Speaker 1: Welcome to brain Stuff from how Stuff Works. Hey, I'm
Speaker 1: Christian Sagar and this is brain stuff. Let's get something
Speaker 1: straight about cats right away from the beginning. Not all
Speaker 1: cats can purr. In fact, there's two kinds of cats,
Speaker 1: the ones that purr and the ones that roar. For instance,
Speaker 1: none of the panther knee I subfamily of cats can
Speaker 1: pur This includes lions, leopards, jaguars, and tigers, but boy
Speaker 1: can they roar. The cats that can purr include our
Speaker 1: common domestic cats, as well as big cats that can't roar,
Speaker 1: like bob cats, cheetahs, lynxes, pumas, and wildcats. These are
Speaker 1: the ones we care about, right because it feels like
Speaker 1: they're sharing their contentment with us when they're happy, and
Speaker 1: we're just playing fascinated with cats because well, you know
Speaker 1: the Internet. But how did these non roaring cats actually
Speaker 1: do the whole purring thing anyway? Well, the most accepted
Speaker 1: idea is that a cat's brain signals the laryngeal muscles
Speaker 1: in its voice box, so they vibrate. These muscles act
Speaker 1: like a valve by opening and closing the glottis that's
Speaker 1: the space between the vocal cords, and then allowing air
Speaker 1: to flow past the cat's voice box. One reason we're
Speaker 1: pretty sure this is how purring works is that cats
Speaker 1: with laryngeal paralysis can't purr. What makes purring so distinctive
Speaker 1: is that it works when cats are both inhaling and exhaling.
Speaker 1: This is why it seems like they can just keep
Speaker 1: purring forever. And while we have a pretty good idea
Speaker 1: how purring works in the throat, scientists don't exactly a
Speaker 1: dent agree on how cats initiate purring. Some believe it's
Speaker 1: a voluntary act, initiated by their nervous system. This would
Speaker 1: mean that cats only purr when they want to, but
Speaker 1: other studies suggest that the pur signal comes from a
Speaker 1: neural oscillator in the cat's brain. Still, another theory is
Speaker 1: that purring is caused by the release of endorphins. When
Speaker 1: cats experien it's either pleasure or pain. That's right. Cats
Speaker 1: don't always purr when they're happy. Sure, we mostly hear
Speaker 1: them do it when we're petting or feeding them and nursing.
Speaker 1: Kittens pur to let their mothers know their well because
Speaker 1: they can't me out and drink milk at the same time.
Speaker 1: So purring is kind of a way for them to
Speaker 1: bond with their mothers and say hey mommy, I'm I'm okay.
Speaker 1: But purring communicates more than just happiness. Upset, injured, sick,
Speaker 1: and even dying cats are known to purr. Female cats
Speaker 1: sometimes per when they're delivering kittens. Animal behaviorists think that
Speaker 1: these cats are purring under difficult circumstances because they're comforting themselves.
Speaker 1: It's also possible that frightened cats per to communicate peaceful
Speaker 1: intentions to signal that they won't attack. Older cats do
Speaker 1: this sometimes when they approach younger cats to say hey you,
Speaker 1: I'm friendly. There's another pretty awesome hypothesis about white cats purr.
Speaker 1: The rapid opening and closing of their vocal cords creates
Speaker 1: a sound somewhere between twenty and a hundred and fifty hurt.
Speaker 1: These sound frequencies can both improve bone density and act
Speaker 1: as a natural healing mechanism. There's evidence that shows purring
Speaker 1: can repair bones, relieve pain, and even heal wounds. This
Speaker 1: goes all the way back to an old veterinary legend
Speaker 1: that if you place a disembodied cat in a room
Speaker 1: with all of their body parts, they can reassemble their bones. Together.
Speaker 1: So wait, if other cats can only roar and not
Speaker 1: pur does that also mean they don't have these crazy
Speaker 1: healing powers. Check out the brain stuff channel on YouTube,
Speaker 1: and for more on this and thousands of other topics,
Speaker 1: visit how stuff works dot com