The demographic transition model

Overview

Demographic transition model and why the death rate falls before the birth rate.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is the demographic transition model, and what would the graph look like?

   Model answer

   It is a model showing how a country's birth rate, death rate and total population change over time as it develops, generalised from the recorded experience of countries that industrialised. The graph has time along the horizontal axis and rates per thousand per year up the vertical axis. Two lines are plotted, birth rate and death rate, both starting high on the left and both ending low on the right, with the death rate falling first. A third line, usually read against a separate scale, shows total population. The vertical gap between the birth and death rate lines at any point is the natural change, and shading it makes the population explosion of the middle stages obvious at a glance.

2. 2

   Describe stage 1 of the demographic transition model.

   Model answer

   Stage 1 is high fluctuating. Both rates are high, around 35 per thousand per year or more, and the death rate swings violently from year to year with famine, epidemic disease and war. Because the two rates are close on average, natural increase is very small, so the total population is high in relation to resources but grows only slowly and can fall back sharply. No country's national statistics are in stage 1 today; it describes pre-industrial societies and a very few isolated groups.

3. 3

   Describe stage 2 of the demographic transition model.

   Model answer

   Stage 2 is early expanding. The death rate falls steeply, perhaps from 35 to around 15 per thousand, while the birth rate stays high at about 35. The gap between the two lines is at its widest, so natural increase is at its maximum and total population climbs rapidly. The fall in deaths comes from improved and more reliable food supply, clean water, sewers and sanitation, better housing and basic medicine, and it is sharpest among infants and young children.

4. 4

   Describe stage 3 of the demographic transition model.

   Model answer

   Stage 3 is late expanding. Now the birth rate falls steeply, from around 35 towards roughly 16 to 18 per thousand, while the death rate continues to drift down more slowly and levels off at about 10 or below. The gap narrows, so the population is still growing but the rate of growth is slowing year by year. The fall in births reflects the spread of contraception, urbanisation, the education and employment of women, the rising cost of raising a child, and the fact that low infant mortality means fewer births are needed to end up with the same number of surviving children.

5. 5

   Describe stage 4 of the demographic transition model.

   Model answer

   Stage 4 is low fluctuating. Both rates are low, roughly 10 to 12 per thousand, and both fluctuate gently with recession, policy and fashion in family size. Natural change is close to zero, so the total population is high and roughly stable, and year-to-year change is driven more by migration than by births and deaths. The population is much older than in earlier stages, so the age-sex pyramid has near-vertical sides rather than a wide base.

6. 6

   What is stage 5, and why should you be careful with it?

   Model answer

   Stage 5 is a fifth stage added later to the original four-stage model, describing countries where the birth rate has fallen below the death rate — perhaps 8 against 11 per thousand. Natural change is negative, so the total population declines unless immigration makes up the difference, and the age structure is heavily weighted towards the elderly. Japan, Germany and Italy are usually cited. Be careful because the model as first published had only four stages, so some textbooks and mark schemes treat stage 5 as an extension rather than part of the model proper. Say which version you are using.

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