Humans may not be the only primates with the power to imagine. A bonobo named Kanzi recently showed that he could keep track of make-believe juice and grapes during a pretend tea party.

This finding adds to a growing body of evidence that apes — primates without a tail, such as bonobos and gorillas — can picture things that aren’t really there. Scientists once thought only people did this.

By a year old, human children can start playing pretend. By age three, most kids can build whole imaginary words in their minds. This ability is necessary for many complex tasks.