Researchers have identified speech patterns in a gorilla, previously thought to be impossible for apes.
A gorilla named Koko became famous for her ability to learn sign language in order to communicate with her keepers. Researchers at the University of Wisconsin-Madison say that she is now displaying signs of being capable of speech.
Traditionally, it has been believed that vocal performance by apes has been limited to spontaneous noise expressed, for instance, at shock of seeing a predator or to intimidate a fellow mammal in a fight.
It was believed that beyond this, apes lacked the cognitive capacity and breathing control to engage in organised and premeditated speech.
Postdoctoral researcher Marcus Perlman at the University of Wisconsin-Madison and Nathaniel Clark at the University of California analysed 71 hours of video footage of Koko’s behaviour.
They say that they have “found examples of Koko performing nine different, voluntary behaviours that required control over her vocalisation and breathing.”
They concluded that “these were learned behaviours, not part of the typical gorilla repertoire.”
Mr Perlman said: “She doesn’t produce a pretty, periodic sound when she performs these behaviours, like we do when we speak. But she can control her larynx enough to produce 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.”