The demographic transition model (DTM)

Thedemographic transition model (DTM) descibes 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.

Stage 1 - high fluctuating - a period of birth rate and high death rate, both which fluctuate. Population growth is small. Reasons for the high birth rate include:

• limited birth control/family planning
• high infant mortality rate, which encourages the birth of more children
• children are a source of income
• in many cultures, children are a sign of fertility
• some religions encourage large families.

Reasons for a high death rate include:

• high incidence of disease
• poor nutrition and famine
• poor levels of hygiene
• underdeveloped and inadequate health facilities

Stage 2 - early expanding - A period of high birth rate but falling death rate. The population begins to expand rapidly. Reasons for the falling death rate include:

• improved public health
• better nutrition
• lower child mortality
• improved medical provision

Stage 3 - late expanding - A period of falling birth rate and continuing fall in death rate. Population growth slows down. Reasons for the falling birth rate include:

• changing socioeconomic conditions
• greater access to education for women
• preference for smaller families
• changing social trends and fashions, and a rise in materialism
• increased personal wealth
• compulsory schooling, making the rearing of children more expensive
• lower infant mortality rate
• the availabilty of family-planning systems, which are often supported by governments.

Stage 4 - low flucuating - A period of low birth rate and low death rate, both which fluctuate. Population growth is small and fertility continues to fall. There are significant changes in personal lifestyles. There are more women in the workforce, with many people havinghigh personal incomes and more leisure interests.

Stage 5 - decline - A later period, during which the death rate slighlty exceeds the birth rate. This causes population decline. This stage has only been recognised in recent years and only in some western European countries. Reasons for the low birth rate in this stage include:

• a rise in individualism, linked to the emancipation of women in the labour market
• greater financial independence of women
• concern about the impact of increased population numbers of resources for future generations
• an increase in non-traditional lifestyles. such as same-sex relationships
• a rise in the concept of childlessness
• the death rate may slighly increase because the population is ageing.

The DTM is useful because:

• it is a universal concept - it can be applied to all countries in the world
• 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 demographically between countries.

Limitation of the DTM are that:

• the original model did not include the 5th stage
• it is eurocentric and assumes that all countries in the world will follow the European sequence of socioeconomic chnages
• it does not include the role of governments
• it does not include the impact of migration

In the 1960's, it was noted that many countries of the more developed world had gone through the first four stages of the model. Countries of the less developed world seemed to be in a situation similar to stage 2 - the death rates had fallen but thier birth rates were still very high, leading to rapid population growth.

In the UK, as noted stage 2 took over 100 years to complete. This was because social, economic, and technological changes were introduced gradually and the death rate fell slowly. In many parts of the less developed world, the death rate has fallen much more rapidly because these changes, particularly the introduction of Western medical practices, have taken place more quickly. The birth rate, however, has stayed high and so the population has increased rapidly.

It was hoped that such countries would move into stage 3, as failure to do so could result in the population exceeding available resources. This was one of the reasons why China introduced the one-child policy, forcing its population into stage 3. Malaysia also reduced its birth rate by introducing a government-sponsored nationwide family-planning programme.

In summary, there are a number of important differences in the way that countries of the less developed and more developed world have undergone population change. In comparison with more developed countries, those in the less developed world:

• had generally higher birth rates in stages 1 and 2
• had a much steeper gall in death rates (for different reasons)
• had in some cases much larger base populations, so the impact of high population growth in stage 2 and the early part of stage 3 has been far greater
• in those countries in stage 3, the fall in fertility has been steeper
• had a weaker relationship between population change and economic development - governments have played a more decisive role in population management.