Koko, the gorilla who knew sign language, dies at 46

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Koko, the gorilla who mastered sign language and counted the actor Robin Williams and Red Hot Chili Peppers bassist Flea among her friends, has died at age 46. June 20, 2018

 Koko, the gorilla who mastered sign language, has died.

The Gorilla Foundation says the 46-year-old western lowland gorilla died in its sleep at the foundation's preserve in California's Sana Cruz mountains on Tuesday.

Koko was born at the San Francisco Zoo, and Dr. Francine Patterson began teaching the gorilla sign language that became part of a Stanford University project in 1974.

VIDEO: The life of Koko, the Bay Area's beloved gorilla

The foundation says Koko's capacity for language and empathy opened the minds and hearts of millions.

Koko appeared in many documentaries and twice in National Geographic. The gorilla's 1978 cover featured a photo that the animal had taken of itself in a mirror.

The foundation says it will honor Koko's legacy with a sign language application featuring Koko for the benefit of gorillas and children, as well as other projects.