Historically, researchers thought animal gestures provide information only about the communicator's emotional state. Referential communication, such as pointing to something in the external environment with the expectation of a specific response from another, was considered beyond the capability of non-human primates in the wild.
However, scientists have known for some time that animals use calls to refer to objects and events in the external world in a seemingly referential fashion, Mitani said. For example, an animal might utter distinct warning sounds to denote different kinds of predators. However, documenting the use of referential gestures in animals has lagged behind, Mitani said.