Age Structure and Population Limits

Questions for Today: What are the different age structures of a population and how will they determine future growth? What are different ways to slow down population growth? What are the four different stages in human population growth? What is the number one method to curb population growth?

Age Structures Age structure is the distribution of males and females among age groups in a population. Analyst plot the percentages of numbers of males and females in age structure diagrams or pyramids Three types of age structures: Prereproductive (0-14) Reproductive (15-44) Postreproductive (45 and older) Nearly 28% of the people on the planet were under 15 years of age in 2008

Age structure Diagrams Male Female Expanding Rapidly Guatemala Nigeria Saudi Arabia Expanding Slowly United States Australia China Stable Japan Italy Greece Declining Germany Bulgaria Russia Prereproductive ages 0–14 Reproductive ages 15–44 Postreproductive ages 45–85+

Age Structures Age structure vary in developed countries and developing countries. Developing countries will have a higher percentage of people in the prereproductive ages than developed countries.

Figure 6.9 Global outlook: population structure by age and sex in developing countries and developed countries, 2006. Question: If all girls under 15 had only one child during their lifetimes, how do you think these structures would change over time? (Data from United Nations Population Division and Population Reference Bureau) Fig. 6-9a, p. 131

Population (millions) Developing Countries 85+ 80–85 75–79 Male Female 70–74 65–69 60–64 55–59 50–54 45–49 40–44 Age 35–39 30–34 25–29 Figure 6.9 Global outlook: population structure by age and sex in developing countries and developed countries, 2006. Question: If all girls under 15 had only one child during their lifetimes, how do you think these structures would change over time? (Data from United Nations Population Division and Population Reference Bureau) 20–24 15–19 10–14 5–9 0–4 300 200 100 100 200 300 Population (millions) Fig. 6-9b, p. 131

Age Structures What happens when your pyramid is inverted? Japan: Population 2008: 128 million Population 2050: 96 million The Majority of Japan’s population is reaching their postreproductive ages.

Rising Death Rates Aside from a disproportion in the age structures, one of the major causes for population decline is AIDS and HIV. AIDS can affect a population by: Lowering life expectancy Loss of workforce

Slowing Population Growth Four major stages in demographic transition. Preindustrial Transitional Industrial Postindustrial As more developing countries move into the developed category, we will see a boom in population.

Birth rate and death rate Population grows very slowly because of a high birth rate (to compensate for high infant mortality) and a high death rate Stage 1 Preindustrial Growth rate over time 80 70 60 50 40 30 20 10 (number per 1,000 per year) Birth rate and death rate Low Death rate Total population Birth rate Population grows rapidly because birth rates are high and death rates drop because of improved food production and health Decreasing Stage 2 Transitional Increasing Very high Population growth slows as both birth and death rates drop because of improved food production, health, and education Stage 3 Industrial Low Population growth levels off and then declines as birth rates equal and then fall below death rates Stage 4 Postindustrial Negative Zero Figure 6.12 Four stages of the demographic transition, which the population of a country can experience when it becomes industrialized. There is uncertainty about whether this model will apply to some of today’s developing countries. See an animation based on this figure at CengageNOW. Question: At what stage is the country where you live? Stepped Art Fig. 6-12, p. 134

Methods to slowing population growth Family Planning Family planning provides educational and clinical services that help couples choose how many children to have and when to have them. Varies from culture to culture A Major Factor in reducing the number of births throughout the world 55% of a drop in TFR because of FP.

Family Planning Two problems: Most pregnancies in developing countries are unplanned and end with, usually, an illegal abortion. The lack of access to family planning services.

Family Planning Examples of Government Funded Family Planning: China’s One Child Policy Prefer Males Pledge to have one child, reap many benefits! India’s Family Planning Government provides Information and resources, but Couples still believe having large families is the best.

Empowering Women Studies show that women who are educated, hold a paying job, and live in societies where their rights are not suppressed have fewer children.