A 44-year-old bonobo named Kanzi demonstrated an understanding of human concepts of pretense, challenging long-held beliefs about the cognitive abilities of non-human primates. The findings, published February 5 in Science, stem from experiments designed to determine if Kanzi could grasp the idea of objects or actions that aren’t real.
Researchers, including Amalia Bastos of the University of St Andrews in Scotland and Christopher Krupenye of Johns Hopkins University, presented Kanzi with a scenario resembling a child’s tea party. They pretended to pour juice from an empty pitcher into two glasses, then “poured” the nonexistent liquid back into the pitcher from one of the glasses. When asked which glass still contained the “juice,” Kanzi was able to consistently identify the correct glass, suggesting he understood the concept of an imaginary substance.
Kanzi’s ability to communicate using lexigrams – symbols representing words – was central to the study. He first came to the attention of researchers in 2023 when, upon meeting Bastos, he used his lexigram board to request that she and a colleague “chase” and “tickle” each other, and appeared to enjoy their playful pretense. This observation sparked the series of experiments that ultimately tested his understanding of pretend scenarios, according to Bastos.
The experiments were designed to assess whether Kanzi could create a “secondary representation,” a cognitive ability previously thought to be unique to humans. “Classic childhood activities like tea parties and sword fights with sticks demonstrate the human ability to… understand that objects can represent other objects,” explained a summary of the research published by Johns Hopkins University.
Krupenye, an assistant professor of psychological and brain sciences at Johns Hopkins, noted the significance of the findings, suggesting Kanzi possessed the capacity to imagine. The research builds on previous work highlighting Kanzi’s remarkable cognitive abilities and his capacity for language acquisition. The study was conducted at the Ape Cognition and Conservation Initiative in Iowa, where Kanzi resided.
Kanzi passed away in March 2025, shortly before the publication of the study. The research team continues to analyze data collected during the experiments, and further studies are planned to investigate the extent of pretend play and imaginative capacity in other bonobos and great apes.
