Much has been written about 44-year-old Koko, the gorilla who allegedly knows more than a thousand signs in American Sign Language, as well as a modified sign language she made up herself called “Gorilla Sign Language.” (She’s pictured above with Robin Williams, and was reportedly saddened over news of his death.)
Since she was a baby, she’s been trained by gorilla researcher Francine “Penny” Patterson, who claims Koko has a mastery of sign language and shows an understanding of several concepts, including self recognition, that other gorillas in captivity don’t.
There’s quite a lot of press about Koko and her signing, but not as much research into her other than by her trainers at the Gorilla Foundation. Marcus Perlman, a postdoctoral researcher at the University of Wisconsin, started watching videos of Koko in 2011 to observe her hand gestures. What he saw instead was Koko performing vocal and breathing behaviors that suggest she’s trying to speak.
According to the Daily Mail:
“She doesn’t produce a pretty, periodic sound when she performs these behaviours, like we do when we speak,” Dr. Perlman says. “But she can control her larynx enough to produce a controlled grunting sound.”
Here she is trying to talk to Mr. Rogers in 1998:
Researchers have seen Koko blowing a raspberry, blowing her nose into a tissue, mimicking phone conversations, and even coughing, which is difficult for apes because they can’t close off their larynx. Primatologists currently think each species of ape has a limited “vocal repertoire,” which makes them incapable of producing sounds outside of their limited range. Perlman watched 71 hours of video of Koko, and saw her repeatedly performing nine different vocal behaviors that would mean she has control over her voice in a way previously thought impossible for gorillas.
“She shows the potential under the right environmental conditions for apes to develop quite a bit of flexible control over their vocal tract,” Perlman explained. “It’s not as fine as human control, but it is certainly control.”
All of this suggests to the researchers at the Gorilla Foundation that great apes are capable of developing the ability to speak. While that remains to be seen, Koko does demonstrate that primates are far more complex than they’re readily given credit for. The Non-Human Rights Project is one example of a recent movement trying to grant personhood status to apes, in order to legally protect them from being tested and experimented on. Hopefully further research into Koko’s speech will lead to the better treatment of primates in the United States.