chapter 9

Chapter 9Chapter 9

Applying Population Ecology:Applying Population Ecology:The Human Population and The Human Population and

Its ImpactIts Impact

Chapter Overview QuestionsChapter Overview Questions

What is the history of human population What is the history of human population growth, and how many people are likely to be growth, and how many people are likely to be here by 2050?here by 2050?

How is population size affected by birth, How is population size affected by birth, death, fertility, and migration rates?death, fertility, and migration rates?

How is population size affected by How is population size affected by percentages of males and females at each percentages of males and females at each age level?age level?

How can we slow population growth?How can we slow population growth?

Chapter Overview Questions (cont’d)Chapter Overview Questions (cont’d)

What success have India and China had in What success have India and China had in slowing population growth?slowing population growth?

What are the major impacts of human What are the major impacts of human activities on the world’s natural ecosystems?activities on the world’s natural ecosystems?

Core Case Study: Is the World Core Case Study: Is the World Overpopulated?Overpopulated?

The world’s population is projected to The world’s population is projected to increase from 6.6 billion to 8.9 billion increase from 6.6 billion to 8.9 billion between 2006 and 2050.between 2006 and 2050.

The debate over interactions among The debate over interactions among population growth, economic growth, politics, population growth, economic growth, politics, and moral beliefs is one of the most and moral beliefs is one of the most important and controversial issues in important and controversial issues in environmental science.environmental science.


Much of the world’s Much of the world’s population growth population growth occurs in occurs in developing developing countries like China countries like China and India.and India.

Figure 9-1Figure 9-1


Some argue that the planet has too many Some argue that the planet has too many people.people.

Some feel that the world can support billions Some feel that the world can support billions of more people due to technological of more people due to technological advances.advances.

There is a constant debate over the need to There is a constant debate over the need to reduce population growth.reduce population growth. Must consider moral, religious, and personal Must consider moral, religious, and personal

freedom.freedom.

How Would You Vote?How Would You Vote?

Should the population of the country where you live Should the population of the country where you live be stabilized as soon as possible?be stabilized as soon as possible? a) Yes. Governments should use incentives and a) Yes. Governments should use incentives and

penalties.penalties. b) Yes. However, only through indirect means, like b) Yes. However, only through indirect means, like

education, or by relying on demographic transition.education, or by relying on demographic transition. c) No. The population of my country could continue c) No. The population of my country could continue

to grow without serious consequences. to grow without serious consequences.

HUMAN POPULATION GROWTH:HUMAN POPULATION GROWTH:A BRIEF HISTORYA BRIEF HISTORY

The human population has grown rapidly The human population has grown rapidly because of the expansion of agriculture and because of the expansion of agriculture and industrial production and lower death rates industrial production and lower death rates from improvements in hygiene and medicine.from improvements in hygiene and medicine. In 2006, the population of developed countries In 2006, the population of developed countries

grew exponentially at 0.1% per year. grew exponentially at 0.1% per year. Developing countries grew (15 times faster at Developing countries grew (15 times faster at

1.5% per year.1.5% per year.

Where Are We Headed?Where Are We Headed?

We do not know how long we can continue We do not know how long we can continue increasing the earth’s carrying capacity for increasing the earth’s carrying capacity for humans.humans. There are likely to be between 7.2-10.6 billion There are likely to be between 7.2-10.6 billion

people on earth by 2050.people on earth by 2050. 97% of growth in developing countries living in 97% of growth in developing countries living in

acute poverty.acute poverty. What is the optimum sustainable population of the What is the optimum sustainable population of the

earth based on the cultural carrying capacity?earth based on the cultural carrying capacity?

Where Are We Headed?Where Are We Headed?

U.N. world U.N. world population projection population projection based on women based on women having an average of having an average of 2.5 (high), 2.0 2.5 (high), 2.0 (medium), or 1.5 (medium), or 1.5 (low) children.(low) children.


FACTORS AFFECTING HUMAN FACTORS AFFECTING HUMAN POPULATION SIZEPOPULATION SIZE

Population increases because of births and Population increases because of births and immigration and decreases through deaths immigration and decreases through deaths and emigration.and emigration.

Instead of using raw numbers, crude birth Instead of using raw numbers, crude birth rates and crude death rates are used (based rates and crude death rates are used (based on total number of births or deaths per 1,000 on total number of births or deaths per 1,000 people in a population).people in a population).


Average crude and Average crude and birth rates for birth rates for various groupings various groupings of countries in of countries in 2006.2006.



The world’s 10 most The world’s 10 most populous countries populous countries in 2006 with in 2006 with projections in 2025.projections in 2025.


Declining Fertility Rates: Declining Fertility Rates: Fewer Babies per WomenFewer Babies per Women

The average number of children that a The average number of children that a woman bears has dropped sharply.woman bears has dropped sharply.

This decline is not low enough to stabilize the This decline is not low enough to stabilize the world’s population in the near future.world’s population in the near future. Replacement-level fertilityReplacement-level fertility: the number of : the number of

children a couple must bear to replace children a couple must bear to replace themselves.themselves.

Total fertility rate (TFR)Total fertility rate (TFR): the average number of : the average number of children a woman has during her reproductive children a woman has during her reproductive years.years.

Declining Fertility Rates: Declining Fertility Rates: Fewer Babies per WomenFewer Babies per Women

The replacement level to sustain a population The replacement level to sustain a population is 2.0 children.is 2.0 children.

In 2006, the average global Total Fertility In 2006, the average global Total Fertility Rate was 2.7 children per woman.Rate was 2.7 children per woman. 1.6 in developed countries (down from 2.5 in 1.6 in developed countries (down from 2.5 in

1950).1950). 3.0 in developing countries (down from 6.5 in 3.0 in developing countries (down from 6.5 in

1950).1950).

Case Study: Fertility and Birth Rates Case Study: Fertility and Birth Rates in the United Statesin the United States

Nearly 2.9 million people were added to the Nearly 2.9 million people were added to the U.S. in 2006:U.S. in 2006: 59% occurred because of births outnumbering 59% occurred because of births outnumbering

deaths.deaths. 41% came from illegal and legal immigration.41% came from illegal and legal immigration.


In 2006, the total fertility rate in the United In 2006, the total fertility rate in the United States was slightly > 2.0States was slightly > 2.0



The The baby bustbaby bust that followed the that followed the baby boombaby boom was largely due to delayed marriage, was largely due to delayed marriage, contraception, and abortion.contraception, and abortion.


Fig. 9-7, p. 176

47 years

Homicides per100,000 people

Hourly manufacturing job wage (adjusted for inflation)

Living insuburbs

Homes withelectricity

Homes withflush toilets

High schoolgraduates

Married women workingoutside the home

Life expectancy

1.25.8

$15$3

52%10%

99%2%

98%10%

83%15%

81%

2000

1900

8%

77 years

Factors Affecting Birth Rates and Factors Affecting Birth Rates and Fertility RatesFertility Rates

The number of children women have is The number of children women have is affected by:affected by: The cost of raising and educating them.The cost of raising and educating them. Availability of pensions.Availability of pensions. Urbanization.Urbanization. Education and employment opportunities.Education and employment opportunities. Infant deaths.Infant deaths. Marriage age.Marriage age. Availability of contraception and abortion.Availability of contraception and abortion.

Factors Affecting Death RatesFactors Affecting Death Rates

Death rates have declined because of:Death rates have declined because of: Increased food supplies, better nutrition.Increased food supplies, better nutrition. Advances in medicine.Advances in medicine. Improved sanitation and personal hygiene.Improved sanitation and personal hygiene. Safer water supplies.Safer water supplies.

U.S. infant mortality is higher than it could be U.S. infant mortality is higher than it could be (ranked 46(ranked 46thth world-wide) due to: world-wide) due to: Inadequate pre- and post-natal care for poor.Inadequate pre- and post-natal care for poor. Drug addiction.Drug addiction. High teenage birth rate.High teenage birth rate.

Case Study: U.S. ImmigrationCase Study: U.S. Immigration

Since 1820, the Since 1820, the U.S. has admitted U.S. has admitted almost twice as almost twice as many immigrants many immigrants and refugees as and refugees as all other countries all other countries combined.combined.


How Would You Vote?How Would You Vote?

To conduct an instant in-class survey using a classroom response To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main system, access “JoinIn Clicker Content” from the PowerLecture main menu for Living in the Environment. menu for Living in the Environment.

Should legal immigration into the United States (or Should legal immigration into the United States (or the country where you live) be reduced?the country where you live) be reduced? a) Yes: Because of threats of terrorism and the a) Yes: Because of threats of terrorism and the

burden on the economy, immigration should be burden on the economy, immigration should be reduced.reduced.

b) No. Humane efforts should be made to curtail b) No. Humane efforts should be made to curtail illegal immigration, but our economy needs legal illegal immigration, but our economy needs legal immigrants.immigrants.

POPULATION AGE STRUCTUREPOPULATION AGE STRUCTURE

The number of people in young, middle, and The number of people in young, middle, and older age groups determines how fast older age groups determines how fast populations grow or decline.populations grow or decline.

The number of people younger than age 15 The number of people younger than age 15 is the major factor determining a country’s is the major factor determining a country’s population growth.population growth.

Changes in the distribution of a country’s age Changes in the distribution of a country’s age groups have long-lasting economic and groups have long-lasting economic and social impacts.social impacts.


Populations with a large proportion of its Populations with a large proportion of its people in the preproductive ages 1-14 have a people in the preproductive ages 1-14 have a large potential for rapid population growth.large potential for rapid population growth.



32% of the people in 32% of the people in developing countries were developing countries were under 15 years old in 2006 under 15 years old in 2006 versus only 17% in versus only 17% in developed countries.developed countries.


Fig. 9-10a, p. 179

FemaleA

ge

Population (millions)

Developed Countries

Male

Fig. 9-10b, p. 179

FemaleA

ge

Population (millions)

Developed Countries

Male


Today, baby boomers make up nearly half of Today, baby boomers make up nearly half of all adult Americans and dominate the all adult Americans and dominate the populations demand for goods and services.populations demand for goods and services.



About 14% of the world’s population live in About 14% of the world’s population live in countries with stabilizing or declining countries with stabilizing or declining populations.populations.

Rapid population decline can lead to long-Rapid population decline can lead to long-lasting economic and social problems.lasting economic and social problems.

Death from AIDS can disrupt a country’s Death from AIDS can disrupt a country’s social and economic structure by removing social and economic structure by removing significant numbers of young adults.significant numbers of young adults.

Global again may help promote peace.Global again may help promote peace.


Age structure Age structure predictions based on predictions based on a medium fertility a medium fertility projection.projection.

The cost of an aging The cost of an aging population will strain population will strain the global economy.the global economy.



Some problems with Some problems with rapid population rapid population decline.decline.

Which of these Which of these problems do you problems do you believe are the most believe are the most important?important?


SOLUTIONS: INFLUENCING SOLUTIONS: INFLUENCING POPULATION SIZEPOPULATION SIZE

Demographic TransitionDemographic Transition: As countries : As countries become economically developed, their birth become economically developed, their birth and death rates tend to decline.and death rates tend to decline. Preindustrial stagePreindustrial stage: little population growth due : little population growth due

to high infant mortality.to high infant mortality. Transitional stageTransitional stage: industrialization begins, : industrialization begins,

death rates drops and birth rates remain high.death rates drops and birth rates remain high. Industrial stageIndustrial stage: birth rate drops and : birth rate drops and

approaches death rate.approaches death rate.


Generalized model of demographic transition.Generalized model of demographic transition. Some developing countries may have difficulty Some developing countries may have difficulty

making the demographic transition.making the demographic transition.Figure 9-14Figure 9-14


Family planning has been a major factor in Family planning has been a major factor in reducing the number of births and abortions reducing the number of births and abortions throughout most of the world.throughout most of the world.

Women tend to have fewer children if they Women tend to have fewer children if they are:are: Educated.Educated. Hold a paying job outside the home.Hold a paying job outside the home. Do not have their human right suppressed.Do not have their human right suppressed.


The best way to slow population growth is a The best way to slow population growth is a combination of:combination of: Investing in family planning.Investing in family planning. Reducing poverty.Reducing poverty. Elevating the status of women.Elevating the status of women.

SLOWING POPULATION GROWTH SLOWING POPULATION GROWTH IN INDIA AND CHINAIN INDIA AND CHINA

For more than five decades, India has tried to For more than five decades, India has tried to control its population growth with only modest control its population growth with only modest success.success.

Since 1970, China has used a government-Since 1970, China has used a government-enforced program to cut its birth rate in half enforced program to cut its birth rate in half and sharply reduce its fertility rate.and sharply reduce its fertility rate.

Fig. 9-15, p. 186

Total fertility rate

Percentageof world

populationPopulation

Population (2050)(estimated)

Illiteracy (% of adults)

Population under age 15 (%)

Population growth rate (%)

17%20%

1.1 billion1.3 billion

1.6 billion

IndiaChina

GDP PPP per capita

Percentage livingbelow $2 per day

Life expectancy

47%17%

36%20%

1.6%0.6%

1.4 billion

$5,890$3,120

4780

70 years62 years

2758

1.6 children per women (down from 5.7 in 1972)

Infant mortality rate

2.9 children per women (down from 5.3 in 1970)

India’s Failed India’s Failed Family Planning ProgramFamily Planning Program

Poor planning.Poor planning. Bureaucratic inefficiency.Bureaucratic inefficiency. Low status of women.Low status of women. Extreme poverty.Extreme poverty. Lack of administrative financial support.Lack of administrative financial support. Disagreement over the best ways to slow Disagreement over the best ways to slow

population growth.population growth.

China’s Family Planning ProgramChina’s Family Planning Program Currently, China’s TFR is 1.6 children per Currently, China’s TFR is 1.6 children per

women.women. China has moved 300 million people out of China has moved 300 million people out of

poverty.poverty. Problems:Problems:

Strong male preference leads to gender Strong male preference leads to gender imbalance.imbalance.

Average population age is increasing.Average population age is increasing. Not enough resource to support population.Not enough resource to support population.

HUMAN ASPECTS ON HUMAN ASPECTS ON NATURAL SYSTEMSNATURAL SYSTEMS

Excluding Excluding Antarctica, Antarctica, human human activities have activities have affect about affect about 83% of the 83% of the earths land earths land surface.surface.


HUMAN ASPECTS ON HUMAN ASPECTS ON NATURAL SYSTEMSNATURAL SYSTEMS

We have used We have used technology to alter much technology to alter much of the rest of nature in of the rest of nature in ways that threaten the ways that threaten the survival of many other survival of many other species and could species and could reduce the quality of life reduce the quality of life for our own species.for our own species.


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