How Many Is Too Many?

Biologists have argued for a century that an ever-growing population will bring the apocalypse. Economists argue that man and markets will cope—so far none of the predicted apocalypses have arrived. The near-term questions, though, are political, and they are overlooked in the fierce battles

BY CHARLES C. MANN

IN 1980, WHEN I WAS LIVING IN NEW YORK CITY, IT CAME TO MY ATTENTION THAT the federal government was trying to count every inhabitant of the United States. In my building—subject, like many in New York, to incredibly complicated rentcontrol laws—a surprising number of apartments were occupied by illegal subtenants. Many went to elaborate lengths to conceal the fact of their existence. They put the legal tenant’s name on the doorbell. They received their mail at a post-office box. They had unlisted telephone numbers. The most paranoid refused to reveal their names to strangers. How, I wondered, was the Census Bureau going to count these people?

I decided to find out. I answered an advertisement and attended a course. In a surprisingly short time I became an official enumerator. My job was to visit apartments that had not mailed back their census forms. As identification, I was given a black plastic briefcase with a big red, white, and blue sticker that said U.S. CENSUS. I am a gangling, six-foot-four-inch Caucasian; the government sent me to Chinatown.

Strangely enough, I was a failure. Some people took one look and slammed the door. One elderly woman burst into tears at the sight of me. I was twice offered money to go away. Few residents had time to fill out a long form.

Eventually I met an old census hand. “Why don’t you just curbstone it?” he asked. “Curbstoning,”I learned, was enumerator jargon for sitting on the curbstone and filling out forms with made-up information. I felt qualms about taking taxpayers’ money to cheat. Instead, I asked to be assigned to another area.

Wall Street is not customarily thought of as residential, but people live there anyway. Some live in luxury, some in squalor. None were glad to see me, even though I had given away the damning U.S. CENSUS briefcase to my four-year-old stepson. The turning point came when I approached two small buildings. One was ruined and empty. The other, though scarcely in better condition, was obviously full of people, but not one of them would answer the bell. In a fit of zealotry I climbed through the ruin next door. Coated with grime and grit, I emerged on the roof and leaped onto the roof of my target. A man was living on it, in a big, dilapidated shack.

He flung open his door. Inside I dimly perceived several apparently naked people lying on gurneys. “Go away!” the man screamed. He was wearing a white coat. “I’m giving my wife a cancer treatment!”

My enthusiasm waned. I jumped back to the other roof. On the street I sat on the curbstone and filled out a dozen forms. When I was through, fifty men, women, and children had been added to the populace of New York City.

PROFESSIONAL DEMOGRAPHERS ARE NOT AMUSED BY this sort of story. This is not because they are stuffy but because they’ve heard it all before. Finding out how many people live in any particular place is strikingly difficult, no matter what the place is. In the countryside people are scattered through miles of real estate; in the city they occupy nooks and crannies often missed by official scrutiny. No accurate census has ever been taken in some parts of Africa, but even in the United States, the director of the Census Bureau has said, the last official count, in 1990, missed more than five million people— enough to fill Chicago twice over. If my experience means anything, that number is low.

It’s too bad, because How many are we? is an interesting question. Indeed, to many people it is an alarming question. For them, thinking about population means thinking about overpopulation—which is to say, thinking about poverty, hunger, despair, and social unrest. For me, the subject evokes the vague unease I felt toting around The Population Bomb, which I read in school. (“It’s Still Not Too Late to Make the Choice,” the cover proclaimed. “Population Control or Race to Oblivion.”) In other people it evokes the desire to put fences on our borders and stop the most wretched from breeding.

The Population Bomb appeared twenty-five years ago, in 1968. Written by the biologist Paul Ehrlich, of Stanford University, it was a gloomy book for a gloomy time. India was still undergoing a dreadful famine, Latin American exports of grain and meat had dropped to pre-war levels, and global food production was lagging behind births. More than half the world’s people were malnourished. Nobel laureates were telling Congress that unless population growth stopped, a new Dark Age would cloud the world and “men will have to kill and eat one another.” A well-regarded book, Famine 1975!, predicted that hunger would begin to wipe out the Third World that year. (Fortunately, the book pointed out, there was a bright side: the United States could increase its influence by playing triage among the victims.) In 1972 a group of researchers at MIT would issue The Limits to Growth, which used advanced computer models to project that the world would run out of gold in 1981, oil in 1992, and arable land in 2000. Civilization itself would collapse by 2070.

file projections failed to materialize. Birth rates dropped; food production soared; the real price of oil sank to a record low. Demographers were not surprised. Few had given much credence to the projections in the first place. Nonetheless, a certain disarray appeared in the work of what Ansley Coale, of Princeton’s Office of Population Research, calls the “scribbling classes.” Doubts emerged about the wisdom and effectiveness of the billion-dollar population-control schemes established by the United Nations and others in the 1960s. Right-wingers attacked them as bureaucratic intrusions into private life. Critics on the left observed that once again rich whites were trying to order around poor people of color. Less ideological commentators pointed out that the intellectual justification for spending billions on international family-planning programs was shaky—it tacitly depended on the notion that couples in the Third World are somehow too stupid to know that having lots of babies is bad. Ehrlich dismissed the carpers as “imbeciles.”

Population has become the subject of a furious intellectual battle, complete with mutually contradictory charts, graphs, and statistics. The cloud of facts and factoids often seems impenetrable, but after peering through it for a time I came to suspect that the fighters had become distracted. Locked in conflict, they had barely begun to address the real nature of the challenge posed by population growth. Homo sapiens will keep growing in number, as everyone agrees, and that growth may have disagreeable consequences. But those consequences seem less likely to stem from the environmental collapse the apocalyptists predict than from the human race’s perennial inability to run its political affairs wisely. The distinction is important, and dismaying.

Cassandras and Pollyannas

HOW MANY PEOPLE IS TOO MANY? OVER TIME, the debate has spread between two poles. On one side, according to Garrett Hardin, an ecologist at the University of California at Santa Barbara, are the Cassandras, who believe that continued population growth at the current rate will inevitably lead to catastrophe. On the other are the Pollyannas, who believe that humanity faces problems but has a good shot at coming out okay in the end. Cassandras, who tend to be biologists, look at each new birth as the arrival on the planet of another hungry mouth. Pollyannas, who tend to be economists, point out that along with each new mouth comes a pair of hands. Biologist or economist—is either one right? It is hard to think of a question more fundamental to our crowded world.

Cassandras and Pollyannas have spoken up throughout history. Philosophers in ancient China fretted about the need to shift the masses to underpopulated areas; meanwhile, in the Mideast, the Bible urged humanity to be fruitful and multiply. Plato said that cities with more than 5,040 landholders were too large; Martin Luther believed that it was impossible to breed too much, because God would always provide. And so on.

Early economists tended to be Pollyannas. People, they thought, are a resource—“the chiefest, most fundamental, and precious commodity" on earth, as William Petyt put it in 1680. Without a healthy population base, societies cannot afford to have their members specialize. In small villages almost everyone is involved with producing food; only as numbers grow can communities afford luxuries like surgeons, scientists, and stand-up comedians. The same increase lowers the cost of labor, and hence the cost of production—a notion that led at least one Enlightenment-era writer, J. F. Melon, to endorse slavery as an excellent source of a cheap work force.

As proof of their theory, seventeenth-century Pollyannas pointed to the Netherlands, which was strong, prosperous, and thickly settled, and claimed that only such a populous place could be so rich. In contrast, the poor, sparsely inhabited British colonies in the New World were begging immigrants to come and swell the work force. One of the chief duties of a ruler, these savants thought, was to ensure population growth. A high birth rate, the scholar Bernard Mandeville wrote in 1732, is “the never-failing Nursery of Fleets and Armies.”

Mandeville wrote when the Industrial Revolution was beginning to foster widespread urban unemployment and European cities swarmed with beggars. Hit by one bad harvest after another, Britain tottered through a series of economic crises, which led to food shortages and poverty on a frightful scale. By 1803 local parishes were handing out relief to about one out of every seven people in England and Wales. In such a climate it is unsurprising that the most famous Cassandra of them all should appear: the Reverend Thomas Robert Malthus.

“Right from the publication of the Essay on Population to this day,” the great economic historian Joseph Schumpeter wrote in 1954, “Malthus has had the good fortune —for this is good fortune—to be the subject of equally unreasonable, contradictory appraisals.” John Maynard Keynes regarded Malthus as the “beginning of systematic economic thinking.” Percy Bysshe Shelley, on the other hand, derided him as “a eunuch and a tyrant.”John Stuart Mill viewed Malthus as a great thinker. To Karl Marx he was a “plagiarist” and a “shameless sycophant of the ruling classes.” “He was a benefactor of humanity,” Schumpeter wrote. “He was a fiend. He was a profound thinker. He was a dunce.”

The subject of the controversy was a shy, kindly fellow with a slight harelip. He was also the first person to hold a university position in economics—that is, the first professional economist—in Britain, and probably the world. Married late, he had few children, and he was never overburdened with money. He was impelled to write his treatise on population by a disagreement with his father, a well-heeled eccentric in the English style. The argument was over whether the human race could transform the world into a paradise. Malthus thought not, and said so at length—55,000 words, published as an unsigned broadside in 1798. Several longer, signed versions followed, as Malthus became more confident.

“The power of population,”Malthus proclaimed, “is indefinitely greater than the power in the earth to produce subsistence for man.” In modern textbooks this notion is often explained with a graph. One line on the graph represents the land’s capacity to produce food; it slowly rises from left to right as people clear more land and learn to farm more efficiently. Another line starts out low, quickly climbs to meet the first, and then soars above it; that line represents human population. Eventually the gap between the two lines cannot be bridged and the Horsemen of the Apocalypse pay a call. Others had anticipated this idea. Giovanni Botero, an Italian scholar, described the basic relationship of population and resources in 1589, two centuries before Malthus. But few read Malthus’s predecessors, and nobody today seems inclined to replace the term “Malthusian" with “Boterian.”

The Essay was a jolt. Simple and remorselessly logical, blessed with a perverse emotional appeal, it seemed to overturn centuries of Pollyanna-dom at a stroke. Forget Utopia, Malthus said. Humanity is doomed to exist, now and forever, at the edge of starvation. Forget charity, too: helping the poor only leads to more babies, which in turn produces increased hardship down the road. Little wonder that the essayist Thomas Carlyle found this theory so gloomy that he coined the phrase “dismal science” to describe it. Others were more vituperative, especially those who thought that the Essay implied that God would not provide for His children. “Is there no law in this kingdom for punishing a man for publishing a libel against the Almighty himself?” demanded one anonymous feuilleton. In all the tumult hardly anyone took the trouble to note that logical counterarguments were available.

The most important derived from the work of MarieJean-Antoine-Nicolas Caritat, Marquis de Condorcet, a French philosophe who is best known for his worship of Reason. Four years before Malthus, Condorcet observed that France was finite, the potential supply of French infinite. Unlike Malthus, though, Condorcet believed that technology could solve the problem. When hunger threatens, he wrote, “new instruments, machines, and looms” will continue to appear, and “a very small amount of ground will be able to produce a great quantity of supplies.” Society changes so fast, in other words, that Malthusian scenarios are useless. Given the level of productivity of our distant ancestors, in other words, we should already have run out of food. But we know more than they, and are more prosperous, despite our greater numbers.

Malthus and Condorcet fixed the two extremes of a quarrel that endures today. The language has changed, to be sure. Modern Cassandras speak of “ecology,” a concept that did not exist in Malthus’s day, and worry about exceeding the world’s “carrying capacity,” the ecological ceiling beyond which the land cannot support life. Having seen the abrupt collapses that occur when populations of squirrels, gypsy moths, or Lapland reindeer exceed local carrying capacities, they foresee the same fate awaiting another species: Homo sapiens. Pollyannas note that no such collapse has occurred in recorded history. Evoking the “demographic transition”—the observed propensity for families in prosperous societies to have fewer children— they say that continued economic growth can both feed the world’s billions and enrich the world enough to end the population boom. No! the Cassandras cry. Growth is the problem. We’re growing by 100 million people every year! We can’t keep doing that forever!

True, Pollyannas concede. If present-day trends continue for centuries, the earth will turn into a massive ball of human flesh. A few millennia more, Ansley Coale, of Princeton, calculates, and that ball of flesh will be expanding outward at the speed of light. But he sees little point in the exercise of projecting lines on a graph out to their absurdly horrible conclusion. “If you had asked someone in 1890 about today’s population,” Coale explains, “he’d say, ‘There’s no way the United States can support two hundred and fifty million people. Where are they going to pasture all their horses?’”

Just as the doomsayers feared, the world’s population has risen by more than half since Paul Ehrlich wrote The Population Bomb. Twenty-five years ago 3.4 billion people lived on earth. Now the United Nations estimates that 5.3 billion do—the biggest, fastest increase in history. But food production increased faster still. According to the Food and Agricultural Organization of the UN, not only did farmers keep pace but per capita global food production actually rose more than 10 percent from 1968 to 1990. The number of chronically malnourished people fell by more than 16 percent. (All figures on global agriculture and population in the 1990s, including those in this article, mix empirical data with projections, because not enough time has elapsed to get hard numbers.)

“Much of the world is better fed than it was in 1950,” concedes Lester R. Brown, the president of the Worldwatch Institute, an environmental-research group in Washington, D.C. “But that period of improvement is ending rather abruptly.” Since 1984, he says, world grain production per capita has fallen one percent a year. In 1990, eighty-six nations grew less food per head than they had a decade before. Improvements are unlikely, in Brown’s view. Our past success has brought us alarmingly close to the ecological ceiling. “There’s a growing sense in the scientific community that it will be difficult to restore the rapid rise in agricultural yields we saw between 1950 and 1984,”he says. “In agriculturally advanced nations there just isn’t much more that farmers can do.” Meanwhile, the number of mouths keeps up its frantic rate of increase. “My sense,” Brown says, “is that we’re going to be in trouble on the food front before this decade is out.”

Social scientists disagree. An FAO study published in 1982 concluded that by using modern agricultural methods the Third World could support more than 30 billion people. Other technophiles see genetic engineering as a route to growth that is almost without end. Biologists greet such pronouncements with loud scoffs. One widely touted analysis by Ehrlich and others maintains that humanity already uses, destroys, or “co-opts” almost 40 percent of the potential output from terrestrial photosynthesis. Doubling the world’s population will reduce us to fighting with insects over the last scraps of grass.

Neither side seems willing to listen to the other; indeed, the two are barely on speaking terms. The economist Julian Simon, of the University of Maryland, asserts that there is no evidence that the increase in land use associated with rising population has led to any increase in extinction rates—despite hundreds of biological reports to the contrary. The biologist Edward O. Wilson, of Harvard University, argues that contemporary economics is “bankrupt” and does not accommodate environmental calculations—despite the existence of a literature on the subject dating back to the First World War. A National Academy of Sciences panel dominated by economists argues in 1986 that the problems of population growth have been exaggerated. Six years later the academy issues a statement, dominated by biologists, claiming that continued population growth will lead to a global environmental catastrophe that “science and technology may not be able to prevent.” “Told in an exchange of academic gossip that an eminent ecologist has had himself sterilized, an equally eminent demographer says, “That’s the best news I’ve heard all week!” Asking himself what “deep insights” professional demographers have contributed, Garrett Hardin answers, “None.”

The difference in the forecasts—prosperity or penury, boundless increase or zero-sum game, a triumphant world with 30 billion or a despairing one with 10—is so extreme that one is tempted to dismiss the whole contretemps as foolish. If the experts can’t even discuss the matter civilly, why should the average citizen try to figure it out? Ignoring the fracas might be the right thing to do if it weren’t about the future of the human race.

Two Nations

POPULATION QUESTIONS ARE FUZZY, EVEN AN APparently simple term like “overpopulation” is hard to define exactly. Part of the reason is that evaluating the consequences of rapid population growth falls in the odd academic space where ecology, economics, anthropology, and demography overlap. Another part of the reason is that attempts to isolate specific social or environmental consequences of rapid population growth tend to sink into ideological quicksand.

By way of example, consider two nations. One is about the size of Maryland and has a population of 7.2 million; the other is as big as Montana but has a population of 123.5 million. The first has a population density of 703 people per square mile, a lot by most standards; the second has a density of 860 per square mile, among the highest on the planet. Country No. 1 has tracts of untouched forest and reserves of gold, tin, tungsten, and natural gas. Country No. 2 has few natural resources and little arable land. Fife there is so crowded that the subways hire special guards to mash people onto the trains. Is it, therefore, overpopulated?

Most economists would say no. Country No. 2 is Japan. Paul Demeny, a demographer at the Population Council, in New York City, notes that Japan is where the Malthusian nightmare has come true. Population has long since overtaken agricultural capacity. “Japan would be in great trouble if it had to feed itself,” Demeny says. “They can’t eat VCRs. But they don’t worry, because they can exchange them for food.” Demeny is less sanguine about Country No. 1—Rwanda, the place with the highest fertility rate in the world. There, too, the production of food lags behind the production of people. But Rwanda, alas, has little to trade. “If something goes wrong,” Demeny says, “they will have to beg.”

Some economists might therefore attach to this crowded land the label “overpopulated.” Others, though, might say that Rwanda has not yet reached the kind of critical mass necessary to develop its rich natural endowment. Fewer than 200,000 souls inhabit Kigali, its capital and biggest city, hardly enough to be the hub of a modern nation. In this case, a cure for having too many children to feed might be to have more children—the approach embraced by the Rwandan government until 1983.

Rwanda’s leaders may well have been bowing to the popular will. By and large, people in the developing world have big families because they want them. “The notion that people desperately want to have fewer children but can’t quite figure out how to do it is a bit simple,”Demeny says. “If you picture an Indian who sees his children as capital because at the age of nine they can be sent to work in a carpet factory, his interest in family planning will not be keen.” If the hypothetical impoverished Indian father does not today desperately need the money that his children can earn, he will need it in his dotage. Offspring are the Social Security of traditional cultures everywhere, a form of savings that few can afford to forgo. In such cases the costs of big families (mass illiteracy, crowded hiring halls, overused public services) are spread across society, whereas the benefits (income, oldage insurance) are felt at home. Economists call such phenomena “market failure.” The outcome, entirely predictable, is a rapidly growing population.

Equally predictable is the proposed solution: bringing home the cost to those who experience the benefits. Enforcing child-labor and truancy laws, for example, drives up the price of raising children, and may improve their lives as well. Reducing price controls on grain raises farmers’ incomes, allowing them to hire adults rather than put their children to work. Increasing opportunities for women lets them choose between earning income and having children. In the short term such modifications can hurt. In the long term, Demeny believes, they are “a piece of social engineering that any modern society should aspire to.” Rwanda, like many poor countries, now has a population-control program. But pills and propaganda will be ineffective if having many children continues to be the rational choice of parents.

To ecologists, this seems like madness. Rational, indeed! More people in Rwanda would mean ransacking its remaining tropical forest—an abhorrent thought. The real problem is that Rwandans receive an insufficient share of the world’s feast. The West should help them rise as they are, by forgiving their debts, investing in their industries, providing technology, increasing foreign aid— and insisting that they cut birth rates. As for the claim that Japan is not overpopulated, the Japanese are shipping out their polluting industries to neighboring countries—the same countries, environmentalists charge, that they are denuding with rapacious logging. “If all nations held the same number of people per square kilometer,”Edward O. Wilson has written about Japan, “they would converge in quality of life to Bangladesh. . . ,” To argue that Tokyo is a model of populousness with prosperity is, Wilson thinks, “sophistic.”

Wait, one hears the economists cry, that’s not predation, that’s trade! Insisting on total self-sufficiency veers toward autarky. Japan logs other people’s forests because its own abundant forests are too mountainous to sustain a full program of—and wait a minute, haven’t we been here before? The competing statistics, the endless back-andforth argument? Isn’t there some better way to think about this?

Good News, Bad News

IN 1968, WHEN THE POPULATION HOME WAS FIRST PUBlished, the United Nations Population Division surveyed the world’s demographic prospects. Its researchers projected future trends in the world’s total fertility rate, a figure so common in demographic circles that it is often referred to, without definition, as the TFR. The TFR is the answer to the question “If women keep having babies at the present rate, how many will each have, on average, in her lifetime?” If a nation’s women have two children apiece, exactly replacing themselves and the fathers of their children, the TFR will be 2.0 and the population will eventually stop growing. (Actually, replacement level is around 2.1, because some children die.) In the United States the present TER is about 2.0, which means that, not counting immigration, the number of Americans will ultimately hit a plateau. (Immigration, of course, may alter this picture.) But the researchers in the division were not principally concerned with the United States. They were looking at poorer countries, and they didn’t like what they saw.

As is customary, the division published three sets of population projections: high, medium, and low, reflecting different assumptions behind them. The medium projection, usually what the demographer regards as the most likely alternative, was that the TFR for developing nations would fall 15 percent from 1965-1970 to 1980-1985. At the time, Ronald Freedman recalls, this view was regarded as optimistic. “There was a lot of skepticism that anything could happen,”he says. He was working on family-planning programs in Asia, and he received letters from colleagues telling him how hopeless the whole endeavor was.

Now a professor emeritus of sociology at the University of Michigan, Freedman is on the scientific advisory committee of Demographic and Health Surveys, a private organization in Columbia, Maryland, which is funded by the U.S. government to assess births and deaths in Third World nations. Its data, painstakingly gathered from surveys, are among the best available. From 1965-1970 to 1980—1985 fertility in poor countries dropped 30 percent, from a TFR of 6.0 to one of 4.2. In that period, Freedman and his colleague Ann K. Blanc have pointed out, the poor countries of the world moved almost halfway to a TFR of 2.1: replacement level. (By 1995, Blanc says, they might be two thirds of the way there.) If the decrease continues, it will surely be the most astonishing demographic shift in history. (The second most astonishing will be the rise that preceded it.) The world went halfway to replacement level in the twenty years from 1965 to 1985; arithmetic suggests that if this trend continues we will arrive at replacement level in the subsequent twenty years—that is, by 2005.

That’s the good news. The bad news is that since the late 1960s, 1.9 billion more people have arrived on the planet than have left. Even if future rates of fertility are the lowest in history, as is likely, the children of today’s children, and their children’s children, will keep replacing themselves, and the population will increase vastly. Nothing will stop that increase, not even AIDS. Pessimists estimate that by the end of the decade another 100 million people will be infected by HIV. Almost ten times that number will have been born. Barring unprecedented catastrophe, the year 2100 will see 10 to 12 billion people on the planet.

Nobody will have to wait that long to feel the consequences. In a few years today’s children will be clamoring to take their place in the adult world. Jobs, homes, cars, a few occasional treats—these are things they will want. And though economists are surely right when they say the lesson of history is that the great majority of these men and women will make their way, it is hard not to be awed by the magnitude of the task facing the global economy. A billion jobs. A billion homes. A billion cars. Billions and billions of occasional treats.

Trees and Soil

FEW PLACES IN THE United States better illustrate the unforeseen consequences of population growth than the lower valley of the Hudson River, which runs south from Albany to New York City. The river is wide and placid in appearance, and its banks sparkle with towns that were young when the nation was young. To the west rise the Catskills, blue at sunset and blanketed by trees. Interstate 87 makes a ribbon between the water and the mountains. A while ago I spent some time driving on that road, and down long miles of its length the forest stretched out so far and so dark and so empty that I imagined I was looking at the America of a hundred years ago, before there were millions of people like me around. How wonderful, I thought, that so close to Manhattan is a huge piece of real estate that we never trashed.

I was wrong. If I had traveled through the Hudson Valley at the end of the last century, I would have passed through an utterly different landscape. I would have been surrounded by small hardscrabble farms, fields of wheat and corn, and pastures ringed by stone walls. It might have looked picturesque—certainly guidebook writers of the day thought so. But I wouldn’t have seen many trees, because long before, almost every scrap of land that wasn’t vertical had been clear-cut or burned.

The forest was stripped to make way for agriculture and to supply New York’s army of charcoal-burners (who needed lumber to make charcoal), tanners (who extracted tannin from bark), and salt-makers (who used wood fuel to boil down seawater). Loggers played a role too: Albany, the northernmost deepwater port on the Hudson, was the biggest timber town in the nation and possibly the world. When the first Europeans came to New York, the region was almost entirely covered by trees; by the end of the nineteenth century less than a quarter of the state was wooded, and most of what was left had been picked through, or was inaccessible, or was being kept by farmers as private fuel reserves. During the epoch that I, swooping along the tarmac in my minivan, was nostalgically picturing as a paradise, newspaper editorials were warning that deforestation would drive the valley toward ecological disaster.

Since then the collapse of small farming has allowed millions of acres to return to nature. When New York State surveyed itself in 1875, the six counties that make up the lower Hudson Valley—Columbia, Dutchess, Greene, Orange, Putnam, and Ulster—contained 573,003 acres of timberland, covering about 21 percent of their total area. In 1980, the date of the most recent survey, trees covered almost 1.8 million acres, more than three times as much. (This is no scrubby growth, mind you. Michael Greason, an associate forester in the state’s Department of Environmental Conservation, calls today’s Hudson and Catskill forest a “beautiful, diverse ecosystem.”)

I was driving around the Hudson Valley partly because I was looking for a house in the country. My method of looking, insofar as one could call it a method, was to hunt in the counties with the lowest populations, figuring that they would be the least spoiled. I was trying to get away from people, and from the unpleasantness I associated with urban life. The more crowded an area, I thought, the more degraded its environment. I wanted natural beauty, and that meant “uninhabited.”

Learning some local history gave me pause. Back in 1875 my six counties had a collective population of 345,679. The U.S. Census says the figure for 1990 was 924,075. In other words, the number of people living there almost tripled in the same period that the local ecosystem climbed out of its sickbed and threw away its crutches. This wasn’t just some odd thing that happened in New York. As a whole, American forests are bigger and healthier than they were at the turn of the century, when the country’s population was below 100 million. Massachusetts and some other states have as many trees as they had in the days of Paul Revere. Nor was this growth restricted to North America: Europe’s forest resources increased by 25 or 30 percent from 1970 to 1990, a time in which its population grew from 462 million to 502 million. Presumably the forest figure would have been yet higher without the continent’s damaging acid rain.

People pollute. But more people does not always mean more pollution. Eco-critics can claim, with some justification, that the forests of the Hudson Valley recuperated because farmers abandoned them in order to wipe out the native grasslands of the Great Plains. But they can’t explain away all the good news. Salmon are reintroduced to the Thames. White-tailed deer, almost extinct in 1900, plague New England gardens. Air quality in Tokyo improves remarkably. Wild turkeys have a greater range than they did when they were first seen by white settlers. If all this occurred during the population boom, why the belief, now frequently voiced, that overpopulation will lead to an eco-catastrophe?

“You can look at Lake Erie or Detroit and see it’s gotten better,”says Dennis L. Meadows, the leader of the research group that produced The Limits to Growth. “But to leap from that to the conclusion that there has been overall improvement is to look at one person getting rich and say that everybody is better off.” Now at the helm of the Institute for Policy and Social Science Research at the University of New Hampshire, Meadows, with two co-authors, has recently published a sequel. Beyond the Limits, which is even more pessimistic than the first book. “When a rich country becomes concerned about environmental problems,”Meadows says, “then it can typically develop effective responses.”Lead additives in gasoline became a subject of American worries. The nation forced petroleum companies to phase out leaded gas, and lead levels diminished. Similar fears have led twenty-three industrialized countries since 1987 to halve the rate of release of the worst ozone-eating compounds. In Meadows’s view, rich countries have the wealth to buy their way out of many such difficulties. But other difficulties remain, and their number grows. Soil erodes; draining ruins wetlands; contaminants infiltrate groundwater; toxic wastes keep accumulating. The situation is much worse in poor countries that cannot pay to clean themselves up. Behind all the concerns is the specter of growing numbers, of insatiable human wants, of continually increasing demand. “We’re trying to sustain physical growth on a finite planet,” he says. “Growth will stop in our lifetime.” Meadows, who is fifty, confidently expects to see the end of population growth in his lifetime—probably through ecological breakdown.

Cassandras like Meadows, Ehrlich, and Lester Brown, of Worldwatch, regard land degradation as one of the worst and most obvious ecological consequences of crowding too many people into too little space. “Land degradation" is a catchall term covering such problems as wind and water erosion, soil pollution by urban wastes or pesticides, and the buildup of mineral salts caused by improper irrigation. The term may bring to mind newspaper photographs of faraway African husbandmen in terrain nibbled to exhaustion by cattle. But environmentalists say the problem is bigger than that—“virtually a worldwide epidemic,” in the words of Anne Ehrlich, a research associate at Stanford University, a veteran Cassandra, and the wife of Paul Ehrlich. The International Soil Reference and Information Centre (ISRIC), in the Netherlands, estimates that since 1945 Homo sapiens has degraded 17 percent of the world’s land, not counting wastelands like Antarctica and the Gobi Desert. Two thirds of the devastated area will require major restoration.

Every year, Brown warns, erosion steals 24 billion tons of soil from the world’s farmers—a figure that the ecology-minded cite as plain evidence that humanity is exceeding the carrying capacity of the planet. The economics-minded see rhetoric and hand-waving. “Those figures Lester Brown is going on are based on really wild assumptions,” says Pierre Crosson, a senior fellow at Resources for the Future, a nonprofit research group in Washington, D.C. “He’s taking poorly understood sedimentation figures from big river deltas and extrapolating them to get a figure for productivity loss for the whole world.” As for the ISRIC study, Crosson points out that it classifies most of Illinois, Iowa, Kansas, Nebraska, and the Dakotas as degraded enough to “greatly reduce” productivity. “The problem with this,”he says, “is that in those six states yields have risen steadily over the last forty years.”

The United States has the most carefully measured soil in the world. Every five years the U.S. Department of Agriculture evaluates the nation’s land, county by county, in terms of something called “the universal soil loss equation,” which assesses the soil movement in a given area. Because the equation measures movement rather than absolute disappearance, the results are hard to evaluate; they don’t distinguish between soil that ends up on the bottom of the ocean and soil that is merely shifted to a neighbor’s property, enriching yields there. (Sometimes the neighbors are far away: according to measurements by atmospheric scientists at the University of Virginia, more than 13 million tons of rich African soil are blown every year onto the Amazon forest floor.) In the 1980s three independent studies, one by Crosson, used the data to estimate actual soil loss. All concluded that the peril to U.S. agriculture from erosion is negligible. “The Soil Conservation Service is doing its job,” Crosson says.

It is hard to be as sanguine about the developing world. Sub-Saharan Africa, for instance, is often described as a place where overpopulation has led to a terrible destruction of land. The region has high birth rates; per capita food production has consistently fallen in the past ten years. Rainless years in the same period led to overgrazing, deforestation, wide-scale erosion, and the hunger shown in sad televised images. Civil strife and famine have driven at least two million people from their homes. The desert is said to be marching south at a rate of five to six miles a year, a scary prospect that Cassandras regard as dramatic evidence of Africa’s population quandary.

No one doubts that Africa is in a dire position, but the Pollyannas think that the problem is bad luck, bad weather, and bad planning. Traditionally, African villagers often held land in common, with access regulated by unwritten cultural rules. “In those circumstances,” Crosson says, “the people responsible for the management of the land take overuse into account, so they enforce rules of access that limit the use of the land.” When modern crops and agricultural techniques appear, the system comes apart, because yields shoot high enough to give people a greater incentive to cheat. If they break the rules, they can make a bundle and skip town with the profit; those who play fair are left with the ruins. (Garrett Hardin calls this the “tragedy of the commons.”) Population pressures exacerbate the problem, most economists concede, by shrinking everyone’s share of the common land. Add drought or ethnic conflict and the result is disaster. But, they say, African nations without drought or conflict have done increasingly well. Given half a chance, people in Africa, like people anyplace else, seem to make their own way.

The Cassandras base their case “on intuitively powerful hypotheses that slide over the need for empirical verification,”says Michael Mortimore, a senior research associate at Cambridge University, England. “Unfortunately, the only way to test them is to collect a large amount of empirical data.”Mortimore has spent years gathering information on farms in Nigeria and Kenya. His comparison of contemporary and thirteen-year-old dirt samples in Nigeria, one of Africa’s most heavily populated nations, shows that increasing population has, if anything, raised land productivity. In decades past, farmers could exhaust an area and then move on. Now rising numbers have made land more expensive, and people have greater incentives to take care of what they have. “You’re not going to pass on a desert to your children,” Mortimore says. Claiming that Africans are otherwise inclined is, to his mind, “straightforward cultural prejudice.” The agricultural systems that he studies are “economically, socially, and ecologically sustainable.” In Nigeria, he says, the 1992 harvest was the biggest in twenty years.

As for other parts of sub-Saharan Africa, no one denies the famine there. Yet recent independent studies have found no long-term environmental consequences of the recent and devastating drought; the southern border of the desert, one study shows, is in about the same place it was eighty years ago, suggesting that the desert expands and contracts with little regard for its human inhabitants. The drought may have led to temporary overuse of common property, economists concede, but the proper response would be to adjust land-use rules—change the zoning, so to speak—as societies did in other parts of Africa. That response’s alleged failure to occur in sub-Saharan Africa says more about the pervasive corruption, inefficiency, and civil turmoil there than about the inherent evils of breeding.

“You always can blame any particular difficulty on something that is not overpopulation,” Dennis Meadows says. “Nobody ever dies of overpopulation. They die of famine, pestilence, and war. There’s always some proximate cause.” Adjusting land-use rules is desirable in his view, but it does nothing to eliminate the fundamental problem. At bottom, more people means more resource use and more pollution and more loss of biodiversity, all of which must eventually stop. We can’t go on forever, because the world is finite. No matter how smart we are, Cassandras say, we can’t avoid being part of the web of life, governed by its laws. True enough, the Pollyannas say. But our part in that web is to be different. Other species die when they breed enough to wreck their environments, as they sometimes do. Human beings don’t wait to be overwhelmed. When problems arise, we solve them—that’s our nature. This argument makes Cassandras smite their collective brow and deride, as Ehrlich did recently, the “imbeciles running around today saying not to worry, that with the aid of science and technology we can take good care of many billions more.”

Thinking Differently

IN NATHAN KEYFTIZ’S VIEW, THE ARGUMENT AMOUNTS to a classic academic standoff. Keyfitz leads a group of demographers at the International Institute for Applied Systems Analysis (HASA), a research group in Austria, and is one of the few people I heard praised by both sides in the dispute. Keyfitz recalls attending a meeting at Brandeis University convened with the noble intention of reconciling biologists and economists. For three days speakers from each side stated their points of view, completely ignoring everything the other side had said. Then, apparently satisfied, everyone went home. “Here,” Keyfitz has written, “is a nightmare for democratic politics: what action to take on vital questions where the experts disagree violently.”

A first step away from the impasse, Keyfitz suggests, might be for each side to accept the validity of the other’s arguments, as long as they pertain to that side’s discipline. Give the biologists their due, and agree that an increased human presence poses a huge threat to the environment, even if some of the biologists’ claims are exaggerated. Then agree with economists that the problems are not due to population growth per se. Instead, population growth changes social and economic systems, which inevitably creates environmental problems: more food must be grown, so that once-adequate agricultural methods now overuse land.

But Keyfitz is hesitant to embrace the next step in the economists’ logic. “I think we all know the idea,” he says. “As you catch up with these problems one by one, you turn the power of science on them and produce solutions.” Sometimes the correction is expensive, Cassandras admit, but thoughtful government policies can minimize the pinch. Here we step outside the boundaries of economics into political science, into arguments nobody has promised to accept. The picture, Keyfitz says, has governments responding wisely—and, as everyone knows, they often don’t. Indeed, an outside observer might find it curious that economists—disdainful of government in other matters—exhibit such touching faith in the power of their elected representatives to resolve the troubles exacerbated by rising population.

Even if governments try to respond, they are often unable to anticipate the consequences of their actions. As a means of fostering international communication, Keyfitz says, “the worldwide air-transport network does nothing but good. But it’s responsible for the spread of AIDS. Otherwise it would be an unrecognized, unnamed disease in a corner of Africa.” With the instant contact possible today, a local problem became a global catastrophe.“You’d like more chance to breathe,” Keyfitz says. “I’m not saying that any of these problems are inherently unresolvable by themselves, but we wouldn’t be running so fast if the world had half its present population.”

As the human presence increasingly dominates the earth, new difficulties emerge at ever greater speed: The ozone layer. The exhaustion of fisheries. The greenhouse effect. The overuse of aquifers. The need to increase yields of tropical foodstuffs. Each must be evaluated, absorbed, treated, even as the next problem appears. The loss of biodiversity. The collapse of the infrastructure. The destruction of rain forests. And on and on. Maybe people can keep up; certainly Keyfitz’s colleagues, the computer modelers at HASA, think so. But in a world where every citizen is surrounded by examples of governmental incompetence, it is hard to imagine that nations will keep coming through, time after time. There’ll be so much juggling. So many things will have to be fixed all at once. Societies will find themselves in the position of the antic ninjas in video arcades, hordes of enemies to every side. Whack! Bam! Pow! Eventually, as any adolescent knows, the ninja slips up, and the game is over.

My Madonna Problem

FOR MANY YEARS I HAD AN OFFICE ON THE FOURteenth floor of a building in Manhattan, overlooking a busy avenue. During that time I never had air-conditioning, because it does something to the air that makes my nose run. In hot weather I opened the window. A breeze came in, reducing the temperature to a range I found tolerable. The problem was that it was hard to speak on the phone with the window open. People drove around the city with their car stereo systems cranked up to medically unsafe levels. Abrupt blasts of noise filled the room.

A debacle occurred when I interviewed Mario Cuomo, the governor of New York. Arranging the call involved considerable negotiation with his office in Albany. Two minutes into the conversation Madonna arrived. I had to shout over her moans. The governor did not immediately believe my explanation of the sound’s origin. The light changed; the noise went away. I asked him a question. Suddenly Madonna showed up again. I realized that she was circling the block, looking for a parking space. I slammed the window shut, raising the room’s temperature by ten degrees. The song was still devastatingly loud. The third time the song came round, I draped my jacket over the window. The fourth time, the governor hung up.

Soon after, I began looking for a house in the country.

The noise, and my response to it, illustrate what social scientists might regard as typical population-related feedback. Congestion grows in a city; it becomes impossible to avoid Madonna indoors; people move; the city becomes less congested. Or, perhaps, the city enforces noise ordinances. In either case the problem is resolved after temporary conflict.

“Temporary”—note the hedge word. The window of my old office looked out over the remains of the West Side Highway, part of which was closed as unsafe in the 1970s. I began using the office after a lengthy squabble had broken out over the best way to repair the road. Some wanted to do the job cheaply, shifting the money to mass transit; others said that the city needed the highway to revitalize its waterfront. Politicians, environmentalists, neighborhood groups, and construction unions attacked one another. Reconstructing the West Side Highway became a legal imbroglio of dizzying complexity. Charges and countercharges, suits and countersuits—I couldn’t begin to follow it. Meanwhile, huge rush-hour lines built up twice a day on the partially closed road. Not wanting to sit in traffic, people took the exit near my office and continued their journeys on my street. They’ve been doing that in one form or another for more than a decade— which is part of the reason there was so much congestion on the street, and part of the reason Madonna was in my office for so long.

Move to the country, buy extra-thick insulated windows—middle-class Americans like me are unlikely to face the extreme choices that will confront people in developing nations. As Meadows says, we will be able to buy our way out of some problems. But that does not mean that Americans will escape the repercussions of population growth. In 1990 the United States had 249 million inhabitants. Current Census Bureau projections foresee that births and immigration will drive that number to 345 million by 2030. Ninety-six million more Americans! Imagine everything that local, state, and federal governments will have to do to accommodate them. Think of all the thoughtful planning that will be required to make life pleasant. Whether it will happen “is an absolutely open question, in my judgment,” says Allen Kelley, an economist at Duke University. “We’re talking about political theory, and there just is no theory for this.”

The future is not completely opaque. Demographers know roughly where those 96 million new Americans will live, who they will be, and what they will do. The Census Bureau projects that the extra people will not distribute themselves in an even blanket over the country. About half will choose to live in just three states: California, Texas, and Florida. Not one of these can absorb its share easily. California has too little water, Texas an unsteady economy, Florida a particularly troubled set of ecosystems. All three will also need many new roads, bridges, sewers, and schools—an expensive proposition.

Relatively few of the newcomers will be white. By 2030 about 40 percent of Americans will have ancestral roots in Africa, Asia, or Latin America. Few would disagree that people of color have long been at the bottom of the American pyramid. If that continues, many of the 96 million will be poor, and in the twenty-first century a bigger percentage of the U.S. population will be below the poverty level than is now. If that does not continue, white Americans will for the first time face nonwhite power centers. California, Texas, and Florida will have three of the four biggest voting blocs in the House of Representatives (the fourth will be New York’s). All three could be dominated by Hispanics and African-Americans. If history is any guide, either alternative will put white Americans’ moral grace sorely to the test.

The United States has a long border with Mexico, and thousands of miles of coastline. Migrants want to come in, and Americans seem increasingly diffident about putting out the welcome mat. (In 1991 Argentina’s president publicly toyed with the idea of resettling skilled refugees at a price of about $50,000 a head.) Meanwhile, rising numbers will thrust together the blacks, whites, yellows, browns, and reds who are already here in ways they have not been before. Political turmoil is increasing in Europe—especially in France and Germany—as migrants from Africa, the Middle East, and the former Soviet bloc demand a piece of the better life. Population growth did not cause ethnic conflicts, but it could sharpen them.

At the same time, the United States will have to address its age shift. Census Bureau projections tell a sobering story. By 2030, one out of five Americans will be sixty-five or older. The ratio of elderly people to people of working age will have tripled since 1950, meaning that, on average, workers will have to support three times as many older people. (The figure may be offset somewhat by the smaller number of children there will be to support. But the problem will be amplified by the growing number of people in their sixties and seventies who will be taking care of still more elderly people, in their eighties and nineties.) Workers, meanwhile, will be facing gloomier prospects. Nowadays fewer older people are alive than younger people, which means that there is an approximate match between the small number of older workers and the small number of important jobs. As the population ages, this will change. “In a stationary population,” Ansley Coale, the Princeton demographer, has written, “there would no longer be a reasonable expectation of advancement as a person moves through life.” More and more people will find themselves trapped in dead-end jobs. In some ways, Coale suggests, we may end up looking back with envy at the days of rapid population growth.

People will have to deal with the frustration—at the same time that they seek politicians able to resolve all the other problems. An optimist can say that the American people are kind, clever, and adaptable. An optimist can say that Americans can resolve the difficulties described, and the others these will inspire. But even an optimist must conclude that the government will have its hands full, and might well wonder what it will be like to live in a future America that must balance so much so artfully. My guess is that it will be something like living in New York City today.

Because I had nothing else to do, I walked along the last remaining section of the West Side Highway one recent Friday afternoon—a masochistic act. The road is officially under construction, and so its shoulders have not been cleaned up. Heaps of trash lie in windblown aggregations. The walls are gray and peeling. Cars move slowly and impatiently, in billows of exhaust. It is like an evocation of an unpleasant future. New York City took a hit in the recession, and the familiar assortment of urban evils got worse. Unemployment and crack use went up; real estate values, tax revenues, and bond ratings went down. The city fabric sprang a hundred big leaks. Like so many Dutch boys, the city fathers raced to plug them. Meanwhile, a thousand interest groups scrabbled to protect themselves. Understandably, fixing the highway seems not to have assumed pressing importance.

That day on the West Side Highway, I heard many radios played at high volume. I could see the point. License plates came from Connecticut, New Jersey, and Pennsylvania; drivers were commuting for hours to sit in traffic. Only part of their daily grind was due to the sheer size of New York; traffic jams afflict much smaller cities. But a three-hour commute is what some architects call a “disamenity.” The waiting, the ugly walls, the blaring horns, the inability to get away from it all: these are the disamenities of overpopulation in rich societies. None is directly attributable to population growth. Each is an emblem of bureaucratic overload—overload caused by the hundred predicaments that population growth aggravates. The city could have fixed the West Side Highway long ago. So could the state, or the federal government. But they didn’t. There are too many other, bigger concerns, and there will be for a long time. My Madonna problem is not going to vanish.

Population growth forces nations to confront problems that they could finesse in less crowded times. The inefficiencies of New York’s highways surely mattered less when the metropolitan area held eight million people rather than fifteen. Governments may, as economists hope, avoid the major, life-threatening disasters. “Even Congress isn’t stupid enough to avoid dealing with the ozone layer,” one economist told me. Americans may create a society that can hold an older, darker-colored population. But while they are doing that, the disamenities accrue, making the future a grayer, grimier place. Per capita GNP may go up and up, but life will be less pleasant. How much less pleasant? The answer depends on the strength of the citizenry’s desire to have a government that works much more flexibly and wisely than government does now. New Yorkers to date have shown little such inclination.

Down by Wall Street the West Side Highway has been demolished. The reconstructed roadway passes a few blocks to the west of the building where I saw those people on the gurneys. My guess is that most of its inhabitants—the real ones, I mean—have moved on. More have moved in, though. We’re marching into the future together. Curtains are visible from the highway. There’s some lawn furniture on the roof. It makes me wonder who owns it, and what they do, and whether, like me, they have children.