Koko (gorilla)

Hanabiko "Koko" (July 4, 1971 – June 19, 2018) was a female western lowland gorilla. Koko was born in San Francisco Zoo, and lived most of her life 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 naming him "All Ball", which the public perceived as her ability to rhyme.

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). This puts Koko's vocabulary at the same level as a three-year-old human. 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.

As with other great-ape language experiments, the extent to which Koko mastered and demonstrated language through the use of these signs is debated. Koko is said to have understood nouns, verbs, and adjectives, including abstract concepts like "good" and "fake", and was able to ask simple questions. However, it is generally accepted that she did not use syntax or grammar, and that her use of language did not exceed that of a young human child. Some experts, including human-primate communications expert Mary Lee Jensvold, claim that Koko "[used] language the same way people do" and she scored between 70 and 90 on various infant IQ scales. However, other experts such as primatologist Barbara J. King have criticized Patterson for excessively anthropomorphizing Koko. Linguists such as Geoffrey K. Pullum and fellow ape language researcher Herbert S. Terrace have questioned Patterson's research methods and claims of Koko's language competency, as well as the degree to which Koko's utterances could be interpreted as language.