Whether it's Donald Trump bragging about the size of his hands (and, err, something else), a shirtless Vladimir Putin riding a horse in the mountains, or Hollywood promoting buff heroes like Superman and Captain America, masculinity is often used to symbolize strength and glory.

Not surprisingly, Americans say they look up to masculine men more than feminine women, according to a Pew study released this month.

But it's not just gender that dictates these beliefs. Racial makeup and political affiliation play a role: Republicans are more likely than Democrats to describe themselves as masculine. Black men and women are also more likely than whites and Hispanics to identify as "very masculine" or "very feminine," Pew found from its survey of 4,573 people across the nation.

To explain what's behind these differences, local professors of gender and race studies weighed in.

When it comes to race …

This may be a result of racial stereotypes, said Heath Fogg Davis, a political science professor at Temple University who focuses on issues of gender and race. Society tends to value black men more for their physical abilities than intellectual abilities, he explained, which causes black men to perceive masculinity — especially physical masculinity — as a symbol of strength.

"Stereotypes have an impact on how people think of themselves and how they're valued," Davis said. "American society values and valorizes black male professional athletes, and this heavy association with the body and physical strength."

[Read the story: Conflicting identities: Being black and gay in Philadelphia]

White men, on the other hand, are valued by society more for their intellectual abilities — how much economic and social success they can attain — than their physical prowess, Davis said.

"One of the hallmarks of white privilege," he said, "is that you get to be more associated with the mind than the body."

When it comes to role models …

That's because masculinity is associated with strength, logic, rationality, and leadership, said Shauna MacDonald, co-director of Villanova University's gender and women's studies program.

"According to these ideas that we've created of gender, men should be masculine, and we have an understanding of what that looks like: It's powerful, it's strong," MacDonald said. "So we want to admire that. We want to aspire to that power."

Being a woman, on the other hand, can be associated with being emotional, nurturing, and even weak, she said. Pew found that, too: Women were much more likely than men in the survey to describe themselves as nurturing or sensitive.

"We're caught up in believing this fiction that we've all created for ourselves — that masculine equals powerful, feminine equals less powerful," MacDonald said. And that mindset starts at a young age. Think about what parents sometimes teach, she said: Rugged trucks are for boys; nurturing dolls are for girls.

When it comes to politics …

More men, particularly white men, identify as Republicans. More women and people of color identify as Democrats.

The ideology of each party also influences opinions about masculinity. As MacDonald notes: "The Republican is more associated with tradition," or ideals like being the "man of the house" or the breadwinner of the family.

When it comes to transgender individuals, a divide also appears: Less than 20 percent of Republican-leaning individuals say a person's sex can be different from that at birth, compared with 64 percent of Democratic-leaning individuals, a separate Pew survey found this year.

Some conservatives have suggested men are becoming weak because they lack traditional values of strength and hard work. The National Review said in an article titled, "Men are getting weaker — because we're not raising men" that today's young men are "exactly the kind of person who in generations past had your milk money confiscated every day."