Bonobos have demonstrated the capacity for “pretend play,” a cognitive ability previously thought to be unique to humans, according to a study published today in Science. Researchers at Johns Hopkins University and the University of St Andrews observed Kanzi, a male bonobo, engaging in a simulated tea party, correctly identifying which cup purportedly contained liquid even after a researcher pretended to pour it into a different cup and then empty it.
The experiment involved presenting Kanzi with two cups, one seemingly filled with juice and the other empty, after a staged pouring and emptying sequence. Despite the absence of actual liquid, Kanzi consistently selected the cup he believed to contain the juice, indicating an understanding of the pretense. While not flawless, researchers Christophe Krupenye and Amalia Bastos deemed the results sufficient to demonstrate imaginative capacity in the bonobo.
“We see really striking and exciting that the research suggests apes can reach up with things that aren’t there,” Bastos stated in a press release. “Kanzi can therefore generate an idea of the object (in this case the juice that is supposedly poured) and at the same time know that it is not real.”
Kanzi, who died in March 2025 at the age of 44 at the Ape Initiative in Des Moines, Iowa, was already renowned for his cognitive abilities, being the first non-human ape to comprehend spoken English and communicate using lexigrams – symbolic representations of language. His participation in this latest study built upon decades of research into animal cognition.
The findings challenge long-held assumptions about the uniqueness of human imagination. Researchers have previously observed behaviors resembling pretense in chimpanzees and other great apes, such as a bonobo named Panbanisha mimicking the act of eating imaginary blueberries and chimpanzees carrying logs as if they were infants. But, this study marks the first explicit demonstration of pretend play in a non-human animal.
The study’s implications extend beyond simply redefining animal intelligence. According to the Dutch broadcaster VRT, the research suggests animals may possess a richer inner mental life than previously acknowledged. The findings also align with observations that bonobos, like humans, experience complex emotions such as nightmares and homesickness.
Researchers are now exploring whether other animal species exhibit similar imaginative capabilities. The study does not address whether Kanzi, or other apes, experience the same subjective quality of imagination as humans, but it does provide compelling evidence that the capacity for pretense is not exclusive to our species.
