According to a new study in Current Biology, chimpanzees can communicate 19 specific messages using 66 different gestures. Dr. Catherine Hobaiter, who led the research, says this is the only example of an intentional communication system (in which one individual sends a message to another individual) amongst animals. Among the chimpanzee messages: exposing the sole of a foot means “climb on my back,” while nibbling strips off a leaf is a sexual invitation.

image via Current Biology

via BBC