1. The Human Population and Its Impact
Chapter 6

2. Core Case Study: Are There Too Many of Us? (1)
Estimated 2.4 billion more people by 2050
Are there too many people already?
Will technological advances overcome environmental resistance that populations face?
Should populations be controlled?

3. Core Case Study: Are There Too Many of Us? (2)
Will growing populations cause increased environmental stresses?
Infectious diseases
Biodiversity losses
Water shortages
Traffic congestion
Pollution of the seas
Climate change

4. Crowded Street in China

5. 6-1 How Many People Can the Earth Support?
Concept 6-1 We do not know how long we can continue increasing the earth’s carrying capacity for humans without seriously degrading the life-support system for humans and many other species.

6. Human Population Growth Continues but It Is Unevenly Distributed (1)
Reasons for human population increase
Movement into new habitats and climate zones
Early and modern agriculture methods
Control of infectious diseases through
Sanitation systems
Antibiotics
Vaccines

7. Human Population Growth Continues but It Is Unevenly Distributed (2)
Population growth in developing countries is increasing 15 times faster than developed countries
By 2050, 97% of growth will be in developing countries
Should the optimum sustainable population be based on cultural carrying capacity?

8. Global Connections: UN World Population Projections by 2050

9. Population (billions)12 11
High10.8 10
Medium 9.3 9 8 7
Population (billions)
Low7.8 6 5
Figure 6.2
Global connections: UN world population projections, assuming that by 2050 women will have an average of 2.5 children (high), 2.0 children (medium), or 1.5 children (low). The most likely projection is the medium one—9.3 billion by (Data from United Nations). 4 3 2
1950
1960
1970
1980
1990
2000
2010
2020
2030
2040
2050
Year
Fig. 6-2, p. 125

10. Science Focus: How Long Can the Human Population Keep Growing?
Thomas Malthus and population growth: 1798
Humans have altered 83% of the earth’s land surface
Can the human population grow indefinitely?

11. Natural Capital Degradation: Altering Nature to Meet Our Needs

12. NATURAL CAPITAL DEGRADATION
Altering Nature to Meet Our Needs
Reduction of biodiversity
Increasing use of the earth's net primary productivity
Increasing genetic resistance of pest species and disease-causing bacteria
Elimination of many natural predators
Introduction of potentially harmful species into communities
Figure 6.A
Major ways in which humans have altered the rest of nature to meet our growing population’s resource needs and wants. See an animation based on this figure at CengageNOW. Questions: Which three of these items do you believe have been the most harmful? Explain. How does your lifestyle contribute directly or indirectly to each of these three items?
Using some renewable resources faster than they can be replenished
Interfering with the earth's chemical cycling and energy flow processes
Relying mostly on polluting and climate-changing fossil fuels
Fig. 6-A, p. 124

13. Animation: Current and projected population sizes by region

14. Video: Bonus for a baby

15. Video: People explosion

16. Animation: Resources depletion and degradation

17. 6-2 What Factors Influence the Size of the Human Population?
Concept 6-2A Population size increases because of births and immigration and decreases through deaths and emigration.
Concept 6-2B The average number of children born to women in a population (total fertility rate) is the key factor that determines population size.

18. The Human Population Can Grow, Decline, or Remain Fairly Stable
Population change
Births: fertility
Deaths: mortality
Migration
Population change =
(births + immigration) – (deaths + emigration)
Crude birth rate
Crude death rate

19. Global Connections: The World’s 10 Most Populous Countries in 2008

20. China India USA Indonesia Pakistan Brazil Nigeria Bangladesh Russia
1.3 billion
1.5 billion
India
1.1 billion
1.4 billion
USA
304 million
357 million
Indonesia
240 million
292 million
Pakistan
173 million
229 million
Brazil
195 million
229 million
Nigeria
148 million
205 million
Figure 6.3
Global connections: the world’s 10 most populous countries in 2008, with projections of their population sizes in (Data from World Bank and Population Reference Bureau)
147 million
Bangladesh
180 million
Russia
142 million
129 million
2008
2025
Japan
128 million
119 million
Fig. 6-3, p. 126

21. Women Having Fewer Babies but Not Few Enough to Stabilize the World’s Population
Fertility rate
Replacement-level fertility rate
Total fertility rate (TFR)

22. Case Study: The U.S. Population Is Growing Rapidly
Drop in TFR in U.S.
Rate of population growth has slowed
Population still growing and not leveling off
Fourfold increase since 1900
Changes in lifestyle in the U.S. during the 20th century

23. TFR Rates for the U.S. between 1917 and 2008

24. Baby boom (1946–64) Replacement level
4.0
3.5
3.0
2.5
2.1
Births per woman
2.0
Baby boom
(1946–64)
Replacement level
1.5
1.0
Figure 6.4
Total fertility rates for the United States between 1917 and Question: The U.S. fertility rate has declined and remained at or below replacement levels since 1972, so why is the population of the United States still increasing? (Data from Population Reference Bureau and U.S. Census Bureau)
0.5
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Year
Fig. 6-4, p. 127

25. Birth Rates in the U.S. from 1910 to 2008

26. Demographic transition32 30 28 26 24 22
Births per thousand population 20 18 16
End of World War II
Demographic transition 14
Depression
Baby boom
Baby bust
Echo baby boom
Figure 6.5
Birth rates in the United States, 1910–2008. Use this figure to trace changes in crude birth rates during your lifetime. (Data from U.S. Bureau of Census and U.S. Commerce Department)
1910
1920
1930
1940
1950
2000
2010
1960
1970
1980
1990
Year
Fig. 6-5, p. 127

27. Some Major Changes That Took Place in the U.S. between 1900 and 2000

28. Married women working outside the home 8% 81%
47 years
Life expectancy
77 years
Married women working outside the home 8%
81%
15%
High school graduates
83%
10%
Homes with flush toilets
98% 2%
Homes with electricity
99%
Living in suburbs
10%
Figure 6.6
Some major changes that took place in the United States between 1900 and Question: Which two of these changes do you think were the most important? (Data from U.S. Census Bureau and Department of Commerce)
52%
1900
Hourly manufacturing job wage (adjusted for inflation) $3
2000
$15
Homicides per 100,000 people
1.2
5.8
Fig. 6-6, p. 128

29. Married women working outside the home 8% 81%
77 years
Life expectancy
47 years
1900
2000
Married women working outside the home 8%
81%
High school graduates
15%
83%
Homes with flush toilets
10%
98%
Homes with electricity 2%
99%
Living in suburbs
10%
52%
Figure 6.6
Some major changes that took place in the United States between 1900 and Question: Which two of these changes do you think were the most important? (Data from U.S. Census Bureau and Department of Commerce)
Hourly manufacturing job wage (adjusted for inflation) $3
$15
Homicides per 100,000 people
1.2
5.8
Stepped Art
Fig. 6-6, p. 128

30. Several Factors Affect Birth Rates and Fertility Rates (1)
Children as part of the labor force
Cost of raising and educating children
Availability of private and public pension
Urbanization
Educational and employment opportunities for women

31. Several Factors Affect Birth Rates and Fertility Rates (2)
Infant mortality rate
Average age of a woman at birth of first child
Availability of legal abortions
Availability of reliable birth control methods
Religious beliefs, traditions, and cultural norms

32. Several Factors Affect Death Rates (1)
Life expectancy
Infant mortality rate
Why are people living longer and fewer infants dying?
Increased food supply and distribution
Better nutrition
Medical advances
Improved sanitation

33. Several Factors Affect Death Rates (2)
U.S. infant mortality rate high due to
Inadequate health care for poor women during pregnancy and their infants
Drug addiction among pregnant women
High birth rate among teenagers

34. Migration Affects an Area’s Population Size
Economic improvement
Religious freedom
Political freedom
Wars
Environmental refugees

35. Case Study: The United States: A Nation of Immigrants
Historical role of immigration in the U.S.
Legal immigration
Illegal immigration

36. Legal Immigration to the U.S. between 1820 and 2003

37. New laws restrict immigration 1,200
2,000
1,800
1,600
1,400
1907
1914
New laws restrict immigration
1,200
Number of legal immigrants (thousands)
1,000
800
Great Depression
600
Figure 6.7
Legal immigration to the United States, 1820–2003 (the last year for which data are available). The large increase in immigration since 1989 resulted mostly from the Immigration Reform and Control Act of 1986, which granted legal status to illegal immigrants who could show they had been living in the country for several years. (Data from U.S. Immigration and Naturalization Service and the Pew Hispanic Center)
400
200
1820
1840
1860
1880
1900
1920
1940
1960
1980
2000
2010
Year
Fig. 6-7, p. 129

38. 6-3 How Does a Population’s Age Structure Affect Its Growth or Decline?
Concept 6-3 The numbers of males and females in young, middle, and older age groups determine how fast a population grows or declines.

39. Populations Made Up Mostly of Young People Can Grow Rapidly
Age structure categories
Prereproductive ages
Reproductive ages
Postreproductive ages

40. Generalized Population Age Structure Diagrams

41. Expanding Rapidly Guatemala Nigeria Saudi Arabia
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
Germany
Bulgaria
Russia
Figure 6.8
Generalized population age structure diagrams for countries with rapid (1.5–3%), slow (0.3–1.4%), zero (0–0.2%), and negative (declining) population growth rates. A population with a large proportion of its people in the prereproductive age group (far left) has a large potential for rapid population growth. See an animation based on this figure at CengageNOW. Question: Which of these figures best represents the country where you live? (Data from Population Reference Bureau)
Prereproductive ages
0–14
Reproductive ages
15–44
Postreproductive ages
45–85+
Fig. 6-8, p. 131

42. Population Structure by Age and Sex in Developing and Developed Countries

43. Figure 6.9
Global outlook: population structure by age and sex in developing countries and developed countries, Question: If all girls under 15 had only one child during their lifetimes, how do you think these structures would change over time? (Data from United Nations Population Division and Population Reference Bureau)
Fig. 6-9a, p. 131

44. Population (millions)
Developed Countries
85+
80–85
75–79
Male
70–74
Female
65–69
60–64
55–59
50–54
45–49
40–44
Age
35–39
30–34
25–29
Figure 6.9
Global outlook: population structure by age and sex in developing countries and developed countries, Question: If all girls under 15 had only one child during their lifetimes, how do you think these structures would change over time? (Data from United Nations Population Division and Population Reference Bureau)
20–24
15–19
10–14
5–9
0–4
300
200
100
100
200
300
Population (millions)
Fig. 6-9a, p. 131

45. Figure 6.9
Global outlook: population structure by age and sex in developing countries and developed countries, Question: If all girls under 15 had only one child during their lifetimes, how do you think these structures would change over time? (Data from United Nations Population Division and Population Reference Bureau)
Fig. 6-9b, p. 131

46. Population (millions)
Developing Countries
85+
80–85
75–79
Male
Female
70–74
65–69
60–64
55–59
50–54
45–49
40–44
Age
35–39
30–34
25–29
Figure 6.9
Global outlook: population structure by age and sex in developing countries and developed countries, Question: If all girls under 15 had only one child during their lifetimes, how do you think these structures would change over time? (Data from United Nations Population Division and Population Reference Bureau)
20–24
15–19
10–14
5–9
0–4
300
200
100
100
200
300
Population (millions)
Fig. 6-9b, p. 131

47. We Can Use Age-Structure Information to Make Population and Economic Projections
Baby boomers
Job market when they retire

48. Tracking the Baby-Boom Generation in the United States

49. Populations Made Up of Mostly Older People Can Decline Rapidly
Slow decline
Manageable
Rapid decline
Severe economic problems
Severe social problems

50. Some Problems with Rapid Population Decline

51. Some Problems with Rapid Population Decline
Can threaten economic growth
Labor shortages
Less government revenues with fewer workers
Less entrepreneurship and new business formation
Less likelihood for new technology development
Figure 6.11
Some problems with rapid population decline. Question: Which three of these problems do you think are the most important?
Increasing public deficits to fund higher pension and health-care costs
Pensions may be cut and retirement age increased
Fig. 6-11, p. 133

52. Populations Can Decline from a Rising Death Rate: The AIDS Tragedy
25 million killed by 2008
Many young adults die: loss of most productive workers
Sharp drop in life expectancy
International community called upon to
Reduce the spread of HIV through education and health care
Financial assistance and volunteers

53. Active Figure: Examples of age structure

54. Active Figure: U.S. age structure

55. 6-4 How Can We Slow Human Population Growth?
Concept 6-4 Experience indicates that the most effective ways to slow human population growth are to encourage family planning, to reduce poverty, and to elevate the status of women.

56. As Countries Develop, Their Populations Tend to Grow More Slowly
Demographic transition stages
Preindustrial
Transitional
May lead to a demographic trap
Industrial
Postindustrial

57. Four Stages of the Demographic Transition

58. Birth rate and death rate
Population
grows very
slowly because
of a high
birth rate
(to compensate
for high infant
mortality) and a
high death rate
Stage 1
Preindustrial
Growth rate over time 80 70 60 50 40 30 20 10
(number per 1,000 per year)
Birth rate and death rate
Low
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 2
Transitional
Increasing
Very high
Population growth slows as both birth
and death rates drop because of improved food production, health, and education
Stage 3
Industrial
Low
Population growth levels off and then declines as birth rates equal and then fall below death rates
Stage 4
Postindustrial
Negative
Zero
Figure 6.12
Four stages of the demographic transition, which the population of a country can experience when it becomes industrialized. There is uncertainty about whether this model will apply to some of today’s developing countries. See an animation based on this figure at CengageNOW. Question: At what stage is the country where you live?
Stepped Art
Fig. 6-12, p. 134

59. Planning for Babies Works
Family Planning
Responsible for a 55% drop in TFRs
In developing countries
Expansion of program
Include teenagers, sexually active unmarried women, and men
Slow and stabilize population growth
Invest in family planning
Reduce poverty
Elevate the social and economic status of women

60. Empowering Women Can Slow Population Growth
Education
Paying jobs
Human rights without suppression
“For poor women the only holiday is when you are asleep”

61. Women from a Village in Burkina Faso Returning with Fuelwood

62. Case Study: Slowing Population Growth in China: the One-Child Policy
Encourages fewer children
Gender imbalance
Fast-growing economy
Face serious resource and environmental problems

63. Active Figure: Demographic transition model

64. Case Study: Slowing Population Growth in India
Population control: gender bias
Poverty
Malnutrition
Environmental problems