So Einstein finally finished that theory about space he's been working on.

It's about time, too. Right?

[laughter]

Any of you know how to throw a space party? I guess you just planet!

[laughter]

Celebrity gossip! Oxygen and magnesium are dating. O-Mg!

[laughter]

On the surface, laughter appears to be an unconscious, instantaneous reaction to something

that pleases us rather than displeases us,

but laughter is actually much more complicated than that,

and it has surprisingly little to do with the human sense of humor.

Now, I promise for the rest of this video, I'm only going to make science puns… periodically.

[MUSIC]

Laughter is one of those rare and beautiful things shared by people all over Earth,

a human experience that transcends borders of language, geography, and lifestyle.

No one has to teach us to laugh, and people everywhere do it pretty much the same way.

But it’s also really, really strange. [laughing]

Squeezing up your face and gnashing your teeth at other people while uncontrollably grunting

and hyperventilating, that’s a very weird thing to do. You’re weird. We’re all weird.

Laughing isn’t that different from breathing. We have incredibly fine muscle control over

how we let out breath, it’s what lets us make the intricate and detailed vocal noises

that we call speech.

But while we write out laughter with ha ha ha, it’s not really something we speak.

If I actually laughed like “HA HA HA” then laughter would be even weirder than it already is

and like I said, plenty weird.

Laughing is this sort of “heh heh heh” percussive air squeezing,

maybe the simplest vocal noise we can make.

If we think of talking like playing human bagpipes, constant pressure and intricate control,

then laughing like one of those silly little horns.

Think humans are the only animals that laugh? Not by a long shot. Primates do it,

dogs do a form of laughter, even rats do it. Yes, even rats.

The folks from Radiolab got it on tape.

[sound of rat "laughing"]

In animals, sometimes it’s associated with tickling, sometimes with play,

but laughing is almost always social.

Same goes for us. Humans laugh for a number of reasons, but most of the time it has nothing

to with funny business. Researchers like Robert Provine have found, after listening to hundreds

of people laugh in social situations, less than 1 in 5 chuckles are in response to humor,

and when a joke is involved, the person telling it is far more likely to be the one laughing.

We’re also 30 times more likely to laugh with other people around than if we’re are alone.

If laughter is a form of communication, then what are we trying to say?

We do it to communicate understanding, to show we like and accept others,

to diffuse awkward situations, and yes, sometimes even to be mean.

On January 30, 1962, at a boarding school in Tanzania, three young girls started giggling.

Their laughter spread throughout the school, uncontrollably, and ultimately 95 students

experienced laughing fits. One even laughed for 16 days straight.

As a result of this “omuneepo” the school was temporarily closed, but the laughing spread

to the girls home villages, eventually this side-splitting mystery infected hundreds of people

before dying out as suddenly as it began.

Like yawning, laughter is surprisingly contagious, kind of like a behaviour germ.

We’re much more likely to catch laughter from people we know,

which just goes to show how much more it is about bonding than humor.

In close relationships, couples who use laughter to cope with stressful situations tend to

stay together longer and report higher satisfaction. Laughter apparently helps us love.

"Laughing exercise for the heart and mind. What you can do? Just laugh. Very easy.

Don't feel shy!"

[laughter]

Laughter is amazingly hard to fake, and our brains are really good at telling the difference.

Listen to these clips and see if you can tell which one is real and which one is fake.

[laughter]

Younger people are less able to tell real laughter from fake laughter, but they are

more susceptible to contagious laughter, which is maybe why it’s easy to make a baby do

this.

[laughter]

But if we are so good at telling real from fake laughter, and laughter is ultimately

a form of communication, then why do we laugh at movies?

[laughter]

In the higher-order parts of our brain, we’re consciously awared that the actors we are watching are not present with us,

and that they are pretending.

But maybe the fact that we can laugh at what we know to be fake is the ultimate case of suspending our disbelief,

when we watch something on a screen, we really do believe the people

are right there with us, and that we know them, at least in some way.

Maybe we should all try and laugh more, and with each other.

It’s not only a way to feel better, but feel better together.

Stay curious.