You're listening to Shortwave from NPR.
Hey, Shortwavers, Emily Kwong here.
Today's story starts with the late and legendary primatologist Jane Goodall.
During her fieldwork with chimpanzees in the mid-1970s, she witnessed something that changed her opinion of chimps forever.
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.
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 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.
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?
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.
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.
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 cell phone footage of these conflicts happening.
Oh, NPR science correspondent Nate Rott.
Hey there.
Hey, Emily.
So you've been talking to some of these researchers watching this unfold.
I have, yeah, including the primatologist who took that video.
His name is Aaron Sandell and he originally went to study this group of chimpanzees to try and better understand friendship in primates.
Now my focus has gone from understanding friendship to sort of how do friendships work, fall apart, how do communities fall apart?
Oh, he sounds so sad, i know, But it's also kind of fascinating to me.
Just as a scientist, sometimes you got to go where the research leads.
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 fissions 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.
And the researchers have been watching this whole thing happen?
Yeah, from the very start, before it began, and even as it's ongoing right now.
Today on the show, a civil war amongst one of humanity's closest living relatives.
And what it can teach us about how communities fall apart.
I'm Emily Kwong.
And I'm Nate Rott.
And you're listening to Shortwave, the science podcast from NPR.
All right, Nate, where is this civil war happening?
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.
That is a long time to be studying the same group of chimps.
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 Sandell, the primatologist we heard from earlier, started working there in 2012.
He's now at the University of Texas at Austin.
They were so used to people by then that most of them just ignored me.
A tightly knit group.
How many chimpanzees are in this Ngogo group?
Yeah.
So when researchers started tracking them in the mid 90s, there were about 100, which is a lot.
Aaron says it like the average group of 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.
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.
Aaron says he can remember the specific day, June 24th, 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.
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.
It's like a bad, bad rift.
So do they know why this happened?
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.
And by 2018, they were completely separate groups, no longer peacefully interacting.
And that was when we saw. the beginning of these lethal attacks.
Yeah, this is from a voice memo that Aaron took of an attack in 2021.
That's kind of horrifying.
Yeah, it is.
Like the first time he sent that to me, I was like, whoa.
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.
But is it also kind of sad?
Definitely.
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, Aaron was chimp.
He's really acting like an adult.
And then the next morning I saw them kill him.
Oh my gosh, that's so sad.
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.
You know, I'm trying to understand this really rare behavior and I'm thinking about what's causing this.
Like, 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.
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,
Yeah, that is right.
And but that case is a bit complicated because back then the researchers were given 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.
The banana wars.
The banana wars.
I talked to Ann Pusey, a retired primatologist who worked with Jane Goodall in Tanzania during that conflict in Gambe National Park and asked her what she thought of this new study.
Here we have a case where they never fed them.
They never interfered in any way in this community of chimps.
And yet they've seen this fishing and this killing.
When she looks at the observations happening in Uganda right now, what does she make of it?
She said 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.
So maybe that frayed the social fabric enough to allow these two groups to start seeing each other as enemies.
Like the elders were gone and it created new social...
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.
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?
No, I mean, I think that's like I think that's a really natural question.
And it's something that everybody I talk to brought up.
I asked Anne for her thoughts on it.
And to be fair, she kind of hedged.
I mean it 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?
Yeah.
You know, but and strongly suggested.
I talk to a primatologist named Michael Wilson at the University of Minnesota, who studied conflict and primates, including us.
And so I reached out to him.
There are several different ways of viewing it.
And one is thinking, well, there are 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.
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.
But I thought bonobos were kind of mean.
You're saying they don't lethally attack each other, though?
Oh, so they'll show aggression towards each other.
There was a study that was done a couple of years ago 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.
Wow.
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.
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.
Lions don't have religion and political parties or ideology, and neither do wolves and or ants, for that matter.
Neither do chimpanzees.
And yet, as you said earlier, all of these animals engage in this type of intragroup fighting.
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
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.
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,
That means that interventions for peace actually rest within our own lives and 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.
Simple lesson from chimpanzees.
Nate Rott, thank you for this reporting.
Yeah, Emily, thank you.
And I should say, do not be a stranger, right?
Let's take something from this.
I never go.
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This episode was produced by Rachel Carlson and edited by Rebecca Ramirez.
It was fact checked by Tyler Jones.
The audio engineer was Jimmy Keeley.
I'm Emily Kwong.
Thanks for listening to Shortwave from NPR.
