Part Three

Population Structureand Characteristics

Part Outline

• 8 The Age Transition• 9 Population Aging• 10 The Family and Household

Transition• 11 The Urban Transition

Chapter 8

The Age Transition

Chapter Outline• The Concepts of Age and Age

Cohorts• The Concepts of Sex and Gender• Measuring the Dynamics of the Age

Transition• The Age Transition• Age Transitions at Work

Age and Age Cohorts• Society assigns social roles on the

basis of age and gender. Younger people are treated

differently from older people. Different kinds of behavior are

expected of people as they move through different ages.

Age Stratification Theory• Societies distribute resources unequally

by age. • These resources include economic goods

as well as social approval, acceptance, and respect.

• Age strata, and the prestige and power associated with each, are influenced by the needs of society and by characteristics of people at each age.

Aspects of Human Society that Vary by Age and Sex

Category Characteristic or Activity

Demographic Being sick and having restricted activities

Dying

Being sexually active

Having a baby

Moving or migrating

Aspects of Human Society that Vary by Age and Sex

Category Characteristic or Activity

Social Getting married/divorced

Being involved in religious organizations and activity

Being involved in political organizations and activity

Aspects of Human Society that Vary by Age and Sex

Category Characteristic or Activity

Social School enrollment

Level of educational attainment

Being involved in criminal behavior

Aspects of Human Society that Vary by Age and Sex

Category Characteristic or Activity

Economic Being in the labor force

Occupation within the labor force

Current income

Level of accumulated wealth

Lexis Diagram: Relationship between Cohorts and Period Data

Age Cohorts and Age Strata Are Closely Intertwined

Sex Ratios by Age in Selected Countries, 2004

Dynamics of the Age Transition• A population with 35% or more of its

people under age 15 is “young.”• A population with 12% or more of its

people aged 65 or older is “old.” • As the proportion of young people

increases relative to the total, the population “grows younger.”

• An aging population is one in which the proportion of older people is increasing relative to the total.

The Age Structure• There are three major ways to

quantify the age structure: Average age of a population Dependency ratio Growth rates by age

Population Pyramids

Changes in Number and Rate of Growth at Specific Ages

China India

Growth rate

Absolute change

Growth rate

Absolute change

Age Group

1980–2000

1980–2000

1980–2000

1980–2000

0–4 –0.15 –3,004 0.84 17,606

5–9 –0.97 –21,938 1.26 25,339

10–14 –0.50 –12,434 1.55 29,112

15–19 –0.35 –7,358 1.79 30,747

20–24 0.63 11,590 1.78 26,618

Changes in Number and Rate of Growth at Specific Ages

China India

Growth rate

Absolute change

Growth rate

Absolute change

Age Group 1980–2000

1980–2000

1980–2000

1980–2000

25–29 1.52 31,810 2.36 31,516

30–34 3.25 60,631 2.81 32,939

35–39 3.53 53,163 2.93 30,165

40–44 2.71 35,142 2.74 24,902

45–49 3.11 39,765 2.36 18,338

Changes in Number and Rate of Growth at Specific Ages

China India

Growth rate

Absolute change

Growth rate

Absolute change

Age Group 1980–2000

1980–2000

1980–2000

1980–2000

50–54 2.27 22,796 2.12 13,572

55–59 1.69 13,395 2.15 11,304

60–64 2.26 15,068 2.36 10,077

65–69 2.78 14,957 2.56 8,375

Changes in Number and Rate of Growth at Specific Ages

China India

Growth rate

Absolute change

Growth rate

Absolute change

Age Group 1980–2000

1980–2000

1980–2000

1980–2000

70–74 2.75 10,615 2.74 6,121

75–79 3.09 7,278 3.20 4,113

80+ 4.90 7,203 4.93 3,963

Stable and Stationary Populations• In a stable population neither the age-

specific birth rates nor the age-specific death rates have changed for a long time.

• A stable population could be growing at a constant rate or declining at a constant rate.

• If a stable population is unchanging, we call it a stationary population.

Global Distribution of Younger and Older Populations

Age Structure of Immigrants to U.S., 2002

Age Pyramids for U.S. With and Without International Migration

Age Structure of U.S.

Changing Age Structures in China, U.S. and Mexico