Humor in Apes
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Welcome to Stories of Impact. I'm your host, writer Tavia Gilbert, and along with journalist Richard Sergei, every first and third Tuesday of the month, we share conversations about the art and science of human flourishing. Any sentient, soulful being paying attention to the way humans are treating other humans has been feeling these hard times, and many of our fellow species are experiencing very painful times indeed.

So I hope that today's episode not only brings a smile to each of our faces, but offers a little bit of hope in the darkness. Today we're back with a friend of the podcast, Dr. Erica Cartmill.

You might remember her from past episodes as a leader in the science of diverse intelligences, the multidisciplinary open science study of cognition, whether it's found in humans, animals, plants, machines, or anywhere else. Today we're talking with Dr. Cartmill about the violation of expectations as a feature of primate intelligence, or in more down-to-earth terms, we're talking about funny monkeys.

Actually, monkeys isn't technically right. It's actually apes. What Dr. Cartmill and her fellow researchers have discovered in a study they call the Humor Project is that humans and apes share a lot of traits, including what we think is funny. Here's Dr. Cartmill. She's been thinking about the setup and the gestures of humor in primates for years.

I've always been really interested in animals and I've always been really interested in language. So I was doing my graduate research at the University of St. Andrews and I was studying ape gestural communication. And I was working in different zoos across Europe and the UK and I was watching orangutans at the Durrell Wildlife Conservation Trust or at the time the Jersey Zoo.

I was looking at gestural interactions and there was this beautiful interaction that I didn't know how to study it in terms of gesture. I kind of didn't fit into the scheme that I was looking at exactly, but it really stuck with me. And I came back to it many years later. And so in this interaction, there was an infant orangutan who was hanging on a rope, dangling over her mother. And that mother was

was lying back in a bed of straw, relaxing. And the infant had a stick in her hand and she would reach down with a stick, sort of reach it towards the mother. And then the mother would kind of lazily reach her hand up, start to grab it. And then it would pull it back at the last second before her hand closed on it. And then mother would drop her arm back. She would relax. And then the infant would do it again. I'm going to stick it out to you. Mother reaches, pull it back.

And it was very funny. You know, I mean, it sort of looked like, you know, a mom humoring her child or it's like, okay, I'll do it again. Fine. But what I thought was particularly interesting with this interaction, what really stayed with me was that after a few times of doing this, the infant dropped the stick and I sort of thought, okay, the interaction is over, but then the mother picked it up and started doing it back to the infant.

And it really, in that moment, became a game for me. It became this beautiful, crystallized little gem of an interaction. Dr. Cartmill studied both linguistics and biology as an undergrad. And she couldn't forget that moment, that game, as she began to do research as a postdoc student, and then later when she became a professor.

When I was doing my postdoctoral research, I was at the University of Chicago and I worked on human children and studied how they use gesture, how they learn from others' gestures. When I started as a professor, my lab was split between research on humans, research on non-human primates. And I was doing both observational work

as well as doing more experimental games, the kinds of games you would play with toddlers. So what are they looking at? What are they choosing? Who are they choosing to play with? And my thinking over time had pivoted from thinking about it as a game to thinking about it as a joke.

So it has the setup, right? Do you want to take the thing? And it has a punchline. Just kidding. I'm violating the norm. And in many ways, it does have the structure of a joke, a very simple joke, right? And not a joke that you or I would tell, maybe.

but certainly a joke that a toddler would tell. And I think also it's repetition is something that's very similar to what you see in human toddlers, right? Where they go again, again, I'm telling the same joke, I'm doing the same thing. And it just had this beautiful sort of clean,

Like, you know, it was very simple as an interaction, but it also, you know, had this depth in terms of what it implied about their understanding of the other's expectations.

And so I really wanted to dig deeper and to look for other cases where you might see this kind of behavior. Not only was Dr. Cartmill interested in where else she might observe that behavior, she also wanted to answer other big questions. What is it that makes a joke? We really, I think, came up with the answer that it's something about the violation of expectation. And it might actually be the setting up and then violating of those expectations.

And in the setting up and violating of expectations, something that even maybe better fits that definition is this idea of playful teasing.

And so I think the big question that we were trying to address is what do apes understand about others' expectations? Do they understand that others can be surprised? Do they purposefully set up and violate others' expectations? In what ways do they do that? You know, we knew that they did this sort of offer and retract behavior.

But we wanted to see what other kinds of things they did. We didn't know how rare it was. We didn't know whether this is something that only occurred between mothers and infants, or if it occurred between siblings, or if it occurred between adults. Dr. Cartmill wanted to focus on apes in order to lay a foundation for studying animal humor and playful teasing. I would call it kind of a building block that underlies what in humans becomes humor.

Dr. Cartmill and her colleagues designed a series of studies to look at this teasing behavior. We designed a whole series of studies to look at this. And so we used existing video of great apes in zoos interacting with one another and tried to find instances where there was an affiliative social interaction or something that was not explicitly aggressive. So there's no fighting, there's no sort of threat displays.

but it also isn't grooming or sleeping together. So something that has a little bit of energy to it, but doesn't have any aggression. And we wanted to see sort of out of that set of things, what kinds of behaviors might fit our increasingly focused idea about expectation violations.

You know, I think it's very hard to demonstrate that someone is in fact violating an expectation. So what we ended up using was this idea of provocation. And so we're very interested in when apes were provoking other apes, but doing it in a way that didn't lead to violence.

So this wasn't about a dominance display. This wasn't competition over resources. And of course, it's really hard to say like, oh, what is teasing? Well, it's provocation. Okay, well, what's that? And so our working definition for that was something that becomes increasingly hard to ignore.

So there's some beautiful interactions where, you know, one ape will come over and stare at another one. And, you know, the other ape is like ignoring them and doing something. And then they'll lean closer and then they'll put their face right in front of the other one's face. Okay, well, maybe I can still ignore. And then we'll start poking them. And so it's just something that escalates and becomes harder and harder to ignore.

Dr. Cartmill acknowledges that there may be differences between her study of the behavior of animals in captivity versus what they might find in animals in the wild. One difference you might expect to find between captivity and the wild is simply in the rate of these behaviors. It might be that in captivity they're happening more frequently because the animals are spending less of their time foraging, they're spending less of their time traveling. We see that if we're just looking at play behaviors, right? Animals in captivity are spending more time playing.

They're also spending more time bored, you know, in the same way that two siblings in the backseat of a car on a cross country road trip are going to spend more time poking each other and, you know, irritating each one another. You might see that apes are spending their time entertaining themselves by provoking others in captivity.

I do think we'll see the behaviors in the wild, but they might be things that you don't see every day and maybe are clustered around certain contexts or certain periods of the day where there's not foraging, where they really have more downtime. What behaviors did the researchers identify as teasing? So teasing behaviors included things like

pulling on hair, poking, hitting, somersaulting into, I think we called it a body slam, as well as waving an object in front of another, hitting another with an object, you know, a wide range of different kinds of behaviors. Some are visual, some are tactile. It was more about how those behaviors were used, right? That they were used in ways that often contained an element of surprise and

They were used in interactions that were asymmetrical, where one ape was deploying a series of behaviors towards another ape who was largely ignoring them. And then you're often seeing the apes follow it up with persisting, you know, producing the same behavior again, or elaborating, changing to a different behavior or making the behavior they just did stronger or bigger, more salient in some way.

So I think one of the big goals of the study was simply to argue that playful teasing is a real behavior. It's potentially very interesting in terms of social cognition and more people should pay attention to it. One of the big questions was, you know, can teasing be

nice? Can teasing be pro-social? Can teasing be something that isn't just negative? And I think, you know, when I've been talking with people about this study, you know, sometimes I kind of go a little too far and I only talk about teasing in terms of, oh, it's, you know, can help solidify social relationships and everything. And the take home message isn't all teasing is nice, right? A lot of teasing is horrible. It leads to bullying. It can have fatal consequences, both in humans and in non-humans.

But what I wanted to do was to widen the discourse around teasing and say not all teasing is bad. A lot of teasing is playful, is playfully provocative. You think about the teasing that happens between close friends or between siblings on good days rather than bad days or between two people on a date. I think flirting is definitely a form of playful teasing where you're trying, you're pushing someone's buttons a little bit

but in a way that demonstrates the strength of your relationship, in a way that might test the strength of your relationship, and I think ultimately in a way that might increase the strength of your relationship. And those are really the next questions that we want to ask on this project. It's like, what is the function of playful teasing when it comes to these social relationships? One of the things Dr. Cartmill found that she didn't expect...

Teasing behavior in apes is not limited to infants and juveniles. What was surprising was when you got that role reversal, when the adult did it back to the infant. And there were some other interactions like that in the later study that I just thought were beautiful. So in one of them, there's a juvenile who's trying to, you know, has a little, has a stick and is using it to get food out of a feeder.

I don't know whether it was peanut butter or honey or something, but you know they're kind of taking their little stick and poking it into the holes and there's an adult who is lying down underneath the feeder and

with low intensity, keeps reaching up her hand and blocking the infant at the last second. You know, it's sort of like, "Ah, I'm foiling you." Like, "Oh, you're gonna go in there?" "No, you're not." And then the infant tries somewhere else. "No, you're not." And it was almost like whack-a-mole, you know? It's like, "Okay, I'm gonna keep, you know, blocking wherever the thing comes." And what I thought was really interesting was that they weren't competing for resources. The adult wasn't trying to feed herself. There were lots of other sticks. She wasn't trying to get the stick.

you know, she was bored and she was messing with the infant. And I just, I thought it was so amusing to see, you know, this

adult sort of entertaining themselves by, again, sort of benignly annoying the infant by thwarting them. I really enjoy, maybe it sounds perverse, but I really enjoy the teasing interactions where you see one individual thwarting another's attempt at something. But they're doing it, you know, again, in a low intensity way. They're not competing over resources. These are happening within close social relationships.

And so, you know, it's the same kind of way that you might playfully thwart, you know, a spouse. I think it's difficult not to read too much into these interactions. And so we're starting from, you know, just describing the behavior and raising questions about what are the possible reasons that apes could be doing this.

a lot of the focus in our developing a coding system was trying to look for things that would work across species. Those are things that can be applied, you know, that will differ from species to species, but that can be applied regardless of the species that you're looking at. Dr. Cartmill and her colleagues wanted to distinguish between play and teasing, though that line wasn't always obvious. When you see the behaviors, they are different from your expectations about play, right? They really look like teasing.

But it's very hard to come up with criteria that draw a clean line between teasing on the one hand and play on the other hand. You know, I think teasing is very interesting because it exists in this gray area between aggression and play. It has elements of aggression. You know, it's annoying. It invades other space. Others often react by either ignoring or moving away or

But it also contains a lot of elements of play, right? It sometimes involves play faces. It happens within close relationships. It happens during moments of boredom and kind of relaxed environments. And it doesn't result in aggression. So it is that gray area. And I think that makes it really hard to study, you know, as a scientist. But I also think that it makes it hard to navigate as an ape, right?

or as a child, or as, you know, another animal who's involved in a playful teasing interaction. And that difficulty is exactly why I think it's fascinating, because it is a difficult social situation to be in. You have to read the other's behavior, you have to read the other's intention. And I think that that's what gives it this richness, and, you know, might make it

a really unique opportunity to look at the ways in which animals or humans are predicting others' reactions.

and maybe practicing their prediction of others' responses to their behavior. So I think it gives it this, you know, the beauty is in the difficulty, I think. It's pretty easy to distinguish it from successful play interactions, right? It doesn't result in reciprocal behaviors. It's highly asymmetrical. Play is not.

It almost never results in two apes wrestling around together in a kind of high-intensity play, which is what often results from play requests. The study doesn't just reveal more about animal behavior, and it doesn't just illuminate another way humans and apes behave similarly. It widens scientists' perspectives about the sentience and the souls of all animals.

It's really important to build our analyses from observable behaviors. But I do think that those observable behaviors are driven by internal states. And I think that we're finally in an age where internal states in animals can include things that aren't just animals.

hunger and fear and, you know, and tiredness that, you know, I think as scientists, we're becoming more open to the possibility that animals have friendships, that animals have preferences, that animals might do certain things because they're enjoyable, not because they have an immediate benefit in terms of their survival.

And I think we're finally coming to a point where within the scientific literature, we're able to

to describe animals in terms of having internal states, in terms of having emotions, in terms of having friendships. Those things were anathema, you know, even 50 years ago. Motivation was really thought about as, is there a positive stimulus? Is there a negative stimulus? Is there a hormone that's triggering this behavior? You know, it was very mechanical and it was, you know, really strongly influenced by behaviorism.

While the study was designed to look at humor in animals, Dr. Cartmill believes it gives us insight into human humor as well. I think it's an exciting time to be a scientist who looks at animal behavior because I think that this world of cognition and emotion is becoming more and more open to animal researchers. One of the things that this study has opened up for me

is the possibility that a lot of forms of human humor, the more sophisticated forms of humor, are built on a shared underlying

appreciation for, sensitivity for, if you will, the violation of others' expectations. That at their core, jokes are really about doing something outside the normal, doing something that violates, that surprises,

that shifts perspective. And I think that those shifts, those violations, those moments of surprise are present in playful teasing. I think they're present in human infants from their first year of life

They're present in our closest relatives, the great apes. I think they're probably present in other social animals. We just need to look at them in a systematic way to really see. And so I think there's some really interesting questions that we can ask in terms of, you know, where does teasing occur?

what is interesting about it, what's exciting about it. And that might provide some insight into even more sophisticated forms of human humor in terms of, you know, what are the seeds, what are the building blocks that human jokes are built on.

Dr. Cartmill sees her work as part of a larger, multidisciplinary approach to understanding diverse intelligences. I love talking about diverse intelligences. I think the S on intelligences is really important, both in terms of

capturing the breadth of species and minds, right? This would include things like artificial intelligences, different kinds of models of the mind, but also in terms of different kinds of intelligence, right? So I think that diverse intelligences isn't just about learning or it isn't just about pattern recognition. It isn't just about prediction. It's being open to the possibility that understanding

navigating, predicting and changing the world might happen in different ways at different times, in different species, different ages and through engagement with different technologies. And so I really love this

this paradigm as a way to study the mind because it allows for such a diversity of approaches on the one hand, but also a diversity of manifestations of what it means to have intelligence, what it means to be an intelligent behavior. And I think by having this broader perspective, you're surfacing really interesting

kinds of behaviors. You're thinking about differences, potential differences between species or between individuals or between emotional states of the same individual, of the same species. But I see diverse intelligences as being a very generative, very rich environment to

to create new ideas about the mind in terms of the hypotheses that it's creating. And I think about diverse intelligence as opening many more doors than it closes.

Before we close for today, we want to acknowledge the passing of Dr. Daniel Kahneman, who was featured in our recent episode about adversarial collaboration. Dr. Kahneman died on March 27th at the age of 90, after a long career as a writer, psychologist, and economist. We are so glad we got to share some of his work with you. He was a giant in the field of science, and he will be missed forever.

We'll be back in two weeks with another episode. In the meantime, if you enjoy the stories we share with you on the podcast, please follow us, give us a five-star rating, and share this podcast with a friend. And be sure to sign up for the TWCF newsletter at templetonworldcharity.org. You can find us on Twitter, Instagram, and Facebook, and at storiesofimpact.org.

This has been the Stories of Impact podcast with interviews by Richard Sergei. Written and produced by TalkBox Productions and Tavia Gilbert. Senior producer Katie Flood. Assistant producer Oscar Falk. Music by Alexander Filipiak. Mix and master by Kayla Elrod. Executive producer Michelle Cobb. The Stories of Impact podcast is generously supported by Templeton World Charity Foundation.