Nature (1982) : 17x16

Profiling the 28-year-old lowland gorilla Koko, who communicates by sign language with her mentor, Francine Patterson. Koko, who understands English, has “a good sense of humor,” says Patterson, and “a strong sense of self.” She's also seen painting and watching TV, and playing with male gorillas Michael and Ndume at Patterson's Gorilla Foundation in Northern California.