French author François Rabelais believed that laughter is a human trait. But ethologists are wondering whether animals can, like humans, have a sense of humour.
Now, a research team claims that great apes engage in forms of playful teasing that show similarities with joking behaviour in humans.
The experts from the University of California Los Angeles, the Max Planck Institute of Animal Behavior, Indiana University, and the University of California San Diego came to this conclusion after studying the behaviour of several orangutans, chimpanzees, bonobos and gorillas.
They found that these great apes are adept at playful teasing, and sometimes make one of their fellow apes a target and try to provoke a reaction by, for example, waving an object or a body part in their field of vision, or by hitting or poking them.
These mock blows are executed without anger, although they can become more or less persistent.
The academics highlight several similarities between joking behaviour in humans and ape teasing behaviours. “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 a teasing action, repetition, and elements of surprise,” study co-author Isabelle Laumer explained.
But, although the apes’ playful teasing takes many forms, the researchers note that it differs from play in several ways.
“Playful teasing in great apes is one-sided, very much coming from the teaser often throughout the entire interaction, and rarely reciprocated,” lead author Erica Cartmill pointed out. That’s why apes don’t use any particular facial expressions to signal play when they’re teasing their fellow apes.
Another intriguing finding is that these animals only seem to tease when they’re relaxed, as Cartmill and colleagues note in their report published in the journal Proceedings of the Royal Society B.
“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 teasing and its cognitive prerequisites may have been present in our last common ancestor, at least 13 million years ago,” Laumer noted.
The researchers hope their work will inspire scientists to study the evolution of this behaviour in other animal species.