LEFT-HANDEDNESS AND LIFE-SPAN - A REPLY

L. G. Harris's (1993) critique of our hypothesis that left-handedness is associated with a shorter life span (S. Coren & D. F. Halpern, 1991 ) ignores the supporting statistical evidence, which virtually always shows an increased incidence of left handedness (or other left-sided l aterality) associated with a wide range of health risk factors, includ ing serious accidents, immune disorders, early onset breast cancer, al coholism, smoking, some types of mental retardation, homosexuality, bi rth-related complications (e.g., resuscitation at birth, extremely low birth weight, Rh incompatibilities, multiple birth, breech birth, and older maternal age), and selected categories of mental disorders. Giv en that there are no known risk factors that are elevated in right-han ded populations, the longevity hypothesis remains supported. L. G. Har ris's arguments against our hypothesis are based on studies that show nonsignificant results, which can be explained by these studies' low s tatistical power.