1 00:00:00,240 --> 00:00:02,320 Speaker 1: A brain Stuff listeners. If you're like me, I bet 2 00:00:02,400 --> 00:00:04,600 Speaker 1: you love to learn new things, and that's why I 3 00:00:04,640 --> 00:00:07,760 Speaker 1: want to tell you about the Great Courses Plus. It's 4 00:00:07,760 --> 00:00:11,640 Speaker 1: a video learning service that provides unlimited access to a 5 00:00:11,760 --> 00:00:15,840 Speaker 1: huge library of lecture series that are about totally fascinating 6 00:00:15,880 --> 00:00:19,200 Speaker 1: subjects like science, history, cooking, you name it. I think 7 00:00:19,200 --> 00:00:21,400 Speaker 1: that you should try it out. 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And now 15 00:00:44,960 --> 00:00:47,680 Speaker 1: the Great Courses Plus is offering brain Stuff listeners a 16 00:00:47,760 --> 00:00:50,920 Speaker 1: chance to stream hundreds of their courses, including that Neil 17 00:00:50,960 --> 00:00:55,920 Speaker 1: de grass Tyson series, which is dollars of value totally free. 18 00:00:56,160 --> 00:00:57,720 Speaker 1: All you have to do is go to the Great 19 00:00:57,720 --> 00:01:01,520 Speaker 1: Courses Plus dot com slash brain Stuff and it's yours 20 00:01:01,560 --> 00:01:04,759 Speaker 1: for free. That is the Great Courses plus dot com 21 00:01:04,800 --> 00:01:16,000 Speaker 1: slash brain Stuff. Welcome to brain Stuff from How Stuff Works. Hey, 22 00:01:16,040 --> 00:01:19,199 Speaker 1: I'm Christian Sager and this is brain Stuff pop quiz 23 00:01:19,240 --> 00:01:22,880 Speaker 1: hot shot. Have you ever tickled an ape? Before? It 24 00:01:22,920 --> 00:01:26,520 Speaker 1: could work as tickling as common between many types of primates. 25 00:01:26,840 --> 00:01:28,720 Speaker 1: What about a rat? You ever tickled one of those? 26 00:01:29,080 --> 00:01:31,640 Speaker 1: You'd know if you had, because rats let out these little, 27 00:01:31,720 --> 00:01:34,160 Speaker 1: high pitched chirps when you tickle them, kind of like 28 00:01:34,400 --> 00:01:37,920 Speaker 1: rodent laughter. Okay, so maybe some of you beast masters 29 00:01:37,959 --> 00:01:40,360 Speaker 1: out there have tickled both a rat and an ape. 30 00:01:40,600 --> 00:01:45,240 Speaker 1: But can you tickle yourself? Probably not, because that is 31 00:01:45,319 --> 00:01:48,600 Speaker 1: kind of impossible. Now, before we continue, let's do a 32 00:01:48,680 --> 00:01:52,320 Speaker 1: quick primer on how tickling works. Under your skin. There 33 00:01:52,320 --> 00:01:55,240 Speaker 1: are millions of nerve endings that alert your brain whenever 34 00:01:55,320 --> 00:01:59,040 Speaker 1: you touch something. A light touch, what we usually associate 35 00:01:59,080 --> 00:02:02,440 Speaker 1: with tickling, is analyzed by two regions of your brain, 36 00:02:02,960 --> 00:02:07,800 Speaker 1: the somato sensory cortex, which processes touch, and the anterior 37 00:02:07,960 --> 00:02:13,720 Speaker 1: singulated cortex, which processes happiness. Together they process the two 38 00:02:13,760 --> 00:02:18,920 Speaker 1: types of tickle sensations we can experience. The first is nismesis. 39 00:02:18,919 --> 00:02:21,440 Speaker 1: This is the light sensation you feel when something like 40 00:02:21,480 --> 00:02:25,359 Speaker 1: a feather brushes against your skin, maybe giving you goose bumps. 41 00:02:25,400 --> 00:02:28,800 Speaker 1: The second gargolesis is more like when your older brother 42 00:02:28,919 --> 00:02:31,600 Speaker 1: holds you down and tickles you until you laugh so 43 00:02:31,680 --> 00:02:34,320 Speaker 1: hard you pee your pants. This is the kind of 44 00:02:34,360 --> 00:02:39,440 Speaker 1: tickling you can't replicate yourself. Evolutionary biologists believe that the 45 00:02:39,520 --> 00:02:43,079 Speaker 1: reason we laugh when we're tickled is an innate, submissive 46 00:02:43,120 --> 00:02:46,280 Speaker 1: response to a potential attacker. It's kind of like when 47 00:02:46,280 --> 00:02:49,119 Speaker 1: a dog rolls over on its back and exposes its 48 00:02:49,200 --> 00:02:53,560 Speaker 1: kill points to you. These same biologists theorized that we 49 00:02:53,680 --> 00:02:57,200 Speaker 1: developed tickling so we could teach our children how to 50 00:02:57,280 --> 00:03:01,360 Speaker 1: defend themselves from attacks. So think about it. The areas 51 00:03:01,360 --> 00:03:04,400 Speaker 1: where we're the most ticklish, the under arms, the stomach, 52 00:03:04,520 --> 00:03:08,480 Speaker 1: the neck, they're also the most vulnerable to attack. Now, 53 00:03:08,520 --> 00:03:12,240 Speaker 1: this is some black Widow red room lethal training coming 54 00:03:12,320 --> 00:03:15,320 Speaker 1: up here, so pay attention. Your under arm is home 55 00:03:15,360 --> 00:03:18,200 Speaker 1: to veins and arteries, and because your rib cage doesn't 56 00:03:18,200 --> 00:03:21,919 Speaker 1: protect it, someone could easily access your heart through there, 57 00:03:22,120 --> 00:03:26,000 Speaker 1: especially with a long enough blade. Likewise, your stomach doesn't 58 00:03:26,040 --> 00:03:29,280 Speaker 1: have any defensive bones, and your neck also has two 59 00:03:29,280 --> 00:03:32,280 Speaker 1: important arteries as well as your trachea, bringing air to 60 00:03:32,360 --> 00:03:35,080 Speaker 1: your lungs now We're aware of all of these points 61 00:03:35,080 --> 00:03:38,520 Speaker 1: of vulnerability, but we still can't tickle ourselves at them 62 00:03:38,800 --> 00:03:42,280 Speaker 1: because our brains know that our own hands don't pose 63 00:03:42,360 --> 00:03:46,000 Speaker 1: a legitimate threat. Essentially, you can't tickle yourself because of 64 00:03:46,040 --> 00:03:49,559 Speaker 1: self awareness. Mri I studies have shown that your seahbellum 65 00:03:49,640 --> 00:03:51,960 Speaker 1: actually alerts the rest of your brain when you're about 66 00:03:52,000 --> 00:03:56,040 Speaker 1: to tickle yourself. This filters it out as unnecessary information 67 00:03:56,200 --> 00:04:01,440 Speaker 1: and mutes the sensation. So theoretically, any situation that confuses 68 00:04:01,480 --> 00:04:05,600 Speaker 1: your brain's ability to predict its own actions should allow 69 00:04:05,640 --> 00:04:11,600 Speaker 1: you to tickle yourself right well. Sometimes schizophrenics, for example, 70 00:04:11,640 --> 00:04:15,400 Speaker 1: can tickle themselves. This is probably because their brains sometimes 71 00:04:15,400 --> 00:04:21,039 Speaker 1: attribute their behavior to an alien source. Researchers theorized that 72 00:04:21,120 --> 00:04:26,640 Speaker 1: schizophrenic brains have biochemical or structural variations that keep the 73 00:04:26,680 --> 00:04:30,520 Speaker 1: cerebellum from alerting its owner when they're about to tickle themselves. 74 00:04:31,120 --> 00:04:34,040 Speaker 1: This means they can't tell the difference between their hands, 75 00:04:34,520 --> 00:04:42,640 Speaker 1: your hands, or the tentacles of a giant squint. Check 76 00:04:42,680 --> 00:04:44,720 Speaker 1: out the brain stuff channel on YouTube, and for more 77 00:04:44,760 --> 00:04:47,279 Speaker 1: on this and thousands of other topics, visit how stuff 78 00:04:47,320 --> 00:05:01,799 Speaker 1: works dot com.