To what extent does testosterone drive male behavior? The answer should help inform our expectations for how any hormone contributes to behavior.
When talk turns to human behavior, especially of the more aggressive kind, someone will eventually bring up testosterone. Why are there more men in prison than women? Well, you know, men have more testosterone. Why has nearly every war been started by a male leader? Surely that hormone of competition and conquest, testosterone, has been at it again. Why (according to the persistent myth) are men more promiscuous than women? It’s obviously that puppet master, testosterone, dictated over by the evolutionary need to spread the seed.
And yet, if that’s all true—if our behavior comes down to hormones—what choices do we really have in our lives? And why do we punish people for just doing what comes naturally?
British philosopher and psychologist Cordelia Fine is only one of many who have been digging through the research on testosterone in recent years. The title of her 2017 book sums up the hormone’s reputation in a neat metaphor: Testosterone Rex, abbreviated in the text to “T-Rex.” “It’s true that we don’t, as a rule, tend to think that the scientific facts of nature dictate how things should be,” she acknowledges. “Just because a scientist says that something is ‘natural’—like male aggression or rape—obviously doesn’t mean we have to condone, support, or prescribe it.” True. Nevertheless, who among us hasn’t witnessed a bout of questionable male behavior being excused with an elbow to the ribs, a wink-wink, and a sly chorus of “Boys will be boys, eh wot?”
Indeed, among the so-called sex hormones, testosterone stands out, a giant dragon animated by what scientists Rebecca Jordan-Young and Katrina Karkazis have called “the heavy thrum of T folklore.” Many believe that this hormone (which, as we see, these authors refer to simply as “T”) is the source of what are often considered strongly male traits: aggression, risk-taking, athleticism and promiscuity, to name a few.
But setting aside provocative media headlines and premature conclusions from limited studies, what does the research actually say about the supposed influence of testosterone on behavior, and how do folk ideas about this hormone tie in—even to how researchers approach the subject? Does testosterone drive masculine behavior the way we’ve long assumed it does? If not, what does that say about our expectations for how any hormone contributes to our behavior?
What sort of hormone is testosterone anyway? We know that it’s lipid-derived; that it’s classed as a steroid hormone, as are estrogen and progesterone; and that cholesterol is the precursor to these and other steroid hormones. As simple and straightforward as that may sound, the presence and role of testosterone in the body is far from straightforward.
In fact, say Jordan-Young and Karkazis in their 2019 book Testosterone: An Unauthorized Biography, “the apparent simplicity of this molecule is an illusion.” In their critical excavation of the scientific findings about T, the nuanced picture that emerges is quite different from the hormone’s legendary reputation. To begin with, they point out, “like all steroids, T is in a constant flow of generation and transformation. Some T will act directly on cells, but some will be transformed into its ‘downstream’ steroids, estradiol (estrogen) or dihydrotestosterone.” T is not produced only in the male testes for traits we typically identify as masculine. It’s also produced in healthy female ovaries and adrenal glands, and not in trace amounts as outdated information may have led us to believe. Regardless of sex, it is now known, testosterone acts in concert and balance with other hormones, and often in a secondary role, as we’ll see.
“The singularity of T is an illusion, and the importance of context is profound.”
If Google search results are any indication, however, the last 80 years or so of testosterone research may as well never have happened. A surprising number of returns still neatly compartmentalize testosterone as the male sex hormone and estrogen as the female sex hormone. Yet a deeper dive uncovers the rather confusing admission that low estrogen levels in men can create many of the same infertility and dysfunction issues as high levels. And newly emerging research on fertility suggests that—against long-accepted ideas—androgens, including testosterone, play a key role in female ovulation. Further, what we like to think of as “sex hormones” aren’t in fact restricted to sex; they influence bone development, heart function and liver metabolism, among other things.
The understanding is slowly dawning that testosterone’s role and level in the body (whatever one’s biological sex) depend on myriad factors, including what’s happening outside the body. Athletes, for instance, show variances in testosterone levels during their off-season as opposed to their training and competitive seasons. By no means a stable trait even within an individual, testosterone levels vary from one activity to the next over the course of a day.
Julia Shaw, a prominent criminal psychologist in London, takes on some of the myths about the power of testosterone in her 2019 book, Evil: The Science Behind Humanity’s Dark Side. Shaw points out that the earliest studies of testosterone, which involved roosters and set the stage for its larger-than-life reputation, were conducted in the 1800s and made the process look pretty simple: “Add testosterone, get more aggression. Remove testosterone, get less aggression.” But fast-forward a couple of centuries, and we have access to a much larger body of research that challenges that simple initial view. Now the question has become: Could we have the testosterone-aggression link the wrong way around?
“What is potentially more interesting [than how testosterone drives aggression],” says Shaw, “is how behaviour affects the production of testosterone, and then how testosterone affects behaviour. . . . As we compete with one another, our testosterone levels increase, and this increase can lead to more aggression.”
In 2017, a group of researchers headed by Justin Carré reviewed the scientific literature on the subject and found some notable trends. In broad terms, “testosterone concentrations are higher in men and women convicted of violent crimes in comparison to those convicted of nonviolent crimes” (emphasis added). But why? We could (unscientifically) jump to the conclusion that people with elevated testosterone levels (both men and women) tend to commit violent crimes. “However,” writes Carré, “equally plausible is that people who commit violent crimes are also more aggressive while in prison, which may transiently increase testosterone.”
This makes reasonable sense in the world of hormones. Most of us are familiar with the idea that cortisol rises in response to stress to equip us to meet that stress. Why wouldn’t testosterone rise in situations of competition and aggression for the same reason? In fact, the interplay between cortisol and testosterone (and, indeed, other hormones and chemicals) is an emerging area of interest for some researchers.
“We suggest that future research consider the potential role of other hormones (e.g., cortisol) and personality traits as moderators of the relationship between testosterone and human aggression.”
Under the heading “Competition-Induced Changes in Testosterone,” Carré and his group continue the thought-provoking theme of which comes first, the T. rex or the aggression. In studies measuring testosterone levels in athletes before and after competitions, winners showed an increase in their levels afterward, while those defeated showed a decrease. Even more interesting is that the effect also extends to spectators. Fans of the winning team? Testosterone increase. Fans of the losing team? Well, you get the picture. Some studies even showed a sort of cycle in men that didn’t occur in women: winning touched off a rise in testosterone levels, which then led to further aggression. Why didn’t it lead to further aggression in women? The reason is still unclear, but this may be where social conditioning comes into play.
The Role of Self-Control
As background to the idea that social conditioning plays a part, consider what Carré found with another group of colleagues in a 2014 study. This was a long-term program focused on at-risk youth. In kindergarten, one group of children was assigned to a 10-year intervention program, meaning, in this case, that they were given social-cognitive-behavioral therapy (social-CBT). Boiled down to its essence, this is simply training aimed at teaching people to regulate their own behavior. The control group of children received no treatment. Twenty years later (that is, 10 years after the program ended for the intervention group), both groups were tested for testosterone reactivity and for aggression. The group that had received social-CBT as children showed less aggression in response to social provocations compared to the control group.
The takeaway, in case it needs emphasizing, is that early training had a clear effect on whether testosterone levels rose and led to aggression in response to provocation.
In light of some of these findings, it’s easy to see why Shaw has a “point of contention with evolutionary theories” that suggest testosterone is in the driver’s seat of male aggression. “Humans have the capacity for inhibition,” she points out. “Predispositions don’t make some people commit murder; their own decisions do that.”
She relates a personal experience at a friend’s 10th birthday party. The friend was called in to open her presents and sat obediently next to the pile of beautifully wrapped boxes, waiting for her parents to give the signal for her to open them. Just then, however, “her five-year-old brother stormed into the pile and started tearing the presents apart.” Shaw recalls that her friend started crying while the parents sat idly by, watching her brother’s “boyish” antics in amusement.
“Whenever people say that boys will be boys, that sexist comments are just locker-room talk, or that men are just naturally more violent than women, I think of stories like this one,” writes Shaw.
Had the five-year-old been a daughter, would the parents have sat by smiling while she tore into someone else’s presents? Shaw’s implication, of course, is exactly what other researchers have shown: our expectations of children have a direct influence on their behavior. And while it may be impractical for children of certain ages to sit still for long periods of time, it’s certainly to everyone’s benefit to teach boys, as well as girls, appropriate behavioral boundaries. Indeed, each of us could likely think of scenarios where boys who were taught empathy and compassion grew up to be nurturing fathers without sacrificing any of the more traditional, positive traits we might associate with masculinity.
“Society often gives too much leeway to destructive, aggressive and violent actions carried out by men. This is bad for women, . . . but it might be even worse for men.”
“When we rationalise male aggression as natural and normal,” Shaw continues, “we accept that men are more likely to be convicted of crimes, end up in prison, and be victimised by other men. But why should our prisons be filled with men? Is this not a disastrous situation for males? Gender inequality on how we educate boys and girls on violence and aggression is hugely problematic. If we want violence and murder rates to go down, this is something we can, and must, change.”
Looking a little deeper into why men show more aggression than women, some researchers have been able to think outside the box. In 2004, John Archer of the University of Central Lancashire reviewed the catalog of research, which was by no means meager even back then. The studies looked at types of aggression, levels of anger involved, and a host of other aspects. Their findings? As we might think, men were far ahead of women in the use of physical aggression, although women used verbal aggression nearly as often as men (surprisingly, men came out slightly ahead there as well). However, levels of anger didn’t differ between the two sexes.
If the level of anger isn’t so different between men and women, why were men more reactive in these studies? Is it that, as evolutionary theorists propose, men have been born to aggression because of their ancient roles as hunters and defenders? Or that, as Shaw frames the argument, “testosterone hijacks men’s brains and makes them act out”? But even if a hormone could be blamed for aggressive acts, why don’t all men act aggressively?
Surely self-control plays a key role. Building self-control is often compared to building muscle. The more we use this “moral muscle,” as some have called it, the stronger it becomes.
Psychologist Roy Baumeister defines self-control as “what people use to restrain their desires and impulses. More precisely, it can be understood as the capacity to override one response (and substitute another). It is largely synonymous with ‘self-regulation’, a term preferred by many researchers because of its greater precision. To regulate is to change; namely, change in the direction of some standard, some idea about how something could or should be. Self-regulation thus means changing responses based on some rule, value or ideal.”
In the context of hormones, this applies to more than just the male population, of course, and to more than just testosterone. Barring certain neurological and mental health conditions, most of us can strengthen our ability to control our behavior, resisting the urge to act out—our hormones notwithstanding.
Another “T” Word
“Teach your children well,” sang Crosby, Stills & Nash. This is another “T” word, and when we talk about behavior change, it’s the first and greatest step. As the song goes, “you, who are on the road, must have a code that you can live by,” but such a code has to be taught. And if the goal is a less aggressive and more compassionate society, that code needs to emphasize the fact that real strength is displayed by self-control, concern and cooperation rather than by conflict, competition and conquest. This goes equally for men and women, since all of us are capable of aggressive behaviors, whether directly, indirectly or passively.
Jordan-Young and Karkazis say the idea that it’s testosterone that leads to these behaviors is “like a zombie”; it should long ago have been laid to rest by new research, yet it continues to walk the earth without substance and “won’t die.” It undermines not only our personal relationships but our social institutions.
Testosterone, we’re beginning to find, is not the author of all the worst of male aggressive or risky behavior. Rather, say Jordan-Young and Karkazis, “it’s a transcendent, multipurpose hormone that has been adapted for a huge array of uses in virtually all bodies.”
May the zombie finally forever rest in peace, done in by new understanding that should lead us to expect more from ourselves.