Pbs: A Conversation With Koko

From the site: "It was supposed to be a short-term research project. Instead, it became a lifetime of learning. Along the way, people learned to see gorillas in a whole new light. 'A Conversation with Koko' tells the remarkable story of Dr. Francine 'Penny' Patterson's nearly 30-year relationship with Koko, a western lowland gorilla she taught to communicate in sign language."