How (And Why) Do Cats Purr?

Cats purr for all kinds of reasons, including communication and healing themselves. Christian explains how purring works and which cats can't do it.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from how Stuff Works. Hey, I'm
Christian Sagar and this is brain stuff. Let's get something
straight about cats right away from the beginning. Not all
cats can purr. In fact, there's two kinds of cats,
the ones that purr and the ones that roar. For instance,

(00:24):
none of the panther knee I subfamily of cats can
pur This includes lions, leopards, jaguars, and tigers, but boy
can they roar. The cats that can purr include our
common domestic cats, as well as big cats that can't roar,
like bob cats, cheetahs, lynxes, pumas, and wildcats. These are
the ones we care about, right because it feels like

(00:46):
they're sharing their contentment with us when they're happy, and
we're just playing fascinated with cats because well, you know
the Internet. But how did these non roaring cats actually
do the whole purring thing anyway? Well, the most accepted
idea is that a cat's brain signals the laryngeal muscles
in its voice box, so they vibrate. These muscles act

(01:08):
like a valve by opening and closing the glottis that's
the space between the vocal cords, and then allowing air
to flow past the cat's voice box. One reason we're
pretty sure this is how purring works is that cats
with laryngeal paralysis can't purr. What makes purring so distinctive
is that it works when cats are both inhaling and exhaling.

(01:29):
This is why it seems like they can just keep
purring forever. And while we have a pretty good idea
how purring works in the throat, scientists don't exactly a
dent agree on how cats initiate purring. Some believe it's
a voluntary act, initiated by their nervous system. This would
mean that cats only purr when they want to, but

(01:49):
other studies suggest that the pur signal comes from a
neural oscillator in the cat's brain. Still, another theory is
that purring is caused by the release of endorphins. When
cats experien it's either pleasure or pain. That's right. Cats
don't always purr when they're happy. Sure, we mostly hear
them do it when we're petting or feeding them and nursing.
Kittens pur to let their mothers know their well because

(02:12):
they can't me out and drink milk at the same time.
So purring is kind of a way for them to
bond with their mothers and say hey mommy, I'm I'm okay.
But purring communicates more than just happiness. Upset, injured, sick,
and even dying cats are known to purr. Female cats
sometimes per when they're delivering kittens. Animal behaviorists think that

(02:32):
these cats are purring under difficult circumstances because they're comforting themselves.
It's also possible that frightened cats per to communicate peaceful
intentions to signal that they won't attack. Older cats do
this sometimes when they approach younger cats to say hey you,
I'm friendly. There's another pretty awesome hypothesis about white cats purr.

(02:53):
The rapid opening and closing of their vocal cords creates
a sound somewhere between twenty and a hundred and fifty hurt.
These sound frequencies can both improve bone density and act
as a natural healing mechanism. There's evidence that shows purring
can repair bones, relieve pain, and even heal wounds. This
goes all the way back to an old veterinary legend

(03:16):
that if you place a disembodied cat in a room
with all of their body parts, they can reassemble their bones. Together.
So wait, if other cats can only roar and not
pur does that also mean they don't have these crazy
healing powers. Check out the brain stuff channel on YouTube,
and for more on this and thousands of other topics,

(03:38):
visit how stuff works dot com