Population Theories:
Demographic Transition
As you have noticed, family sizes have decreased over the most
recent generations in Canada. In fact, this is happening throughout
the world! Canada’s birth rate is 1.6 (2007).
Demographic Transition:
A country’s high birth rates and death rates changing
over time to low birth and death rates.
Population Pyramids
Comparing
Stage 1: Pre-Transition
● High birth rate & high death rate result in
*stable population (stayed the same)
● High infant mortality rate, few old people
● NO country in the world today is at this stage
Example: Sweden from 1740-1840 had stable
population...lots of births, but lots died from
diseases, wars, famines etc → evened out pop.
Pre-Transition Population Pyramid:
High Birth Rate, High Death Rate
Stage 2: Early Transition
● High birth rate and a falling (low) death rate
result in high population growth
● AKA: Population Explosion or Death Control
● High birth rate = children needed for food
and caregiver for aging parents; religious
teaching reject use of birth control
● This caused Earth’s population to rise from 1
billion in 1804 to 7 billion in 2008.
Stage 2: Early Transition Continued
Why Death Rate low?
● Water purification systems & vaccines
invented, disease control, advances in
medical technology
● Germ Theory: diseases too small to be seen
= wash hands, personal sanitation!! (19th
century doctors & nurses)
Early Transition Pop. Pyramid
Stage 3: Late Transition
● Declining birth rate and relatively low death
rate leads to a slowing population growth rate.
● Birth Control: families limiting children,
because more were now surviving (low infant
mortality rate from medical advances)
● Increasing number of old people
● Mothers working outside home, can’t raise big
family; children financial burden
Stage 4: Post Transition
● Low birth rate & low death rate = stable
population
● Many older people; “greying” society
Stage 5 ???
Declining population?
Extremely low Birth Rate?
Low Death Rate?
Fertility rate below 2?
Think about it:
*So, will the world every be over populated?
Underpopulated?
Homework
Different Ideas of Population Growth
Read 79 - 80
List differing ideas about population growth