The textbook I am using in my grammar class, The Linguistic Structure of Modern English, suggests that humans are unique in that they are the only species known to show abstract language use in the wild (they do mention the example of chimpanzees that have been trained to use sign language).
Very recent research, however, provides a potential counter example: Dolphin names. It has long been known that dolphins communicate with each other verbally. And since the 1960s, researchers have believed that individual dolphins use a “signature whistle” to identify themselves that is recognised by others in their population. What is new, however, is the evidence that dolphins use the signature whistles of other dolphins to refer to them—that is to say, recognise a particular whistle sequence as being symbolic of a particular individual dolphin, distinct from themselves.
This use of arbitrary signals to refer to a specific object, if true, would invalidate the claims in Brinton Read the rest of this entry »