Researchers recently discovered that chimps have over twice the number of sign language-like gestures than previously thought. Through painstaking effort, the researchers learned to decode which gestures meant, "I like your face," versus "I'm going to claw your face off."
The first step to compiling a comprehensive database of ape language is full immersion - the same way you would study any other language. Past researchers, it seems, would miss out on a lot of important gestures. They'd have to stay behind during chimp raiding parties, when groups of males went off to patrol the border of their territory or encroach on the group nearby. They'd also get kicked out of chimpanzee alone time, when males and females courted. There have to be some important gestures going on then.
Catherine Hobaiter, the lead researcher, spent two years with a single group of chimpanzees. They say familiarity breeds contempt, and Hobaiter spent enough time with them to get them thoroughly contemptuous of her and not caring a bit what she thought of any of them. Once they were used to her, they went about their daily life without caring what she did. What she did was film 120 hours of examples of their repeated gestures. Some were easy to guess at, since they bore a striking resemblance to human gestures. The chimps would wave their hands around to get their young to become playful or beckon other chimps over.
Finally, it came time to analyze what each gesture meant. This caused confusion in the past, because not all gestures result in the desired action. (In humans, an innocent middle finger, intended only to convey that the recipient is a massive jerk when it comes to using turn signals, can result in rolled eyes or a severe beating - the latter of which is surely not the gesturer's intended outcome.) So researchers paid attention to the gesture itself, whether or not the gesture was repeated more urgently as time when on and the desired response did not come, and the final attitude of the gesturer. If the chimps displayed contentment after the last gesture, it indicated that the other chimp had responded the way the first chimpanzee had hoped. If the first chimp seemed frustrated, what they had was a failure to communicate. The team identified sixty-six gestures in all. Hopefully, they will be compiled and given out to people who fear getting ripped apart by chimpanzees for making a faux pas.
Read more via the BBC