Apes may learn behaviour needed for human speech

Washington: Challenging the perception that humans are the only primates with the capacity for speech, new research has found that gorillas too can learn new vocal and breathing-related behaviours -- key requirements for human speech. The study followed the behaviour of Koko the gorilla, best known for a lifelong study to teach her a silent form of communication, American Sign Language.

Koko has spent more than 40 years interacting with humans. Marcus Perlman from University of Wisconsin-Madison in the US, and his collaborator sifted 71 hours of video of Koko interacting with humans and found repeated examples of Koko performing nine different, voluntary behaviours that required control over her vocalisation and breathing.

These were learned behaviours, not part of the typical gorilla repertoire. Among other things, the researchers watched Koko blow her nose into a tissue, play wind instruments, and mimic phone conversations by chattering wordlessly into a telephone cradled between her ear and the crook of an elbow. Koko can also cough on command, not particularly ground-breaking human behaviour, but impressive for a gorilla because it requires her to close off her larynx, the researchers found.