"There is a widespread belief that it is ‘natural’ for men to be violent," UNESCO expert Robert W. Connell wrote in a 2000 piece on masculinity and violence. "There is often an appeal to biology, with testosterone in particular, the so-called ‘male hormone,’ as a catch-all explanation for men’s aggression. Careful examination of the evidence shows that this biological essentialism is not credible." The current position among many theorists is that blaming male violence on testosterone is, in the words of a 2016 report, "spurious" and based on incomplete ideas.

Scientific research backs this thesis up: a 2009 report out of the University of Zurich found that, contrary to common belief, testosterone does not inherently cause aggressive or risky behavior; rather, the research suggested that the hormone instead "increases the sensitivity for status." A similar study conducted in 2016 concluded that their "findings are inconsistent with a simple relationship between testosterone and aggression" and that their research suggested "a more complex role for testosterone in driving status-enhancing behaviors in males" than simply pushing aggression.

So if men aren't born with the qualities we think of as "innately masculine," like a tendency towards aggression, where do those traits come from?

According to many researchers, men often act violent because they grow up in cultures where violence is equated to masculinity. In the U.S., for example, the kind of masculinity that men are supposed to aspire to "promotes ideals such as emotional stoicism, physical strength, aggressiveness, competitiveness, and independence that characterize men’s importance by their ability to be autonomous, powerful, and in control to the exclusion of other, more sensitive traits", Sara Tyberg wrote in a 2016 study of masculinity in school shootings.

And how does violence become such a baked-in part of the masculine experience? Michael Kaufman, an expert on gender-based violence, has a famous theory known as the "triad of violence," in which he argues that men are taught to be violent to women, other men, and themselves because "male-dominated societies are not only based on a hierarchy of men over women but some men over other men. Violence or the threat of violence among men is a mechanism used from childhood to establish that pecking order." A 2016 series of interviews with men by American researchers confirmed this; they wrote that "men’s constructions of violence and their justifications for engaging in violence were linked to their constructions of masculinity and what it meant to them to be a man."

"I think in my experience, both in school-era mocking and in self-perception in later years, there is definitely a strong relationship between potential for...violence [and] manliness."

Kaufman's theorized that these three kinds of violence reinforce one another, particularly in a cultural context in which men are meant to redirect their other emotions primarily into rage and fear; that's the "violence against oneself" bit. (Hence the plethora of news stories about men resorting to angry violence to solve problems, like getting service trucks to move away from your house.)

Men themselves back this idea up. The five men who talked to Bustle for this article repeatedly mentioned that their own identity was in some way dependent on being "macho." Matt, 27, tells Bustle, "I think in my experience, both in school-era mocking and in self-perception in later years, there is definitely a strong relationship between potential for...violence [and] manliness." "I feel to some extent less manly in a macho, cliche heterosexual way, because I know I'm not strong, not intimidating and have no idea how to fight," Matt notes.

Many men I spoke to also noted an extreme awareness of the relationship between expected "manliness" and aggression. "It's not that I think my own identity is defined by violence," Alexander, 31, says. "I'm just deeply uncomfortable with the tie between masculinity as an abstract concept [and] violence. I find it deeply unsettling." In general, he tries to distance himself from this equation — but it is still unavoidable in his life. "On occasions when I've felt that shows of physical force were necessary, in self-defense, or when working in bars, I've felt quite shaken up about it afterwards, not just because of the incident itself, but because it raises questions about how I view myself in relation to masculinity."

This doesn't mean that all men, in the U.S. or anywhere else, believe that their masculine value is in their ability to be aggressive or exert physical force. But as a rule, men are exposed to and subjected to these cultural values, and many people expect them to measure up to them. According to many researchers, these expectations play into why violence and masculinity are so deeply linked in our culture.

"Men who feel 'unmanned' will exaggerate their height, number of past sexual partners, and other stereotypical markers of 'manliness'—this confusion and fear about their perceived status or power is a driving force behind a lot of male violence."

It's been a long-standing argument that men are more violent because they're "reinforcing" their power at the top of the cultural totem pole in patriarchal situations. But thinkers today are challenging that. Specialist on masculine violence Dr. Michael Kimmel declared in his 2007 essay “Contextualizing Men’s Violence: The Personal Meets the Political" that masculinity is not "the experience of power; it is the experience of entitlement to that power." And Michael Kaufman noted in his ground-breaking 1999 essay "The Seven P's of Male Violence," "Although maleness and masculinity are highly valued, men are everywhere unsure of their own masculinity and maleness, whether consciously or not."

Sometimes, the behavior produced when men scramble to recover threatened masculinity can be relatively harmless — the research of Professor Benoit Monin, in studies published in Social Behavior in 2015, found that men who feel "unmanned" will exaggerate their height, number of past sexual partners, and other stereotypical markers of "manliness." However, the dark side is obvious —this confusion and fear about their perceived status or power is a driving force behind a lot of male violence. In a 2016 series of interviews with American men, published in the Journal of Interpersonal Violence, the study authors concluded that "violence was viewed as necessary in particular situations to assert or maintain one’s social status and sense of self as masculine when faced with threats to manhood status."

This belief can be seen in cases like that of Elliot Rodger, whose mass shooting in Isla Vista in 2014 was, according to his writings, partially motivated by his feelings about perceived lack of female desire for him. "I don't know why you girls aren't attracted to me, but I will punish you all for it," he said in a video shot before the massacre.

Tara Tober and Tristan Bridges of the University of California, Santa Barbara, authored an influential piece of research in 2015 about the link between American masculinity and mass shootings; after analyzing studies about what fuels male violence, they wrote "The research does not suggest that men are somehow inherently more violent than women. Rather, it suggests that men are likely to turn to violence when they perceive themselves to be otherwise unable to stake a claim to a masculine gender identity."

A 2016 study bore this theory out — according to a report in Pacific Standard, researchers found that the stress a particular man felt regarding the discrepancy between "how masculine [he] feels, and how that self-image stacks up against societal expectations" was an indicator of potential for violence. While men who felt that they comfortably embodied "masculine norms" were the group most likely to have committed violence, men "who consider themselves less than truly masculine, and who feel tense or anxious as a result of that nagging perception" were also likely to act violently — these men who were anxious about their own masculinity "reported rates of assaults causing injury 348 percent higher than men low on discrepancy stress."

It's worth noting that a staggering number of men who go on to engage in mass violence have backgrounds filled with domestic abuse. A 2017 report showed that one quarter of the men who had committed lethal violence with a political motivation since 2001 had been accused of domestic violence or sexual crimes in the past, and anti-gun violence group Everytown found that 16 percent of mass shooters from 2009 to 2015 had been charged with domestic violence prior to their shooting — a group that includes people from Pulse shooter Omar Mateen to Virginia Tech shooter Seung-Hui Cho to Congressional shooter James Hodgkinson to Planned Parenthood shooter Robert Lewis Dear. Charlottesville's James A. Fields purportedly engaged in domestic violence against his mother, too.

In light of this sort of research, there's a growing call to relabel misogyny, the prejudice against things that aren't male (and would therefore be threatening if they were powerful), as a form of extremism. Not all people are comfortable with this — but given the strength of the relationship between aggrieved masculinity and violence, it makes sense.

Thinking of misogyny as extremism, Tober and Bridges told Bustle, "is a useful way of discussing the ways that gender inequality is tied to the structure of society in such a way that gender itself is political."

"Suggesting that the hatred of women is deeply connected to the organization of many societies is a claim we're sure many will find... appalling," they said. "But statistics about violence against women, gender segregated workplaces, wage gaps, and more at the very least suggest that misogyny could arguably be considered a form of extremism."

Misogyny, it must be remembered, also plays a large role in a more recognized and organized form of extremism — terrorism. Dr. Michael Kimmel, an expert on men and masculinities, also studied terrorist groups in 2003 and found that, from the far right in Europe to extremist groups in the Middle East, masculinity is actually a recruiting tactic to get new troops into the fold; female terrorists do exist within these groups, but they're anomalies. Professor David Plummer has examined hypermasculine posturing in ISIS/ISIL and elsewhere, and noted in 2016 on "The Conversation" that the imagery and performance of violence basically functions among young terrorists as a method of "coming of age" into manhood. And Heidi Beirich, director of the Intelligence Project at the Southern Poverty Law Center, reflecting on Charlottesville, called the U.S. white supremacist movement a "toxically masculine movement" whose philosophy both extols violent racism and has "pretty retrograde views about what women should be doing."

The idea of masculine violence as a bonding activity doesn't just happen in terrorist groups. Alec, 25, tells Bustle that at his British boarding school, "on your first night you would get beaten up by some of the other older boys, some of them men really, as a test of strength, which was seen as more or less all that mattered." This sort of hazing story was common among the men who spoke to Bustle, specifically in all-male communities; one remembered physical tussles where the "loser" would be hit with the other boys' genitalia. "The worst part, looking back," says Alec, "was that in a twisted way, it worked. I knew if I fought tooth and nail, as hard as I could, I would be more trouble than I was worth, and that would be the more or less the end of it. Some of the other kids were less fortunate. They were bullied without mercy, and it was seen as their fault for not demonstrating sufficient toughness."

"Violent masculinities," Tober and Bridges tell Bustle, "are integral features of global terrorism today." Not just because "terrorism is enacted primarily by groups of young men. Most of the terrorism in the U.S., for instance, is enacted by right-wing extremist men;" but also because "politicians (almost exclusively men) curry favor within their own societies by crafting discourses of protectionism whereby they suggest that only through their violence and protection can the rest of us truly be safe."

Our cultural ideas about masculinity can cause a lot of real-world harm —especially for men themselves. The Representation Project's film The Mask You Live In, which documents the pressure on young boys to be a "real man" in modern America, shows that violence is a part of a toxic equation that also results in higher suicide rates and addiction levels. Jennifer Siebel Newsom, who wrote and directed the film, tells Bustle that "it’s not an exaggeration to say that our notions of masculinity are literally killing people." In addition to the fact that, according to the CDC, men account for 77.9 percent of all deaths by suicide in the U.S., Newsom notes that "90 percent of homicide offenders are male — with almost 50 percent being under the age of 25.... We have a public health crisis on hand, and toxic masculinity is the thread that runs through these shocking statistics."

Figuring out how to challenge masculine violence is, Tober and Bridges say, "a difficult question." "There is some evidence," they tell Bustle, "that suggests that as women gain power, income, and authority in societies in which they have been denied these things, we see spikes in violence against women following these gains. This is key to understanding gender as political and gender inequality and change as complicated.

"But we also have evidence suggesting that pushing for change does work. It changes laws, it alters what we had previously understood as possible. And speaking up and fighting back collectively have always been tools of the oppressed that always have the potential to provoke change."

The other task is to remodel masculinity itself, but they warn that it's a complex goal. "Remodeling masculinity," they said, "is something that requires coordinated efforts across a range of institutions in society. To get more men to stay home or to share work/family balance issues more equitably, we also need work/family policies in workplaces that promote these changes. Violence inflicted by men is glorified across a range of social institutions in our society — from video games and movies, to sports, to schoolyard pushing matches. A world in which conceptions of masculinity were not rooted in violence would be a world much safer for everyone. It's worth continuing to question this connection and pushing the idea that the connection between masculinity and violence may exist, but men are not hardwired this way by nature."

This questioning isn't just theoretical; plenty of activist organizations are taking action on the ground to help men develop less harmful ideas about masculinity. Brown University, for example, has an entire program devoted to detoxifying masculinity, including a storytelling series and interviews, while organizations like A Call To Men are targeting high school boys to educate them on "healthy, respectful manhood". Somewhat remarkably, even men's body wash company Axe — a company once known for its sexist commercials — has attempted to enter the conversation, with an ad campaign about the many struggles men face regarding the concept of masculinity. The company has also partnered with a number of non-profits that use education to fight against masculine stereotyping. Axe tells Bustle, "Research commissioned by Axe and conducted by Promundo revealed that 65 percent [of men] have been told that 'a real man' should behave a certian way. We want guys to see there's no wrong way to be a man and no holds barred on how they should act, look and feel."

It's foolish to say some ads will change the face of modern masculinity, or that ideas about masculinity are the only issue in the toxic soup that leads to violent events like Charlottesville. But awareness about where our ideas of manhood come from, and what kinds of destruction they create, is a crucial first step in overcoming the toxic, harmful concepts of masculinity that puts our lives in danger. After all, as Tober and Bridges tell us, "Masculinities are organized by societies; and this means they can be disorganized and reorganized, too."