The left and right side of the brain are involved in different tasks. This functional lateralization and associated brain asymmetry are well documented in humans. Scientists now challenge the long-held notion that the human pattern of brain asymmetry is unique. They found the same asymmetry pattern in chimpanzees, gorillas, and orangutans. However, humans were the most variable in this pattern. This suggests that lateralized, uniquely human cognitive abilities evolved by adapting a presumably ancestral asymmetry pattern.