Koko the gorilla died today after having lived to the age of 46, having spent her life famous for mastering American Sign Language.
According to The Gorilla Foundation, Koko was born at the San Francisco Zoo on July 4, 1971. Animal psychologist Francine "Penny" Patterson began teaching Koko to sign while she was a graduate student in 1972, work which eventually became part of a project at Stanford University.
The gorilla, was believed to have an IQ between 75 and 95 and to understand 2,000 words of spoken English.
Her remarkable ability to sign landed her on the cover of National Geographic twice - in 1978 which featured a photo she took of herself in a mirror and again in 1985 showing an image of her mourning the death of one of her pet kittens.
Koko was supported and looked after by the Gorilla Foundation, known for their "Project Koko" the "longest interspecies communication study in history".
The foundation says that Koko's range to learn the sign language and her soul brimming with empathy opened the minds and hearts of millions.
"She was beloved and will be deeply missed", it said.
Her love of animals spawned the children's book "Koko's Kitten" and her own branded line of toys.
"It was awesome and unforgettable", said the actor, who killed himself in August 2014.
"At the end of the day, Koko became very somber, with her head bowed and her lip quivering".
Koko was among a handful of primates who could communicate using sign language; others included Washoe, a female chimpanzee in Washington state, and Chantek, a male orangutan in Atlanta.
Koko once met Robin Williams in a now-famous encounter.
Koko painted objects in her environment but also expressions of her thoughts and emotions.