1. The Human Population and Its Impact
Chapter 8

2. Crowded Street in China

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

4. 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

5. Consider this
In 1905 the three leading causes of death in the United States were pneumonia, tuberculosis and diarrhea.
90% of US doctors had NO college education

6. 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?

7. Video: Bonus for a baby

8. Video: People explosion

9. Animation: Resources depletion and degradation

10. 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- the number of live births/1000 in a given year.
Crude death rate- the number of deaths per 100 in a given year

11. Women Having Fewer Babies but Not Few Enough to Stabilize the World’s Population
Fertility rate
Replacement-level fertility rate- the number of children a couple must bear to replace themselves.
Total fertility rate (TFR)- the number of children a woman has during her reproductive years World wide in

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

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

14. 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

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

16. Several Factors Affect Death Rates (1)
Life expectancy-average number of years a newborn infant can expect to live.
Infant mortality rate – the number of babies out of every 1000 that die before their first birthday

17. Why are people living longer and fewer infants dying?
Increased food supply and distribution
Better nutrition
Medical advances
Improved sanitation

18. 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

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

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

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

22. 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

23. 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.

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

25. Generalized Population Age Structure Diagrams

26. 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

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

28. 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

29. 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

30. 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

31. 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

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

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

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

35. Some Problems with Rapid Population Decline

36. 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

37. 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

38. Active Figure: Examples of age structure

39. Active Figure: U.S. age structure

40. 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.

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

42. Four Stages of the Demographic Transition

43. 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

44. 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

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

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

47. 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

48. Active Figure: Demographic transition model

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