In Iceland, 66 percent of babies are born out of wedlock. In Sweden, it's 55 percent, in Norway, 54 percent and in Denmark, 46 percent.
Why should Americans care? We're not the same culture, and our unwed birthrate is not even 40 percent yet.
The answer is that as unwed cohabiting takes over a culture, it alters the culture in ways big and small.
Cohabiting is escalating in America; do we really want our culture to become like Europe's?
To see the big picture, one must look at places where cohabiting is ingrained. Sociologist David Popenoe, former co-director of the National Marriage Project, did so, in a 2008 essay.
Europe's acceptance of cohabiting is clear, Mr. Popenoe said in "Cohabitation, Marriage and Child Well Being." A 2006 AC Nielsen global survey, for instance, asked 25,000 people if they agreed with the statement, "I consider a stable, long-term relationship just as good as marriage." More than 75 percent of Europeans said yes, compared with 50 percent of Americans.
One of the first results of widespread cohabiting is a reduction in the marriage rate.
In Europe, "with nonmarital cohabitation being the primary generating factor," many nation's populations have gone from being the most married in modern European history to the least married, Mr. Popenoe said.
Cohabiters also are more likely than married couples to enter and leave relationships, regardless of the presence of children. Thus, unwed childbearing and single parenting become more common. A massive 2006 British study, for instance, found that nearly half of cohabiting parent couples had split up by their child's fifth birthday; in Norway, children of cohabiters were found to be more than twice as likely to face parental breakup compared with children of married couples.
These fragmented families often need social support, so widespread cohabiting reinforces the need for expensive, government (i.e., taxpayer-funded), cradle-to-grave welfare systems.
Other international findings about cohabiters are that they are "less serious" about their relationships, "less satisfied" with their relationships, and more prone to domestic violence, child abuse and lower incomes than married couples, Mr. Popenoe noted. Moreover, even with fewer marriages, many European countries have rising divorce rates.
And Mr. Popenoe hardly touched on Europe's dismal fertility rates. In essence (and with cohabiting as one of many reasons), many European countries are looking at birth dearths. Millions of European women are having one or no babies.
Despite such unsettling outcomes, cohabiting is permeating the American culture.
Cohabiting supporters, such as John Curtis, author of "Happily Un-married, Living Together & Loving It," and the Alternatives to Marriage Project, defend cohabiting as normal, modern and even a right, since marriage isn't suitable for everyone. The Alternatives to Marriage Project, as one might expect, offers a bounty of positive advice, resources and suggestions about living together.
But there is no getting away from the mountains of research that call for caution about cohabiting.
My view is that if cohabiting is benign or good for couples and children, all this should be reflected in the outcomes — cohabiting adults should be famous for staying together, happily and faithfully, raising their children, prospering and growing old together. Think millions of Goldie Hawns and Kurt Russells.
Instead, the reality of U.S. cohabiting is more fully witnessed in America's black and Hispanic neighborhoods, where cohabiting has almost fully replaced marriage. Anyone who says cohabiting is not playing a major role in the repeated cycles of poverty, antisocial behavior and family heartache just isn't living in the real world.
And discussions of birthrates, marriage rates and welfare programs don't even get into the most important reasons America should fully resist widespread cohabiting. Cohabiting hurts.
Next week: It's all about the heart.
• Cheryl Wetzstein can be reached at firstname.lastname@example.org.