The DTM describes how the population of a country changes over time. It gives changes in birth and death rates, and shows that countries pass through 5 stages of population change.
Links between the DTM and age structure (population pyramids)
The DTM can be used as a vehicle to demonstrate changes in population and can be incorporated into a pyramid to identify which stage a country is in or a pyramid can be used to identify which stage a country is in.
The pyramid indicates that Sudan has a high birth rate and a short life expectancy. This shows that Sudan is in stage one of the DTM because it falls into the stage one criteria.
The usefulness of the DTM
The DTM is useful because:
It is universal – it can be applied to all countries.
It provides a starting point for the study of demographic change over time.
The timescales are flexible.
It is easy to understand.
It enables comparisons to be made between the countries.
Relating the DTM to LEDCs/MEDCs.
Most MEDCs have passed through all of the stages.
At Stage 4 ny about the 1960s.
Some now moving to stage 5.
Took about 200 yrs to move through the stages.
Growth rates rarely exceeded 1% per year.
Economic growth led the transition.
Italy and Germany are in stage 5 – a population decline, where death rate has over took birth rate.
USA, Japan, France and the UK are in stage 4 – where birth and death rate are low however the birth rate is higher than the death rate.
Reasons for stages 4 and 5:
Birth rate - Family planning, good health, improving status of women, later marriages.
Death rate – Good health care. Reliable food supply.
Relating DTM to LEDCs/ MEDCs continued.
Not yet passed through all stages.
Many entered Stage 2 in mid 20 th century.
Many still in Stages 2 or 3.
Huge gap between birth and death rates – high population growth.
Population increase exceeds 4% per yr in some countries and 2% in others.
Moving through stages more rapidly.
Driven more by government policies and western medical aid.
Economic development lagging behind.
Egypt, Kenya – Stage 2 – High birth rate, lower death rate – rapid population growth.
Brazil, India and China – Stage 3- Falling birth and death rate, increase slows down.
Reasons for stage 2: Birth rate – Child labour, no family planning.
Reasons for stage 2 and 3: Birth rate – Improved medical care and diet. Fewer children needed. Death rate – Improvements in medical care. Water supply and sanitation, fewer children dying.