Short Wave - Murder, Mayhem At The Zoo: A Naked Mole Rat Succession War

Episode Date: January 31, 2024

An all-out "naked mole rat war" has broken out at Smithsonian's National Zoo, after the queen of the colony was mortally wounded by one of her own children. Short Wave's Pien Huang and Margaret Cirino visit the battleground – a series of deceptively calm-looking plexiglass enclosures at the Zoo's Small Mammal House. There, the typically harmonious, eusocial rodents are now fighting their siblings with their big front teeth to determine who will become the new queen. Pien and Marge talk with zookeeper Kenton Kerns about what led to this violent succession drama, the stress he feels in witnessing his first naked mole rat war and how he hopes it will resolve. NOTE: This episode contains some detailed descriptions of animals fighting each other, so be warned. Check out the Smithsonian National Zoo's naked mole rat live cam.Pondering the implications of other monarchies and social hierarchies? Email us at [e-mail] pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

A quick note before we get started. This episode contains some detailed descriptions of animals fighting each other. There will be blood, so please be warned. You're listening to Shortwave, from NPR. Hey, shortwavers, Ping Huang and the host show today, and it's a very special day. Producer Margaret Serino and I... Hello? We bring you a story of one royal family.

And this isn't just any regular old royal family. This is, again, a species that lives undergrad in Africa, right? That's Kenton Kurtz. He's the assistant curator of the small mammal house at Smithsonian's National Zoo and Conservation Biology Institute. And he proudly told us he's been zookeeping this colony for the whole five years they've been here. Ken says there's a lot we still don't know about these guys.

They weren't really studied in depth until the 1970s. They're used social and live in a colony. They are so long-lived being, you know, over-thirty-year-old. years, they are almost cancer resistant. They are naked mole rats. Best creatures of all time. Totally agree. I mean, Marge, you know this. I'm actually a little bit obsessed with naked mole rats,

and I will use any excuse that I can get to do a naked mole rat story, including their messy family drama. We paid a visit to the small mammal house, and Ken gave us the grand tour of the castle. Starting with, as you pointed out, paying dining halls of sorts. There are 12 windows that look into different rooms. This room, a different... Then chambers for pooping.

Kind of like a five-bath, one-bed situation. You know those are hard to come by. There's a big plexiglass elevated box where they sleep in a big pile. And they're kind of like cuddled up next to each other as they feed. I don't know if they're actually like cuddling. or like pushing against each other, trying to sort of vie for the best bite. We were there early in the morning,

and most of these little boogers were still snoozing, all cuddled up. I mean, it is winter. They're effectively hairless and cold-blooded with very little fat. So they're all huddled together for warmth. It was so cute, maybe even a little peaceful. Up until recently, that observation would have matched reality. But lately, it's like a switch was flipped. We came to their clay castle in the small mammal house because of one event.

So it all happened very quickly. It was last June, and the naked mole rats were getting their monthly checkups. We're looking at, are they moving around normally, do their mouths and their teeth look good? Teeth are really important to naked mole rats? And are they acting normal when we handle them? Ken says they're basically checking to make sure that all the mole rats are healthy. They were putting all of the mole rats all 65-ish into the bin. The keepers turned around for five seconds, turned back,

and there was blood in that big tub with all the mole rats. The queen was bit. She had a gash on her back. She was bleeding profusely. And everyone else had blood on them because of the queen's wound, but we could not tell who did it. So that was our first foray into what turned into a naked mole rat war. Today on the show, naked mole rat succession,

What this bloody power struggle tells us about the tension between cooperation and the animal instinct to survive. And how a comfortable life in captivity isn't necessarily stress-free. I'm Ping Huang. I'm Margaret Serino. And you're listening to Shortwave from NPR. To understand societal upheaval, we must first understand how the colony, a naked mole rat monarchy, works. So every rat has a job that helps keep the hive going. Some of them are soldiers.

They'll go run and defend the territory and the resources from other mole rat colonies and also from predators. In nature, they've got some enemies. For these guys, it's snakes. Snakes come down, soldier mole rats will go, try to die it to death and keep it out. And they actually sacrifice themselves. So the snake won't go down and eat the queen. So the snake will fill up on soldier mole rats and then continue on. Every naked mole rat is really in it for the colony, not just themselves.

Because soldiers might never breed and are kind of genetic. Basically speaking, useless. So sometimes in the wild, they'll fall on that sword or snake. And then there are helper mole rats who will move around food, build tunnels. Occasionally, scientists have described like a nursery attendant who might move the babies around, but it's possible that's just a different role for the helpers. Now, this colony started as a small branching off from a different zoo, and from the start, it was clear that one of the mole rats was a natural queen.

And it was obvious why. She was big. She had nipple development. She was, you know, running through the tubes and pushing everyone out of her way. And that's what happened. She ruled over the colony in relative peace for the past five years. We thought she was holding her own, but obviously someone had it out for her. A hundred percent of the naked mole rats in this colony are the queen's children. They are all from her lineage. But we're not too worried about inbreeding here because, curiously,

rodents in general tend to have a high tolerance for it. They don't get a lot of genetic abnormalities when they mate with close relatives. That means that when our queen was attacked at the end of June, it was by one of her own children trying to take over the throne. In classic aristocratic fashion. And the fighting happened so quickly that no one saw what happened. All they had were a bunch of clues. We see blood smears. We see blood on maybe somebody's mouth.

We'll see blood on somebody's back. The OG queen survived that first attack, we'll call it the first battle of the rats. But then, she got attacked again and again. That final attack, the third battle of the rats, occurred November 30th. And one big bite to her back was all it took. She lost the use of her two hind legs. And a queen losing her hind legs, it was a big deal because... Typically with mole rats, they have 20% of their musculature and their jaw.

So if you think about all that musculature in their jaw, a bite is really severe. We knew we couldn't isolate her for long enough to heal her up. And after three attacks, we knew that was it. They didn't want her to be queen anymore. Okay, a moment of silence. After she lost the use of her legs, the zookeepers had to euthanize her. She was 11 years and 3 months old, which is young for a naked mole rat. Their typical lifespan is 30 years.

Though that gets cut short, especially if you're a hotly contested queen and your army of children has a penchant for violence. So yeah, it was both emotional and also really anxiety-inducing. For us, we've known her. We've seen her personality. We've seen her give birth to multiple litters, take care of tons of babies. We've worked with her to try to make it so that she can have the most successful litters possible. But we knew what would happen next, which is war. Molrat war.

It gets so much worse. The coup had finally succeeded, but the real war was only just beginning. So we prepared ourselves. As soon as the queen left this colony, we knew there would be turmoil because there's a power vacuum, right? And we know that naked mole rat colonies need a queen.

You just have to have one. All the females, we just slowly noticed higher levels of aggression. Ken told us that the wounds started getting more aggressive. They started seeing some mouthing behavior, naked mole rats clashing with their big front teeth. They started seeing cuts around some of the mole rats' mouths. Clearly, they'd been picking fights. We would come in one day and find someone on their side who'd gotten a bite overnight

and wasn't able to come back from that wound. At least eight more mole rats have died. War has been crawling along for two months, with skirmishes breaking out, and then an eerie calm. Okay, so it's been a couple months now, and what you're describing is all-out war, I have to say, looks pretty calm to my untrained eye. So tell me what you're seeing in these tubes that indicates all-out war to you, or is this kind of like, does the war kind of happen, like, quickly and burst, and we're just not seeing it right now? Yes, quickly and in bursts. This is the calm before the storm.

They lull you into this false sense of security, and we think, oh, things have been quiet, things are good, and then suddenly, will come in and we'll find blood everywhere. In fact, we had some fights last night. We have a couple mole rats this morning that are wounded. We are monitoring them closely. They all look at today. They have wounds, but they're wounds that will hopefully heal on their own. But yeah, it's very tricky.

Because right now, and this morning, everything looks okay. And so to be clear, the ones that attacked the queen, we think are female soldier mole rats that were trying to depose her so that another queen could rise. I think so. It seems like all the ones that have died with the biggest scarring have been females because the reproductive tract has been starting to develop. This part is wild.

Since the queen has died, this weird thing has started to happen, and it takes a little explaining. Usually the queen of the colony is the only one that has fully developed reproductive organs. Like, she's the only one that's capable of mating and having babies. But since the queen died, several other females in the group have basically been going through puberty, mole rat puberty. Like, they're starting to develop the ability to breed. It's not super clear why. So one hypothesis is that the queen usually goes around and spread some kind of chemical signal that suppresses this kind of development in other mole rats.

You know, she's basically asserting her crowning dominance. and that's lifted now that she's gone. Ken and the zookeepers have been looking back, trying to piece together what happened. The best guess here is that something is going on. The queen is either viewed as weak. The queen is not visiting the other females in the colony as much. She typically would do something to keep the other females

from being reproductively developed, and then she stops. Maybe she's weaker, maybe she's sicker, maybe she's spending time on something else. And so a new queen would pop up on the other side of the colony. Ken says it might play out differently in the wild. Like if a queen's colony is spread out and she can't keep all of the females around her in check, maybe one of those females would ditch her crew and start a new colony.

Some of the mole rats might not have liked her, but to Ken, she was perfect. So for five years, she was like clockwork. It was 86, 87 days. She gave birth to an average of 10 babies. So, I mean, that's a lot. At least from a breeding standpoint, she was perfect. But at the end of the day, Ken, all of us really were just observers. We have to be hands off because we don't know what's going through their brains.

We don't understand their social structure. We can't. Sometimes it feels like if we intervene, we might be supporting the wrong one. And we don't even know what that means, right? Maybe you can hear it in his voice. But the way Ken talks about these rats, it's with awe and a bit of desperation. He's tired. He wants it to be over. When a fight is complete and one of the mole rats has died, we sort of take a moment to think, okay, maybe that was it. Like maybe those were

the last two that we're fighting, and now we have a winner and she's going to become the queen. And then yesterday we saw fighting again, and we thought, okay, so not right now. Now these two have to get through something. So it's really frustrating because we would love to have a stable colony and the bloodshed to end. The blood bath over the past six months has changed how Ken sees these naked mole rats. Do you think there's, like, lessons to be learned from their social dynamics

or from the way that you observe them interacting? Like, you know, is power dangerous? You know, like, where do you go with that? Yeah, I think that's a funny question because within the past five years, I would be like, of course, you can talk about supporting each other and working as a...

a team and having a common goal and working towards it. And then something like this happens, I'm like, never mind. I don't, let's not base our lives off of naked moll rats. I think I'd rather observe. Although maybe that's it. I know if I was a mole rat, I have a feeling I'd be one of the ones who was just like hanging out, doing their own thing and in the corner avoiding the two females who are struggling for power and eventually, you know, wounding each other. Perhaps this is the truest enduring lesson of the mole rat for all the struggle and throne-grabbing, all the bloody vies for power, most of the mole rats are still just toiling away, keeping on, supporting the colony in really essential ways. Yeah, Ping, I think we're both with Ken on this one. I think I'd just be

a little soldier rat, protecting my little rat pack. Go Marge. Ping, thanks for roping me into your naked shenanigans. Of course, Marge. So much fun. Before we head out, a quick shout out to our Shortwave Plus listeners. We appreciate you and we thank you for being a subscriber. Shortwave Plus helps support our show. And if you're a regular listener, we'd love for you to join in so you can enjoy the show without sponsor interruptions. Find out more at plus.npr.org slash shortwave. This episode was produced and edited and masterfully scored by our showrunner, Rebecca Ramirez,

and fact check by Britt Hansen. Robert Rodriguez was the audio engineer. And we also got to thank Ken for this one. Much love, Ken. Much love. I'm Ping Huang. I'm Margaret Serino. And you're listening to Shortwave from NPR.