““Dolphins have one of the highest ratios of brain size to body mass in the animal kingdom. Measured in this way, a dolphin’s brain is second in size only to that of a human’s, and well above that of our closest genetic relative, the chimpanzee. A large brain-to-body size ratio is often considered a hallmark of intelligence, although it’s not the only factor. But it is something we humans celebrate in ourselves and regard as key to the flowering of human intelligence.””