In 1972 Dr. Francine Patterson began to explore the question of whether a gorilla could learn to communicate through sign language. The story of how Penny won Koko’s trust and gradually began to teach her words is so heart-warming, and is richly illustrated with color photographs. Having so much success with Koko, she began to teach another gorilla, Michael, and the two gorillas became friends.

At the end of the book Dr. Patterson writes:

“There are only a few thousand lowland gorillas like Koko and Michael left in the world. We have just begun to understand how smart and gentle these animals really are, and we can learn much more. We must protect them so they do not become extinct.”

She will have no trouble getting readers of the books about Koko on board. ( )