Kanzi the bonobo could play pretend — a trait thought unique to humans

A bonobo named Kanzi could play pretend, challenging ideas about animal imaginations

To primatologists around the world, Kanzi was a star. After years of training with sign language and a specialized keyboard, the 44-year-old bonobo had gained an unusually sophisticated understanding of human words, making him the focus of decades of research into nonhuman primates’ language abilities. But Christopher Krupenye, a cognitive scientist at Johns Hopkins University, wanted to test something different: Kanzi’s imagination. In March 2025, Krupenye and his colleagues acted out a version