Left or Right?

Dominant hands and social behavior.

The difference between right- and left-handedness has always been something of a puzzle. However, Daniel M. Abrams, PhD, and his graduate student, Mark J. Panaggio, believe a person’s dominant hand is related to social behavior.

“The more social the animal—where cooperation is highly valued—the more the general population will trend toward one side,” said Abrams. “The most important factor for an efficient society is a high degree of cooperation. In humans, this has resulted in a right-handed majority.”

If a society were entirely cooperative, everyone would be same-handed, but if competition were important, one would expect the population to be 50/50. Abrams and Panaggio studied data from competitive sports to see if social behavior is related to population-level handedness. Cooperation favors same-handedness for sharing tools, for example. Yet physical competition favors the unusual—hence why in some sports, left-handed athletes are highly valued.