During human evolution, our forebrain became larger as our cerebral cortex increased in size. This means it had to become more folded to fit inside the skull. This gives the outside of the human brain its ‘walnut’ appearance. Humans have a larger cerebral cortex than any other animal.
The right side (hemisphere) of your brain controls the left side of your body, and the left hemisphere controls the right side. Although the two sides of the brain look like mirror images of each other, they are different. In most people, the left hemisphere is important for language, maths and reasoning, whereas the right is more important for emotion, recognising faces and music.