" Wise's accounts of animals' mental abilities are fascinating and thought-provoking. But in the end, it wasn't their relative autonomy scores that swung my sympathies. It was the description of Koko making a joke; of a mother elephant involving her youngster in a game so she could complete a task. It was the account of Alex, the parrot, left at the vet for surgery, calling after her keeper, "Come here. I love you. I'm sorry. I want to go back.""