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http://www.scienceblog.com/cms/chimps_point_to_spot_they_d_like_groomed_10254.html

Chimps point to spot they'd like groomed

Created 03/22/2006 - 06:08

It was once thought that only humans gestured to direct another
person's attention, but such "referential" gesturing was recently
observed in wild chimpanzees.

John Mitani, University of Michigan anthropology professor, and
colleague Simone Pika, a postdoctoral fellow in psychology at
University of St. Andrews in Scotland, observed male chimps habitually
using "directed scratches" to request grooming of specific areas on
the body. The findings suggest that our closest living relatives may
be capable of mental-state attribution, making inferences about the
knowledge of others.

Up until now, scientists saw directed scratching only in captive
chimps and language-trained apes who interacted with humans, Mitani
said.

"The more we learn, the more we see chimpanzees employing remarkable,
seemingly human-like behaviors," Mitani said. "To me that is one of
the lessons of this little paper." The findings appear in today's
issue of Current Biology, in a paper entitled "Referential Gestural
Communication in Wild Chimpanzees."

To reach their conclusions, Pika and Mitani studied the social
grooming habits of male chimps in the Ngogo community in Uganda's
Kibale National Park. During observation, male chimps routinely
scratched a certain spot on themselves in view of their grooming
partner, usually in a loud, exaggerated manner. In the majority of
cases (64 percent) the groomer responded immediately by stopping and
moving to groom the exact spot the gesturer had just scratched, Mitani
said.

The behavior appeared frequently between males who formed strong
social bonds, and Mitani surmised that further study might reveal that
males who do not display such friendly relations do not engage in the
behavior as often.

"It's almost as if it's being used selectively by males who know that
they are going to obtain a positive response," similar to asking a
friend for a favor as opposed to a stranger, Mitani said.

Pika and Mitani observed male chimps because they groom each other
more frequently than females do.

Historically, researchers thought animal gestures provide information
only about the communicator's emotional state. Referential
communication, such as pointing to something in the external
environment with the expectation of a specific response from another,
was considered beyond the capability of non-human primates in the
wild.

However, scientists have known for some time that animals use calls to
refer to objects and events in the external world in a seemingly
referential fashion, Mitani said. For example, an animal might utter
distinct warning sounds to denote different kinds of predators.
However, documenting the use of referential gestures in animals has
lagged behind, Mitani said.