Koko, the world famous Gorilla known for her language skills and love of kittens, has passed away at the age of 46.
“The Gorilla Foundation is sad to announce the passing of our beloved Koko,” the research center said in a statement. “Her impact has been profound and what she has taught us about the emotional capacity of gorillas and their cognitive abilities will continue to shape the world.”
Koko died in her sleep early on Tuesday morning.

Koko was born on July 4, 1971. She was originally given the name Hanabi-ko, which is Japanese for “fireworks child.”
As an infant, Koko was selected by psychologist Francine “Penny” Patterson for a language research project. Over the course of the next four decades, Koko made headlines around the globe for her ability to learn language and communicate through sign.
Koko was featured in a magazine article profiling her loving relationship with a small kitten, Ball. “Famously, Koko felt quite sad in 1984 when her adopted kitten Ball was hit by a car and died,” Barbara J. King wrote for NPR. “How do we know? Here is nonhuman primate grief mediated through language: In historical footage in the film, Patterson is seen asking Koko, ‘What happened to Ball?’ In reply, Koko utters these signs in sequence: cat, cry, have-sorry, Koko-love. And then, after a pause, two more signs: unattention, visit me.”
In 2001, Koko met and befriended actor and comedian Robin Williams. At the time Koko said she recognized Williams’ face from a movie. The pair laughed and played together for an afternoon. Thirteen years later, Koko mourned the actor’s death.