The James Marsh film, "Project Nim," explores the life of the primate — cheekily named after linguist Noam Chomsky — that was raised like a human child and taught American Sign Language in the 1970s in an effort to prove that language was not exclusive to humans.
Four decades later, the questions raised by the experiment are still far from settled.
As an infant, Chimpsky was taken to live with the LaFarge family in New York City. There, among seven human "siblings," he was raised just as a human child, taught to sign, dressed in sweaters, even breastfed from his human foster mother.
"It was really 'Brady Bunch Plus Chimp,' with a mess of children coming and going," said Elizabeth Hess, whose book "Nim Chimpsky: The Chimp Who Would Be Human" served as the foundation for the film.
The arrangement was intended to settle a longstanding feud between Chomsky and psychologist B.F. Skinner about whether language was the key factor that separated humans from other animals, Hess said: "Skinner argued that even chimps could acquire language and Chomsky said language was exclusive to humans."
One of Skinner's disciples, a cognitive scientist named Herbert Terrace, decided to prove Chomsky wrong using the linguist's own principles.
Other researchers had already reported that a female chimp named Washoe could not only use words in sign language but was structuring her responses too — a sign that the broad strokes of syntax were emerging in her mind. Terrace wanted to use more rigorous methods to prove that point, and perhaps take it further.
After the four-year study, however, Terrace said he found quite the opposite. He and his colleagues at Columbia University reported in a November 1979 edition of the journal Science that there was little evidence the chimpanzee was engaging in anything approaching language.
"Everybody thinks I'm a bad guy, but I started out trying to show that chimps could use sign language and at the last minute I saw something that changed my mind," said Terrace, now a professor at Columbia University.
Nim seemed to use words when he was in search of reward — whether it was a cat to cuddle, a bite to eat or even a cigarette to puff on — and even those words that he appeared to use spontaneously were subtly prompted responses, Terrace argued.
Also, Terrace added, things that seemed like sentences because they contained a proper word order, such as "Me hug cat," often broke down in longer chains, such as the 16-word "Give orange me give eat orange me eat orange give me eat orange give me you."
But some other researchers were not convinced.
Among them was Roger Fouts, the psychologist at Central Washington University who began teaching the chimpanzee Washoe to use sign language in the late 1960s. He argued that Terrace's study was not designed in a way that would have maximized Nim's language capabilities.
"He blamed [the failures] on the biology, rather than looking at his own procedures," Fouts said.
After the experiment ran its course, Nim was sent to Oklahoma to live with other chimps. It was the first time in his entire life that he had met another chimpanzee.
Later, protests broke out over plans to sell Nim to a lab that would have injected him with a hepatitis virus for a research study. Instead he was sent to retire at the Black Beauty Ranch in Texas.
Neither camp has budged in its views since the Project Nim experiment. Fouts sees different types of animal communication as a continuum, with language lying somewhere on it.
"Most people like to hear how special they are, how unique they are. Well, we're unique, but so are cockroaches and birds and pear trees," Fouts said. "We have to look for similarities too, because too often, if you're just looking for the differences, we're not finding much out about ourselves or about our fellow animals."
Terrace still writes off as wishful thinking any effort to show that chimpanzees can acquire language. He mentioned a short story by Franz Kafka titled "A Report for an Academy," in which an ape describes attempts to make him act like a human.
"I'll say it again: Imitating human beings was not something which pleased me," Kafka's ape confesses. "I imitated them because I was looking for a way out, for no other reason."
As for Nim, even though he escaped the viral injection, he died in 2000 at the relatively young age of 26, Hess said. He'd suffered from an enlarged heart.
The film, which premiered Thursday night in Park City, Utah, will be screened again Saturday, Sunday, Wednesday and Friday. All showings are fully booked. HBO purchased all rights to the film ahead of its premiere and said it planned to release the documentary in theaters and on DVD.