Video: https://www.tiktok.com/@distilledscience/video/7535577439242685726
Transcript
Why did we evolve tickling? I'm going to tell you three theories that scientists have, and then you're going to vote on which one you think is most likely. Because we still don't fully know. We already covered how there's two different types of tickling. Nizmesis is that light, itchy touch that can happen anywhere, and we evolved mostly as a defense mechanism against bugs and ticks. Easy. But then there's the real stuff, gargolesis. The type that makes you laugh and is produced by firmer, more rhythmic motions. Only in certain locations is partially dependent on mood and context, and you can't do it to yourself. We know that we evolved this a long time ago because we see it in rats and monkeys. But the question remains. What sort of survival advantage does tickling give us that we kept it embedded so deeply in our psyche? Option one. Battle theory. Back in 1907, a scientist named Louis Robertson proposed that, because our most ticklish areas are the ones with vulnerable arteries like our armpits and groin, we evolved to reflexively pull away when someone tries to touch those areas, but to laugh and smile while doing so, ensure that our friends and parents try to touch us there. The problem with this theory is that there isn't really a perfect overlap between our ticklish areas and our most vulnerable ones. To see this, comment below with your order of most to least ticklish, across neck, armpits, stomach, and feet. More instructions later. Option two. Social theory says that we evolved tickling as a way to bond with our friends and family by establishing a tactile communication channel. They say that it helps infants develop a sense of humor, and it evolves towards sexual play with adults. The problem is that proponents of this theory say that we can only be tickled by people who have strong social ties to. But recent studies have shown that people laugh when they're tickled by a machine, who they're not friends with or related to. Option three, self-determination. You can't tickle yourself because your brain knows when and where that touch is going to happen and it mostly cancels it out, as shown by fMRI studies. And this is a good thing because imagine how terrible your life would be if you are accidentally constantly tickling yourself with every tiny touch. be dealing with a serial tickler. Some scientists think that we evolved the tickle reflex as a way of training our body's ability to distinguish between self-touch and other touch, which is partially based on the fact that people with neurological issues that heighten or alter the perception of self versus other can have altered levels of ticklishness, like touch aversion with autism. But that could be just a downstream effect rather than a main cause of the tickle reflex. And maybe we didn't evolve tickling to help us at all. And instead it's just a weird byproduct of mechanisms that we evolved for other more practical functions. So which do you think it was? And where are you most ticklish? Let me know in the comments if you dare.
Additional notes
Replying to @Randy McCarty In both humans and monkeys, the tickle response is stronger when young, lending some support to the theories that it plays a role in our early development and relationship between peers and parents. Vote for your theory + share your tickle map! Comment using this format: [Theory #]-[Most to least ticklish: Neck(N)/Armpit(A)/Stomach(S)/Feet(F)] Example: 3-A-S-N-F Key References: - Robinson, L. (1907). The Science of Ticklishness - Provine, R. (1997). Laughter: A Scientific Investigation - Blakemore et al. (1998). Central cancellation of self-produced tickle sensation - Harris et al. (1999) Can a machine tickle? #ScienceExplained #EvolutionaryBiology #Neuroscience #DistilledScience #tickling
References
- Robinson, L. (1907). The Science of Ticklishness.
- Provine, R. (1997). Laughter: A Scientific Investigation.
- Blakemore et al. (1998). Central cancellation of self-produced tickle sensation.
- Harris et al. (1999). Can a machine tickle?
- DOI/PMID numbers and direct source links not listed in workbook.