Being “left-handed” is much more than writing or throwing a baseball with your left hand. Even our amino acids and DNA are affected by the dominant side of our body. On average, nine out of every 10 humans are right-hand dominant, so why are the remaining 10 percent of mankind left to deal with ink smudges from writing with their left hand and a tricky situation when it comes to driving a manual car? It may start at the source of our body’s inner workings: the brain. Since our brains are “cross-wired,” our right hand is controlled by the left side of our brain and our left hand is controlled by the right side of our brain. Evidence has suggested that during human evolution, a certain gene mutation caused our brain’s functions to specialize on one side. People with language and hand dominance in the left hemisphere of their brain are said to have two copies of the “Right Shift mutation.” Having one copy of this mutation causes less of a shift, and no copy of this mutation causes the shift to go either way by chance. So left-handedness could actually be caused by the lack of a gene. Research has also shown that right- and left-handedness could be a matter of genetics. For example, two right-handed parents have a nine percent chance of having a left-handed child, one left-handed parent and one right-handed parent have a 19 percent chance of having a left-handed child, and two left-handed parents have a 26 percent chance of having a left-handed child. Yet another theory suggests a brain shift for coordination starts in our prenatal development or even as far back as the primate phase of human evolution. So what does all this conflicting research surrounding why so few people are left-handed ultimately mean? We really don’t know the true answer, but maybe this video will clear up some of the mystery. source
