This Bonobo Just Did Something Scientists Thought Only Humans Could Do

A bonobo demonstrated the ability to track imaginary objects in controlled tests, challenging the belief that imagination is uniquely human and hinting at deep evolutionary roots.

In a set of carefully designed experiments modeled on children’s tea parties, researchers at Johns Hopkins University found that an ape could engage in pretend play. The results mark the first controlled demonstration that an ape can imagine objects that are not actually there, a skill long considered uniquely human.

Across three separate tests, the bonobo interacted with invisible juice and imaginary grapes in a consistent and reliable way. The performance challenges longstanding assumptions about the limits of animal cognition.

The researchers conclude that the ability to understand pretend objects falls within the mental capacities of at least one enculturated ape. They suggest this ability could trace back 6 to 9 million years to a common ancestor shared by humans and other apes.

Ape Imagination Upends Human Uniqueness in Science Study

“It really is game-changing that their mental lives go beyond the here and now,” said co-author Christopher Krupenye, a Johns Hopkins assistant professor in the Department of Psychological and Brain Sciences who studies how animals think. “Imagination has long been seen as a critical element of what it is to be human, but the idea that it may not be exclusive to our species is really transformative.

“Jane Goodall discovered that chimps make tools, and that led to a change in the definition of what it means to be human, and this, too, really invites us to reconsider what makes us special and what mental life is out there among other creatures.”

The study was published on February 5 in Science.

In a series of tea party-like experiments, Johns Hopkins University researchers demonstrate for the first time that apes can use their imagination and play pretend, an ability thought to be uniquely human. Credit: Johns Hopkins University

Pretend Play in Human Children and Animal Anecdotes

Human children begin engaging in make-believe activities such as tea parties by around age two. Even infants as young as 15 months show signs of surprise when someone pretends to pour out a cup and then acts as if it still contains a drink.

Until now, no controlled experiments had tested whether nonhuman animals could truly understand pretense, despite scattered reports from both wild and captive settings.

In the wild, for instance, young female chimpanzees have been seen carrying sticks in ways that resemble how mothers hold infants. In captivity, one chimpanzee appeared to drag invisible blocks across the floor after previously playing with real wooden ones.

Testing Bonobo Kanzi With Tea Party Experiments

Krupenye and co-author Amalia Bastos, a former Johns Hopkins postdoctoral fellow now lecturing at Scotland’s University of St. Andrews, set out to examine this question under controlled conditions.

They designed a series of tea party-style tasks for Kanzi, a 43-year-old bonobo living at Ape Initiative. Kanzi had previously been described as engaging in pretend behavior and can respond to spoken questions by pointing.

During each session, Kanzi sat across from an experimenter at a table arranged with either empty pitchers and cups or bowls and jars.

Kanzi Identifies Pretend Juice in Controlled Cognition Test

In the first experiment, two clear cups and an empty transparent pitcher were placed on the table. The experimenter acted as if they were pouring imaginary juice into both cups, then pretended to empty one of them. After this demonstration, Kanzi was asked, “Where’s the juice?”

Most of the time, Kanzi pointed to the cup that was supposed to still contain the pretend juice. He continued to choose correctly even when the position of the cups was changed.

To rule out the possibility that Kanzi believed there might be real liquid inside the cup, the researchers conducted a second test. This time, one cup contained actual juice, while the other held only imaginary juice. When asked which he wanted, Kanzi almost always selected the cup with real juice.

Bonobo Demonstrates Pretend Play, Revealing Evolutionary Roots of Imagination

In a third task, the researchers repeated the setup using grapes instead of juice. The experimenter pretended to take a grape from an empty container and place it into one of two jars, then acted as if they had emptied one jar. When asked, “Where’s the grape?” Kanzi again indicated the correct location of the pretend grape. Although he did not answer correctly every single time, his responses were consistently above chance.

“It’s extremely striking and very exciting that the data seem to suggest that apes, in their minds, can conceive of things that are not there,” Bastos said. “Kanzi is able to generate an idea of this pretend object and at the same time know it’s not real.”

The researchers say the work opens the door to further investigations into whether other apes or species can engage in pretend play or mentally track imaginary items. They are also interested in studying additional aspects of imagination, including whether apes can think about future events or consider what others might be thinking.

“Imagination is one of those things that in humans gives us a rich mental life. And if some roots of imagination are shared with apes, that should make people question their assumption that other animals are just living robotic lifestyles constrained to the present,” Krupenye said. “We should be compelled by these findings to care for these creatures with rich and beautiful minds and ensure they continue to exist.”

Reference: “Evidence for representation of pretend objects by Kanzi, a language-trained bonobo” by Amalia P. M. Bastos and Christopher Krupenye, 5 February 2026, Science.
DOI: 10.1126/science.adz0743

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