The Truth About Testosterone and Aggression

Is it your high testosterone levels that won’t let you be dissed without throwing a retaliatory punch, or is it something else? Info here.

Testosterone is linked to aggression in humans and most animals. Generally speaking, the higher the testosterone levels in a particular human or particular animal species, the higher their level of aggression… or at least that’s the presumption.

The animal with highest recorded levels of testosterone – at least among mammals – is supposedly the post-hibernation black bear, measuring in at an impressive 6,000 nanograms per deciliter of angry blood (compared to about 1,100 nanograms per deciliter, at the top end, in humans).

But do these ridiculous levels of T cause the black bear to act more aggressively than other animals? To anyone who’s been mauled by a black bear, the answer would have to be hell yes.

Things get murky, though, when you start looking at other species. Compared to the alleged testosterone levels of certain salamanders and frogs, bears wear little pink ballerina skirts and prance around the forests while dreaming of dancing in Swan Lake, which is silly because, you know, bears dressed like swans.

These half-aquatic, half-land creatures supposedly have between 20,000 and 40,000 nanograms of T per deciliter blood, which is 3 to 7 times higher than bears.

Of course, it’s not easy to tell if these impressive levels of male hormone have made them more aggressive. After all, there just haven’t been many reports of campsites being raided by amphibians that busted through an Igloo cooler to get to an open package of Oscar Mayers.

But what about humans with high T? While the terms “testosterone poisoning” and “roid rage” are commonly heard, are they based on real things? Or are they linked to reactions based on subjective beliefs about testosterone’s tendencies rather than a real, physiological response to certain situations?

German researchers decided to find the answer.

What They Did

The Germans enlisted 103 men between the ages of 18 and 35 and divided them into two groups. Members of one group received 5 grams of testosterone gel, which contained 50 milligrams of testosterone. The second group received a gel without any active ingredients.

After receiving the gel, the men were required to play several rounds of a computer game, the winners earning more money than the loser. The players assumed they were playing against someone else in the study; in fact, they were even introduced to their alleged opponent, who was then led to another room. In reality, though, the players were playing against the fiendish German scientists and their rigged computers.

In some rounds of play, the participants won money. In others, they lost, with the amounts varying. The players also had the ability to “punish” their opponents by levying a fine against them, a fine that didn’t benefit the assigner of the fine at all.

The researchers regarded these fines as signs of aggression and wanted to know if the testosterone gel increased the number and amount of fines levied.

Granted, playing video games and testing player’s responses might not be the most dramatic way to test the effects of testosterone on aggression, but it’s easy. While it might have been more instructive to have some test subjects drive slowly down the fast lane in a Prius while being tail-gated by testosterone-enhanced BMW drivers and counting the horn blasts, raised middle fingers, rammings, or shots from a handgun, the computer game was much more ethical and less problematic.

What They Found

The men who’d received the testosterone gel “punished” their opponents more than those who received placebo. Oddly enough, the men who thought they had received T tended to punish opponents at a higher rate, too.

The researchers made the following conclusions:

  • T administration increases retaliatory behavior, especially in situations in which the social status of males is endangered.
  • T administration does not generally increase aggression per se, but increases tit-for-tat behavior: The higher the provocation, the higher the punishment; the lower the provocation, the lower the punishment.
  • Neural processing of reward and social threat seems to be altered under T.
  • The belief to have received T might actually enhance frustration and leads to an increase in aggressive behavior.

What This Means to You

This study seems to corroborate what many men who live and work in highly masculine, high-testosterone environments (like the gym, for example) have seen and/or experienced: While steroid users, or men who naturally have high levels of testosterone (as evidenced by their behavior, appearance, and preferences) don’t usually go out of their way to be assholes, they’re much more sensitive to being dissed.

However, this study gives us something more to chew on by suggesting that men on steroids might be more reactive to perceived sleight because of the knowledge that they’re juiced. This bit of self-awareness ends up being a self-fulfilling prophecy, leading to more assholed-ness.

So if you’re on T replacement or steroids, remember that you’re the captain of your ship. It might not be the testosterone or the steroids making you act like a jerk. It just might be you.




  1. Wagels, Lisa, et al. “Exogenous Testosterone Enhances the Reactivity to Social Provocation in Males.” Behav. Neurosci., 02 March 2018.