Chimpanzees (Pan troglodytes ) Are Predominantly Right-Handed: Replication in Three Populations of Apes

Population-level right-handedness has historically been considered a hallmark of human evolution. Even though recent studies in chimpanzees ( Pan troglodytes ) have demonstrated population-level right-handedness for certain behaviors, some have questioned the validity and consistency of these findings by arguing that reported laterality effects are specific to certain colonies of apes and to those chimpanzees reared by humans. The authors report evidence of population-level right-handedness in 3 separate colonies of chimpanzees. Moreover, handedness in the 3 colonies was unrelated to the proportion of subjects that were raised by humans. This is the strongest evidence to date that population-level handedness is evident in chimpanzees and is not an artifact of human rearing.