1. The Demographic Transition Model (DTM)

2. Population Changes
The total population of an area depends upon changes in the natural increase and migration.
The natural increase (or decrease) is the difference between the birth rate and the death rate.
The birth rate is the number of live births in a year for every 1000 people in the total population.
The death rate is the number of people in every 1000 who die in a year.
If the birth rate is higher then the total population will increase. If the death rate is higher then the total population will decrease.

3. The Demographic Transition Model
The DTM describes a sequence of changes in the relationship between birth rates and death rates.
The model was produced using changes in the natural increase in several industrialised countries in western Europe and North America.
It suggests that the population growth rates for all countries can be divided into four stages

4. Demographic Transition Model
Total population
Birth rate
Death rate
BIRTHS AND DEATHS PER 1000 PER YEAR
Stage 1
Stage 2
Stage 3
Stage 4
TIME

5. Demographic Transition Model
Total population
Birth rate
Death rate
BIRTHS AND DEATHS PER 1000 PER YEAR
Stage 1
Stage 2
Stage 3
Stage 4
TIME

6. Stage 1 High Fluctuating
Low population
Increasing very slowly
High birth rate
High death rate
Ethiopia/Niger
UK: pre-1780
Birth Rate
Death Rate
Total
Population

7. Stage 2 Early Expanding Population growing at faster rate
High but decreasing birth rate
Decreasing death rate
Sri Lanka/Bolivia
UK:
Birth Rate
Death Rate
Total
Population

8. Stage 3 Late Expanding
Stage 3
Population still increasing, but rate of increase slowing down
Decreasing birth rate
Low death rate
Uruguay/China
UK:
Total
Population
Birth Rate
Death Rate

9. Stage 4 Low Fluctuating High population, almost stable Low birth rate
Low death rate
Canada/USA
UK: post-1940
Total
Population
Birth Rate
Death Rate

10. What do you think the reasons are for the changes at each stage?

11. Reasons for Stage 1 High Fluctuating
Little access to birth control
Many children die in infancy so parents have more to compensate
Children are needed to work on the land
Some religions encourage large families
Death rates are high due to disease, famine, poor diet, poor hygiene, little medical science
Birth Rate
Death Rate
Total
Population

12. Reasons for Stage 2 Early Expanding
Improvements in medical care
Improvements in sanitation and water supply
Quality and quantity of food produced improves
Transport and communications improve movements of food and medical supplies
Decrease in infant mortality
Birth Rate
Death Rate
Total
Population

13. Reasons for Stage 3 Late Expanding
Increased access to contraception
Lower infant mortality rates so less need for bigger families
Industrialisation and mechanisation means fewer labourers required
As wealth increases, desire for material possessions takes over the desire for large families
Equality of women means they can follow a career rather than just staying at home
Stage 3
Total
Population
Birth Rate
Death Rate

14. Reasons for Stage 4 Low Fluctuating
Rates fluctuate with ‘baby booms’ and epidemics of illnesses and diseases
Reasons for Stage 4 have improved and it stabilises
Total
Population
Birth Rate
Death Rate

15. Stage 5: Depleting Population
Is there a Stage 5? ? ? ?
Stage 5: Depleting Population

16. Stage I
Stage II
Stage III
Stage IV
High birth rates
Falling birth rates
Low birth rates
No or little Family Planning
Parents have many children because few survive
Many children are needed to work the land
Children are a sign of virility
Religious beliefs and cultural traditions encourage large families
Family Planning used
A lower infant mortality rates
Industrialization means less need for labor
Increased desire for material possessions and less desire for large families
Emancipation of women
Children as liabilities instead of assets
High death rates
Falling death rates
Low death rates
Disease and plague (e.g. bubonic, cholera, kwashiorkor)
Famine, uncertain food supplies and poor diet
Poor hygiene, no clean water or sewage disposal
Improved medicine
Improved sanitation and waters supply
Improvements in food production in terms of quality and quantity
Improved transport to move food
A decrease in child mortality

17. Geographical Variations
Developed countries
Took 250 years for most developed economies to go through their own demographic transition (from 1750 to 2000).
Population growth never surpassed the capacity of these economies to accommodate it.
Developing countries
Demographic transition started in the 20th century:
The most advanced segment after WWI.
The least advanced segment after WWII.
Very few have went trough the transitory mutation.
Most of them have a type III demographic transition.
By the time they reach type IV, a huge amount a population will be added to their populations.

18. Geographical Variations
Will demographic transition occur all around the world?
Model based upon the Western experience.
Evidence underline that the process is likely.
Problems:
The base population in the developing world is large.
Low percentages of population increase will result in large numbers of additional people.
Limited possibilities for immigration (Unlike Europe at the end of the 19th century and early during the 20th century).
Religious and cultural influences.

19. The model itself

20. Population structures
The rates of natural increase, births, deaths, infant mortality and life expectancy all affect the population structure of a country.
The population structure of a country can be shown by a population or age-sex pyramid.

21. Population pyramids show
The total population divided into five-year age groups
the percentage of people in each of those age groups
the percentage of males and females in each age group

22. Population pyramids are useful because they show:
Trends in the birth rate, death rate, infant mortality rate and life expectancy - these trends can help a country to plan its future services, e.g. more homes for the elderly if there is an ageing population or fewer schools if there is a declining birth rate.
The effects of people migrating into or out of a region or country.
The proportion of the population who are economically active and the proportion who are dependent upon them (dependency ratio).

23. Population pyramids