They might have some of the biggest brains, but dolphins really aren’t that clever, according to a scientist. Paul Manger, from a university in South Africa, says they use their big brains to stay warm, rather than for thinking. Manger claims the brain is made up of two types of cells — neurons and glia. Neurons do the thinking, while glia do things like keeping the brain warm. He claims dolphins have lots of glia and not many neurons. That could be because they live in the water, and need lots of glia to keep their brains going in the low temperatures.