unit 3 a ch 9 s1 studying human populations
TRANSCRIPT
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