Learn about how disgusting sights literally turn your stomach; and why tattoos are permanent. Then, play along at home as we test your podcast knowledge in this month’s edition of the Curiosity Challenge trivia game.
Learn about how disgusting sights literally turn your stomach; and why tattoos are permanent. Then, play along at home as we test your podcast knowledge in this month’s edition of the Curiosity Challenge trivia game.
Disgusting sights literally turn your stomach by Cameron Duke
Why are tattoos permanent? by Cameron Duke
Episodes referenced in the Curiosity Challenge trivia game:
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Find episode transcript here: https://curiosity-daily-4e53644e.simplecast.com/episodes/disgusting-sights-literally-turn-your-stomach
CODY: Hi! You’re about to get smarter in just a few minutes with Curiosity Daily from curiosity-dot-com. I’m Cody Gough.
ASHLEY: And I’m Ashley Hamer. Today, you’ll learn about how disgusting sights LITERALLY turn your stomach; and why tattoos are permanent. Then, play along at home as we test your podcast knowledge, in this month’s edition of Curiosity Challenge trivia.
CODY: Let’s satisfy some curiosity.
You know that queasy feeling you get when you pour chunks from a carton of expired milk you just found in the back of the fridge? You might say the experience “turned your stomach.” Well, recently, scientists explored what’s going on there, and they discovered that that description is more accurate than you’d think. Disgusting sights literally turn your stomach.
That familiar queasy feeling is caused by an interruption in the nerve impulses in your stomach. Normally, your brain sends rhythmic impulses to your stomach and intestines that make the muscles in your stomach lining contract and relax. This rhythmic pulsing keeps food moving through your digestive system. If those signals are interrupted, you start to feel nauseous.
Scientists have known that disgusting smells can interrupt these impulses and make us queasy, but a recently published study suggests that merely seeing something disgusting is enough to affect our stomach behavior.
That study came from a team of researchers at the University of Cambridge, who performed an experiment with a group of 25 terribly unlucky volunteers. The volunteers were divided into two groups, and the experiment had three rounds. The first round involved showing both groups a series of images. Many of the images were neutral, like a picture of a scarf or buttons, but they were mixed in with pictures of things that were downright gross, like human feces and rotting food. Both groups found the images to be about the same level of disgusting.
For the second round, things got interesting. One group was given an anti-nausea drug that steadies rhythmic nerve impulses to the stomach, while the other group was given a placebo. The researchers then told the participants to stare at the gross images for as long as they could stand it. To provide an incentive, the volunteers would be paid real money — the longer they looked, the more they were paid.
In the final round of the experiment, the researchers showed the two groups disgusting images again, but this time without offering them cash.
Even though both groups initially rated the images as being equally gross, the group that received the anti-nausea drug was able to look at the gross images for significantly longer than the placebo group, even when they weren’t incentivized to do it. That shows that the rhythms of our digestive muscles play a role in our aversion to disgusting images.
So the next time you see something gross, just go with your gut and look away.
When you get a tattoo, a bit of ink gets injected into the deep layers of your skin, where it tends to stay. But your skin is a living organ that’s constantly regenerating itself. So why don’t those stained skin cells die and flake off, taking your tattoo with them? It all comes down to the strange behavior of your immune system.
Your immune system is involved because a fresh tattoo is basically a wound. I mean, a needle has just torn a bunch of tiny holes in your skin, and your body’s gonna need to heal. So as a response, your repair systems engage. First, your blood vessels dilate so platelets can form clots and stop any bleeding. Next, skin cells begin regenerating to fill in the gaps. At that point, your immune system takes the call: white blood cells called macrophages show up to try and kill any germs that may have been sealed in by the scabs.
Your immune system’s involvement in the healing process is super important to prevent infections. If any harmful microbes have invaded, your macrophages are the next line of defense after your skin has been breached.
You might be imagining these macrophages like a squadron of biological Navy SEALs storming into battle to defend your body from microbial monsters, but that’s not entirely accurate. Instead, macrophages meander to the site of the tattoo to vacuum up any germs or foreign particles, like a bunch of immune-boosting Kirbys. They don’t discriminate. They try to eat everything they don’t recognize, and tattoo ink is one of those things. Macrophages swallow the ink, but they can’t break it down. So it just stays there inside of them.
Stained macrophages then take up residence in the middle layer of your skin, called the dermis. Eventually, these macrophages die and spill the ink back into the dermis. That leads other macrophages to jump into action and scoop up the spilled ink, which they can’t break down either, so it just stays there. So as your skin cells regenerate, macrophages keep dying, spilling ink, feasting on ink, and hanging out, over and over again.
It’s not your skin that’s stained. It’s your immune system showing through.
It’s time once again for the Curiosity Challenge! Every month, I call up a listener and put them to the test by asking three questions from stories we ran on Curiosity Daily in the previous month. For this Curiosity Challenge, I talked to Poornima [poor-NEEM-ah] in New York. She's an engineering student and science communicator who first started listening to Curiosity Daily with her family on their Google Home device. Have a listen!
[CLIP 3:01]
Nice work, Poornima. How did YOU do? If you’d like to play next month, OR if you have a question you’d like us to answer on the show, shoot us an email at curiosity at discovery dot com, or leave us a voicemail at 312-596-5208!
Leave us a voicemail at 312-596-5208!
CODY: Before we recap what we learned today, here’s a sneak peek at what you’ll hear next week on Curiosity Daily.
ASHLEY: Next week, you’ll learn about why sensitive questions don’t make conversations as uncomfortable as you might think;
The hot debate around how ice skating actually works;
Why your dog’s paws smell corn chips;
And more! You’ll also hear from author Jen Sincero about why we need habits and what most people forget when they’re trying to build new ones.
Okay, so now, let’s recap what we learned today.
[ad lib optional]
CODY: Today’s stories were written by Cameron Duke, and edited by Ashley Hamer, who’s the managing editor for Curiosity Daily.
ASHLEY: Scriptwriting by Cody Gough and me, Ashley Hamer. Curiosity Daily is produced and edited by Cody Gough.
CODY: Have a great weekend, and join us again Monday to learn something new in just a few minutes.
ASHLEY: And until then, stay curious!