Lateral preferences are strange, puzzling, and on the surface, not particularly adaptive aspects of behavior. Why one chooses habitually to write or to brush the teeth with the right hand, while a friend or family member habitually uses the left hand, might be interesting enough to elicit some conversation over dinner or a drink, but certainly does not seem to warrant serious scientific study. Yet when one looks at human behaviors more carefully, one becomes aware that asymmet rical behaviors favoring one side or the other are actually a fairly universal characteristic of human beings. In the...