Gorilla who mastered sign language dies

A gorilla who learned to communicate in sign language has died in the US at the age of 46.

Western lowland gorilla Koko died at the Gorilla Foundation's preserve in California's Santa 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.

The gorilla, who was said to have an IQ of between 75 and 95, could understand 2000 words of spoken English.

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

A foundation spokesman said it will honour Koko's legacy with a sign language application for the benefit of gorillas and children, as well as other projects.