Part Three
Population Structure
and 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
Social
Characteristic or Activity
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
Social
Characteristic or Activity
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
Age
Group
China
Growth
Absolute
rate
change
1980–
1980–
2000
2000
India
Growth
Absolute
rate
change
1980–
1980–
2000
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
Age Group
China
Growth
Absolute
rate
change
1980–
1980–
2000
2000
India
Growth
Absolute
rate
change
1980–
1980–
2000
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
Age Group
50–54
55–59
60–64
65–69
China
Growth
Absolute
rate
change
1980–
1980–
2000
2000
2.27
22,796
1.69
13,395
2.26
15,068
2.78
14,957
India
Growth
Absolute
rate
change
1980–
1980–
2000
2000
2.12
13,572
2.15
11,304
2.36
10,077
2.56
8,375
Changes in Number and Rate
of Growth at Specific Ages
Age Group
70–74
75–79
80+
China
Growth
Absolute
rate
change
1980–
1980–
2000
2000
2.75
10,615
3.09
7,278
4.90
7,203
India
Growth
Absolute
rate
change
1980–
1980–
2000
2000
2.74
6,121
3.20
4,113
4.93
3,963
Stable and Stationary
Populations
• In a stable population neither the agespecific 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