Koko mastered a thousand words and was the subject of many reports that made her famous. She died in California at the age of 46.
Koko, a captive-bred gorilla who became world-famous for her mastery of sign language, died in California, the Gorilla Foundation announced. She was 46 years old.
The primate, who was born on July 4, 1971, in the San Francisco Zoo, died "in her sleep," the foundation said in a statement.
"Koko's ability for language and empathy opened the minds and hearts of millions of people," the foundation said, calling her "an icon of interspecies communication.”
In 1972, an animal researcher and psychologist, Francine Patterson, began teaching Koko sign language, and then the gorilla continued her training at Stanford University, where the foundation, dedicated to the study of gorillas in captivity, was established.
Koko, who mastered a thousand words, was the subject of many reports that brought her to fame. Starting with the National Geographic coverage in October 1978, which showed her taking a picture of herself and looking in a mirror.
Koko enjoyed reading books with pictures based on "The Three Kittens" and "The Puss in Boots" so much that in 1983 she started asking for a pet cat. She refused stuffed cats that were given to her as substitutes using the "sad" sign. After a while, she was allowed to have a real cat as a pet.
When she received the cat, she repeated the sign of "good" over and over again, clearly happy.
She named her kitty "All Ball" and played with him until the cat got fed up and slipped out of her arms, pointing to it as "annoying" and "cat", and her relationship even inspired a children's book that became a classic, "Koko's kitten".
When the cat died, hit by a car, Koko showed her pain for months.
When All Ball was tragically hit by a car, Koko started whining with a sound that gorillas make when they are sad. In 1978 and 1985 she appeared on the cover of National Geographic, where the world admired her for her ability to learn signs and her love for cats.
The gorilla also loved painting and participated in online conversations with many fans, the world will for sure miss Koko.