Botkin Environmental Science Earth as Living Planet 8th txtbk

4.4 The Demographic Transition 69
Male
3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Population (in millions)
Source: U.S. Census Bureau, International Data Base.
Kenya: 2008
100+
95–99
90–94
85–89
80–84
75–79
70–74
65–69
60–64
55–59
50–54
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
5–9
0–4
Few older people
Many young
people
Female
Male
Female
6 5 4 3 2 1 0 0 1 2 3 4 5 6
Population (in millions)
Source: U.S. Census Bureau, International Data Base.
Japan: 2008
100+
95–99
90–94
85–89
80–84
75–79
70–74
65–69
60–64
55–59
50–54
45–49
40–44
35–39
30–34
25–29
20–24
15–19
10–14
5–9
0–4
Fewer young
people
Male
United States: 2008
Female
85+
80–84
75–79
70–74
65–69
60–64
55–59
50–54
Baby
45–49
40–44
boom
35–39
30–34
25–29
20–24
15–19
10–14
5–9
0–4
16 14 12 10 8 6 4 2 0 0 2 4 6 8 10 12 14 16
Population (in millions)
Source: U.S. Census Bureau, International Data Base.
FIGURE 4.7 Age structure of Kenya, the United States, and Japan, 2008. The bars to
the left are males; those to the right are females. (Source: U.S. Bureau of the Census.)
ture also shows the baby boom that occurred in the
United States after World War II; a great increase in
births from 1946 through 1964 forms a pulse in the
population that can be seen as a bulge in the age structure,
especially of those aged 45–55 in 2008. At each
age, the baby boomers increased demand for social and
economic resources; for example, schools were crowded
when the baby boomers were of primary- and secondary-school
age.
4.4 The Demographic
Transition
The is a three-stage pattern of
change in birth rates and death rates that has occurred
during the process of industrial and economic development
of Western nations. It leads to a decline in population
growth.