Bonobos, it turns out, can play pretend too. Just like human children, these great apes engage in imaginative play, as evidenced by a study involving a bonobo named Kanzi. The research, conducted by Amalia Bastos and Christopher Krupenye at Johns Hopkins University, reveals that Kanzi successfully participated in three pretend tea party-style experiments, showcasing a level of imagination that was previously thought to be exclusive to humans.
The study builds upon earlier observations of individual apes playing alone, suggesting that simulated play might be a broader skill among great apes. Female chimpanzees in the wild, for instance, were seen carrying and playing with sticks as if they were dolls, mirroring how mother chimpanzees carry infants. However, the anecdotal nature of these observations left room for doubt, prompting the researchers to conduct more controlled experiments.
In 2024, Bastos and Krupenye designed a series of experiments using juice and grapes to test Kanzi's ability to distinguish between real and imaginary objects. Kanzi was asked to choose between a bottle with juice and an empty one, and he correctly identified the juice-filled bottle in 18 trials. The researchers then presented Kanzi with empty, transparent cups and pretended to pour juice into them, pouring it out and back into the pitcher. When asked where the juice was, Kanzi chose the cup with the imaginary juice 68% of the time, demonstrating a higher level of accuracy than random selection.
To further test Kanzi's understanding of the difference between real and imaginary, the researchers presented him with a cup containing juice and an empty cup filled with imaginary juice, asking him to choose. Kanzi correctly selected the cup with juice 14 out of 18 times. The final experiment involved a similar setup with a grape, and Kanzi identified the jar with the imaginary grape 68.9% of the time, faster than in the previous experiment.
The researchers concluded that the capacity for representing pretend objects is not uniquely human. Primate behavioral ecologist Nicholas E. Newton-Fisher, who was not involved in the study, praised Kanzi's skills, suggesting that his abilities require a reevaluation of our understanding of ape cognition. Newton-Fisher also noted that while adult apes' mental abilities are often compared to human children, apes have their own unique cognitive capabilities, and how imagination manifests in them may differ from humans.
Despite the promising findings, the researchers caution that generalizing the results to other bonobos and ape species will require further investigation. However, Bastos expresses confidence that similar skills might be found in other apes, given the abundance of anecdotal evidence.
