It is time to answer the sixth and final question in my series Six Questions Left-handers Ask.
- I write with my left hand but do other things with my right hand. Is that normal?
- Everyone in my family is right-handed but me. Why? I thought handedness is genetic.
- Is it true that left-handers don’t live as long as right-handers?
- Are left-handers smarter and more creative than right-handers?
- If I try to switch writing from my left to my right hand, will I mess up my brain?
- Are left-handers better at sports than right-handers?
The study of a left-hander advantage in sports is connected to a theory of handedness called the fighting hypothesis. The fighting hypothesis addresses the puzzling question of why there is a persistent minority of left-handers existing among human populations for millennia. Left-handedness must bestow a fitness advantage to individuals otherwise the small numbers with this trait would have died out and disappeared thousands of years ago. The genetic idea of negative frequency dependent selection forms the basis of the fighting hypothesis. There is an evolutionary consensus that the fittest among us survive. The idea of negative frequency dependent selection maintains that the fitness advantage of a trait like left-handedness increases as the number of individuals in a population with this trait decreases. When our human ancestors faced each other in hand-to-hand combat, left-handers had the fighting advantage because right-handers had little experience fighting against them. This surprise effect led to a survival advantage for left-handers in these battle situations. The surprise effect and its survival benefit maintained a stable minority of left-handers in human populations across millennia of evolution. If the numbers of left-handers increased, the surprise factor and survival advantage would disappear as right-handers gained more experience fighting against left-handers.
Modern warfare no longer depends on hand-to-hand combat. However, one test of the fighting hypothesis can be found by examining the handedness of athletes in interactive sports that involve close personal contact such as boxing and various martial arts. The handedness of athletes participating in these sports can be compared to those in sports that are non-interactive in terms of personal contact such as rowing, diving and skiing. The fighting hypothesis contends that more left-handers will be found in the interactive sports where the surprise element gives them a competitive advantage. Consistent with the predictions of the fighting hypothesis there are twice as many left-handers participating in direct interactive sports when compared to those participating in the non-interactive sports…21% versus 10% respectively. Unfortunately, the data do not support the second prediction from the fighting hypothesis. Left-handers do not win more frequently when competing against right-handers in combat sports like boxing and mixed martial arts. There is no win advantage to the left-handed punch shown in this photo.
People often point to the number of elite left-handed tennis players as an example of a left-hander advantage in a sport. Tennis is an indirect interactive sport where an athlete competes against an opponent but does not physically touch the other person during the match. Researchers have concluded that a left-hander advantage in tennis is based on the right bias in the sport rather than an inherent left-hander talent for playing tennis. Both right- and left-handed tennis players tend to serve the ball to the right side of the opponent’s court. This places the ball in a forehand stroke position for a left-handed player but in a backhand stroke position for a right-handed player. The forehand stroke is thought to be the stronger of the two, giving left-handers a stroke advantage in returning the ball across the net. There is an over-representation of left-handers only among the elite group of players. Players with lower rankings show the same rates of left-handedness as found in the general population. It could be that elite tennis players become aware of this rightward bias after years of competing against right-handers. This awareness contributes to their advantage, their win record, and eventually to their upward movement in the world rankings of tennis players.