Koko is a gorilla who knows sign language.

The beginning

Koko was originally loaned to Francine Patterson for her doctoral research, but has stayed with Patterson ever since. Koko lived with another gorilla, Michael, who also learned sign language but died in 2000. She now lives with a male gorilla, Ndume.

About Koko

Koko understands approximately 2,000 words of spoken English, in addition to the signs. Koko is able to understand more than 1,000 signs of what Patterson calls "Gorilla Sign Language".