their breakfast.

Show Me The Proof

Scientific American: Why do cats purr?
Mother Nature Network: Why do cats purr?

  • Mikey Godsey

    “…the same frequency that heals broken bones and muscles”.

    That’s pseudo-scientific bullshit.

    • Lisa

      LOL you got down voted for stating the obvious. Is this knowledgenuts or psychicnuts? How did crazy nonsense get on this site? oh it’s associated with listverse…

      • Mikey Godsey

        Just because you know something isn’t a good source of credible information doesn’t mean something glaringly and ridiculously incorrect shouldn’t be pointed out for those that don’t know better. You got down-voted for being negative and cynical.

        • Lisa

          It was sarcasm. I actually voted it up and the nonsense I was referring to was the bone healing stuff.

    • [Not Another Lisa]

      Yes, I too look to Scientific American to back up my pseudo-scientific bullshit.

  • Lisa

    The author is obviously stupid. Can I heal my bones with happy thoughts too or press the snooze button with my mind?

    • Valkyrie

      It looks like your mind is already closed so no.

      • Lisa

        Are you one of the nutters that believes that crap?

        • Valkyrie

          Compared to you being an obnoxious troll I would take the side of the so called ‘nutters’ any day

          • shmabai

            Im not sure if that’s the real lisa. I’ve been reading some lists and it seems a troll has been using her name. All her real comments seem to be from a very nice person, this isn’t lol.

          • Lisa 39

            Thank you shmabai

          • Lisa

            Are you stupid enough to believe that there’s only one person on earth with the name Lisa?

          • Lisa

            Good luck with the happy thoughts next time you break something.

          • Valkyrie

            There’s not been a first time i’ve broken anything so there won’t be a next time either .. goodbye Troll

          • Lisa

            I can always hope.

          • Valkyrie

            If you spend your whole life hoping people hurt themselves then you are a very shallow pathetic arsehole, but then you already know that don’t you

          • Lisa

            Yeah, I spend my whole life wishing that a random stranger with a stupid cat picture will hurt themselves.

          • Valkyrie

            At least I use an avatar that shows a bit of personality, yours however just shows a big fat blob for a head..how apt

          • Lisa

            I don’t have a picture. I don’t have any idea what you’re looking at.

          • Nick Mulgrave

            Maybe a cats purr can encourage the healing of your personality? Give it a shot. It appears you have nothing to lose.

          • Lisa

            A cat’s purr does nothing. You’re going to make someone a great mark one day.

          • Nick Mulgrave

            Glad to see you gave it a go, but too bad you didn’t have any luck.
            Maybe its all of the barking that negates the healing power of the cats purr?
            Also thanks for the positive encouragement.
            Maybe one day you too will make something great as well.

          • Lisa

            That doesn’t make any sense.

      • Lisa 39

        Hi valkyrie, i read an article in a magazine maybe 4 or 5 years ago about a young man with brain cancer that was inoperable & no treatment would help, basically a death sentence. He was a christian so he prayed every day, not for a miracle just peace but when he went to bed every night he would picture the cancer cells as invaders from a video game and focus on shooting & destroying them all night even while dreaming. I don’t remember how long he did that but when he went back to the doc he was cancer free. So yes i believe the mind can do amazing things for people who are open minded. Now guess which lisa i am lol

        • Lisa

          The stupid one. Was it the national enquirer?

  • Hillyard

    In short cats can’t be trusted. You think they’re happy, but they’re just trying to get fed.

    • Lisa 39

      Right? I tell my 3 cats they’re going to end up in my cauldron all the time

  • Mezcal Turis

    Sci show on Astronauts. It tells that purrs can heal bone and muscle density. Look it up.

    • Lisa

      Do you believe in the tooth fairy too?