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1.5 Population growth rates per annum, 2000-2008.
Demographic Transition Model
The rate of population increase in any area can be calculated by adding the rate of natural increase and the rate of
net migration. The natural increase in turn is the difference between the birth rate and the death rate. The birth
rate is the number of live births per 1000 people per year,
while the death rate is number of deaths per 1000 people
per year. If the birth rate exceeds the death rate, then the
total population size will increase as long as this natural
increase is not offset by losses due to migration.
Birth and Death Rates
Birth Rate
Total Population
High
Medium
Low
1
2
3
4
Death Rate
Time
1.6 The demographic transition model.
These changes are often analysed with reference to the
demographic transition model (figure 1.6). In this model,
a society passes through four stages. In stage 1, both birth
rates and death rates are high, so there is a small (if any)
increase in population size. Stage 1 societies are those
that are very traditional, such as might be found in isolated regions of the Himalayas, Irian Jaya, central Africa
and the interior of South America. Birth rates are high for
several sound, logical reasons. One important factor is
that the infant mortality rate is high and many children
die at a young age, so families often have additional children to compensate. Children are seen as economic assets
as they do useful work for the family from the age of six
1.7 In many countries, children are seen as an investment in the
family’s future. In countries where governments do not provide old
age pensions, children provide security for parents in their old age.
These children are with their father outside the family yurt in
Mongolia.
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Populations in Transition