(CNN) Anyone who was even remotely plugged into pop culture in the 1990s can recall the Jennifer Aniston hairstyle. And who doesn't associate Anna Wintour, editor of Vogue magazine, with her signature bob.
But men have also sported their share of iconic 'dos over the decades, from the Beatles' shag to Justin Bieber's pompadour and the hard-to-ignore coif of Republic presidential candidate Donald Trump.
More and more, men seem to be caring about their hair. A small survey of men in Canada found that they are concerned about their locks and think it is part of their masculinity and self-image.
"It's increasingly acceptable to have [hair] concerns and to discuss those concerns ... it's not emasculating anymore," said Rose Ricciardelli, assistant professor of sociology at Memorial University in Newfoundland, and author of the study.
Men fuss with their tresses in large part to make themselves feel more comfortable or confident, Ricciardelli said. Many probably realize that people notice if they are balding, despite their best comb-over efforts, but they still want to look good when they look in the mirror, she said.
Of course, it is also about the outward show. Men who do more than just ask for a little off the top and sides tend to be more extroverted and care more about what others think of them, said Michael Cunningham, a psychologist who teaches in the Department of Communication at the University of Louisville.
Through hairstyle, men seek to blend in with their peers or look younger, more powerful or free-spirited, Cunningham said, and in most cases men succeed in conveying what they intend. They are aware of current style and social perceptions, he said, and they know what message they will sending if they tease their hair sky hair or grow some stubble.
The comb-over we all know and love (to hate) is achieved by combing long strands of hair over a bald spot. The style is a favorite among businessmen and politicians; the U.S. Congress is chock-full of comb-overs.
But a different kind of comb-over is taking hold among men with ample hair. "The comb-over is now defined as a strong side part where the hair is combed over to one side and cut tight around the edges to convey a very vintage look," said Sam Donofrio, educational supervisor at the Hair Design Institute in Manhattan. "It is probably the most popular hairstyle that we are seeing," he said. Some of Hollywood's most hirsute, including George Clooney and Christian Bale, sport these updated comb-overs.
The pompadour is another modern take on a vintage 'do that is popular among young and trendy men, Donofrio said. For this style, men build their hair up high on top and have it short and slicked back on the sides. Justin Bieber is one of the famous sporters of pompadours.
Although it is often referred to as a comb-over, the coif that covers Donald Trump's head is "an animal of its own," Donofrio said. And no, Donofrio has not really heard anyone asking for this style yet. An illustrated guide of how to achieve the look instructs you to first blow-dry your hair forward over your eyes, then flip it back and blow-dry again.
A bigger question than how Trump creates this flipped-back style, is why. "He wants to look like the brash young guy who is taking the world by storm...He wears this Beatles style haircut, but it doesn't quite work," Cunningham said. If Trump wanted to come across as an experienced senior business executive, he would probably go with a traditional, neat comb-over, he added.
Another possibility, which Ricciardelli suggested, is that Trump wears the flip because it is part of his brand, just like Bieber's signature pompadour. He would probably only change hairstyles if he was thinking of ditching the brand or reinventing himself, she said.
Or if he were moving into the White House. Trump has said that he'd lose the hairdo if he were elected president because he would not have time to maintain it.
About two-thirds of men in the U.S. lose a substantial chunk of hair by the time they are 35, and 85% have thinning hair by age 50. For some, the solution is hair transplantation, in which doctors graft patches of scalp where hair is growing onto balding areas. There have been advances in transplantation, also known as hair plugs, to make the new coverage look less patchy.
If Vice President Joe Biden got hair plugs, which many experts believe he did, he unfortunately received them decades ago, before those advances. Biden's hair plugs would have been larger than the kind used today, leaving a less natural looking hairline. A number of celebrities, including Matthew McConaughey and Tom Hanks, have been suspected of getting hair plugs because they have more hair these days than they used to.
As with comb-overs, hair plugs can be a way to keep a younger looking head. Even though thinning hair is common, some men just don't want any part of it, Cunningham said. "America values youth more than wisdom," he said.
Ricciardelli said a lot of men who get hair plugs tend to start balding at a young age, in their teens and early 20s. Some have told her they regret having the procedure, she said. Even in the best cases, hair plugs can leave scars and make the scalp less smooth and hard to shave, she said.
Baldness has not enjoyed a good reputation. A recent study found that both women and men perceived bald men as being more dominant and stronger looking than their hirsute counterparts.
Also less attractive. And older.
Other research over the years has found them perceived balding men as less assertive and less pleasant overall than their hair-endowed peers.
So, some men just quit fighting and shave it off.
"A lot of people have a tipping point of when it's time to go, and other people never lose enough hair that they really shave it, [but] if someone thinks they'll look younger for shaving it, they'll shave it," Ricciardelli said.
Some men start balding from the crown in addition to -- or instead of -- the front. In Medieval times, Christian monks would intentionally shave this bald spot and cut their hair around it short as a renunciation of vanity and display of religious devotion.
Were they on to something? Then, as now, balding conveyed wisdom, Cunningham said.
The real advantage to shaving it all off could be for men who have already lost a significant amount of hair. "They'll go for the full [shaved] look because it looks more athletic and less senior" than having thinning hair, Cunningham said.
The stereotype of the long-haired hippie exists for a reason. "In general, longer hair means that no one can control you, shorter hair means that you are working in a system," Cunningham said.
No surprise then, that young people and artists let their hair grow longer, whereas businessmen and politicians usually keep it cropped short. Other than Trump's flip-over, the only unusual hairstyle among the male Republican presidential candidates is Rand Paul's slightly longer, curly locks, Cunningham said. But as more of a libertarian, Paul may prefer to be a bit against the grain, and his hair is no exception, he added.
Long, flowing locks can sometimes be more about experimentation than rebellion, Ricciardelli said. "Males tend to grow their hair out when they are younger [to try] on something different when they have less responsibility," she said.
Unlike the tress-setting men who opt for pompadours and the style du jour, businessmen's cuts have not changed much over the years, Donofrio said. "These men aren't looking to set their style apart, they are just looking to have a clean haircut that is business savvy" that is clean on the sides and short on top, he said.
As every teenage boy knows, a little facial hair can make him look older and manlier in general. In one study, women looked at photographs of men and ranked the men as not just older but of higher social status if they had a beard. Looking at photos of bearded men and clean-shaven men with aggressive expressions, they rated the bearded men as more aggressive.
Men with facial hair can also send the message that they are renegades. Just the sight of a little stubble on the face of Rep. Paul Ryan, R-Wisconsin, was enough for the media to predict he probably not be running for president in 2016. In fact, there has not been a bearded presidential nominee for a major party since 1916. In professions such as politics and banking, you don't want to come across as not caring what other people think of you, Cunningham said.
However, a mustache or beard is not necessarily some great insight into the nature of the person wearing it, Ricciardelli said. "Some men have beards because they have very undefined chins or acne scars, so they do it to cover," she said.