Watch Koko the Gorilla Use Sign Language in This 1981 Film | National Geographic

[Music] Near San Francisco, California, a fascinating and now controversial experiment has been underway since 1972. Research psychologist Penny Patterson is teaching lowland gorillas Koko the American Sign Language of the deaf. Dr. Patterson claims Koko has a working vocabulary of about 450 signs and that because Patterson also talks while signing, Koko understands hundreds of spoken words as well.

For many years, researchers have been fascinated with the language possibilities in chimpanzees. Patterson is the first to work with gorillas. In Koko's mobile home, not far from Patterson's house, even breakfast is a time for work.

"Okay, this is hot. You stir, Koko. It needs to be stirred."

"Okay, now try it."

Michael is in an adjoining room of the trailer. A trainer works with seven-year-old Michael. It is hoped that one day he and Koko will make a connection.

"And you find something soft? There's something soft here."

"Yes, that's soft. Yeah, yes. Feel it. Nice. What color is that?"

"It's orange."

"Very good! Apple. Okay, first let's look at... let's get a new one. Take that one out. Let's see which one would you like to look at, Koko? We have three new ones. Which one?"

"The monkeys."

"Okay, the monkeys. Monkeys. All right, let's see. I'll get them up. Okay, here, let's change this one. Can you tell me about what you see? Can you tell me a little about that? What do you see?"

"Margie."

"Trouble? I've gotta see if there's someone in here that looks like Archie. Just with it."

"Well, there's a monkey swimming on this one."

"Just, just be patient. Be patient. I have to look, Penny."

"Margie, somehow... well, there's a girl that looks like Margie."

"Yes, there's a girl feeding a monkey and she looks a bit like Margie."

"Yeah, what's wrong here? Is there anything wrong with reading readiness tests used with human children?"

Paterson tests Koko's grasp of concept.

"That's good. And then you say the tree?"

"Well, you showed me the trees."

"That's wrong, right? Anything else?"

"Yes, they have that the lady and the toy."

"That is a bit weird. Pretty neat. Look, there are stars. Can you find the eyes in this picture?"

"Those are the eyes."

Critics of a plan which studies claim that the animals are not creating true language, that it is merely mimicry or responses evoked by inadvertent cues. Patterson is quick to point out that Koko often signs to herself.

In this case, several repetitions of "flower" and "hat" clearly. Patterson says something more complex than mimicry is involved in the mental capacities Koko displays. Perhaps criticism will abate as apes begin to sign to each other. Patterson reports instances of this between Koko and Mike and hopes they will eventually pass on their abilities to their offspring.

But work aside, at day's end, there is time now just for fun.

"You're thirsty today because it's hot."

"More! I think you need more. More water."

"Okay, that's enough."

Linguists and philosophers argue the definition of language and whether it is uniquely human. In academic corridors, the debate will go on. But for now, few can deny we have glimpsed a mind more fascinating than ever imagined before.

By knowing more about gorillas, about their intelligence, how sensitive they are, how perceptive they are, we can hope to convey the importance of saving views as a species to people who are living with them and are competing rhythm.

If they realize how similar to man they are, perhaps conservation efforts will be enhanced. [Music]