At the end of each day, the world has more than 200,000 more mouths to feed than it had the day before; at the end of each week, it has 1.5 million more mouths to feed; and at the close of each year, it has an additional 75 million mouths to feed. In the world’s poorest countries, where population growth is most rapid, the lives of hundreds of millions of people are constantly plagued by hunger and by diseases aggravated by malnutrition. Humankind, entering the 21st century, now numbers well over 6 billion and is caught in an ambush of its own making. Economists call it the “Malthusian trap” after the man, Thomas Robert Malthus, who stated our grim biological predicament most forcefully: Population growth tends to outstrip the supply of food.
Malthus was born in a country house near the town of Dorking, England, the son of a gentleman who prided himself on his advanced ideas and who was an admirer and friend of both Hume and Rousseau. Young Robert (he was never called Thomas) was at first privately educated. In 1784, he went to Jesus College, Cambridge, where he graduated creditably as Ninth Wrangler (an honors degree in mathematics) in 1788. In that same year, he took holy orders and later was appointed to a rectory. In livelihood, however, he was less a “parson,” as his detractors have often chosen to call him, than a college professor, for in 1805 he became the first professor of political economy in the English-speaking world at the new East India College in Hertfordshire, a post he held until his death in 1834. He published his controversial book, An Essay on the Principle of Population as It Affects the Future Improvement of Society, anonymously in London in 1798 and brought out a greatly enlarged edition in 1803.
Eighteenth-century thinkers had tended to view population growth as a mark of social well-being; an increase in people was generally taken to imply an increase in wealth. Malthus saw it differently. He began with the awesome redundancy of nature: “Through the animal and vegetable kingdoms,” he wrote, “nature has scattered the seeds of life abroad with the most profuse and liberal hand.” On the other hand, he asserted that nature “has been comparatively sparing in the room and the nourishment necessary to rear them.” It follows that the tendency of populations to multiply, if unchecked by other means, will eventually be checked by starvation; the number of people will simply (and, of course, only temporarily) outstrip the supply of food. This is the most brutal and final of “positive” checks to population growth.
As a former mathematics student, Malthus could not resist a mathematical illustration. He wrote that population can increase geometrically, whereas agricultural production can increase only arithmetically. So, while the population grows “in the ratio of 1, 2,4, 8,16,32,64…,” subsistence will increase only as 1,2, 3, 4, 5, 6, 7, and so on. That was a persuasive argument, although only the first part of it was true on its face; the reproductive potential of any plant or animal species verifies it. Both Charles Darwin and Alfred Russel Wallace, impressed with Malthus’s argument, found in it the key to the theory of natural selection. Darwin, 2 years after his round-the-world voyage on the Beagle and puzzling over the origin of species, happened to read Malthus’s essay (“for amusement”) and was immediately struck with its relevance to his problem. “A struggle for existence,” Darwin wrote in On the Origin of Species, “inevitably follows from the high rate at which all organic beings tend to increase….It is the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms.” Darwin reasoned that if more organisms are born than can possibly survive, it will be the best adapted or “fittest” variants that do survive, and with enough new variants over a long period of time, new species could evolve. The second part of Malthus’s proposition was problematical because Malthus, depending on his observations of the agricultural practices of the late 18th century, did not foresee the increased food production that would follow the industrial revolution. For more than a century after Malthus’s death, food supplies increased far more rapidly than he had predicted. But during the post-World War II period, when antibiotics and other medical and health improvements caused huge population increases, food supplies would again be inadequate to provide for the world’s hungry and malnourished. No doubt, Malthus would now feel vindicated by history.
The earnest effort of many governments to encourage birth control, together with a new self-reliance among better-educated women in the developing countries (and thus their acceptance of family planning), has helped to bring total world growth rates down somewhat during recent years. But birth control information and assistance are not available everywhere, and this is one reason why global growth rates are still ominously elevated. Realistic mid-range projections show world population increasing from 6 billion in the year 2000 to 9 billion by 2050—a 50% increase in only 50 years. Such rapid growth, so long continued, is causing human demands to overshoot not only the world’s finite resource base but also its environmental carrying capacity, with potentially tragic results for our own generation as well as future generations.
Environmental overload is already causing dramatic losses of much-needed cropland due to salination, waterlogging, and erosion as well as to urban sprawl, road building, and other effects of larger populations. Rangeland and fisheries are also being exploited beyond their capacity for recovery. Meanwhile, 1 billion of the world’s 6 billion people are chronically malnourished, and in densely populated countries such as India, Bangladesh, Pakistan, Ethiopia, and Nigeria, where half of the children are already undernourished, hunger continues to increase as populations grow. Water shortages are a part of the population-food equation that could hardly have seemed troubling to Malthus, living in a country of plentiful rainfall. But freshwater shortages may well be the most severe threat of all, not only to the human need for potable water but also to the needs of industry and agriculture. As populations grow, the demands for freshwater supplies of all sorts—surface water, ground-water, reclaimed water—are increasing. Meanwhile, many ancient aquifers (which are mainly “fossil water” deposited over many centuries) are being over pumped for irrigation and are in danger of nearly total depletion in the foreseeable future, threatening food production on irrigated lands. And irrigation itself, on which so much of world food production depends, can have deleterious aftereffects that eventually make the soil virtually worthless for agriculture.
Population growth also causes energy-related problems such as air pollution, global warming, depletion of fossil fuel supplies, and destruction of the ozone layer. These detrimental effects are due partly to voracious fuel consumption in the industrialized societies, but they are also due to the huge increase in energy demands required to double or triple food supplies during this century so as to feed the world’s burgeoning population more equitably and adequately. This disparity between increasing energy demands and diminishing traditional energy supplies has prompted a close look at newer or alternative (and less polluting) energy sources, including wind, solar, hydro, geothermal, and hydrogen power. All of these, however, are still in the early stages of commercial development.
Overpopulation also burdens and stresses the environment. It is increasingly clear even to casual observers that dense populations degrade the long-term carrying capacity of the earth. The wealth of the earth is far less a matter of gold and silver than of fertile soil, forests, fisheries, fresh water, and clean air; these are the assets that sustain our lives and undergird our civilization. But that fundamental wealth is being depleted by a global population that is too numerous and too wasteful.
Various kinds of social disruption are also caused by population growth. Disputes over inadequate supplies of food, water, and other resources can destabilize governments, cause civil strife, and degenerate into social chaos. Meanwhile, preexisting religious or ethnic conflicts can be exacerbated by ongoing demographic pressures, causing riots, massacres, and “ethnic cleansing.” They may also spur large-scale emigration to neighboring countries that are often hostile to such massive immigration. Rapidly growing populations can also breed international conflicts over shared or common resources such as water, and these conflicts have implications for other nations, often far removed from the locations of the struggles. In 2002, Thoraya Obaid, head of the United Nations Population Fund, pointed out that rapidly increasing populations in the Middle East have resulted in very high proportions of young people there, and many of them are radicalized by “a growing sense of inequality and injustice” that, she warned, leads to extremism and terrorism. “There is no doubt,” she said, “that demographics and population are linked to political instability,” and she called for improved family planning services, health services, and education.
From the very beginning, Malthus’s message was greeted with widespread hostility, and that antagonism has continued to the present day. Criticisms now come chiefly from those holding left-leaning social ideas or right-leaning capitalist doctrines or from those with religious objections to birth control. The critics operate on the assumption that despite the population explosion of the past half century, all is well nonetheless. They simply assert that there is no population problem, that overpopulation does not cause hunger, that all of the talk about overpopulation is only a mask to conceal capitalist—or socialist— failures, and that the world and its natural resources are, for practical purposes, infinite. However, the desperate conditions in much of the Third World today refute these ideas.
Another obstacle to sensible population limitation is the hierarchy of the Roman Catholic Church, which condemns birth control, calling it “an offense against the law of God and of nature.” Most other religions disagree with this opinion, but the Catholic hierarchy, wielding the political power of large congregations, continues to oppose population limitation. Its influence is especially unfortunate in the United Nations, where for many years it has succeeded in weakening or preventing family planning programs despite the current suffering in the Third World and the severe hardships that continuing overpopulation will inevitably bring to people everywhere.
Complicating this picture is the Catholic hierarchy’s associating birth control with abortion so that U.N. population programs can be further undermined by the accusation that they promote abortion—even when that is not true and even though birth control has been shown to prevent large numbers of abortions. On the abortion issue, the Catholic hierarchy is joined in an unlikely alliance with certain American fundamentalist Protestant groups. Together, with their strong influence on conservative politicians, they have successfully pressured several administrations in Washington, D.C., to ignore the global population problem and to withhold family planning contributions to the United Nations. When Malthus died in 1834, the total population of the world barely exceeded 1 billion. If he were to return now in the 21st century, he would find a world population that is well over 6 billion. He would be surprised at that because he would find it hard to believe that food supplies had increased sufficiently to keep so many people alive. He would be far less surprised to hear that of those 6 billion people, 1 billion of them—as many as existed in total during his own time—are suffering from malnutrition and in danger of starvation. So, despite two centuries of progress in agricultural productivity, there is little in today’s world situation that would cause Malthus to change his mind. In many Third World countries, there is simply not enough locally grown food to nourish the population adequately, and food from foreign sources is increasingly expensive and unaf-fordable due largely to the high costs of oil and fertilizer. Meanwhile, the world population keeps growing by 75 million mouths per year. Because of rapid population growth, humans everywhere face a future of uncertainty and prodigious challenge. But the same man who anticipated our current predicament also prescribed the only tenable response to it. As Malthus wrote, “Sufficient yet remains to be done for mankind to animate us to the most unremitted exertion.”
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