Why does the brain have two sides?

The cerebrum is divided lenghtways into two halves, called cerebral hemispheres. Each side of the brain controls the opposite side of the body.For example, if you move your right leg, the instructions for nthat movement come from the left side of the brain. The nerve cells that carry messages from the brain cross over at the base of the brain. In most people, the left side controls speaking, writing and logical thought, while the right side controls artistic abilities and creative thinking. Most people seem to use one side more trhan the other. This is why some people seem to be more artistic than others, or are better at scientific and mathematical thinking. Usually, the left side of the brain is more dominant as far as movement is concerned, which is why most people are right-handed. About 10 % of people are left-handed.