What's In A Squeak? For Naked Mole Rats ... EVERYTHING : Short Wave "Dialects" is one of those words tossed around a lot when talking about human language. They indicate where a speaker is from. But dialects aren't exclusive to humans; scientists have known for a while that whales and songbirds also show these variations in language. Today, NPR science correspondent Nell Greenfieldboyce explains research that expands that list to include naked mole rats.

Yearning for more episodes about communication between animals? Or wish we would cover something else entirely? We'd love to hear your suggestions — shortwave@npr.org.
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What's In A Squeak? For Naked Mole Rats ... EVERYTHING

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What's In A Squeak? For Naked Mole Rats ... EVERYTHING

What's In A Squeak? For Naked Mole Rats ... EVERYTHING

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  • <iframe src="https://www.npr.org/player/embed/971873781/984755177" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
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MADDIE SOFIA, BYLINE: You're listening to SHORT WAVE...

(SOUNDBITE OF MUSIC)

SOFIA: ...From NPR.

EMILY KWONG, HOST:

Hey, everybody. Emily Kwong here with reporter Nell Greenfieldboyce. Hello, Nell.

NELL GREENFIELDBOYCE, BYLINE: Hello.

KWONG: And we're here to discuss a new discovery about one of the most amazing creatures on the planet, naked mole-rats.

GREENFIELDBOYCE: I saw on Twitter somebody saying they wish they cared about anything as much as NPR cared about naked mole-rats.

KWONG: (Laughter) Wow, they really got us right. Like, naked mole-rats are beloved on the NPR Science Desk. Reporter Pien Huang first brought them to my attention. But now you're here to talk about why you're fond of them, too.

GREENFIELDBOYCE: I mean, what is not to like? They are not moles. They are not rats. They're these, like, small, almost hairless, basically sightless rodents running around underground in East Africa.

KWONG: Yeah. And in laboratories, too. Like, scientists want to understand these critters. They're cold-blooded mammals. They seem to resist certain kinds of pain and cancer, I kind of remember. And they can live an incredibly long time, so over 30 years.

GREENFIELDBOYCE: And as you know, they've also got this really, you know, fascinating social structure.

KWONG: Yeah.

GREENFIELDBOYCE: They live in colonies with dozens or hundreds of naked mole-rats. But there's this one queen who gets to have all the babies, and everybody else just, like, works for her. It's like bees or ants or, you know, something like that. Anyway, to add to NPR's rich and ceaseless reporting on the naked mole-rat, I have some exciting new research findings to share with you.

KWONG: I am ready. What are the new research findings?

GREENFIELDBOYCE: They are on the sounds that naked mole-rats make. This researcher I talked with, Alison Barker, she told me that because naked mole-rats are cold-blooded, they're usually kept in these well-insulated, little habitats.

ALISON BARKER: So the sound doesn't really travel. But if you were to open one of those glass containers or, like, lift the lid to the, you know, the chambers that we keep them in, you really can hear them.

(SOUNDBITE OF NAKED MOLE-RAT CHIRPING)

KWONG: They sound to me kind of like little baby birds, you know?

GREENFIELDBOYCE: Yeah, yeah. They're like birds. And what Alison Barker wanted to know is, you know, what are they communicating with this constant chatter? And so she started looking into that, and she realized that, actually, what mattered maybe was not just what they were saying, but how they said it. And it turns out that colonies of naked mole-rats have their own unique accents or dialects, these little variations in the sound that let one naked mole-rat listening to another know instantly whether they're part of the same group or not.

KWONG: OK, so today on the show, naked mole-rat dialects. We'll look at how they squeak to each other and why it matters for researchers who want to learn more about the basic biology of language. This is SHORT WAVE, the daily science podcast from NPR.

(SOUNDBITE OF MUSIC)

KWONG: So, Nell, I have seen naked mole-rats at the National Zoo here in D.C. I spent, like, 20 minutes just standing, watching them. They're so interesting. And when you say the word dialect, that has meaning among us humans, too. Like, the word dialect means a type of speech that shows where someone is from, right?

GREENFIELDBOYCE: Yeah, yeah. So, like, for example, there's millions of people on this planet who speak Spanish, but a person who learns Spanish while growing up in Mexico might speak it slightly differently from somebody who learned it in Spain or Central America. And if you're, like, a linguist and you know about this stuff, you could just listen to somebody and be like, oh, yeah, I know where that person grew up.

KWONG: Yeah. So when applying this word dialect to naked mole-rats, does that mean that all naked mole-rats speak a basic mole-rat language, like their equivalent of Spanish?

GREENFIELDBOYCE: Yes. I mean, Barker told me they have this basic vocabulary, and she has spent a long time trying to figure out what it is. I mean, she's been listening to all their different squeaks and calls.

(SOUNDBITE OF ARCHIVED NPR BROADCAST)

BARKER: We can say now that there's about 25 different sounds that they make.

KWONG: Wow. So many.

GREENFIELDBOYCE: Her favorite is this rare one that's known as the toilet call.

BARKER: The toilet call is just as it sounds. When the queen goes to the bathroom, or one of the breeding males, she makes a little song, which is very distinct.

(SOUNDBITE OF NAKED MOLE-RAT CHIRPING)

KWONG: Is this the toilet call?

GREENFIELDBOYCE: Yes.

KWONG: That's really cool to hear. Why does the queen do that?

GREENFIELDBOYCE: Nobody knows. I mean, a more common call, you know, one naked mole-rats make all the time, is something called the soft chirp.

(SOUNDBITE OF NAKED MOLE-RAT CHIRPING)

GREENFIELDBOYCE: And Barker says, remember; these critters can't really see as they're wandering around through their underground tunnels.

(SOUNDBITE OF ARCHIVED NPR BROADCAST)

BARKER: And so if you're a naked mole-rat and you were walking in the tunnel and you bump into another naked mole-rat, which happens quite frequently, actually, you would both emit your own soft chirp. So you can think, like, if we were walking down the street and you saw someone you knew, you would say hi. The person would say hi back. And that exchange is basically the soft chirp.

GREENFIELDBOYCE: That is the specific sort of naked mole-rat word that Barker and her colleagues really focused on. You know, they focused on the soft chirp to study it in great detail.

KWONG: OK, let's get into the study itself. What did they do?

GREENFIELDBOYCE: So she works at the Max Delbruck Center for Molecular Medicine in Berlin. And they have a bunch of mole-rat colonies there that live in separate habitats. So what the researchers did was record more than 36,000 examples of soft chirps from 166 naked mole-rats living in seven colonies.

KWONG: Nell, that is so many recordings. That's essentially like a naked mole-rat recording library.

GREENFIELDBOYCE: So three years of their lives went into this. The scientists also analyzed these chirps with computers. And what they found is that each colony's soft chirp has a slightly distinct sound. I'm going to play you a few of them.

KWONG: OK.

GREENFIELDBOYCE: You know, the naked mole-rat colonies in their lab are all named after groups in "Game Of Thrones," OK? So here's the Arryn Colony...

(SOUNDBITE OF NAKED MOLE-RAT CHIRPING)

GREENFIELDBOYCE: ...And the Dothraki Colony...

(SOUNDBITE OF NAKED MOLE-RAT CHIRPING)

GREENFIELDBOYCE: ...And the Martell Colony.

(SOUNDBITE OF NAKED MOLE-RAT CHIRPING)

KWONG: I love this. This is amazing. And listening to these, I think I hear a difference, but I can't really tell.

GREENFIELDBOYCE: Well, you've only heard, you know, a couple of them.

KWONG: Yeah.

GREENFIELDBOYCE: And also, you're not a naked mole-rat, you know?

KWONG: True.

GREENFIELDBOYCE: Believe me. The naked mole-rats could definitely tell. If the researchers played a soft chirp to a naked mole-rat, it would generally only respond if it was a chirp from its own colony.

KWONG: So do they think that these dialects are a way for naked mole-rats to basically distinguish members of their own colony?

GREENFIELDBOYCE: Yeah. Yeah, that's the idea. And, you know, hearing a soft chirp that sounded kind of funny in those dark underground tunnels could start some serious "Game Of Thrones"-style conflict because naked mole-rats will do battle with other naked mole-rat groups.

KWONG: Oh, so the dialects are also a way for naked mole-rats to figure out who's not in their community.

GREENFIELDBOYCE: Yeah. So remember; these critters can live in really dry, harsh conditions, you know, like looking around for plant roots underground. And it may be that their social structure helps them eke out an existence. You know, they'll share with their buddies, but if strangers come by and start to threaten their resources, they will attack.

Now, the question is, are they born knowing these dialects or do they learn them? And it turns out naked mole-rat colonies will take in babies from other colonies sometimes. Like, if you put one in - like, if the researchers transfer a baby from one colony to another, they'll adopt them. And, in fact, sometimes they deliberately steal babies from other colonies.

KWONG: Oh, that's kind of terrifying.

GREENFIELDBOYCE: Yeah. So Barker and her colleagues showed that if babies are taken from one colony and raised in another, they will speak with the dialect in their adoptive home. So that means this is learned.

The researchers also found that in colonies where a queen dies, there's this period of anarchy as females are competing to see who will be the new queen. And when all that chaos is happening, the sound of the colony's soft chirp becomes more variable until they finally get a new queen who establishes herself and starts breeding.

KWONG: That's super interesting. So in that period of anarchy, are they all trying to sound like the new queen?

GREENFIELDBOYCE: I asked Gary Lewin that. He's another member of the research team. And he says it's not like the rodents are trying to imitate the queen.

GARY LEWIN: It's more that the presence of the queen makes everybody speak with the same voice in the sense that everybody adopts the same kind of accent.

KWONG: I see. That sounds almost like a way for the queen to control the group or create some kind of social cohesion.

GREENFIELDBOYCE: It definitely would make it clear who's in and who's out.

KWONG: The queen's dialect - that's so interesting. Now, humans obviously have dialects, but naked mole-rats we now know have them, too. Do scientists know of other animals that do?

GREENFIELDBOYCE: There are a few examples, like whales, songbirds. But what's unique about naked mole-rats is that it's a little mammal that can be studied in the lab.

KWONG: Totally. I mean, in addition to learning about their unique physical traits and their longevity, I guess naked mole-rats present this opportunity to study language, too.

GREENFIELDBOYCE: Potentially. I talked to Rochelle Buffenstein. She has thousands of naked mole-rats in her lab at Calico Life Sciences, where she studies aging. And she told me that now there's basically a rodent model of language acquisition.

(SOUNDBITE OF ARCHIVED NPR BROADCAST)

ROCHELLE BUFFENSTEIN: To me, it appears that naked mole-rats are clearly able to learn vocalizations in much the same way that humans and songbirds do...

KWONG: Wow.

(SOUNDBITE OF ARCHIVED NPR BROADCAST)

BUFFENSTEIN: ...And create this language through vocal mimicry, which is unheard of in other rodents.

GREENFIELDBOYCE: You know, it's been hard to study language and language learning in the lab because, you know, like, you're not going to do a biological experiment on a whale, you know, and same with human babies. You've got songbirds that can live in a lab, but those are birds. They're not mammals. And, you know, it remains to be seen exactly what scientists studying language do with naked mole-rats. But here you've got, for the first time, a small rodent that's been shown to use key features of language.

And, you know, I talked with one naked mole-rat researcher who was super jealous of the study. He wished he had done it. And he thinks this is going to be a game-changer because you could, for example, potentially study genes related to language difficulties.

KWONG: There are so many possibilities with this. And as far as I'm concerned, this is just one more reason to appreciate naked mole-rats...

GREENFIELDBOYCE: Indeed.

KWONG: ...And continue the coverage at NPR. So we will have to have you back on the show to talk about what's going on with the toilet call once researchers figure that out.

GREENFIELDBOYCE: And you know they will. You know they will figure it out. There is no stopping science.

(SOUNDBITE OF MUSIC)

KWONG: This episode was produced by Rebecca Ramirez and edited by Gisele Grayson and fact-checked by Rasha Aridi. I'm Emily Kwong.

GREENFIELDBOYCE: I'm Nell Greenfieldboyce.

KWONG: And you're listening to SHORT WAVE, the daily science podcast from NPR.

(SOUNDBITE OF MUSIC)

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