Koko was a female western lowland gorilla known for having learned a large number of hand signs from a modified version of American Sign Language (ASL). Koko was born to her mother, Jacqueline and father, Bwana on July 4, 1971, at the San Francisco Zoo. Koko was the 50th gorilla born in captivity and one of the first gorillas accepted by her mother in captivity. Koko remained with her mother until the age of one when she was taken to the zoo's hospital to be treated for a life-threatening illness. Patterson originally cared for Koko at the San Francisco Zoo as part of her doctoral research at Stanford University after Koko developed a life-threatening illness. Koko was loaned to Patterson under the condition that she would spend at least 4 years with Koko. Eventually, Koko remained with Patterson, supported by The Gorilla Foundation, which Patterson founded to support gorilla research and conservation. Koko lived most of her life in Woodside, California, at The Gorilla Foundation's preserve in the Santa Cruz Mountains. The name "Hanabiko" (花火子), lit. 'fireworks child', is of Japanese origin and is a reference to her date of birth, the Fourth of July. Koko gained public attention upon a report of her having adopted a kitten as a pet and creating a name for him. Her instructor and caregiver, Francine Patterson, reported that Koko had an active vocabulary of more than 1,000 signs of what Patterson calls "Gorilla Sign Language" (GSL). In contrast to other experiments attempting to teach sign language to non-human primates, Patterson simultaneously exposed Koko to spoken English from an early age. It was reported that Koko understood approximately 2,000 words of spoken English, in addition to the signs. Koko's life and learning process has been described by Patterson and various collaborators in books, peer-reviewed scientific articles, and on a website.
