This is an article from the spring 2016 issue of LSA Magazine. Read more stories from the magazine.

It has long been understood that hormones have a powerful influence on our behavior. New research suggests our behavior can actually influence our hormones too.

The gender stereotypes that define the way we expect men and women to behave have blurred in the last 50 years, but many of the basics have stayed the same. Women are generally considered to be nurturing, intuitive, and more submissive. Men tend to be seen as competitive, in charge, and good at math. For a long time we believed that gender—the specific ways that cultures encourage each sex to behave—had a biological basis, namely hormones. Sari van Anders, an associate professor of psychology and women’s studies, found herself thinking about the ways we assume hormones induce gendered behavior and then wondered: What if it’s gender that affects hormones instead?

As a social neuroendocrinologist, van Anders has made her career from such questions, many of which she investigates in her lab. The lab’s research is broad, and its subjects are complicated. Some examples: sexuality, sexual diversity, and the relationship between gender and sex. The lab also investigates hormones from within a social context, including a recent study about the king of hormones: testosterone.

Acting Bossy

We usually associate testosterone with men, and for good reason: We all produce testosterone, but men produce three to six times more than women. One study from van Anders’s lab suggests power might partly explain why men have higher testosterone.

The study participants, all trained actors, were directed—in an interdisciplinary collaboration with Jeffrey Steiger, then at U-M’s Center for Research on Learning and Teaching—to pretend to sack a subordinate in a stereotypically feminine way one day and a stereotypically masculine way the next. In both scenarios, when men fired the employee, their testosterone climbed by three or four percent. When women did the same, their testosterone spiked by a surprising 10 percent.

The study suggests that it’s simply wielding power that increases a person’s testosterone, whether it’s exerted in a stereotypically male or female way. It’s an early finding, but it raises a classic chicken-and-egg scenario: Does living in a culture that discourages women from acting powerful explain (in part) their lower levels of testosterone, or does men’s higher testosterone encourage them to behave in ways that make them more powerful, as is more typically assumed?

“We usually think of gender as something on the body, like clothes. But our research shows gender can actually get into our cells and our brains and change them,” explains van Anders. “I’m really interested in how gender gets into the body.

“I see the contribution—or the interruption—my work creates when people hear about these things, people who never thought sex and gender were different, or who never thought about testosterone as more than a number that a doctor might measure,” van Anders says. “This shift is happening among scientists and the medical community and in the general public, too.

“Most people don’t know the difference between gender and sex, and trying to convince them that gender affects sex is many steps beyond. I’m trying to just introduce these ideas, and I’m hoping people can make the leap.”