Play-acting orang-utans signal their desires

They might not win any Oscars, but orang-utans can act. They have been caught on camera performing "pantomimes", in which they express their intentions and desires by acting them out. The finding challenges the view that these behaviours are exclusive to humans.

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.