Extract: Notes on the Intelligence of Whales

........ It has been said that whales have big brains simply because they are big animals. That is certainly not so. Some very big animals, such as the whale shark and the basking shark, have small brains. It would better be argued the other way round: the body of the whale is big because it has a large brain. If an animal turns its head excessively rapidly its fragile brain tissue can be mechanically damaged. A big brain is more easily damaged than a small one. So animals with big brains must not be able to turn their heads too fast. Big bodies cannot spin as fast as small ones, just as a super-tanker cannot turn as rapidly as can a dinghy. To help make sure the brain will be protected the neck of the large species is inflexible.

And cetaceans probably do not need big brains simply to process sonar signals: bats do that very well with quite small brains. But big brains surely do not evolve without any function. So, the whales' brains must be used for something else as well? The outstanding question is: "For what?".