It was the sight of a diminutive Diana monkey attacking a giant crowned eagle in the treetops of the Tai forest in Ivory Coast, west Africa, that gave Klaus Zuberbühler his great insight into the language of monkeys. […] It means that humans, used to regarding ourselves as unique in our ability to think and feel, are not so special. Increasingly scientists believe we are merely at the top of a spectrum of intelligence across the animal kingdom, rather than standing apart from it. We may be better at thinking and more able to articulate our feelings — but animals can do all the same things.
Smarter than you think in The Times.