(classical music)
- Hi, I'm Cristen from Stuff Mom Never Told You,
and let's get something straight about cats
right from the beginning.
Not all cats purr.
In fact, there are two kinds of cats,
the ones that purr
(cat purrs)
and the ones that roar.
(lion roars)
For instance, none of the Pantherinae subfamily
of cats can purr.
And this includes lions, leopards, jaguars and tigers.
But boy, can they roar.
Now the cats that can purr include our domestic common cats
as well as big cats that can't roar,
like bobcats, cheetahs, lynxes, pumas and wildcats.
And these are the ones we care about, right?
Because it feels like they're sharing their contentment
with us when they're happy.
And we are just plain fascinated with cats
because I mean, you know, the internet.
But how do these non-roaring cats
actually do the whole purring thing anyway?
Well, the most accepted idea is that a cat's brain signals
its laryngeal muscles in its voice box so that they vibrate.
These muscles then act like a valve
by opening and closing the glottis
which is the space between vocal cords.
And that allows air to flow past the cat's voice box.
Now one reason we're pretty sure
this is how purring works
is that cats with laryngeal paralysis can't purr.
So what makes purring so distinctive,
is that it works when cats are both inhaling and exhaling.
And this is why it seems
that they can just keep purring forever.
And while we have a pretty good idea
of how purring works in the throat,
scientists don't 100% agree
on how cats initiate purring.
Some believe that it's a voluntary act initiated
by their nervous system.
So this would mean that cats only purr when they want to.
Sounds very much like cats.
But other studies suggest that the purr signal comes
from a neural oscillator in the cat's brain.
And then still another theory is that purring is caused
by the release of endorphins
when cats experience 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 them or feeding them.
And nursing kittens purr
to let their mothers know they're well
because they can't meow and drink milk at the same time.
So purring is a way to bond with their mothers
and say hey cat mom, I'm A-okay.
But purring communicates more than just happiness.
Upset, injured, sick or even dying cats are known to purr.
And female cats sometimes purr
when they're delivering kittens.
Animal behaviorists think that these cats are purring
under difficult circumstances
because they're comforting themselves.
Now it's also possible that frightened cats purr
to communicate peaceful intentions,
to signal that they are not going to attack.
And so older cats do this sometimes
when they approach younger cats
to say hey, younger cat, I am totally friendly.
Please don't scratch my face off.
Now there's another pretty awesome hypothesis
about why cats purr.
The rapid opening and closing of their vocal chords creates
a sound between 25 and 150 hertz.
And these sound frequencies can both improve bone density
and act as a natural healing mechanism.
There is evidence, in fact, that shows
that purring can repair bones, relieve pain and heal wounds.
And this goes all the way back to an old veterinary legend
that if you place a disembodied cat in a room
with all of its body parts,
they can reassemble their bones together.
Yeah, like Frankencats.
So wait, if other cats can only roar and not purr,
does that also mean
that they don't have these crazy healing powers?
What do you think?
Let us know in the comments below,
and don't forget to subscribe to Brain Stuff.