1. The Human Population and Urbanization
Chapter 6

2. How Many people can the earth support?
Section 6-1
How Many people can the earth support?

3. Human population growth continues but it is unevenly distributed
For most of history, the human population grew slowly, but has been growing exponentially for the past 200 years. Reasons for this increase in growth rate include:
Humans have expanded into almost all of the planet’s climate zones and habitats.
The emergence of early and modern agriculture allowed us to grow more food for each unit of land area farmed.
Death rates dropped sharply because of improved sanitation and health care.

4. Human population growth continues but it is unevenly distributed
The rate of population growth has slowed, but the world’s population is still growing at a rate that added about 83 million people during 2011.
Geographically, growth is unevenly distributed.
About 1% of the 83 million new arrivals on the planet in 2011 were added to the world’s more-developed countries
The other 99% were added to the world’s middle- and low-income, less-developed countries.
At least 95% of the 2.6 billion people likely to be added to the world’s population between 2011 and 2050 will end up in the least-developed countries.

5. Annual growth of world population, 1950-2011

6. Average annual global growth rate (percent)
2.5
2.0
1.5
Average annual global growth rate (percent)
1.0
Figure 6.2: This graph tracks the annual growth rate of world population, 1950–2010, with projections to (Data from United Nations Population Division and U.S. Census Bureau)
0.5
0.0
1950
1970
1990
2010
2030
2050
Year
Fig. 6-2, p. 97

7. Human population growth continues but it is unevenly distributed
Cultural carrying capacity is the maximum number of people who could live in:
reasonable freedom and comfort indefinitely,
without decreasing the ability of the earth to sustain future generations.
How do we come up with this metric?

8. What factors influence the size of the human population?
Section 6-2
What factors influence the size of the human population?

9. The human population can grow, decline, or remain fairly stable
Birth rate, or crude birth rate, is the number of live births per 1,000 people in a population in a given year.
Death rate, or crude death rate, is the number of deaths per 1,000 people in a population in a given year.
Population change of an area = (births + immigration) - (deaths + emigration)

10. Women are having fewer babies but not few enough to stabilize the world’s population
The total fertility rate (TFR) is the average number of children born to women in a population during their reproductive years.
Between 1955 and 2011, the average global lifetime number of births of live babies per woman dropped from 5 to 2.5.
A TFR of 2.1 will eventually halt the world’s population growth.

11. Total fertility rates for the US between 1917-2011

12. Baby boom (1946–64) Replacement level
4.0
3.5
3.0
Births per woman
2.5
2.1
2.0
1.5
Baby boom (1946–64)
Replacement level
1.0
0.5
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Figure 6.3: The top graph shows the total fertility rates for the United States between 1917 and 2010 and the bottom graph shows the country’s birth rate between 1917 and Question: The U.S. fertility rate has declined and remained at or below replacement levels since So why is the population of the United States still increasing? (Data from Population Reference Bureau and U.S. Census Bureau)
Year
Fig. 6-3, p. 98

13. Some major changes took place in the US between 1900-2000

14. Which two are the most important contributors to standard of living?
47 years
Life expectancy
77 years
Which two are the most important contributors to standard of living?
Married women working outside the home 8%
81%
High school graduates
15%
83%
Homes with flush toilets
10%
98%
Homes with electricity 2%
99%
People living in suburbs
10%
Figure 6.4: This chart lists 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 $3
2000
$15
Homicides per 100,000 people
1.2
5.8
Fig. 6-4, p. 99

15. Several factors affect birth rates and fertility rates
A particular country’s average birth rate and TFR can be affected by:
The importance of children as a part of the labor force.
The cost of raising and educating children.
The availability of, or lack of, private and public pension systems.
Urbanization.

16. Several factors affect birth rates and fertility rates
The educational and employment opportunities available for women.
The average age at marriage.
The availability of legal abortions.
The availability of reliable birth control methods.
Religious beliefs, traditions, and cultural norms.

17. Several factors affect death rates
People started living longer and fewer infants died because of:
increased food supplies and
distribution, better nutrition, medical advances, improved sanitation, life expectancy, married women working, and safer water supplies.

18. Several factors affect death rates
Two useful indicators of the overall health of people in a country or region are life expectancy and infant mortality rate:
The average global life expectancy increased from 48 years in 1955 to 69 years in 2011.
Between 1900 and 2011, the average global life expectancy in the United States increased from 47 years to 78 years.

19. Child laborers in India

20. Several factors affect death rates
Infant mortality is a measure of a society’s quality of life because it reflects the general level of nutrition and health care.
A high infant mortality rate can results from insufficient food (undernutrition), poor nutrition (malnutrition), and a high incidence of infectious disease, which is exacerbated by under- or malnutrition.
While infant mortality rates in more-developed and less-developed countries have declined dramatically since 1965, more than 4 million infants die during their first year of life.

21. Several factors affect death rates
The U.S. ranks 54th in the world in infant mortality rates due to:
inadequate health care for poor women during pregnancy and for their babies after birth
drug addiction among pregnant women
a high teenage pregnancy rate

22. Migration affects an area’s population size
Migration is the movement of people into (immigration) and out of (emigration) specific geographic areas.
Most people who migrate from one country to another are seeking jobs.

23. Migration affects an area’s population size
Religious persecution, ethnic conflicts, political oppression, wars, and certain types of environmental degradation are also factors.
Environmental refugees are people who migrate due to environmental degradation such as soil erosion and water and food shortages. One UN study estimated that a million people are added to this category every year.

24. CASE STUDY: The United States: A Nation of Immigrants
Since 1820, the United States has admitted almost twice as many immigrants and refugees as all other countries combined.
Legal and illegal immigration account for about 36% of the country’s annual population growth.

25. CASE STUDY: The United States: A Nation of Immigrants
Between 1820 and 1960, most legal immigrants to the United States came from Europe. Since 1960, most have come from Latin America and Asia. Hispanics are projected to make up 30% of the U.S. population by 2050.

26. CASE STUDY: The United States: A Nation of Immigrants
There is controversy over reducing legal immigration to the U.S.
Proponents of reducing immigration say it would help stabilize population size and reduce the country’s enormous environmental impact.

27. CASE STUDY: The United States: A Nation of Immigrants
There is controversy over reducing legal immigration to the U.S.
Those against say it would diminish the role of the U.S. as a land of opportunity and take away from cultural diversity and innovation. Most immigrants and their descendants start new businesses and create jobs. Many immigrants take menial and low-paying jobs that most other Americans shun.

28. CASE STUDY: The United States: A Nation of Immigrants
There were an estimated 11 million illegal immigrants in the United States in There is controversy over what to do about illegal immigration.
Some want to deport all illegal immigrants.
Others want to set up programs that allow illegal immigrants to remain in the country as long as they are working towards citizenship.

29. Legal immigration to the US, 1820-2006

30. New laws restrict immigration 1,200
2,000
1,800
1,600
1907
1,400
1914
New laws restrict immigration
1,200
Number of legal immigrants (thousands)
1,000
800
Great Depression
600
Figure 6.6: This graph shows legal immigration to the United States, 1820–2006 (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 certain illegal immigrants who could show they had been living in the country prior to January 1, (Data from U.S. Immigration and Naturalization Service and the Pew Hispanic Center)
400
200
Year
Fig. 6-6, p. 101

31. How does a population’s age structure affect its growth or decline?
Section 6-3
How does a population’s age structure affect its growth or decline?

32. A population’s age structure helps us to make projections
Age structure is the numbers or percentages of males and females in young, middle, and older age groups in a given population.

33. A population’s age structure helps us to make projections
Population age-structure diagrams are made by plotting the percentages or numbers of males and females in the total population in each of three age categories:
Prereproductive (0–14): normally too young to have children.
Reproductive (15–44): normally able to have children.
Postreproductive (45+): normally too old to have children.

34. A population’s age structure helps us to make projections
Demographic momentum is rapid population growth in a country that has a large percentage of people younger than 15, and happens when a large number of girls enter their prime reproductive years.
1.8 billion people will move into their reproductive years by 2025.

35. A population’s age structure helps us to make projections
Most future human population growth will take place in less-developed countries due to their population age structure.
The global population of seniors (age 65 and older) is increasing due to declining birth rates and medical advances that have extended life spans.

36. Generalized population age-structure diagrams

37. Less-developed Countries More-developed Countries
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
Active Figure 6.7: This chart represents the 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 significant potential for rapid population growth. See an animation based on this figure at Question: Which of these diagrams 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. 6-7, p. 102

38. CASE STUDY: The American baby boom
Added 79 million people to the U.S. population
The large numbers of baby boomers have strongly influenced the U.S. economy. First they created a youth market and are now creating the late middle age and senior markets.

39. CASE STUDY: The American baby boom
As the baby boomers turn 65, the number of seniors will grow sharply through This process has been called the graying of America.
As the number of working adults declines in proportion to the number of seniors, so will the tax revenues necessary for supporting the growing senior population.

40. The baby-boom generation in the US, 1955, 1985, and 2035

41. Populations made up mostly of older people can decline rapidly
Japan has the world’s highest % of elderly people and the world’s lowest % of young people.
Due to its discouragement of immigration, it may face a bleak economic future.

42. Populations made up mostly of older people can decline rapidly
The average age of China’s population is increasing at one of the fastest rates ever recorded.
This could lead to:
a declining work force,
higher wages for workers,
limited funds for supporting continued economic development, and
fewer children and grandchildren to care for the growing number of elderly people.

43. Populations can decline from a rising death rate: the AIDS tragedy
Between 1981 and 2010, AIDS killed more than 29 million people, and it takes about 2 million more lives each year (22,000 in the United States).
AIDS kills many young adults and leaves many children orphaned, causing a change in the young-adult age structure of a country.

44. Populations can decline from a rising death rate: the AIDS tragedy
This causes a sharp drop in average life expectancy, especially in several African countries where 15–26% of the adult population is infected with HIV.
AIDS can cause a pandemic loss of productive young adult workers and trained personnel.

45. 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 6.9: Rapid population decline can cause several problems. 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. 6-9, p. 103

46. Two projected age structures for Botswana’s population in 2020

47. Population (thousands)
–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
Age
Figure 6.10: Global outlook: Worldwide, AIDS is the leading cause of death for people ages 15–49. This loss of productive working adults can affect the age structure of a population. In Botswana, more than 24% of this age group was infected with HIV in 2008 and about 148,000 people died. This figure shows two projected age structures for Botswana’s population in 2020—one including the possible effects of the AIDS epidemic (red bars), and the other not including those effects (yellow bars). See the Data Analysis Exercise at the end of this chapter for further analysis of this problem. (Data from the U.S. Census Bureau) Question: How might this affect Botswana’s economic development?
Population (thousands)
With AIDS
Without AIDS
Fig. 6-10, p. 104

48. How can we slow human population growth?
Section 6-4
How can we slow human population growth?

49. There are three effective ways to slow population growth
The three most effective ways to slow or stop population growth are:
Reduce poverty
Elevate the status of women
Encourage family planning and reproductive health care.

50. The demographic transition

51. Birth rate and death rate (number per 1,000 per year)
Stage 1 Preindustrial
Stage 2 Transitional
Stage 3 Industrial
Stage 4 Postindustrial
Population grows very slowly because of a high birth rate (to compensate for high infant mortality) and a high death rate
Population grows rapidly because birth rates are high and death rates drop because of improved food production and health
Population growth slows as both birth and death rates drop because of improved
Population growth levels off and then declines as birth rates equal and then fall below death rates 80 70
Birth rate and death rate (number per 1,000 per year)
Total population 60
food production, health, and education
Birth rate 50 40 30
Figure 6.11: The demographic transition, which a country can experience as it becomes industrialized and more economically developed, can take place in four stages. See an animation based on this figure at CengageNOW. Question: At what stage is the country where you live?
Death rate 20 10
Low
Increasing
Very high
Decreasing
Low
Zero
Negative
Growth rate over time
Fig. 6-11, p. 105

52. Promote economic development
As countries become industrialized and economically developed, their populations tend to grow more slowly.
This demographic transition has four phases:
Preindustrial
Transitional
Industrial
Postindustrial

53. Promote economic development
Less-developed countries may transition to slower growth if modern technology can raise per capita incomes by bringing economic development and family planning.

54. Promote economic development
Rapid population growth, extreme poverty, and increasing environmental degradation in some low-income less-developed countries—especially in Africa—could leave these countries stuck in stage 2 of the demographic transition.

55. Empowering women can slow population growth
Women tend to have fewer children if they are educated, have the ability to control their own fertility, hold a paying job outside the home, and live in societies that do not suppress their rights.
Women account for 66% of all hours worked but receive only 10% of the world’s income and own just 2% of the world’s land.

56. Empowering women can slow population growth
Women make up 70% of the world’s poor and 64% of its 800 million illiterate adults.
Poor women who cannot read often have an average of 5–7 children, compared to 2 or fewer children in societies where almost all women can read.

57. Women of a village in Burkina Faso

58. Promote family planning
Family planning provides educational and clinical services that help couples choose how many children to have and when to have them.
Successes of family planning:
Without family planning programs that began in the 1970s, the world’s population would be about 8.5 billion instead of the current 7 billion.
Family planning has reduced the number of abortions performed each year and decreased the numbers of mothers and fetuses dying during pregnancy.

59. Promote family planning
Problems that have hindered success in some countries:
42% of all pregnancies in less-developed countries are unplanned and 26% end with abortion.
An estimated 201 million couples in less-developed countries want to limit their number of children, but lack access to family planning services.

60. Promote family planning
Quote from page 136:
“An estimated 215 million couples in less-developed countries want to limit their number of children and determine their spacing, but they lack access to family planning services. According to the UN, providing such services where they are needed would cost about $6.7 billion a year—about what Americans together spend on Halloween each year.”

61. CASE STUDY: Slowing Population Growth in India
For over 50 years, India has tried to control its population growth with only modest success.
The result: even though 9/10 Indian couples have access to at least one modern birth control method, only 48% actually use one.

62. CASE STUDY: Slowing Population Growth in India
Two factors help account for larger families in India.
Most poor couples believe they need several children to work and care for them in old age.
The strong cultural preference for male children means that some couples keep having children until they produce one or more boys.

63. Four of every ten people in India struggle to live on the equivalent of less than $1.25 /day