THE HUMAN POPULATION
Ch. 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?
Developed
Countries
1.
Have higher avg. incomes
 Slower pop. growth
 Diverse industrial
economies
 Ex: US, western Europe

WHAT 2 CATEGORIES DO DEMOGRAPHERS
GROUP COUNTRIES INTO?
Developing
Countries
2.




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 countriesAfrica, 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)
Total
Fertility
Rate
Lowest
(W.
Europe)
Lowest
(E.
Europe)
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
120
7
22
2.9%
0.1%
-0.4%
Infant
Mortality
Rate per
1000
Annual
Growth
Rate
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
Immigrationmovement into an
area
 Emigrationmovement 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
societiesHigher 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 ratesdue 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
societieseventually BR &
DR level out &
population is at
equilibrium. W.
Europe saw this in
19th & 20th century