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The Population Sink

Philip Longman and the decline of populations.

12:00 AM, Jun 7, 2006 • By JONATHAN V. LAST
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PHILLIP LONGMAN is the most important man you've never heard of in Washington.

A senior fellow at the liberal New America Foundation, Longman specializes in demography. If you're a romantic, demography is the science of love, writ large. If you're a cynic, it is the sausage factory of civilization. Whatever your disposition, demography is, if not destiny, then a subject of paramount importance. In the long run, no weapon, no technology, no economic system is more powerful.

Longman has spent many years studying demographic trends, and the conclusions are unsettling. As he writes in his 2004 book, The Empty Cradle, birthrates in America and around the world are declining beneath sustainability; population growth is slowing and, unless the trends of the last 200 years change, will soon bring about population decline--and with it, potential shifts in global prosperity and power.

Forget domestic politics and international relations: Fertility is the thing. As Longman explains, it's the grand unified theory of everything. As fertility rates decline, populations, then economies, then military power, then world influence, diminish.

This is a bit counterintuitive. As Longman notes, everywhere you look there are signs of overcrowding. More traffic, more housing sprawl, more strip centers, more kids applying to college. It looks as if the world is bursting at the seams.

There's some truth to that. There are 6.5 billion people today, and that number is increasing every year. But according to demographic estimates, the world's population will peak somewhere between 9 billion and 12 billion in the next 75 years--give or take--and after that will precipitously decline, while the average age of the population gets more and more advanced.

The key concept is that of fertility rates. The "replacement fertility rate," which is to say the number of children the average woman needs to bear for a population to sustain itself, is 2.1.

Global fertility rates have been declining for a long time. Today, they're half of what they were in 1972. Fifty-nine countries (accounting for 44 percent of world population) have fertility rates below replacement levels. The United Nations projects that by 2050, 75 percent of all countries will fall below replacement levels.

Let's be clear: Even as fertility rates decline, absolute population size continues to increase because of demographic momentum. But as the fertility rate decreases, the rate of population increase slows--until you dip beneath the 2.1 line. Suddenly, the pool of potential new parents becomes too small to sustain the population. After about 30 years, the grandparents begin dying off.

"By then, the momentum of population growth is lost," writes Longman, "or, more precisely, is working in the opposite direction with compounding force."

You can already see this trend in the United States. We have the highest fertility rate in the industrialized world (2.09), but this mainly reflects the contribution of our immigrants, who reproduce at a higher rate than natives.

As Colgate economist Michael Haines has shown, American fertility rates have been falling steadily for 200 years. In 1800, the fertility rate among white Americans was 7.04; by 1998, it was 2.07. This decline was interrupted by only a single period of increase: the Baby Boom. In 1940, the fertility rate was 2.22; in 1950, it rose to 2.98; in 1960, it rose further still to 3.53. But by 1970, it fell back to 2.39 and has been headed south ever since.

The fertility rate for black Americans is in steeper decline. In 1850, it was 7.90. Blacks, too, experienced a Baby Boom between 1940 and 1960, but by 1998, their fertility rate was 2.17 and falling fast. Hispanics are the only American ethnic group significantly above the replacement level, because Latin American immigrants bring with them higher fertility rates. After a few years in the States, they begin regressing to the mean: Between 1990 and 2001, America's Hispanic birthrate fell 10 percent.

Immigration might seem like a solution to our demographic woes, but that's a mirage. As the U.N. report "Replacement Migration" explains, to keep the current ratio of workers to retirees in America, we'd need 10.8 million new immigrants every year until 2050, at which point the U.S. population would be 1.1 billion, 73 percent of whom would be immigrants arrived since 1995 and their descendants. As a sociological matter, that's an untenable situation.

(It's also unlikely. Manhattan Institute scholar Tamar Jacoby persuasively argues that falling fertility rates and rising median ages in Latin America will probably cause the source of immigration to dry up long before our need for bodies is satisfied.)