Researchers at Johns Hopkins University report that Kanzi, a language-trained bonobo, followed pretend “tea party” scenarios by pointing to where an experimenter had acted as if imaginary juice and grapes were located. The work, published in Science, adds experimental evidence to a long-running debate over whether elements of pretense and imagination are unique to humans.
Researchers studying animal cognition have reported experimental evidence that a bonobo could keep track of pretend objects during structured “tea party” interactions—an ability often treated as a hallmark of human childhood development.
The team, led by Johns Hopkins University scientist Christopher Krupenye and co-author Amalia P. M. Bastos, tested Kanzi, a bonobo housed at the Ape Initiative in Des Moines, Iowa, who had been trained to understand spoken words and communicate using lexigrams.
A tea-party-style test of “pretend juice”
In one experiment adapted from developmental psychology tasks used with children, an experimenter staged an imaginary juice-pouring scene using empty, transparent cups and an empty, transparent pitcher. After acting as if juice had been poured into both cups, the experimenter pantomimed emptying the “juice” from one cup and then asked Kanzi, “Where’s the juice?”
Kanzi pointed to the cup treated as still containing the pretend juice 34 out of 50 trials (68%), a rate above chance.
Real-versus-pretend check
To address an alternative explanation—that Kanzi might have believed real juice was hidden in the empty cups—the researchers ran a related test in which one option contained actual juice and the other was associated with pretend juice. When asked what he wanted, Kanzi chose the cup with real juice 14 out of 18 times (about 78%), indicating he could differentiate the staged pretense from a real reward.
An imaginary grape task
In a third experiment, the experimenter acted as if taking a grape from an empty container and placing it into one of two transparent jars, then pantomimed emptying one jar before asking, “Where is the grape?” Kanzi selected the jar associated with the pretend grape 31 out of 45 times (about 69%).
What the authors—and outside scientists—say it means
“It really is game-changing that their mental lives go beyond the here and now,” Krupenye said in Johns Hopkins’ release about the study.
Bastos, now a lecturer at the University of St Andrews, said Kanzi could represent a pretend object while also understanding it was not real: “Kanzi is able to generate an idea of this pretend object and at the same time know it’s not real.”
The paper argues that this capacity to form “secondary representations” of pretend objects is within the abilities of at least one enculturated ape and could have evolutionary roots dating back roughly 6 to 9 million years, to a common ancestor shared by humans and other apes.
Some researchers urged caution in interpreting the findings. In an Associated Press report, Duke University psychologist Michael Tomasello said he would want to see the ape initiate pretend actions (such as pretending to pour liquid) to be convinced the behavior matches human-style pretense.
Kanzi’s case may also be difficult to generalize because of his unusual rearing and training history. Several outlets reported that Kanzi died in 2025 at age 44, meaning the experiments reflect data from a single, well-studied individual.
The researchers say the results provide a framework for testing pretend representation more broadly in other apes and, potentially, other animals.
