Population Booms and Busts Nicholas Eberstadt, "Four Surprises in Global Demography," AEI On the Issues, August 2004 (aei.org)
AEI scholar Nicholas Eberstadt has identified four important developments in global population trends. First, there is now widespread "sub-replacement fertility." In order to maintain its population (absent immigration), a nation requires about 2.1 births for each woman. All of Europe and East Asia is at a sub-replacement level, as are most Caribbean and South American countries. Even in the Muslim world, Algeria, Tunisia, Lebanon, and Turkey have sub-replacement fertility, while Iran has seen a collapse in births from six per woman in 1986 to 1.9 today.
This means that countries are aging rapidly, with the problem particularly acute in China. Eberstadt explains that "Apart from the family, China lacks any functional nationwide arrangements for pensioning its elders. Thus, a great many Chinese will have to continue to work into old age. But working life in China typically entails more physical labor, which does not favor the frail.... China's aging problem has the makings of a slow-motion humanitarian tragedy."
In many countries, there are surprisingly large gender imbalances in births. Naturally, around 105 boys are born for every 100 girls. But in China, the ratio has now reached 120:100. In Punjab, India, the ratio is 126:100. This almost certainly reflects "a collision between an immensely strong cultural preference for sons, new regimens of sub-replacement fertility, and a diffusion of ultrasound and other technologies that permit prenatal gender determination" via selective abortion. …