HUMAN POPULATIONSThe Walker School

Environmental Science

Mr. Thomas Cooper

WHAT IS DEMOGRAPHY AND

WHY IS IT IMPORTANT?

Demography

The study of the vital statistics that affect population

size.•Size•Density•Age Distribution•Dispersion

World Population Clockhttp://www.census.gov/main/www/popclock.html

Demographic Statistics

Reproduction Rates

Infant Mortality Rates

Life Expectancy

Total Fertility Rate

Survivorship Curves

Life Histories / Tables

Life Expectancy at Birth of Epidemic Malaria Area in Papua New Guinea

Cohort Life Tables

An age-specific summary of the survival pattern of a

population.

Life tables are constructed by following a cohort from birth

to death.

A cohort is a group of individuals of the same age.

The table is constructed from the number of individuals that

die in each age-group during a defined time period.

Life tables are graphically displayed in survivorship curves.

Survivorship Curves

Type I

Type II

Type III

Life Histories Variables

Number of Reproductive Periods

Number of Offspring Each Reproductive Period

Gestation Time

Maturation Time

Size of Offspring

WHAT FACTORS AFFECT

HUMAN POPULATION

GROWTH?

Human Population Growth

World Population Growth Rate

1.25%

This adds 80 million people a year.

Population Growth Variables

Crude Birth Rate (CBR)

Crude Death Rate (CDR)

Immigration

Emigration

Density Dependant Factors

Density Independent Factors

Cultural Practices

Technology Revolutions

High

Medium

Low

12

11

10

9

8

7

6

5

4

3

21950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050

High

10.9

Medium

9.3

Low

7.3

Year

Po

pu

lati

on

(b

illio

ns)

UN World Population Projections

Crude Birth Rate for the World

Crude Death Rate for the World

Average crude birth rate Average crude death rate

World

All developed

countries

All developing

countries

Developing

countries

(w/o China)

21

9

11

10

24

8

29

9

© 2004 Brooks/Cole – Thomson Learning

Crude Birth and Death Rates

Poverty Affects Population Growth

Develop Countries Growth Rate 0.1%

Undeveloped Countries Rate 1.15%

Revolutionary Improvements

Increased food production

Better medical care

Improved sanitation

Industry-generated population centers

Information democracy

Current World Population Density

HOW LONG WILL IT TAKE FOR THE

WORLD’S POPULATION TO

DOUBLE?

Doubling Time – Rule of 70

Life expectancy/growth rate

70/1.25 = 56 years

Growth Rate Categories

Rapid (1.5-3%)

Slow (0.3-1.4%)

Zeros (0-0.2%)

Negative

Activity: Movie

Show PBS program

“World in the Balance”

in 20 minute segments

each day.

Have students answer

questions on handout for

each section.

WHAT ARE SOME KEY

INDICATORS OF POPULATION

GROWTH OR DECLINE?

Indicators of Population Growth or Decline

Natural Increase Rate (NIR)

Percentage by which the population grows in a year.

Total Fertility Rate (TFR)

Average number of children a women will have in her

lifetime.

Infant Mortality Rate (IMR)

Average number of infant deaths under 1 year of age,

compared with total live births

World Fertility Rates

Developed Countries = 2.1% World Average = 2.8%

Changes in US Fertility

32

30

28

26

24

22

20

18

16

14

0Bir

ths

pe

r th

ou

sa

nd

po

pu

lati

on

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Year

Demographic

transitionDepression

End of World War II

Baby boom Baby bust Echo baby boom

Factors Affecting Fertility and Births

Infant mortality rate

Average age at marriage

Ability of Legal Abortions

Availability of Reliable Birth Control Methods

Religious beliefs, traditions, and cultural norms

Importance of children as part of the labor force

Cost of raising and educating children

Availability of private and public pension systems

Urbanization

Educational and employment opportunities available for women

Importance of young adults joining the military

HOW CAN FAMILY PLANNING HELP

REDUCE BIRTH AND ABORTION

RATES?

Key Factors to Fewer Children

Ensuring education

Having jobs outside the home

Living in societies where their rights are not

suppressed

Family Planning Programs

Birth Spacing

Birth Control

Health Care for Pregnant Women

Heath Care for Infants

Room for Improvement

Need to expand programs to include teenagers

and sexually active unmarried women.

Need to emphasize abstinence.

Educate men about the importance of having fewer

children.

Pro-Life and Pro-Choice Groups to Join Forces

Condom

5%

Female sterilization

17%

IUD

12%

Other

methods

10%

Pill

8%

Male

sterilization

5%

No method

43%

Contraceptive

Use

MOST EFFECTIVE:1. Total Abstinence2. Sterilization3. Vaginal Implants

LEAST EFFECTIVE:1. Douche2. Chance

Condoms are “somewhat” EFFECTIVE

WHAT FACTORS AFFECT

DEATH RATES?

Life Expectancy at Birth

Factors Affecting Death Rates

Food Supplies and Distribution

Better Nutrition

Medical Advances in Vaccines and Antibiotics

Improved Sanitation

Safer Water Supplies

Economics and Life Expectancy

World Infant Mortality Rates

Infant Mortality Rates

Has dropped from 20 per 1000 births to 7 in

developed countries

Has dropped from 118 to 61 per 1000 births in

developing countries

Factors Still Affecting U.S. Infant Mortality

Inadequate health care for poor women during

pregnancy

Inadequate health care after birth for babies born

to poor women

Drug addiction among pregnant women

High teenage birth rate

Infant Mortality and Female Literacy

SHOULD THE U.S.

ENCOURAGE OR

DISCOURAGE IMMIGRATION?

Migration to U.S. by Region of Origin

Current Rate: 900,000 per year

Destination of Immigrants by U.S. State

Figure 12-14 (1)

Page 260

600

500

400

300

200

100

1900

19

20

19

40

19

60

19

80

20

00

20

20

20

40

20

60

20

80

21

00

76

273

571

Total population

Projections

Year

Po

pu

lati

on

in

millio

ns

Projected Population Increase in the United States

WHAT ARE AGE

STRUCTURE DIAGRAMS?

Age Structure Diagrams

Shows the distribution of various

age groups in a population.

A great deal of information about

the population broken down by

age and sex can be read from a

population pyramid, and this can

shed light on the extent of

development and other aspects of

the population.

Types:1. Stationary2. Expansive3. Constrictive

300 200 100 0 100 200 300

85+

80-85

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

Male Female

Population (millions)

Ag

e

Developed Countries

© 2004 Brooks/Cole – Thomson Learning

300 200 100 0 100 200 300

85+

80-85

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

Male Female

Population (millions)

Ag

e

Developing Countries

© 2004 Brooks/Cole – Thomson Learning

Teenagers and Pyramids

The number of people under age

15 is the major factor

determining a country’s future

population growth.

Population pyramids can be used

to find the number of economic

dependents being supported in a

particular population.

30% (1.9 billion) of people on

the planet were under 15 years

of age in 2004.

Ecomomic Projections

Who will need education

Who will need jobs

Who will determine markets

Who will affect elections

Who will need Medicare

Warfare Projections

Youth bulges argue that an excess in especially young adult male population

predictably leads to social unrest, war and terrorism, as the "third and fourth sons"

that find no prestigious positions in their existing societies rationalize their impetus

to compete by religion or political ideology.

HOW DO HUMAN POPULATIONS

DEVELOP ECONOMICALLY?

The Demographic transition model (DTM)

A model used to explain

the process of shift from

high birth rates and high

death rates to low birth

rates and low death rates

as part of the economic

development of a country

from a pre-industrial to an

industrialized economy.

Pre-Industrial Stage (Stage 1)

High birth and death rates

Low medical care (natural meds)

Population limited by food availability (internal)

Transitional Stage (Stage 2)

Increased food production

Better medical care (esp. antibiotics)

Improved sanitation (esp. drinking water)

Decreased death rate

Birth rate stays high (cultural norms)

Period of rapid growth rate

Industrial Stage (Stage 3)

Need for increased labor force

Availability of education (esp. female)

Delay in age of 1st reproduction

Change in cultural norms

Birth rates decline toward zero population growth

(ZPG)

Post Industrial Stage (Stage 4)

Industrial system no longer supports population

High unemployment, poverty

Food supplies diminish

Environmental health declines (high disease)

Social strife (disease, famine, war)

Increased death rates and decreased birth rates

Stage 5 ?

Countries that have undergone the economic

transition from manufacturing based industries into

service and information based industries called

deindustrialization.

Examples: United Kingdom (the earliest nation

universally recognized as reaching Stage Five),

Germany, Italy, Spain, Portugal, Greece, and most

Japan.

HOW CAN WE ACHIEVE

POPULATION STABILIZATION?

Achieving Population Stabilization

Increase the amount of money that they allot to public health and family planning

Increase the average level of education, especially of women

Increase the employment opportunities for women

Decrease consumption by developed nations