ABSTRACT
Contemporary estimates of righthandedness in adults range from 70% to 90% depending on cultural background and the criteria used to determine the preferred hand (Porac & Coren, 1981). In Western countries, values range from 85% to 95% (Brackenbridge, 1981). These figures raise two general questions: why do the majority of humans show a righthand preference and much less than half of any population a lefthanded one? In turn, we can ask whether a population bias for the right hand is unique to humans and if a lefthand preference constitutes a pathological deviation from the dextral norm. These questions seem to touch on the very essence of what it is to be human. As a consequence, they sometimes elicit strong emotional reactions. One of us, a lefthander forcibly converted in childhood to using the right hand for writing and other tasks, can attest to this fact.
