Chapter 12 - Leftovers

Abstract

Individuals show consistent patterns of hand clasping, arm folding, and leg crossing. When the two hands are clasped with the fingers interlaced, the thumb on one hand is consistently placed over the thumb on the other hand. The same is true when a person folds his or her arms over the chest. One forearm is placed consistently over the other forearm. When seated, people also prefer to cross one leg over the other. These lateral preferences are consistent and individuals are uncomfortable when forced to adopt the nonhabitual position. Hand clasping, arm folding, and leg crossing side preferences may be related to the side of handedness, they are not related to each other. Both right- and left-handers prefer the left top thumb and left arm position for hand clasping and arm folding. Right-handers prefer the right leg on top when crossing the legs while left-handers do not show a preference for either leg. A final consideration concerns the evolution of handedness. Great apes (chimpanzees, bonobos, orangutans, and gorillas) are close evolutionary cousins of humans. These primates show handedness at an individual level and chimpanzees also display a right-sided bias at the population level. A theory that connects the evolution of handedness in humans and great apes claims that the common adaptation that promoted the bias toward right-handedness in both groups was the development of movement skill required for tool use.