Learning From Handy Primates

Learning From Handy Primates

[introductory music]

Voice 1: What makes us human?

Voice 2: A very beautiful day.

Voice 3: Little termite farm.

Voice 4: Things that create wonder.

Voice 5: Social media.

Voice 6: Forced migration.

Voice 1: What makes us human?

Voice 7: Stone tools.

Voice 8: A hydropower dam.

Voice 9: Pintura indígena.

Voice 10: Earthquakes and volcanoes.

Voice 11: Coming in from Mars.

Voice 12: The first cyborg.

Voice 1: Let’s find out. SAPIENS: A Podcast for Everything Human.

Eshe Lewis: My friend David lives in Lima, Peru. One day, he’s cooking for us. He’s making a pork adobo, which is the savory meat stew. While he preps, I stand next to him and do what I do best in a Peruvian kitchen: chat up a storm. So David’s chopping garlic, and he asks me to open a can of peaches. So I pull open cabinets and drawers. I’m looking for a can opener, but I can’t find one. I can hear his chopping slow down as my search continues, and finally he stops and just asks me what I’m looking for.

When I reply with “a can opener?” David rolls his eyes and laughs: “Why do northerners have so many tools?” Then he pulls a smaller knife out from the drawer closest to him, and he swiftly opens the can. Now my relatives from the Caribbean have also asked this question: “Why do you have so many tools for tasks a knife can handle?”

It’s a good question, and the answer leads us to other questions: What counts as a tool? Who uses them, and why?

Today I’m speaking with researcher Kristy Graham about tool use, starting with primates. Kirsty is an animal behavior researcher, who studies how nonhuman primates use gestures to communicate. I spoke with Kirsty to better understand tool use in apes and what that might be able to tell us about tool use in humans.

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Eshe: I’ve heard that over the past decade, scientists have debated the definition of “tool.” And it sounds like an important question to answer when you’re looking at which animals use tools and when our ancestors first used them. So can you give me a definition of what a tool is?

Kirsty Graham: I would define a tool as an object that an individual can pick up and manipulate and use to achieve a particular goal. And I think that’s where some of the debate comes in. If you’re smacking something against the ground to break it open, is the ground a tool?

Eshe: So what does tool use mean for primates like chimpanzees and related species, closely related species, like bonobos? What does that look like for them?

Kirsty: Other primates often use tools to solve foraging problems. So chimpanzees will fish for termites using long sticks. Some chimpanzees even have sort of a toolkit of sticks that they’ll use to get at the termites if they’re underground. They might have a thicker stick to break through the ground and then a longer, thinner stick to fish for the termites.

They break nuts open with stone tools or sometimes use moss or crushed leaves to dab water and use it to drink. I would say mostly chimpanzees are using tools to get more nutrients in what are sometimes quite changeable environments. Maybe there aren’t always the figs fruiting that you’d like to eat, but there’s a termite mound over there, and you need a tool to get at that. So it’s often to access difficult food sources.

Eshe: How does that compare to tool use for humans? Do you see any overlap there in what you’re seeing between primates and other primates and how we might think about how we use tools?

Kirsty: While the majority of tools and other primates are probably to solve foraging problems, humans use tools in a huge diversity of ways. We obviously do use tools to pick, plant, and to store plants. And we’re doing a lot of foraging tool use as well. We’re solving problems all the time with tools. It’s such a fundamental part of how we work. Like, I’m holding a phone in my hand. I’m on a laptop. I’m wearing headphones. These are all objects that I’m using to achieve this particular goal. And so I think maybe there’s a difference in the sort of imagination space of goals that we are achieving compared to other primates where it’s very often a foraging need that’s being met.

Eshe: And what’s the connection, rather, between tools and communication in bonobos and in chimpanzees?

Kirsty: There are also tools that we use to communicate and that other primates use to communicate. I’m thinking things like drums. So chimpanzees and bonobos will drum on the buttresses of trees, on those really long, extended root systems that grow above ground. They have really good resonance. And so they’ll communicate with one another over long distances by banging on trees, which, again, is difficult within the definition of tools because they’re not picking up the tree and using it in that way. So you might consider that an object to use in communication.

They do drag branches as well, in display, so often when they’re traveling or tensions are a bit higher, they’ll pick up a loose branch and drag it across and run across the ground. A lot of object use and a lot of tool use and communication comes in these bigger displays where they’re making more noise, attracting the attention of more individuals. They’re dragging branches. They’re throwing rocks. They’re slapping the ground. They’re drumming on buttresses. They’re engaging in a bigger performative space.

There is a particular gesture type that’s a more discreet way that they use tools, and that’s leaf clipping, and this is often when they’re flirting with others. So it’s a “come-hither” gesture. They’ll pick the leaves; sometimes they’ll pluck leaves off with their fingers, but often they’ll tear the leaves between their teeth. And it makes this kind of ripping sound. And so it’s a very particular gesture that they’re using a tool for.

And so I think there’s probably going to be some people listening to this thinking, “OK. Is it communicative tool use or is it tools used for communication?” I think there’s an ontological argument there. But they do use objects quite readily in their communication.

Eshe: OK. So I guess my next question has to be what kind of messages or information do, say, chimps have to share with each other? It sounds like there’s a lot of communication going on. What are they talking about?

Kirsty: Over these longer distances, with chimps and bonobos and other apes, it’s often about communicating where they are and having this sense of group cohesion over long distances because their groups will split up into smaller parties to forage and then come back together. So they’re keeping track of each other.

They also do a lot of close-contact communication. And I think that’s particularly where gestures come in handy. They have gestures where they’re asking for food or they’re asking to start playing or they’re asking to groom the bits out of each other’s fur. They use gestures to request sex. They have a really good one that’s a hand fling. So if you think of shooing someone away: Chimps and bonobos will use that gesture for the same outcome, to tell others to move away from them. So these gestures are used in one-on-one or smaller group social interactions to request other individuals to engage with them socially in some way.

Eshe: I’m now wondering if there is anything you know, or have seen, about primates communicating across species? There’s all this communication between chimpanzees, between their groups, but do we know anything about whether primates of different species can communicate with each other? Is there any crossover there?

Kirsty: In terms of vocal communication, there is some evidence from different monkey species of cross-species communication, understanding one another’s alarm calls. It’s really useful. A lot of birds do this, too. It’s really useful if you can learn the alarm calls of other species because then they’re noticing threats, and you can pick up on that, too. So there is some evidence there. In terms of their gestures, there is not much direct evidence whether different primates understand each other’s gestures.

There is a particular site in the Republic of Congo where there are gorillas and chimpanzees who live in an overlapping range. There’s a lot of potential for research there because there are very small pockets where gorillas and chimpanzees overlap where it would be possible to study in the wild. But if we look at the gesture types that they’re using and compare across species, chimpanzees and bonobos share over 90 percent of their gestures.

We think that gorillas and orangutans probably also likely share at least 80 percent of their gestures. And my research group in St. Andrews is putting together a huge comparison across all of the great ape species—also including human infants, who seem to use some of the gestures, too, before they start learning gestures and language from other people. So, in principle, we think that they would be able to communicate with one another given this huge overlap in the gesture types. But there is currently very little direct evidence.

Eshe: I have some more tool questions for you, though I feel like I could listen to you talk more about gestures for a significant amount of time, and so thank you for sharing. I wanted to know how tools are different from technology. Do you have any insight on that?

Kirsty: So you might pick up a stick and use it directly as it is, like in the branch-dragging that the chimps do: You see what’s around, you pick it up, and you run with it. It’s the same with the stones that they use. There may be some thought that goes into selecting a tool: You might select a bigger stone or a flatter stone for nut cracking, but you’re not modifying the stone itself. But then you get into evidence of tool modification: picking up or taking a stick off a tree or a sapling, stripping the branches off that, and then maybe chewing the end of it to make a kind of brush to dip for honey or something.

So we’ve got this range of tool behaviors that we see in other species that range from using an object as it is through modifications of objects in specific ways. Then we also get into potential use of objects to modify other objects, which is the more complicated end of things. This sort of modification and multistep processing gets more into technology, I think.

Eshe: I’m interested to know about how technology evolves and spreads and changes. This is something we talk about in different environments and different contexts. And I’m wondering if chimps, say, keep up their tool use, can we expect to see a chimp-made smartphone? Or I’ve heard that they make beds. Can we expect a chimp-owned mattress company? What do we know about how tool use evolves and technology evolves in primates?

Kirsty: There are a couple of neat studies showing new tool use, or new object behaviors, and how they spread through social groups. I’m thinking of one at Budongo [Forest Reserve, Uganda] where the chimp group had used leaves to sponge water and drink it, and they changed to using moss, and the researchers were able to observe the first chimp to use moss, and then who had seen her and how then it spread through their community.

There’s another example from, I think, Chimfunshi, which is a sanctuary [in Zambia] where one of the chimps started putting a piece of grass in her ear. And this also spread. And so the other chimps who had seen her do this started putting a piece of grass in their ear, and then it stopped again. So it was almost like a fad or a trend with this grass in the ear. So we know that they can observe other chimps making these tool decisions and then pick up and use those tools themselves.

I think one of the evolutionary questions is, “What is the need that is being met by this tool?” So as I said earlier, the apes seem to be using most of their tools to meet foraging needs. Fruiting seasons are variable. Foods are available at different times. If you can get access to termites or if you can get access to honey or if it’s a dry season and you can get access to water—the tools that they currently use are solving these very specific foraging needs. And it just has to be good enough to meet those needs.

And so I think that’s one of the evolutionary questions: “What problems arise that need a more complicated toolset to solve?” Because as long as a nest made out of folded tree branches is comfortable and safe and good enough for the chimps, they’re going to keep building the nest in the trees that is comfortable and safe and good enough for the chimps. And it’s not until there’s a need where they all have this particular-shaped spine and they need the memory foam in the nest, right [laughs]? So it’s thinking about the particular problems that arise that can’t be solved with the tools that they already have.

Eshe: Is there any way that humans have changed the way we currently use tools or kept because of what we have learned from primates?

Kirsty: I’m not sure if people have changed the way that we use tools because of what we’ve learned from primates. But I think the way that we study the history of tools has changed somewhat because we see so many perishable tools being used by other primates.

A lot of the chimpanzees are building these nests that deteriorate. They have stick tools that they use for termite fishing or to scare the galago out of the hollows of their trees—they are using a lot of stick tools or leaves or branches, and those will deteriorate over time.

And so if we think about the history of tool use, we think about stone tools because stone tools survive. But seeing how widespread these perishable tools are in other species and then reflecting on ourselves and thinking, “Oh yes, a lot of the tools and technology that we use are also perishable and would also degrade and also wouldn’t leave this historical record.” And thinking about “What are those steps for perishable tools as well?” So not just thinking of ourselves as stone tool users or as bronze tool users or as iron tool users but to think about all of the perishable tools that come along with that.

Eshe: That really broadens the landscape in terms of imagining what our ancestors might have used as far as tools are concerned. If we’re able to think beyond metals that might have lasted or stones, we’re really opening up the world of possibility to think about what might have been useful or innovative for us that we just don’t have a record of today.

Kirsty: If you have an axe-head, you might need an axe-handle. What are you chopping the wood down for? Is it for shelters? Is it to make other things? Is it for boats? There are so many other things that what is left is maybe the axe-head. But there’s this whole story of perishable tool use and technology around it.

Eshe: Is there any tool that you have seen bonobos or chimps use that you think humans should use?

Kirsty: So bonobos are not prolific tool users. They can use tools and be taught to use tools in captivity, but in the wild, they don’t bother with it, except they will fold up a leafy branch and hold it over their heads to make an umbrella. And if it is raining hard, and I have forgotten my umbrella or it is inadequate for the amount of rain, I will sometimes copy them and also fold up a leafy branch or find a nice larger leaf to cover for an umbrella. Yeah, in a pinch, I would copy the bonobo umbrella use.

Eshe: We’ll hear more from Kirsty about bonobos, chimps, and human tool use after the break.

[break with SAPIENS ad]

Eshe: I’m wondering how working with nonhuman primate technology or communication and tools changes the way you think about human technology and its possibilities? You talked a bit about that in the past—using chimps as information to think about what we might have used in the past that we just can’t see now. But is there anything that you think about in terms of possibilities for a future? Are there any jump-off points there?

Kirsty: I used to have a Google Scholar alert set up to tell me when new gesture papers would come out, and I ended up turning it off because all of the new gesture papers are about digital gesture technology. And it’s interesting to be in this overlap of communication and tool use or technology because I think there’s a lot to do with not only how we communicate with one another but also how we communicate with the technology that we’re creating.

Gesture obviously is so important to other primate species. It’s something that is deeply important to us and that has coevolved with our language and that we continue to use to help us think and process things. And as we build new programs, gesture is coming along with that. I don’t know that it’s specifically using ape gesture as a way of training a gesture AI. But I think it’s the way that we have this continuous story from primate gesture, including human gesture, into how we’re now thinking of including gesture in our technologies to continue to make them work for us in a way that is more intuitive and accessible for us.

Eshe: Can you give me an example of that?

Kirsty: When you use Microsoft Teams or Zoom or other video conferencing technology, they’re now starting to build in ways of recognizing when your hands are moving and to use those as reactions and things. So that’s a really basic example of how we’re teaching software or teaching programs to recognize gesture.

I think there’s going to be a lot more space for then taking gesture technology and formalizing it for language—sign languages as well, which will be a huge boost in making technology more accessible, to be able to access using sign language as well. And I want to be clear that I’m not equating sign language with gesture but that the technology that was used for gesture might then be useful for sign language transcription and access to different programs.

Eshe: How has this work that you do impacted the way you think about tool use or communication in your own life?

Kirsty: I have done several stone tool workshops to figure out what it’s like to have to make all of these things your own. And I have tried to fish for termites using a stick, and I have tried all of these different tools that are posited as the “base tools”—like a stick to fish for termites or hitting a stone against another piece of flint—which are things that everything else is built on. And it does work, but you have to put in a lot of effort to be good at it.

And I think it gives us an appreciation for how many of the tools and technology that I use that I could not produce. One of my hobbies is fiber craft. So I started learning to crochet and learning to knit, and then I started learning how to spin the wool. And I have a friend who has some sheep. And so after they had been shorn, I washed the wool, and I spun it, and the next step that I would love to learn how to shear the sheep.

It’s this sense of seeing the process from end to end, which is maybe possible in some particular tools. I can see how the chimpanzee has gone from this stick, stripping it, chewing at the end, using it to dip. OK, I can learn this process. It gives me a huge appreciation for all of the tools and technology that I love and could not do without and also have no ability to produce myself.

Eshe: Asking you that was probably because I was heading in the same direction. I am learning to knit again and just this idea that so much of our clothing is knitted fiber fabric, right? And you just take it for granted. And then when you’re sitting there looking at the stitch and crying your way through some sort of failed, warped sweater, you’re like, “This is actually a skill that takes time to do. And I will never take this for granted again.” And so “It’s just a stick, and it’s just being dipped.” But there’s an art to this that we may take for granted because we think we’re better than chimps, smarter sometimes. There’s that sense that we know more. And so it sounds humbling to really have to go through it yourself and take some time to honor that.

Kirsty: Yeah, we benefit so much from this cumulative culture where, over so many years and so many generations, we have maintained and built on skills to create specific technologies where no one person is building the whole laptop, but it gets built because there are enough people within the process who know that particular skill to create that particular component of it. It’s just such an incredibly connected production process that really changes how we engage with tools and technology and what’s available to us.

Eshe: I’m wondering what the most interesting concern or thought from your work that you would like our listeners to take away from all of this?

Kirsty: I would like listeners to take away that apes are doing a lot of really cool stuff with tools and with their communication, and this cognitive toolkit is really very impressive. They’re solving social problems. They’re solving physical problems. At the same time, it’s what is good enough for them. I think that’s the theme that really comes through. And when I’m thinking in terms of how do we explain how these things evolved, there isn’t an end point. There isn’t some goal on the horizon: that the chimps will perfect the termite fishing and will then set up these little termite farms, and then they’ll invent little tractors. And that other species can live in very changeable environments. They live in social groups where it’s really important to keep track of who’s done what to who and make sure that you’re maintaining those relationships.

And what we’re doing currently is good enough for us, and we’re figuring out not why we’re better than them or why our tools are so much better or different … I guess that’s the question: “What happens differently that we have this huge expansive tool use and technology” rather than “Why are we better than chimps and bonobos?”

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Eshe: This episode was hosted by me, Eshe Lewis, featuring Kirsty Graham. Kirsty is a research fellow at the University of St. Andrews in Scotland.

SAPIENS is produced by House of Pod. Cat Jaffee and Dennis Funk are our producers and program teachers. Dennis is also our audio editor and sound designer. Christine Weeber is our copy editor. Our executive producers are Cat Jaffee and Chip Colwell. This episode is part of the SAPIENS Public Scholars Training Fellowship program, which provides in-depth training for anthropologists in the craft of science communication and public scholarship.

SAPIENS is an editorially independent podcast funded this season by the John Templeton Foundation with the support of the University of Chicago Press and the Wenner-Gren Foundation. SAPIENS is part of the American Anthropological Association Podcast Library. Please visit SAPIENS.org to check out the additional resources in the show notes and to see all our great stories about everything human. I’m Eshe Lewis. Thank you for listening.