Masculinity is shaped by a combination of biology, psychology, and culture, and no single factor defines it. Testosterone drives the physical traits most people associate with maleness, like a deeper voice and greater muscle mass, but psychological traits like decisiveness and self-reliance also play a role. What counts as “masculine” has shifted considerably over time, and the current understanding reflects both deep evolutionary roots and rapidly changing social expectations.
The Role of Testosterone
Testosterone is the primary hormone behind most physical traits associated with masculinity. During puberty, it triggers a cascade of changes: the larynx grows and the voice deepens, body and facial hair develop in specific patterns, bones lengthen and thicken, and skeletal muscle grows through increased protein synthesis. These are called secondary sex characteristics, and they’re the visible markers that distinguish adult male bodies from female ones.
In adulthood, normal testosterone levels for men 18 and older range from about 193 to 824 nanograms per deciliter. Those levels naturally decline with age, which is why older men tend to experience reduced muscle mass, lower bone density, increased body fat, and a drop in sex drive. But there’s also a broader trend at play: population-level testosterone has been falling by roughly 1.2% per year since at least the late 1980s. A large dataset tracking men from 2002 to 2011 found the proportion with clinically low testosterone rose from 35% to over 47%. Even young men at peak hormone levels have seen declines, with average levels at age 21 dropping measurably between 2006 and 2019. The cause isn’t fully explained by rising obesity rates, suggesting environmental or lifestyle factors are also involved.
Physical Traits Linked to Masculinity
Men carry significantly more skeletal muscle than women, both in absolute terms (about 33 kg versus 21 kg on average) and as a percentage of body weight (38% versus 31%). The difference is more pronounced in the upper body, where men have roughly 40% more muscle than women, compared to 33% more in the lower body. This upper-body advantage is one reason broad shoulders and a muscular chest are so strongly associated with a masculine appearance across cultures.
Facial structure also plays a part. Prominent jawlines and brow ridges are the features most consistently linked to perceived masculinity. Research in evolutionary psychology shows these traits signal physical strength and dominance, and they influence how others judge a man’s social standing. Men with more masculine facial features are rated as more formidable, which affects everything from social hierarchies to mate preferences. Interestingly, men themselves are especially sensitive to these cues on other men’s faces, picking up on subtle differences in jaw width or brow prominence more readily than they do on women’s faces.
Psychological Traits and Personality
When psychologist Sandra Bem developed one of the most widely used tools for measuring gender-typed traits, the traits she categorized as masculine were largely “instrumental”: taking the lead, being competitive, acting decisively, defending one’s beliefs, and being self-reliant. A shortened version of her inventory, tested across different populations, consistently found that leadership ability, strong personality, dominance, and decisive action cluster together as a recognizable masculine profile.
These aren’t traits exclusive to men, of course. But they describe a pattern that cultures around the world have historically expected from men: a bias toward action, independence, and willingness to assert authority. Whether these tendencies are more nature or nurture remains debated, but they show up early in development and persist across very different societies.
How Men Tend to Communicate
Communication style is one of the more subtle markers of masculinity. Linguistic research consistently finds that men lean toward direct, authoritative statements and use language to assert knowledge, control topics, and establish their position in a group. Men are more likely to interrupt in mixed-gender conversations, and those interruptions tend to be disruptive rather than supportive, functioning as a way to steer the discussion.
Men also gravitate toward language about objects, tools, and competitive activities rather than emotional or relational topics. This isn’t just a stereotype. It shows up in studies of workplace conversations, casual social settings, and even online communication. The pattern aligns with the broader psychological profile: a task-oriented, competitive approach to interaction that prioritizes information exchange over emotional connection.
Traditional Masculinity and Its Costs
For most of modern history, the dominant model of masculinity in Western cultures has revolved around a few core expectations: strength, toughness, emotional stoicism, independence, and dominance over others. Sociologists call this “hegemonic masculinity,” and it shapes how boys are raised, how men relate to each other, and what behaviors get rewarded or punished in social settings. Men who fit the mold gain status. Men who don’t often face ridicule or exclusion.
The costs of this model are well documented. The expectation to be stoic discourages men from seeking help for mental health problems. The emphasis on dominance can fuel aggression and make it harder to form emotionally close relationships. Traditional masculinity norms also include the sexual objectification of women and hostility toward gay men, both of which serve to reinforce a narrow definition of what it means to be a “real man.” These aren’t just cultural quirks. They have measurable effects on men’s health, relationships, and life expectancy.
How Masculinity Is Changing
A systematic review of research on contemporary masculinities found that younger, middle-class men in Western cultures are increasingly adopting a different set of values while still holding onto some traditional ones. Four themes emerged from across the studies.
- Inclusivity: Greater acceptance of homosexuality, declining homophobia, and a genuine desire for gender equality, in direct contrast to the exclusionary stance of traditional masculinity.
- Emotional intimacy: Willingness to share feelings and be emotionally vulnerable with male friends, breaking from the stoic norm that discourages men from expressing anything beyond anger or humor.
- Physical affection: Increased comfort with intentional touching between male friends, like hugging, which older models of masculinity treated as suspect.
- Active resistance: Conscious rejection of traditional masculinity norms, with some men deliberately embracing traits like compassion and empathy that were previously coded as feminine.
These shifts don’t mean traditional masculinity is disappearing. Most men still value strength, decisiveness, and independence. What’s changing is the rigidity of the script. The newer models, sometimes called “inclusive masculinity,” allow men to be strong and emotionally open, competitive and compassionate, without treating those combinations as contradictions.
Biology, Culture, and Everything Between
What makes a man masculine ultimately depends on which layer you’re looking at. Biologically, it’s testosterone and the physical traits it produces: muscle mass, bone structure, facial hair, a deeper voice. Psychologically, it’s a cluster of instrumental traits like decisiveness, self-reliance, and a willingness to lead. Socially, it’s a set of expectations that vary dramatically by time, place, and community.
None of these layers operates in isolation. Testosterone influences behavior, but culture determines which behaviors get labeled masculine. A man with a prominent jaw and deep voice may be perceived as more dominant, but whether dominance is valued or seen as threatening depends entirely on context. The most useful way to think about masculinity is as a spectrum shaped by biology and filtered through culture, not a single checklist with a passing grade.