The baseline for the population’s percentage of left-handed people is around 10 percent, but in some societies that number is far greater. Among Venezuela’s Yanomami tribe, about 5 in every 1,000 people are murdered yearly—and about 23 percent of the population is left-handed. For the Eipo in Indonesia, the murder rate is 3 in 1,000, and they’re about 27 percent left-handed. And then there are the people of Jimi Valley in Papua New Guinea, who have a murder rate of 5.4 in 1,000 and an above-average instance of left-handed people at 13 percent.