Why are people ticklish?

Hi I'm Craig, he he he, and this is Mental Floss on YouTube.

Today, I'm going to answer Tim B's big question, “Why are people ticklish?” No one knows for sure why people are ticklish. But, lucky for us, there are people who study this for a living. Lucky for them too that sounds like a great job. So, I'm going to talk about some of their findings today to tickle your fancy. What's a fancy? Let's get started! OH stop it, oh stop it In 1997, the writers of a study published in the journal “Cognition and Emotion” hypothesized that since people who are tickled laugh, they must already be in a happy mood.

They tested their theory by dividing 72 undergraduates into two groups. One group was shown comedy and Saturday Night Live clips before being tickled. Another group was shown an unfunny video before being tickled. It was probably a Wheezy Waiter video. For their theory to be correct, subjects would have had to laugh more while being tickled after watching the comedy clips.

But, the groups laughed equal amounts. That's science talk for people laugh while being tickled no matter what mood they're in -- meaning the laughter has nothing to do with actually being happy. Tickling was nothing more than a reflex. Another study, done in 2013 at the University of Tuebingen in Germany, found that tickling primarily activates two parts of the brain -- the Rolandic Operculum and the hypothalamus.

The Rolandic Operculum is also stimulated during regular laughter and emotions in general. But, the hypothalamus only activates during tickling, NOT other kinds of laughter. Interestingly, it's the same part of the brain that deals with pain and instincts (like fight or flight).

These two studies show that tickling is a reflex, so it probably evolved over time. We can't know why exactly, but scientists have some theories. According to expert Dr. Glenn Weisfeld (Is he German, what should my accent be?

“The structures of the body that are most vulnerable to tickling are also the ones that are most vulnerable to attack. We may be responsive to tickling because it gives us practice in defending ourselves. The scientists behind the University of Tuebingen study had a similar theory.

They believed that parents began tickling their children to prepare them to defend themselves. That's why I tickle myself, achaaaa! Another possibility comes from the book Laughter: A Scientific Investigation by neuroscientist Robert R. Provine.

He wrote that tickling originated as a form of social bonding. A parent tickles their baby, then the baby laughs in response. The tickling tends to stop when the baby starts to fuss, so the laughter ends. Thanks for watching Mental Floss on YouTube, which is made with the help of all these tickle monsters.

If you have a Big Question of your own that you'd like answered, leave it below in comments. See you next week!