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 Male Female Male Female Male Female

Expanding Rapidly Guatemala

Nigeria Saudi Arabia

Expanding Slowly United States

Australia China

Stable Japan Italy

Greece

Declining GermanyBulgaria 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.

Fig. 6-9a, p. 131

Fig. 6-9b, p. 131

Developing Countries

80–8585+

75–7970–74

Male Female

60–6465–69

55–5950–5445–49

35–39Ag

e 40–44

25–2930–34

20–24

10–1415–19

5–90–4

300 200 100 0 100 200 300

Population (millions)

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.

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 2Transitional

Increasing Very high

Population growth levels off and then declines as birth rates equal and then fall below death rates

Stage 4Postindustrial

NegativeZero

Populationgrows veryslowly becauseof a highbirth rate(to compensatefor high infantmortality) and ahigh death rate

Stage 1Preindustrial

Growth rate over time

80

70

60

50

40

30

20

10

0

Bir

th r

ate

an

d d

eath

rat

e(n

um

ber

per

1,0

00 p

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yea

r)

Low

Population growth slows as both birthand death rates drop because of improved food production, health, and education

Stage 3Industrial

Low

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 less children.