In the 20th century and beyond, several research programs explored the ability of apes to communicate with human sign language, including primate celebrities such as Washoe the chimpanzee, Nim ...

Koko the gorilla, whose remarkable sign-language ability and motherly attachment to pet cats helped change the world's views about the intelligence of animals and their capacity for empathy, has died ...

Koko, the gorilla who mastered sign language, died at the age of 46. Koko, the gorilla who mastered sign language and became a pop-culture phenomenon, will be laid to rest Saturday in a ceremony at an ...