August 13 is designated International Lefthanders Day. It was first observed on the 13th of August 1976. As its name suggests, it is meant to promote awareness of the inconveniences facing left-handers in a predominantly right-handed world. It celebrates the uniqueness and difference of those who are form seven to ten percent of the world's population. People who are left handed use their right brain, which appears to give them an edge in geometry and related subjects. There also appears to be a connection between left-handedness and intelligence, some studies show. In his book Right-Hand, Left-Hand, Chris McManus of University College, London argues that the proportion of left-handers is rising and left-handed people as a group have historically produced an above-average quota of high achievers. He says that left-handers' brains are structured differently in a way that widens their range of abilities and the genes that determine left-handedness also govern development of the language centers of the brain. McManus also says that the increase of people identifying as left-handed in the 20th century could produce a corresponding intellectual advance and a leap in the number of mathematical, sporting, or artistic geniuses. In 2006, researchers at Lafayette College and Johns Hopkins University in a study found that left-handed men are 15 percent richer than right-handed men among those who attended college, and 26 percent richer if they graduated. The wage difference is still unexplainable and does not appear to apply to women. In 1998, a study suggested that approximately 7 to 10 percent of the adult population was left-handed. Studies indicate that left-handedness is more common in males than females. :slap: