A bonobo named Kanzi was sitting at a table across from a researcher. On the table are two completely empty clear cups and an empty clear jug. The researcher pretends to pour juice into both cups. Then she pretends to dump the juice out of one of them, turning it upside down and shaking it as if to show it’s empty. 

Then she asks Kanzi, “Where’s the juice?” 

There is no juice, but most of the time, Kanzi points to the cup that is supposed to still contain the imaginary juice. 

The study, published in Science, is the first controlled evidence that a nonhuman ape can represent something mentally that isn’t physically there, and keep track of it as events unfold. 

In the study, three controlled experiments were used to test whether an ape could actually track a pretend object in a consistent, rule-based way. 

In the first experiment, Kanzi watched the pretend pouring and pretend dumping, and then had to identify which cup still 'had' the invisible juice. Even when the researchers moved the cups around, he usually pointed to the correct one. That suggests he wasn’t just memorising a position, he was mentally tracking the imagined contents. 

But maybe, you might think, he believed there was real juice hidden in there somehow. So the researchers ran a second experiment to rule that out. This time, one cup had real juice in it and the other had pretend juice. When asked what he wanted to drink, Kanzi overwhelmingly chose the real juice, so he clearly understood the difference between imagination and reality. 

In a third test, they switched from juice to grapes. The researcher pretended to take a grape from an empty container and place it into one of two jars, then pretended to empty one jar. When asked, 'Where’s the grape?' Kanzi again pointed to the jar that was supposed to still contain the imaginary grape. 

This matters because imagination has long been considered one of the defining features of being human. Human children typically start pretend play around age two, and even younger babies show signs they understand make-believe scenarios. But until now, scientists hadn’t demonstrated this ability under controlled conditions in other animals. 

Humans and bonobos share a common ancestor from around six to nine million years ago. If the roots of imagination stretch back that far, then this capacity didn’t suddenly appear with us. It may be part of a much older cognitive toolkit. 

If apes can think about things that aren’t present, if they can hold an imagined object in mind and update that representation as events change, then their experience of the world may be far richer than we’ve assumed. 

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