Population: What to Do When There Are Too Many of Us

By Robert Engelman, Island Press. Posted June 10, 2008.

Editor's Note: The following is an excerpt from More: Population, Nature, and What Women Want by Robert Engelman. Copyright 2008 by the author. Reproduced by permission of Island Press, Washington, D.C.

All historical eras are shaped by the material and environmental realities of their time. Our own reflects the adjustments society and nature have made to accommodate the unprecedented 6.7 billion human beings now alive. And those changes are dramatic. The planet is warming dangerously as a result of the heat-trapping byproducts of our daily lives. Half of the primeval forests that existed at the end of the last ice age are gone. A mist of mercury and other toxic metals from coal combustion falls continuously on land and ocean, and to eat fish is to absorb these metals yourself. Half of us are now urban, rarely if ever meeting up with creatures wilder than crows, cockroaches, and, in some cities, packs of feral dogs.

And this is just where we are today, while the beat of growth goes on. Little if any of this would have transpired had human numbers peaked long ago. Such a peak might have occurred by now, even with the gains in life expectancy of the past century, if the status and reproductive intentions of women had found consistent support rather than silence and censure.

Beginning little more than a century ago, social acceptance of contraception began to grow and to spread around the world. That led to dramatic declines in birthrates that gathered force as human population throttled past a few billion. Who knows how much closer we would be to a meltdown of Greenland's ice or the collapse of critical ocean fisheries had this collective wisdom -- a public good derived from individuals acting in their private interest -- not dampened the rise of population? Given the increasingly plausible threat of one or more interacting environmental catastrophes, the slowing of population growth is a triumph of human wisdom and good fortune. This realization is only slowly dawning, however, on the community of journalists and other opinion leaders.

The dominant concerns in many countries about population aging and decline are hardly baseless. These developments may well challenge societies. Populations may have more old people than young for a while, because yesterday's baby boomers are heading toward old age even as young women are having fewer children. Over time, however, extreme age disparities should subside as these large generations pass on, the more so when average fertility returns to close to two children per woman. Assuming it will.

Some demographers, eyeing the stubborn low fertility of women in most of Europe and parts of east Asia, are beginning to wonder if such a return to replacement fertility is possible. Some allude in cautionary tones to the possibility of a "low-fertility trap," a vast pool of demographic quicksand that prevents women from ever returning to replacement fertility once their childbearing average drops below about 1.5 births. There's no real basis for such speculation, however. The world is too dynamic and our experience with intentionally low fertility far too new.

What might eventually unfold is something far more appealing: birth cohorts of consistently equal size across generations. The most demographically stable age structure for a population would be for each year's "class" of babies to be the same size as the one the year before, and ten, twenty-five, or fifty years before. No single age group, young or old, would naturally claim any more of society's attention than any other, at least based on their numbers. That's a population structure worth striving for.

For now, population aging is the inevitable outcome of two of the most positive developments of modern times: longer life spans and the realized intentions of women to have fewer children, later in their lives. Modern views on human rights and equality hardly would have allowed most women to continue giving birth to many more children than they wanted. And populations hardly could have continued growing in the twenty-first century at the same torrid pace as in the middle decades of the twentieth. Some populations had to be the first to experience the leveling off of growth and then decline, and in most cases this has occurred with no significant increases in death rates. That's rare, maybe even unprecedented, in human history.

Today, humanity still grows by 78 million people annually-the rough equivalent of a new Texas, California, and New York each year. Unless death rates rise catastrophically or birthrates plummet far more than anyone expects, the end of world population growth is still decades away. It's reasonable to expect that humanity will grow to 7 billion, 8 billion, or even higher before the number levels off for good reasons or bad.

What dominates our experience in the first decade of the third millennium are the technologies and institutions we have invented, disseminated, tinkered with, and improved over thousands of years to make human life on such scales possible. We've done well. Not only are more people alive than ever, but most of us live longer than our ancestors did. Quite a few of us spend our entire lives in comfort and with tools and toys that those ancestors never could have imagined.

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Robert Engelman is vice president for programs at the Worldwatch Institute. Formerly vice president for research at Population Action International and founding secretary of the Society of Environmental Journalists, he has served on the faculty of Yale University. His writing has appeared in Nature, The Washington Post, and The Wall Street Journal.

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