Scratch me ...

Researchers have found evidence for referential gestures in wild chimps. Humans commonly use referential gestures that direct the attention of recipients to particular aspects of the environment. Because the recipient of a referential gesture must infer the signaler's meaning, the use of these gestures has been linked with cognitive capacities such as the ability to recognize another individual's mental state.

As the press release states:

The gesture studied by the researchers--a "directed scratch"--involved one chimpanzee making a relatively loud and exaggerated scratching movement on a part of his body that could be seen by his grooming partner. In the majority of cases, the indicated spot was groomed immediately afterward by the recipient of the gesture. The scratch gesture occurred between pairs of adult males and was used more often in pairs consisting of high-ranking males. On the basis of their observations, the researchers suggest that the "directed scratch" gesture may be used communicatively to indicate a precise spot on the body and to depict a desired future action, namely grooming. The findings also suggest that the recipient of the signal has an understanding of the intended meaning of the gesture. "Directed scratches" therefore qualify as referential and iconic, in the technical sense, and might provide support for the hypothesis that some form of mental-state attribution may be present in our closest living relatives.

Full reference is Pika et al.: "Referential-Gestural Communication in Wild Chimpanzees (Pan troglodytes)." Current Biology 16, R191-R192, March 21, 2006.