THE HUMAN POPULATIONCh. 9, Section 1: Studying the Human Population

Standards: SEV5a, b

WHAT IS DEMOGRAPHY? Demography- study of

populations, especially human populations.

Includes study of: Historical size of

population Make up of population Economics Social structure

Demographers use this info. to make comparisons & predictions about populations.

WHAT 2 CATEGORIES DO DEMOGRAPHERS GROUP COUNTRIES INTO?

1. Developed Countries

Have higher avg. incomes

Slower pop. growth Diverse industrial

economies Ex: US, western Europe

WHAT 2 CATEGORIES DO DEMOGRAPHERS GROUP COUNTRIES INTO?

2. Developing Countries

Lower avg. incomes Simple, agricultural

based economies Rapid population

growth Ex: India, China,

countries in Africa

HOW HAS THE HUMAN POPULATION CHANGED OVER TIME? Population grew slowly

for 1000’s of years In 1800’s (Modern Age)

population grew exponentially Due to increase in food

supply & better hygiene thanks to industrial & scientific revolutions

Human population continues to grow exponentially… will it ever reach its carrying capacity?

HOW CAN A POPULATION BE PREDICTED?

Demographers look at many properties of populations to predict: Will community need

more schools? Will community need

more retirement homes

Will population increase to point where we need more roads & utilities?

HOW CAN A POPULATION BE PREDICTED?

Demographers use numerous tools and graphs to predict populations: Age structure graphs Survivorship curves Fertility rates Migration patterns

AGE STRUCTURE GRAPHS Graph that shows the

distribution of ages in a specific population at a certain time.

A.K.A. population pyramids Parts of an age structure

graph: Bars = ages Colors = gender Numbers on bottom=

percentage of the population 3 Categories of Age

Structure Graphs Rapid growth Slow growth Declining/zero growth

AGE STRUCTURE GRAPHS

Rapid growth Young people

dominate population Has population

momentum- more children will move up to become reproductive

Rapid increase in birth rates once the youngsters reach reproductive age.

EX: Developing countries- many countries in Africa, Mexico, S. America

AGE STRUCTURE GRAPHS

Slow Growth Birth rates = death

rates All age groups are

about equal EX: Most Western

European countries, U.S.

AGE STRUCTURE GRAPHS

Declining Growth (Zero growth) Birth rates are lower

than death rates Many more older

people who are not reproducing

Fewer younger people Population will become

much smaller when they die.

Ex: Germany, Russia

SURVIVORSHIP CURVES

Percentage of members of a group that are likely to survive to any given age.

Follows a group of organisms from the time they were born to the time they die to see trends.

3 Types of Survivorship curves: Type I Type II Type III

SURVIVORSHIP CURVES

Type I Lots of offspring survive and

live to old age. Ex: Developed countries- US,

Japan Ex: Zebras, Bears, etc.

Type II Populations have a similar

death rate at all ages Ex: birds

Type III Lots of offspring die young &

very few survive to old age. Ex: Developing countries-

Africa, Asia Ex: insects, clams

FERTILITY RATES

Fertility rate- number of babies born each year per 1,000 women in a population.

Total fertility rate- avg. number of children a woman gives birth to in her lifetime.

Replacement level fertility- avg number of children each parent must have in order to “replace” themselves in the population. RLF = approximately 2 children

Compare Zambia to Europe using the chart to the right. What conclusions can you draw

based on this data?

Highest(Zambia)

Lowest (W. Europe)

Lowest (E. Europe)

Total Fertility Rate

6.7 1.3 1.4

GNP/capita/year

$225 $19,000 $3108

Life expectancy

47.6 yrs 77.6 yrs 68.9 yrs

Birth Rate per 1000

47.6 9.7 9.9

Death Rate per 1000

17.6 10.0 13.0

Infant Mortality Rate per 1000

120 7 22

Annual Growth Rate

2.9% 0.1% -0.4%

FERTILITY RATES

Keeping total fertility rate below replacement level fertility will help populations decline.

This graph shows US population change since 1920. Who are the baby boomers?

Lots of babies were born post WWII…when soldiers returned home from war ;)

Why did population start rising in the 1990’s? Children of baby boomers were growing up & having kids

MIGRATION PATTERNS

Immigration- movement into an area

Emigration- movement out of an area

US experiences lots of immigration… would our population decline if we didn’t have immigration?

WHAT FACTORS AFFECT A COUNTRY’S DEATH RATE?

Life expectancy- avg. number of years members of a population are likely to live.

Most affected by infant mortality- death rate of infants less than a year old.

Infant mortality (death rates) have decreased and life expectancy has increased due to access to adequate food clean water safe sewage disposal vaccines (around beginning of

20th century) access to education

Worldwide Infant mortality rates

WHAT FACTORS AFFECT A COUNTRY’S DEATH RATE?

Threats to life expectancy : As populations

increase, population becomes denser

Disease can spread quickly thru dense populations.

Ex: AIDS, tuberculosis

This will increase death rate and decrease life expectancy.

Sign located in South African village.

WHAT FACTORS AFFECT A COUNTRY’S BIRTH RATE?

Birth rates typically are lower in areas where: Women are educated

Academically Family planning techniques

Women are economically independent Have jobs So less time for raising

many children. Pensions are available for

elderly no need for kids to help

take care of elderly

WHAT FACTORS AFFECT A COUNTRY’S BIRTH RATE?

Large families are common when children are needed to work and take care of older family members

As countries modernize, there is less need for lots of kids.

This can decrease birth rates.

WHAT FACTORS AFFECT A COUNTRY’S BIRTH RATE?

Factors that can increase a population’s birth rate: Lack of birth control due

to availability or religion Need to have children

b/c have poor health care and children can die easily

Women are uneducated, repressed, with no rights to make decisions about their own bodies.

WHAT IS THE DEMOGRAPHIC TRANSITION?

Pattern of falling death rates & birth rates due to improved living conditions.

All countries should experience this trend in population change.

WHAT ARE THE STAGES OF DEMOGRAPHIC TRANSITION?

Preindustrial societies- Higher birth rates- due

to need for kids to help on farm; have lots of kids because many will die from disease/malnutrition.

Higher death rates- due to food shortages, malnutrition, lack of sanitation & medicine, accidents, other hazards

Population is low because of high death & birth rates.

WHAT ARE THE STAGES OF DEMOGRAPHIC TRANSITION? Industrialization-

Decreasing death rates- due to improved health care and sanitation.

Continuing high birth rates- people still having lots of kids because healthcare is not widespread and may be ignorant about birth control

People have better jobs, more income, more people surviving due to rise in standard of living.

Population grows exponentially.

WHAT ARE THE STAGES OF DEMOGRAPHIC TRANSITION?

Mature Industrial Death rates continue

declining Birth rates begin

declining Women realize they

don’t need as many kids

Women realize how expensive kids are

Women may have jobs so less time for kids

WHAT ARE THE STAGES OF DEMOGRAPHIC TRANSITION?

Postindustrial societies- eventually BR & DR level out & population is at equilibrium. W. Europe saw this in 19th & 20th century