Today we discuss the link between gastrointestinal disorders and mental health, how the path you take walking through a crowd can be predicted by mathematics, and how we’ve now witnessed an example of super propulsion in nature for the first time!
Today we discuss the link between gastrointestinal disorders and mental health, how the path you take walking through a crowd can be predicted by mathematics, and how we’ve now witnessed an example of super propulsion in nature for the first time!
GERD Anxiety
Crowd Math
Insect Catapult
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Find episode transcripts here: https://curiosity-daily-4e53644e.simplecast.com/episodes/gerd-anxiety-crowd-math-insect-catapult
NATE: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from Discovery. Time flies when you’re learnin’ super cool stuff. I’m Nate.
CALLI: And I’m Calli. If you’re dropping in for the first time, welcome to Curiosity, where we aim to blow your mind by helping you to grow your mind. If you’re a loyal listener, welcome back!
NATE: Today you’ll learn about the link between gastrointestinal disorders and mental health, how the path you take walking through a crowd can be predicted by mathematics, and how we’ve now witnessed an example of super propulsion in nature for the first time!
CALLI: Without further ado, let’s satisfy some curiosity!
[SFX: WHOOSH]
NATE: So we've talked a bit before about the age old concept of the mind body connection. But today I want to tell you about a very concrete example.
CALLI: Oh, okay. Already a good hook. I would like to hear more.
NATE: Thank you. Thank you. Have you ever heard of GERD before? It's gastro intestinal reflux disease and it's got some pretty awesome symptoms, like heartburn, involuntary regurgitation and chest pain.
CALLI: Oh, yeah, I've heard of it. I've never heard the long name before, but I do actually have some close friends who have to deal with this. But from what I've heard, it doesn't have anything to do with the mind. Right.
NATE: Well, hold on a second. We'll get to that. So a little bit of background. GERD is one of the most common gastrointestinal disorders and it affects anywhere between 10 to 20% of the global population. What's really interesting is that a number of studies have shown that people with GERD are more likely to develop anxiety disorders and depression.
CALLI: Okay. That does make sense to me. I mean, I understand I wouldn't necessarily be feeling my best if I was dealing with heartburn and chest pain all the time. But can you explain what exactly is going on when someone is experiencing GERD? Can you break it down for us?
NATE: Yeah. So acid reflux is a common thing that nearly everybody on earth has experienced. And it happens when a valve at the end of our esophagus doesn't close properly when food enters the stomach and this sends a backwash of stomach acid back up to the esophagus, creating a sour, acidic taste. But it's it is normal. And it's when acid reflux happens more than twice a week for several weeks, that things might get a little dicey because you could have GERD And GERD comes from the body constantly experiencing acid reflux. And it leads to things you mentioned like heartburn and upper abdominal pain, but also trouble swallowing and the possible feeling of a lump in your throat. And it will create an overall reduced quality of life, possibly even leading to complications like esophageal cancer.
CALLI: Okay. And so it's this reduced quality of life that's causing anxiety or depression.
NATE: Maybe it's kind of hard to say. So those studies also make it a little tough to link the condition to depression and anxiety because their results might be offset by factors like lifestyle habits, socioeconomic status or co-morbidities, which is when there are two or more diseases or medical conditions mingling together within the same person.
CALLI: Okay. And especially since depression and anxiety are so common, I can see how that would make connecting the conditions pretty difficult considering there are so many other moving parts to consider. So how would you even go about doing this study with all of these factors?
NATE: A team from Central South University did a Mendelian randomization study or an MR for short. It's a little complicated, so forgive the simplification here, but basically they looked into genetics and used statistics to find the likelihood that someone experienced GERD. They performed six analyzes and then added a seventh to adjust for any extra factors like whether a person smoked cigarets or drank alcohol or was overweight.
CALLI: So they had a space mercenary do a study.
NATE: Not mandalorian Mendelian Gregor Mendel. That's fine.
CALLI: Sure. Okay. So what did they find?
NATE: They actually found a huge link. So every single test the team ran showed that GERD significantly increases the risk of anxiety disorders in depression, even when the people they surveyed smoked were overweight or drank alcohol. On the flip side, they also found that if somebody had a history of anxiety or depression, it did not seem to increase their risk of developing GERD. That means there's now some pretty sturdy evidence that if someone has GERD and is suffering from anxiety or depression, it's very likely because of GERD.
CALLI: Okay, I'm glad there's a link now, but also that sucks. Like you get GERD, your body suffers and your mind suffers. Is there anything we can do about this?
NATE: The team recommends adding psychological treatment plans to any GERD treatment, psychological assessment, as well as any necessary psychological support. Therapy could really help somebody reduce the risk of any harm that comes from an anxiety disorder or depression. But to be fair, this study only used data from European people. We're going to need to do more studies to see if GERD and anxiety are linked in the same way in other populations. But this is a promising start for an otherwise previously understudied trek into. The link between gastrointestinal disorders and mental health.
CALLI: Wild. I'm going to have to tell my friends.
[SFX: WHOOSH]
CALLI: People just love to say that math is a subject that doesn't apply to their everyday lives, myself included. But I just came across a study that proves that this is absolutely false.
NATE: Okay, a math topic sounds great. Give me more info.
CALLI: Normally, I wouldn't be excited about a math subject, but this one's kind of fun. It turns out that if you've ever walked through a crowd surprise, you are actually using math. Have you ever noticed how when people fall into a crowd, they start walking as if they were in lanes, even if there are no lanes? Well, a team of mathematicians from the University of Bath in England investigated by recruiting a group of volunteers. They had walk across an experimental area they put together that was similar to King's Cross station in London as the volunteers walked. The researchers filmed them walking and then watched the footage. After noticing something interesting. Mathematical patterns were popping up in real life as the volunteers walked. So to the casual eye, it might have looked disorderly. After all, it's a bunch of people walking toward one location. But the team started noticing the volunteers weren't just walking chaotically or even just in straight lines. They were walking in more complex, curved patterns like ellipses, parabolas and hyperbolas.
NATE: Okay, forgive me. I'm not seeing what this has to do with math or science. I mean, it's not just random formation of how people are walking.
CALLI: No, that's the thing. That's that's what makes this fascinating. It's not nobody's talking about it. Nobody's acknowledging the phenomenon. But it's definitely happening all around us. And it has to do with the science of active matter.
NATE: All right. What is active matter?
CALLI: It's kind of a vague definition, but broadly, it's the study of behaviors within specific populations. So think of anything from flocks of birds to bacteria and how they navigate within their group.
NATE: Gotcha. Okay. So how an individual behaves when in a group?
CALLI: Exactly. It can even predict when these subconscious lanes are going to be straight lines or curved lines. What's even crazier is that the theory can account for a line will tilt when people are in the habit of passing on one side rather than the other. Similar to how when we drive in America, we're encouraged to pass on the left. So in their study, they force people to pass on the right. It's a pretty big theory that proves we were doing math even when we aren't thinking about it.
NATE: All right. Could could it all just be a coincidence?
CALLI: Well, that's the thing. They quickly found out it wasn't. They teamed up with the Academy of Physical Education in Poland and expanded the amount of volunteers they could use to make the area a bit more crowded and close to real life. This gave them enough data to create a mathematical theory that could accurately predict whether subconscious line formation would be straight, curved or tilted due to whatever subconscious traffic rules came up.
NATE: Okay, how does the theory work?
CALLI: So we'll back up a bit here. Have you ever heard of Einstein's theory of Brownian motion? It's really similar to that which describes the random flow of liquid or gas molecules colliding with one another in a specific area. So think about if you've ever sprayed room freshener or Fabreeze and how the liquid particles interact with the air, or when you see dust and the beam of sunlight moving around the room. That's Brownian motion, basically a bunch of micro calculations that allow the particles to coexist in harmony. Obviously, physics are hardwired into nature, and this theory suggests they're hard wired into our brains, too.
NATE: Gotcha. So much like the great poets in multiplatinum rock band Kansas once said, All we are is dust in the Wind.
CALLI: No.
NATE: Yes, but that's really cool. Does it matter what the area looks like? The shape and setup. For instance, I know that most pedestrian traffic will pass through zebra crossings, which are crosswalks marked by those fat white stripes on the ground.
CALLI: The team from Bath doesn't actually think so. No mathematical shapes and paths could possibly be created by any group of people anywhere. What's more is that these findings also provide us with the evidence that lane formations could pop up just about anywhere. And it doesn't have to be an animal or bacteria doing it.
NATE: All right. So what is it that we can learn from this study that they've done?
CALLI: Okay. Well, here's the takeaway. We've witnessed similar shapes pop up in the formations of molecules, meaning that there's a lot more structure both on a molecular level and socially than we ever thought. Right now, there's not any kind of bigger picture plan when it comes to, say, a practical application for this information. But that's not to say there won't be. So for now, what we have is something that researchers call a neat mathematical theory.
NATE: Love it.
[SFX: WHOOSH]
NATE: Well, today I'm going to teach you about super propulsion by talking about an insect that flicks pee from its butt.
CALLI: What? No.
NATE: That's a real story. That's the story. And the insects name is the Homalodisca vitripennis. Oh. But we can call it by its more common name. The glassy winged sharpshooter.
CALLI: Kind of want that as a gamertag. Not going to lie. Tell me more.
NATE: Be available. Well, this little guy. Beautiful, lethal and teaching us about engineering the ultimate trifecta. I can't really think of a good segue here, so let's just go for it. The sharpshooter pees up to 300 times its own weight every single day for perspective. Humans urinate about 1/40 of their body weight every day.
CALLI: That's great. I don't care. What does this have to teach us about engineering?
NATE: Getting there. But first, the sharpshooter is a close relative of the cicada and is, on average, about half an inch long. Their diet is super unusual for an insect like this. A lot of insects feed on the phloem, which takes sugar down to the leaves. The sharpshooter, on the other hand, feeds on sap that comes from the xylem, which is the woody part of a plant that brings water and nutrients up from the roots. And since it's mostly water, they pee a lot.
CALLI: You're giving me a lot of really good information, but I'm still really dying to know about the flinging of pee.
NATE: Okay. Okay. So it shoots drops of pee at super fast speeds from a sort of catapult attached to it. But for years, people have been flabbergasted by something called leaf hopper rain that occurs when sharpshooters begin flying. Can you guess what Leaf Hopper rain was? No. Exactly. A researcher at the Georgia Institute of Technology in Atlanta was doing a study on the physics of excretion, or how different organisms get rid of waste. That researcher, Saad Bhamla said he saw these insects peeing once and fell in love, realizing that leaf hopper rain might hold the secret to any clever evolutionary innovations. So his team used high speed imaging and microscopy in order to look into a certain part of the sharpshooters tail end. Bhamla called it the butt flicker. But its scientific name is the anal stylus.
CALLI: I can't believe I'm saying this out loud, but how does a butt flicker work, Nate?
NATE: Whenever the sharpshooter is ready to urinate, the butt flicker starts flexing downward as the sharpshooter squeezes out a single drop of urine into a shape that builds pressure in their surface tension. Surface tension is what makes liquid molecules attach together like raindrops on a window. When that drop becomes a certain size, the butt flicker bends even more and then suddenly launches the droplet. Think of the motion like a slingshot. It just flex the pee out at a speed of 1.05 feet per second. For perspective, that's ten times the speed of the fastest sports car and nearly 40% faster than the butt flicker, which only moves at a speed of 0.75 feet per second.
CALLI: That's fun. So the sharpshooter creates leaf hopper rain. That's actually bullet urine flicked like a pinball from its butt.
NATE: Now you get it.
CALLI: What does this have to do with super propulsion?
NATE: Well, because this is super propulsion, according to Charles Q. Choi for live Science. Super propulsion is when a projectile is launched, but it moves faster than the launch pad does due to a kind of energy boost it gets from sinking its movements up with the launch pad. Think of how a diver sinks their jump up with a springboard for the best momentum. Except with super propulsion, the diver is moving faster than the springboard. It's only ever been seen in artificial settings until we discovered the sharpshooter.
CALLI: Okay. I really can't contain myself here. This is genuinely the funniest possible way we could have discovered super propulsion in the wild. I've got to know, though, why does the sharpshooter pick out little drops instead of a sprayer or a jet?
NATE: The team wanted to know that too, so they used micro CT scans to analyze the bug’s internals and take some measurements. Fun. And they calculated the pressure and energy that sharpshooters need for peeing and realized that because of the super propulsive movement, the sharpshooters urinary trajectory actually expended 4 to 8 times less energy than a stream of urine would. Basically, they need all the energy they can get when they're peeing 300 times their own weight daily.
CALLI: Okay. This is probably one of the weirdest things we have ever talked about on the show, but also kind of one of the most amazing. What is what does this all boil down to?
NATE: No matter how weird it sounds, the implications of us finding super propulsion in the wild are huge. This could lead to breakthroughs in engineering, such as the ability to make self-cleaning devices that use less energy. Think about how water droplets usually stick to surfaces and how those droplets can drip into electronics and damage them. If we can develop a super propulsion technique similar to the sharpshooter insect, we could clean surfaces with as much liquid as we need, but say make the droplets simply fall off the surface by vibrating it at the same frequency as the droplets. Long story short, this is just another great example of how there are some really groundbreaking things in the world of science. And sometimes we can find them just outside our door.
[SFX: WHOOSH]
NATE: Let’s recap what we learned today to wrap up! If you have a gastrointestinal disorder and are experiencing anxiety, you’re not alone - and there’s a good chance it’s because of the disorder. New research suggests that there is a pretty solid causality between GERD and anxiety that explains that GERD might be leading to quite a few mental health issues. Our conclusion is that it wouldn’t hurt to get some mental health treatment when you’re experiencing GERD - because even if your body has to hurt, your mind might not have to!
CALLI: I’m walkin here, I’m walkin here - and I’m walkin’ in a preordained path! New research out of England reveals that when we walk in any crowd, all of us eventually begin to walk in predetermined paths of varying sizes and shapes. Using this information, the team has created a mathematical model that accurately predicts how and when a lane is going to form. So far, there are no plans for this to be put to any practical use, but for now, it’s evidence that math is something we use every single day - even when we don’t mean to!
NATE: Scientists have discovered an insect that can shoot pee at super speeds from a catapult on its butt. On a normal podcast, that’s the entire story. But on Curiosity Daily, it turns out this is because of super propulsion - which is when a projectile moves faster than its launchpad due to a kind of energy boost it gets. This is the first time we’ve ever seen this in nature, and researchers now believe this could lead to some incredible innovations in engineering of all kinds. And it all started with a bug that shoots pee from its butt.