What is language? The definition has always been a matter of some controversy. Duane Rumbaugh describes language as "an infinitely open system of communication;" others believe that language is a peculiarly human achievement and involves intricate usage of symbols, grammar, and representations of real world situations. Scientists have been experimenting for centuries to find out if great apes - humans' closest relatives - can use language. Even though no one really knows how intelligent apes are, scientists are able to discover and categorize several ways of communication that ape uses instinctively or is able to use once taught by human. Not blessed with the talent of speech as human are, wild apes generally use verbal signals and visual signals, particularly body language and facial expression to express themselves; various experiments over the years have showed that apes can learn sign languages, understand simple words and use other language...