Scientists sat across from a 43-year-old bonobo called Kanzi to have an imaginary tea party. Here’s what happened.
The ability to imagine has long been thought of as uniquely human - but scientists have discovered that apes can also extend their mental lives “beyond the here and now”.
In a series of tea party-like experiments, researchers at Johns Hopkins University in the US demonstrated for the first time that apes can use their imagination and “play pretend”. One bonobo engaged with cups of imaginary juice and bowls of pretend grapes, in a similar way you’d expect a toddler to.
The study, published in the journal Science, says its findings have challenged long-held assumptions about the abilities of animals, suggesting that the capacity to understand pretend objects is within the cognitive potential of an enculturated ape. This ability likely dates back up to nine million years ago.
A ‘game-changing’ discovery into Apes’ minds
“It really is game-changing that their mental lives go beyond the here and now,” says co-author Christopher Krupenye. “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.”
How do scientists know apes can use their imagination?
Up until now, there had been no controlled studies of pretense in nonhuman animals, despite anecdotes of animals seemingly engaging in “pretending behaviour”.
For example, young chimpanzees in the wild have been observed carrying and playing with sticks, holding them in a similar way to how a mother would hold her infant.
Krupenye and co-author Amalia Bastos, who is a lecturer at Scotland’s University of St Andrews, wondered if they could test this capacity to pretend in a controlled environment.
A tea party for apes
The researchers created experiments very similar to a child’s tea party to test a 43-year-old bonobo called Kanzi, who had been reported to have engaged in pretense and could respond to verbal prompts by pointing.
In each test, an experimenter and Kanzi faced each other across a table set with either empty pitchers and cups or bowls and jars. In the first task, there were two empty, transparent cups on the table alongside an empty transparent pitcher.
The experimenter tipped the pitcher to “pour” a little pretend juice into each cup, then mimed dumping the juice out of one cup. They then asked Kanzi: “Where’s the juice?”
The ape pointed to the correct cup that still contained pretend juice most of the time, even when the experimenter changed the location of the cup filled with pretend juice.
In case Kanzi thought there was real juice in the cup, even if he couldn’t see it, the team ran a second experiment. This time there was a cup of real juice alongside the cup of pretend juice. When Kanzi was asked what he wanted, he pointed toward the real juice almost every time.
A third experiment repeated the same kind of concept except with grapes. The experimenter pretended to eat part of a grape from an empty container then placed it inside one of the two jars. They pretended to have emptied one of the containers and asked Kanzi where the grapes were. Kanzi again indicated the location of the pretend object.
“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 says. “Kanzi is able to generate an idea of this pretend object and at the same time know it’s not real.”
While Kanzi wasn’t perfect in his answers, he was consistently correct.
“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 adds. “We should be compelled by these findings to care for these creatures with rich and beautiful minds and ensure they continue to exist.”
The researchers now hope to explore other facets of imagination in apes, such as their ability to think about the future or to think about what’s going on in the minds of others.
