Printed Page 188 7.3 Many nations go through a demographic [Notes/Highlighting] transition Before 1600, the global average population growth rate was typically below 0.1 percent per year, meaning that the time it would have taken for the population to double was more than 700 years. Then, as technology, health care, and sanitation improved, the growth rate increased dramatically. By 1965, the doubling time for the global population was 42 years. Since then, the global population growth rate has slowed, and most demographers believe that Earth’s population is likely to level off by 2100 without ever doubling again. Demographers need to understand why the rate of population growth fluctuated so much in the past and whether there are lessons they can learn from those fluctuations that will help us understand the future. Developing and testing theories is one way to gain this understanding. Previous Section | Next Section 7.3.1 The Theory of Demographic Transition Printed Page 188 [Notes/Highlighting] Historically, nations that have gone through similar processes of economic development have experienced similar patterns of population growth. Scientists who studied the population growth patterns of European countries in the early 1900s described a four-phase process they referred to as a demographic transition. The theory of demographic transition says that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a predictable shift in population growth. The four phases of a demographic transition are shown in FIGURE 7.9. At the beginning of the transition, called phase 1, the country experiences slow growth or no growth. This phase is followed by rapid growth in phase 2. Many countries in Africa and some Asian countries, such as China and India, are classified Figure 7.9 Demographic transition. The theory of as being in phase 2. Countries such as the United demographic transition models the way that birth, death, and growth rates for a nation change with economic States, Canada, and Australia are in phase 3, development. Phase 1 is a preindustrial period which is characterized by population stabilization. characterized by high birth rates and high death rates. In In phase 4, the population declines. Some western phase 2, as the society begins to industrialize, death rates European nations are currently in this phase. drop rapidly, but birth rates do not change. Population growth is the greatest at this point. In phase 3, birth rates The theory of demographic transition, while decline for a variety of reasons. In phase 4, the population stops growing and sometimes begins to decline as birth helpful as a learning tool, does not adequately rates drop below death rates. describe the population growth patterns of some developing countries today or in the last quarter- century. Birth and death rates have declined rapidly in a number of developing countries as a result of a variety of factors that are not yet entirely understood. In some developing countries the government has taken measures to improve health care and sanitation and promote birth control, in spite of the country’s poverty. For example, in Nicaragua, the second poorest country in the Western Hemisphere, birth and death rates declined rapidly in the 1980s and 1990s, and there has been no increase in the 0 to 5-year age range since 1990. Nicaragua displays the birth rate and death rate patterns of a phase 4 country although its industrial activity is that of a developing country. In contrast, China is economically and industrially ahead of Nicaragua, and arguably behind the United States, yet its population growth rate is slightly lower than that of the United States, in large part because of the Chinese government’s one-child policy. Despite the limitations of the theory of demographic transition, it is worth examining in more detail because it allows us to understand the way some countries will influence the environment as they undergo growth and development. PHASE 1: SLOW POPULATION GROWTH Phase 1 represents a population that is nearly at steady state. The size of the population will not change very quickly because high birth rates and high death rates offset one another. In other words, crude birth rate roughly equals crude death rate. This pattern is typical of countries before they begin to modernize. In these countries, life expectancy for adults is relatively short due to difficult and often dangerous working conditions. The infant mortality rate is also high because of disease, lack of health care, and poor sanitation, and as a result, many families have more children than they expect will live to adulthood. In a subsistence economy, where most people are farmers, having numerous children is an asset. Children can do jobs such as collecting firewood, tending crops, watching livestock, and caring for younger siblings. With no social security system, parents also count on having many children to care for them when they become old. Western Europe and the United States were in phase 1 before the Industrial Revolution, from the late eighteenth to the mid-nineteenth century. Today, crude birth rates exceed crude death rates in almost every country, so even the poorest nations have moved beyond phase 1. However, an increase in crude death rates due to war, famine, and diseases such as AIDS has pushed some countries back in the direction of phase 1. Lesotho (CBR = 25, CDR = 23) is an example of a country that may have recently moved backward into phase 1. PHASE 2: RAPID POPULATION GROWTH In phase 2, death rates decline while birth rates remain high, and as a result, the population grows rapidly. As a country modernizes, better sanitation, clean drinking water, increased access to food and goods, and access to health care, including childhood vaccinations, all reduce the infant mortality rate and CDR. However, the CBR does not markedly decline. Couples continue to have large families because it takes at least one generation, if not more, for people to notice the decline in infant mortality and adjust to it. This is another example of population momentum. It also takes time to implement educational systems and birth control measures. A phase 2 country is in a state of imbalance: births outnumber deaths. India is in phase 2 today. The United States population exhibited a phase 2 population pyramid in the early twentieth century when there were high birth rates, high death rates, and a large total fertility rate. PHASE 3: STABLE POPULATION GROWTH A country enters phase 3 as its economy and educational system improve. In general, as family income increases, people have fewer children, as FIGURE 7.10 shows. As a result, the CBR begins to fall. Phase 3 is typical of many developed countries, including the United States and Canada. Figure 7.10 Total fertility rate versus per capita income. Wealthier nations tend to have lower total fertility rates. [Data from http://www.gapminder.org, 2007 data.] Why do people produce fewer children as their income increases? As societies transition from subsistence farming to more complex economic specializations, having large numbers of children may become a financial burden rather than an economic benefit. Relative affluence, more time spent pursuing education, and the availability of birth control increase the likelihood that people will choose to have smaller families. However, it is important to note that cultural, societal, and religious norms may also play a role in birth rates. As birth rates and death rates decrease in phase 3, the system returns to a steady state. Population growth levels off during this phase, and population size does not change very quickly, because low birth rates and low death rates cancel each other out. PHASE 4: DECLINING POPULATION GROWTH Phase 4 is characterized by declining population size and often by a relatively high level of affluence and economic development. Japan, the United Kingdom, Germany, Russia, and Italy are phase 4 countries, with the CBR well below the CDR. The declining population in phase 4 means fewer young people and a higher proportion of elderly people (FIGURE 7.11). This demographic shift can have important social and economic effects. With fewer people in the labor force and more people retired or working part-time, the ratio of dependent elderly to wage earners increases, and pension programs and social security services put a greater tax burden on each wage earner. There may be a shortage of health care workers to care for an aging country. Governments may encourage immigration as a source of additional workers. In some countries, such as Japan, the government provides economic incentives to encourage families to have more children in order to offset the demographic shift. Recent studies on demographic shifts in highly developed countries suggest that the TFR actually increases after reaching a low point between 1.2 and 1.5. The reasons for the increase are unclear, but it appears that when a population becomes affluent and well educated, it becomes somewhat Figure 7.11 Some countries have very large elderly populations. Here, men and women gather at a senior easier for women to raise children, and they residence home in Hamburg, Germany. choose to do so in slightly greater numbers. Such a pattern is occurring in Norway, Italy, the United States, and other developed nations. Previous Section | Next Section 7.3.2 Family Planning Printed Page 190 [Notes/Highlighting] We have already observed that as family income increases, people tend to have fewer children. In fact, there is a link between higher levels of education and affluence among females, in particular, and lower birth rates. As the education levels of women increase and women earn incomes of their own, fertility generally decreases.