Approximately 12% of the US population are left-handed – but standing out in a co-operative world can help some thrive
Athletes could help us understand why most people are right-handed (and that seems worth understanding today, on International Left-Handers Day).
In the United States, despite scientific agreement that its partly genetic, the rate of left-handedness has fluctuated over time. According to a 2009 paper titled the history and geography of human handedness, American left-handedness declined before 1900, then picked up again, reaching approximately 12% possibly because left-handedness is no longer corrected in schoolchildren.
To see why left-handers are still a minority, two mathematicians (both right-handed) analyzed athletes. Their study, published in 2012, hypothesized that the delicate balance between cooperation and competition has evolved humans towards our current rate of left-handedness. In a perfectly cooperative world, 100% of us would be righties, and in a perfectly competitive one, wed be equally split 50%-50%.
The academics turned that theory into a mathematical model which they tested on several sports. The model accurately predicted the percentage of left-handed elite athletes in baseball, boxing, hockey, fencing and table tennis. The more competitive the sport, the higher the share of left-handers (over 50% of top baseball players are left-handed): as the report says: physical competition, on the other hand, favors the unusual. In a fight, a left-hander in a right-handed world would have an advantage. Thats why only 4% of golfers – who compete in a sport where you are not physically interacting with others are left-handed.
So, whichever hand you rely on, you can rest assured you are contributing to the fine balance of human society as a whole.