Do apes have humor? A new study from a team led by Dr. Erica Cartmill shows that great apes playfully tease each other. Learn more in this Stories of Impact podcast.
Humor is often seen as a uniquely human trait, but new research by Dr. Erica Cartmill and her colleagues sheds light on the playful teasing behaviors observed in apes.
These behaviors not only challenge traditional views of animal intelligence but also offer insights into the shared cognitive traits between humans and our primate relatives.
Dr. Cartmill's curiosity about this topic was ignited by a memorable interaction she witnessed between two orangutans while she was doing graduate research on ape gestural communication. In this Stories of Impact episode, she describes the observation that stayed with her throughout her years of interdisciplinary research into the evolution of communication and cognition:
A young ape repeatedly offered a stick to its mother — only to snatch it away at the last second. When the infant stopped, the mother picked up the stick and began doing the same to the baby! Cartmill was intrigued, but didn't know how to study this as a gesture. "In that moment, [the interaction] became a game for me," she says. "It became this beautiful crystallized little gem of an interaction. I really wanted to understand what's going on."
But was it a game? Years later, when she became a professor, her lab was split between research on humans and research on non-human primates, "doing both observational work, as well as doing experimental games — the kinds of games you would play with toddlers." This experience led her, over time, to pivot from thinking about what she'd observed between the orangutans "as a game" to thinking about it "as a joke."
Joking is an important part of human interaction that draws on social intelligence, an ability to anticipate future actions, and an ability to recognize and appreciate the violation of others’ expectations. Teasing has much in common with joking, and playful teasing may be seen as a cognitive precursor to joking. The first forms of playful teasing in humans emerge even before babies say their first words, as early as eight months of age. The earliest forms of teasing are repetitive provocations often involving surprise. Infants tease their parents by playfully offering and withdrawing objects, violating social rules, and disrupting others’ activities.1
Do apes create and appreciate similar moments of incongruity? And do those moments represent a form of humor? In search of answers to questions like these, Cartmill was inspired her to carry out a research project investigating playful teasing among great apes.
"Do apes understand that others can be surprised?" - Dr. Erica Cartmill
In February 2024, Cartmill and her team of cognitive biologists and primatologists shared the results of the study in this paper. The scientists from the Max Planck Institute of Animal Behavior, the University of California Los Angeles, the University of California San Diego, and Indiana University (Isabelle Laumer, Sasha Winkler, Federico Rossano, and Erica Cartmill, respectively) report evidence of playful teasing in the four great ape species: orangutans, chimpanzees, bonobos and gorillas. They found that like joking behavior in humans, ape teasing is provocative, persistent, and includes elements of surprise and play. The authors note that these findings suggest the prerequisites for humor likely evolved in the human lineage at least 13 million years ago.
Dr. Cartmill sees this work as part of a larger approach to understanding diverse intelligences — the multi-disciplinary, open science study of cognition, whether it's found in humans, animals, plants, machines, or anywhere else. "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," she says.
Listen to the podcast with the above player to hear Dr. Erica Cartmill's insights about humor in apes.
Key Takeaways:
The research team identified 18 distinct teasing behaviors: Many of these behaviors appeared to be used to provoke a response, or at least to attract the target’s attention. “It was common for teasers to repeatedly wave or swing a body part or object in the middle of the target’s field of vision, hit or poke them, stare closely at their face, disrupt their movements, pull on their hair or perform other behaviors that were extremely difficult for the target to ignore,” says Cartmill in the press release.
Watch a video released by Dr. Isabelle Laumer and the research team to see some of the playful teaching observed.
Playful Teasing vs Play: Dr. Cartmill and her colleagues differentiate between play and teasing, though that line wasn't always obvious. Teasing, although playful in nature, stands apart from typical play dynamics. Playful teasing is "one-sided, very much coming from the teaser often throughout the entire interaction and rarely reciprocated," explains Cartmill in the press release. "The animals also rarely use play signals like the primate ‘playface’, which is similar to what we would call a smile, or ‘hold’ gestures that signal their intent to play." Playful teasing mainly occurred when apes were relaxed, and shared similarities with behaviors in humans.
Teasing Behaviors Observed: What were some of the actions the researchers were looking at? "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," explains Cartmill. Observations of playful interactions among apes share similarities to the structure of jokes, including a setup and a punchline.
Understanding Others' Expectations: Cartmill notes, "The violation of expectations is a key feature of primate intelligence and plays a role in what is perceived as funny... A lot of forms of human humor, the more sophisticated forms of humor, are built on a shared underlying appreciation for sensitivity, for the violation of others' expectations." One of the key questions she and her team wanted to address with this study is what apes understand about others' expectations. Cartmill says, "Do they understand that others can be surprised? Do they purposefully set up and violate others' expectations? In what ways do they do that?"
Can Teasing be Pro-Social? "One of the big questions was: can teasing be nice? Can teasing be something that isn't just negative? And I think, when I've been talking with people about this study, sometimes I go a little too far, and I only talk about teasing in terms of it can help solidify social relationships... But the take-home message isn't all teasing is nice... A lot of teasing is horrible, leads to bullying. It can have fatal consequences, both in humans and in nonhumans. 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." One of the next questions she wants to address with her studies is: "What is the function of playful teasing when it comes to these social relationships?"
Expanding traditional views of animal intelligence: "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 describe animals in terms of having internal states, in terms of having emotions, in terms of having friendships. Those things were anathema, even 50 years ago," says Cartmill.
Dr. Erica Cartmill is a Professor, Anthropology, Cognitive Science at Indiana University, Bloomington, and Co-Founder/Director, Diverse Intelligences Summer Institute.
1 Max Planck Institute of Animal Behavior, Radolfzell / Konstanz, Press release: https://www.mpg.de/21524011/0208-ornr-do-apes-have-humor-987453-x
Built upon the award-winning video series of the same name, Templeton World Charity Foundation’s “Stories of Impact” podcast features stories of new scientific research on human flourishing that translate discoveries into practical tools. Bringing a mix of curiosity, compassion, and creativity, journalist Richard Sergay and producer Tavia Gilbert shine a spotlight on the human impact at the heart of cutting-edge social and scientific research projects supported by TWCF
