POPULATION CHANGE
Chapter 16, Section 1
MEASURING POPULATION

Population= # of people living in a given
area at a time.


Demography= the area of sociology that focuses
on studying human populations.
Three factors affecting a region’s population:
Birthrate
 Death rate
 Rate of migration


Help determine how populations change over
time.
BIRTHRATE

Birthrate= births within a population
Live births/total population x 1,000
 Gives the number of births per 1,000 individuals.


Fertility vs. fecundity
Fertility # of births that actually occurred by
women of childbearing age.
 Fecundity measures those ABLE to have
children


Affected by various social, economic and health factors.
DEATH RATE

Mortality= number of deaths within a
society.


Death rate: Deaths/total population x 1,000
Death rates do not present an accurate picture of
a country’s conditions… so, sociologists also use
two other factors: infant mortality rate and
life expectancy.
Infant mortality rate= deaths among
infants/total live births x 1,000
 Life expectancy= average # of years a person
can expect to live.


There is a correlation between IMR and life
expectancy.

This helps determine the overall ‘health’ of a country.
MIGRATION RATE
Demographers also have to take into account the
migration of individuals when determining a
country’s population.
 Factors affecting migration:

Push factors religious or political
persecution; famine; discrimination;
overpopulation
 Pull factors additional freedoms; economic
opportunities; higher standards of living


Migration rate= annual difference between
in-migration and out-migration.
GROWTH RATE
The three variables affect the size of a
population.
 Rate at which a population is increasing=
growth rate.


Birthrate – death rate = growth rate.


Doubling time= amount of time it takes the pop’n to
double in size.
Negative vs. positive growth rates… is the
population growing or shrinking?

-
Practice calculating country growth rates.
http://www.os-connect.com/pop/p3n.asp
BR
DR
GROWTH RATE– ANSWERS

Brazil: 11.43 (population is growing)


China: 5.26 (population is growing)


Population grew 5%
Denmark: .09 (population is growing)


Population grew 11%
Population grew .09%
Which population is growing the fastest?
STUDYING A POPULATION

To examine the composition of a country’s
population, demographers (individuals who
study population) look at population
pyramids (also known as age-sex graphs).





Breakdown of population male/female
Percentage of the population each age group
comprises
Connect events to changes in population
Make assessments about overall health
Determine whether pop’n is growing or shrinking
EXPLAINING POPULATION CHANGE
Thomas Robert Malthus
 Malthusian Theory= population increases in a
multiplicative fashion, whereas food supply only
grows in an arithmetic progression.



Basically… The population is growing too
rapidly for the food supply to keep up.
Malthus proposed ‘checks’ on population.
Preventive checks birth control, sexual self-control
and delayed marriage and childbearing.
 Positive checks war, disease and famine.

MALTHUS (CONT’D)
But, Malthus could not foresee two coming
changes in society…
1) Advancement of agricultural techniques that
allowed farmers to produce more on same
amount of land
2) Birth control emerges as an effective and widely
used method.

DEMOGRAPHIC TRANSITION THEORY

Population patterns are tied to a society’s level of
technological development.


Three stages of a society’s population.
Stage 1
Preindustrial societies; high birthrate and death
rate.
 I.e. central African societies


Stage 2
Industrial societies; high birthrates and low death
rates (due to improved conditions)
 Guatemala and other Latin American countries


Stage 3
Industrial/post-industrial societies; low birthrates
and death rates.
 North America and Europe

DEMOGRAPHIC TRANSITION THEORY

Stage 4

Low birthrate, low death
rate, and increasing life
expectancy.


Approaching zero growth
rate= pop’n not growing or
shrinking.
Stage 5

Low birthrate (less than
in Stage 4), low death
rate, and increasing life
expectancy.

Population shrinking
CONTROLLING POPULATION GROWTH
Current world’s population: 7,315,737,000*
 Current U.S. population: 324,827,684*

* as of 10:40 am 5/18/2015

Two main strategies to control the world’s
population- family planning and economic
improvements
FAMILY PLANNING

Strategy used to lower the birthrate; occurs
when couples consciously decide to have a
certain number of children.


Helps reduce the number of unplanned pregnancies.
Antinatalism= strict form of family
planning involving official policies
designed to discourage childbirth.
In 1980, China adopted an incentive and sanction
system.
 Government benefits for those who adhere to one
child policy; large fines and penalties for those that
do not.

ECONOMIC IMPROVEMENTS
Better health, higher levels of income and access
to education will help lower birthrates.
 However, many impoverished countries do not
have the resources to provide this economic
assistance.

Demographers suggest evenly redistributing
wealth within a nation to help reduce poverty.
 Encourage limits on family size once basic needs are
met.
