在这个右撇子占绝对多数的世界，却有这样一群左撇子：他们之中天才辈出，他们对人类文明的贡献和对人类历史、生活的影响远远高于他们在人口中的比例。左撇子到底缘何而来？我们来看看科学家的解释。 

    "Because lefties do it right!" 

    "Because left handed people are the only people in their right minds?" 

    This question is definitely not a no-brainer. 

    Two theories predominate in the debates that rage on as to why a mere 4% of the population is left-handed. Most authorities agree, to the relief of many a mother of a left-handed child, that if the child prefers using the left hand, and functions well with it, there is no need to correct this "condition." 

    One theory centers on the two halves of the brain, i.e. the left half and the right half, each of which functions differently. Medical science believes that the left half of the brain predominates over the right half. The stem of this theory is the fact that nerves from the brain cross over at neck-level to the opposite side of the body, and nerves from the other side of the brain reciprocate. The end result is that the opposite sides of the body are supplied by the opposite sides of the brain. 

    The predominant left half of the brain, which graciously supplies the right half of the body, theoretically renders it more skillful in reading, writing, speaking, and working, and makes most people right-handed. "Lefties," however, are the product of an inversion, whereas the right half of the brain predominates, and they work best with the left side of their bodies. 

    Theory number two trickles down to the asymmetrical nature of the body. Examples of the asymmetry, which flows from head to toe, are that the right side of our faces differs slightly from the left, that our legs differ in strength, or that our feet vary in size. One aspect of this asymmetry is that for most people the right hand is stronger than the left. 

    There is no doubt that all exist in a "right-handed society," which manufactures most basics, including scissors, doorknobs, locks, screwdrivers, automobiles, buttons on clothing, and musical instruments for the 96%. Left-handed people compensate for this snobbery of sorts, by being members of an elite society, which includes many of the greatest geniuses, including Michelangelo, Leonardo da Vinci, and The Useless-Infomaster.

    reciprocate: 交叉，交互