demographic transition

Any change in birth and death rates; over time, these generally shift from a situation where both are high to a situation where both are low. This may be caused by a variety of social factors (among them education and the changing role of women) and economic factors (such as higher standard of living and improved diet). The demographic transition model suggests that it happens in four or five stages:

1) high birth rate, fluctuating but high death rate;

2) birth rate stays high, death rate starts to fall, giving maximum population growth;

3) birth rate starts to fall, death rate continues falling;

4) birth rate is low, death rate is low.

A fifth stage is thought to happen in developed countries where the population is aging, death rates exceed the birth rates, and the population declines.

In some industrialized countries death rate exceeds birth rate, leading to a declining population. The history of many European countries follows the demographic transition model, but in poorer countries the pattern is far less clear. A population pyramid illustrates demographic composition, and the Malthus theory gives a worst-case scenario of demographic change.