Radiolab - Signal Hill: Caterpillar Roadshow

Episode Date: April 11, 2025

A couple years ago, an entomologist named Martha Weiss got a letter from a little boy in Japan saying he wanted to replicate a famous study of hers. We covered that original study on Radiolab more than a decade ago in an episode called Goo and You – check it out here – and in addition to revealing some fascinating secrets of insect life, it also raises big questions about memory, permanence and transformation. The letter Martha received about building on this study set in motion a series of spectacular events that advance her original science and show how science works when a 12-year-old boy is the one doing it. Martha’s daughter, reporter Annie Rosenthal, captured all of it and turned it into a beautiful audio story called “Caterpillar Roadshow.” It was originally published in a brand new independent audio magazine called Signal Hill, which happens to have been created in part by two former Radiolab interns (Liza Yeager and Jackson Roach, both of whom worked on this piece), and we loved it, so we’re presenting an excerpt for you here.Special thanks to Annie Rosenthal, Liza Yeager, Jackson Roach, Leo Wong, Omar Etman, the whole team at Signal Hill, Carlos Morales, John Lill, Marfa Public Radio and Emma Garschagen.EPISODE CREDITS: Reported by - Annie RosenthalProduced by - Annie Rosenthalwith help from - Leo Wong and Omar EtmanSound design contributed by - Liza Yeager and Jackson RoachFact-checking by - Alan Deanand Edited by  - Liza Yeager and Jackson RoachEPISODE CITATIONS:Audio -  Listen to the original Radiolab episode, Goo and You, here (https://zpr.io/qh9xqpkXzk7j).Or the Signal Hill podcast here (https://zpr.io/CDfwyK7Zkrva).Guests - And if you want to learn more about Martha Weiss, and her work, head over here (https://zpr.io/aBw2YsqWB6NZ).Signup for our newsletter!! It includes short essays, recommendations, and details about other ways to interact with the show. Sign up (https://radiolab.org/newsletter)!Radiolab is supported by listeners like you. Support Radiolab by becoming a member of The Lab (https://members.radiolab.org/) today.Follow our show on Instagram, Twitter and Facebook @radiolab, and share your thoughts with us by emailing [e-mail] support for Radiolab’s science programming is provided by the Gordon and Betty Moore Foundation, Science Sandbox, a Simons Foundation Initiative, and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.

Did you know Radiolab has a new live event series called Viscera with ER doctor Avere Mitra? Well we do, and we are bringing a new show to New York City on April 22nd. Join me, Lulu Miller, and Avere, and a bunch of experts as we talk about wild new discoveries in an ancient elixir. That's Viscera, Elixir of Life at the caveat theater, Tuesday, April 22nd. Doors at 7, get your tickets at caveat that's see a vea t.com oh wait you're listening okay all right okay all right

you're listening to radio lab radio from w and weiss from WNYC. See? Yep. Hey, I'm Molly Webster. This is Radiolab. So one of my first pieces at the show, like actually kind of my very first Molly piece, was this episode called Goo and You. It was about what happens inside a chrysalis when a caterpillar crawls in and a butterfly

or moth crawls out, like what happens in that middle space. And it's one of my favorite pieces because it feels like, I don't know, it's got like science and poetry and philosophy and it's also just this meditation on what it means to change. And though it was my first piece, which happened over 10 years ago, it is still actually the piece that I get the most feedback about. Like, I still get emails about it. People want me to do workshops on it. It inspired some famous persons like Wedding.

And then a month ago, it popped up again when one of my editors was like, yo, Molly, this fabulous young radio reporter basically made a goo and you sequel. I listened to it. It's great. It's a story that revisits the scientist, drags her whole family in to this kind of international tale, and then it becomes a meditation not just about change in an individual, but across generations. And so what we want to do for you is play an excerpt of this piece. It's called Caterpillar Roadshow. It's from this audio magazine called Signal Hill.

And the reporter is Annie Rosenthal. So here's Annie. In the spring of 2022, my mom went into the mailroom at the university where she works in D.C. In her box, there was a big flat envelope addressed to her, Martha Weiss. She didn't recognize the sender, Joe Nagai, J-O-No-E. Inside, there was a handwritten letter, four pages long. So, shall I read you part of the letter? Please.

To Martha Weiss. Hello, nice to meet you. My name is Joe Nagai. I'm from Japan. I live in Kobe, Japan. I'm in the second grade at Ibuki Elementary School. When I found your research on the internet, I was so delighted. Two exclamation points.

Two bold exclamation points. My mom is an entomologist. She studies insects. And she gets letters from strangers pretty often. They're mostly about this one study she worked on. She and her student were studying moths, and they figured out that an adult moth could remember something it learned as a caterpillar. Even after metamorphosis, the memory carried through. It made kind of a splash.

What's your feeling like coming out of this? My feeling is wow. This is my mom on radiolab I think it's amazing that a caterpillar can have an experience Go into its chrysalis five weeks pass emerge as a Seemingly different organism and that it still can recall

Experiences that happened to it when it was a caterpillar. Freaking cool, I gotta say. There were a lot of interviews like that, and a lot of emails. But the letter my mom picked up that day at work was different from any of the fan mail she'd gotten before. For starters, the author was a kid in second grade, writing from the other side of the world. But more importantly, he was writing to tell her that he was an insect scientist himself. In the letter, Joe described his discoveries.

I've studied swallowtail butterflies for three years. In kindergarten, he'd investigated how long a swallowtail butterfly could stay alive if it got stuck in the chrysalis. In first grade, he'd found caterpillars that molt more often than usual. But now, Joe said, he was hoping to try something a lot more complicated. I've always thought that my butterflies could remember me even after their metamorphosis because they always flutter around me whenever I try to let them go into nature. But sadly, some say that's impossible and ridiculous.

I have some questions to you. Have you ever experimented in swallowtail butterflies? I want to try to find if a swallowtail butterfly could remember what it learned as a caterpillar. Joe, an eight-year-old, wanted to replicate my mom's groundbreaking experiment because he wanted to know if his butterflies could remember him. I came home and said to dad, look what I got in the mail. This was the most fun letter I ever got. Yeah, I was there when the package came.

That's my dad, Josh. Full-size sheets of paper with his handwritten letters, photos of himself. A very cute kid with glasses. And his butterflies. He's looking through magnifying glass. And then there are two pages of data figures. I mean, she was laughing and pages of data figures. I mean, she was laughing and reading with her mouth wide open. I thought it was wonderful. Joe had no idea what a perfect correspondent he'd found. Because the only audience my mom respects more than her entomological peers is small children. They are curious about stuff, and they haven't figured out that it's boring

to look at plants or bugs. She's diagnosed elementary school as the last chance to intervene before the veil of indifference descends. Seventh grade, eighth grade, is it going to be on the test? Do we have to know that? Second grade, third grade, bingo. And something horrible must happen in fifth and sixth grade. Puberty. Everybody becomes more interested in each other than the bugs, which is good because it helps our species persist.

Outside her academic work, my mom has spent decades weaseling her way into children's classrooms to make the case for the humble arthropod. She brought poop-shooting caterpillars to my kindergarten. She organized cricket races at my sister's 10th birthday party. Every year, she and her colleagues crawl around the woods collecting caterpillars to show off at schools around the city.

They call it the Caterpillar Road Show. So with Jonah Guy, my mom wasted zero time in writing him back. Dear Joe Nagai, I was so excited to get your packet in the mail. It was such a fun and interesting letter. I loved reading about your experiments and your discoveries, and I'm so happy to have a new friend in Japan who loves caterpillars and butterflies as much as I do. To be clear, she didn't actually think Jo could recreate her experiment. The way she and her grad student Doug Blackiston had done their study was by training

caterpillars to hate a specific smell and then testing whether once those caterpillars became moths they still hated the smell. They did the training with this elaborate lab setup where they'd release the chemical smell then give the caterpillar an electric shock, so it would associate the smell with pain. Not totally a kid level project. So in that first letter, my mom suggested Joe try something simpler, like teaching butterflies to learn colors. I could help you test this with your swallowtails, which might be a great research project for third grade. So here you're giving him the old, why don't you try colors before memory through metamorphosis. Exactly. I could write so much more but want to send this off now so you will know how happy I

am to have heard from you, your friend Martha Weiss. And then I included some pictures, a zebra swallowtail butterfly and an eastern tiger swallowtail just to show that we both are swallowtail aficionados. A few weeks later, she got a response. Dear Professor Martha Weiss, thank you very much for your reply. I was so happy and surprised to have a reply from you. I couldn't believe it first. Thank you very much. Jo politely expressed interest in her color-learning experiment and thanked her for the butterfly photos.

"...their blue is so beautiful and like deep ocean." But he stuck to his guns on the memory stuff. "...I really want to prove it's possible that my butterflies can remember what they learned as a caterpillar. I don't want to give up now. I really need your help." And Jo wasn't waiting for her approval. He told her he had already started adapting her protocols for his own at-home lab. But I don't have any devices in my house. I can't make electronic shocks. This wasn't what my mom had expected. The letter was so serious. Joe was so serious.

So that summer, they became regular pen pals. In his emails, Joe kept her up to date on his work. And he was confident. Like he wasn't afraid to question my mom's research methods. Why, for example, she'd chosen the chemicals she'd used to train the caterpillars. I have no idea why you picked ethyl acetate for the experiment of Manduca sexta. I felt a little bit defensive about my use of ethyl acetate. Still, in every email, Joe thanked my mom for her time and attention. I know you're so busy, but I'm so happy when you write me back. In the fall, he wrote to say his study was done.

It was 33 pages in Japanese, but he'd helpfully translated the basics. He said he'd done essentially the same study as my mom. Trained caterpillars to hate a smell, tested whether they'd avoid it as butterflies. He'd used a little muscle therapy device to give the shocks, and lavender oil instead of that toxic chemical for the smell. So the caterpillars learned to hate the lavender. And according to Joe, when those caterpillars became butterflies, 80% of them still avoided the smell.

If what Joe said was true, not only had he replicated my mom and Doug's groundbreaking experiment at home over summer vacation, but he found their same results in a whole new species. They'd studied moths, but he was the first person in the world to show that memories could persist through metamorphosis in butterflies. And what did you think when you got that email? I was flabbergasted and delighted. And in this letter, I thought, holy cow, he's a real scientist, and he's figuring out new stuff.

And he's figuring out new stuff. As the months went on, my whole family became obsessed with Joe. We talked about him all the time. You just don't expect to see or hear that level of sophistication out of anybody without a PhD. My dad again. Definitely not someone in elementary school. We go to see friends or family or something, and we're like, you gotta know, here's the latest updates on Jonah Guy.

My sister, Isabelle. What's the new T? What's he up to these days? What has he discovered? What kind of advances has he made? Every time I talk to your parents, I get the parents update and I get the Jonah guy update. My boyfriend Harrison. And there's always something exciting.

For example, in September 2022, Joe presented his research to scientists at Shinshu University, then at Tsukuba University and Saga University. He also graduated from second grade. And then in the spring of 2023, Joe wrote to my mom rather casually that he had a whole new research question. He wrote, by the way, I'd like to study if memories can be inherited to the next generation this summer. Joe wanted to study if caterpillar children could remember things that had happened to their parents. I know that most people generally think memories can't be inherited from ancestors, Joe wrote.

But he'd found a recent study that suggested it might be possible in nematodes, these tiny freaky worms. If they could do it, he thought, why not swallowtails? It had never occurred to me to even ask that question. Joe's first study was advanced, but this was a whole other realm. Epigenetics. The ways environment and experience can change how our genes are expressed, even across generations. It's a field of biology my mom calls the new frontier.

And it's not exactly her area of expertise. I don't live on the frontier. I live in the heartland. And so when he said I read the nematode paper, I had to go scramble and find the nematode paper. I was too embarrassed to ask Joe which nematode paper, because I didn't want him to be too much ahead of me on the up to the minute research.

The inheritance of memory has only been studied in a few species. Those worms, some mice. My mom wrote back to Joe, this is a controversial topic, but that doesn't mean that it doesn't happen. We can learn more by doing more studies. Joe forged ahead. He did his experiment again,

but tested a second generation too, to see if they avoided the same smell he'd trained their parents to hate. And a few months later, he wrote to my mom that the results were clear. His butterflies had passed their memories on to their children. When I was growing up, bugs were a central feature of our household. They were just always around. My mom raised silkworms in a box in the dining room, and she kept cicada exoskeletons in a jar in the kitchen, which my teenage friends found horrifying. She was waging the pro-bug campaign on the home front. And for a while, it worked.

You don't squish bugs and you don't scream when you find a spider in the bathtub. I consider that a victory. But I guess at some point, that dreaded veil of indifference fell over me too. Or maybe it was just puberty. By the time I was in high school, I was less interested in bugs and more interested in people. These days, my extracurricular reading is about stuff like historical memory, how experience moves down through time. That's what I'm always trying to report on, although my editors tend to steer me towards

the news. But now, my mom's tiny genius pen pal was saying he had proof that in this one species, what happens in a parent's early life can show up in their kid. The inheritance of traumatic memory. The caterpillar body keeps the score. My mom is always warning me against anthropomorphism. But in a way, it seemed like Joe was asking the same question I often am. How we get to be who we are. How to say butterfly in Japanese.

Cho. Oh, I know that. I knew that because Madame Butterfly. A while back, my mom got this note from Joe. He said, Dear Professor Martha Weiss, hello, how are you? Blah blah blah. Is it getting colder in your town too? How do your caterpillars and butterflies spend during cold winter? Well, do you know the International Congress of Entomology ICE 2024? The website is as follows with the URL. It will be held in Kyoto, Japan in 2024. Are you going to come and attend it? If you come there, I'd like to see you and can show you around Kyoto, Osaka, and Kobe, my town." My mom did in fact know the International

Congress of Entomology. It's one of the biggest conferences in the field. It was happening in August. She hadn't been planning on going this year, but a personal invite from Joe changed the equation. And once she decided to go, there was no question. Actually all of us would come to Japan. My entire family, plus my boyfriend, bought plane tickets. In the months leading up to the trip, my mom helped Joe with his application to present a poster at the conference. She thought he had basically a dissertation's worth of research.

She, on the other hand, was bringing a plan for an experiment she hadn't actually started yet. Maybe he can lend you one paper. Yeah, just come on. I loved the story of Joe, this child prodigy showing up my mom, esteemed entomologist. And I was telling everyone I knew about his big finding. But now we were about to actually meet him, and part of me had started to worry. Over two full years of correspondence, my mom and Joe had never actually spoken. In

fact, she wasn't even writing him directly. You're emailing his mom's email. Because he doesn't have his own email. So his mother is the invisible portal through whom we communicate. So his mother's name is Sarie. And so I get an email from Sarie and it says, Hi, this is Joe. And then I write to Sarie and say, Hi, Joe. Although two times ago I wrote and said, Hi, Sarie, this is Martha Weiss. Joe invited us to come visit him in Kobe.

And so I just wanted to check in with you. And have I heard from Sari? No. But I did hear from Joe what hotel he and his mother Sari will be staying in, in Kyoto. So I made reservations at that hotel too. Which I, I'm, I'm interested in this dynamic. Like do you feel like you need to talk to his mom? Like cause you're sort of, you're sort of emailing a child all the time?

Well I feel the science is between me and Joe. But when he says, come visit me at my home in Kobe, then I need to check with his mom. Have you ever thought about like, like zooming him? I guess I did initially, but but I don't know, there's something sort of nice about writing. It's sort of Jane Austen of you guys. A little more Jane Austen. Exactly. I think he feels that way too.

I mean, do you like the mystery? Like do you like that we just like I mean, Jonah Guy is like a is like a national hero in our house. I guess I do that way too. I mean, do you like the mystery? Like, do you like that we just like, I mean, Jonah Guy is like a, is like a national hero in our house. I mean, Yes, I do like the mystery. I think, I think that's part of it. I'm, and to be honest, I'm a tiny bit nervous about meeting him in person. What are you nervous about?

I don't know. I mean, I guess, I guess our correspondence is, it's all about science and butterflies and there's nothing else in it. Like what if he's like a mean kid who has temper tantrums and, you know, kicks and screams and bites his baby sister or, you know. Sure. You know, I can't imagine that Joe is a biter. But are you at all worried that he's a catfish? Well let me just say that I only recently learned the term catfish. And some people have said to me, is this kid for real? Do you think that this is an elaborate ploy? You're sort of a trusting correspondent.

I'm a trusting correspondent. Hey, this is Molly again. We are going to take a quick break, but when we get back, we will find out kid or catfish when Martha and her entire family go to Japan. That's coming up after break. Hey, this is Radiolab. I'm Molly Webster. And today we are playing a super special story for you

called Caterpillar Roadshow. It is about a bug scientist and a young boy in Japan who strike up a long distance email correspondence because they're both really excited about the scientific work of caterpillars, butterflies, moths. Up until this point though, they have never met in person, but that is about to change. Let's listen in. So they have never met in person, but that is about to change.

Let's listen in. Welcome to Tokyo. The local time is 2.55 in the afternoon on August 15th. Please stay comfortably seated until the seatbelt sign has been turned off. When we got to Japan, Joe still had a few days of school before the conference, so we had to find ways to distract ourselves. Which wasn't hard. We were surrounded by amazing and surprising things.

Like the public toilets that automatically make the sound of a waterfall and birds chirping to cover up any embarrassing pee noise. And the beautiful glowing vending machines on every other block. At any time of day or night, you can pop in a couple hundred yen and get a whiskey highball, or a sippy cup of apple juice, or a perfect sports drink called Pokari Sweat. But the most amazing and surprising thing? Bugs were everywhere. In the trees outside temples, restaurants, but also on t-shirts, book covers, street signs.

On the subway, we saw a poster for an insects show at the Tokyo Museum of Nature and Science. Inside, the hall was packed with hundreds of people more excited than I've ever seen anybody in a museum, honestly. And they weren't just stopping at the iridescent butterfly wings. They were reading about the way a spider disguises itself to mimic an ant. Structural color. Parasitic wasps.

You see that a lot in Japan. You go to just a public park in the center of Tokyo, and you'll see a parent with a butterfly net with their child carrying a little insect cage. This is Akito Kawahara. He's a big deal in bug science, the director of a center for butterfly and moth biodiversity in Florida. And he grew up in Tokyo. I called him to ask basically, is this a thing?

Or was I just on high alert for bug stuff? Like the bug-shaped toys we saw all over the city. So gotcha gotchas. So what it is is essentially it's a gumball machine where you put some money, a dollar or two, into a machine. One, two, three. And a ball comes out. Ready? Yep.

And inside the ball, there's a toy. You're a big boy. And there's a whole bunch of insect ones. And some of these insect ones are extremely realistic. Yeah, look how much you can make it move around. It's a deal for a articulating steel. And then look, we should get another one so it can fight. Japanese pop culture isn't just full of bugs.

It's full of youth insect enthusiasts. Akito told me about a popular video game where you play a kid helping a scientist collect and identify escaped bugs. And the guy who created Pokemon, he started out wanting to be an entomologist. The game came straight out of the years he spent scouring the wilderness for bugs. People here have been insect fans for a long time. More than a thousand years ago, Japanese nobles kept crickets in cages to listen to

their chirps. In the late 1800s, kids' magazines aggressively advertised bug collecting to patriotic and masculine boys. By the 1930s, insect-hobbyist societies had hundreds of members who'd go on collecting trips, tromping around the forest and posing with their butterfly nets like big game hunters. Beetles in particular became kind of a status symbol, an exotic pet. It got to the point where people were trying to grow the biggest beetles and then they would sell them.

In one case, one of the beetles sold for an incredible $90,000. One of Akito's closest friends actually raises beetles sold for an incredible $90,000. One of Akito's closest friends actually raises beetles. Every time I go back to Japan, he's driving a different colored Ferrari. And oftentimes I joke that I might've made the wrong decision in my career to become a scientist. And maybe I should've just reared beetles and had a life that was different from what I'm doing now.

Papillozufus, is that right? That's his butterfly. At the museum, I thought about Joe. From the distance of my mom's kitchen in DC, his passion had seemed totally unique and mysterious. Here it suddenly seemed a lot less random. We found an exhibit about swallowtails, and my mom texted Sari, Joe's mom, a picture. Sari sent back an emoji of a rabbit with exploding heart eyes.

They'd finally made direct adult-to-adult contact. She and Joe, and his brother, were coming to meet us in two days. We're on the train, finally on our way to meet Joe. I can't go through it. I'm getting off at the next station and going back in the other direction. Too late. We pull into the station, get off the train, and there they are, just on the other side of the turnstile.

I'm trying to be present for the meeting and also fumbling to get my recorder rolling. Hello! How are you? Sarie, in her late 30s, has a ponytail, a white blouse, a parasol for the sun, and then there are the two boys. Must be Harry.

Hayato, or Harry, age 13, made eighth grade growth spurt in a huge t-shirt and baseball cap. And next to him, the man himself. He's a pretty small guy, with very discreet bangs like the tines of a feathery fork, big Harry Potter glasses, and a round little face that makes him look younger than 10. He's wearing a traditional gin bay, a matching wrap-around shirt and shorts, and carrying a backpack about half his height. And you have your butterfly net. He and my mom are both smiling big, but a little awkward with each other,

like meeting somebody for a first date after you've bared your soul to them over text. For the next few hours, Joe takes the reins. As we walk around the city, he makes the most of opportunities for viewing wildlife. For example, a pigeon we pass. We can't touch it, but it is very cute. We visit Himeji Castle, Joe's favorite castle, and he points out big gulping fish swimming in the moat.

Oh. It is beautiful. Look at their blue, flashing blue. Yeah. Beautiful. Wonderful. And he helps us work on our manners. If you eat food, first you say,

itadakimasu. Itadakimasu. Itadakimasu. And, what does that mean? You say, itadakimasu. Itadakimasu? Itadakimasu. What does that mean? We eat birds and fish and a lot of creatures. So we have to thank. To say thank you.

Thank you. To say thank you to the creatures. Creatures, yeah. Thank you to the creatures. Creatures, yeah. And can you say... Joe seems to be amazed by basically every living thing we see around us. He's sweet and solicitous, and also a totally normal kid. Impatient in the heat, hungry for junk food, constantly proposing a game.

What do you do? Like, who has the stronger pine needle? So Joe's is stronger? Are you stronger than me? Yeah. At lunch, Sari tells us that Joe has been invited to present his research to the crown prince of Japan in a private meeting at the beginning of the conference. He seems unfazed. He says he's just a little nervous. But he's starstruck by my mom. When we finish eating, she presents Joe with a hand lens, a little magnifying glass attached to a ribbon,

just like the one she wears around her neck. He makes very direct eye contact and says, I love this so much. I want it. and says, I love this so much. I want it. Outside the restaurant, a woman is performing a Japanese version of Part of Your World from The Little Mermaid.

And somehow it feels exactly right. It's a million degrees out and we're soaked in sweat, all awkwardness gone, everyone is giddy. It feels like a fairy tale. Castles and princes, a sage advisor, a young apprentice. We take a bus to the edge of the city and ride a glass gondola high up into the mountains. At the top we climb out into a cool sweet-smelling forest and a symphony of bugs. What's that? It is a beetle. It is a beetle. Beetle, yeah. Do you need a case?

Yeah. Do you need a case? Um... I have a case. I don't. Yes, please. Yes, please. I made a mistake to not bring my cases with me. Yeah, Joe came prepared.

I will give you. Thank you very much. At the top of the mountain, Joe sees something. He leaps forward, his net zigzagging back and forth like a banner. And then... I get it! You got it? Nooo! I take it! Wow! Oh, that's the one you showed me!

Yeah. Ah, that is beautiful! Joe showed me a picture of this and he said we might find these. It's an East Asian tiger beetle. Maybe the most flamboyant bug I've ever seen, with a bright green head, long and tiny blue and rust-colored splotches all over its back. Oh my goodness, look at that color. It's a little shiny and a metal color.

Sarie convinces Joe to let it go. I will release it. Can I hold it for one second? The wings are... Goodbye! Good luck! He's very powerful. Yeah, he's a strong flyer. Goodbye. Good luck. He's very powerful.

Yeah, he's a strong flyer. The moon is rising over the city. We catch the last gondola down in the pink light. After dinner, my family boards the train back to our hotel. Hayato and Joe wave from the platform for a full minute. And once our train starts moving, Joe runs after it. Outside the window of the train, we just saw him speeding along and keeping up with us until our bullet train pulled away and we left him behind.

And I just felt like it was the best day ever. When I was six, a brood of periodical cicadas emerged in DC. Billions of bugs that spend their whole lives underground and tunnel up to the surface just once after 17 years. For a few chaotic weeks, the city is completely overtaken by their wine. As you might imagine, while most people saw the cicadas as a menace, my mom was basically hysterical with excitement. Late at night, the bugs would climb up trees around the neighborhood to molt.

And one night, she let me and Isabelle stay up until midnight to watch. We walked down the block with flashlights, stopping at a tree. Just above my head, these bright white cicadas with ruby red eyes were stretching backwards out of their old shells. So new to the world, they were still damp. It felt like I'd been let in on a huge secret, catching them in this private moment in the dark. I was reminded of that night walking into the conference center. Here I was an interloper again, surrounded

by thousands of entomologists, the international denizens of my mom's world. They weren't the most visually intimidating group, lots of cargo shorts and t-shirts with bug puns on them. But this was their turf. They were keepers of bug knowledge not yet released to the larger world. I was unprepared for the scene in the poster hall. Alongside the adults, there was an army of young scientists. Hello, we are from Takatsuki Senior High School. And today we would like to talk about turn-out nation of peel bags.

These were Joe's peers. At 10 years old, he wasn't even the youngest presenter. I'm Takeru Inagaki. I'm in the fourth grade of elementary school. I've been collecting bottom-right since I was six years old. Takeru was approximately three feet tall. Thank you for listening to my presentation. My research is about leaf rolling weevils.

Do you know leaf rolling weevils? No, I don't know them. Let me explain. Thank you. Shusei is 14. It's a very impressive presentation. Yes, thank you very much. Are there many students your age who are doing entomological research?

Yes, many kids, students are doing some kind of research about insects. But his one is really amazing. He was looking over at Joe, whose poster was right next door. Hasee, did he explain it to you already? Actually he's my friend. Our house is really close that we can meet each other often. And do you guys discuss your research together? Yes. He's four years younger than now.

But the things that he's doing is more level-high. Joe was in full networking mode, suit and tie, handing out his business card. I'm Joe Nagai. Nice to meet you. Nice to meet you. Nice to meet you. So, can we take a picture with you and the poster? You have a bright future in front of you, no doubt about that. Hanging around Joe's poster,

I met Masato Ono, the conference chair. President of organizing committee. Oh, wow, okay. Very nice to meet you. And Akito Kawahara, the big-name butterfly expert from earlier. He's just incredible. Like, you know, everything that he's done is just, like, incredible.

Like, I want him in my lab. I'm secretly like, oh, maybe, like, he wants to do some research in America. We stood there watching Joe together. In the parent generation, I give the electric shock and the lavender odor. I waited until they became butterflies and they avoided the ramen order. So I know they can remember what they know as caterpillar. In the 10th generation, they also avoided the ramen order

so that memories can persist to the next generation. All day, Joe and his poster were swamped. I could barely see him behind his crowd of admirers. That night, back at the comfort in Kyoto, Joe went straight to the hot tub for a triumphant soak. Conventional scientific wisdom says it's easier to remember a painful experience than a positive one. That's why in their original experiment, my mom and Doug decided to teach their caterpillars to hate a smell, shocking them every time they smelled it.

And it was clear from the caterpillar's behavior that they were receiving the shock. And I'll just leave it at that. Could you just say what that means? No. When my mom or her student pushed the button, the caterpillar would start to convulse and sometimes vomit. When Joe replicated the experiment, he'd taken a different approach.

Instead of high-voltage lab equipment, he'd used that little physical therapy device, a pad that emits small amounts of electricity to treat muscle pain. Joe already had one at home to help with pain in his own shoulders. I put the pad on my arms, and inside of that pad there is a caterpillar. So the caterpillar would be sitting literally on Joe's arm, right between the pad and the softest part of his wrist. And so did you also feel the shock when they felt it? Yes. And was it painful to you or what did it feel like to you? The first was very good for me, but if I did it every day, my arm will be red, pink or

red, so I was very pain, I have pain. The machine has a bunch of different power levels, from 1 to 15. Joe had stopped at level 4. And what was your thinking about why to use that level of shock and not more shock? Because in the level 4, they put out their osmoteria. Osmoteria, little orange horns that pop out of the caterpillar's head when it gets scared. So I think it was enough for the caterpillar. And so you didn't want to hurt them more than you needed to?

Yes. Yes, okay. In the breakfast room at the hotel, Joe got the machine out of his backpack for a demonstration. Sans' caterpillar. Okay, where do you put it on my... Here. He strapped the little pad onto my forearm and pressed the button. Is it coming?

I don't feel it yet. Is it? Oh, now I feel it a little bit. Number two. Okay, another one. Three. Whoa, I feel it. It was a crazy feeling.

A huge shudder that made my hand jump. Do you see any zospiteria coming out? that made my hand jump. The science isn't clear on whether bugs feel pain. And as my mom has explained to me, there aren't a lot of rules around how you should treat them as a researcher. So if you're going to do something with a vertebrate, you have to put in a whole animal protocol. It has to be taken care of in an approved animal care and use facility. There's committees that monitor everything. Invertebrates, nobody cares one

iota about. Hostie That means it's up to each individual scientist to set their own standards. Hostie Well, so what is your personal standard for your approach? Dr. Kirsten Kiefer That compassionate and treat them as if they feel pain and try to minimize any pain or suffering. While getting our science done. Joe seemed to have different priorities. He could have said, boy, I really want to make

sure that they get it and crank it up to nine, but he didn't do that. You're thinking of the caterpillars almost as friends, maybe. I think it's a friend. You think it's a friend? But I give the electric shock, so from the caterpillar, I am a bad friend. I talked to Joe for a long time about this. He told me he doesn't actually want to be an entomologist when he grows up.

He wants to be a veterinarian. What kind of vet do you want to be? I can fix caterpillars and insects both. Do you know of, are there other insect veterinarians now? There are no insect vets now. So you might be the first insect vet? Yes. Way back in that first letter to my mom, Joe had told her he wanted to study insect memory

because he thought his butterflies remembered him. Joe had a relationship with the bugs he worked with. And that relationship had shaped his questions, his methodology. So many scientists see anthropomorphizing as a cardinal sin. But for Joe, I realized, interspecies empathy was kind of a sleeper strength. All this work had come out of his willingness to wonder what a bug might know or feel. On the last morning of the conference, my mom said there was something we needed to do. All this time, she'd been an advisor to Joe. She'd checked his methods, helped him write his abstract, but she still hadn't seen his actual data,

the raw numbers themselves. She didn't know for sure if we could conclude with statistical certainty that his findings were true. When I stopped to think about it, it seemed crazy that we'd made it through the whole trip without looking at this. But when I said that to my mom, she surprised me. Is it going to hold up if we do a statistical test?

Are we going to see a significant result? In some ways, it doesn't really matter because a ton of other stuff has happened. And then I surprised myself because I sort of disagreed. I was still thinking about the science, this thing about memory and generations. I wanted it to be true. This is kind of what I'm trying to understand. Like, does this finding matter? Does this finding matter?

I mean, does what I do matter? At some level, yes. At some level, no. Am I curing cancer? No. Am I stopping climate change? No. Am I helping myself and other people understand how organisms work and how they interact with their environment? Yes. And will that help us maybe understand our environments and our planets better and maybe help us have a little bit more empathy for some of the organisms that we live with?

I hope so. But the other reason that it matters is because I care about Joe. Joe, who had spent five of his ten years of life on these studies and reached out to a scientist across the world to help him find answers. This was important to him. And he was important to us. And so we needed to know. Joe and Sari brought his research binder to my mom's hotel room.

Together we went through it page by page Now you know them went to the sugar water my mom asked about his controls and they double-checked his counts And then she said they needed to do a test. It's a test of probability And and it's how likely something is to happen by chance If we take our 10 yen coin and we flip it in the air, how many times are we going to get the castle and how many times are we going to get the 10? Joe looked at her for a second, a little confused. Why don't you do it for me 10 times

and tell me each time what you get. Just quickly. Okay, so you've got a 10. Joe and my mom sat at the table. 10. Sari and I on twin beds, watching them flip the coin. Paris.

In my head, I was cataloging all the little happenings that got us here. 10. Okay. That Joe found my mom's research and could understand it. That he had a mom who could and would help him do his own research. That my mom would be so willing to get on board and to rope the rest

of us in too. Five 10s, five palaces. And that is pretty much what you would expect because they're the same and half the time it's going to be one and half the time it's going to be the other, right? What if you did that and you got a 10 10 times in a row? What would you think? 10 is very heavy. That there's something a little weird going on with that coin, right? What we do first when we're doing this test is we figure out what our expectation is,

okay? And so for our first generation, we had 44 caterpillars made choices, right? We would expect if they hadn't learned anything, we would expect that 22 of them, half of them, would go to sugar, pocari sweat, and that 22 of them would go to lavender, right? And having just said how valuable the details of the science turn out to be, you don't really need to know how to do statistical analysis to understand what comes next. So we're just going to go times 2 equals 6.07. Is 6.07 smaller or larger than 3.841? Larger.

Larger. So that means that this result is very unlikely to happen just by chance. This means that something happened to those butterflies to make them make that choice. That is what we call a statistically significant result. In the months since we got back from Japan, my mom and Joe have been drafting a paper on his findings together. They're going to send it to the Journal of the Lepidopterous Society to tell them, we think this is really true.

Butterflies can remember something they learned as caterpillars, and their kids can inherit that memory too. In DC, my mom's been reading up on epigenetics. She told me she's been thinking about our conversations, remembering things from her own childhood and from when she was pregnant with me. She spent a long time in the hospital in the months before I was born,

and a student had brought her a bunch of caterpillars to keep her company next to her bed in a little plastic shoe box. And as her stomach ballooned with fetus me inside, the caterpillars crawled out of their box and into different corners of the room to pupate. As we know, lots of things are going on inside that chrysalis. So they were changing in the same way that you were changing. And then they emerged as butterflies and you emerged as a little red frog with a weak chin. Oh my god. Joe meanwhile is finessing his study on butterfly grandchild memory.

He's about to finish fifth grade. A Japanese TV station recently aired an episode about him. When he opens the door to the camera crew, MTV Cribs style, he's wearing the hand lens my mom gave him on a ribbon around his neck. That was an excerpt of Caterpillar Roadshow produced and reported by Annie Rosenthal. That story first premiered on the audio magazine Signal Hill. You can listen to the entire piece along with a bunch of other really great stories from Signal Hill and you can get that wherever you get podcasts. That's Signal Hill.

So this story had sound design and editing by Liza Yeager and Jackson Roach, who I'm proud to say are former Radiolab interns. We miss you guys. They had help on the piece from Leo Wong and Omar Etman It was fact-checked by Alan Dean special thanks to Carlos Morales John Lill Marfa Public Radio the Nagai family the Rosenthal family and Emma Garshagan for tipping us off to the story in the first place And that's it. We will be back soon with a brand new full episode of radioolab. I am Molly Webster. I got to listen this time. It was so fun listening with you.

Hi, I'm Dylan. I'm calling from the St. Lawrence River in upstate New York, and here are the staff credits. Radiolab was created by Jad Abumrod and is edited by Soren Wheeler. Lula Miller and Lata Nasr are our co-hosts. Dylan Kies is our director of sound design. Our staff includes Simon Adler, Jeremy Bloom, Becca Bresler, W. Harry Fortuna, David Gable, Maria Paz Gutierrez, Sindhu, Jnana Sambandhan, Matt Keielpe, Annie McEwen, Alex Neeson, Sara Kari, Sara Sandbach, Anissa Vista, Arion Wack, Pat Walters, and Molly Webster. Our fact checkers are Diane Kelly, Emily Krieger, and Natalie Middleton. Hi, I'm Rafael Collin from Farrotilha, Brazil. Leadership support for Radiolab's science and programming

is provided by the Gordon and Barry Moore Foundation, Science Sandbox, a Simon's Foundation initiative, and the John Templeton Foundation. Foundation support for Radiolab was provided by the Alfred P. Sloan Foundation.