Five myths about testosterone

Testosterone has a fascinating double life: a molecule with a precise chemical structure, it also has an outsize cultural presence, winning praise and blame for a wide range of characteristics typically associated with masculinity. Many of the claims go well beyond or even directly against the scientific evidence about what scientists call “T”.

Here are five myths about the hormone, disproved.

Myth No. 1: Testosterone is the male sex hormone

In answer to the question “What are male sex hormones?” the US National Institutes of Health says testosterone is one of the most abundant of the androgens, “a class of hormones that control the development and maintenance of male characteristics”. The website Live Science says testosterone “is a male sex hormone that is important for sexual and reproductive development”.

But T isn’t just a male hormone: it’s also the most abundant biologically active steroid hormone in women’s bodies – crucial for female development and well-being. It helps support ovulation, for instance. And T isn’t just a sex hormone, either. In men and women, receptors for the hormone are found in almost all tissues, and it contributes to lean body mass, bone health, cognitive function and mood, among other attributes.

Both testosterone and the supposed female sex hormone oestrogen were identified in the context of scientists’ search for the chemical essences of maleness and femaleness, an origin story that helps explain the tenacity of the “sex hormone” label. Another explanation may be the confusion of quantity with importance. Yes, men generally have much higher levels of T than women. But greater quantity doesn’t equate to greater function (elephants have bigger brains than humans, but brains aren’t more important to elephants).

Myth No. 2: Testosterone drives aggression and sexual violence

One of the most enduring storylines in discussions of testosterone is that “higher levels of the hormone cause aggression”, as the Guardian put it in 2017. A 2012 study in the International Journal of Endocrinology and Metabolism asserted that there’s “evidence that testosterone levels are higher in individuals with aggressive behaviour”.