T he divers and scientists lucky enough to spend time among the world’s whales often find themselves wondering what is going on in the oversized brains of the sea’s largest inhabitants.

We know they have the biggest brains in the animal kingdom, with a sperm whale’s weighing more than five times that of an average human brain. A bottlenose dolphin’s encephalization quotient, a measure of brain to body size ratio, is second only to that of a human.