Like Humans, These Ants Can Perform Leg Amputations To Save Lives

This episode explores the remarkable behavior of ants performing therapeutic amputations to save the lives of their colony mates.

1. Ants perform therapeutic amputations to save injured colony mates.
2. This behavior has likely evolved as a survival strategy, enhancing the overall success of the colony.
3. Amputations are selective, based on the location and severity of the injury, akin to clinical evaluations.
4. Ants employ antimicrobial secretions, similar to antibiotics, to treat wounds.
5. The episode underscores the complex social structures and adaptive behaviors in animal species that often go unnoticed.

1: Introduction

Emily Kwong introduces the topic and guests, setting the stage for a discussion on the medical capabilities of ants. Emily Kwong: "You're listening to Short Wave from NPR."

2: Ant Medical Practices

Exploration of the types of medical interventions ants engage in, focusing on amputation and its benefits. Nell Greenfield Boyce: "Ants will treat certain injuries with therapeutic amputation."

3: Discovery of Ant Amputations

Details on how researchers discovered ants' ability to amputate and the evolutionary reasons behind it. Eric Frank: "We saw them again participating in hunts the next day."

4: Mechanism of Amputation

A look at how ants perform amputations without modern surgical tools, focusing on their natural tools and methods. Nell Greenfield Boyce: "An injured ant... will present that leg to a nest mate."

5: Impact and Implications

Discussion on the broader implications of these findings for understanding animal behavior and evolutionary biology. Daniel Kronauer: "They've basically evolved... to react to different kind of injuries in a certain way."

1. Observe and respect wildlife: Understanding complex behaviors in animals like ants can increase appreciation for biodiversity.
2. Encourage natural habitats in your backyard to observe such phenomena.
3. Teach children about the complexities of animal behaviors to foster a deeper connection with nature.
4. Support and participate in local wildlife conservation efforts to protect species that demonstrate unique adaptive strategies.
5. Engage with community science projects to help gather data on local wildlife and contribute to scientific research.

Some ants herd aphids. Some farm fungi. And now, scientists have realized that when an ant injures its leg, it sometimes will turn to a buddy to perform a lifesaving limb amputation. Not only that — some ants have probably been amputating limbs longer than humans! Today, thanks to the reporting of ant enthusiast and science correspondent Nell Greenfieldboyce, we behold the medical prowess of the ant.

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Emily Kwong, Nell Greenfield Boyce, Eric Frank, Daniel Kronauer

Content Warnings:

None

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Emily Kwong
You're listening to short wave from NPR.

Hey, short wavers. Emily Kwong here we humans, we have incredibly sophisticated kinds of medical care. Other animals not so much like. Researchers have seen evidence that some sick animals will self medicate by eating clay or certain plants.

But there is one creature in the animal kingdom who takes the practice of medicine, air quotes medicine to a whole different level. And that, my friends, is the tiny.

Nell Greenfield Boyce
Ant, which really should not surprise us, right? I mean, ants are amazing. I mean, some ants farm.

They farm fungi for their food. They herd aphids. I mean, if they've got agriculture, why not medicine?

Emily Kwong
Number one ant enthusiast and science correspondent Nell Greenfield. Boys.

Nell Greenfield Boyce
Hey there, Nell.

Emily Kwong
We wanted to have you on the show because you recently reported on one aspect of ant medical care that is truly mind blowing, at least for me, even if you're not surprised about it.

Nell Greenfield Boyce
That's right. I was kind of surprised about this, actually, despite my admiration for ant's many abilities. So there's this new research out showing that ants will treat certain injuries with therapeutic amputation.

Emily Kwong
Amputation. Just for comparison, how long have humans used amputation as a medical treatment?

Nell Greenfield Boyce
So if you look at evidence, like in the archaeological record, you can find ancient human skeletons with clear amputations that go back, like, over 30,000 years. So a long time. But the ants have probably been doing it for longer, much longer than us. And these aren't like super rare ants or anything. These are like common carpenter ants you can find in people's backyards in places like Florida.

Emily Kwong
So in someone's backyard right now, a tiny ant surgeon is effectively practicing civil war era medicine, aka amputation.

Nell Greenfield Boyce
Yeah. And I mean, the civil War medicine thing is a pretty good analogy because ants engage in battles and warfare. I mean, they hunt, they defend their territory. And that means when ants come home, back to the nest, they can be injured. And it turns out their nest mates take care of their wounded warriors. I mean, lab experiments show that their medical efforts, including, now we know amputations are very often life saving. And it turns out the ants are selective about when they perform amputations. They're not just, like, hacking off injured legs willy nilly.

Emily Kwong
All right. Well, today on the show, we dive into the anthill to check out their healthcare system. How scientists discovered that ants will perform medical acts that include clinical amputations and how the ants determine whether or not an injured limb has got to go. You're listening to shortwave, the science podcast from NPR.

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Emily Kwong
Npr okay, Nell, so how did scientists learn that ants will sometimes treat an injury with amputation?

Nell Greenfield Boyce
So the lead researcher who did this work is named Eric Frank, and he's now at the University of Wurzburg in Germany, and he's really a tropical biologist. So years ago, he was studying some ants in Africa that will hunt and eat termites. And I talked to him back then, and he told me that ant scouts would go out and find a termite nest, and then hundreds of ants would march out together like an army in.

Eric Frank
Formation, like three ants next to each other in a two meter long column. It's very peculiar, and it looks like a long snake walking on the ground.

Nell Greenfield Boyce
So when the ants get to the termites, they would fight. There's like this huge battle, and when it was over, he would see the ants start picking up dead turmoil to carry home for food. But then he noticed that some of the ants that were marching home weren't carrying termites, they were carrying other ants, wounded ants.

Emily Kwong
So they were carrying their fallen comrades home.

Nell Greenfield Boyce
Yeah, basically. Just like soldiers, you know?

NPR Sponsor
Yeah.

Emily Kwong
Instead of no man left behind, no ant left behind.

Nell Greenfield Boyce
Exactly. And so he was really surprised by this. And he did a study where he marked the injured ants to see what happened to them. And it turns out in nearly every case, the injured ants that were carried home made a full recovery.

Eric Frank
We saw them again participating in hunts the next day.

Emily Kwong
What a rebound.

Nell Greenfield Boyce
Yeah. So he got interested in how they recovered, and by studying this, he learned that ants will lick and groom a buddy's wound in the hours after the injury. And without this treatment, the injured ants would usually die. So it turns out this particular species of ant has a special gland that's full of antimicrobial secretions.

Worker ants basically apply these secretions to the open wounds of their nest mates. It's basically like giving their injuries antibiotics.

Emily Kwong
But are these the ants that engage in medical amputation?

Nell Greenfield Boyce
No. Okay, so that's something Eric Frank only observed more recently. And when I talked to him, he told me it was because of the pandemic, because he couldn't travel. So he started studying this other ant. The common name is the Florida carpenter antennae.

Emily Kwong
I feel like so many scientists had to make do during the pandemic. You know, people learned cool stuff just by studying what was around, which in his case was the Florida carpenter ant.

Nell Greenfield Boyce
It's true. I wish somebody would put, like, a compilation of, like, pandemic desperation science, where, like, scientists looked around and saw what was there. Anyway, so he's now looking at this other ant, and he knew that this species did not have that special gland that he'd been studying before.

Eric Frank
So I just very naively wondered, well, how would they act if they get confronted with injuries?

Nell Greenfield Boyce
So these are, you know, injuries that they did experimentally in a controlled way in the lab. Right. And pretty much right away, he and his colleagues saw ants amputating their buddies injured legs.

Emily Kwong
This has been my big question this whole time. When you say amputating, how does that work? Ants don't have tiny little bone saws and surgical tools.

Nell Greenfield Boyce
No, they don't. Okay, so here's what happens. An injured ant, you know, an ant with an injury in, like, the upper part of its legend of, will present that leg to a nest mate. And this nest mate will lick at the wound with their little mouth parts. You know, like, sort of move up to the shoulder area and, like, up at the joint, like, start chewing through the leg to sever it. And this takes a while, like, many.

Eric Frank
Minutes, and you can see the other ones not moving, not really flinching and accepting it. And once the leg is removed and it falls off, the other one will come back and lick the little stump that's left, and it will still be presenting it. So it's clearly collaborating and wants the same thing as the one that is treating it.

Nell Greenfield Boyce
So either the injured ants are just stoic or they don't feel pain or what, but they're clearly working together to make this thing happen.

Emily Kwong
The depth of ants, I just didn't realize any of this. And you said earlier that this procedure, for lack of a better term, is life saving. How do researchers know that?

Nell Greenfield Boyce
So they found that ants with similar injuries that were kept away from their nest mates, they didn't get amputations. Those ants frequently died. So, you know, no amputation, high chance of dying. And their studies show that's because without amputation, an infection from an open leg wound can travel to the rest of the ant's body and kill it. And Eric Frank told me to see if it was really amputation. That was the key thing. He figured he'd just try his hand at performing ant surgery.

Eric Frank
Since I observed these amputations, I was like, well, I'm pretty sure I can artificially conduct the same kind of amputations.

Nell Greenfield Boyce
And so even when it was done by a human, the amputation treatment was just as effective in helping injured ants.

Eric Frank
Recover, really confirming that these amputations were saving the lives of the infected individuals.

Nell Greenfield Boyce
Pretty cool, right?

Emily Kwong
So cool. But wasn't there supposed to be some clinical judgment involved here? You alluded to earlier that ants aren't just whipping off legs right and left. They are making decisions about what to amputate.

Nell Greenfield Boyce
Well, decisions. I mean, that's a debatable word, but, yeah. There is a part of this that the researchers found perplexing. For a while, they had been studying ants with injuries to the upper leg and witnessing amputations at the shoulder. And so after they'd done this, for a while, they were like, okay, what if an ant had an injury farther down, like, towards its little, like, ant foot?

Emily Kwong
Okay.

Nell Greenfield Boyce
So it turns out that for injuries lower down, like, what would be the human shin, the ants did not amputate legs at all. So amputation was only occurring when the injury was high up in, like, what would be a human thigh. I was like, that doesn't make sense. And it took Erik Frank and his colleagues, like, a year of lab work to figure out what was going on. And basically, the important thing is that the body of an ant is just not like the human body.

Emily Kwong
How so?

Nell Greenfield Boyce
Well, they don't have hearts like we do, for one thing.

NPR Sponsor
Oh.

Nell Greenfield Boyce
There are these muscular pumps distributed throughout the ant's body, including in its legs, especially in the thigh, the upper leg area.

So it's weird, but, like, what it means is that if an ant gets injured in that upper leg area, the muscles are damaged, and so the pumping of liquid doesn't happen as quickly. And that means infection actually spreads slowly, more slowly than it would if the injury was lower down on the leg. And so basically what it means is that amputation really only has a shot at blocking the infection for upper leg injuries, even though it doesn't seem like it should be that way. But that's how it is for ants.

Emily Kwong
Right. And then if the infection is lowered down on the leg, the infection kind of spreads fast. The amputation can't work, and it's deemed a little bit of a lost cause.

Nell Greenfield Boyce
Yeah. So the researchers tested all of this experimentally in the lab, and they showed experimentally that amputation is not effective for lower leg injuries. And so that's why the ants don't do it.

Emily Kwong
They are like doctors, they're like surgeons.

Nell Greenfield Boyce
So for those injuries, they just spend a lot of time tending to the wounds, licking them, and whatever they do is often life saving.

Emily Kwong
It's amazing to me that this treatment is so targeted to a specific kind of injury, they are making what we would call a clinical evaluation.

Nell Greenfield Boyce
Yeah, but, you know, they're not exactly like doctors. Like, you know, it's not like they're sitting there thinking about it and weighing the pros and cons. I talked about this with some other ant experts who weren't involved in this study, like Daniel Kronauer, he's at Rockefeller University. And he told me, you know, remember, this is evolution working. Not like individual ants with, like, medical degrees and medical knowledge.

Daniel Kronauer
They've basically evolved over, like, thousands and thousands and probably millions of years to be kind of programmed in quotation marks to react to different kind of injuries in a certain way.

Nell Greenfield Boyce
It's all to help the colony as a whole survive. And he told me, besides these antimicrobial secretions and amputations, ants sometimes do other things that seem a lot like human public health measures. So, for example, there's studies showing that if ants in a nest have certain contagious infections, the social networks of the nest will sort of get reconfigured. There's less connections, like, everything becomes much more modular.

Emily Kwong
So they'll quarantine, essentially, yeah.

Daniel Kronauer
You basically socially isolate individuals that carry an infection. That, of course, reminds you of the COVID pandemic, maybe, and what we were supposed to be doing.

Nell Greenfield Boyce
And then there's other studies showing that ants with an infectious disease might just wander off from the colony and, like, go die somewhere else.

Emily Kwong
Oh, that's very self sacrificing of that antennae and, you know, again, the amputation and antibiotic parts, it all sounds very caring.

Nell Greenfield Boyce
Yeah, but, like, it's not like it's love, it's not like empathy or anything. It's just that, like, saving ant lives means that the colony has bigger armies and more success, just generally speaking. Right. That's, like, one more soldier for your cause, right?

Emily Kwong
Okay, I'm hearing you. This is evolution at work. These are adaptive strategies for the good of the colony. Self isolation, amputation, wound licking.

It's all very cool. And I guess what's striking to me is, given how useful it is, how have we not noticed this before? I mean, we've been living alongside carpenter ants for a long time.

Nell Greenfield Boyce
Yeah, I am sure people listening to this have seen these ants before, right? Yeah. I mean, they're not like the little black ants that invade your picnics, but the florida carpenter ant is, you know, this brownish ant like a centimeter across. It's, like, in lots of places where people live. You know, that is the part that really struck this other guy. I talked to an ant expert called Clint Pennock. He's at Auburn University.

Clint Pennock
This is an ant that I grew up with in my backyard.

And so it's really interesting to see such a sophisticated behavior, you know, that's literally happening in people's backyards from a common carpenter ant.

Nell Greenfield Boyce
It makes me wonder, like, what else the ants are doing.

Emily Kwong
Insects in general feel like the final frontier to me. There's so much we don't know about what they do. And I hope when you find something else, you come on the show and talk about it, and I'll.

Nell Greenfield Boyce
Absolutely. I mean, I do admire your seemingly endless desire to hear this stuff. And, you know, if I know ants, like, pretty soon we're gonna be hearing about something else. There's gonna be another supposedly unique to human activity that it turns out, oh, yeah, ants have been doing for millions of years.

Emily Kwong
Yeah. I mean, what would be really weird is if they had their own science podcast.

Nell Greenfield Boyce
I mean, it would be serious competition for you, I gotta say. Cause I would listen to that all day long. All day long. Emily, I would love to co host with Annette.

Emily Kwong
This episode was produced by Hannah Chin. It was edited by our showrunner, Rebecca Ramirez, and fact checked by Nell Greenfield Boyce. Beth Donovan is our senior director, and Colin Campbell is our senior vice president of podcasting strategy. I am Emily Kwong. Thank you for listening to Shortwave, the science podcast from nPrdez.

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