Unexplainable - Why are there lefties and righties?

Episode Date: November 13, 2024

This week on Unexplainable or Not, we’ve got three scientific mysteries all about left and right. Jonquilyn Hill, host of Vox’s new podcast Explain It to Me, is going to guess which of them has been solved and which ones are still unexplainable. Guest: S. Furkan Ozturk, researcher at Harvard University For show transcripts, go to vox.com/unxtranscripts For more, go to vox.com/unexplainable And please email us! [e-mail] We read every email. Support Unexplainable by becoming a Vox Member today: vox.com/members Learn more about your ad choices. Visit podcastchoices.com/adchoices

Hey, I'm Matt Bouchelle, comedian, writer, and floating head you may or may not have seen on your FYP. And I'm starting a brand new podcast. Wait, don't swipe away. It's called, That Sounds Like a Lot. You know that feeling when you check your phone, read a few headlines and think, that sounds like a lot. I can't do this. Well, I can, and I'm going to get into it every Friday. You can watch on YouTube or listen wherever you get your podcast. I'm going to start by breaking down whatever insanity is happening in the world. And then I'll sit down with a comedian or actor or writer or, honestly, anyone who responds to my DMs. This is not the place to get the news, but it is a place to get the news.

to feel a little bit better about it. That sounds like a lot. Coming May 1st, part of the Vox Media Podcast Network. This is Unexplanable or Not, the game show where we finally get some answers. This week, our guest is Junklin Hill. She's the host of Explain It to Me. Vox's new podcast, all about answering listener questions. Welcome, JQ. Hello. I'm so excited to try to answer whatever y'all give me. Yeah, you ready to explain science to us? Um, no. But, But I will try my best. Okay. So Unexplainable or Not is a game show where you have to guess what we know and what we don't.

You're going to hear three scientific mysteries. And you're going to hear them from me, from our supervising producer Meredith Hodna. Hey there. And from our senior reporter producer, Bird Pinkerton. It's me. I'm the best one. No contest. So two of these mysteries are still unexplainable.

But one of them has recently been solved. After you hear all the mysteries, you're going to get a chance to get a chance to guess which one you think scientists have actually explained. And this week, in honor of your show, explain it to me. We're going to be telling you mysteries inspired by a listener question. Ooh, I love this. Actually, one of your listeners. Yay. Your producer, Sophie, sent us this question. So, uh, here it is. Hi, my name is Piper. I consider myself to be a relatively intelligent person, at least of average intelligence, but I'm 24 and still get my left and right confused. I've met a couple people like that in my life, and I'm wondering, what's wrong about,

for lack, the better word? Why do some people have a harder time than others distinguishing their left and right? So we loved this question so much that we wanted to spin up a whole game show around it, three mysteries all about left and right. Ooh, I love this. What's your relationship to your left and your left and your right? You're right. Okay.

So now I'm a gym girlie. Like in a perfect world, I get up early and I go to the gym before work. The world is often not perfect. But I sometimes work with a personal trainer and he'll tell me like, okay, you're a left hand and I'll raise my right. Oh, man. I consider myself a very smart person. But when it comes to physical activity, I'm a clumsy little potato.

I don't know why. So I understand where Piper is coming from on this. Very relatable. Okay. So this is a perfect question for you. Yeah. And actually, Bird is going to start with Piper's question. Yeah.

So, Junklin, like you, I also cannot tell my left from my right, which was great because when we were first introducing these questions, Noam was like, I just don't know about this because, like, I feel like everyone couldn't tell their left from their right. And I was like, hmm, interesting, no. Drag me. What a fun assumption to make. So to research this, I called up Inika Fonderham. She's a professor at Leiden University who studies spatial functioning. So that's everything from like how we remember where our car keys are to like how do we try and get from point A to point B. I feel like this woman could save my life in multiple ways. And so I read her this question basically. I like read her Piper's thing in full. And the very first thing she said is that, quote,

There is nothing wrong with this person. This is a natural phenomenon. You're really dragging me. This is terrible. Noam's the weirdo. Shocking. So she said essentially, like, our front is not the same as our back. Our top, like our head is not the same as our bottom, our feet.

So it's not hard to sort of tell those apart. But left, right, like, we're kind of symmetrical, right? So it's understandable that it's harder. But it is super weird here, right? Because there are some people, Noam, who just can do this on. automatically. Like, they just know. I'm never going to stop. And then there are some people, like me, like JQ, the normies of the world, who, you know, they have to like make a little L with their fingers. And you're like, okay. Is this L normal or is it backwards? Like, oh, the normal L is left side. For me, as like a little dyslexic child, I was like, but they're both elves. I don't understand. Okay. And then there's a third category, which is Meredith, who's just lost.

But Ionika wound up doing a large study where they basically showed people like a stick figure with little ball hands. So one hand was white and one hand is red. And the figure could be like facing you or facing away. And they would basically ask people to say like, is the red hand on this stick figure on the left side or the right side, for example? And it turns out that like when the stick figure was turned away from people, so the stick figure is. figures right was their right and left was their left, it was way easier for them to tell left and right apart, which suggests potentially there were all kind of consulting our own bodies in some way to figure out left and right in the world, like whether or not we can do that

more automatically. We're referring to ourselves in doing this. But that still doesn't really answer the question of like, why do some people do this automatically? And, And others like myself, like you, why do we have a harder time? That is still something that she needs to figure out. Or is it? And did she already solve it? Oh, my gosh. So what's your initial reaction?

What do you think? Do you think we know the answer to left-right confusion? Oh, man. This could be me being delusional, because again, I think this woman could fix me. But maybe we found it out. I think maybe. Maybe.

Maybe. Okay. So next up, I've got a mystery for you, which is why are there lefties in the first place? Ooh, I was almost left-handed, but I switched at the end. What? At the end of what? That's a direct quote from my mom. Like, okay, so apparently when I was a little kid, I would do everything with my

left hand, like everything. Then all of a sudden it was like, okay, write your name. And once that started, I was just like, all right, right hand. I was almost left handed, but didn't quite make it. Okay. So that feels like some kind of social influence. And when I started thinking about this question, I kind of thought that was what was behind lefties and righties. Like, you'll often hear that the reason there's so few lefties is because all these countries and cultures have been really anti-lefty, you know, sinister. The word sinister is from Latin for left. Oh, I didn't realize that.

Gosh is French for left, Bird told me that. Blame the French. But it's not just a social thing. You can see this actually really early on. So when you take an ultrasound by the 15th week in the womb, a fetus will already show a hand preference. Oh, wow. So 85% of fetuses are just moving their right hand a lot more than their life.

I was going to say, what are they doing with their right hand? They're just kind of moving it around. Okay. Got things to do. And it's not just humans. Like, chimps are mostly righties. Gorillas are mostly righties. Dogs, cats.

Even crabs have handedness or some kind of like clawedness where they have one preferred claw. So it's definitely not just a social thing. But then what is it? Like, where do lefties come from? So I talked to Veronica Odinsova, who's a researcher at Frye University in Amsterdam. And she said there are a couple basic ideas. of what might make someone a lefty.

So the first one is genetics, right? Like maybe there's a gene somewhere that makes you a lefty. So some studies have kind of compared identical twins with fraternal twins. And they basically come to the point where scientists say it's about 25% genetics. It plays a role, but it's not the main thing that makes someone a lefty. And when I asked Veronica what the main cause is, she basically said scientists just think it's random. So here's what that means.

There's lots of just stuff happening in our bodies all the time. Like, genes set out rules for stuff to happen. But then all the cells and everything inside the cells, they're all just bouncing around. So random. Yeah, this one scientist I read called it a jitter in the system. Oh, my gosh. Which is just kind of this crazy way to think about what's going on in our bodies. Like, we think there's this order, and it just seems like we're walking agents of chaos all the time.

That actually. Yeah. And there are apparently like 41 gene locations that influence left-handedness. What? Yeah. Then we're trying to imagine how these 41 genes are coding for all these things that are bouncing around all the time. Like, we haven't figured out the math that could predict this. And we still can't explain what's going on other than just saying it's random.

Do you ever stop and think, wow, being a person is so wild? Like, our hearts are beating and we're breathing and we're breathing. We're not even thinking about it. And we've been doing it this whole time. But maybe we have figured this out and we have gotten the math right. And we do know why lefties and righties are the way they are. Ooh. It's also possible.

I don't know. I just feel like if you're, I will be honest, I was not the best in math. Me neither. Like when my friends were, you know, in AP calculus, I was like, I will put all my brain power towards those English AP classes. Like, that was my vibe. So I am convinced that people who are good at math can, again, fix me. I'm convinced. Okay.

So our third and final mystery comes from our supervising producer, Meredith Hodnott. All right. So we've been talking a lot about handedness this whole time. Yeah. So let's take a look at them. You got fingers, you got thumbs, you got palms, you know, hopefully all in the right number and in the right order. and they're mirror images of each other. You see this when you like put on a left glove on your right hand,

the thumbs on the wrong side, it's all backwards. Well, this handedness shows up all the time in chemistry. Oh. It's called chirality from the Greek word for hand. And I talked to researcher Furkan Ozturk about this. He said that two molecules can have all the same parts and be connected in all the same ways, and yet be mirror images of each other, basically a left and right-handed version of the exact same molecule. So in a lot of chemical reactions, like man-made

chemical reactions in the lab, the left-and-handed versions are all mixed up together in like a 50-50 ratio. But sometimes a molecule's chirality matters a lot. Like I was an organic chemist before I got into audio. Oh my gosh. Why are you up? But were you good at math, Mara? I honestly wasn't that great at chemistry. I treated it a lot like cooking. I was just like, a little bit of this, a little bit of that. And unfortunately, that doesn't work out the best of yields. And then you were like, I know what to do podcasting. That's the way to go. So sometimes when I was at the bench and like working on a reaction, it'd be like off by half. And I just like couldn't figure out why. And it'd be like making a cake and like only having half of the flour mix in and just the other half just like

refusing to participate. And it'd be because I was using a mixture of both the left and right-handed molecules and only one was working. That, what? Oh my gosh. I mean, there's like a pretty classic tragic example. The medicine thalidomide was prescribed to pregnant people in the 1950s as a mixture of both the left and right-handed versions. And one version of the molecule was like a really effective treatment for morning sickness. And the other one caused severe birth defects. Oh my gosh. Even though they were the exact same molecule, just different mirror images of each other. So this is something that, you know, scientists have known about for a while. But the crazy thing is that there's one place where we don't see a mixture of left and right-handed molecules together.

And this is in all the molecules that have to do with life. Again, people. Wow. So this is like DNA, RNA, proteins, sugars, like throughout the natural world. So like not man-made chemicals in a lab. These life molecules only exist in one mirror form or the other. It's never a mixture. DNA is always right-handed and proteins are always left-handed. And this is a mystery that is stumped biologists and chemists for over 150 years

because this homo-chirality or same-handedness is basically a signature of life as we know. And not just humans, right? Like plants, everything? Yeah. From like the tiniest microbe to the most complex organism. Like life is this big weird bucket. It's really hard to define. There aren't a lot of things that are connecting all living things on earth. But on a molecular level, whatever life uses a chiro molecule, it only uses one-handedness. So to have something like this be such like a bedrock, fundamental truth of life, The reason why must go all the way back to like the very origins of life itself. Okay.

So, Jeky, what do you think? Do you think we've figured out why life only has one kind of molecule, either left or right, but not both? Ooh, I don't know. That's a huge-ass mystery, y'all. That's a big old mystery. Yeah. It's true. All right.

So we got three mysteries. There's the mystery of left-right confusion. There's the mystery of why are their lefties in the first place. And then we've got this mystery of why molecules of life are either lefty or righty, but never both. They're all unexplainable, or at least they all were unexplainable at one point. One of these mysteries has recently been figured out. And you'll have a chance to guess after the break. It's all about you.

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Their mile high tea with all the little cakes and sandwiches is a showstopper. Go to virginatlantic.com to learn more. I'm Maria Sharpova and I'm hosting a new podcast called Pretty Tough. Every week, I'm sitting down with trailblazing women at the top of their game to discuss ambition, work ethic, and the ups and downs that come on the path to achieving greatness. We'll dive into their stories and get valuable insights from top executives, actors, entrepreneurs, and other individuals who have inspired me so much in my own journey. Follow Pretty Tough wherever you get your podcasts.

I'm a Sted Hearnden, and this is America actually. We're all talking to each other to see what did we do wrong? What did we not see? I'm in Washington, D.C. this week to interview Ruben Gallego. He's a Democratic senator from Arizona, and he's been thinking openly about running for higher office. But he's recently run into some hot water because of his connection to Congressman Eric Swalwell. I have to learn from this, and I will learn from this. But for me, it's not a 2028.

question. It's about what it means to be a better first boss in my office and also a better senator to my constituents. This week on America, actually, we asked Gallego about predatory behavior in Washington. His plans for immigration reform

and more. It's unexplainable or not, JQ, welcome back. Hey. So we got three mysteries, but one of them has had a recent breakthrough. Mystery one. Why do some people struggle to tell their left from the right.

Mystery two, what makes someone a lefty? And mystery three, why does life have this weird rule about only having either left or right-handed molecules? So, without making your final guess, tell me what you're thinking after you've heard all three mysteries. Okay. First of all, I want to know the answer to all of these. And the fact that there is no answer to the two of them has to be shaking my fist at the

guy. I'm leaning towards left-right blindness just because I feel like knowing why we're right and left-handed and knowing why molecules are also right and left-handed. I realize it's not the same problem, but it feels like the same problem to me. Okay. So you think left-right confusion is the thing. Yes. But that could also be because I want to get an answer for Piper and for me also. That makes sense. So is that your final? answer, left-right confusion? Yes. All right.

Left-right confusion. Locking it in. Boop-boop. Meredith, sound effects. Do-do-do-do-do. So, JQ, here's your answer. Turns out that a lot of molecules exist as symmetrical pairs. Oh.

Turns out we've had a breakthrough on why molecules of life only exist as either left or right-handed. Wait. How's explain? Meredith, care to explain. Yeah, so we just heard from Furkan Oss Turk, and he's a postdoc at Harvard and Cambridge University. I'm a physicist by training, and I'm working on origins of life. And Furkan and his collaborators might have found a clue to why the chemistry of life never uses a mixture of right and left molecules. So because this is such a fundamental thing across all of life on Earth, he started thinking about the origins of life.

Without figuring out why homo-car reality happened, we cannot really understand how life emerged on Earth. To be clear, we have not solved the origins of life. I was going to say, girl, you about to bring some news to me? I was locked in. That would be a much bigger deal, and you would not be hearing about it on a game show. But scientists do have a whole bunch of different theories of how life could have started. And one of those theories is that life could have started. with a molecule involved with the genetic blueprints for life,

a building block for a molecule called RNA. So not something from life itself, but a potential precursor. And this building block molecule just happens to be chiral. So it's one of those kinds of molecules that have mirror images, so both a left and a right-handed version. And with all this in mind, Furcon focused on magnets. Most magnetic minerals and electrons through their spin can strongly couple to molecules' chiral structure. It turns out that chiral molecules, they can either be attracted to or repelled by a magnetic field,

depending on whether they're left or right-handed. And minerals, rocks with lots of iron in them, can be magnetized by the Earth's magnetic field. They're very abundant on early earth. They have been detected in minerals that date back to like 4 billion years old, and it was everywhere. So Ferkon thought that these magnets might have been like a physical way of organizing like a primordial soup of left and right-handed molecules. And it could have had like a knock-on effect and ended up making like a bunch of other life molecules single-handed as well. So Furkan decided to put this to the test. What we did is in the lab, we made these magnetic minerals. We magnetized them with magnetic fuels.

And he put a 50-50 mixture of left and right-handed molecules, this RNA building block on top of a magnet. Just a regular magnet? I imagine it's very strong. Yeah, just a regular magnet. Like in a way, like recreating that primordial soup on top of a magnetized lakebed in earlier. And then that's where the magic happens. The soup began to form crystals. And the crystals that formed on the magnetic mineral was only one-handed.

The magnet was separating these left-and-handed molecules from each other, locking all the right-handed ones into a solid crystal, and leaving all the left-handed ones just floating around in the soup. So while we still don't know the origins of life, this might be a clue to some pretty fundamental early-earth chemistry. that made life possible. I was, like, very, very excited, and a right-of-way emailed, like, our collaborators, and he got back to us, like, immediately, and he said, like, you bloody well, them cracked it. Furcon still has a lot of questions.

Like, he used a really strong magnet in his experiment, so he wants to try it again on, like, naturally formed magnetized rocks from across the world to see if it could happen under even more naturalistic conditions. Other sorting forces might have played a role like polarized light or radiation from cosmic rays. But solving this mystery won't just give us insight on our own history. You know, it'll help us look out into the universe and decide, you know, where life could have developed somewhere else in this big old universe of ours. Wow.

I feel like I'm going to be thinking of it a lot more. And the next time I work with my personal trainer. And he's like, you don't know you're right from your left. It'll be like, no. And no one knows why. Leave me on. So one last thing before you go. Even though you didn't win, we do have a consolation prize for you.

Ooh. Is it your friendship? I think we have two consolation prizes for you. We've got a tradition on our show where at the end of the game show, I write a song about the revealed mystery. Ah, I love music. So I sampled one of my favorite left-right songs, and I wrote something for you. Yay!

We're going to get funky. Spin to the left. Ah! Spin to the right. Anyway, you're looking at symmetrical. Let's go to work. Some molecules might have a left and a right, but life just isn't that flexible. Everybody clap your hand.

Protein. Right to the right. Don't have anything next. In the ancient verse. Made stuff. The ancient word. And the molecules are lies, picked aside, and they didn't. Chris cross.

How do scientists know if things can make life? I don't know. You tell me. The key just might be if they're only left or right. Take them to the bridge. Everybody clap your head. Proteins slide to the left. DNA.

Slide to the right. And if you don't have. have anything to do with life. I'm going to hear y'all. Peace, please. Wow. I love my job. Me too.

We need to create a line dance for this song specifically. I'm going to... You need, like, slide to the left, and then everyone's like, which left? Yeah, and then you actually slide to the right. That's amazing. Oh, wow. That's it for Unexplainable or Not. Thank you to JQ for coming on the show.

Thank you to our presenters, Bird Pinkerton. You're welcome. And Meredith Hodnott. Anytime. And thanks to our audience for joining us. If you have a mystery or a solved mystery you want us to tell on an upcoming game show, let us know. You can write us at Unexplanable at Vox.com. We read all the emails.

And that's it for Unexplanable or Not. Goodbye. This episode was reported by Bird Pinkerton, Meredith Hodnott, and me. No, I'm Hassanfeld. Production and music for me, editing from Meredith, who also runs our team, mixing in sound design from Christian Ayala, fact-checking from Anouchequing from Anoucdo-Soe, and tons of great vibes from Mending Win. Thanks so much to Johnclan Hill for playing our game this week. You can find her show, Explain It to Me, wherever you listen. They cover questions like, is my dentist scamming me? Or why do people say like so much? It's a great listen. Don't miss it. Special thanks this week to Noemi Globus. And thanks, thanks as always, to Brian Reznik for co-creating. our show. If you have thoughts about the show, send us an email. We're at Unexplainable at

Vox.com. And you can also leave us a review or a rating wherever you listen. It really helps us find new listeners. You can also support this show and all of Vox's journalism by joining our membership program today. You can go to Vox.com slash members to sign up. And if you signed up because of us, send us a note. We'd love to hear from you. Unexplainable is part of the Vox Media Podcast Network, and we'll be back next week. Side to the left DNA Side to the meat stars The ancient word

DIC decide and they didn't Chris cross