Apes Show Imagination & Pretend Play – Challenging What Makes Us Human

For decades, the capacity for imagination has been considered a defining characteristic of human intelligence. But new research suggests this ability may not be uniquely ours. A study published today in Science demonstrates that a bonobo named Kanzi can engage in pretend play, a cognitive feat previously thought to be exclusive to humans.

Researchers at Johns Hopkins University and the University of St Andrews designed a series of experiments, described as “tea party-like,” to test Kanzi’s ability to understand and participate in scenarios involving imaginary objects. Consistently, Kanzi demonstrated an understanding of pretend objects, such as imaginary juice and grapes, challenging long-held assumptions about animal cognition.

“It really is game-changing that their mental lives go beyond the here and now,”

The experiments involved Kanzi sitting across from a researcher at a table set with cups and pitchers, or bowls and jars. In one test, the researcher pretended to pour juice into cups from an empty pitcher, then pretended to empty one of the cups. When asked where the juice was, Kanzi consistently pointed to the cup that still “contained” the imaginary liquid. A follow-up experiment confirmed Kanzi wasn’t simply selecting based on the presence of real juice, as he overwhelmingly chose the cup with actual juice when offered both real and pretend options.

Similar experiments were conducted with grapes, yielding comparable results. Kanzi accurately identified the location of pretend grapes even after the researcher pretended to place them in one of two jars.

While Kanzi wasn’t perfect in his responses, his consistent accuracy across multiple trials was striking. “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,” says Amalia Bastos, a lecturer at Scotland’s University of St. Andrews and co-author of the study.

This finding builds upon earlier observations of seemingly imaginative behavior in apes. Anecdotal reports have described chimpanzees in the wild carrying sticks as if they were infants, and a captive chimpanzee appearing to drag imaginary blocks across the floor after playing with real ones. However, this is the first controlled study to demonstrate this capacity in a non-human animal.

The implications of this research are significant. Christopher Krupenye, an assistant professor in the psychological and brain sciences department at Johns Hopkins University, notes that the ability to imagine is fundamental to many higher-level cognitive functions in humans. “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,” he explains.

This discovery echoes a similar shift in understanding that occurred when Jane Goodall first observed chimpanzees using tools. “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,” Krupenye adds.

Researchers estimate that the capacity for pretend play may date back 6 to 9 million years, to our common evolutionary ancestors. This suggests that the roots of imagination are deeply embedded in the primate lineage.

The study’s findings open new avenues for research. The team plans to investigate whether other apes and animals exhibit similar abilities and to explore other facets of imagination in apes, such as their capacity for future planning and understanding the perspectives of others.

“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 says. He emphasizes the ethical implications of this research, arguing that recognizing the complex mental lives of apes should compel us to prioritize their conservation and welfare. “We should be compelled by these findings to care for these creatures with rich and beautiful minds and ensure they continue to exist.”

The research was supported by funding from the Johns Hopkins Provost’s Postdoctoral Fellowship Program, Templeton World Charity Foundation, CIFAR Azrieli Global Scholars, and an Early Career Collaboration Enhancement Award from the Diverse Intelligences Summer Institute.