Hanel, Germany J. Gathorpe-Hardy What do you think these cartoons are saying?
Demographic Transition Model
Population Change Births Immigrants Deaths Emigrants Total Population Natural Increase Migration The total population of an area is the balance between 2 forces of change: natural increase and migration Natural increase is the balance between birth rates and death rates Inputs Outputs
World Population Changes
Global Natural Increase
Average Annual Growth Rates
Doubling Time This map shows how long it will take for countries to double their population if it continued to grow at the present rate
Stage 1 High Fluctuating
Increasing very slowly
High birth rate
High death rate
Now? –tribes in remote Africa and Amazon - Sudan
Total Population Birth Rate Death Rate Stage 1
Stage 2 Early Expanding Total Population Birth Rate Death Rate Stage 2
Population growing at faster rate
High but decreasing birth rate
Decreasing death rate
Stage 3 Late Expanding Total Population Birth Rate Death Rate Stage 3
Population still increasing, but rate of increase slowing down
Decreasing birth rate
Low death rate
Stage 4 Low Fluctuating Total Population Birth Rate Death Rate Stage 4
High population, almost stable
Low birth rate
Low death rate
Is there a Stage 5? ? ? ? Stage 5: Depleting Population Sweden?
Demographic Transition Model Stage 1 Stage 2 Stage 3 Stage 4 Total Population Birth Rate Death Rate Ethiopia/ Niger UK: pre-1780 Natural Increase In Population Natural Decrease In Population Bangladesh/ Kenya UK: 1780-1880 Brazil/ China UK: 1880-1940 Japan/ USA UK: Post-1940
Demographic Transition Model and the Pyramids?
Reasons 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
Total Population Birth Rate Death Rate Stage 1
Reasons for Stage 2 Early Expanding Total Population Birth Rate Death Rate Stage 2
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
Reasons for Stage 3 Late Expanding Total Population Birth Rate Death Rate Stage 3
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
Reasons for Stage 4 Low Fluctuating Total Population Birth Rate Death Rate Stage 4
Rates fluctuate with ‘baby booms’ and epidemics of illnesses and diseases
Reasons for Stage 4 have improved and it stabilises
What problems do you think there could be with the model?
It does not include the influences of migration
It assumes that all countries will go through the same pattern
There is no time scale
Reasons for birth rates and death rates are very different in different countries
And finally, is there a stage 5?
Like all models, the demographic transition model has its limitations. It failed to consider, or to predict, several factors and events: 1 Birth rates in several MEDCs have fallen below death rates (Germany, Sweden). This has caused, for the first time, a population decline which suggests that perhaps the model should have a fifth stage added to it. 2 The model assumes that in time all countries pass through the same four stages. It now seems unlikely, however, that many LEDCs, especially in Africa, will ever become industrialised.
3 The model assumes that the fall in the death rate in Stage 2 was the consequence of industrialisation. Initially, the death rate in many British cities rose, due to the insanitary conditions which resulted from rapid urban growth, and it only began to fall after advances were made in medicine. The delayed fall in the death rate in many developing countries has been due mainly to their inability to afford medical facilities. In many countries, the fall in the birth rate in Stage 3 has been less rapid than the model suggests due to religious and/or political opposition to birth control (Brazil), whereas the fall was much more rapid, and came earlier, in China following the government-introduced ‘onechild’ policy. The timescale of the model, especially in several South-east Asian countries such as Hong Kong and Malaysia, is being squashed as they develop at a much faster rate than did the early industrialised countries. Like all models, the demographic transition model has its limitations. It failed to consider, or to predict, several factors and events: (cont..)
4 Countries that grew as a consequence of emigration from Europe (USA, Canada, Australia) did not pass through the early stages of the model.
T.R. Malthus, 1766-1834
English clergyman, Thomas Robert Malthus , was the first person to draw widespread attention to the two components of natural increase, births and deaths (fertility and mortality).
In his Essay on the Principle of Population , initially published in 1798, Malthus postulated that population tended to grow geometrically while the means of subsistence (food) grew only arithmetically. The Malthusian Trap arithmetic growth (food): 1, 2, 3, 4, 5, 6, 7, 8, 9, 10… geometric growth (population): 1, 2, 4, 8, 16, 32, 64, 128, 256, 512…
Malthus argued that the difference between geometric and arithmetic growth caused a tension between the growth of population and that of the means of subsistence. -- this gap could not persist indefinitely. Owing to war, disease, hunger, and vice, mortality would serve as a positive check on population growth.
BUT!!! Contrary to Malthus’s prediction, mortality has not yet risen to curb world population growth. < 1 billion people in 1800 6 billion by the end of the 20 th century
BBC REPORT – World Population to rise by 40% http://news.bbc.co.uk/1/hi/world/4297169.stm