Koko: A Talking Gorilla
Koko A Talking Gorilla French Koko, le gorille qui parle is a 1978 documentary directed by Barbet Schroeder that focuses on Dr. Francine Penny Patterson and her work with Koko, the gorilla Patterson claims to have taught to communicate with humans using symbols taken from American Sign Language. The film was screened in the Un Certain Regard section at the 1978 Cannes Film Festival.
Source: Wikipedia