Pioneering gorilla Koko dies at 46

Koko asks for an orange from mentor Penny Patterson by extending her left arm away from her body.
Photo: Bettman/Getty Images

Koko, the western lowland gorilla who amazed with her vocabulary and communication skills, died in her sleep Wednesday at the age of 46 at The Gorilla Foundation in San Francisco.

Why it matters: Koko, chosen for a psychology research project when she was just one year old, shattered perceptions of language abilities for non-human primates.