Is “reductionism” in behavioral genetics a boon or curse?


Breaking a watch into its components to study how they work independently and together is a perfectly acceptable method of understanding watches. No one who would claim “a screw is involved in the keeping of time” would be accused of reductionism.

Yet reductionism—which wasn’t always and isn’t necessarily—a bad word, haunts modern science, and genetics in particular. It has come, largely, to connote a myopic approach that misses the complexities and nuance of the whole in its focus on individual components. In other words, studying the trees and ignoring the forest.

The invocation of genetic reductionism is often used as a rhetorical club to hammer home the fact that genes are modulated by other genes and by the environment. As applied to human sexuality, it can be a curse; as applied to modern research into mental health it may be a blessing. This is arguably an issue of perception, and it’s not exclusively divided between “Public” and “Science.”

Let’s look at the two examples. A “gay gene” backlash emerged from the American Association for the Advancement of Science (AAAS) annual meeting in February, and I wrote about it for Gene-ius. A post from the Wiring The Brain blog by neurogeneticist Kevin Mitchell sums up the reaction:

Reductionism! Single genes can’t cause complex traits – it’s patent nonsense to say that they can! Biological organisms are complex systems interacting in complex ways in an ever-changing environment – particular behaviours can’t be simply determined by genes.

My reaction, in line with Mitchell’s, was to point out that no one, least of all the authors of the “gay gene” study, claim that a single gene can explain all of homosexuality. This form of reductionism present in the study is an acceptable and necessary step in developing a full understanding of human behaviour; it’s taking apart the watch. Whereas geneticists studying sexuality are met with anger at what is perceived as an excessively reductionist approach, the mental health research establishment has been shaken up lately by people pointing out what is essentially a lack of reductionism in the discipline.

The mental health “bible,” the D.S.M. (Diagnostic and Statistical Manual of Mental Disorders), was grilled for a distressing “lack of validity”. The practice of treating mental illness, for all the headlines pointing out new genes associated with some disorder or another, has remained largely a macro-level, behavioral affair. Indeed, as the New York Times has pointed out, the genetics- and neuroscience-oriented overhaul of the National Institute of Mental Health by its newest director, Thomas R. Insel, has ruffled more than a few feathers. He has taken what was an almost purely behavioral endeavor and sharply shifted the focus to biological brass-tacks in an attempt to get at the fundamental underlying causes of mental illness. Not everyone thinks the answer can be found in genetics and neuroscience, though:

“Instead of being an institute of mental health, he has made it almost exclusively a brain research institute,” Dr. Allen Frances, an emeritus professor of psychiatry at Duke and the author of the book “Saving Normal,” wrote in an email. “N.I.M.H. is betting the house on the long shot that neuroscience will come up with answers to help people with serious mental illness.” He added, “It does little or no psychosocial or health services research that might relieve the current suffering of patients.”

Might a fear of reductionism-as-myopic be in part behind the reactions of those who oppose Insel’s changes? As a young science writer, I am sensitive to the perceived tide of reductionism in biology. It affects all of us, in science and in journalism. Even the GLP carries headlines that reflect a sensitivity—perhaps an exaggerated one—to concerns about reductionism; just recently we changed a ScienceDaily headline from “Scientists identify gene linking brain structure to intelligence” to “IQ gene? Uh-oh, scientists believe they have found one.”

Mitchell cuts through this Gordian knot with a simple, obvious-in-hindsight distinction: There is a difference between methodological reductionism, a tool, and philosophical reductionism, a guiding principle. Gay gene studies, Insel’s changes to the NIMH: both are using a reductionist method—modern genetics—in a quest for understanding. It’s all too easy to perceive methodology as philosophy. As a philosophy, it does indeed risk missing the forest for the trees. We can appreciate the precise, ordered beauty of a watch (or the staggering spectrum of human behavior) in action while still taking it apart to better understand the whole.

Kenrick Vezina is the Gene-ius editor for the Genetic Literacy Project and a freelance science writer, educator, and amateur naturalist based in the Greater Boston area.

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