Feb 18, 2024 - Science

Great apes' playful teasing points to origin of humor

An orangutan pulls another orangutan's hair

Photo: BOS Foundation BPI

Body-slamming, hiding, hitting, poking, offering — and withdrawing an object, stealing, tickling and other teasing behaviors are documented across four great ape species in a new study.

The big picture: Teasing reflects social understanding and a sense of another individual's expectations — cognitive capabilities that are also building blocks for joking.

  • The presence of playful teasing in several ape species suggests the trait was "most likely inherited from our last common ancestor" and that the precursors for humor evolved at least 13 million years ago, the researchers report.

What they did: The team analyzed 75 hours of video of four great ape species — chimpanzees, gorillas, bonobos and orangutans — at the San Diego and Leipzig zoos. They focused on apes between 3 and 5 years old and, using a coding system they developed, identified 18 playful teasing behaviors.

  • These often involved attention-getting, repetition, or escalation. And unlike playing, they were one-sided, the researchers write in the Proceedings of the Royal Society B.
  • At the core is something surprising or provocative — in a loving way, says study co-author Erica Cartmill, an anthropology professor at Indiana University.
  • "That unexpected moment, that pivot, that violation seemed to be what made that interaction really special."

What's next: Cartmill says the goal of the study was to "lay the foundation for a science of playful teasing."

  • She hopes to inspire others to collect data on the behavior, including citizen scientists.
  • "I'd love to get videos of people's parrots, dogs, rabbits and cats all provocatively" interacting with one another.
  • "Once you realize that it's its own kind of behavior, you're going to see examples of it everywhere."

Editor's note: This story has been updated with the correct name of Indiana University.

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