Apes Are Capable of Basic Speech

September 10, 2015 | Reece Alvarez

Koko the gorilla naps with her baby doll toy.
Photo credit: Courtesy of The Gorilla Foundation /

Renowned for her ability to use sign language to communicate, Koko the gorilla is one of the most famous apes in history and continues to break scientific ground with the latest discovery of her ability to expand her repertoire of vocalizations — a behavior previously thought impossible.

Koko, a 44 year-old western lowland gorilla, famous for her part in a life-long study to teach sign language to gorillas, has shown the ability to control rudimentary vocal and breathing-related behaviors — possibly upending long-held beliefs about the evolutionary origins of human speech.

"I went there with the idea of studying Koko's gestures, but as I got into watching videos of her, I saw her performing all these amazing vocal behaviors," says Marcus Perlman, a postdoctoral researcher at the University of Wisconsin-Madison who studies the creation and evolution of languages.

According to an announcement made by the University of Wisconsin-Madison, Perlman and collaborator Nathaniel Clark of the University of California, Santa Cruz, watched 71 hours of video of Koko interacting with other researchers. They found repeated examples in which she performed nine different, voluntary behaviors that required control over her vocalization and breathing. These were learned behaviors, not part of the typical gorilla repertoire.





Koko can reportedly “blow a raspberry” (or blow into her hand) when she wants a treat, blow her nose into a tissue, play wind instruments, and huff moisture onto a pair of glasses before wiping them with a cloth. Impressively, she can even mimic phone conversations by chattering wordlessly into a telephone cradled between her ear and the crook of an elbow.

Perlman believes that Koko has been able to pick up these behaviors through the extensive time she spends interacting with humans.

"Presumably, she is no more gifted than other gorillas," he says. "The difference is just her environmental circumstances. You obviously don't see things like this in wild populations."

Koko was born was born in the San Francisco Zoo and has spent her life in the company of humans. In 1972, she became the focus of a study by psychologist Francine “Penny” Patterson to teach Koko sign language — requiring many hours of interaction a day with Patterson and fellow researcher Ron Cohn.





Koko can now understand more than 1,000 signs in American Sign Language, or what in her case has been called, “gorilla sign language,” and has shown an understanding of more than 2,000 words.

This is all on top of her other incredible displays of emotions and intelligence, from moments of empathy to creating paintings and even adopting a cat.

Prior to the study by Perlman, it was believed that the range of sounds an ape could make was fixed.

It was believed that, “the calls apes make pop out almost reflexively in response to their environment — the appearance of a dangerous snake, for example,” according to the university.

"Decades ago, in the 1930s and '40s, a couple of husband-and-wife teams of psychologists tried to raise chimpanzees as much as possible like human children and teach them to speak. Their efforts were deemed a total failure," Perlman says. "Since then, there is an idea that apes are not able to voluntarily control their vocalizations or even their breathing."



While these actions seem mundane, they could have significant implications for the evolution of human speech and the rights of animals.

"This idea says there's nothing that apes can do that is remotely similar to speech," Perlman says. "And, therefore, speech essentially evolved — completely new — along the human line since our last common ancestor with chimpanzees."

But the behaviors Koko has displayed suggests that “some of the evolutionary groundwork for the human ability to speak was in place at least by the time of our last common ancestor with gorillas, estimated to be around 10 million years ago,” according to the university.

"Koko bridges a gap," Perlman says. "She shows the potential under the right environmental conditions for apes to develop quite a bit of flexible control over their vocal tract. It's not as fine as human control, but it is certainly control."

Orangutans have also demonstrated some impressive vocal and breathing-related behaviors, according to Perlman, indicating that the whole great ape family may share the abilities Koko has learned to tap into.


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