Population Structure: Demonstrated visually by 2 models: Demographic transition Model and Population Pryramids

1. Demographic Transition (Population Change)
What do you need to know?
1. Population changes over time and space.
2. Population change can be shown on two
models.

2. Model 1: The DTM
(Demographic Transition Model)
Stage 1
Both high birth rates and death rates fluctuate in the
first stage of the population model giving a small
population growth (shown by the small total
population graph).

3. Model 1: The DTM
(Demographic Transition Model)
Stage 2
Birth rates remain high, but death rates fall rapidly causing a high
population growth (as shown by the total population graph).

4. Model 1: The DTM
(Demographic Transition Model)
Stage 3
Birth rates now fall rapidly while death rates continue to fall. The total
population begins to peak and the population increase slows to a
constant.

5. Model 1: The DTM
(Demographic Transition Model)
Stage 4
Both birth rates and death rates remain low, fluctuating with
'baby booms' and epidemics of illnesses and disease. This
results in a steady population.

6. Model 1: The DTM
(Demographic Transition Model)
Stage 5?
A stage 5 was not originally thought of as part of the DTM, but
some northern countries are now reaching the stage where total
population is declining where birth rates have dropped below
death rates.

7. Model 2: The PPM
(Population Pyramid Model)
The PPM - 'Population Pyramid Model' shows how dynamic
(subject to change) population is. The model is structured
to show 'snapshots' of a population at four points during
its development, which are shown as Stages 1 - 4 (A - D).
A country will progress through the stages.

8. High Fluctuating
Description
Reason
Wide base
High Birth Rate (poverty / tradition / high
Infant Mortality)
Concave shape
High Infant Mortality (poor Health Care /
sanitation / education / young mothers)
Narrow top
High death Rate (Poor health care / social
services for elderly)
Short
Low Life Expectancy (poverty/ education /
health care etc.)

9. Early Expansion:
Description
Reason
Wide base
High Birth Rate (poverty / tradition / high
Infant Mortality)
Less Concave shape
Decreasing Infant Mortality (Improving
Health Care / sanitation / education /
fewer young mothers)
Narrow top
High death Rate (Poor health care / social
services for elderly)
Taller
Improving Life Expectancy (reduction
poverty/ improving health care etc.)

10. Late expansion:
Description
Reason
Wide base
Population momentum (high numbers in
fertile ages mean large numbers of babies
despite lower growth rates.)
Convex shape
Low Infant Mortality (Good Health Care /
sanitation / education / family planning)
Wide top
Low Death Rate (Good health care / social
services for elderly)
Tall
High Life Expectancy (Less poverty/
education / nutrition / health care etc.)

11. Low Fluctuating
Description
Reason
Wide base
Population momentum (high numbers in
fertile ages mean large numbers of babies
despite lower growth rates.)
Convex shape
Low Infant Mortality (Good Health Care /
sanitation / education / family planning)
Wide top
Low Death Rate (Good health care / social
services for elderly)
Tall
High Life Expectancy (Less poverty/
education / nutrition / health care etc.)