An ingenuous experiment announced last week shows that orangutans communicate with intention. When the orangutans were shown food (delicious items, like bananas and bread, and less appealing food, like celery) that could only be reached with human help, they clearly communicated their desire to be passed the food by using various gestures (blowing raspberries, spitting, pointing). When the researchers pretended to misunderstand the requests by offering only half of the food, offering the wrong food, or pretending to not get the request at all, the apes tried various familiar strategies to be understood. If completely misinterpreted they would devise a new gesture, if half-understood, they would reiterate their gesture with vigor. Current Biology. Mike Tomasello and colleagues have shown similar results with chimpanzees. Live Science, BBC, SciAm.
Meaningful, communicative gestures are shared by humans and other great apes. As with human groups, different groups of chimpanzees and bonobos may use the same gesture to mean completely different things. New Scientist, The Economist, PNAS.