Case Study 10.2: What Testosterone Actually Does

Case Study 10.2: What Testosterone Actually Does

The Mythology and the Science

Ask a random person on the street what testosterone does, and they will likely give you a confident answer: it makes men aggressive, sex-driven, competitive, and unfaithful. It is the biological explanation for manspreading, road rage, financial risk-taking, and infidelity. It is invoked by lawyers in criminal defense cases, by coaches justifying high-contact sport culture, by evolutionary psychologists explaining male mating strategies, and by men excusing their own behavior with a shrug: "Can't help it — testosterone."

This account is wrong. Not completely — testosterone does do things — but the popular model of testosterone as a master switch that mechanically produces male-typical behavior is a construction that the actual science does not support.

Cognitive neuroscientist Cordelia Fine has done the most thorough job of dismantling this mythology, first in Delusions of Gender (2010) and then in Testosterone Rex (2017). Fine is not a testosterone skeptic; she is a science communication skeptic. Her argument is that sloppy extrapolation from animal studies, overconfident interpretation of correlational data, and confirmation bias in popular reporting have combined to produce a narrative about testosterone that is far more certain — and far more deterministic — than the evidence warrants.

The Bidirectional Relationship

The most important single finding in testosterone research, for our purposes, is this: social context changes testosterone levels, and those changes then produce behavioral effects. The causation runs both ways.

Classic demonstrations of this bidirectionality come from sport. Men (and women) who win competitions show testosterone elevations; losers show decreases. This has been documented in tennis matches, chess games, and — in studies that are admittedly more ecologically odd — even watching one's favorite sports team win. The brain, responding to social success, upregulates testosterone, which then produces further effects on mood, confidence, and motivation.

The relationship is context-dependent in ways that matter. Testosterone correlates with aggression more strongly in low-status social environments than in high-status ones. It correlates with risk-taking more in financial contexts than in physical ones. It is associated with dominant behavior in competitive, zero-sum contexts but not in cooperative ones. The hormone does not produce behavior; it shifts thresholds and biases in systems that are already sensitive to social context.

A particularly striking finding comes from fatherhood research. In cultures where fathers take active caregiving roles, men's testosterone levels decline significantly after the birth of a child — sometimes by as much as 30 percent. This decline is associated with increased emotional responsiveness to infant cues and increased caregiving behavior. The biological system is not simply producing male dominance drives that culture must suppress; it is flexibly responding to social role in ways that facilitate cooperation and care.

The Attraction Question

For attraction research specifically, the testosterone story matters in several ways.

First, the relationship between testosterone and sexual desire is weaker than popular accounts suggest. Testosterone does play a role in sexual motivation — this is best documented in clinical contexts where testosterone is very low (due to medical conditions or treatments) and libido suffers. But within the normal range of variation, testosterone levels are a poor predictor of individual differences in sexual desire for either men or women. Many other factors — stress, relationship satisfaction, sleep, novelty, emotional connection — appear to be equally or more important.

Second, the popular claim that testosterone explains male desire for variety and female preference for selectivity has been substantially complicated by the research. Women's testosterone levels also rise in response to attractive potential partners. Women's self-reported sexual desire fluctuates with hormonal cycles in ways that are real but often smaller than popular accounts suggest, and that vary significantly across individuals. The hormone story is not a simple explanation for sex differences in desire.

Third, because testosterone levels respond to social context, they carry information about social experience — not just about fixed biological states. A person who grows up in an environment of chronic stress and low social status will show different average testosterone patterns than someone who grows up in secure, high-status conditions. This is not merely a statistical curiosity; it means that the hormone system is a record of social history, not just a biological given.

Fine's Critique and Its Limits

It is worth being clear about what Cordelia Fine's critique does and does not claim. She is not arguing that sex differences in behavior are entirely socially constructed, or that testosterone has no real effects. She is arguing that the popular version of the testosterone story — which portrays male-typical behaviors as mechanically inevitable outputs of a hormone — is empirically unwarranted and socially harmful.

The empirical problems include: heavy reliance on rodent studies that do not translate cleanly to humans; small-to-moderate effect sizes that are rarely reported honestly in popular accounts; failure to distinguish between average differences and individual variation; and circular reasoning (male-typical behavior in humans is measured, testosterone is present, testosterone is inferred to cause the behavior, with little attention to the social construction of "male-typical" in the first place).

The social harms are real too. A culture that tells men their testosterone makes them aggressive, unfaithful, and unable to control their sexual behavior is not merely offering a biological description. It is constructing an excuse structure that individuals can use to avoid accountability, and it is telling women that male behavior is a natural force to be managed rather than choices to be made.

Fine does not deny that biology matters. She denies that biology determines, in the simple, linear, culturally invariant way that testosterone mythology implies. Her alternative is not "everything is social construction" but rather "the biological and the social are intertwined in ways that resist simple causal stories."

Implications for Attraction Research

What the testosterone case teaches us is methodological as much as substantive. When we observe a correlation between a biological variable and an attraction behavior, we should ask:

Does the causation run from the biology to the behavior, from the behavior to the biology, or (most likely) both?
Does this correlation hold across different cultural contexts, or is it specific to environments with particular social norms?
What is the effect size, and how much of the variance does this biological variable explain relative to social and psychological variables?
Are we measuring the hormone, or are we measuring the conditions that typically produce that hormone level — and might those conditions directly explain the behavior without the hormone as mediator?

These are not unanswerable questions. They are the questions that good research asks, and that popular science too rarely reports.

Questions for Discussion

The finding that testosterone declines in new fathers in cultures where men take active caregiving roles is often cited as evidence against testosterone determinism. A critic might respond that this just shows culture can suppress biological drives. How would you evaluate this alternative interpretation? What evidence would help distinguish between the two accounts?
Think of a specific behavior that is commonly attributed to testosterone (e.g., aggression, infidelity, risk-taking). Using the bidirectional model developed in this case study, describe at least two social-contextual factors that likely moderate the relationship between testosterone and that behavior.
Cordelia Fine argues that testosterone mythology is socially harmful, not just scientifically inaccurate. Do you agree that the social stakes of hormone science are high enough to warrant the kind of critical scrutiny she applies? Or does this risk letting political concerns distort the science in a different direction?