Don't Mess With Me, I'm Left-Handed!
Apparently, there is a high correlation between lefthandedness and violence. From The Economist:
By trawling the literature, checking with police departments, and even going out into the field and asking people, the two researchers [Drs. Charlotte Faurie and Michel Raymond] found that the proportion of left-handers in a traditional society is, indeed, correlated with its homicide rate. One of the highest proportions of left-handers, for example, was found among the Yanomamo of South America. Raiding and warfare are central to Yanomamo culture. The murder rate is 4 per 1,000 inhabitants per year (compared with, for example, 0.068 in New York). And, according to Dr Faurie and Dr Raymond, 22.6% of Yanomamo are left-handed. In contrast, Dioula-speaking people of Burkina Faso in West Africa are virtual pacifists. There are only 0.013 murders per 1,000 inhabitants among them and only 3.4% of the population is left-handed.
While there is no suggestion that left-handed people are more violent than the right-handed, it looks as though they are more successfully violent.
As the article points out, this high correlation doesn't work well in highly-developed societies because technology in combat (i.e. using guns) largely removes the left-hander's advantage. You can read more about it here.
