Koko: gorilla who ‘spoke’ in sign language dies aged 46

Koko, the “talking” gorilla who reportedly learned more than 1,000 words in sign language, has died in her sleep at the age of 46.

“Koko touched the lives of millions as an ambassador for all gorillas and an icon for interspecies communication and empathy,” the Gorilla Foundation said in a statement announcing her passing. “She was beloved and will be deeply missed.”

Koko “is perhaps the most famous product of an ambitious field of research, one that sought from the outset to examine whether apes and humans could communicate”, Slate’s Jane C.Hu wrote in 2014.

Born in captivity at San Francisco Zoo in 1971, the western lowland gorilla began working with animal psychologist  Francine “Penny” Patterson in 1972.

They would remain together for the next four and half decades -  first at Stanford University, where Patterson gained a PhD in 1979, and then to a permanent home in California’s Santa Cruz Mountains.

As well as reportedly mastering 1,000 signs, Koko was “said to have understood some 2,000 words of spoken English”, CNN reports.

However, some experts expressed scepticism about Koko’s true intelligence, suggesting that she “simply learns to sign because she’ll be rewarded – known as operant conditioning”, The Daily Telegraph reported in 2016.

Koko became an “icon for inter-species communication and empathy”, ABC reports, featuring in documentaries as an example of animal intelligence.

When comedian and actor Robin Williams died in 2014, a video of his 2001 meeting with Koko quickly went viral. The clip showed the two hugging, playing and laughing with one another during an encounter Williams later described as “awesome and unforgettable”.

She was the subject of a string of books, including Koko’s Kitten, a children’s book about her friendship with a cat, and counted Leonardo Di Caprio and William Shatner among her admirers.