Koko the gorilla, whose remarkable sign-language ability and motherly attachment to pet cats helped change the world’s views about the intelligence of animals and their capacity for empathy, has died in the United States at 46.

Koko was taught sign language from an early age as a scientific test subject and eventually learned more than 1,000 words, a vocabulary similar to that of a human toddler.

She became a celebrity and played along with the likes of William Shatner, Sting, Leonardo DiCaprio and Robin Williams.


In her home preserve, where she was treated like a queen, she once ran around with Williams’ eyeglasses and plyaed with Red Hot Chili Peppers star Flea’s bass guitar.

The Gorilla Foundation said the 127kg western lowland gorilla died in her sleep at the foundation’s preserve in California’s Santa Cruz mountains on Tuesday.

Koko was the not the first animal to learn sign language and communicate, but through books and media appearances she became the most famous.

Yet there was debate in the scientific community about how deep and human-like her conversations were.


Koko appeared in many documentaries and twice in National Geographic.

The gorilla’s 1978 National Geographic cover featured a photo that the animal had taken of herself in a mirror.

“Koko the individual was supersmart, like all the apes, and also sensitive, something not everyone expected from a ‘king kong’ type animal that movies depict as dangerous and formidable,” Emory University primate researcher Frans de Waal said in an email Thursday.

Koko watched movies and television with her handlers.

Her favourite book was “The Three Little Kittens” and her favourite movies included the Eddie Murphy version of “Doctor Doolittle” and “Free Willy”.


For her 25th birthday, she asked for and received a box of rubber snakes and in 1996 she asked to be a mother but did not achieve this despite attempts to introduce male partners.

Instead, she had a series of kittens as pets.

Koko was born on July 4, 1971 at the San Francisco Zoo.

Francine Patterson was working on her doctoral dissertation on the linguistic capabilities of gorillas and in 1972 started to teach Koko sign language.

Patterson and biologist Ronald Cohn moved Koko to their newly established preserve in 1974 and kept teaching and studying her, adding a male gorilla in 1979.