" Brains are notoriously selfish organs. They give themselves priority access to everything they require—from blood-flow to warmth, nutrients and oxygen. During times of bodily stress, our brains will shut down one organ after another, even to the point of damaging them—before depriving themselves. Brains are also greedy. They make up just 2 per cent of our body weight, yet take 20 per cent of the energy we use. "

― Tim Flannery , Here On Earth: An Argument For Hope