For as long as I can remember, the population "time bomb" - the danger of too many people - has hovered over the world with the seemingly relentless certainty of death and taxes.
Along with it has come talk of dire consequences: increased competition for scarce resources and, potentially, conflict; the inability of globalization to keep pace and share its promise with an ever-larger percentage of people; and a devastating impact on the environment, especially to the extent that humans affect climate change.
Now, though, as explored by a summer cover story in The Economist, counter-intuitive circumstances are emerging. For a variety of reasons, including the fact that women in several countries are having fewer children, a decreasing population appears likely.
Skeptics will insist that the notion is speculative, that current projections by some of a peaking of the world's population at approximately 10 billion by the middle of the 21st century will not necessarily happen. After all, we have been witnessing nothing but the relentless rise of the global headcount.
As the magazine notes, however, the United Nations concluded last year that the global fertility rate could tumble below replacement by 2025. Indeed, non-replacement rates already have arrived for much of the world's population.
So, is that not reason for optimism? After all, a smaller-than-anticipated population should mean easier access to resources, the spreading of globalization's wonders and a less-stressed environment.
Resources will not suddenly multiply, nor will greed diminish. The world is still growing faster than its capability to broaden amenities for the entire population. And far too many developing nations - led by China - claim a hard-to-dispute right to use fossil fuels as aggressively and unabashedly as developed countries did in their earlier stages of growth.
But the apparent turn in the global population does create some interesting possibilities. One is under-population, which some observers might welcome. Taken to the extreme, such a trend could portend a decline serious enough to threaten humans' presence on Earth, although I have little concern about that.
More worrisome, as The Economist rightly suggests, is the central and real challenge of a shrinking percentage of capable, well-educated young people. When one combines that demographic change with the mounting pressure on already-strained public retirement systems by the departure of older workers, the predicament is evident.
How to respond?
First, by making the best use of capable people, with an emphasis on ensuring that women have fairer access to education, training and opportunities at all levels.
Second, in nations where population decline is most serious, by considering reasonable, carefully monitored incentives for citizens to have larger families.
Third, by allowing - indeed, encouraging - competent people to work beyond artificial retirement deadlines. Otherwise, societies will continue to squander unique assets.
Finally, by having a practical, orderly, consistent way of welcoming imported talent, which in the United States would require moving beyond self-defeating politics, such as the recent debacle over immigration reform. Immigration offers a partial solution and a two-way benefit, given that so many people in places that struggle under burgeoning populations seek to relocate to countries facing declining fertility rates.
At day's end, whether the world's population is shrinking or expanding, more proactive ingenuity and less chatter about calamity would aid in reaching for global equilibrium.