The Ape Who Could Play Make-Believe

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WWe know that other great apes can do many of the same things as humans. Since Jane Goodall’s pioneering studies of chimpanzees, ethologists have accumulated decades of observations of wild and captive great apes acting in many ways like humans. We know that other great apes can use tools; make faces; and show empathy. But questions remain about the limits of their cognition.

In a study published yesterday in Sciencebiologists at Johns Hopkins University report that a captive bonobo can “pretend,” which requires imagining things beyond the here and now.

“Imagination has long been considered an essential part of what it means to be human, but the idea that it may not be exclusive to our species is truly transformative,” study author Christopher Krupenye, a psychology and brain science researcher, said in a statement.

We’ve all seen young children pretending to interact with imaginary objects, such as sipping invisible tea from a cup. Around age 2, humans engage in pretend scenarios, but to date there have been no controlled studies of so-called “pretend” in other animals. This is not an easy task. If you think about it, pretend play requires forming a mental representation of something that is absent and distinguishing it from perceptions of reality.

Read more: “Empathy, morality, community, culture: monkeys have it all”

Krupenye and co-author Amalia PM Bastos worked with Kanzi, a 43-year-old captive bonobo (now deceased) famous for his revolutionary language abilities. Kanzi was the first known non-human ape to understand spoken English and communicate using more than 300 symbols. The researchers presented Kanzi with an 18-trial session in which he was rewarded with juice for correctly choosing between two clear bottles, one empty and one with juice.

Then Kanzi was given two clear, empty cups. After the researchers pretended to fill them from an (empty) pitcher and then put the imaginary contents of a cup back into the pitcher, Kanzi had to respond, “Where’s the juice?” Without receiving a reward this time, he chose the cup still containing the imaginary juice in 68% of cases, which is much more than chance.

In a related experiment, Kanzi had to choose which clear jar contained fake grapes after observing a researcher pretending to sample one from each jar and then “emptying” one of the jars. Again, Kanzi chose the jar that still contained far more fake grapes than chance would have it.

Kanzi’s behavior showed that he could imagine absent things, which opens new questions about whether the behavior observed in wild monkeys is also based on imagination. For example, wild female chimpanzees carry sticks, perhaps to imitate the way chimpanzee mothers carry their children.

“The ability to form secondary representations of fake objects is within the cognitive potential of at least one cultured ape and likely dates back 6 to 9 million years to our common evolutionary ancestors,” the study authors concluded.

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Main image: Patrick Rolands / Shutterstock

• Devin Reese

  Published on February 6, 2026

  Devin Reese is the editor-in-chief of Natural history and a science writer based in Alexandria, Virginia.