World population growth may be slowing, but don't cheer yet. Slower explosion By Peter Brimelow IS THE POPULATION EXPLOSION ENDING? The United Nations reduced its world population projections recently. This cheered conservative and religious groups as evidence that the population explosion would go away without government promotion of birth control, abortion, etc. (see chart). In fact, many demographers expected that population would stabilize as technological and social limits were reached. And charted on a ratio scale, where a steady growth rate appears as an upward-sloping straight line, human population history loses much of that familiar terrifying exponential upswing (upper line, left scale). But don't cheer yet: • Even on a ratio scale, the recent explosion is historically exceptional—"consistent with the conventional understanding," says demographer Michael S. Teitelbaum, coauthor, with Jay Winter, of A Question of Numbers: High Migration, Low Fertility, and the Politics of National Identity (Hill & Wang, 1998, $26.00.) And even with the slowing, the U.N. projects that world population could reach 8.9 billion by 2050, up from about 6 billion today, and almost 11 billion by 2150. • Even if overall population is stabilizing, individual countries will grow partly because people redistribute themselves. Thus the U.S. population is authoritatively expected to expand by about half, to some 394 million in 2050, basically because of immigrants and their descendants (see inset chart). • This population explosion is actually the third in human history. The first began with the development of farming about 5000 B.C. It ended around A.D. 200 as the classical societies of Rome and China matured. The second began in A.D. 600-700, accelerating through the high medieval period in Europe. It ended around A.D. 1200-1300. Both previous population explosions did duly fizzle upon reaching the limits of then-available technology. Indeed, they overshot it. Disturbing thought: Both ended in catastrophe—invasions (Germans, Mongols), disease (the Black Death). Could that happen again? Are you a congenital optimist? Or a congenital pessimist? Put it this way: The good news is that, on present trends, there will be a lot more readers of FORBES here in 2050. The bad news: They might have to read it standing up. Research: Edwin S. Rubenstein, research director, Hudson Institute, Indianapolis. [EMAIL PROTECTED] A chart accompanying this article can be found at the following address. http://www.forbes.com:80/forbes/99/0125/6302058chart1.htm