Great apes shine light on the evolutionary origins of teasing

Teasing is a fascinating but hard-to-define phenomenon that straddles the line between aggression and play.

New observational research has documented playful teasing in great apes – orangutans, chimpanzees, bonobos and gorillas – suggesting that the prerequisites for humour may have been present in our last common ancestor at least 13 million years ago.

Babies as young as 8 months old are known to playfully tease others with repetitive provocations that often involve surprise. Since language isn’t required, this raises questions about whether similar kinds of behaviour might be present in other animals.

Playful teasing sits on the more playful and less aggressive end of the teasing spectrum. It’s believed to be a cognitive precursor to joking, which draws on social intelligence, anticipating future actions, and recognising and appreciating the violation of others’ expectations.

“Great apes are excellent candidates for playful teasing, as they are closely related to us, engage in social play, show laughter and display relatively sophisticated understandings of others’ expectations,” says first author Isabelle Laumer, primatologist and cognitive biologist at the University of California Los Angeles and the Max Planck Institute of Animal Behaviour in Germany.

Photograph of a female orangutan with her offspring pulling her hair from off camera above her.
Juvenile orangutan pulling its mother’s hair. Credit: BOS Foundation BPI

Great apes tease each other too

The researchers analysed spontaneous social interactions in great apes and observed the teaser’s actions, bodily movements, facial expressions, and how their targets responded to the teasing. They also assessed intentionality by looking at whether teasing was directed at a specific target, if it persisted or intensified, or if the teasers waited for a response.

“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 behaviours that were extremely difficult for the target to ignore,” explains senior author Erica Cartmill, an interdisciplinary scholar focusing on the evolution of communication and cognition at UCLA and Indiana University in the US.

Playful teasing mainly happened when apes were relaxed but was very different from normal play behaviour as it was largely one-sided and rarely reciprocated.

“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,” says Cartmill.

Laumer adds that “similar to teasing in children, ape playful teasing involves one-sided provocation, “response waiting” in which the teaser looks towards the target’s face directly after an action, repetition, and elements of surprise.”

The new paper published in the Proceedings of the Royal Society B is the first to systematically study playful teasing in great apes.

“From an evolutionary perspective, the presence of playful teasing in all four great apes and its similarities to playful teasing and joking in human infants suggests that it may have been present in our last common ancestor, at least 13 million years ago,” explains Laumer.

“We hope that this study raises awareness of the similarities we share with our closest relatives and the importance of protecting these endangered animals.”

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