Why Are We Ticklish? Why do We Laugh?

Hey, Vsauce. Michael here.

And today we're going to talk about humor, comedy. What makes something funny, and when something's funny, why do we laugh? What's the purpose of laughing, and why do we laugh when we're tickled?

Well, people study this. They're called gelotologists, and we don't have all the answers yet, but what we do know is that you are thirty times more likely to laugh if there are other people around. We also know that babies laugh before they learn a language and that babies born blind and deaf will laugh. There are thousands of languages, hundreds of thousands of dialects, but yet we all laugh in much the same way.

Our brains are constantly looking for patterns - ways of understanding the world and predicting what's next. It's to our evolutionary advantage. And so when something begins in a way that we expect and then all of a sudden changes and surprises or delights us, we often react with laughter because we have just learned something. We've learned a new logical order.

This theory posits that things are funny because there's an incongruity between what we expected and what happened. Whether it's a dog dressed like a human or a clever use of wordplay. In other words, comedy is about learning. But once you've learned the new logical order of the joke, well, it ceases to be funny, which is why jokes are funny the first time, but not every other time after that.

Take a look at this percentage sign. Alright, so you know what a percent sign is. But besides the percent, there's also a permil and permyriad symbol. But that's not funny because even though it might be new information to you, it still falls right in line with the logic of the percent symbol.

But what Demetri Martin shows us with just one more line, you can make it look like a man cheering after taking a dump... well, that surprises us. But we don't only laugh when something's funny. What about tickling? How does that make any sense? Most of us don't like being tickled, but when tickled, we can't help but smile and laugh.

Well, a possible explanation is that tickling helps teach children at a young age proper defensive behaviors. Is it a coincidence that the most ticklish areas are also the most vulnerable and the ones that we instinctively cover when startled? Also, because being tickled makes the person laugh, it may encourage others to tickle them, teaching them these defensive skills.

Tickling may even play a role before you are born. In order to avoid being tickled, a baby gets into a better position to be delivered. Now, physically, laughing involves the epiglottis - a little flap thing that protects the trachea whenever we swallow, so that food and water doesn't go down into our lungs.

I know it doesn't look very funny, but this is where the laugh happens. The epiglottis constricts the larynx, and we get the LOL. Interestingly, the epiglottis actually has taste buds on it, which means that, anatomically speaking, comedy truly is a matter of taste.

Get out of my house! And as always, thanks for watching.