The Builders

0:00Radio Lab is brought to you by Progressive Insurance. Do you ever think about switching insurance companies to see if you can save some cash? Progressive makes it easy to see if you can save when you bundle your home and auto policies. Try it at Progressive.com. Progressive Casualty Insurance Company and Affiliates. Potential savings will vary. Not available in all states.

0:21Hey, it's Latif. Earth Day is coming up on April 22nd. And so this week, I wanted to bring you a story that is just a wholehearted celebration of nature from Radio Lab spinoff, Terrestrials. We released it last fall in the Radio Lab for Kids feed. But look, I am a card-carrying grown-up. And I really enjoyed this one. And I think you will, too, no matter how young or old you are. Lulu will tell you more in a second.

0:51So without further ado. Wait, you're listening. Okay? All right. Okay? All right. You're listening to Radio Lab. For Kids! Radio Lab. From WNYC. See? Yeah.

1:14Three, two, one. Imagine. You wake up in the dark. Your eyes dart around to see a little circle of blue, shimmering light. You waddle over on your webbed feet and realize it's water. So you dive in, head first. As you kick and glide, you grow fur. Really thick fur. And an extra set of eyelids. That act like goggles underwater. And then you look behind you to find...

1:44A big, black, scaly paddle. It's your tail, which you can slap on the water with a nice, loud... You have become... A beaver.

1:58Okay, now is the part where I make you sing the theme song with me. Okay, I'm ready.

2:03Terrestrials, terrestrials. We are not the worst. We are the... First. Try again. Opposite of worst is... The best. Best real. Yeah, you got it. Okay, I like it. Terrestrials is a show where we uncover the strangeness waiting right here on Earth. I am your host, Lulu Miller, joined as always by my song bud... Take me to the river. Alan. Swimming with the beaver. So here we are, kicking off this brand new season of terrestrials. While all around us, really hard things are going on.

2:38Wildfires, wars, climate change. And so we wanted, in this moment, to look to creatures that might give us hope. Creatures that actually mend the world around them. And there is maybe no mammal that has such an outsized positive effect on the planet than beavers. Yep, those buck-toothed, waddling, funny-looking rodents. By the end of the episode, you will see how a single family of beavers can have such a positive impact on the world around them,

3:14you can literally see it from space.

3:21So our story today is going to center around one little beaver named Jose. He will rise out of murky waters in a place where no one expected he could survive. And to tell us his tale is producer bud, Ana. Yup, that's me. Yeah, you know, Jose is this incredible symbol. And here to help me is Ben Goldfarb, who's a writer. And beaver believer. Don't stop be-ve-lievin'. So Jose, he waddles out into the world with little webbed feet and whiskers and very large buck teeth that are bright orange.

3:59Because apparently... Beavers' teeth actually contain iron. Whoa, metal teeth? Yeah. Like a chisel. The iron makes their teeth excellent for chopping down trees. Because beavers have one single obsessive hobby. It's not drawing or knitting or doing puzzles. The classic beaver behavior that most people know about is they build dams. A dam is basically a wall in the water that beavers build by dragging the trees that they chomp down across a flowing stream, blocking the water.

4:32And sometimes adding mud or other stuff to keep that wall sealed up tight. When you see them sometimes carrying rocks around and their little front paws waddling on their hind legs, it's like the cutest thing ever. A beaver dam makes water accumulate behind the barricade, turning a trickling stream into a new pond in the middle of the forest. Ah, time for a stream. Ana, can I just interrupt to ask why? Like, I've always wondered this about beavers. Like, a beaver like Jose, why is it driven to go through all this work to chop down trees and make a wall that creates pools?

5:06It just feels so random? That's a great question there. I mean, a beaver out on land is basically a fat, slow package of meat. Think about wolves and mountain lions and bears and coyotes. All of those big animals are going to want to eat a beaver. According to Ben, it all stems from the fact that beavers are super awkward on land. With their webbed feet and huge tail that drags on the ground, beavers are not good at running, making them easy pickings for land predators.

5:39So, if you're a beaver, you want to spend as little time on land as possible.

5:48So... By making dams, they create deep pools of water, which allows them to transform from wobbly wolf snacks into elegant professional swimmers. Who can spin and twirl and... Can hold their breath for up to 15 minutes. 15 minutes? Yeah. They're like a magical animal. Yeah, they're just incredible. Pretty epic hiding place. Now, hundreds of years ago, in the time of Jose's great-great-great-great-great-great-great-great-great-great-grandparents,

6:19the woods of North America was full of beavers. There were probably several hundred million beavers. Making dams and ponds everywhere, even in New York City. There would have been beavers all over New York City. That's right. The Big Apple was once... The Beaver City.

6:38And the beavers of Beaver City would wake up every evening... That's right, beavers are mostly nocturnal. ...in their beaver homes and hit the road. Or the stream, I guess. And get to work. Hey, I'm waddling here! Hauling stones and sticks and redirecting water, and finishing off each day with a nightcap of sweet wood juice.

6:59Manhattan Island was one of the most lush, incredible ecosystems on the eastern seaboard. And beavers were part of what made it that way. But about 400 years ago, all of that would change. Because of the arrival of Europeans. And their insatiable desire for... Hats. Hats? Top hats and cockpats. Trapper hats with ear flaps. Wellingtons and sugarloafs. That's another name for witch hats. Made of beaver fur. Sorry, guys.

7:30They killed them off by the millions for the fur trade. And as the beavers began to be killed off, the land and waterways began to change. Pretty dramatically. Like, take the river that slides through the northern part of New York City, winding beside train tracks and beneath highways today. It's called the Bronx River. It was described as an open sewer. That's Christian Murphy. He works on the Bronx River today. It was really just an elongated landfill. And over the centuries, more and more animals disappeared from the river,

8:01including the few remaining beavers. And by the 1970s... Parents told their kids, Don't go down there. It's not safe. Because for decades, companies all along the river used it as a convenient dump for their waste. And people had just given up on the Bronx River. They thought it was just too polluted to care about. In many places, you couldn't see the water because of how thick the trash was. Until one day, someone said, You know what? This river does not need to look like this.

8:32This river could be beautiful. This river could be full of life. Inspired in part by the first Earth Day in 1970, a couple of folks from the neighborhood, like a lady named Ruth and a guy named Fred, they put on gloves and boots and began picking up the trash. Bag by bag, day by day. And at first, people kind of laughed. They thought, What good is a couple of bags of trash going to do? This whole river's polluted. But then some kids joined in. Let's do this! High five! Scooping out trash by the huge garbage bag full.

9:04And eventually, someone very powerful joined in, too. Hello, hello. A congressman. His name was Jose Serrano. With a big, friendly smile and a bigger, bushy mustache. Let's roll up our sleeves and start to clean. Who directed millions of dollars to the cleanup project. Ordering in trucks with big cranes, to fish out refrigerators and cars, and helping to change the rules over where factories could dump their toxic waste. And soon, The river began to respond. The water got cleaner. And the forest began to regrow around it,

9:36bringing in more bugs and birds. Until, a little creature popped its whiskered head out of the water. And it was a beaver. Jose! After an absence of more than 200 years, the beaver has come back to New York City. And so they named him Jose in honor of that congressman, who'd been an early beaver lever that a little awkward human effort could make a big difference.

10:10What an honor! And the fact that Jose the beaver showed up in the Bronx River wasn't just a sign that the water was getting cleaner. Because beavers clean the river too, just by being there and being beavers. See, there's a hidden power to beaver dams. They actually make everything around them healthier. And that happens in a few different ways. So first, there's the water. The dams act like purifiers that filter out pollution, like trash and even

10:41chemicals from agriculture, which get trapped in the dam and drop down into the soil instead of getting carried out to sea. Second, dams cool the air.

10:54Because the pools that dams create mean more water is being evaporated into the air. And so when it's hot, it's kind of like a mini air conditioning unit. Making it more hospitable to all kinds of creatures. Third, dams enrich the soil. Nutrients in the water get stuck and drop down into the earth, which creates more fertile ground. And fourth, the real biggie. All of this combined allows new life to sprout. Algaes, grasses,

11:25cattails, and flowers, which attract baby trout and salmon. And dragonflies and butterflies. And frogs and salamanders. And then birds come. Woodpeckers and herons. And pretty soon, coyotes and foxes. And in some regions, moose will come down there to eat all of the aquatic vegetation growing in the ponds. Thank you, beavs! And in Jose's case, after just a few years of him hanging out in the Bronx River. Somebody looked and

11:55squinted their eyes and said, wait a minute, there's a second beaver there. There are two beavers. Sacre beaver! Another beaver! And so Jose and the second beaver, they were roommates. Classic New Yorkers. Sharing rent on the river, sharing groceries, you know, cutting down the same trees together. And it gets better. I can't imagine it getting any better. But it does. Because you've maybe heard of a little-known pop star named Justin Bieber. Well, they held a naming contest,

12:26and... And the second beaver was named Justin Bieber. Beaver, beaver, beaver, oh! There's gonna be one less lonely beaver.

12:40Thank you, Alan. Jose and Justin lived together for years, munching on wood, swimming with their eyes, peeking out of the water, and slowly but surely increasing the biodiversity of the river and the forest around it. And as time has ticked on, the river has only grown healthier, welcoming back snapping turtles and sunfish, and even, as was spotted in 2023, two dolphins swimming around in the Bronx River. No. Yes.

13:12Dolphins? Uh-huh. Yep.

13:18Okay. Go, beavers. I can, I mean, imagine if, like, everywhere you walked, you just sprouted flowers and life followed you. That would be nuts. I mean, how long does it actually take? Like, once a dam goes in, is it years before you start seeing this greening effect? No, that's the thing. It's super fast. Like, within a couple of months, there'll be cattails and lily pads and swamp roses blooming. Wow. Okay, so just to recap everything these funky little guys

13:49are doing to the world around them. Their dams are cleaning the water, cooling the air, making the soil richer, and increasing biodiversity in these pretty dramatic ways. Yep. But that's it, right? Like, there's no, there can't be anything else. Oh, there's so much more. Our next storyteller thinks beavers can even fight fire.

14:13Find out how after this break. Radio Lab is supported by Capital One. With no fees or minimums on checking accounts, it's no wonder that Capital One Bank Guy is so passionate about banking with Capital One. If he were here, he wouldn't just tell you about no fees or minimums. He'd also talk about how Capital One Cafes are open seven days a week to assist with your banking needs. Yep. Even on weekends.

14:43It's pretty much all he talks about. In a good way. What's in your wallet? Terms apply. See CapitalOne.com slash Bank Guy. Capital One N-A member FDIC.

14:54Hi, Lulu here, and this episode is sponsored by BetterHelp. May is Mental Health Awareness Month, and as someone who reports on mental health, who likes talking to people about their mental health, and what they look to in science, in the natural world, in faith, in friendship, wherever it may be to help guide them through the rough patches of life, I just wanted to take a moment to say what seems to help people turn corners, find relief, get out of ruts, and even flourish is having someone with you.

15:24As much as we can feel private about our mental health struggles, you do not have to go it alone. So this May, why not treat your mental health to a buddy? And who better to talk to than a fully licensed mental health therapist? With over 30,000 therapists available, BetterHelp has someone you can talk to available at pretty much any time that's convenient for you at the push of a button. And because finding the help you need often depends on the therapist-client vibe, rest assured, with BetterHelp, you can switch providers at any time. Remember, truly, your mental health matters, and you don't have to go it alone.

15:56Find the support you need any time with BetterHelp. Sign up and get 10% off at betterhelp.com slash radiolab. That's betterhelp.com slash radiolab.

16:09Radiolab is supported by AT&T. Summer is great for many reasons. The best reason, our plans we made finally making it out of the group chat because there's more time to fit everyone in. Whatever you've got in store this summer, capturing those memories is a must. And AT&T has your summer essential in the iPhone 17 Pro. Its center stage front camera auto-adjusts the frame to fit everyone into group selfies. You don't even have to turn your phone. No awkward cropping or asking strangers to take it. Just the perfect group selfie every time. And AT&T makes sharing

16:40those moments with everyone easy because you got to share the pic or it didn't happen, right? Right now at AT&T, ask how you can get an iPhone 17 Pro on them with eligible iPhone trade-in any condition. Requires trade-in of iPhone 15 Plus or higher excluding iPhone 16E and 17E. Requires eligible plan. Terms and restrictions apply. Subject to change. Visit AT&T.com slash iPhone or visit an AT&T store for details. WNYC Studios is supported by Odoo. When you buy business software

17:10from lots of vendors, the costs add up and it gets complicated and confusing. Odoo solves this. It's a single company that sells a suite of enterprise apps that handles everything from accounting to inventory to sales. Odoo is all connected on a single platform in a simple and affordable way. You can save money without missing out on the features you need. Check out Odoo at O-D-O-O dot com. That's O-D-O-O dot com.

17:39Look! Up in the sky! It's a bird! It's a plane! No! It's beavers parachuting down from the clouds? Crates full of beavers. Part of a shipment to be dropped from an airplane. No! This is not an old-fashioned cartoon. It's something that our governments actually did in the 1940s and 50s. Some folks in a couple of different states put them in boxes and then dropped those boxes out of airplanes with parachutes on them and let them land in the mountains to do good for us, like move them from the cities to the mountains.

18:10You're kidding right now, right? They literally pushed them out of planes. Idaho did this. California did this. This is Dr. Emily Fairfax and she explains that this was the government's weird idea for pest control. They took beavers that were being nuisances, turning people's yards and farmlands to swamps, and then just dropped them off in the mountains. They are live trapped and moved to distant mountain lakes and streams where their efforts will aid to conserve water, provide fishing pools. Instead of like taking them out on a horseback or a car,

18:41they dropped them out of planes, but you know, I give them credit for trying. Now into the air and down they swing, down to the ground near a stream or a lake.

18:51Emily gives them credit because she too is trying to bring more beavers out into the wild, where they might be able to do some good for the planet. Although that did not used to be her job, far from it. She used to be an engineer who worked on weapons. Weapons! Nuclear weapons. Whoa. Very different career path. But she happened to turn on the TV one night and catch a nature documentary. And they were showing all these aerial shots of beaver dams and wetlands in the desert and they were bright green and I was like, what? Beavers live in the desert? How can they keep it green when everything's

19:23so dry? And she realized that just like her, beavers were engineers. Using all of their engineering to live a good life. And mend the world around them. And I wanted that for myself, so I started studying beavers and I haven't looked back since. Emily hung up her nuclear weapons coat and put on some rubber overalls for a new job following beavers through wetlands to try to learn how they do what they do. And eventually she came to focus on this one little family of beavers

19:53that lived up high in a mountain in Northern California in a creek. It's called Little Last Chance Creek. So she called the family the Little Last Chance Beavers. There was a mom, a dad, and? There were definitely three to four babies there. Aww. And she started watching them literally taking notes as they Timber! Constructed their intricate dams and lodges. We're logging a busy day at work. And she discovered that on really hot sweaty days inside a beaver's house. It's cold in there. You've been

20:23in a beaver lodge? I have. And on super cold days outside it's super toasty. So the beavers sleep in a big snuggle pile in like one room. It's very sweet. That's really sweet. They kind of snore sometimes. It's extremely cute.

20:39And Emily learned that their family members weren't the only ones staying warm in there. They might have mice that want to come live inside the lodge with them. They might have muskrats that want to live inside the lodge with them. They might have little snakes that want to live inside the lodge with them. They allow this? They allow these trespassers? Oh, absolutely. It's kind of like they're running a little bed and breakfast, which I call a bee and beef. It's one of my horrible jokes. winter turned to spring, spring to summer,

21:11and then one day there was a spark and the dry grasslands and forests around the Little Last Chance beaver family caught fire. It began burning and burning. It was a really devastating fire. It burned a lot of forests. This was back in the summer of 2021 and it became one of those mega fires we're seeing more and more of because of climate change. Thousands of people had to be evacuated, hundreds of houses burnt down. And as for the plants and critters of the mountains? It seems like absolutely everything has burned.

21:42By October, humans were finally able to extinguish the fire. But Emily had no idea what happened to those beavers. Could they have survived the fire? So one day, she began the long drive up the mountain. And the drive up is very disheartening because everything is just blackened. And it's silent.

22:05Which was the creepiest and strangest part to me.

22:09So I'm not feeling like super confident. But she keeps driving. And we find a route in. They get out of the car and begin walking. And suddenly, it is loud. It is splashing water. There's all sorts of birds. There's lots of bugs. There's a lot of wind in the trees and the grasses and the rustling you expect. Oh, wait. And even there being wind in the trees means there's still trees standing. There's still trees. The pine trees that were near it are fine. The trees that are in the wetland are fine. It was completely

22:40green. Completely unburnt. Not even just like a little burnt. Like, they were unburnt. And when I got there, like, honestly, it was like tears in my eyes. Why tears? Because I drove past the burned houses coming up and the burned roads and all the things that we wanted to protect and couldn't. And thinking about the future of climate change and knowing that this is the future that's coming, that's a really

23:10difficult reality to wrap your head around. I was living in California at the time. Like, I was seeing my future there. And then getting up to the beaver wetland, it was a very hopeful moment because sometimes it feels like we're all out of ideas and it's not working. But then right in front of me, something is clearly working. And even if we don't know exactly why or how yet, we can learn from it.

23:36And as for the little last chance beavers? I did stay out in the evening and saw both mom and dad swimming. And when they were out swimming, I could hear three, maybe four different young beaver winds coming from where the lodge was.

23:54They made it. Yeah. And it wasn't just them. When Emily looked at the area from way high up in space from a satellite, she saw something incredible. This halo of green around the beaver's dams. She guessed that this one little family, these five or six awkward beings had saved about seven and a half acres of land from burning. Yeah, that effect is called making fire refugia. It's a patch that doesn't burn that other

24:25things can use. Refugia is a fancy word sort of like for refuge. It's just like place that is safe. Okay. Exactly. Refugia. I love this word. I have not stopped thinking about it since Emily taught it to me. How might we all create a little refuge around us for the other beings of this world, even if we are clumsy and awkward and waddling and tired? I think about the people in the Bronx,

24:55those first two or three people who started picking up trash and eventually created a ripple effect that cleaned up the river. These things can happen, they do happen in the human world and in the animal world. That day at the beaver dam, Emily saw frogs and birds and even a bear, creatures she suspects might not have survived the fire without that beaver family. And that's why she has come to see beavers as firefighters.

25:27Yeah, they're spreading water out across the whole landscape that's keeping everything nice and green and healthy and stopping it from being easy to burn. Emily has tested this effect in mountains and forests and deserts. And so far what we've seen is that they are really good at making fireproof patches pretty much everywhere. Little rings of green that you can literally see from space.

25:53You know, when we talk about restoring nature, we don't always know how to do that. But guess what? Beavers instinctively know what it's supposed to look like. That's Beaver Believer Ben again. He and Emily both work in different ways to inspire and convince people to protect beavers. One of the mantras of the Beaver Believer goes, let the rodent do the work. They'll store water for us, they'll capture pollution, they'll help us fight wildfires, they'll create habitat for all

26:24of the fish we like to eat and the birds we like to watch and so on. And they do all of this stuff for us if we let them. Another mantra, be more beaver. What if we too worked to build structures that actually mended instead of harmed the land? As pie in the sky or impossible as that may seem, there are people already out there doing just that, following in the beaver's footsteps,

26:54waddling awkwardly toward a better world, one step at a time. Beaver Believer Beaver Believer Beaver Believer I'm a beaver believer, beaver, beaver, oh oh oh oh You little overachiever I'm a beaver believer, beaver, beaver, we see the ripple effect, you make a big splash. I'm a beaver believer, beaver,

27:25beaver, let's get to work if you believe roll up your sleeves and let me see that tail slap we're small and awkward and the challenge is tough if we work together we can rise above we waddle on until the job is done so don't cry us a river you know we'll just damn it up I'm a beaver believer, beaver,

27:56beaver oh oh oh oh you little overachiever I'm a beaver believer, beaver, beaver let's get to work if you believe roll up your sleeves and let me see that tail slap beaver, believer even though they're kinda weird the beaver's got it going on those little awkward engineers sometimes it only takes just one maybe two just a few little critters to chew what needs to be done and change the world for

28:26everyone beaver, beaver, beaver, beaver, beaver, beaver, beaver, Alan gofer and ski gofinski everybody he used real beaver tail slaps as percussion in that and that's it there's nothing else cool about to have it what's that excuse me I have a question me two me three me four the badgers listeners with badgering questions

28:57for our experts are you ready? absolutely hi my name is Felix and I'm six years old do baby beavers have baby teeth? yep not the big buck teeth but some of the side teeth which are called cheek teeth cheek teeth cheek teeth cheek teeth say that ten times fast my name is Remy and I'm six years old since beavers eat wood what does their poop look like?

29:28well they do the double poop the double poop what does that mean? they poop once and then what? they eat that again and then when it comes out it looks like a sawdust marshmallow