Nim Chimpsky was a chimp raised in the 1970s in a way close to humans, in the hope he would develop language.

The results were ambiguous on the language front. But something else happened.

The former graduate students in New York believe that Nim had no idea he was a chimpanzee. One of them suggested to me that Nim might have thought he was going to grow up, lose all his facial and body hair and eventually look like the people who were around him. That would be a reasonable supposition. Throughout his life, Nim preferred to be with humans.

Toward the end of his life, he was paired with an ex-circus chimp named Sally Jones. That, I think, was the first deep relationship he had with his own species. They were inseparable. Sally was a lot older, a lot milder. Nim had a reputation for breaking out of his cage in Texas. When Sally came, he would break out of his cage, but then he’d remember her, and he’d go back and get her. He’d lead her out of the cage and they’d go on a little romp together. Cleveland Amory was always afraid that Nim was going to run off into the woods. But he had no desire to run away. Nim would go to the nearest house and bring Sally with him, and they would raid the refrigerator, go through the closets and try on any shoes that were lying around, and sometimes they’d get into bed and turn on the TV.

http://www.salon.com/books/int/2008/03/31/Nim_Chimpsky/