It’s pretty much always been assumed that chimpanzee sign language in the wild is much less sophisticated than recent research has shown.
See http://news.bbc.co.uk/earth/hi/earth_news/newsid_9475000/9475408.stm for a fascinating tale of how our perceptions of our closest relatives are being changed.
One interesting point from the research is that a number of the signs used by chimpanzees are similar to those used by other great apes and even humans, pointing to the possibility that they are descended from a common gesture language used by our common ancestors.
Read the entire piece for more.
Just for fun, here are some more interesting bits of interest . . . Ape Women: 10 Dedicated Primate Researchers (https://www.mentalfloss.com/blogs/archives/59996) and Bonobo Co-Scream Gestures and Protolanguage (http://jeroenarendsen.nl/2007/05/bonobo-co-scream-gestures-and-protolanguage/).
– Brian