Fewer babies? No worries
NEARLY half of all people now live in countries where women, on average, give birth to fewer than 2.1 babies - the number generally required to replace both parents - over their lifetimes.
This is true in cities like Melbourne and Moscow, Sao Paulo and Seoul, Teheran and Tokyo.
It is not limited to the West, or to rich countries; it is happening in countries as diverse as Armenia, Bhutan and Qatar.
At just over two births per woman (down from nearly four in 1957 at the peak of the baby boom), the United States is more fertile than most other rich countries.
In large, emerging economies where labour is still relatively cheap - countries like Brazil, Russia, Iran - fertility rates have fallen steadily since the 1980s.
Very high national fertility rates have not disappeared, but they are now mostly concentrated in a single region: sub-Saharan Africa.
Last year, all five countries with estimated total fertility rates (the average number of births per woman) at six or higher - Niger, Mali, Somalia, Uganda and Burkina Faso - were there.
So were nearly all of the 18 countries with fertility rates of five or more (the exceptions were Afghanistan and East Timor).
This is news to many people, and also a source of alarm - mostly in the West.
In his book, What To Expect When No One's Expecting, Mr Jonathan V. Last, a senior writer at The Weekly Standard, described a "coming demographic disaster" from "America's baby bust".
Mr Steven Philip Kramer, a professor at the US' National Defense University, says rich countries with low fertility should adopt "pronatalist" policies to close "the baby gap".
Even the usually sober Economist recently warned about "the vanishing Japanese".
These dark prophecies have a long history, and they are as misguided as they are unoriginal.
Former US president Theodore Roosevelt warned of Anglo-Saxon "race suicide" and, during the Depression, books like Twilight Of Parenthood (1934) caught the Western public's imagination.
Why do commentators treat this worldwide trend as a disaster? It could be because declines in fertility rates stir anxieties about power: national, military and economic.
In reality, slower population growth creates enormous possibilities for human flourishing.
In an era of irreversible climate change and the lingering threat from nuclear weapons, it is simply not the case that population equals power.
Lower fertility is not entirely a function of rising prosperity and secularism; it is nearly universal.
The new hand-wringing stems from a gross misunderstanding of the glacial nature of population change.
Since the early 1950s, total fertility rates have mostly dropped all over the world.
Even when the total fertility rate falls below 2.1, the "momentum" effects of earlier fertility trends will keep a population growing for many decades.
In cases when the absolute size of a national population declines, the drop often turns out to be short-lived, and slight in aggregate numbers.
Rapidly declining fertility - especially if rates go very low - does pose challenges. Yet it also can provide substantial benefits.
First, fertility decline is associated nearly everywhere with greater rights and opportunities for women.
The deferral of marriage and the reduction of births to two, one or none across so much of the world are broadly consistent with the higher education and career aspirations of young women.
Second, the workforces of societies with low-to-moderate fertility rates often achieve higher levels of productivity than do higher-fertility societies.
This is one reason China's economic growth far outstripped India's from 1970 to 2010 - a period when fertility declined rapidly in China (though only partly because of the one-child policy, now being relaxed) but did not decline as much in most of India.
The fewer children who need primary and secondary education, the more resources there are that can be invested in higher-quality education per child and in expanding access to higher and continuing education for teenagers and young adults.
Third, by enhancing the employment and career experiences of young adults, lower fertility can also bring about greater social and political stability.
High-fertility societies commonly produce large numbers of young adults who have trouble finding productive employment.
Finally, lower fertility rates may gradually reduce the incentives that have led a large number of governments to encourage the emigration of their own young citizens, both to find work and send home hard-currency savings.
Such policies - sometimes explicit, sometimes implicit - can be seen in countries like Mexico, the Philippines and Pakistan.
With the global economy still fragile, it is a safe bet that ominous jeremiads about endangered, geriatric societies will continue.
Population doom of one kind or another is a recurring fad. But like most fads, this one can be safely ignored. Humanity has many legitimate problems to worry about. Falling fertility is not one of them.
This is an excerpt from an article first published in The New York Times.
Michael S. Teitelbaum, a senior research associate at Harvard Law School, and Jay M. Winter, a professor of history at Yale, are the authors of The Global Spread Of Fertility Decline: Population, Fear, And Uncertainty. It was also published in The Straits Times.