Intelligence in your Hand
Some people feel left-handers are more intelligent. Right-handers might disprove but there are theories which indicate that the hand you use determines your intelligence too.
The brain is divided into two halves, right and left. When the left hemisphere of the brain is dominant the person becomes right handed, and vice versa for the right hand. The dominant hemisphere perceives the perceptions of the opposite side of the body. That means when there is pain in the right hand it is perceived in the left hemisphere and similar reaction happens in the right hemisphere.
In right-handed people an area called the Wernicke's area, which lies on the left side of the brain, is highly developed. In case of a left-handed person, it develops on right side of the brain. Wernicke's area can actually be called "interpretive area". This area is also known as general interpretive area, the Gnostic area, the knowing area, and so on. However, it is best known as Wernicke's area in honor of the neurologist who first described its special significance in intellectual process.
In about 95% of all individuals the left hemisphere is dominant one. The reason is, in more than one half of the babies Wernicke's area of the brain is as much as 50% larger in the left hemisphere than in right. Being larger at one side it develops further. The part of Wernicke's area present on the right side becomes inactive and becomes recessive. Most of the times, right from the time of birth the interpretive area is in left hemisphere it explains why more than half of the population is right handed.
In strongly left-handed and strongly right-handed persons the Wernicke's area becomes recessive. However, in ambidextrous (using both the hands) the Wernicke's area in both the hemisphere is active. The capability of performing complex functions depends on the Wernick's area, as it plays vital role in interpretive functions. As a result, ambidextrous people possess more intellectual capacities.
Therefore the reason left-handers are intelligent is because in a world which is geared towards right-handers, left-handers tend to become ambidextrous. Since they use all kinds of products and utilities made for right handers.
So the keyword is -- If you wish to be more intelligent you would have to remove the block for left and use both the hands.