The Demographic Transition

All countries have experienced some changes in NIR, CBR, and CDR, but at different times and at different rates. The demographic transition helps to understand these differences. The demographic transition is a process of change in a society’s population from high crude birth and death rates and low rate of natural increase to a condition of low crude birth and death rates, low rate of natural increase, and higher total population.

Authoritative demographic sources, such as the Population Reference Bureau, the World Bank, and the United Nations, currently consider the demographic transition to consist of four stages. As discussed later in this chapter, some demographers anticipate a stage 5.

Demographic Transition Model

The four-stage demographic transition is characterized by two big breaks with the past. The first break with the past—the sudden drop in the death rate that comes from technological innovation—has been accomplished everywhere. The second break—the sudden drop in the birth rate that comes from changing social customs—has yet to be achieved in many countries.

Stage 1: Low Growth

• Very high CBR

• Very high CDR

• Very low NIR

Most of human history was spent in stage 1 of the demographic transition, but today no country remains in stage 1. Every nation has moved on to at least stage 2 and has experienced profound changes in population. For most of this period, people depended on hunting and gathering for food (see Chapter 9). When food was easily obtained, a region’s population increased, but it declined when people were unable to locate enough animals or vegetation nearby.

Stage 2: High Growth

• Still high CBR

• Rapidly declining CDR

• Very high NIR

Rapidly declining death rates and very high birth rates produce a very high natural increase. Europe and North America entered stage 2 of the demographic transition after 1750 as a result of the Industrial Revolution, which began in the United Kingdom in the late eighteenth century and diffused to the European continent and North America during the nineteenth century. The Industrial Revolution was a conjunction of major improvements in manufacturing goods and delivering them to market (see Chapter 11). The result of this transformation was an unprecedented level of wealth, some of which was used to make communities healthier places to live.

Stage 2 of the demographic transition did not diffuse to Africa, Asia, and Latin America until around 1950. The push of developing countries into stage 2 was caused by the medical revolution. Medical technology invented in Europe and North America has diffused to developing countries. Improved medical practices have eliminated many of the traditional causes of death in developing countries.

The Gambia is the smallest country in Africa, and one of the poorest. Fewer than 10 percent of women of reproductive age practice family planning. As a British colony until 1965, The Gambia was in Stage 1. The death rate declined rapidly beginning in the 1970s when the World Health Organization launched a program to immunize children in a number of countries, including The Gambia. This program helped to reduce the CDR in The Gambia, transitioning the country from stage 1 to stage 2, where it is now.

The Gambia: High Crude Birth Rate

Demographic Transition Stage 2: The Gambia

Stage 3: Moderate Growth

• Rapidly declining CBR

• Moderately declining CDR

• Moderate NIR

A country moves from stage 2 to stage 3 of the demographic transition when the CBR begins to drop sharply. The population continues to grow because the CBR is still greater than the CDR. But the rate of natural increase is more modest in countries in stage 3 than in those in stage 2 because the gap between the CBR and the CDR narrows.

A society enters stage 3 when people have fewer children. The decision to have fewer children is partly a delayed reaction to a decline in mortality. Economic changes in stage 3 societies also induce people to have fewer offspring. People in stage 3 societies are more likely to live in cities and to work in offices, shops, or factories rather than on farms. Farmers often consider a large family to be an asset because children can do some of the chores.

Most countries in Europe and North America (including the United States) moved from stage 2 to stage 3 of the demographic transition during the first half of the twentieth century. The movement took place during the second half of the twentieth century in many countries of Asia and Latin America, including Mexico.

Mexico entered stage 2 of the demographic transition during the twentieth century through a combination of lower death rates and higher birth rates. Mexico’s government believed that higher birth rates would be good for the country’s economic growth.

Mexico: Moderate Nir

Demographic Transition Stage 3: Mexico

A dramatic decline in birth rates came after 1974, when a constitutional amendment guaranteed families the legal right to decide on the number and spacing of children, and a National Population Council was established to promote family planning through education.

Stage 4: Low Growth

• Very low CBR

• Low or slightly increasing CDR

• 0 or negative NIR

A country reaches stage 4 when the CBR declines to the point where it equals the CDR and the NIR approaches zero. This condition is called zero population growth (ZPG), a term often applied to stage 4 countries.

ZPG may occur when the CBR is still slightly higher than the CDR because some females die before reaching childbearing years, and the number of females in their childbearing years can vary. To account for these discrepancies, demographers more precisely define ZPG as the TFR that results in a lack of change in the total population over a long term. A TFR of approximately 2.1 produces ZPG.

Social customs again explain the movement to stage 4. Increasingly, women in stage 4 societies enter the labor force rather than remain at home as full-time homemakers. People who have access to a wider variety of birth-control methods are more likely to use some of them.

Denmark entered stage 2 in the mid-nineteenth century and stage 3 in the late nineteenth century. Since the 1970s, Denmark has been in stage 4, with roughly equal CBR and CDR. The CDR is unlikely to decline unless another medical revolution, such as a cure for cancer, keeps elderly people alive much longer. Denmark may have entered a possible stage 5, with a declining NIR (see the section under Possible Demographic Transition Stage 5 later in this chapter).

Denmark: Aging Population

Demographic Transition Stage 4: Denmark

Pause & Reflect 2.2.3

Name a country not in Europe that appears to be in stage 4, according to