Why?
3/27/12
CHAPTER 4 HUMAN POPULATIONS
ONE-CHILD CHINA GROWS
UP
A country faces the outcomes of radical population control
The growth rate of a
population is the percent
increase of population size
over time.
The growth rate is affected
by births, deaths, and the
number of people moving
into or out of a regional
population.
Global human population has
had two growth spurts:
Agricultural revolution,
10,000 years ago
Industrial Revolution,
1700s
China’s standard of living
improved greatly in the
second half of the 20th
Century. Life expectancy
increased from 45 to 60
years old.
China’s crude death rate fell,
but its crude birth rate held
steady. By 1970, China’s
population had swelled to
nearly 900 million.
Other developed nations have
gone through this demographic
transition from high birth and
death rates to low birth and
death rates.
China supports a
quarter of the
world’s population
on just 7 percent of
the planet’s arable
land (fit for growing
crops).
In the 1950s, famine claimed 30
million lives in China. In the
1970s, shortages in consumer
goods led to rationing. The
government blamed
overpopulation.
In the 1970s, China feared more
growth:
Two-thirds of the population was
under the age of 30
Those born in 1950s, 1960s were
entering their reproductive years
In 1979, China issued a
decree: No family could have
more than one child.
Explain the differences between
these age structure diagrams
3/27/12
China’s goal (shared by
many countries): zero
population growth.
This occurs when the number of
people born equals the number
of people dying; in other words,
replacement fertility rate is
reached.
Reaching zero population growth
takes two steps:
Identifying why birth rates are high
Taking steps to reduce them
Demographers use age structure
diagrams to predict the future growth
potential of a population.
Age structure diagrams show:
Age structure: percentage of
population in various age groups
•
Sex ratio: number of males per
1,000 females.
•
Clicker Question
Country B
Age
Country A
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
Males
Females
Males
Females
12 10 8
6
4
Country C
2
0
2
4
6
8 10 12 12 10
8
6
4
Males
Females
2
0
2
4
6
8
10 12 12 10
8
6
4
2
0
2
4
6
8 10 12
% Total Population
Based on the age structure diagrams above, which country has
the highest capacity for growth and will experience the highest
growth rate?
A. Country A
B. Country B
C. Country C
D. Countries A & B
Clicker Question
Country B
Age
Country A
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
Males
Females
Males
Females
12 10 8
6
4
Country C
2
0
2
4
6
8 10 12 12 10
8
6
4
Males
Females
2
0
2
4
6
8
10 12 12 10
8
6
4
2
0
2
4
6
8 10 12
% Total Population
Which country would you classify as mature and most likely
to experience stable population growth?
A. Country A
B. Country B
C. Country C
D. Countries A & B
Many industrialized nations have
top-heavy age structure diagrams
with many older people (the
United States, for example)
These countries struggle to care
for rapidly aging populations:
•
•
U.S. baby boomers’ retirement fuels
debates on Social Security
France raised retirement age from
60 to 62
Do Now
With the world population now over 7
billion people, and scheduled to reach 8
billion in 2023, what can be done to stop
or slow the growth rate? What is being
done now if anything?
3/27/12
China’s age structure diagram has
changed since the one-child policy:
•
•
In 1982, 5% older than 65
By 2050, 15% projected to be older
than 65
China’s sex ratio of males to
females also changed:
• In 1979, the ratio was 1.06
• In 2011, the ratio was 1.17
By 2020, it is estimated that there will be 30
million more men than women in China.
New problems for China:
• Fewer adult children to care
for aging relatives
• Fewer young workers
• Fewer women for men to marry
In 2011, China began
considering allowing
select couples to have a
second child.
Worldwide, population growth rates are
declining, but the overall number is still positive,
so world population is still growing.
Every environment has a carrying
capacity – the maximum population
size the area can support.
There are roughly 7 billion
people on the planet today. We
may have already exceeded
Earth’s carrying capacity.
One problem we face is our
dependence on nonrenewable
energy sources: they will not
last indefinitely.
Whether we stabilize at 9 or 10
billion or more depends on how
quickly we lower total fertility
rates (TFR) worldwide.
Many demographers believe
addressing social justice issues
of overpopulation will help
countries with high TFRs
confront what lies ahead.