Postdoctoral researchers at the University of Wisconsin, Madison, have been able to identify that Koko, a 44-year old, female western lowland gorilla, famous for her ability to communicate with her keepers through sign language, is now showing signs of being capable of speech as well.
Marcus Perlman, one of the researchers who has been working at the Gorilla Foundation which housed Koko since 2011, shared this with the Daily Mail: "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." The behaviors he was referring to were actually learned behaviors and were not part of a "typical gorilla repertoire," Perlman and the other researchers discovered.
It was the long standing belief of primatologists that each species of ape have limited "vocal repertoire" which limits them from learning new sounds beyond a particular range. The same theory connotes that the development of verbal language is a characteristic unique to human beings, but Koko might just be able to disprove that. She has an extensive command of the modified American Sign Language (ASL) and knows more than 1,000 signs in the "Gorilla Sign Language" (GSL).
While she uses no grammar or syntax yet, she is capable of formulating new phrases from existing words. Francine Patterson, her primary caretaker, for instance, illustrates that to be able to express the word ring, Koko combines the signs for "bracelet" and "finger."
Perlman said that while Koko does not produce a pretty, periodic sound when she performs such behaviours, the gorilla can control her larynx enough to come up with a "controlled grunting sound."
"Koko bridges a gap. She shows the potential under the right environment 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," said Perlman.
