Remember The Population Bomb? This was Paul Ehrlich's Mathusian nightmare scenario from 1968, the idea being that population was growing so fast the Earth would be unable to sustain it.

Well, a funny thing has happened on the way to Armageddon. While the world now has nearly twice the population it did when Ehrlich wrote his book, the rate of growth worldwide is slowing. Some places are even de-populating.

That's the conclusion of Nicholas Eberstadt, of the American Enterprise Institute (from which the picture was taken). And it's not just happening in Japan and Europe, either.

For a population to remain stable, Eberstadt writes, each woman on average must have 2.1 kids. Why 2.1? Because stuff happens, OK?

Since early in the last century Europe has been falling further and further behind this "replacement rate" for births. Eberstadt says it's now at about 1.4. "Indeed, nearly all the world’s developed regions—Australia and New Zealand, North America, Japan, and the highly industrialized East Asian outposts of Singapore, Hong Kong, Taiwan, and South Korea— are reporting sub-replacement fertility. (Israel remains an exception.)"

But here's the real shock.

Apart from Mongolia, according to the Census Bureau, all of East Asia is sub-replacement, as are Thailand and Burma in Southeast Asia, Kazakstan and Sri Lanka in South-Central Asia, many Caribbean societies, and most South American countries.

Perhaps the biggest surprise, given received notions about the Arab/Muslim expanse, is the recent spread of sub- replacement fertility to parts of the Arab and the Muslim world. Algeria, Tunisia, and Lebanon are now sub-replacement countries, as is Turkey. And there is the remarkable case of Iran, with a current TFR of under 1.9, which is lower than the United States’. Between 1986 and 2000, the country’s TFR plummeted from well over 6 to just over 2. If modernization and Westernization are the handmaidens of sustained fertility decline, as is often supposed by students of demography, both terms are apparently being given a rather new meaning.

What does this mean? Grayer societies, fewer young workers able to bear the burden of old folks' pensions. This is a huge threat to China, which is now graying fast but without the wealth of, say, Japan and the U.S. (Russia is the real disaster, with a low birth rate and a high death rate due to alcoholism, especially among young men.)

Ebersteudt has three other big conclusions to share, all based on census data:

• Many countries, especially China, face a shortage of women, due to a parental preference for sons.
  
• Lifespans are not increasing as they did in the 20th century, in fact they're declining. AIDS is one big reason. Alcohol is another.
  
• America is the great exception. American women are currently bearing, on average 2.0-2.1 kids each. That's 50% higher than the rate in Europe. And you can't put the "blame" (or credit) on Hispanics -- Anglo fertility is at 1.84, much higher than the European rate.
  

This is a provocative article, with big implications. I'm looking for scientific criticisms, of his methodology, or the sources of his numbers, even his conclusions. That's the kind of debate I like, a scientific one.