Koko, the western lowland gorilla who mastered sign language and displayed an empathy that won over the hearts of millions, has died in California. She was 46.
The lovable primate died in her sleep at the Gorilla Foundation’s preserve in Santa Cruz Tuesday, the organization said.
"Koko touched the lives of millions as an ambassador for all gorillas and an icon for interspecies communication and empathy," a statement by the foundation said. "She was beloved and will be deeply missed."
Koko was born Hanabi-ko, Japanese for “fireworks child,” at the San Francisco Zoo on July 4, 1971.
When she was a year old, Koko was given to animal psychologist Francine “Penny” Patterson, originally as a loan for her doctoral research, but the pair was never separated and Patterson became Koko’s instructor and caregiver.
Patterson reported that Koko understood more than 1,000 signs of a modified version of American Sign Language known as Gorilla Sign Language, and could understand approximately 2,000 words of spoken English in addition to the signs.
Koko also gained fame for her capacity for empathy, as the world came to recognize how loving a gorilla could be after watching her interact with others, the foundation said.
Koko was especially maternal toward kittens, and had several throughout her lifetime.
She appeared in many documentaries and on television, including "Mister Rogers’ Neighborhood." She also met with the late comedian Robin Williams, who called his interaction with Koko in 2001 a "mind-altering experience."
“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,” the Gorilla Foundation said. “The foundation will continue to honor Koko’s legacy and advance our mission with ongoing projects including conservation efforts in Africa, the great ape sanctuary on Maui, and a sign language application featuring Koko for the benefit of both gorillas and children."