Demographic Theories

Learning Outcomes

  • fDescribe demographic theories—Malthusian, cornucopian, zero population growth, and demographic transition theories

Demographic Theories

Sociologists have long looked at population issues as central to understanding human interactions. Understanding population growth gives us some insight on how many schools, homes, hospitals and even prisons we need to build, as well as other economic factors that impact societies. Below we will look at four theories about population that inform sociological thought: Malthusian, zero population growth, cornucopian, and demographic transition theories.

Malthusian Theory

Thomas Malthus (1766–1834) was an English clergyman who made dire predictions about earth’s ability to sustain its growing population. According to Malthusian theory, three factors would control human population that exceeded the earth’s carrying capacity, or how many people can live in a given area considering the amount of available resources. Malthus identified these factors as war, famine, and disease (Malthus 1798). He termed them “positive checks” because they increase mortality rates, thus keeping the population in check. They are countered by “preventive checks,” which also control the population but by reducing fertility rates; preventive checks include birth control and celibacy. Thinking practically, Malthus saw that people could produce only so much food in a given year, yet the population was increasing at an exponential rate. Eventually, he thought people would run out of food and begin to starve. They would go to war over increasingly scarce resources and reduce the population to a manageable level, and then the cycle would begin anew.

Watch It

Watch the following video about Malthus’ Essay on the Principle of Population to learn more about his theory.

Of course, this has not exactly happened. The human population has continued to grow well beyond Malthus’s predictions. So what happened? Why didn’t we die off? There are three reasons sociologists believe we are continuing to expand the population of our planet. First, technological increases in food production have increased both the amount and quality of calories we can produce per person. Second, human ingenuity has developed new medicine to curtail death from disease. Finally, the development and widespread use of contraception and other forms of family planning have decreased the speed at which our population increases. But what about the future? Some still believe Malthus was correct and that ample resources to support the earth’s population will soon run out.

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Zero Population Growth

A neo-Malthusian researcher named Paul Ehrlich brought Malthus’s predictions into the twentieth century. However, according to Ehrlich, it is the environment, not specifically the food supply, that will play a crucial role in the continued health of planet’s population (Ehrlich 1968). Ehrlich’s ideas suggest that the human population is moving rapidly toward complete environmental collapse, as privileged people use up or pollute a number of environmental resources such as water and air. He advocated for a goal of zero population growth (ZPG), in which the number of people entering a population through birth or immigration is equal to the number of people leaving it via death or emigration. While support for this concept is mixed, it is still considered a possible solution to global overpopulation.

Further Research

To learn more about population concerns, from the new-era ZPG advocates to the United Nations reports, check out Population Connection and the UN Populatin Division.

Cornucopian Theory

Of course, some theories are less focused on the pessimistic hypothesis that the world’s population will meet a detrimental challenge to sustaining itself. Cornucopian theory scoffs at the idea of humans wiping themselves out; it asserts that human ingenuity can resolve any environmental or social issues that develop. As an example, it points to the issue of food supply. If we need more food, the theory contends, agricultural scientists will figure out how to grow it, as they have already been doing for centuries. (A “cornucopia” is a horn-shaped container overflowing with sources of nourishment; it traditionally symbolizes abundance.) After all, in this perspective, human ingenuity has been up to the task for thousands of years and there is no reason for that pattern not to continue (Simon 1981).

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Demographic Transition Theory

Whether you believe that we are headed for environmental disaster and the end of human existence as we know it, or you think people will always adapt to changing circumstances, we can see clear patterns in population growth. Societies develop along a predictable continuum as they evolve from unindustrialized to postindustrial. Demographic transition theory (Caldwell and Caldwell 2006) suggests that future population growth will develop along a predictable four-stage (sometimes five-stage) model.

In Stage 1, birth, death, and infant mortality rates are all high, while life expectancy is short. An example of this stage is the 1800s in the United States. As countries begin to industrialize, they enter Stage 2, where birthrates are higher while infant mortality and the death rates drop. Life expectancy also increases. Afghanistan is currently in this stage. Stage 3 occurs once a society is thoroughly industrialized; birthrates decline, while life expectancy continues to increase. Death rates continue to decrease. Mexico’s population is at this stage. In the final phase, Stage 4, we see the postindustrial era of a society. Birth and death rates are low, people are healthier and live longer, and society enters a phase of population stability. Overall population may even decline. For example, Sweden is considered to be in Stage 4. Some scholars have added Stage 5, suggesting another stage when fertility either remains below replacement levels, or begins to rise slowly again.

The demographic transition in five stages. The graph shows how stage 1 has high birth and death rates, then in stage two the death rate falls rapidly while birth rates rise, causing a natural increase. This continues into Stage 3, then in stage 4, there are low birth rates and low death rates, and in stage 5 birth rates begin to slowly increase again.

Figure 1. This shows how the changes in birth and death rates affect total population during the demographic transition stages.

The United Nations Population Fund (2008) categorizes nations as high fertility, intermediate fertility, or low fertility. The United Nations (UN) anticipates the population growth will triple between 2011 and 2100 in high-fertility countries, which are currently concentrated in sub-Saharan Africa.

A graph projecting the growing population of Africa. It shows that in 1950, the population was around 200 million, and is expected to rise to over 4 billion by 2100.

Figure 2. Projected Population in Africa: This graph shows the population growth of countries located on the African continent, many of which have high fertility rates. (Graph courtesy of USAID)

For countries with intermediate fertility rates (the United States, India, and Mexico all fall into this category), growth is expected to be about 26 percent.

A bar graph predicting the growing population of the United States. It shows that in 1950, the population was at around 150 million, and is expected to rise to over 450 million by 2100.

Figure 3. Projected Population in the United States: The United States has an intermediate fertility rate, and therefore, a comparatively moderate projected population growth. (Graph courtesy of USAID)

And low-fertility countries like China, Australia, and most of Europe will actually see population declines of approximately 20 percent.

A graph predicting the growing population of Europe. It shows that in 1950, the population was at around 550 million, then rose to 740 million in 2013, and is expected to fall to around 600 million by 2100.

Figure 4. Projected Population in Europe: This chart shows the projected population growth of Europe for the remainder of this century. (Graph courtesy of USAID)

GLOSSARY

carrying capacity:
the amount of people that can live in a given area considering the amount of available resources
cornucopian theory:
a theory that asserts human ingenuity will rise to the challenge of providing adequate resources for a growing population
demographic transition theory:
a theory that describes four stages of population growth, following patterns that connect birth and death rates with stages of industrial development
Malthusian theory:
a theory, associated with English clergyman Thomas Malthus, asserting that population is controlled through positive checks (war, famine, disease) and preventive checks (measures to reduce fertility such as birth control or celibacy)
zero population growth
a theoretical goal in which the number of people entering a population through birth or immigration is equal to the number of people leaving it via death or emigration

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