Why a chimp 'civil war' shows how societies collapse

In the mid-1970s, primatologist Jane Goodall witnessed something that changed her opinion of chimpanzees forever: A four-year conflict amongst the chimpanzees she was studying in Tanzania. Chimpanzees that knew each other started killing each other. It was essentially the primate equivalent of a civil war. And now, it’s happening again: Fighting within the largest known community of chimpanzees. NPR science correspondent Nate Rott https://www.npr.org/people/348779465/nathan-rott helps us break down what’s going on and what it could tell us about how human communities can fall apart. Read all of Nate’s story here https://www.npr.org/2026/04/13/nx-s1-5781149/chimpanzee-civil-war-primate-conflict-anthropology. Interested in more science? Email us your question at [email protected] mailto:[email protected]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. See pcm.adswizz.com https://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 https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:18Emily Kwong?

  You're listening to Short Wave from NPR.

• 0:24Emily Kwong?

  Hey, Short Wavers. Emily Kwong here. And today's story starts with the late and legendary primatologist Jane Goodall. During her field work with chimpanzees in the mid 1970s, she witnessed something that changed her opinion of chimps forever.

• 0:37Speaker 02

  I used to think, well, they're very like people, but nicer. And then I realized that when opportunity arises, they have this nasty, brutal side to them, just like we do.

• 0:47Emily Kwong?

  This is an interview Jane did with Terry Gross on Fresh Air back in 1993. And what Jane Goodall is referring to here is a four-year conflict that broke out amongst the chimpanzees she was studying in Tanzania. Chimps that knew each other started killing each other. It was essentially the primate equivalent of a civil war.

• 1:07Speaker 03

  You know, when humans fight a war, you always want to know, what is the war about? What is the motivation? Who is wronging who? When chimps fight a war, what is it about?

• 1:17Speaker 02

  Well, this particular war was the only one we've ever seen, and we're not too sure. I think we shan't be very sure until it happens again.

• 1:25Emily Kwong?

  Well, now it's happening again. In the largest known community of chimpanzees in the world, and scientists are documenting it in real time with videos like this.

• 1:39Speaker 04

  Yeah, one of the things that's kind of wild about this whole story, Emily, is that like, very much like the human wars that are going on in the world right now, there is now cellphone footage of these conflicts happening.

• 1:48Emily Kwong?

  Ah, NPR's science correspondent Nate Roth, hey there.

• 1:50Speaker 04

  Hey, Emily.

• 1:51Emily Kwong?

  So you've been talking to some of these researchers watching this unfold?

• 1:54Speaker 04

  I have, yeah, including the primatologist who took that video. His name is Aaron Sandel, and he originally went to study this group of chimpanzees to try and better understand friendship in primates.

• 2:05Speaker 05

  Now, my focus has gone from understanding friendship to sort of how do friendships... Fall apart. How do communities fall apart?

• 2:12Emily Kwong?

  Oh, he sounds so sad.

• 2:14Speaker 04

  I know.

• 2:15Emily Kwong?

  But it's also kind of fascinating to me. Just as a scientist, sometimes you got to go where the research leads.

• 2:19Speaker 04

  Totally. I mean, Aaron says he'll probably spend the rest of his career trying to understand this ongoing event because it is super rare. Like scientists know that some other animals engage in coordinated attacks against each other, like what we might call war, right? That includes ants and lions and wolves. But these kinds of permanent fusions that result in violence, like a group of animals breaking apart forever and fighting each other, is super rare. With chimpanzees, they think this only happens like once every 500 years.

• 2:50Emily Kwong?

  And the researchers have been watching this whole thing happen?

• 2:53Speaker 04

  Yeah, from the very start, before it began, and even as it's ongoing right now.

• 2:59Emily Kwong?

  Today on the show, a civil war amongst one of humanity's closest living relatives.

• 3:04Speaker 04

  And what it can teach us about how communities fall apart.

• 3:07Emily Kwong?

  I'm Emily Kwong.

• 3:08Speaker 04

  And I'm Nate Rot, and you're listening to Short Wave, the science podcast from NPR.

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• 4:21Emily Kwong?

  All right, Nate, where is this civil war happening?

• 4:24Speaker 04

  Yeah, it's happening on the western border of Uganda in this densely forested national park. There are multiple communities of wild chimpanzees that are studied there, but the ones we're going to be focused on are part of what's called the Ngogo group. Researchers have been observing this group for more than 30 years.

• 4:40Emily Kwong?

  That is a long time to be studying the same group of chimps.

• 4:43Speaker 04

  It is, and that's part of what makes this so interesting because the primatologists who were working there had decades of observations of these chimpanzees. So they knew who was hanging out with who, who mated with who, they knew the chimps' social bonds. Aaron Sandel, the primatologist we heard from earlier, started working there in 2012. He's now at the University of Texas at Austin.

• 5:03Speaker 05

  They were so used to people by then that most of them just ignored me.

• 5:09Emily Kwong?

  A tightly knit group. How many chimpanzees are in this Ngogo group?

• 5:14Speaker 04

  Yeah, so when researchers started tracking them in the mid 90s, there were about 100, which is a lot. Aaron says that like the average group of a chimpanzees is about 50. But by the time Aaron started working there, there were nearly 200 individuals in this group. Yeah, so a lot. Now, he does say there were like substructures in the community, almost like neighborhoods of chimps that spent more time together.

• 5:35Speaker 05

  But still, there was no sign that the group would split until 2014. We started seeing the first signs of these neighborhoods being really distinct. And then it was really in 2015 when the social network changed in a dramatic way.

• 5:50Speaker 04

  Aaron says he can remember the specific day, June 24, 2015. He was with a group of chimps from the western cluster, the western neighborhood, when they heard other chimpanzees nearby, presumably from the central neighborhood. So these were all chimps that knew each other, but the western chimps did not act like it at all.

• 6:09Speaker 05

  They got quiet all of a sudden. They started touching each other in this reassurance, like they were really nervous. And to me, this seemed like they were acting as if they were hearing outsider chimps. And then when the chimps from the central neighborhood got closer, rather than reuniting in this typical chimpanzee fashion where they're constantly mixing and... Mingling and instead of doing that, the Western chimpanzees ran and the Central chimpanzees chased them. And nothing really like that had ever been observed before. And then they avoided each other for six weeks.

• 6:40Emily Kwong?

  It's like a bad, bad rift. Um, so do they know why this happened?

• 6:46Speaker 04

  No, they don't. And it wasn't like this was it, right? Like the groups had split. Aaron says after those six weeks, they did start interacting again, but over the next few years, it became increasingly clear that the groups were getting more polarized. They spent less time together. The friendships that existed, if we want to call them that, started fading away.

• 7:05Speaker 05

  And by 2018, they were completely separate groups, no longer peacefully interacting. And that was when we saw the beginning of these lethal attacks.

• 7:17Speaker 04

  Yeah, this is from a voice memo that Aaron took of an attack in 2021.

• 7:20Speaker 07

  Alfred said Westerners attacked Bartley and Miles. Miles and Jackson ran.

• 7:30Emily Kwong?

  That's kind of horrifying.

• 7:31Speaker 04

  Yeah, it is. It like the first time he sent that to me, I was like, whoa. Uh, when I was talking to Aaron, you know, I asked him, well, let's just listen to it. As a scientist, as a primatologist, it's got to be remarkable, right? To observe this happening in real time.

• 7:49Speaker 04

  But is it also kind of sad?

• 7:51Speaker 05

  Definitely. I saw the first two lethal attacks. And like the first lethal attack was a chimp that I'd really watched grow up. I even remember the night before he was killed, I saw him and he was sort of running around and grooming with this adolescent female. And I remember even coming back at the end of the day that night to the campsite and sharing with the other researchers. Oh, Errol, this chimp, he's really acting like an adult. And then the next morning I saw them kill him.

• 8:21Emily Kwong?

  That's so sad.

• 8:22Speaker 04

  Yeah, I mean, Aaron says he feels in some respects kind of like a war correspondent. You know, he's just trying to observe and document everything that's happening as this has spread from males attacking males to even males attacking infants.

• 8:35Speaker 05

  You know, I'm trying to understand this really rare behavior. And I'm thinking about what's causing this, like, what is it? Why is this happening? What is the perspective from the chimpanzees themselves? Because we're seeing this sort of shift of relationships that you don't get when you just watch animals generally.

• 8:56Emily Kwong?

  Yeah, let's talk about the science of what's going on. I mean, the only other example of these kinds of wars, lethal attacks, it sounds like is what Jane Goodall saw during her work in Tanzania, right?

• 9:07Speaker 04

  Yeah, that is right. And but that case is a bit complicated because back then, the researchers were giving the chimpanzees bananas to sort of speed up the habituation between humans and chimps. So some researchers have hypothesized that that might have played a role in what happened in Tanzania.

• 9:23Emily Kwong?

  The banana wars.

• 9:24Speaker 04

  The banana wars, yeah. I talked to Anne Puzey, retired primatologist who worked with Jane Goodall in Tanzania during that conflict in Gombe National Park, and asked her what she thought of this new study.

• 9:34Speaker 07

  Here we have a case where they'd never fed them, but they've never interfered in any way in this community of chimps. And yet they've seen this fishing and and this killing of one set of males by the other.

• 9:49Emily Kwong?

  When she looks at the the observations happening in Uganda right now, what does she make of it?

• 9:55Speaker 04

  She says she was struck by how many similarities there were. You know, for example, in Gombe, where she worked, there was some natural deaths of adult males before the conflict started. And the same thing happened in the Ngogo group.

• 10:07Emily Kwong?

  Oh.

• 10:08Speaker 04

  So maybe that frayed the social fabric enough to allow these two groups to like start seeing each other as enemies.

• 10:13Emily Kwong?

  Like the elders were gone and it created new social relationships?

• 10:18Speaker 04

  Yeah, like maybe some of the chimpanzees that had a close relationship with others passed away. And so all of a sudden, those kind of like connecting threads in the community were gone. But it also could have been about territory. Or resources, you know, in both cases, the researchers still aren't really sure what caused this. But what they do know is that the Gombe conflict didn't end until one group essentially killed off the other. That has not happened with the Ngogo group. The fighting is still ongoing, and the researchers are just trying their best to follow along and see what happens.

• 10:51Emily Kwong?

  And I suppose the researchers can't intervene. That's the nature of this work. You know, because chimpanzees are one of our closest living relatives, does this help us understand how war between humans happens? Am I anthropomorphizing too much?

• 11:07Speaker 04

  No, I mean, I think that's like, I think that's a really natural question, and it's something that everybody I talked to brought up. I asked Anne for her thoughts on it, and to be fair, she kind of hedged. I mean, it's rather uncomfortably familiar, seeing how these relationships can break down and then lead to antagonisms between groups which weren't there before. Uncomfortably familiar feels like an appropriate way, right?

• 11:34Emily Kwong?

  Yeah.

• 11:35Speaker 04

  You know, but Anne strongly suggested I talk to a primatologist named Michael Wilson at the University of Minnesota, who studied conflict in primates, including us. And so I reached out to him.

• 11:45Speaker 07

  There are several different ways of viewing it. And one is thinking, well, they're our closest living relatives. So if if they do something and we do something, then maybe our last common ancestor did it, and we're doing it because of our shared evolutionary history.

• 12:01Speaker 04

  But here's the problem. Our other closest living relative kind of throws a wrench in that whole theory, because bonobos are just as similarly related to humans as chimpanzees are, and they do not kill each other like this.

• 12:13Emily Kwong?

  But I thought bonobos were kind of mean. You're saying they don't lethally attack each other, though?

• 12:17Speaker 04

  Oh, so they'll show aggression towards each other. There was a study that was done a couple of years ago that showed that says that male bonobos are actually more likely to push or bite or hit each other than chimpanzee males. But researchers have never seen one bonobo kill another.

• 12:32Emily Kwong?

  Wow.

• 12:32Speaker 04

  So in that sense, Michael says, it's kind of hard to argue that we have that shared genetic predisposition for violently turning on each other. But he still thinks that there's a lot that we can learn from observations like this.

• 12:46Speaker 07

  I think it's clear from this study and from other studies of chimps and other animals that you can get these kinds of conflict without a lot of the things that we think about being the sources of conflict in humans. You know, lions don't have religion and political parties or ideology, and neither do wolves and/or ants, for that matter.

• 13:09Emily Kwong?

  Neither do chimpanzees. And yet, as you said earlier, all of these animals engage in this type of intra-group fighting.

• 13:16Speaker 04

  Yeah, and this is one of the points that Aaron and his co-authors really hit on in their new study of this most recent chimpanzee war that was published in the journal Science, that even without all of those things, without religion, without ethnicity, without politics, this kind of conflict can emerge. So maybe its cause is as simple as the breakdown of smaller relationships between individuals in a community.

• 13:38Emily Kwong?

  Yeah, the rupture of social bonds, which, you know, we see all over the world. I don't know if that makes me feel better or worse about it, but it's the reality.

• 13:47Speaker 04

  Yeah, that's fair. For what it's worth, Emily, Aaron says it actually makes him feel a little more optimistic. Because if that is the case...

• 13:56Speaker 05

  That means that interventions for peace actually rest within our own lives, in our own relationships in everyday life. Like with the chimps, it's like you act like a stranger, you become a stranger. I want to avoid that in my own life.

• 14:11Speaker 04

  Simple lesson from chimpanzees.

• 14:14Emily Kwong?

  Nate Roth, thank you for this reporting.

• 14:15Speaker 04

  Yeah, Emily, thank you. And I should say, do not be a stranger, right? Let's take something from this.

• 14:20Emily Kwong?

  I never could. If you liked this episode, please share it with a friend, because it helps our show grow. And while you're at it, download the NPR app. It's totally free and a personalized way to bring you the very best of the public radio cosmoverse. Your favorite podcasts like us and your local station and the world's biggest stories all in one place. Download the NPR app in your app store today. This episode was produced by Rachel Carlson and edited by Rebecca Ramirez. It was fact-checked by Tyler Jones. The audio engineer was Jimmy Keely. I'm Emily Kwong. Thanks for listening to Short Wave from NPR.

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