For nearly five decades, psychologist Francine Patterson taught a western lowland gorilla named Koko a modified sign language — and Koko reportedly learned more than 1,000 signs, understood 2,000 spoken words, and mourned when her kitten was killed by a car

For nearly five decades, psychologist Francine Patterson taught a western lowland gorilla named Koko a modified sign language — and Koko reportedly learned more than 1,000 signs, understood 2,000 spoken words, and mourned when her kitten was killed by a car

For most of her life, a western lowland gorilla named Koko was among the best-known non-human animals on the planet. She appeared twice on the cover of National Geographic. She sat with Robin Williams and taught Mister Rogers a sign for love. And she was said to speak, after a fashion, in a modified sign language that let her tell the people around her when she was happy, hungry, or sad. Over nearly five decades, Patterson and the Gorilla Founda…