Ever since official demographic records were first kept in Sweden back in 1749, women have outnumbered the men. In fact, that's a pattern that's common in just about every Western country in the world: Men are the minority. The main reason for the skewed gender balance simply comes down to life expectancy and behavior. Women live longer and tend to exhibit more risk-averse behavior, so at any given time there are simply more surviving women.

But something strange is happening in Scandinavian countries. First it was Norway, and now Sweden too. There are now more men than women, and their majority is increasing at an alarming rate. For instance, the tipping point in Sweden happened in March of 2015, when population statistics showed 277 more men than women. That's a pretty small difference, but in just one year the gap has grown to beyond 12,000. At this rate, the surplus in men in the region will be unlike anywhere else in the Western world, reports Phys.org.

"This is a novel phenomenon for Europe," said Francesco Billari, a University of Oxford demographer. "We as researchers have not been on top of this."

Statistics show that a few other countries aren't far behind. Denmark and Switzerland are nearing an even sex ratio, and the gap is also closing in places like Britain and Germany, countries that are still recovering from the demographic impact of seeing so many men die in two world wars within the last century.

So what is going on in Scandinavia and, more broadly, in Europe? The simplest explanation could be that men are simply living longer, healthier lives. Modern medicine and stable, historically efficient health care systems certainly help. One interesting demographic facet is that more men are born in these countries every year — there's a natural birth rate of 105 men to every 100 women. If men aren't dying at a faster rate than women, then the new demographic shift can be explained with simple math.

Nothing like some cross-country skiing through a snowy Nordic landscape to make you live longer. Many Scandinavian people stay active and healthy through cross-country skiing. (Photo: canadastock/Shutterstock)
It's also possible that a cultural shift is happening, whereby the definition of masculinity has changed, leading to less aggressive male behavior, and thus less risk-taking.

The arrival of large swaths of young new immigrants from places like Afghanistan, Syria and North Africa could be having an impact as well, though the statistics say that immigration alone can't explain the shift.

Whatever the reason for the gender shift, scientists are wondering about the kind of largescale changes this could mean for these countries and cultures moving forward. For instance, in places like India and China, where men have outnumbered women for generations due to a cultural preference for sons rather than daughters, violence against women and crime occurs at a higher rate.

That doesn't mean that Sweden and Norway — countries renowned for their gender equality — are headed down the same road. But it's unclear what impact this gender difference may have as it develops over the course of generations.

"The way in which masculinity works in different societies needs to be taken into account," cautioned Annick Wibben of the University of San Francisco.

One possible impact could end up being an increased bargaining power for women, allowing them to be choosier when picking a partner. Then again, nature could compensate. In many species, choosier females can lead to more aggressive competition among males for mates, which could tip cultural attitudes surrounding masculinity and male behavior back towards more chauvinistic times.