Koko the gorilla, who is said to have been able to communicate by using more than 1,000 hand signs, has died in California at the age of 46.
Instructors taught her a version of American Sign Language and say she used it to convey thoughts and feelings.
The abilities of the gorilla, who also apparently understood some spoken English, were documented by animal psychologist Francine Paterson.
She adopted and named pets, including a kitten she called All Ball.
“Koko – the gorilla known for her extraordinary mastery of sign language, and as the primary ambassador for her endangered species – passed away yesterday [Wednesday] morning in her sleep at the age of 46,” a Gorilla Foundation press release said.
“Koko touched the lives of millions as an ambassador for all gorillas and an icon for interspecies communication and empathy. She was beloved and will be deeply missed.”
The gorilla, who was said to have an IQ of between 75 and 95, could understand 2,000 words of spoken English. The average IQ for humans on many tests is 100, and most people score somewhere between 85 and 115.
She was born at the San Francisco Zoo and lived most of her life at the Gorilla Foundation in California.