New Scientist Life's top 10 greatest inventions - Features

New Scientist Life's top 10 greatest inventions - Features: "THE BRAIN
BRAINS are often seen as a crowning achievement of evolution - bestowing the ultimate human traits such as language, intelligence and consciousness. But before all that, the evolution of brains did something just as striking: it lifted life beyond vegetation. Brains provided, for the first time, a way for organisms to deal with environmental change on a timescale shorter than generations.

A nervous system allows two extremely useful things to happen: movement and memory. If you're a plant and your food source disappears, that's just tough. But if you have a nervous system that can control muscles, then you can actually move around and seek out food, sex and shelter.

With brains come senses, to detect whether the world is good or bad, and a memory. Together, these let the animal monitor in real time whether things are getting better or worse. This in turn allows a simple system of prediction and reward. Even animals with really simple brains - insects, slugs or flatworms - can use their experiences to predict what might be the best thing to do or eat next, and have a system of reward that reinforces good choices.

The more complex functions of the human brain - social interaction, decision-making and empathy, for example - seem to have evolved from these basic systems controlling food intake. The sensations that control what we decide to eat became the intuitive decisions we call gut instincts. The most highly developed parts of the human frontal cortex that deal with decisions and social interactions are right next to the parts that control taste and smell and movements of the mouth, tongue and gut. There is a reason we kiss potential mates - it's the most primitive way we know to check something out.