Overpopulation: Where Malthus Went Wrong

John S. Morton, Jane S. Shaw
and Richard L. Stroup

Fear of population growth has been with us for a long time-at least since Thomas Malthus predicted in 1798 that population would grow at a geometric rate while food production increased at an arithmetic rate. Unless birth rates were checked or wars and disease raised the death rate, he said, England and the rest of world would face inevitable famine and a subsistence standard of living.

Malthus' Error
Malthus' predictions never came true. He would be surprised that almost 200 years later the world's population is much larger and, for the most part, better off. There have been famines, but they have had more to do with local conditions and politics than with the inability of Earth's resources to support the population. Malthus did not foresee that pesticides, machines, refrigeration, and other technical advances would make it possible to feed enormous numbers of people very well. Except in cases influenced by war and political repression, starvation is rarely a widespread problem these days; in advanced nations, obesity is a far greater threat to health than starvation. Life expectancy in the developed countries has nearly doubled, from 40 years in the 18th century to well over 70 years now.

Modern Malthusians
Was Malthus fundamentally wrong? Or was he right before his time? Today an active debate is going on between the "apocalyptics" and the "cornucopians." Apocalyptics are modern-day Malthusians who believe that technical innovation has only temporarily stayed the overpopulation catastrophe. Cornucopians are optimists who believe that progress will continue.
Paul Ehrlich, a famous apocalyptic, predicted in 1968 that "massive famines" were likely in the 1970s. That did not happen, but the alarm continues. "Scores of countries with rapid population growth-among them Iran, Egypt, Ethiopia, Nigeria, and Mexico-will find themselves facing huge food deficits in the years ahead," said Lester Brown in the Worldwatch Institute's 1995 report, State of the World.1

The apocalyptics have a point. Population growth has accelerated during the twentieth century. Between 1850 and 1900, world population grew at an annual rate of 0.6 percent. By 1970, it was growing at a rate of 2.06 percent, far faster than at any time in history.

The Cornucopians' Retort
But the cornucopians have the experience of recent decades, even centuries, on their side. Every projection of inevitable or global doom has, up to now, been proven wrong.
Massive famines that result in widespread starvation today typically grow out of political conflict. Ethiopia, for example, has some of the best farmland in Africa, but political disruptions have thrown food production there into a tailspin.

Furthermore, it is unlikely that growth in world population will continue at the rates we have seen in our lifetime. Some demographers now surmise that the rapid population growth in the twentieth century is a unique phenomenon reflecting, in part, our enormous success in reducing mortality rates.

Lower birth rates have lagged behind the dramatic declines in mortality rates, but now birth rates are going down, too. Between 1970 and 1990, the population growth rate declined from a frightening 2.06 percent to 1.73 percent. In Thailand, the fertility rate fell from 4.6 children per woman in 1975 to 2.3 children in 1987; in Colombia, it fell from 4.7 in 1976 to 2.8 in 1990.2 Declines like this are widespread in the developing world. And in the industrialized countries, at current birth rates, the population is barely replacing itself.

The explanation for these declines is complex and not fully understood. But low birth rates in the industrial world seem pretty clearly linked to economic growth.

In developing countries, the benefits of having children are much greater than the costs to parents. The costs of rearing children are low, since families do not invest heavily in children's schooling or health care, and children can often contribute income to the family while they are young. Mothers do not have many opportunities to earn income outside the home, so the opportunity cost of staying home is low. In old age, parents are often dependent on their children to support them because there is no effective social security system and old people often lack adequate savings or retirement income. As a result, parents regard large families as a means of guaranteeing support and security in their old age.

In the industrialized world, however, expectations for children's achievements are much higher. Families invest heavily in their children's education, and their children may not earn any income for decades. Furthermore, most women have attained an education that opens up opportunities for earning income outside the home. Staying home with many children therefore means giving up substantial income. In other words, in the more specialized world of the industrial West, rearing children is costly to parents. As you would expect, then, there is a trend away from having many children in the Western countries.

This shift to lower birth rates as nations develop market economies, and income rises, is called the "Demographic Transition." As economic growth transforms the developing world, a similar transition is also likely to occur there. Provided that opportunities for women's education continue to open up and investment in children's education proves valuable, a decline in the birth rate is to be expected.

Will Progress Continue?
In their argument with the apocalyptics, then, the cornucopians seem to have the edge. But the cornucopians are wrong if they assume that the progress that has occurred in the past will inevitably continue. In assessing the rate of population growth and its impact, we must remember that a society's institutions drive both. Those institutions may be more fragile than some cornucopians think.
One of those institutions is private property rights, which provide the basis for trade and specialization. Where private property rights are the norm, as they are in industrial nations most of the time, high population densities can easily be supported. Even a nation as densely populated as the Netherlands-which has 964 people per square mile, compared with India's 766 people per square mile-has no trouble feeding itself.3 In fact, the Netherlands is an agricultural exporter. Gwartney, Lawson, and Block, in Economic Freedom of the World: 1975-1995, have demonstrated that the freedom to own and trade property rights strongly influences both the level and growth of prosperity among nations.4 (See also the Economist article, "Of Liberty, and Prosperity.")5

The Importance of Private Property Rights and Markets
Societies based on private property rights and markets can support many people because private property rights allow for and reward innovation, while penalizing wastefulness. Resource users must pay for what they use, so they have an incentive to reduce their costs and increase the attractiveness of their products to increase their sales. The result is not simply more production but also savings in resources.
Many people today live in countries where government economic policies discourage the careful use of resources and hamper the specialization that makes it possible to support high population densities without ruining the environment. Where private property is not protected, waste is often not penalized, and people are not allowed to benefit from what they produce (in other words, to reap what they sow). In these situations, population expansion makes it hard for people to live decently.

If those countries could move in locally acceptable ways to adopt and protect the institution of private property and other market institutions, the picture would be far brighter, as it is in Singapore and Hong Kong, for example. These are tiny places with minimal natural resources, yet they support large populations. Indeed, in India, where the government recently loosened its control of property, food production has soared and the famines of the past have become only a memory.

In the debate between the apocalyptics and the cornucopians, most economists favor the cornucopians. Greater population does not have to be a problem. But the apocalyptics have a warning that we should heed: If the institutions that shape the economy are wrong, we may have a population crisis after all. Currently rapid population growth is concentrated in exactly those economies where institutions are only slowly and fitfully moving in a direction which will help them escape Malthusian poverty.

Researching Population Growth: A Teaching Example
The idea that population growth harms the environment has become one of today's prevailing assumptions. Therefore, the causes and effects of population growth offer an excellent opportunity for social studies teachers to illustrate that a hypothesis must be tested through research. In addition, analyzing population growth helps students to understand how economic theory guides research. Theory helps researchers make sense out of observations. According to Paul Heyne, "those who try to reason about complex economic interrelationships without theory usually manage only to reason with very poor theory."6
A key tenet of economic theory is that people choose for good reasons. In other words, people consciously or unconsciously weigh the relative benefits and costs of their alternative choices and choose the alternative that provides them the greatest net benefits.

The teaching activity described below is highly structured and is designed to help students gain insights into the causes and effects of population growth. Brief suggestions for other student research activities follow this initial activity.7

The Costs and Benefits of Having Children
A. Explain to the class that the purpose of this lesson is to examine the costs and benefits of having children. Ask the students what they think it costs their parents to raise them. Entertain all kinds of answers; make a list on the chalkboard.
B. Tell students that their suggestions probably ignore an important cost-the opportunity cost of raising children. Parents have limited amounts of time and income. The opportunity cost of time spent with children might be income not earned at work, meals not prepared, fun not had with adult friends, or household work not done. One or both of the parents in any given family may have declined to accept a new job because they were too busy raising a child. One parent in any given family may not work or may have taken leave from work in order to raise a child.
C. Ask students how their parents benefit from raising them. Entertain several answers, but emphasize nonmonetary benefits such as enjoying children's company, being proud of their achievements, and children keeping the parents feeling young.
D. Tell the students that they will do research to solve an economic mystery. The mystery is: "Why do people in poor countries have more children than people in rich countries?" They should keep this mystery in mind as they do their research.
E. Give each student a copy of Chart 1 and explain the statistics on it.
F. Divide students into groups of three and direct them to answer the questions in Part 1 of the activity. They probably will need help getting started.
G. Discuss the answers to the questions in Part 1 of the activity. These are as follows:
1. Canada, Hong Kong, Japan, Switzerland, and United States.
2. 3140.0 people per square mile.
3. 12.8 per 1000 people.
4. 6.2 per 1000 live births.
5. 81.2 years.
6. Afghanistan, Bangladesh, Ethiopia, Haiti, and Somalia.
7. 617.4 people per square mile.
8. 42.0 per 1000 people.
9. 121.0 per 1000 live births.
10. 51.0 years.

H.Now tell the students to return to their groups and answer the questions in Part 2. Assign each group to report to the class and then have the class discuss each question. The answers are as follows:
1. Poor nations have higher birth rates than rich nations. In poor nations, the benefits of having children are greater, while the opportunity costs of raising children are lower.
2. Birth rates decline as nations grow wealthier. Strong economic growth, which is characteristic of market economies, is therefore one of the most effective methods of population control.
3. Rich nations. There appears to be a lot of land left for future population expansion. Although many rich nations have high population densities, they also have the wealth to fund programs that improve the environment.
4. It is much better in rich countries. Rich countries have lower infant mortality rates and longer life expectancies.
5. Hong Kong has a market economy, which creates incentives that differ from those in the command economy in China.
6. It rejects the hypothesis. As people become more prosperous, the rate of population growth slows. In addition, citizens of countries with high population densities have higher standards of living than citizens of countries having lower population densities.
Now come back to the mystery, "Why do people in poor countries have more children than people in rich countries?" People consider costs and benefits when they make choices. As economies grow, the opportunity costs of having more children increase and the monetary benefits decrease. Therefore, economic growth may be the most effective population control measure. To help students solve this mystery, remind them of the discussion at the beginning of the lesson.

Further Research
One problem with the above lesson is that only 20 nations were analyzed. Those nations could have been chosen to make a point, and they may not reflect the entire world picture. Therefore, encourage students to do their own research. The information in Chart 1 is available from traditional printed sources such as Rand McNally's World Facts and Maps, and The World Almanac and Book of Facts. These publications are updated annually. Even more recent information is available on the Internet. Two good sources are the CIA Web site at http://www.odci.gov/CIA as well as the Penn World Tables home page at http://cansim.epas.utronto.ca:5680/pwt/
pwt.html. Here are some research questions that could be analyzed using data from these sources.

1.Do developed or developing countries have higher birth rates? Why? Develop a hypothesis to explain the results of your research.
2.How does the population density of rich Asian countries compare with the population density of poor Asian countries? How does your answer relate to worries that the world is running out of room?

1.Lester R. Brown, "Nature's Limits." In State of the World 1995, edited by L. R. Brown (New York: Norton, 1995): 20.
2.Bryant Robey, Shea O. Rutstein and Leo Morris, "The Fertility Decline in Developing Countries" Scientific American (Dec. 1993): 61.
3.World Almanac and Book of Facts 1996 (Mahwah, NJ: World Almanac Books, 1995): 772-801.
4.James Gwartney, Robert Lawson and Walter Block, Economic Freedom of the World: 1975-1995 (Washington, D.C.: The Cato Institute, 1996).
5."Of Liberty, and Prosperity" The Economist (Jan. 13-19, 1996): 21-23.
6.Paul Heyne, The Economic Way of Thinking. Seventh edition (New York: Macmillan, 1994).
7.Mark C. Schug, John S. Morton and Donald R. Wentworth, Economics and the Environment: Eco Detectives. (New York: National Council on Economic Education, 1997).
John S. Morton is President of the Arizona Council on Economic Education. Jane S. Shaw is Senior Associate at the Political Economy Research Center (PERC), Bozeman, Montana. Richard L. Stroup is Professor of Economics at Montana State University, Bozeman, Montana.

Chart 1
A Tale of 20 Nations
Examine the statistics in the table below. Answer the questions in Parts 1 and 2 of the activity.
Hong Kong*14,316$21,32612806
United Kingdom619$16,90013807
United States72$24,70015808
*Hong Kong is now part of China.
Source: World Almanac, 1996; for Hong Kong, Rand McNally's World Facts and Maps, 1996 ed.

Part 1: Analyzing Statistics
1. Which five nations have the highest per capita GDP? (We will consider these nations rich.)
2. What is the average population density per square mile of these five rich nations? (Hint: Add up these five nations' population per square mile and divide by five.)
3. What is the average birth rate per 1000 people for these five rich nations? (Hint: Add up these five nations' births per 1000 and divide by five.)
4. What is the average infant mortality rate per 1000 live births for these five rich nations? (Hint: Add up these five nations' infant mortality rates and divide by five.)
5. What is the average female life expectancy for these five rich nations? (You shouldn't need a hint by now.)
6. Which five nations have the lowest per capita GDP? (We will consider these nations poor.)
7. What is the average population density per square mile of these five poor nations?
8. What is the average birth rate per 1000 people for these five poor nations?
9. What is the average infant mortality rate per 1000 live births for these five poor nations?
10. What is the average female life expectancy for these five poor nations?

Part 2: Drawing Conclusions
1. Do rich nations or poor nations have a higher average birth rate? Why do you think this is so?
2. What will probably happen to population growth as nations become richer?
3. Do rich nations or poor nations have a higher average population density per square mile? What does this indicate about the capacity of the world's resources to support more people?
4. How does the quality of life in poor nations compare with the quality of life in rich nations? (Use statistics from the chart, and inferences from those statistics, to support your answer.)
5. Population density in Hong Kong is much greater than in China. Then why is Hong Kong so much wealthier than China?
6. Does your research make you inclined to support or reject the hypothesis that future population growth threatens the environment and will result in starvation for many people and lower living standards for most people?