Apes may learn behaviour needed for human speech

The assumption is that humans are the only primates capable of speech, but one researcher who’s been studying Koko the gorilla says apes might be a lot closer to being able to vocalize their thoughts than we guessed.

Postdoctoral researcher Marcus Perlman at the University of Wisconsin-Madison and Nathaniel Clark at the University of California studied 71 hours of video footage of Koko interacting with her keepers and identified vocalizations thought to be impossible for gorillas.

As a result, he found repeated examples of Koko performing nine different, voluntary behaviors that required control over her vocalization and breathing.

Koko the gorilla, which has spent more than 40 years living immersed with humans at The Gorilla Foundation, is best known for a lifelong study to teach her a silent form of communication, American Sign Language.

Ever since the 1940s, when a couple attempting to raise a pair of chimpanzees like children failed to impart the ability of speech, scientists have assumed language to be a uniquely human evolutionary adaptation.

“The groundwork is there for apes to learn new communicative behaviors… and they appear to have some ability to transmit these behaviors through social learning and even transmit the behaviors across generations”, Perlman said. Koko, can blow her nose using a tissue, play wind instruments for fun, cough when researchers ask her to, and chatter into a telephone.

Clearly these behaviors were born of imitation, but they also display an ability to achieve vocal flexibility gorillas weren’t expected to have.

“She does not produce a pretty, periodic sound when she performs these behaviors, like we do when we speak”, said Perlman.

Previous to the discovery of Koko’s vocal talents, it was believed that gorillas could not control their vocalization and breathing to create specific sounds, leading to a limited array of calls that were used to communicate with others, mostly to signify danger, food, or moods. “She often looks like she plays her wind instruments for her own amusement, but she tends to do the cough at the request of Penny and Ron [her caretakers]”. The researchers added that these were things that Koko had learned and were not spontaneous noises. “It’s not as fine as human control, but it is certainly control”, Perlman said.

Perlman, whose observations are detailed in the journal Animal Cognition, says Koko is proof some of the abilities that enabled speech to evolve in humans were present in apes.

He says understanding how she uses her “voice” tells us something about humans. “The difference is just her environmental circumstances”.