
In today's podcast, we get a tantalizing taste of words in the wild, from the jungles to the prairie.
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Jad Abumrad
Wait, you're listening. Okay.
Ari Daniel Shapiro
All right.
Robert Krulwich
Okay.
Jad Abumrad
All right. You're listening to Radio Lab.
Klaus Zuberbuller
Radio Lab shorts from wnyc.
Robert Krulwich
Yes.
Listener
And npr.
Jad Abumrad
Hey, I'm Jad Abumrad.
Robert Krulwich
I'm Robert Krulwich.
Jad Abumrad
This is Radiolab, the podcast. The podcast. And in this podcast, I don't know, how would you describe this one?
Robert Krulwich
My sense is that you walk into a wild place and you hear the wind and the trees and you hear these chirps and sounds and calls and they're just part of the they're part of the wild. They're wildlife. But there is now a group of scientists who listen to much more closely and who are reducing wildlife to wild talk. There are words in there.
Jad Abumrad
When you find the words, as the people we will meet do in these stories, you end up not just understanding, but actually entering that wild space in a very cool way.
Robert Krulwich
So we're going to tell you two tales here.
Jad Abumrad
Two different places. The first a jungle and the second a prairie. Right? Jungle gets us started and then the prairie later. This is a story, this first one that we heard about.
Ari Daniel Shapiro
Yeah, yeah, from Ari. I'm Ari. Daniel Shapiro. I'm a public radio producer in Boston.
Jad Abumrad
Ari recently met a guy, I think a German guy.
Ari Daniel Shapiro
He's Swiss. Oh, okay. So, yeah, his name's Klaus Zuberbuller.
Klaus Zuberbuller
Hey, Ari. It's Klaus.
Ari Daniel Shapiro
And he's a professor of psychology at the University of St. Andrews, which is in Scotland.
Jad Abumrad
And where does this story actually take place?
Robert Krulwich
Because where's the jungle?
Jad Abumrad
Yeah.
Ari Daniel Shapiro
Well, maybe the best place to start is to kind of describe the scene where we are, which is in the Thai forest. Thai forest, which is in the Ivory coast, in Africa.
Robert Krulwich
So it's not in Thailand.
Ari Daniel Shapiro
No, it's not. It's Tai Tai. Okay. Yeah. And Klaus describes the jungle as this thick sensory world, very dark, very moist.
Klaus Zuberbuller
And very, very green.
Ari Daniel Shapiro
And you can't really see for more than 15 to 20ft.
Klaus Zuberbuller
And, I mean, sometimes you feel like you walk through a big cathedral of dark trees and you don't see very much because all the animals obviously very shy and run away.
Ari Daniel Shapiro
I mean, is it still.
Klaus Zuberbuller
No, it is very, very noisy.
Ari Daniel Shapiro
It's a din. It's just this kind of sonic chaos. Chaos.
Klaus Zuberbuller
All these insects and birds and bats and mammals. It's almost as if they compete for acoustic space. So it is very, very loud. I mean, the main sensation you have in the beginning, meaning really, is that you're just completely lost.
Ari Daniel Shapiro
So it's 1991, and they figured he had to start somewhere, so he focused his attention on a kind of monkey, very beautiful monkey, I think, called the Diana monkey.
Klaus Zuberbuller
It's a mix of black, white, and sort of reddish.
Ari Daniel Shapiro
Diana monkeys live up in the treetops, which can be as high as 100ft off the ground.
Listener
Wow.
Ari Daniel Shapiro
They eat fruits and they eat insects, and they're chattering.
Klaus Zuberbuller
Cacophony of calls.
Ari Daniel Shapiro
Which to him, of course, you know, as a newcomer to the forest, was all just noise.
Klaus Zuberbuller
It's a little bit, I imagine, like a child trying to learn a language, which initially must just sound like a string of sounds that he can't really understand. And then, you know, what.
Jad Abumrad
So what did he do?
Ari Daniel Shapiro
Well, he started provoking the monkeys into making different kinds of noises. For instance, he'd walk out into the forest with a boombox and play the sound of the Diana monkey's most feared predator, the leopard.
Jad Abumrad
He would just play the sound into the trees.
Ari Daniel Shapiro
Yep. And all of a sudden, they start leaping around the branches, hopping around.
Klaus Zuberbuller
Motion.
Ari Daniel Shapiro
And they make this one particular call.
Klaus Zuberbuller
You know, these very loud alarm calls.
Ari Daniel Shapiro
This one here.
Robert Krulwich
Meaning what?
Jad Abumrad
Yeah, Are they just saying, like, run, or is it something more specific?
Ari Daniel Shapiro
Well, here's where it gets a little bit more interesting. Next step, he brought that same cassette.
Jad Abumrad
Player out, pointed at the trees, hit play.
Ari Daniel Shapiro
All that. Yep. But this time he plays the shrieks.
Klaus Zuberbuller
Of a crowned eagle.
Jad Abumrad
Eagles eat monkeys.
Ari Daniel Shapiro
Yeah, they do.
Klaus Zuberbuller
They attack from above about them.
Robert Krulwich
They're very scary. They come flying in with their talons or their beaks, and they hit you in the head sharply and kill you instantly. And then you fall to the ground.
Ari Daniel Shapiro
Yeah.
Jad Abumrad
And so what do the monkeys do when they hear this?
Ari Daniel Shapiro
They make that sound.
Jad Abumrad
Same one.
Ari Daniel Shapiro
Well, that's what he thought. But when he went back to the lab and started looking at the sounds on the computer, comparing one to the other, eagle, leopard, eagle, leopard. He realized that they're actually slightly different.
Klaus Zuberbuller
In the acoustic details of the calls. And it's something that is very difficult to hear when you really only see it in the spectrogram, which is kind of a visual representation of these calls.
Jad Abumrad
This is on the computer?
Ari Daniel Shapiro
Yeah.
Klaus Zuberbuller
But interestingly, once you've seen that and once you know what to pay attention to, you go out into the forest and suddenly you do hear these differences, which you haven't heard before.
Robert Krulwich
So you're saying when they hear a call, leopard coming, they go up the tree, but when they hear eagle coming, they run down the tree.
Ari Daniel Shapiro
Exactly, exactly.
Robert Krulwich
So it's really kind of like a word. It's like a word that's kind of amazing.
Jad Abumrad
Let's pull out for a second. Because this guy actually got us thinking, honestly, how much language actually is out there in the wild? Like, what do we know? What's the state of what we know right now? And that question led us out of the forest just for a second, and to a place and a creature we just didn't think would be a part of this conversation at all. And that creature is the prairie dog. Prairie dogs.
Robert Krulwich
So here's the thing. Prairie dogs are these little rodent like animals. They live under the ground in burrows, and when their community is invaded, they pop out of the burrow and they say, oh, here comes the whatever.
Kahn Slobochikoff
Sounds kind of like chee chee, chee, chee, chee, chee, chee, chee.
Jad Abumrad
So we spoke with this guy.
Kahn Slobochikoff
My name is Kant Slobochikov, professor emeritus at Northern Arizona University, who spent a.
Jad Abumrad
Whole lot of time sitting out in the colonies recording prairie dog calls. And he now believes that these simple little rodents are like nature's wordsmiths.
Kahn Slobochikoff
Well, the thing is that initially I.
Jad Abumrad
Recorded, for instance, he began by telling us that the prairie dogs have different.
Kahn Slobochikoff
Kinds of cheese for different kinds of predators. For example, humans, coyotes and dogs. Right.
Jad Abumrad
Is this the kind of thing that we would actually be able to hear the difference between the calls?
Kahn Slobochikoff
I'm guessing that you could hear the difference.
Robert Krulwich
You want to try it, Chad?
Ari Daniel Shapiro
Yeah.
Jad Abumrad
Soren, could you just play those samples? All right, so here's one.
Klaus Zuberbuller
This is another one.
Jad Abumrad
All right, here you go.
Fidelity Disclaimer
This is a third.
Jad Abumrad
Those represent different predators.
Kahn Slobochikoff
Yep.
Robert Krulwich
I can't tell the difference.
Jad Abumrad
Can you? I mean, do you know what they are?
Kahn Slobochikoff
My guess is human, dog, coyote.
Jad Abumrad
Kahn was right.
Robert Krulwich
Khan was right.
Jad Abumrad
Wow.
Robert Krulwich
Well, naturally we wondered, how did he.
Jad Abumrad
How did he do that?
Robert Krulwich
Yeah, he told us that at first, just like you and I, he couldn't figure out how to distinguish between these sounds. But he took the sound back to.
Kahn Slobochikoff
The lab where we had a machine that allowed us to measure a series of frequency and time elements in the call.
Robert Krulwich
And what this computer does is it takes the sound that the prairie dogs make, and it essentially looks inside for the ingredients inside the sound.
Jad Abumrad
Yeah, like. Well, it's kind of hard to hear with a chirp because it's just hard. So let me demonstrate crudely with this other sound. I plucked this at random from my library. So this is kind of like a buzz.
Robert Krulwich
Okay.
Jad Abumrad
Okay. Let me just loop it so we can hear it better. So here you've got this buzz, which is sounds to us like a solid piece of noise. But get an EQ and take away all the highs. So now you've got just the bass.
Robert Krulwich
Yep.
Jad Abumrad
Now you'll notice that if you add the highs back in real slowly, these little hidden overtones will pop out. Like, there's one. Yeah, there's another third.
Robert Krulwich
Yep.
Jad Abumrad
Fourth.
Robert Krulwich
Uh huh.
Jad Abumrad
So in other words, this sound is filled with little ghost notes that we can't hear. And certainly the same is true of this sound. Except in the case of the prairie dogs, it seems their ears are tuned to hear all the different sounds within. The chirp probably sounds to them like.
Ari Daniel Shapiro
This whole layer cake of tones.
Robert Krulwich
And Kahn's computer noticed that the noise they made when a human walked through their village was different in tone from the noise they made when a coyote walked through their village. It was consistently different.
Kahn Slobochikoff
But there was a problem when he.
Robert Krulwich
Zoomed in on the, oh, here come the human calls. These ones here.
Jad Abumrad
And he looked at them really closely. He saw that from one human call to the next, there was a lot of subtle variation.
Kahn Slobochikoff
Much, much more than I would expect.
Robert Krulwich
And that's when it hit him, what.
Jad Abumrad
If, what if, what if?
Kahn Slobochikoff
What if they could be describing the individual humans?
Robert Krulwich
Oh.
Kahn Slobochikoff
Now, at that time, no one suspected that this might even be a possibility, but I thought, well, let's try it and see what happens.
Jad Abumrad
So Kahn recruited four humans, and he.
Robert Krulwich
Had them dress exactly the same. Same boots, same blue jeans, same sunglasses, Everything the same, except the color of their shirts.
Kahn Slobochikoff
We had person in a blue T shirt, person in a green T shirt, person in a yellow shirt, person in a gray shirt.
Jad Abumrad
Then he asked each of them to walk through the prairie dog village.
Robert Krulwich
One by one.
Jad Abumrad
Prairie dogs made their chirps.
Kahn Slobochikoff
And when we analyzed the results, there were significant differences.
Jad Abumrad
Like what kind?
Kahn Slobochikoff
They essentially clustered around the colors.
Robert Krulwich
Does that mean you think you can hear them saying, here comes the human in blue.
Kahn Slobochikoff
Right.
Robert Krulwich
Versus here comes the human in yellow.
Kahn Slobochikoff
Right.
Ari Daniel Shapiro
Really?
Kahn Slobochikoff
Oh, I was astounded. I was astounded.
Robert Krulwich
He was like, well, wait a second. These humans, they're not just different in their shirt colors. They're different in all kinds of ways.
Kahn Slobochikoff
Some of the humans were taller. Some of the humans were shorter.
Jad Abumrad
So we went back, reanalyzed the chirps, looked a little more closely, and he realized we could tease out the prairie dogs were also commenting about the general.
Kahn Slobochikoff
Size of the human. Essentially, they were saying, here comes the tall human in the blue versus here comes the short human in the yellow.
Robert Krulwich
Wow.
Jad Abumrad
And then he made another leap.
Kahn Slobochikoff
And it was just, you know, since he was on a roll off the wall idea at that time, he went.
Robert Krulwich
Back into the prairie dog field, and he built two large wooden boxes sitting.
Kahn Slobochikoff
On stilts a good distance from each other, 150ft. And we strung wires between the two towers.
Robert Krulwich
His team then made cardboard cutouts of three different shapes.
Kahn Slobochikoff
A circle, a square, and a triangle.
Robert Krulwich
And then they ran them out along the wire, kind of like laundry fluttering above you in the breeze.
Kahn Slobochikoff
Each shape would emerge from one of the tower blinds and fly something like about three feet over the prairie dog town.
Jad Abumrad
So literally, you would just kind of go, and out would come a triangle or a circle or a square.
Kahn Slobochikoff
Correct. And what we found was that the prairie dogs could tell the triangle from the circle very easily, but they could not seem to tell the difference between a square and a circle.
Robert Krulwich
Huh.
Jad Abumrad
Why not?
Kahn Slobochikoff
Well, my guess is that triangles kind of look like cocks. Circles and squares kind of look like terrestrial predators.
Jad Abumrad
Nonetheless, what you've got here is a little rodent with a remarkably big vocabulary, including, but probably not limited to short, fat, skinny, tall, blue, green, yellow, gray, coyote human Hawk, triangle and or square.
Ari Daniel Shapiro
Yay.
Jad Abumrad
Not bad.
Robert Krulwich
Is the next step that you're going to perform a scene from the Winter's Tale and see whether the prairie dogs laugh at the right moments. What do you do next?
Kahn Slobochikoff
Well, we just are scratching the surface of looking at this. For example, prairie dogs have a lot of calls which we call social chatters. One prairie dog will be feeding and suddenly lift up its head and go, chitter, chatter, chitter, chitter. And another prairie dog somewhere across the colony will lift up its head and go, chatter, chatter, chitter, chitter. But what does it mean we have no way of getting at? Could be just simply chatter, chitter, chitter. Or it could be, do you know where Sam was last night?
Robert Krulwich
Now, here's an interesting question. I mean, if a French couple were sitting next to me on the subway and they were saying, do you know where Sam was last night? In French. If I don't speak French, I'm outside of that conversation. But a lot of people do speak French and they can listen to French people talking. The question's then raised. If you live in the forest and you speak chimp or you speak eagle or you speak snake, would you ever be able to overhear or learn something from a neighborly species? In other words, is there an equivalent of listening to the other person talking French in the wild?
Jad Abumrad
Hmm, good question.
Robert Krulwich
And that brings us back to Klaus. You remember Klaus?
Jad Abumrad
Yeah, the monkey guy.
Ari Daniel Shapiro
Yeah, the monkey guy. Well, Klaus was wondering the same thing.
Jad Abumrad
And that's re Daniel Shapiro again, who introduced us to Klaus.
Ari Daniel Shapiro
So take those alarm calls for instance. He wanted to know whether different species of monkeys could understand each other.
Klaus Zuberbuller
Right.
Ari Daniel Shapiro
So, and luckily for Klaus, there's like at least 10 different primate species living inside that Thai forest. So there is one, colobus monkeys, two.
Klaus Zuberbuller
Spot nosed monkeys, three.
Ari Daniel Shapiro
Chimpanzees, four.
Klaus Zuberbuller
Galagos colobines, six.
Ari Daniel Shapiro
Honeynose monkeys, seven.
Klaus Zuberbuller
Mangabe species, eight. Pro simians, nine.
Ari Daniel Shapiro
Campbell's monkeys, and then the Dianas, 10.
Klaus Zuberbuller
Yeah. So it's a very, very rich primate fauna.
Ari Daniel Shapiro
So, Klaus, question was, could Diana monkeys understand the alarm calls of another of these monkeys, the Campbell's monkey?
Jad Abumrad
Could they go across monkey lines, so to speak?
Ari Daniel Shapiro
Exactly. So he used that same setup from.
Jad Abumrad
Before, the speaker thing where he plays the sound onto the trees.
Ari Daniel Shapiro
Yeah. And he played the eagle and leopard alarm calls from the Campbell's monkeys to the Dianas to see if they'd react.
Klaus Zuberbuller
And what we found there, to our great surprise, was that the Diana monkeys, they understand it.
Jad Abumrad
Really?
Robert Krulwich
Really.
Ari Daniel Shapiro
Yep.
Klaus Zuberbuller
They take that Very, very seriously and respond to it very strongly.
Ari Daniel Shapiro
So a Diana monkey hearing a Campbell's eagle alarm call will respond as though there were an eagle and will respond to the leopard alarm call as though there were a leopard, and vice versa.
Klaus Zuberbuller
And it doesn't stop there.
Ari Daniel Shapiro
Klaus started playing the monkey calls to birds such as hornbills, yellow casked hornbills. It turns out that they understand it, the birds.
Jad Abumrad
Yeah.
Klaus Zuberbuller
These hornbills are capable of discriminating these different monkey alarm calls.
Robert Krulwich
Wow.
Klaus Zuberbuller
So it's a pretty substantial web of species basically eavesdropping on each other's calls in these forests.
Ari Daniel Shapiro
But Klaus himself, he was still on the outside of it all.
Klaus Zuberbuller
It is that general sense of perhaps not really belonging there.
Ari Daniel Shapiro
But then he told me about this.
Klaus Zuberbuller
One day, I was working in the forest.
Ari Daniel Shapiro
He had gone out for the day, and he had gone out alone and.
Klaus Zuberbuller
Was very far away from camp.
Ari Daniel Shapiro
And it was in the late afternoon, and he realized that he should probably be heading back to camp because I.
Klaus Zuberbuller
Still had to walk for something like 15, 20 kilometers back to camp.
Ari Daniel Shapiro
And he was walking past a kind of valley.
Klaus Zuberbuller
And then I heard, on the other side of the valley, a monkey group giving leopard alarm calls, which doesn't happen that often.
Ari Daniel Shapiro
It was the first time that he wasn't actively listening, but he heard these monkeys make this call and recognized it.
Klaus Zuberbuller
He was absolutely striking.
Ari Daniel Shapiro
And he was actually quite excited by.
Klaus Zuberbuller
This because I was suddenly able to understand what the monkey's trying to say, so to speak.
Ari Daniel Shapiro
Those monkeys had picked up a leopard.
Robert Krulwich
Right beneath that sound there.
Ari Daniel Shapiro
The leopard would be right. But, you know, those monkeys were way across the valley.
Klaus Zuberbuller
So I didn't really think that much, and walked on perhaps, you know, half a mile further down the road.
Ari Daniel Shapiro
And the next group of Diana monkeys, still across the valley, started giving leopard.
Klaus Zuberbuller
Alarm clocks as well.
Ari Daniel Shapiro
And he kind of took notice of that. And then it happened a third time a few minutes later.
Klaus Zuberbuller
What became clear to me very rapidly is that a leopard was.
Ari Daniel Shapiro
Tracking him.
Klaus Zuberbuller
Of course, I couldn't see it because it was dense forest, but I assumed that the leopard saw me. And of course, that is just one of these moments where you're totally alone far, far away from camp.
Robert Krulwich
What does he do?
Ari Daniel Shapiro
He kept walking. It happened a fourth group called Leopard, fifth group called Leopard, and then the group stopped calling.
Klaus Zuberbuller
The only thing I could think of is to pick up a large branch.
Jad Abumrad
I shouldn't laugh. That's terrifying.
Ari Daniel Shapiro
Klaus, would that stick have done anything for you?
Klaus Zuberbuller
I doubt I really would have been able to do very much with a stick.
Ari Daniel Shapiro
But as he's standing there, stick in hand, he realizes he's just entered the forest.
Klaus Zuberbuller
He's become the 11th primate.
Ari Daniel Shapiro
The 11th primate because there are those 10 other species of primate. And now me.
Klaus Zuberbuller
Suddenly, I shifted from being the objective observer to being, you know, sort of part of that whole crowd in there. Even though, you know, we're separated by 20, 30 million years of evolutionary history. You know, these humble creatures, you know, were able to teach me something about, you know, what was going on in the forest. And of course, it wasn't intentional. They weren't trying to inform me or anything like that, but it was a very emotional experience.
Jad Abumrad
So what happened? I mean, obviously he didn't get an eaten. What happened?
Ari Daniel Shapiro
Well, he. He made it back to camp and he's not sure what happened to the leopard. The leopard must have slinked off into the forest. In the end, it became just another.
Klaus Zuberbuller
Story to tell each other over beers in the evening, I suppose.
Jad Abumrad
Yeah, yeah, yeah.
Robert Krulwich
Thanks for that story to Ari, Daniel.
Jad Abumrad
Shapiro, our correspondent, and also thanks to Klaus Zuberbuller and Khan Slobochikoff. I'm Jad Abumrad.
Robert Krulwich
I'm Robert Grillwood.
Jad Abumrad
Thanks for listening.
Cassandra Williard
This is Cassandra Williard, a Radiolab listener in Brooklyn, New York. Radiolab is supported in part by the Alfred P. Sloan Foundation, Enhancing public understanding of science and technology in the modern world. For more information about Sloan, go to. Let me start over. More information about Sloan@www.sloan.org. end of message.
Episode Overview
In this episode of Radiolab, hosts Jad Abumrad and Robert Krulwich embark on a journey into the world of animal communication, asking: How much language is hiding in wild animal chatter? The show investigates the “words” in nature, highlighting scientific discoveries about how creatures from monkeys in African jungles to prairie dogs on the American plains signal, warn, and perhaps even describe the world—and each other. This exploration not only questions the boundaries of human language but also the nature of communication in the wild.
[01:49 - 02:32]
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