Radiolab - Wild Talk

Episode Date: October 18, 2010

In today's podcast, we get a tantalizing taste of words in the wild, from the jungles to the prairie.

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The podcast. The podcast. And in this podcast, I don't know. How would you describe this one? 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 wild. They're wild life.

But there's now a group of scientists who listen much more closely and who are reducing wildlife to wild talk. Yeah. There are words in there. 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. So we're going to tell you two tales here. Two different places.

The first, a jungle and the second. A prairie. Right. Jungle gets started and then the prairie later. This is a story, this first one, that we heard about. Yeah, yeah. From Ari. I'm Ari Daniel Shapiro.

I'm a public radio producer in Boston. And Ari recently met a guy. I think a German guy. He's Swiss. No. So yeah, his name's Klaus Zuberbooler. Hey, all right, it's Klaus. And he's a professor of psychology.

The University of St. Andrews. Which is in Scotland. And where does the story actually take place? Where's the jungle? Yeah. 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. So it's not in Thailand?

No, it's not. It's T-A-I. T-A-I. Okay. Yeah. And Klaus describes the jungle as this thick sensory world. Very dark, very moist, and very, very green. And you can't really see for more than 15 to 20 feet.

And, I mean, sometimes you feel like you walk through, you know, a big cathedral of dark trees and you don't see very much because all the animals obviously very shy and run away. I mean, is it still? No, it is very, very noisy. It's a din. It's just a din. this kind of sonic chaos. 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 really is that you're just completely lost. So it's 1991, and he figured he had to start somewhere, so he focused his attention on a kind of monkey. A very beautiful monkey, I think, called the Diana monkey. This mix of black, white, and sort of reddish.

Diana monkeys live up in the treetops, which can be as high as 100 feet off the ground. Wow. They eat fruits and they eat insects, and they're chattering. Cacophony of calls. Which, to him, of course, as a newcomer to the forest, was all just noise. 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. So what did he do? 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. He would just play the sound into the trees. Yep. And all of a sudden, they start leaping around the branches, hopping around, motion. And they make this one particular call. You know, this very loud alarm calls. This one here.

Meaning what? Yeah, are they just saying, like, run? Or is it something more specific? Well, here's where it gets a little bit more interesting. Next step, he brought that same cassette player out, pointed out as the trees hit play all that. Yep, but this time he plays... The shrieks of...

The crowned eagle. Eagles eat monkeys? Yeah, they do. They attack from above. I've heard about them. 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.

Yeah. And so what do the monkeys do when they hear this? They make that sound. Same one? 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. 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. This is on the computer? Yeah.

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. 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? Exactly, exactly. So it's really kind of like a word. It's like a word. Well, that's kind of amazing.

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.

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, you know, pop out of the burrow. And they say, uh-oh. Here comes the... Whatever. Sounds kind of like,

Chi, Chi, Chi, Chi. Chee, Chi, Chi. So we spoke with this guy. My name is Kanslabachikov, Professor Emeritus at Northern Arizona University. Who's spent a 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 word smith. Well, the thing is that initially I recorded... For instance, he began by telling us that the prairie dogs have different kinds of cheese. For different kinds of predators. For example. Humans, coyotes, and dogs.

Right. Is this the kind of thing that we would actually be able to hear the difference between the calls? I'm guessing that you could hear the difference. You want to try it, Chad? Yeah. So, can you just play those samples? All right, so here's one. This is another one.

All right. Okay. Here you go. This is a third. Those represent different predators? Yep. I can't tell the difference. Can you? I mean, do you know what they are?

My guess is human dog coyote. Con was right. Khan was right? Wow. Well, naturally, we wondered how did he do that? 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 the lab, where we had a machine that allowed us to measure a series of frequency and time elements in the call. 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. 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. Okay. Okay. Let me just loop it so we can hear it better. So here you've got this buzz, which sounds to us like a soft. A solid piece of noise, but get an EQ and take away all the highs. So now you've got just the bass. Yeah.

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. Uh-huh. Third? Yep. Fourth?

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 this whole layer cake of tones. And Khan'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. But there was a problem. When he zoomed in on the, uh-oh, here come the human calls. He was here. And he looked at them really closely. He saw that from one human call to the next, there was a lot of subtle variation. Much, much more than I would expect. And that's when it hit him.

What if? What if? What if they could be describing the individual humans. 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. So, Khan recruited four humans. And he had them dress exactly the same. Same boots, same blue jeans, same sunglasses, everything the same except the color of their shirts.

We had a person in a blue t-shirt, person in a green t-shirt, person in a yellow shirt, person in a gray shirt. Then he asked each of them to walk through the Prairie Dog Village. One by one. Prairie dogs made their chirps. And when we analyzed the results, there were significant differences. Like, what kind? They essentially clustered around the colors. Does that mean you think you can hear them saying,

here comes the human in blue? Right. Versus here comes the human in yellow? Right. Really? Oh, I was astounded. I was astounded. He was like, oh, wait a second.

These humans, they're not just different in their shirt colors. They're different in all kinds of ways. Some of the humans were taller. Some of the humans were shorter. 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 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. Wow. And then he made another leaf. And it was just... You know, since he was on a roll.

Off the wall idea at that time. He went back into the prairie dogfield and he built two large wooden boxes sitting on stilts. A good distance from each other. 150 feet, and we strung wires between the two towers. His team then made cardboard cutouts of three different shapes. A circle, a square, and a triangle.

And then they ran them out along the wire, kind of like laundry fluttering above you in the breeze. Each shape would emerge from one of the tower blinds and fly something like about three feet over the prairie dog town. So literally you would just kind of go and out would come a triangle or a circle or a square? 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 a difference between a square and a circle. Huh. Why not?

Well, my guess is that triangles kind of look like cocks. Circles and squares kind of look like terrestrial. predators. Nonetheless, what you've got here is a little rodent with a remarkably big vocabulary, including probably not limited to short, fat, skinny, tall, blue, green, yellow, gray, coyote, human, hawk triangle, and or square. Yay. It's not bad. 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? Well, we just are scratching the surface of looking at this. For example, So 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 it. It could be just simply chatter, chitter, chitter, chitter, or it could be, do you know where Sam was last night? 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 questions 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 name? neighborly species. In other words, is there an equivalent of listening to the other person talking French in the wild? Good question. And that brings us back to Klaus. You remember Klaus? Yeah, the monkey guy. Well, Klaus was wondering the same thing. And that's R.E. Daniel Schaberowler again, who introduced us to Klaus. So take those alarm calls, for instance. He wanted to know whether different species of monkeys could understand each other.

Right. So... And luckily for Klaus, there's like at least 10 different primate species living inside that Thai forest. So there's... One. Colobus monkeys. Two. Spot-nosed monkey. Three.

Chimpanzees. Four. Galagos. Five. Collabines. Six. Puddy nose monkeys. Seven.

Mangabee species. Eight. Pro simians. Nine. Campbell's monkey. And then the Diana's. Ten. Yeah.

So it's a very, very rich primate fauna. So Klaus's question was, could Diana monkeys understand the alarm calls of another one of these monkeys? the Campbell's monkey. Could they go across monkey lines, so to speak? Exactly. So he used that same setup from before. The speaker thing where he plays the sound under the trees? Yeah, and he played the eagle and leopard alarm calls

from the Campbell's monkeys to the Dianas to see if they'd react. And what we found there, to our great surprise, was that the Diana monkeys... They understand it. Really? Really? Yep. They take it very, very seriously and responded very strongly.

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. And it doesn't stop there. Klaus started playing the monkey calls to birds. Such as hornbills.

Yellow-cast hornbills? It turns out that... They understand it. The birds? Yeah, these hornbills... ...are capable of discriminating these different monkey alarm calls. Wow.

So it's a pretty substantial web species is basically eavesdropping on each other's calls in these forests. But Klaus himself, he was still on the outside of it all. It is that general sense of perhaps not really belonging there. But then... He told me about this one day. I was working in the forest. He had gone out for the day, and he had gone out alone.

And it was very far away from camp. And it was in the late afternoon, and he realized that he should probably be heading back to camp. Because I still had to walk for, you know, something like 15, 20 kilometers to back to camp. And he was walking past a kind of valley. And then I heard on the other side of the valley a monkey group giving leopard alarm calls, which doesn't happen that often. It was the first time that he wasn't actively listening,

but he heard these monkeys make this call and recognized it. He was absolutely striking. And he was actually quite excited by this. Because I was suddenly able to understand what the monkeys, trying to say, so to speak. Those monkeys had picked up a leopard. Right beneath that sound, there the leopard would be. Right. But, you know, those monkeys were way across the valley.

So I didn't really think that much and walked on. Perhaps, you know, half a mile further down the road. And the next group of Diana monkeys, still across the valley, started giving leopard alarm calls as well. And he kind of took notice of that. And then it happened a third time a few minutes later. What became clear to me very rapidly is that a leopard was tracking him. Of course, I couldn't see it because he was, you know, dense horse.

But I assumed that the leopard saw me. And of course, that, you know, it's just one of these moments where you're, you know, you're totally alone far, far away from camp. What does he do? He kept walking. it happened a fourth group called Leopard, fifth group called Leopard, and then the group stopped calling.

The only thing I could think of is to pick up, you know, a large branch. I shouldn't laugh. That's as terrifying. Klaus, would that stick have done anything for you? I doubt I really would have been able to do very much with a stick. But as he's standing there, stick in hand, he realizes. He's just entered the forest. He's become... The 11th primate.

The 11th primate. Because there are those 10 other species of primate, and now... Me. Suddenly, I shifted from being the objective observer to being sort of part of that whole crowd in there. Even though we're separated by 20, 30 million, of 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, I mean, of course, it wasn't intentional. They weren't trying to inform me or anything like that. But it was a very emotional experience. So what happened? I mean, obviously he didn't get eaten.

What happened? Well, 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 story to tell each other over beers in the evening, I suppose. Yeah. Yeah.

Yeah. Thanks for that story to Ari Daniel Shapiro, our correspondent. And also thanks to Klaus Zuberbuehler and Kanslabachakov. I'm Chad Abumrad. I'm Robert Grohlwood. Thanks for listening. This is Cassandra Williard, a radio lab listener in Brooklyn, New York. Radio Lab 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 at www.sloan.org. End of message.