To get treats, apes eagerly pointed them out to humans who didn’t know where they were, a seemingly simple experiment that demonstrated for the first time that apes will communicate unknown information in the name of teamwork. The study also provides the clearest evidence to date that apes can intuit another’s ignorance, an ability thought to be uniquely human.

Because this so-called theory of mind supports many of the capacities that make humans unique, like teaching and language, many believe it is absent from animals. But this work demonstrates the rich mental foundations that humans and other apes share—and suggests that these abilities evolved millions of years ago in our common ancestors.