Testosterone: An Unauthorized Biography

Abstract

Among all the endogenous small molecules of our bodies, perhaps oxytocin and testosterone have garnered the most mystique, the supposed biochemical mediators of love and dominance, respectively.In the popular imagination, we know what these molecules do. But biology isn’t simple. A single compound can have myriad effects throughout a body—depending on the relative concentrations of receptors in different organ systems, the same molecule might affect two people’s bodies very differently.Testosterone unpacks dozens of studies on the role of testosterone in athleticism, psychology, and sexuality, attempting to separate the robust, significant findings from a swirl of hyperbolic summaries and news reports. (While reviewing the book, we chanced across conspiracy-theory-ish headlines bemoaning a drop in testosterone levels among young men, others touting testosterone as an anti-aging miracle drug. This sort of hype isn’t new: throughout the 1920s, celebrity doctor John Brinkley toured the country implanting goat testicles into the bodies of credulous patients as a cure for diminished vigor.)Testosterone is a potent molecule; high doses of exogenous testosterone can permanently change a person’s voice, face shape, distribution of body hair, and ability to build muscle mass, especially if that person was assigned female at birth. But numerous correlation studies also attribute personality traits to small differences in the interpersonal levels of endogenous testosterone, often in ways that are unintentionally classist or racist; for instance, dominance-seeking behavior is described as antisocial aggression when studied in prison populations and as prosocial leadership when studied in university settings. Jordan-Young and Karkazis deftly note these hidden biases in scientific research.Often, Jordan-Young and Karkazis are frustrated by the narrow scope of questions that have even been asked, reminding us of the book Invisible Women, in which Caroline Criado Perez explains how the paucity of data collected on the ways that medicines, buildings, and political structures affect women has perpetuated designs that actively harm women.The same gender-biased omissions in data collection appear throughout the scientific literature on testosterone. The design of our experiments determines the range of possible knowledge that we might gain from them; for instance, perhaps because we refer to testosterone as a “male sex hormone,” researchers have only recently begun to study the role of testosterone in ovulation and female fertility.At times, though, we felt that Jordan-Young and Karkazis were overly critical of studies they cited. In our experience attending journal clubs, undergraduates often seemed most trusting of research papers’ discussion and conclusion sections; midcareer graduate students, hypersensitive to imperfect data or overstatement; and postdocs and faculty, more understanding of the compromises inherent in any scientific study. Most scientists would conduct experiments differently if all the results could be predicted in advance, or if they were granted an infinite budget of time and money. (Memorably, at one of Kirstin’s first graduate journal clubs, the faculty advisor listened patiently for five minutes while the students denigrated the stray bands of a paper’s Western blot. Finally, the professor smiled and said, “You, too, will have such bands.”)Not that we’d wish for Jordan-Young and Karkazis to overlook the flaws of ill-designed studies, but they don’t always exhibit the sympathy that comes from undergoing one’s own trials and tribulations in the laboratory. And while we enjoyed the book, the stylistic conventions and jargon from gender theory might reduce its appeal to students and teachers of science. We found ourselves wishing it was written more accessibly, because the study of testosterone is fascinating: implicated in wound-healing, essential for gender-affirming medical care, interwoven with many men’s self-conceptions of masculinity, stubbornly debated in the context of competitive sports. While Jordan-Young and Karkazis don’t offer firm conclusions, their careful guidance and philosophical insights could help anyone think about and teach these subjects from a more nuanced, open-minded perspective.