The Demographic Transition Model (DTM)

We are learning to… Describe how the population changes at each stage of the DTM Explain why birth and death rates change at each stage Give example of countries that fit into each stage

I Can… Interpret each stage of the DTM Give an account of the reasons behind the changes in birth and death rates at each stage Give examples of countries that fit each stage

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 five stages

The Model

Stage 1 – A high stationary population Both birth rates and death rates are very high Total population is very low Natural increase is low There are very few countries in stage 1 today – possibly only remote groups in the rainforest The UK was in Stage 1 before 1760

Stage 2 – An early expanding population Birth rates are still high Death rates are falling Total population is increasing Natural increase is high Some of the poorest developing countries are still in Sage 2 e.g. Malawi and Bangladesh The UK was in Stage 2 between 1760 and 1900

Stage 3 – A late expanding population Birth rates are falling Death rates are also continuing to fall Total population is increasing Natural increase is quite high Most developing countries are in Stage 3, such as Brazil. The UK was in Stage 3 between 1900 and 1950

Stage 4 – A low stationary population Birth rates and death rates are low Total population is steady Natural increase is very low Most developed countries are in Stage 4, such as the UK and USA. The UK has been in Stage 4 since the 1950s

Stage 5 – A declining population Death rates remain low Birth rates are low and decreasing Total population is decreasing Natural increase is negative Some developed countries are now in Stage 5, such as Australia and Germany

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

The age and sex structure of a country or area Population Pyramid USA 2010 Population in 5 year age bands Old Dependants Economically Active Young Dependants Usually, but not always in % to make for easier comparisons between countries Females to the right Males to the left

What Population Pyramids Show Us KEY Economically More Developed Country Economically Less Developed Country slope of pyramid indicate the death rate width of the base is related to birth rate/fertility rate proportions of men and women can suggest male or female migrations height of graph can indicate life expectancy (ignore the very thin end of the wedge as occurs on graph B as these people are a definite minority) "kinks" indicate dramatic reductions in birth rate or increases in death rate in the past area of graph indicates total population - compare areas of different population age groups or different sex on one graph The overall shape of the population pyramid can indicate whether it is an Economically More Developed Country or Economically Less Developed Country

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). Dependency ratio = (% children 0-14) + (%the ‘aged’ 65+) % economically active adults 15-64 X 100

Population pyramids in relation to the DTM

Task % population aged 0-14 % population aged 15-64 % population aged 65+ Dependency ration Comment Country A 15 66 19 Country B 44 51 5 Study the table above. Copy and complete the figures for dependency rations, then comment on your findings

Task Copy the following: The seven key points when describing and explaining a population pyramid Note the country and the date Note the horizontal axis: males usually to the left and females to the right Note the horizontal scale: % or raw numbers in millions Note the age cohorts (usually in five-year bands) Note the general shape Identify % in age cohorts. Suggestion - the young aged 0-14, the aged (usually 65+), the percentage of 85+. Then calculate the dependency ratio Look for gender differences, e.g. with the elderly, are there more women than men? Also are there more baby boys than girls?

Task Using the seven-point scale, complete your analysis of the population pyramids for China and Senegal