And it's only getting worse.

http://online.wsj.com/article/SB10001424127887323375204578270053387770718.html?mod=googlenews_wsj

For more than three decades, Chinese women have been subjected to their country's brutal one-child policy. Those who try to have more children have been subjected to fines and forced abortions. Their houses have been razed and their husbands fired from their jobs. As a result, Chinese women have a fertility rate of 1.54. Here in America, white, college-educated women—a good proxy for the middle class—have a fertility rate of 1.6. America has its very own one-child policy. And we have chosen it for ourselves.

The root cause of most of our problems is our declining fertility rate.

The fertility rate is the number of children an average woman bears over the course of her life. The replacement rate is 2.1. If the average woman has more children than that, population grows. Fewer, and it contracts.

The nation's falling fertility rate underlies many of our most difficult problems. Once a country's fertility rate falls consistently below replacement, its age profile begins to shift. You get more old people than young people. And eventually, as the bloated cohort of old people dies off, population begins to contract. This dual problem—a population that is disproportionately old and shrinking overall—has enormous economic, political and cultural consequences.

Low-fertility societies don't innovate because their incentives for consumption tilt overwhelmingly toward health care. They don't invest aggressively because, with the average age skewing higher, capital shifts to preserving and extending life and then begins drawing down. They cannot sustain social-security programs because they don't have enough workers to pay for the retirees. They cannot project power because they lack the money to pay for defense and the military-age manpower to serve in their armed forces.

There's a constellation of reasons for this decline: Middle-class wages began a long period of stagnation. College became a universal experience for most Americans, which not only pushed people into marrying later but made having children more expensive. Women began attending college in equal (and then greater) numbers than men. More important, women began branching out into careers beyond teaching and nursing. And the combination of the birth-control pill and the rise of cohabitation broke the iron triangle linking sex, marriage and childbearing.

We must outsource our fertility. We've received a massive influx of immigrants from south of the border since the late 1970s. Immigration has kept America from careening over the demographic cliff. Today, there are roughly 38 million people in the U.S. who were born elsewhere. (Two-thirds of them are here legally.) To put that in perspective, consider that just four million babies are born annually in the U.S.

Taking Multiple Husbands Makes Sense

http://www.theatlantic.com/health/archive/2013/02/when-taking-multiple-husbands-makes-sense/272726/

Historically, polyandry was much more common than we thought.

Rather than treating polyandry as a mystery to be explained away, Starkweather and Hames suggest polyandry constitutes a variation on the common, evolutionarily-adaptive phenomenon of pair-bonding -- a variation that sometimes emerges in response to environmental conditions.

We can also create lots of test-tube babies and let gay couples raise them

These ideas are just a start; other measures certainly will be needed to avert a demographic disaster in the U.S. If we want to continue leading the world, we simply must figure out a way to have more babies.