Scientists study how monkeys talk to each other. They try to teach monkeys to talk to people. Lucy, a chimpanzee, actually learned sign language to communicate with people. After studying Diana monkeys for 20 years, Dr. Z understands how the monkeys talk to each other in the forest.
But when it comes to defining “monkey language,” scientists have not found a truly developed language among any monkeys or apes.
Source: Wade, Nicholas. (2010, January 12). Deciphering the Chatter of Monkeys and Chimps. NYTimes Science