- Cracking a good joke is no laughing matter, but the complex cognitive abilities that underpin humor have so far been studied mostly in humans, with our great ape cousins going largely overlooked.
- Now, a new study reports playful teasing behavior — a precursor to joking — in small groups of chimpanzees, gorillas, bonobos and orangutans.
- The study is the first to define playful teasing as a distinct behavior separate from play in great apes and describe its various forms.
- The findings suggest that the cognitive requirements for joking and playful teasing evolved at least 13 million years ago in ancestors common to humans and great apes.
Being silly and indulging in humor may sound easy, but our brains need to do a lot of heavy lifting to pull it off. Landing a joke requires recognizing what’s socially acceptable, being spontaneous, predicting how others may react, and playfully violating some social expectations. Until now, research on the complex cognitive abilities that underpin humor has focused primarily on humans, while other species are understudied.
In a recent study, published in the journal Proceedings of the Royal Society B, researchers present the first evidence of playful teasing behavior in great apes.
Thought to be a precursor to joking, playful teasing involves the teaser performing provocative actions such as poking, hitting or pulling on a body part with playful rather than aggressive intent.
Although primatologists in the past, including Jane Goodall, have anecdotally described great apes as being silly and pestering others, this is the first study to systematically describe the behavior in zoo-housed chimpanzees, gorillas, bonobos and orangutans.
“Playful teasing is interesting because it’s really getting at that teasing component — an individual motivated behavior that is trying to create something akin to joking or being silly,” said primatologist Ammie Kalan from the University of Victoria, Canada, who was not involved in the study. “One of the things that I think is cool with this paper is that they’re purposely trying to set [playful teasing] apart from play.”
The researchers studied videos of social interactions between the members of each ape group to identify events that met predefined criteria of teasing and play, such as the teaser initiating the interaction or gauging the recipient’s response. While the group sizes varied, they all had at least one juvenile, aged 3-5 years, on whom the cameras focused.
Playful teasing comes in many forms
The study identified 18 observed behaviors that the researchers categorized as playful teasing, such as poking, pulling on a body part, hitting, and body slamming. The 75 hours of video they analyzed contained 142 such events. Juveniles initiated most of these interactions and often displayed more than one behavior until they caught the attention of their target, primarily adults.
“They were doing an action, let’s say poking or jumping on someone, and then they would always look into the face of the target,” said lead author Isabelle Laumer from the Max Planck Institute of Animal Behavior, Germany. She posits that this “response-looking” behavior, characteristic of play teasing, is to calibrate their behavior so the interaction doesn’t escalate into a fight or enrage the adults. “I was surprised and fascinated by it.”
Unlike play, which is highly reciprocal and involves signals like hand raising, head butting and play face, playful teasing was one-sided from the start. In more than nine out of 10 interactions, it was initiated by the teaser, and only a quarter of teasing events resulted in play. In nearly a quarter of interactions, the teaser surprised their target by approaching them from behind.
Juveniles mainly targeted adults for teasing, and they picked on specific individuals. “It was actually very intentional behavior because they approached one specific individual,” Laumer said. “It was not random.”
Although the study looked at just one group of each ape species, the observations showed that all teased similarly. However, since the sample size was very small — one juvenile in each of the groups, and only four groups considered — the researchers caution against generalizing this observation across species and age groups.
“All the playful teasing they’re describing is centered around a single individual in each group,” Kalan said. “That means you’re already looking at a very different demographic than what you would encounter in a natural grouping setting.” In the wild, she said, a typical ape group would have more than one juvenile, and there might be a lot of playful teasing between juveniles, which helps develop proper socialization behavior.
The findings shed light on the evolutionary history of humor and suggest that the common ancestors of apes and humans, who lived 13 million years ago, likely had cognitive abilities to playfully tease.
The study adds to a long list of characteristics humans share with great apes, such as the ability to laugh, grieve, play and empathize, which Laumer said might add momentum to conserving them. “Great apes are critically endangered, so finding another ability that is shared [with humans] puts the attention on them,” she told Mongabay, “For me, that is a very important aspect of the study.”
Banner image: Two chimpanzees interacting playfully. Image by Herusutimbul via Wikimedia Commons (CC BY-SA 4.0).
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Citations:
Laumer, I. B., Winkler, S. L., Rossano, F., & Cartmill, E. A. (2024). Spontaneous playful teasing in four great ape species. Proceedings of the Royal Society B: Biological Sciences, 291(2016). doi:10.1098/rspb.2023.2345
Cordoni, G., & Palagi, E. (2011). Ontogenetic trajectories of chimpanzee social play: Similarities with humans. PLOS ONE, 6(11), e27344. doi:10.1371/journal.pone.0027344
Eckert, J., Winkler, S. L., & Cartmill, E. A. (2020). Just kidding: The evolutionary roots of playful teasing. Biology Letters, 16(9), 20200370. doi:10.1098/rsbl.2020.0370
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