Science Friday - Maybe Bonobos Aren't Gentler Than Chimps | Art Meets Ecology In A Mile-Long Poem

Episode Date: May 2, 2024

A study found aggression between male bonobos to be more frequent than aggression between male chimpanzees. Also, visual artist Todd Gilens created a walkable poem along Reno’s Truckee River that draws parallels between urbanism and stream ecology.Bonobos Are Gentler Than Chimps? Maybe Not.Bonobos are a species of great ape, along with gorillas, orangutans, and chimpanzees. Over the years, they’ve gained a reputation as being calmer and more peaceful than other ape species. But recent work published in the journal Current Biology finds male bonobos may be just as aggressive as male chimpanzees, if not more so.Dr. Maud Mouginot, a postdoctoral associate in anthropology at Boston University, led the study, in which observers followed individual chimps and bonobos in the wild from morning to night, keeping track of all their interactions. The researchers found that bonobos engaged in 2.8 times more aggressive interactions and 3 times as many physical aggressions as the chimpanzees in the study.Dr. Mouginot joins guest host Arielle Duhaime-Ross to discuss the findings, what might account for the differences in aggressiveness, and what it can teach researchers about primate behavior.Art Meets Ecology In A Mile-Long PoemOne year ago this month, we launched our podcast Universe Of Art, which features arts-focused science stories, like the science behind “Dune” and why a group of science illustrators created an online celebration of invertebrate butts. And to our surprise, a lot of you wrote in to tell us about your own science-inspired art projects, including artist Todd Gilens.Gilens is a visual artist and designer who collaborated with the city of Reno, Nevada, to create a mile-long poem, called “Confluence,” printed on the city’s sidewalks bordering the Truckee River. He was interested in how water shapes landscapes, and how urban architecture can mirror those natural processes. He later found the Sierra Nevada Aquatic Research Laboratory, a University of California field station near Mammoth Lakes, and spent several field seasons with them to learn about stream ecology.Universe Of Art host D. Peterschmidt sat down with Todd to talk about how the poem came together and why he spent four field seasons in the Sierra Nevada with stream ecologists to create the piece.Transcripts for each segment will be available the week after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Bonobos have a reputation as being the calmest, most peaceful of the great apes. I saw like two bowl of fur running in the trees one after the other, and the other one was screaming, crying, and I was like, what is going on? And the field assistants were not surprised. I was like, oh, they're just fighting. That's an aggression. New research involving thousands of hours of observation shows that chill reputation may not always hold true. It's Thursday, May 2nd, and you're listening to Science Friday.

Bonobos are a species of great ape, along with gorillas, orangutans, and chimpanzees. Recent work published in the journal Current Biology finds male bonobos may be just as aggressive as male chimpanzees, if not more so. Guest host Ariel Duemross talks with Dr. Maud Mugino, postdoctoral associate in the Department of Anthropology at Boston University, about that work. Welcome to Science Friday. Thank you. Thank you for the invitation. Thank you so much for coming on the show. So for listeners who might not have all their great apes straight, who are the bonobos and where are they found? Bonobos are one of our closest living relative with chimpanzees.

They can be found in the Democratic Republic of Congo. So we say that they're an endemic species, which means it can only be found there. And there is around 15,000 left. When we look at a tree, we have humans and right next to them we have a branch, which is what we call the Pan Branch, which group Bonobos and chimpanzees. So they are as close to us as chimpanzees are. How did they get this reputation for being so peaceful? And how did that reputation persist for so long if it's not quite right? That is a great question. I think it started because the first time researchers saw bonobos. There's a lot of behavior that were not observed in chimpanzees,

such as intergroup interactions. So in Bonobos, a group of Bonobos can encounter. It can spend time together, share food, sometimes sleep together in trees, groomed together. And in chimpanzees, a group of chimpanzees cannot encounter. They will always avoid each other or probably aggress each other. And also, in Bonobo's male do not coerce female, which means they do not push female into mating with them.

And we don't observe infanticide. are killings in bonobos compared to chimpanzees. And I think all those behavior gave that perception that Bonobo are peaceful. I see. Okay. So what made you want to look at this question in the first place? There is a different thing that makes me want to look at it. First of all, there is a study that came out in 2017 that looked at reproducese, which is inequality in reproductive success among males. So that means you can have high reproductive skew. where some males are going to sire more offspring than others. And usually, if we have high reproductive skew in a species,

that means there is high context competition between males. So males are going to fight between each other. And this study compared bonobos and chimpanzees, and they found that there was high reproductive skew in bonobos compared to chimpanzees. So the question was, how do bonobo obtain such high reproductive skew if they're not so aggressive? So we wanted to look at actually rate of aggression among those two species. And that sounds pretty basic, like wise hasn't been done before. And there is actually only one study that looked compared directly bonobos and chimpanzees,

but they did not use the same sampling method on the field. So for us, we're like, okay, let's do this by using the exact same method on the field from the start. So we know what we compare. I was really struck by the literal years of observational data that your team had to gather to reach these conclusions. Can you tell me about that? How did you get these data points? Yeah, that's a great question. So if we start with chimpanzees, we are at Combinational Park. So it's the Jen Goodall site. So there is like, I don't know, 60 years of data. For Bonobos, we started to get good data from 2019,

which is a lot less than what we have for chimpanzees. It's actually hard to get good male focal follow. So focal follow is when you follow one individual for a girl today. And when you do that above study, you want as much as possible so you can have a lot of variation. And for this, that might ask to actually get two years or even more of data. So that's why we have those numbers. So let me get this straight. You would get up and literally follow around one bonobo all day just watching what this male did.

Exactly. Yes. How long were your days? And what was that like? So for me, all the data we have actually come from field assistants mostly, not from my own data, because I haven't spent two years, unfortunately, on the site. But yeah, usually we spend, I might spend like, I don't know, 12 hours. So we wake up at 3.30 in the morning, go. start your day at four, try to join the bonobo around five because that's the time they wake up, and then you follow them all day until they go back to bed, so in their nest in trees. And this, they're probably going to end up there, they're around 5 p.m. So that's a pretty long day at the end.

Wow. All right. So what exactly did your team observe over, you know, the observational period? So they observed a lot of different behavior. Personally, the first. thing, when I arrived on the field, my first week, I would always remember, it was like still pitch dark, so I couldn't recognize really the individual. And I saw like two bowl of fur running in the trees one after the other. And the other one was screaming, crying. And I was like, what is going on? And the field assistants were not surprised. I was like, oh, they're just fighting. That's an aggression. When we say that male bonobos are just as aggressive as male chimps or even more so, what exactly does that mean? You know, can you

quantify that? Yeah, so we have some quantity. We observe that male bunderbors act 2.8 times more than aggressively than male chimpanzees. However, we have to keep in mind that when we compare things like this, it's a little bit too straightforward. That's why we have statistical analysis that allow us to control for between individual variation, group variation, a number of males also in the group, but even with the statistical analysis, we observed a difference between the two species. Okay, I see. So chimps are notorious for their aggression, right? Both males and females tend to fight with other members of their community, and they do so pretty regularly. They can also recover from those fights fairly quickly in terms of their relationships with the chimps that they have fought

with. They're known for making up. They reconcile and even console each other. Are bonobos the same? Are they different? What did you observe? Actually, for reconciliation, that's studies that are like I start going on right now. There is one study that look at it and they found a lot less reconciliation among bonobos than chimpanzees. Really? Yeah, at least among males. That's interesting. Yeah, it is.

And it kind of also makes sense if we look at how dynamics works in the society of bonobos and chimpanzees. In Bonobos, male are very individualistic or more individualistic in their strategy. They do not form coalitions of males. So they tend to fight. And if they act aggressively against each other, they know the cost and the benefits of each aggression. Inchipans is the dynamic is very different because male-mec coalitions within group fight, but also for between-group fight. So the cost and benefits of aggression is different. And then the process of reconciliation are not going to have the same benefits.

Okay, right, because there are structural differences between these different species, right, in terms of how their communities are built. Can you tell me about that? Yes, in chimpanzees, male-form coalitions. Female rarely or not do so. And male are dominant over females. So, male-form coalition for within group fight and to do border patrols and some time-to-time, some killing reds if they see one or two individuals by themselves. And Bonobos is totally different.

Male rarely or do not form coalitions. But female form coalitions. And they do so sometimes against males. And both male and females in Bonobos are co-dominant. So it's a total different dynamic. Which might explain some of the differences, but it's interesting that you found similarities. So you were looking at individual actions of a few apes from specific ape communities of Bonobos and chimps. Can you extrapolate that out to an entire species?

It's actually one of the thing of the study is that we compare only one side of bonobo with one side of chimpanzees. So the main idea is that I would be really nice to have more sites to understand better the variation. What I can tell from this study is that we think that they use aggression differently because of those different coalitionary patterns. So because male chimpanzees form those coalitions, when they act aggressively against another male, they might face a coalitionary retaliation, which is very expensive. It's very risky. On the other way, if there are a lot of male chimpanzees acting against one male chimpanzees, then the costs are lower. But in any case, when they act aggressively against a member of their own community, it's costly because this member might, have been a future partner for between group interactions, so defending the group.

So aggraition in general is less predictable and more expensive for chimpanzees compared to bonobos. So that might be why we observed us difference of rate of aggression between the two species. Is it painful for you to be able to conduct a study on them? So yes, there are only 15,000 left of them. or this is what the IUCN has evaluated. And we don't really know exactly the number because they're so remote in the rainforest that it's hard to get an actual predictable number.

And I think research on bonobos really allow us to better understand them and then to better protect them. For example, at the Coquale Bonobo Reserve, it's a reserve, so allowing us to really protect this species or a group of bonobos, which is really great to protect them from pouches,

for environmental destruction. So I think research are really important, and I'm happy to be part of such research to help also protect the species. So what's next? Where do you go from here with this research? So from here, my dream research would be to actually get more studied,

more field to do the same analysis with their chimpanzee group or bonobo group, so we can get a better understanding of the variation between species but also within species in terms of aggression. Also, for me, I was really interested in the dynamic between male and female. If we look at the data, they're very opposite in chimpanzees, male act aggressively against females, but females tend to avoid to act aggressively against males. And Bonobos is to toll different dynamics where female act aggressively against males,

but male tend to avoid acting aggressively against the female. And I'm really interested in that dynamic. All right. Well, I hope you get to do that kind of research in the future. We'll be keeping an eye on that. Thank you. Dr. Mood Mugino is a postdoctoral associate in the Department of Anthropology at Boston University. Thank you so much for talking with me today.

Thank you for your time. One year ago, we launched our podcast, Universe of Art, which features stories at the intersection of art and science. And to our surprise, a lot of you wrote in to tell us about your own science-inspired art projects that you're making in your spare time. For this week and the next, we're going to feature some of these listeners for Universe of Arts one-year birthday. Dee Peter Schmidt, who hosts the show, talk to one of these artists who embedded with scientists in the field for many seasons to make his work come to life. My name's Todd Gillens, and I'm a visual artist, and I do mainly temporary public projects. People encounter the work, not actually knowing why it's there or that it's artwork. They just see something that's a little different than what they're.

expected. But when Todd started working on this one project, which took nine years to produce, he knew the only way he could finish it was by diving into the science. I really wanted to understand not just at a superficial level what water does in the landscape. Todd worked with the city of Reno, Nevada, to create a mile-long poem printed on its sidewalks that border the Truckee River, which is fed by the melting snowpack from the nearby Sierras. He'd been thinking about sidewalks and how they're like streams in the mountains. Both of them are narrow channels that direct the flow of water or people with life flourishing along the way. And for him, poetry was a way to immerse a passerby in a stream of words, letting the flow of the poem carry them through the city's connections to the nearby mountains,

like a leaf caught in the flow of a river. But he didn't exactly know how these stream channels change a landscape. I wanted to understand this process and what was actually going on there so that when someone's reading a piece of the poem, they can imagine what had been there in that very spot before urbanization and also what is still going on in the mountains just adjacent to the city. Here's a part of that poem called Confluence. Lightly on a slope of stone, a trickle sounds, and some small flying insects sip and celebrate the drop of temperature, moisture, puffs of moss in hand-sized pool. enough as cracks conduct through centuries of snow from reservoirs within the mountain rock.

Todd needed to do some research, but he is not the kind of person who just found that in. And I specifically wanted a scientific approach, like I could have read the literature on mountain streams. I really did not know what I was getting into. I was really very innocent, but it wound up that I spent four years, four field seasons, surveying streams with a couple of different teams of scientists. Todd just started showing up at field stations run by the University of California in the Sierras. He talked to whoever was there and pitched himself as an artist working on a public poem, but also as a researcher with his own scientific questions.

And they were really welcoming they had work to do, but they were also really pleased to share what they were doing. He got in contact with a couple other groups, and basically became another member of these teams, helping them carry equipment on three-hour hikes into the mountains, banding frogs in Yosemite, and eventually he found a team that was experimenting with constructing concrete stream channels in the Sierras.

They were as fascinated with what I was doing as I was with what they were doing, but I was really there, like, I was a double agent. I was supporting them in their science, and they were like, I wonder what Todd's going to come up with. Whenever I had a question, I could say, hey, what about this? And they could show me through the microscope what was going on, and then I could reflect that in words and images. The slopes chime gently as a liquid earth flows by beneath the dry,

but here and there the arid and the wet will cross, revealing that which we call moisture, spring, brook, river, flow. Another chance to name and know what surfaces can hide or clarify and what goes on below. After writing the poem, Todd created a custom font that was printed in bright yellow on contact paper, kind of like a bumper sticker, into nine-foot-long strips, about six inches high. It took him in a handful of art school graduates about three weeks to install it on over 6,000 feet of Reno's curbs.

Somebody commented that they came across the piece and they started reading, and before they knew it, they were three blocks out of their way. So that was really what I hoped for was that the work would engage someone in the physical act of walking, of being in the city, and at the same time engage their imagination in the regional environment and the dynamics of how water-shaped landscapes. Confluence will be on Reno's sidewalks until September, and you can check out photos of it on our website. That's at ScienceFriiday.com slash sidewalk poem. I'm Dee Petersmith. And that's it for today's episode.

Lots of folks helped make the show, including Jason Rosenberg, George Harper, Kathleen Davis, Shoshana Bucksbaum, and many more. Next time, Ira checks in on some of the week's news and science. I'm SciFry producer Charles Bergquist. Thanks for listening. We'll see you soon.