International Herald Tribune
Demography has never been an exact science. Ever since social thinkers began trying to predict the pace of population growth a century or two ago, the people being counted have been surprising the experts and confounding projections.
Today, it is happening again, as stunned demographers watch birthrates plunge in ways they never expected.
Only a few years ago, some experts argued that economic development and education for women were necessary precursors for declines in population growth.
Today, village women and slum families in some of the poorest countries are beginning to prove them wrong, as fertility rates drop faster than predicted toward the replacement level 2.1 children for the average motherone baby to replace each parent, plus a fraction to compensate for unexpected deaths in the overall population.
A few decades ago in certain countries such as Brazil, Egypt, India and Mexico, fertility rates were as high as 5 or 6.
As a result, United Nations demographers who once predicted that Earth's population would peak at 12 billion over the next century or two are scaling back their estimates. Instead, they cautiously predict, the world's population will peak at 10 billion before 2200, when it may begin declining.
Some experts are wary of too much optimism, however.
At the Population Council, an independent research organization in New York, John Bongaarts has studied population declines in various countries over the last half century. He questions the assumption that, when fertility declines begin, they will continue to go down at the same pace, especially if good family-planning services are not widely available.
Some Clear Trends
Sharp fertility declines in many industrialized and middle-income countries had already challenged another old belief: that culture and religion would thwart efforts to cut fertility.
In Italy, a Roman Catholic country whose big families were the stuff of cinema, family size is shrinking faster than anywhere else in Europe, and the population is aging rapidly as fewer children are born. Islamic Iran has also had great success with family planning.
"Projections aren't terribly accurate over the long haul," said Nicholas Eberstadt, a demography expert at the American Enterprise Institute in Washington, D.C.