Forget what you saw in Rise of the Planet of the Apes. Apes can’t make sentences, even if someone has tried really hard to teach them sign language. The documentary Project Nim describes one attempt to teach sign language to a chimpanzee:
The chimpanzee used in this experiment was named Nim Chimpsky, which was a mocking reference to the linguist Noam Chomsky, who had predicted that no such experiment would work. Chomsky said that it’s about as likely that an ape will prove to have a language ability as there is an island somewhere with a species of flightless birds waiting for humans to teach them to fly. In other words, if apes could use language, they’d be doing so already.
Two things about the story of Nim Chimpsky shocked me: the lack of concern for ethics and the lack of scientific methodology. The whole rationale for the study was based on the idea that chimpanzees are like us, and yet the researchers stole a baby chimpanzee from its mother. If chimpanzees are like us, that would be a horribly cruel thing to do. When the project was finished, Nim was sold to be used in other kinds of medical research. He lived for years in a laboratory cage, undergoing painful experiments, before he was rescued and sent to live the rest of his life at the primate sanctuary at the Cleveland Amory Ranch.
Although the study was supposedly being done for scientific purposes, the whole project seemed to be done carelessly. For one thing, the people who were supposedly training Nim to use American Sign Language and evaluating his success at using signs could not actually speak American Sign Language. Thus, they weren’t qualified to say whether Nim’s gestures were real language, as opposed to nonsense. In fact, the study was done so carelessly that the researchers thought that they were getting Nim to use language, when they really weren’t.
When Herbert Terrace, the head of Project Nim, carefully reviewed the videotapes, he found that Nim wasn’t having conversations, he was merely mimicking the people around him: “Previously, I had been so fixated on watching Nim’s hands that I missed what his teachers had been doing on the side while in shadow. About one quarter of a second prior to Nim’s signing, they were making the same or similar signs!” In other words, Nim was aping his handlers. Monkey see, monkey do.
Terrace explained the failure of the experiment in a landmark article in Science. In later years, Terrace explained, “Instead of learning to converse with their trainers, Washoe and Koko, like Nim, only learned to use imperatives that were involuntary demands for primary rewards.” Terrace made a similar criticism of the work with the famous African gray parrot Alex.
The lack of scientific rigor in the Project Nim is part of a recurring pattern. As Chomsky explained in an e‑mail interview, “For whatever reason, the study of human higher mental faculties is pervaded by a curious form of irrationality, foreign to the sciences.”
No matter how hard you try to teach apes to use signs, the apes never show any evidence of having an experience like the one that Helen Keller had at the water pump when she was seven years old. Apes never start demanding to know what things are called. They never start putting the signs together into intelligible sentences with subjects and predicates. You see the same thing in language research with parrots. Although parrots may parrot what you say, and they can be trained to give specific responses to highly sophisticated prompts, they never go on to have real conversations like Dr. Dolittle’s Polynesia the parrot.