Left-handedness and intelligence
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 centres of the brain.
McManus also says that the increase in the 20th century of people identifying as left-handed 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 for 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.