Season 5: Episode 8

The Queen’s English

Living together in a group is a strategy many animals use to survive and thrive. And a big part of what makes that living situation successful is listening. In this episode, we explore the collaborative world of the naked mole-rat.

Guests

Credits

Transcript

[00:00] INTRODUCTION

AMY: This season, we’re tracing the story of the sounds of life on our planet, starting way back in time, with microbes quietly burbling away, slowly pumping oxygen into our oceans and atmosphere for a couple of billion years.

Until finally, complex life began to emerge. Soft, sensitive little corals. Surprisingly chatty fish. Marine arthropods, and their intrepid land-exploring brethren. 

CRICKETS

AMY: And all manner of plants, evolving in collaboration with animals, listening—and even talking—in their ways.

INSECT BUZZES and PLANT CLICKS

AMY: Throughout all of these changes, the continents were drifting around, merging and breaking up, until they smashed together into one big glob—the supercontinent of Pangea. If we could listen to an audio postcard from Pangea some two-hundred fifty-two million years ago, we would hear the voices of reptiles, amphibians, and our very distant proto-mammal ancestors, as they grew large and likely, quite loud.*

POSTCARD FROM PANGEA

AMY: And then we would hear it all

go

Silent.

AMY: It was the Permian Extinction. The deadliest event our planet has ever known.

AMY: It’s called the Great Dying, and it was caused by runaway heating. Giant cracks formed in Pangea's crust, and filled with rivers of boiling lava. Massive amounts of carbon dioxide pulsed into the atmosphere, triggering spikes of planetary fever that robbed the ocean of oxygen. Fish and corals were left gasping for breath. Almost nothing in the sea survived.

AMY: Terrestrial plants and animals did a little better, but in just sixty thousand years, around 90% of all species on Earth were wiped out. Pangea was nearly empty, and very very quiet.

AMY: Dramatically warming the planet was catastrophic. And yes, that should freak us out.

AMY: But life is determined. It took hundreds of thousands of years, but slowly, the Earth began again. Ginkgos and many conifer trees made it through and went on to flourish. New species of amphibians emerged. And one group of reptiles evolved into fearsome beasts that came to dominate the terrestrial realm. 

DINOS

AMY: Dinosaurs emerged and took center stage, owning the role of the big and the scary, while our ancient mammalian ancestors scuttled into the shadows, and perfected the arts of the small and the stealthy.

ANCIENT MINI MAMMALS

AMY: Some became nocturnal, others sheltered underground, or built homes high up in the trees. And they became excellent listeners. This was when mammalian ears and jaw bones rearranged themselves into the highly sensitive eardrums with three tiny little mallets that we still have today. This keen hearing helped them to stay alert to the many threats that surrounded them. But it also helped them tune in to each other. Because some mammals survived the age of the dinosaurs by living in cooperative groups: an incredibly powerful adaptation with listening at its core.

AMY: Welcome to Threshold, I’m Amy Martin, and after seven episodes and several billion years of Earth history, we’re finally ready to meet our first terrestrial mammal. It’s an odd little creature—a rodent that lives underground in a big community burrow. But like many mammals, including us humans, its survival depends on building stable, mutually supportive groups— societies that only work when members are listening to each other.

[05:14] SEGMENT A

AMY: I’m following Dr. Alison Barker through the hallways of the Max Planck Institute for Brain Research in Frankfurt, Germany.

LAB DOOR OPENING

AMY: She unlocks the door to a small darkened room and hands me a lab coat, hair net, and face mask to put on. There are some mysterious tubes and wires, and lots of other science-y stuff around…

AMY: And then there are these two big containers that look almost like incubators, and here's the mole-rats! Oh my gosh, somebody's like snoozing here!

ALISON: Yeah, I think it's nap time, so they've not yet been fed.

AMY: Alison and I are standing over a colony of naked mole-rats. Small burrowing rodents that live in east Africa.

AMY: I just have to get down here and look at these. They're, like, mouse-size, but with little snouts. They look like little mini pigs with long teeth attached to mouse bodies.

AMY: Except they don't look much like pigs other than in the snout, and they lack the big round ears of mice. Honestly, I'm avoiding saying what they really look like...the best description of their appearance I've heard came from the fabulous Australian journalist Ann Jones, who called them “tallywackers with teeth.”

ALISON: You know, when you first look at them, yeah, they may not be the cutest and they may not, you know, they may not have a lot of a lot of things going for them. But they really just have a lot of, I, a lot of pep, I think a lot of personality.

AMY: Naked mole-rats are not moles, or rats. They're more closely related to guinea pigs and porcupines. They have around a hundred highly sensitive hairs on their finger-sized bodies, but other than that, they are mostly naked. And they are very good singers.

AMY: I'm just sticking the microphone down into their little tunnel network. 

NAKED MOLE-RATS CHIRPING

AMY: Oh wow!

NAKED MOLE-RATS CHIRPING

AMY: They're, like, talking nonstop.

ALISON: Yeah. I wish I knew what they were saying.

AMY: Alison leads a team of researchers here who are working on figuring that out. They’ve installed an array of microphones so they can record naked mole-rat conversation twenty-four seven. In other words, this burrow is bugged.

NAKED MOLE-RATS CHIRPING

ALISON: They kind of self-designate chambers for different activities. So here this kind of, messed up area is, is where we usually feed them. And so they keep that as the dining room or the food chamber. And they generally like to sleep together in one giant pile, and so they'll have a sleeping, chamber. And they have one chamber, which actually is pretty clean today, but in the back there, this is the toilet chamber. And so they all go to the bathroom, or urinate, defecate in the same chamber.

AMY: There are currently eight separate colonies here, each with their own Lord of the Rings- themed name. And watching the 18 members of Colony Baggins, I see what Alison means about the pep. Almost all them are in nearly constant motion, busily scurrying about in their labyrinth of plastic tunnels.

AMY: Back in this back chamber there's paper all wadded up. Do they like to play in that or…?

ALISON: Yeah, so you have found the Schlafzimmer, or the sleeping chamber. So we give them fresh paper towels every day, and they like to rip them up and kind of move them around. And generally they move a lot of them into the sleeping chamber. Since in the wild, they're, they have dirt to dig through, we try and give them, you know, something new to dig through every day to kind of give them, something to organize and, keep, keep them active.

AMY: Scientists don't know for sure when mammals first started living in underground groups like this, but it appears to be a very old behavior. At one site in Montana, researchers found several skeletons of little chipmunk-like things, nestling together in a burrow beneath a dinosaur nesting area. And it’s highly likely that these little creatures were chattering with each other about where to find food, or calling out warnings when they heard hungry dinosaurs on the move, topside. Naked mole-rats emerged long after the dinosaurs were gone, but watching them move about the burrow, it’s easy to imagine how group living and acoustic communication evolved together in mammals. For one thing, traffic flow in the burrow is a constant issue. Tunnels are only wide enough for one naked mole-rat at a time, so when they meet up, they have to decide how to proceed. They negotiate this through touch, scent, and sound.

ALISON: When they approach each other in these tunnels, you can see they kind of nuzzle each other and then the more dominant individual will climb over the subordinate one.

AMY: OK.

ALISON: And so if you watch it long enough, you can usually identify the queen because she will be the one climbing over everybody else.

AMY: The queen, Her Naked Mole-rat Highness, is the all-powerful ruler here. These animals organize themselves kind of like bees or ants do—with a queen at the center, and every other member of the colony fulfilling a specific role, like foraging for food, caring for the pups, or fighting off intruders. The queen chooses a few males to be her consorts, and she's the only one who gives birth. It's called a eusocial system, and naked mole-rats and their close cousins are the only mammals known to live this way.

ALISON: And we're trying to understand how, the colony dynamics occur naturally. So who's interacting with who? We're really interested in how the queen shapes the dynamics of the colony. So, is she the first one to get food? Does she hang out more with the breeding males? Do the workers hang out with each other?

AMY: And one of the primary tools they use to negotiate all of these relationships is sound.

AMY: Oh! And Alison just pulled one out. Oh, hi!

NAKED MOLE-RAT: CHIRP

ALISON: You can hear a few soft chirps.

NAKED MOLE-RAT: CHIRP

AMY: I have to say it seems like you have a tenderness for them.

ALISON: Oh!

AMY: Does it feel that way?

ALISON: Yeah, I, I would say I have a genuine affection for these animals. I think it's really hard not to when you meet them. They're very gentle. I mean, everyone in the lab takes turns feeding them on the weekends, and I also take a turn. I like to come in on the weekends sometimes and just, yeah, see what they're up to, give them some sweet potatoes. It's really, it's really very relaxing for me.

AMY: Alison tucks the naked mole-rats back in, and we head to her office to continue our conversation. She tells me her first encounter with naked mole-rats was in Berlin, when she was interviewing for a research position. The scientist she was meeting with took her down to the basement of his building and introduced her to his naked mole-rat colony.

ALISON: And when I saw them, I basically just fell in love.

AMY: (laughter)

ALISON: For me, it wasn't really love at first sight. Although that's not to say that I don't think they're very adorable. It was more, love at first sound.

AMY: Someone happened to be feeding them right when she visited, so their enclosure was open.

ALISON: And you could hear them chirping, and they really sounded like birds.

NAKED MOLE-RATS: CHIRP CHIRP CHIRP

ALISON: There was a brief moment of sensory disconnect where you hear a sound and you think it should be coming from something else based on your whole life experience, and then you realize it's coming from this unusual-looking creature that you've never seen before. I think it was just, yeah, complete surprise. It was a real moment of wonderment, which, I don't know, becomes increasingly rare, I think, in your adult life and especially when you're on job interviews. 

NAKED MOLE-RATS: CHIRP CHIRP CHIRP

AMY: This might be the point at which you're wondering: why did a scientist in Berlin have a colony of naked mole-rats in his basement in the first place? Well, in addition to their unique eusocial system, these little critters have a surprising collection of superpowers of scientific interest. They rarely develop cancer, they have a very high tolerance for pain and low-oxygen environments, and they can live for 30 years or even longer sometimes—they're the longest-lived rodents in the world. Even more interesting, they usually stay very healthy well into old age, and the queen doesn't appear to go through menopause. There are actually way too many extraordinary facts about naked mole-rats to list here, but I can’t resist throwing in just one more: they can move their giant front teeth independently. With party tricks like that, maybe it’s not all that surprising that the sonic world of naked mole-rats hadn’t attracted much attention until Alison came along.

ALISON: When you think of all these cool things, many which have really clear clinical applications, most people would just say, “and they seem to make a lot of noises, but, you know, we're focusing on all these other cool things.”

AMY: But as a neuroscientist with a special interest in vocal communication and how it relates to cooperation, the sounds of the naked mole-rats were a siren song. Here was a long-lived species that was highly social, cooperative, and vocal.

ALISON: You know, if you watch them for a while, you see that they're constantly interacting with each other. And just the fact that they were vocalizing so much, I mean, both my brain and my heart were kind of screaming together like, you have to study this.

AMY: Living together in mutually supportive groups is a survival strategy that's evolved again and again. And sound is frequently a big part of making that work—especially among mammals. Dolphins, elephants, bats, and many other species—including us humans of course—are all highly social animals that communicate a lot through sound. And although we’ve added all sorts of elaborate layers to that process, it likely all started with the same core need: cooperating. Telling each other where to find food, or that there's a snake hiding in the grass somewhere. Listening to each other is a huge evolutionary advantage.

ALISON: So very basic, very essential things that are necessary to survive in many cases, they're enhanced when you have more information, when you can share information with the group.

AMY: In the early 1990s, some researchers started to make the first naked mole dictionary based on observations in the field. They identified 17 different sounds—and gave them evocative names like the scream, the hiss, and the toilet call.

ALISON: So we used that as a basis, and we started listening to the mole rats.

AMY: Listening—and recording. Alison and her team have captured thousands of hours of sounds, and they've now expanded the naked mole-rat dictionary to more than 25 sound types. Some of them, like that toilet call, are used only by the queen and her consorts. Alison says that make this sound when they urinate. Why they do this is one of the many mysteries of mole-rat communication. The sound that Alison has researched the most is called the “soft chirp.” All naked mole-rats use it a lot. The majority of the sounds I heard when I was observing the colony earlier were soft chirps.

SOFT CHIRPS

AMY: Alison believes these sounds communicate something about individual identity and group membership. But she also says there's a lot we don't know. The sounds could have something akin to emotional information baked into them, or location, like, “I was just here, and I'm on my way over there.”

SOFT CHIRPS

AMY: We also don't know how the naked mole-rats are using these sounds to transmit information. It could be something about the pitch, or the volume, or even the rhythm—the spaces between chirps.

ALISON: Something as simple as the Morse code, which is a series of dots and, long pulses, can give you a ton of information. And so, you know, also binary code is just, you know, ones and zeros and that can encode tons of information if you have the right, decoder on the other end.

AMY: But the only way to fully decode the soft chirp or any other naked mole-rat sounds is to pair them with behaviors. And several years ago, Alison ended up witnessing behaviors she never wanted to see, but which ended leading to one of her most important discoveries.

AMY: We’ll have more after this short break.

Break

[18:24] SEGMENT B

AMY: Welcome back to Threshold, I’m Amy Martin and Dr. Alison Barker is telling me about one of the worst things she’s ever witnessed in naked mole society. It was Christmas. Most people were on break. She went in to take care of the colony. But instead of happy little rodents nibbling on sweet potatoes, she found blood.

ALISON: We saw in one colony, the loss of a queen from a coup. So there was another female that rose up in collaboration with some males in the colony, and they attacked the queen, and disposed her.

AMY: Like, killed her.

ALISON: Yeah, killed her. It was quite, ah...I had volunteered that year to stay over the Christmas holidays and take care of the animals. And so, you know, I went in and then I kind of witnessed part of this happening, and it was very traumatic for me, especially because I was so attached to these animals. But of course, this is a natural part of their behavior. And so I just kind of had to observe.

AMY: Regicide. The queen was murdered. Soon, another queen was installed. But then it happened again. Another bloody coup. And another queen rose to power. It was a shocking amount of regime change over a very short period of time.

ALISON: A queen can be stable for decades. I mean, if she's a good queen. And ideally, that's what you would like for the health of the colony.

AMY: So this was not a situation that Alison would ever have instigated, or wished for. But she kept the recorders rolling, and when it was all over, she realized she had some remarkable data: many hours of recordings of naked mole-rat communication in two very different states of being. There was a period of stability, with a monarch in full control. And then a period of chaos, confusion, and conflict. And then another round of both.

ALISON: So, Queen Period One, Queen Period Two, Anarchy One, Anarchy Two.

AMY: And that made it possible to ask a new question: how or if the communication in the colony changed when a queen was deposed. To most human ears, there was no obvious difference. But Alison trained a computer to sort through the sounds, and soon, something fascinating began to emerge. When the monarchy was stable...

ALISON: ...everyone was basically sounding the same, or very similar. 

AMY: But when the queen was gone…

ALISON: Individuals would change their vocalizations in different ways. And so we realized when the queen is there, every individual is shaping their soft chirp so that it sounds very similar.

ALISON: The presence of the queen adds this cohesion to the colony.

AMY: So part of what makes a naked mole-rat colony work—what makes it possible for them to cooperate well—is listening to each other. Taking cues from the queen, they unify their communication, and this seems to help them understand themselves to be a consolidated group with shared goals.

MUSIC

ALISON: Each colony has their own specific dialect that they use. And when the queen disappears, this dialect falls apart and the whole colony structure becomes disorganized.

AMY: As the communication among the naked mole-rats begins to fall apart, other aspects of their society disintegrate too.

ALISON: We do find that these queenless colonies, they tend to get a bit fatter and they tend to be a bit messier. You know, you see very clearly the distinction of a well-kept colony where, you know, all the bathrooms are clean, all the food is distributed.

AMY: So what's going on here? Is this a story of a unifying leader—a queen who inspires all the mole-rats to get along, clean their rooms, and harmonize their communication? Or is it that she's more of a tyrant who tightly restricts the colony, even going so far as to censor their speech to bring them all in line?

ALISON: Yeah, there's a lot of debate about whether the queen is a benevolent figure or someone who's, you know, sort of ruling with an iron fist, let's say.

AMY: Alison says we need a lot more information before we can answer these kinds of questions. Most likely, we're not going to be able to pigeonhole the queen so neatly into one box or another. Naked mole-rats may not be large, but they do contain multitudes. And they seem to think as a multitude as well.

ALISON: Every member of the society seems to have an awareness of one another, and they really work together, to accomplish what they need to accomplish.

AMY: Could they be as cooperative if they didn't have the vocal communication?

ALISON: Yeah. I'll take a strong position on this. And I think no. The cooperation that has evolved in these animals has evolved hand-in-hand with their ability to communicate.

AMY: In order to cooperate, you need to know who you're cooperating with, and what your role is. Who's in the group, and how you fit into it. So when a naked mole-rat queen is deposed, and a unified dialect starts to fall away, it's a big deal.

AMY: Are they losing their ability to understand each other? Or is it more like everybody's trying to assert: do my dialect! No, do my dialect?

ALISON: Well, I think that's...maybe those things go hand in hand. I mean, if you're actively trying to promote your own agenda, you're not listening.

AMY: Finding the balance between talking and listening. Navigating the tensions between social harmony and freedom of expression. We tend to think of these as very human conundrums. But here they are, alive and well in naked mole-rat society too.

ALISON: You know, many species, including humans, we've been given a set of environmental conditions and we've needed to find ways to be successful with those conditions. And I think for humans, language and cooperation are some of the features that really helped move us forward and helps us be successful. And there is some value in, kind of, understanding different mechanisms that evolved.

AMY: It’s probably unwise to look to “tallywackers with teeth” for solutions to our human problems, but maybe they can help us understand them a little better. Our increasingly fragmented public discourse, the weirdly addictive vitriol on our social media platforms, the dysfunction in our democratic institutions—our modern dramas have ancient roots. We are social animals whose fates are linked together, and that means we have to figure out how to communicate and cooperate. We don’t have a choice. Just like for these weird little rodents, our survival depends on it.

AMY: Before we end this episode, I want to give a shout-out to another group of animals that survived the Permian Extinction. Or even better, let them shout for themselves.

FROG SOUNDS

AMY: Along with some reptiles and mammals, amphibians made it through that bottleneck and went on to thrive. And sound has always been a huge part of their lives.

FROG SOUNDS

AMY: But frogs, toads, and other amphibians are in serious trouble. Forty percent of species worldwide are threatened with extinction right now. Later this season, we’re going to learn more about this, and celebrate our amphibian friends—but we need your help. We’re hoping to feature the voices of amphibians from every continent where they live, which is all of the continents, except Antarctica. Depending on where you live there could be some amphibians calling in your world right now.

AMY: So what we’re asking for. We want you to go out, listen for frogs and toads, and record them. Just find someone croaking, and hit record on your phone. It doesn’t matter if there’s background noise. It doesn’t even matter if you’re not sure whether or not you’re hearing an amphibian—if you think you are, we would love to get a recording from you.

AMY: Please also say your name and where you are in the world, and then email the recording to us at outreach at thresholdpodcast dot org. Again, that’s outreach at thresholdpodcast dot org.

AMY: Operation Frog Sound: engage!

Credits

AMY: This episode of Threshold was written, reported, and produced by me, Amy Martin, with help from Erika Janik and Sam Moore. Music by Todd Sickafoose. Post-production by Alan Douches. Fact checking by Sam Moore. Special thanks to Alison Barker and Julian Burger for the naked mole-rat recordings, which were made at the Max Planck Institute for Brain Research in Frankfurt and at the Lewin Lab which is part of the Max Delbrück Center for Molecular Medicine in Berlin. Additional thanks to Tim Lamont and Lilach Hadany. This show is made by Auricle Productions, a non-profit organization powered by listener donations. Deneen Wiske is our executive director. You can find more about our show at thresholdpodcast.org.

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