Bonobo Enjoys a Pretend “Tea Party”, Giving a Glimpse of Their Inner Mental Life

If you have seen a 7-year-old chanting “Avara Kedavra” with a stick fashioned into a wand, or making spaghetti from Play-Doh, you will realize that their imagination is the way they study the world, and make the most out of it. As adults, we learn to “fake it till we make it”, developing structured roleplay games like D&D. Now, we can’t call this trait unique to ours, as a male bonobo enjoys a pretend “tea party”.

Kanzi wasn’t just another bonobo. He was the first non-human great ape to understand hundreds of English words and to use symbols called lexigrams to communicate. Now, he has displayed the first-ever instance of a non-human primate to exhibit pretence, in experiments reported in Science. The ape preferred a cup that scientists pretended to fill with juice to an empty one.

Bonobos are among the closest relatives of humans, and the study shows that their ability to imagine is closer to ours than we give them credit for. They might be quite good at conceiving objects, events, or individuals that are not present in front of them. Panbanisha, a captive bonobo, tried to “pluck” blueberries from a picture and then moved her fingers to her mouth, as if trying to eat the imaginary fruit. Young, female wild chimpanzees have also been recorded carrying logs like dolls.

Amalia Bastos, a comparative psychologist at the University of St Andrews, UK, who co-authored the study with cognitive scientist Christopher Krupenye at Johns Hopkins University in Baltimore, Maryland, replicated a ‘tea party’ task used in children to test if apes are capable of make-believe explicitly.

Researchers taught Kanzi to choose a transparent cup filled with juice over an empty one. Next, the scientists moved on to the tea-party task. They showed him two cups, then pretended to fill them with juice from an empty jug. Kanzi was asked to pick a cup after it was inverted— to ‘empty’ the imaginary juice. Out of 50 trials, the bonobo chose the ‘full’ cup 34 times, a figure well above the expected values had his choices been random. In a task similar to this with grapes, Kanzi went for pretend fruit in 69% of trials.

Bastos and Krupenye took measures to rule out explanations other than pretence. A control setup showed that Kanzi didn’t merely assume that both cups contained juice initially. The tea-party experiments were conducted by researchers unaware of the hypothesis being tested. What remains to be determined is whether apes engage in pretend play in the wild, and scientists are already collecting evidence for this behavior.