Great apes like teasing each other – which may be the origin of humour

Bonobos, orangutans, gorillas and chimpanzees all tease, tickle and steal from their mates as a form of playful flirting. Understanding the mischievous behavior of these monkeys may help biologists understand the origins of humans’ sense of humor.

Previous studies have found that chimpanzees may engage in torturous teasing, or harassment, to strengthen their hierarchical position. But when the right balance of enjoyment and aggression is broken, flirting can be a form of play and entertainment, says Isabel Laumer at the Max Planck Institute of Animal Behavior in Germany.

“Until now, the playful aspect of teasing has not been systematically studied,” she says. “So our goal was to identify and create a standard for playful flirting in monkeys.”

To do this, Laumer and his colleagues collected videos of five species of great apes: bonobos (Pan PensixSumatran orangutans (I put abelii.), western and eastern gorillas (Gorilla Gorilla And Gorilla Beringi) and chimpanzees (Pan troglodytes). There were a total of 34 monkeys, all housed in the zoo.

From 75 hours of video footage, the team documented 504 social interactions between individuals. Of these, 142 were classified as playful teasing incidents, including 18 involving behaviors such as hitting, hitting, hair pulling, obstructing movement and stealing.

“Teasing is characterized by an aggravating factor,” says Laumer. “It usually comes from a teaser and is often unilateral, with a lot of repetition.”

The researchers found that the taser looked directly at its target’s face after an action, suggesting that the taser anticipated a response. When there was no response from the target, the tease would usually escalate the teasing, for example by tapping them more.

One of the most important signs that the flirting was playful, rather than hostile, was that it usually took place in a calm, relaxed environment. “People were comfortable during the affair,” Laumer says.

Stealing cases were considered playful when the object offered no obvious benefit to the tease or if they lost interest in it shortly after pinching it.

“We find that playful teasing is present in all four great apes,” says Laumer. Like play in general, this behavior can be useful in building relationships among group mates and even testing social boundaries, she says.

Laumer added that the last common ancestor between humans and other great apes may have engaged in playful banter, which could have been a precursor to our penchant for jokes.

“Studying great apes is important for understanding which features of human cognition and behavior are shared and likely evolved in a common ancestor millions of years ago,” says Christopher Cropane at Johns Hopkins University in Maryland. “This study provides interesting evidence that all monkeys appear to engage in playful teasing behavior and also opens an avenue for future research in other species.”