Theory of Mind in Apes

http://www.smithsonianmag.com/science-nature/monkey-200801.html?c=y&page=1

From The Smithsonian:

Santos' interest here is in what psychologists call "theory of mind," the ability to impute thoughts and intentions to another individual, one of the cornerstones of human cognition. "Sitting here talking with you," Santos explains, "all I can see is your behavior, but I draw inferences about your desires and thoughts. The interesting question is, how far back in evolutionary time does that ability extend? Can it exist without language?" As recently as a decade ago, the conventional wisdom doubted that even chimpanzees, which are more closely related to human beings than are monkeys, possessed theory of mind. This view is changing, in large measure because of the work of Santos and her collaborators. With her students in tow and a small bag of grapes in her pocket, Santos is now out to demonstrate the phenomenon—if a Macaca mulatta can be induced to cooperate.