Did chimp from 1970s experiment die of a ‘broken heart’?

True story: As part of a scientific project, a chimp born in captivity in 1973 was raised by a family in New York City and learned to communicate through sign language. But the chimp couldn't fit in with humans and, when returned to life with other chimps, couldn't fit in as a primate either.

Ultimately, after a tragic turn that led him to be a caged test subject in a medical lab, the chimp, named Nim Chimpsky, died prematurely at 26. In the wild, apes can live to be as old as 60.

The controversial experiment from the 1970s is being revisited in the film "Project Nim," which had a limited theatrical release last year and is being shown on HBO Dec. 20.

Nim was taken from his mother at the Institute for Primate Studies in Oklahoma and brought to New York City by Columbia psychology professor Herb Terrace. Terrace had a former student, Stephanie LaFarge, raise him as she had her other seven children, even breast-feeding him.

Nim learned to sign and do human stuff, like sleep in a bed and drink beer. He became a media star, landing on the cover of New York magazine.

But he also grew bigger and more aggressive. Eventually, after attacking his caretakers, he was moved back to the Institute for Primate Studies. When that facility ran out of money, he was moved again to a New York University lab, where he was caged and subjected to experiments. A public outcry led him to be released to an animal sanctuary in Texas, where he died in 2000.

Terrace recently defended his research to ABC News, noting that it was conducted before the scientific community had become sensitized to the issue of animal rights. "Everyone I know was blind to this issue," he said.

Bob Ingersoll, one of Nim's caretakers, told ABC News that Nim's early death could have been caused by stress or, sadly, "it might actually be fair to say he died of a broken heart."