About 8 to 15% of the world population are left-handed. Historically, left-handedness has been associated with evil, immorality, and wrong doing. However, lefties have achieved great success throughout history. Five of the last seven Presidents of the United Sates are left-handed: Gerald Ford, Ronald Reagan, George H.W. Bush, Bill Clinton, and Barack Obama. Other great leaders, such as Julius Caesar, Alexander The Great, Napoleon Bonaparte, King George VI, Simon Bolivar, Queen Victoria, Mahatma Gandhi, and Otto von Bismarck were left handed.
Charlotte Faurie and Michel Raymond of the University of Montpellier in France reported in the journal Proceedings of the Royal Society B (DOI: 10.1098/rspb/2004/2926) their examination of the number of left-handed people in unindustrialized cultures as well as the homicide levels within each culture. They discovered a correlation between levels of violence and the proportion of the left-handed population—the more violent a culture, the higher the relative proportion of left-handers.
Left-handed people have been found to be more prone to some health problems, suggesting the trait ought to disappear naturally over many generations through natural selection. However, left-handers continue to make up a small proportion of the human population, hinting there could also be some evolutionary advantage to being left-handed. In addition, the ratio of left-handers to right-handers is higher in successful sportspeople than it is in the general population, suggesting there is an advantage to being left-handed. The researchers hypothesized that, because of the advantage in sports, there could be a similar advantage in fights; the theory being that right-handed competitors are less accustomed to facing left-handers.
Faurie and Raymond studied several unindustrialized societies that had varying rates of homicide, using their own fieldwork and ethnographic literature. They excluded industrialized cultures since they tend to have more firearms and the use of firearms is unaffected by handedness.
At the lower extreme of their samples was the Dioula of Burkina Faso in which just 3.4% of the population is left-handed and only 0.013 murders are committed per 1000 people each year. At the upper extreme was the Eipo of Indonesia in which 27% of the population is left-handed and the homicide rate is three murders per 1000 people each year. The strong correlation between the proportion of left-handers and the number of homicides in each culture suggests that left-handers are more likely to survive a fight.
Since right-handed fighters train with mostly right-handed opponents. they have less experience fighting lefties. However, lefties also train with mostly right-handed opponents. This gives lefties a bit of an edge in the ring.