A study of chimps in the wild has shown that the animals communicate with each other using reproducible gestures that scientists have now been able to document and translate.
Catherine Hobaiter and Richard Byrne, from St Andrews University in Scotland, used video footage to capture thousands of examples of Ugandan free-living chimps gesturing to each other. What the duo were looking for was evidence accompanying each gesture that the animal sending the signal achieved a satisfactory outcome from the recipient.
The animals they studied displayed more than 66 different types of gesture signalling 19 different meanings. The signals included instructions to "stop", "move away", "follow me", "climb onto me" and "climb onto you". These were indicated by various actions such as swinging an arm, turning a somersault, stroking the mouth or presenting the feet.
One particularly provocative gesture adopted by female chimpanzees, which involved loudly crunching on a leaf, was used as a sexual come-on.
According to Hobaiter and Byrne in their paper in Current Biology, "chimpanzees use their gestures in purposeful communication with other chimpanzees... we analysed the meanings of 36 gestures and found them to be used intentionally to achieve 15 purposes, other than in play. There was considerable similarity across individuals, indicating that the meanings are inherent to the gestures, rather than idiosyncratic to particular individuals."