Science and the History of Left-Handedness Howard Kushner tells us how history is essential to understanding the substance of science.

On the Other Hand: Left Hand, Right Brain, Mental Disorder, and History

By Howard Kushner (2017, Johns Hopkins University Press) 216 pages with notes, index, and photographs

What is history good for? It is a particularly vexing question for historians of science, who have long grappled with the mismatch between their methodology and that of the disciplines they study. Does history merely provide ornamentation to scientific truth, an anecdote or two to lighten up a lecture, or at best a narrative that can confirm the identity of practitioners and add social glue to the profession? Or can it touch the substance of scientific work and contribute in meaningful ways to scientific understanding? Throughout his long and distinguished career, Howard Kushner has sought to demonstrate the truth of this latter position. In his work on the histories of Tourette’s syndrome (a debilitating neurological condition that causes uncontrollable behavior including motor tics and cursing) and American suicide, he has shown how history can assist the medical sciences in their work, by probing claims to medical knowledge, working out the role of cultural forces in shaping the scientific enterprise, and reconstructing the lived experience of suffering.[1]

In comparison to this previous work, Kushner’s new book on left-handedness might appear a shift in approach and tone. Unlike suicide or Tourette’s, in 21st-century America, left-handedness does not strike one as a serious stigma, nor the site of palpable social injustice. Nevertheless, On the Other Hand is best seen as a continuation of Kushner’s previous work. Kushner argues that prejudice against left-handedness has caused real harm and conversely that the “toleration of left-handedness serves as a barometer of wider cultural toleration and permissiveness” (xiii). Moreover, Kushner’s new book is the culmination of a lifetime’s project of demonstrating the importance of history in disability studies. Here Kushner addresses scientific researchers directly, and seeks to show why historical context and expertise matters.

Kushner argues that prejudice against left-handedness has caused real harm and conversely that the “toleration of left-handedness serves as a barometer of wider cultural toleration and permissiveness.”

The science of left-handedness is peculiarly susceptible to a historical approach.

To start with, left-handedness is a highly variable phenomenon, with an astonishing range of prevalence today. Depending on the geographic location, left-handers constitute between 0.06 and 25 percent of the overall population (the lowest rates can be found in China, Taiwan, and parts of Africa, and the highest rates in North America and Western Europe). Kushner begins to unpack these numbers by analyzing a variety of factors, from different attitudes towards re-training to the definition of handedness: if people use their right hand for eating and writing but the left hand for all other activities, are they right-handed or left-handed? Difficult to define and highly responsive to social pressure, left-handedness is not an unproblematic scientific object.

At the same time, left-handedness has been burdened with a range of often-negative social meanings. As Kushner observes, “the left hand has served as a proxy to justify or authorize beliefs and interventions, such as segregating the sacred from the profane; identifying and categorizing mental illness; [and] justifying racist and sexist beliefs” (132). In addition, left-handedness has been associated variously with learning disabilities, mental illness, criminality, femininity, Jewishness, and talent and creativity, amongst others.

Kushner shows how many of these prejudices live on, even though they are now “clothed in the methods and conclusions of current science” (137). The new garb, Kushner argues, is not a guarantee of scientific accuracy, and he draws attention to the subtle shifts and elisions that are used to justify these conclusions. In his discussion of the association between left-handedness and homosexuality, Kushner argues convincingly how the connection only becomes visible if one uses a “problematic and nonspecific category of non-right-handedness” (136). There is simply no correlation between homosexuality and left-handedness as normally defined. Similar argumentative moves lie behind correlations between left-handedness and autism and schizophrenia. At other times, arguments rely on outmoded science, for instance in the “myth” (xi) that left-handedness is associated with talent and creativity. This claim is based on the (false) assumption of switched hemispheric dominance for left-handers, and the belief that the right hemisphere is the seat of creativity.

The seepage of social prejudice into scientific research has a long history. Since the late 19th century, Kushner shows, left-handedness has been tied into politically loaded debates over the relative importance of nature and nurture. The clash between the Italian criminologist Cesare Lombroso (1835-1909) and the French anthropologist Robert Hertz (1881-1915) is a case in point. Taking left-handedness to be a sign of criminality, insanity and mental retardation, Lombroso figured it as a physical manifestation of atavism, displaying traits of an earlier, and more primitive, developmental stage. Lombroso understood left-handedness in biological and determinist terms. In contrast, Hertz associated left-handedness with talent and creativity, an argument which led him to foreground social pressures. He argued that if one overcame the age-old “stigma attached to left-handedness,” one would be able to “unleash long-suppressed creative potentials” (17). For Kushner, this history lives on. Debates are still organized by the same dichotomy of biology and culture. He recounts the appeal of population studies and environmentalist accounts like the “GBG hypothesis” (named after its proponents, Norman Geschwind, Peter Behan, and Albert Galaburda) in the 1980s where left-handedness (alongside learning disabilities, immune disorders, and talent) was interpreted as an “association disorder” resulting from environmental damage in utero (95). These views, which never became mainstream, were displaced in the 1990s with the rise of molecular genetics, a paradigm that is still dominant. The way the science of left-handedness has ricocheted between different versions of these two positions allows Kushner to place current genetic assumptions under scrutiny. Monocausal explanations for left-handedness are only momentarily convincing. He argues that both cultural and biological models, if totalizing, are most likely the product of ideology. In order to provide longer-lasting solutions to the “mysteries of handedness,” one has to embrace the complexity and “multifactorial etiology”(154) of the phenomenon.

Since the late 19th century, Kushner shows, left-handedness has been tied into politically loaded debates over the relative importance of nature and nurture.

Kushner deploys his historical research in another way. By tracing the development of individual cases over the long haul, he is able to introduce factors to which most scientific studies, subject to publication pressures and the consequently short timelines, are blind. Drawing on a series of touching case histories recorded in the 1930s, Kushner reveals the effects of retraining, how the forced changing of the dominant hand resulted in the “tying of tongues,” and how the stuttering was often reversed by a subsequent return to the dominant hand. Placing scientific studies back into the context of the lives they affect allows Kushner to humanize work that can often lose sight of the individual.

So what is history good for? If we read On the Other Hand as a meditation on the uses of history, we might say that for Kushner, history itself emerges as a left-handed discipline. History does not engage directly in the main task; it is not science and does not perform experiments or long-term studies itself. But as Kushner shows it is important for this kind of work nevertheless, approaching scientific knowledge from another angle; it is a steadying hand that helps orient and support the other, right-handed, disciplines. In Kushner’s capable hands, the past emerges as a crucial auxiliary for scientific work today.

[1] A Cursing Brain? The Histories of Tourette Syndrome (Cambridge, MA: Harvard University Press, 1999) and Self-Destruction in the Promised Land: A Psychocultural Biology of American Suicide (New Brunswick, NJ: Rutgers University Press, 1989).