This document discusses key concepts relating to world population growth including: - Demography is the statistical study of human populations and helps understand causes and consequences of population change. Accurate population data allows governments and businesses to plan. - The components of population change are births, deaths, and migration in or out of an area. Population change is calculated as births - deaths + immigration - emigration. - Birth and death rates are more significant measures than raw numbers. Canada's annual birth rate is 11 per thousand and death rate is 7 per thousand, resulting in 0.6% natural increase. - Human populations can grow exponentially as each generation reproduces. The "rule of seventy" estimates doubling time as 70 divided by

1. World Population Growth

2. • Demography – the statistical study of
human populations
• helps us to understand the causes and
consequences of population change
• - important because population can affect
government decisions – need accurate figures
of population change so that they can plan
for such things as numbers of schools and
classrooms that are needed in a community
• - businesses are interested in information
about family size, incomes, and consumer
habits as they plan their marketing
strategies.
•

3. Population Rates
• Components of population change are:
• • How many people are born
• • How many people die, and
• • How many move in or out of an area
• Population Change Equation:
• Births – deaths + immigrants (people
moving INTO country)
• – emigrants (people moving OUT OF
country)
• = increase or decrease in population

4. • Important:
• comparing the relationship between the #
of births and the size of the population in
each country is more significant that simply
comparing # of births. Demographers do
this by using measurements called birth
rates and death rates. Demographers use
rates per thousand when figuring population
change.
• Canada’s annual crude birth rate is about
11 per thousand, and the crude death rate
is about 7 per thousand, so the natural
increase is six per thousand – usually
expressed as 0.6 per cent.

5. The Rule of Seventy
• - human populations have the potential to
grow at an ever-increasing rate.
• Example: a couple has 4 children – who
have 4 children each – by the 3rd
generation
= 16 descendants
•
• - This is called an exponential rate of
increase – a rapid rate of increase as each
generation doubles in size
•
•

6. • - a convenient way to express exponential
population growth – is to use the length of
time it would take for a population to
double in size – can apply the “rule of
seventy”, which states that doubling time
(the period of years it takes a country to
double its population at its current birth
rate) is approximately equal to 70 divided
by the growth rate (in per cent)
• Example: Gabon’s present rate of
natural increase has a doubling time of
approximately 47 years:
•
• 70 divided by 1.5 (per cent growth per
year) = 46.7 years