The XX Factor

Women’s Testosterone Levels Rise Even When They Just Act Like They Have Power

High-intensity trading floors can cause testosterone surges;  shown here, a scene from August at the Chicago Board Options Exchange.

Photo by Scott Olson/Getty Images

In recent history, too-high testosterone levels have been used to disqualify women from women’s sporting events. The hormone traditionally associated with masculine traits has also been a lynchpin of evolutionary psychology, which likes to explain men’s behavior by pointing to their primal, hormonal needs for sex and supremacy.

But hormone levels aren’t born; they’re made. A study published today by researchers from the University of Michigan found that women who play-acted scenarios that gave them power over someone else showed an increase in testosterone production, proving that gendered socialization and cultural norms factor along with biological makeup when it comes to testosterone levels.

The study had 100 actors pretend to fire a lower-ranked employee—sometimes with traditionally masculine behaviors (such as using dominant body language) and sometimes with traditionally feminine behaviors (raising their voices at the ends of statements). A control group watched a travel documentary. In both firing scenarios, the female actors experienced a boost in testosterone levels compared to the control group, leading the study’s authors to posit that the simple act of holding power is a testosterone trigger, with or without masculine performance.

Male test subjects didn’t show much of a change in their testosterone levels. The study’s authors suggest that this might be a result of their greater past participation in competitive activities or situations that require them to wield power, which would diminish their testosterone response.

This is just the latest of several pieces of research that explore why and how hormone levels—one of the most cited biological markers of sex—are mutable. When men become fathers, for instance, their testosterone levels drop more than twice as much over a four-year period as their childless peers. Among fathers who spent three or more hours a day on childcare, the drop is even more drastic. The high-risk behavior of male Wall Street traders causes testosterone surges that compound in the competition crucible of the trading-room floor, leading to even riskier decisions and more bursts of testosterone. (Hanna Rosin has brilliantly compared this phenomenon to the mystical synchronizing of women’s periods.)

It’s a classic chicken-and-egg dilemma: Do women hold proportionally fewer positions of power because mighty, manly, testosterone-loaded men are manlier and mightier? Or do men have more testosterone because gender-based discrimination and stringent socialization have funneled women into less competitive, less powerful positions? This study suggests that, when it comes to discussing gendered bodies, the nurture factor might be just as relevant as nature.