Violence and left-handers

Many people like to believe that at one time the human species was peaceful and has only become violent in recent times. New research shows that the continued presence of left-handed people indicates that violence played an important role in human evolution:

The endurance of left-handedness has puzzled researchers, because it is linked to disadvantages including an increased risk of some diseases.

But University of Montpellier experts, writing in Proceedings B, say it could be because they do well in combat.

The team saw that left-handers had the advantage in sports such as fencing, tennis and baseball.

They said that Western interactive sports such as these can be classed as "special cases of fights - with strict rules, including the "prohibition of killing and intentionally wounding the opponent".

This led them to speculate the same advantage may persist in more aggressive contexts, such as war, so societies which are more violent would have a higher frequency of left-handers.

The researchers analysed data for eight traditional societies; the Kreyol people of Dominica, the Ntimu of Cameroon, the Dioula-speaking people of Burkina Faso, the Baka of Gabon, Inuit people and the Eipo people of Irian Jaya, New Guinea.

They looked at homicide-rates and the frequency of left-handedness, and found they appeared to be linked.

The Dioula were found to have a homicide rate equivalent of one hundredth of a death per 1,000 people per year, and a left-handedness rate of just 3%.

But the Eipo had around three homicides per 1,000 people and a left-handedness rate of 20%.