REYKJAVIK, Iceland — Happy hour at the bar at the University of Iceland gets underway at 4 p.m. on Thursdays, the unofficial end of the week on campuses everywhere.

Like their counterparts all over the world, most of the students here avoid taking classes that are scheduled to meet on Fridays, giving themselves a head start on their weekends.

But that’s not what is most conspicuous about this scene.

It’s how women overwhelmingly outnumber men — evidence of a gender imbalance taking hold on college campuses throughout the world. And nowhere is the divide as lopsided as in Iceland, where there are now two women in college for every man.

The reasons for this, its implications and the thorniness of dealing with it make this sparsely populated nation a laboratory for countries heading in the same direction — including the United States, where the number of women in higher education has also surpassed the number of men.

Fifty years ago, 58 percent of U.S. college students were men. Today, 56 percent are women, Education Department estimates show. This year, for the first time, the share of college-educated women in the U.S. workforce passed the share of college-educated men, according to the Pew Research Center.

It’s not just that more women opt for college. It’s that fewer men do, affecting their opportunities and lifetime earnings.

“It’s a crazy cycle,” said Adrian Huerta, an assistant professor of education at the University of Southern California who focuses on college access and gender. “We know that when you have a college education, there are good outcomes with health. You’re more likely to live longer. It matters for employment stability and civic engagement. You’re less likely to rely on social services.”

While still less than 3 percent, unemployment for men in Iceland is slightly higher than it is for women, the government agency Statistics Iceland reports.

But even in Iceland, the shrinking number of men in higher education has, until recently, attracted scant attention, said Eyjolfur Gudmundsson, rector of the University of Akureyri, where 77 percent of 2,389 undergraduates are women.

“We are just now waking up and understanding that this is a problem,” Gudmundsson said. “The world is waking up to it.”

Yet some people still ask him why they should be concerned, Gudmundsson said.

“It is of concern for the exact reason that we had concern 30 years ago about women not being represented in higher education in a fair way, or in the United States about ethnic groups and people of different backgrounds” not going to college, he said he tells them.

“If you’re a young male able to get a blue-collar type of a job with a decent wage [and not go to college], that means physical labor. What are you going to do when you’re 50? What will be your opportunities then?”

The trend also complicates efforts to fill jobs that require a college education. In the United States, it is worsening an already historic decline in university enrollment.

“It’s not being discussed in the media,” said Steinunn Gestsdottir, vice rector at the University of Iceland. “But policymakers are worried about this trend.”

Though there are slightly more men in Iceland than women, women earn more undergraduate and graduate degrees, including PhDs, according to the country’s Directorate of Equality. Fifty-nine percent of women in the Reykjavik region have completed college, compared with 45 percent of men; outside the capital, the ratio is 40 percent to 19 percent.

The causes emerge in primary and secondary grades, with research showing that girls apply themselves earlier, whereas boys are more likely to drop out, impatient to begin earning money and unwilling to spend further years in school.

U.S. girls score higher than boys by the fourth grade in reading, and more boys than girls drop out of high school. In Iceland, more than 29 percent of boys drop out of high school, compared with 21 percent of girls.

“The boys want to have a car, but the girls want to think about their future,” said Agnes Orradottir, a University of Iceland undergraduate.

There’s a similar dynamic in the United States, Huerta said.

“You have some teachers and counselors in rural and urban environments discouraging young men from going on to higher education — ‘You’re not college material, you should just go work,’ ” he said.

When the mismatch went the other way, there was a focus on pushing women to attend college. Even now, there are programs to nudge more women into traditionally male-dominated fields such as engineering and computer science, which threatens to push the gender ratio even further out of whack.

“Women were told the reason you don’t get paid the same is you don’t have the education. So they went to university,” said Katrin Olafsdottir, an economist at the University of Reykjavik who studies gender inequality. “Everyone thought the men would be fine.”

Male high school graduates have ample opportunities in Iceland to take decent-paying jobs in major industries such as fishing and construction work that seem to be underway everywhere, while female classmates choose professions such as nursing that require further education.

This division by gender in many professions is unusually pronounced in Iceland, known as a society that values equality, with a female prime minister, a law requiring employers to certify they pay male and female workers equally and a rule that at least 40 percent of corporate board members must be women.

While men still predominate in engineering and computer science, they won’t go into nursing; 98 percent of nurses here are women, at a time when the need for nurses is rising.

When the nurses association announced last year that it would reimburse university registration fees for men who become nurses — about $605 a year, which is what students in Iceland pay for college — there were protests from women who questioned being excluded from getting the same incentive.

“Why should I have to pay more [than a man]?” University of Iceland student Claudia Magnusson asked.

This is not an issue only in Iceland. Women in China protested when universities made it harder for them to opt for certain majors in which they had begun to outnumber men.

To eliminate what the government calls “extreme gender imbalance,” universities in Scotland are working toward a 2030 target to make sure that no discipline has more than three-quarters of its students of one gender.

There are also shortages of teachers in Iceland, another job for which few men apply; at the University of Iceland, 91 percent of teaching students are women.

The teachers union, too, has tried to attract more men, but in this field, male role models may make the biggest difference. When the rock band that competed for Iceland in the Eurovision Song Contest in 2014 included two male preschool teachers, there was a brief increase in men who went into teaching.

Experts say small steps like this may overcome stubborn stereotypes that channel men into some roles and women into others.

In fact, attitudes toward work have started changing — but more among women than men. At the University of Iceland, more women have begun to enter male-dominated disciplines such as electrical engineering.

“What isn’t happening is the other trend in the female-dominated departments,” Gestsdottir said. “We’re not seeing men going into women-dominated subjects at the same rate. This is a very slow process.”

To discourage dropouts, high school was shortened from four years to three, though the effect of this has been mixed. Many students and some observers say schools have simply crammed the same amount of teaching into less time, alienating already disaffected students.

Those students are more often boys, said Ragnar Thor Snaeland, an undergraduate studying toward a law degree at the University of Iceland; he said he enrolled there because his parents, like most other parents in the Reykjavik suburb where he grew up, had gone to college and had expected him to go as well.

“In the countryside or maybe places in eastern Iceland, I don’t know if they have the same pressure there,” said Snaeland as he took a study break on the small campus of tightly clustered and interconnected buildings.

At the University of Iceland, the student council president is a woman. So are the chairs of all nine of its committees.

In Magnusson’s English major, there’s one man among 25 women, she said. “We don’t even hear from him.”

“They tone down when there are more women,” said Sandra Bjorg Ernudottir, who is studying ethnology, over nachos she was sharing with a friend at the campus bar.

There’s no one way to bring the ratio back into balance, Gudmundsson said.

“Some of it will be positive discrimination. Some will simply be messaging. Some will be about thinking about jobs in a new way so both genders will see it in a new way,” he said.

“We’re still just trying to understand the solutions, and I guess that’s the same for the rest of the world.”

This story about more women than men in college was produced by The Hechinger Report, a nonprofit, independent news organization focused on inequality and innovation in education. Sign up for our higher education newsletter.