Hey smart people Joe here. Ya know, we’ve explained a lot of weird
bodily functions on this show but there’s one that we haven’t covered that’s always
confused me: Tickling. It’s one of the great contradictions of
the universe, like jumbo shrimp, or saying “that’s your only choice”. (that doesn’t
make sense) Because tickling makes us laugh. But we hate it. Basically no one likes being tickled. Go tickle someone right now. Actually… I’m shooting this during COVID-19, physical
distancing, all that… so maybe don’t do that unless it’s someone in your house you’re
hunkered down with or this has all cleared up by the time you’re watching this. Also ask them permission first, otherwise
that’s just really rude (or maybe assault) but what happens? They might laugh, but the universal reaction
to being tickled is pretty much, “please stop, no thank you, SERIOUSLY STOP OR I AM
GOING TO BLEEP]” What are you for, tickling? What’s the point of you? Why do you exist?] We’re gonna dig down in the soft tummy tum
of science and see if we can shake out some answers to why we’re ticklish, what is it
really for, and what is it that makes tickling the unfunniest thing that makes us laugh. [OPEN] So, I know what you’re wondering: can you
tickle yourself? The answer? It depends! Because There’s actually two different kinds
of tickling. The kind of tickling we’re most familiar
with is called gargalesis. That’s the one that makes us freak out and
laugh and it’s the one you can’t do to yourself (that’ll be important later). Now almost everyone has been tickled before. We do it to make kids and babies laugh, maybe you do it when you’re feeling a little flirtsy with
someone you like. But it’s a real head-scratcher. Or armpit scratcher. Not a good image. People have been confused by tickling for
thousands of years. Aristotle attributed our ticklishness to the
softness of our skin, and us being “the only creatures” smart enough to find things
funny. Even my boy Darwin wrote about tickling. He didn’t exactly hit the nail on the head
– he thought that to be ticklish, you had to be in a good mood, which isn’t true – but
he did give us that one question we always have to ask for weird behaviors like this:
What’s the evolutionary purpose? I mean, tickling wouldn’t exist if it didn’t
have a biological purpose for us *or* to one of our species’ ancestors. And we’re gonna figure that out. Clue #1? This. Only some areas of our bodies are sensitive
to gargalesis. I mean, try to tickle someone’s shin, and
you won’t get much of a reaction. Get them here, though and … Turns out other primates tickle each other
too, when they’re doing a kind of rough and tumble play. This may hold some hints to why it exists. Our “ticklish spots” are really vulnerable
areas of our body. And I don’t mean “emotionally vulnerable”
I mean in the “this is where a predator or an attacker would try to get you so they
could kill you” You’ve got major arteries here, and here, and major organs and other
necessary-for-living parts, here, here, and here. So you recoil, you curl up in a ball, it’s
a reflex. Gargalesis probably evolved as a way to help
us protect ourselves. Those ticklish spots don’t really apply
to the other kind of tickling, Knismesis. That’s the tickle you feel when something
moves lightly across your skin. You can feel this almost anywhere on your
body, and it can lead to anything from goosebumps to those whole body shudder. Now, knismesis isn’t typically associated
with laughter, but some people do like it. And it’s kind of easy to see where it may
have come from. This kind of tickle is like an alarm going
off on your skin, you know, in case there’s like a dozen spiders crawling up your neck
or something, you’re gonna want to notice that. Definitely not funny. And that’s why it leads to involuntary twitching
and shuddering and scratching to get potentially-dangerous creepy crawlies off our skin. (Next time someone scratches your back, bet
you look at it differently). It’s just a physical touch reflex - and
you can do this kind of tickling to yourself. But this kind of tickling isn’t really associated
with laughter… …while gargalesis is. But why?! Why does tickling make us laugh? I mean, why doesn’t it hurt? Or burn? Or just tingle? Why the heck is trying to protect your internal
organs from would-be attackers FUNNY?! That brings us to clue #2: You can’t tickle
yourself. No matter how hard I try, I can’t tickle
myself with gargalesis. Why? For the same reason you can’t scare or startle
yourself. You’ve got a part of your brain that always
knows your next move. It’s why I can pick something up without
looking. My brain is predicting my movements, it’s
looking for feedback, making little adjustments. The point is my brain knows what I am trying
to do, and if I try to tickle myself, my brain overrides the whole tickling program. So for gargalesis, the laughy tickles, only
other people can tickle us. That tells us tickling is social. The same way that talking or facial expressions
send messages to each other, tickling is sending a social message too. So what’s the message? Scientists have done some pretty weird experiments
to figure this out. It turns out the person tickling us doesn’t
have to laugh for us to laugh. Even when someone wearing a mask tickles a
baby, the baby laughs. Kind of a creepy experiment. Don’t do that. And it turns out adults laugh even when they
think a machine is tickling them. Which is also a weird experiment. Now we’ve got two clues to help us figure
out tickling: #1 Our ticklish spots are vulnerable places we need to protect. And clue #2 You can’t tickle yourself. So maybe the reason we laugh is to get other
people to tickle us. Yeah, even though we hate it. Just hear me out.. If you tickled someone, and they started crying,
you’d stop. So laughter is positive reinforcement, it’s
a social message that makes the people tickling us happy, to encourage them to keep doing
it. Why should they keep doing it? Because rough-and-tumble play in animals is
an important part of learning and developing and growing up, and to our ancestors, it would
have been important for survival. It’s how we’d practice skills like fighting,
hunting, and protecting ourselves. On the flip side, if tickling was only about
laughter and pleasure - if it didn’t give you that “run away” feeling, you wouldn’t
recoil or fight back. Which doesn’t teach that important evolutionary
lesson about “protecting yourself”. And it turns out other animals laugh when
tickled too. Our primate cousins make a laugh-like ha-ha
sound during tickle play. And it probably goes back farther along our
family tree. You can even tickle rats, and people have
done it, for science. When they’re tickled they emit high frequency
noises. Why? I don’t know the mind of a rat, but the
high frequency sounds they make when tickled are the same ones they make when playing with
other rats and when they’re given food. Tickling seems to make them happy and the
laugh might encourage other rats to keep doing it. So, tickling is probably an ancient social
behavior from way back in our evolutionary past that helps animals learn how to protect
themselves. But more importantly, even though tickling
makes us laugh, that laughter doesn’t have anything to do with things being funny. And this is why tickling teaches us something
really important about laughter itself. We tend to think laughter is always tied to
funny things, but it’s not. (it’s snot… heh) There are people who study laughter, and they
are called “gelotologists”. And one thing we know from their research
is that more than anything else, we laugh for each other. People are more than 30 times more likely
to laugh when they’re with other people than alone. I’ve talked about that a little before. And we have also learned that fewer than 1
in 5 laughs are actually in response to humor. Seriously. Just watch two people have a normal happy
conversation sometime. In between the talking you’ll see a ton
of .... We laugh when we’re nervous, we laugh just to fill space in a conversation,
or just to tell the person we’re talking to that we’re listening. Most of the time, laughs are just… social
noise, they’re filler. Unless you’re laughing at my jokes, those
are real…. And have you ever been so sad, or so mad,
you laughed? It’s weird, but we know that to our brains,
the experience of social discomfort – or emotional pain – is a lot like physical
pain. We think laughing prompts our bodies to release
beta-endorphins, hormones that act like our body’s own painkillers. The point is laughter is one of our most complex
social behaviors. We use it to send lots of different messages,
most of which have nothing to do with humor, so it’s not surprising that its link to
tickling is… complex too. So here’s what we know: Tickling is almost
built into our bodies, it’s like a reflex. The places we’re ticklish are the places
we are most vulnerable. And even though we laugh, tickling isn’t
funny. We tickle each other as part of a weird and
complex kind of play that our evolutionary ancestors relied on to teach each other to
be safe, and laughter is the reward for our brain that makes us want to do it to each
other. Remember, we’re animals, and that’s why
laughing makes us feel good really deep down, and tickling can reinforce social bonds with
the people we love. I TAKE IT BACK I DON’T LIKE SOCIAL BONDING.
