The Demographic Transition Model (DTM)

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.

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

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

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

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

Stage 2 Early Expanding Population growing at faster rate High but decreasing birth rate Decreasing death rate Sri Lanka/Bolivia UK: 1780-1880 Birth Rate Death Rate Total Population

Stage 3 Late Expanding Stage 3 Population still increasing, but rate of increase slowing down Decreasing birth rate Low death rate Uruguay/China UK: 1880-1940 Total Population Birth Rate Death Rate

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

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

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

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

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

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

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

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

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.

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.

The model itself

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.

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

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).

Population pyramids