Via New Scientist:
Non-human great apes such as orang-utans and chimpanzees were already known to display meaningful gestures. They might throw an object when angry, for example. But that is a far cry from displaying actions that are intentionally symbolic and referential – the behaviour known as pantomiming.”Pantomime is considered uniquely human,” says Anne Russon from York University in Toronto, Canada. “It is based on imitation, recreating behaviours you have seen somewhere else, which can be considered complex and beyond the grasp of most non-human species.”
Yet over years she has worked with great apes, Russon has seen several cases that she thought could be considered pantomiming. So to gather more concrete evidence, she and colleague Kristin Andrews searched through 20 years of data on the behaviour of free-ranging, rehabilitated orang-utans.
They found 18 cases of orang-utans clearly acting out a message. Sometimes it was a simple mime, such as body-scratching using a stick, probably to encourage another orang-utan to groom the actor.
In more elaborate cases, orang-utans faked an inability to do something in order to elicit help. One even re-enacted an event that had happened in the past, when a researcher had used a leaf to treat the young ape’s sore foot.
Many of the cases were from Russo’s own research, and some she captured on camera, like the case of the orang-utan Siti (see video above), who faked her inability to open a coconut, feigned an expression of defeat, then mimed to a human the action of cutting it open with a machete.
The research is published in Biology Letters (DOI: 10.1098/rsbl.2010.0564). The abstract reads:
We present an exploratory study of forest-living orangutan pantomiming, i.e. gesturing in which they act out their meaning, focusing on its occurrence, communicative functions, and complexities. Studies show that captive great apes may elaborate messages if communication fails, and isolated reports suggest that great apes occasionally pantomime. We predicted forest-living orangutans would pantomime spontaneously to communicate, especially to elaborate after communication failures. Mining existing databases on free-ranging rehabilitant orangutans’ behaviour identified 18 salient pantomimes. These pantomimes most often functioned as elaborations of failed requests, but also as deceptions and declaratives. Complexities identified include multimodality, re-enactments of past events and several features of language (productivity, compositionality, systematicity). These findings confirm that free-ranging rehabilitant orangutans pantomime and use pantomime to elaborate on their messages. Further, they use pantomime for multiple functions and create complex pantomimes that can express propositionally structured content. Thus, orangutan pantomime serves as a medium for communication, not a particular function. Mining cases of complex great ape communication originally reported in functional terms may then yield more evidence of pantomime.