The monkeys who can speak in sentences: ""To our knowledge, this is the first good evidence of a syntax-like natural communication system in a non-human species.""

If you like this sorta thing, go read Next of Kin - David recommended it to me when I did the Great Gorilla Run a few years back and it's a fascinating read. As is The Ape and the Sushi Master - an exploration of ape culture.

Or if you'd like a practical demonstration, hie thee to Monkey World... retaining some self-control if you please...