One often hears from people with far-right views that immigrants are a threat to "our women." Now, there's empirical confirmation that perceived competition for female attention is a key factor behind anti-immigrant hate crime.

Rafaela Dancygier, Naoki Egami and Amaney Jamal from Princeton University and Ramona Rischke from Humboldt University in Berlin have published a paper in which they mapped German hate crime statistics onto the country's mating market. They found the incidence of hate crime was higher in municipalities with a relative shortage of women, especially in those where there's a surplus of low-earning men, who face the toughest competition for women. (As elsewhere, German women choose mates from at least the same social group as themselves, but preferably a higher one.)

Intuitively, a correlation like this feels spurious. Men are more violence-prone than women, so places where men outnumber women should see more violence in general, including more hate crime. Besides, places where men earn little are often depressed industrial areas where immigrants can be unwanted competitors for jobs, cheap housing, social assistance and other scarce resources of which women aren't necessarily the most important one. Finally, because women are supposed to be interested in more successful mates, it's difficult to see poor, frequently unemployed, linguistically challenged refugees as strong competitors to local men.

Yet the research paper shouldn't be dismissed for these reasons.

The intuition about more crime in areas with a surplus of men is incorrect. In 2016, a University of Utah study showed violence and criminality are in fact higher where men are rare. In such places, men are less likely to marry and settle down: They are spoiled for choice and subsequently more prone to misbehavior.

Besides, Dancygier and collaborators were extra careful to control for other hate-inducing factors, such as perceived competition for jobs and benefits. Statistically, the relationship between heightened competition for women and hate crime still held.

In addition to using hate crime statistics collected by the Amadeu Antonio Foundation and Pro Asyl, a data set that adds information from the news media and nonprofit organizations to official data from the German police, the researchers ran their own field study with 3,000 respondents. It confirmed that in areas with more men, and specifically with more low-earning men, male respondents were indeed the most worried about competition with immigrants for local women. And those who displayed the most such concern were also the biggest supporters of violence as a last resort in keeping away unwanted immigrants.

Although the more than 1 million asylum seekers who have settled in Germany since 2015 are overwhelmingly poor and not yet well-integrated, it's quite conceivable that German men can see them as competitors. Conditioned for years to take a more modern view toward women and romance, some of them, especially those on the lower rungs of the social ladder, fear that German women will prove more responsive to the Middle Easterners' more traditional masculinity. That, in turn, can prompt more violent behavior. Dancygier and collaborators wrote:

"In situations characterized by a mating market squeeze (e.g., due to a surplus of men) these opportunities are restricted, presumably even more so for men who rank low on the socioeconomic ladder. Engaging in anti-migrant violence may then be one outlet to express masculinity, in particular for males who are being challenged by refugees whose supposed 'raw masculinity' is perceived as making them especially attractive to native women."

There's plenty of anecdotal confirmation for these findings in Germany. Dancygier and collaborators mentioned, for example, the unhealthy climate around "flirt coaches" who have attempted to train new immigrants from the Middle East and Africa in the rules of effective, and socially approved, interaction with German women. Some of these coaches have been forced to hire private security or ask for police protection because of threats from right-wingers.

Right-wing websites and social network accounts are full of worry about "migrants taking our women." It's often framed as concern about women's safety in light of events like the December 31, 2015, mass attacks on women near the Cologne Central Station. Dancygier and collaborators, however, point out that this is likely a disingenuous spin on competitive reasoning: "Attitudes towards women among right-wing extremists are usually quite misogynistic, and violence against women is not problematized. Tellingly for our account, when far-right forces present immigrant men as sexual predators, they frequently make possessive claims to 'their' women."

If the Dancygier theory is correct, that, of course, doesn't mean other reasons for anti-immigrant violence aren't valid. In Germany, as in other countries, the areas with significantly more men than women are predominantly rural and poor: It's more often women than men who move to the cities from such places. Such communities often tend to be closed, even hostile to outsiders - and immigrants from non-Western cultural backgrounds stand out there more than they would in a big city. And there's no way to exclude economic factors, the prevalence of hate-spreading social networks, the historical strength of far-right movements.

But if Dancygier and collaborators are right, it challenges the often-expressed view (I generally hold it, too) that most immigration problems can be solved with strong, intelligent action on integration. Integrating new immigrant populations doesn't fix the problem of competition for women - in fact, it may exacerbate it.

If the mating competition aspect is indeed important, the German authorities made a mistake in sending immigrants to the country's poorer rural areas, often those where they could be quickly housed in empty buildings. It would have been more expensive, but smarter, to house them where the male-female ratio was balanced. That mistake could eventually fix itself as more of the asylum seekers learn German and seek their fortunes in the bigger cities, but so far, it's been creating tension in the country's relatively poor post-Communist east and in small western towns.

| Bloomberg News Leonid Bershidsky, Bloomberg News.

Leonid Bershidsky is Bloomberg Opinion’s Europe columnist. He was the founding editor of the Russian business daily Vedomosti and founded the opinion website