Which professional communicators always suspected. The guy who worked with Nim Chimpsky, Herbert Terrace, speaks honestly* about his research here.
The language didn’t materialize. A human baby starts out mostly imitating, then begins to string words together. Nim didn’t learn. His three-sign combinations — such as ‘eat me eat’ or ‘play me Nim’ — were redundant. He imitated signs to get rewards. I published the negative results in 1979 in the journal Science, which had a chilling effect on the field.
No surprise there. The baby is imitating a system he is in the process of internalizing. The chimp is aping signs for a reward (often not food, just acceptance). It’s the difference between teaching an assistant and programming a robot.
A friend notes,
A comment has been posted that seeks to keep the door open on Chimp language capabilities: “the Nim Project seems to have been more informed by the linguistic theories of Noam Chomsky rather than the verbal behavior approach of B. F. Skinner”.
Well, and so? They’re not going to talk, no matter which system you use.
* In a field that could use more honesty than it gets.