- On the Other Hand: Left Brain, Right Brain, Mental Disorder, and History by Howard I. Kushner
Handedness, Genetics, Psychology, Biology
On the Other Hand is an insightful, engaging book convincingly argued, and one in which the author admirably covers all the topics that are spelled out in his subtitle. He has been thinking about the subject of left-handedness nearly his whole life (as a left-hander), and now has brought to this circumstance his deft learning and considerable scholarship.
Kushner elucidates in the preface (p. xiii) three themes that underlie his book: the significance of disabilities and abnormalities throughout history; the repercussions of forced hand switching; and, the extent of the toleration of diversity in all societies and cultures. What intrigued me the most about On the Other Hand is that while it is easily understandable that in closed, deeply traditional societies "difference" might be interpreted as "bad," the assumption that being left-handed must be a sign of pathology—somewhere, somehow—still pervades even the most sophisticated and recent scientific work about the cause and significances of being left-handed.
Kushner builds the book around a conceit to which he keeps returning: the ideological contentions of two turn-of-the-century thinkers: the famous Italian criminologist and biological determinist, Cesare Lombroso (1835-1909), and the less well-known French anthropologist and cultural determinist, Robert Hertz (1881-1915). In a 1903 article, Lombroso asserted a biological connection between criminality, other "atavistic" traits, and left-handedness. Hertz, in response, in 1909, focused on the environment and declared that "right" had been traditionally linked to the sacred and "left" to the profane, the right linked to masculinity and strength and the left to femininity and weakness; hence the historical prejudice against left-handedness.
Kushner keeps reminding his audience of this conflict, whether it should be nature or nurture, biology or the social environment, that is applicable to the existence of left-handedness. As he pursues the history of twentieth and twenty-first century scientific studies, he compellingly demonstrates that for over a century the science of [End Page 350] handedness still revolves around these competing dualisms. Kushner emphasizes the faddish and incomplete nature of such scientific work over the past century, and argues that twenty-first century studies which emphasize genetics are just "the latest entries in a long … debate whether handedness is inherited or learned, and whether left-handedness is associated with learning disabilities" (p. 8). Kushner explores this rich history in detail and with intelligent critique. Two things are clear: one is that while there may be a connection between dominant (left cerebral hemisphere) lateralization and certain human characteristics, one of these traits is not handedness; handedness is not linked to brain laterality. The second is that almost all studies or conclusions still posit some kind of negative connection to being left-handed.
Although there is no room to report on most individual studies, I cannot resist the temptation of calling attention to the life and achievements of the brilliant "behavioral neurologist" Norman Geschwind (1926-1984), who hypothesized in the early 1980s that "learning disabilities, allergies, immune disorders, talent, and left-handedness" (p. 93) resulted from uterine trauma. This theory has faded and has even been renounced by one of its original formulators. But I will never forget my introduction to the manifold interests of the remarkable Dr. Geschwind. One of the delights of this book is that readers can become acquainted with scientists and psychologists of exceptional abilities about whom they might never have heard. On the Other Hand also offers engrossing scholarly potpourri throughout that add to the book's appeal. For example, we learn that both Lombroso and Hertz were Jewish, and that their theories regarding left-handedness were affected by the anti-Semitism they endured. Even the Dreyfus case played a role. Hertz was at the Ecole Nórmale Supérieure, hoping for a career as a politician, but when the conviction of Captain Dreyfus stirred up latent anti-Semitism in France, Hertz abandoned his political...