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Demographic Transition Model and Population Pyramids
Transcript of Demographic Transition Model and Population Pyramids
At stage 1 the birth and death rates are both high, so the population remains low and stable. Places in the Amazon, Brazil and rural communities of Bangladesh would be at this stage. High death rates would be attributed to poor water supply, poor health care, a reliance upon subsistence farming, disease and pests and an unreliable economy. High birth rates would be attributed to a lack of knowledge of family planning, the need to have large families to help with work, and the women’s traditional role as a mother in these societies.
At this stage the death rate falls but the birth rate remains high. Natural increase is greater so the population begins to grow rapidly. An example of a country at this stage would be Sri Lanka or Peru. The death rates often fall due to medical breakthroughs and new hospital services opening. Improvements may have also been made to accommodation or food and water supply. Birth rates remain high for religious or cultural purposes and people are still not educated to using contraception.
Birth rates now fall and death rates continue to fall. Natural increase remains high and population growth is rapid. An example of a country at this stage would be Chile or China. The birth rates fall as there is better access to family planning and people have begun to appreciate the fact that families are expensive and that women are able to work. Death rates continue to fall as medical care, water supply and accommodation are improved.
Birth rates and death rates level out. The population now stabilises as the natural increase is low. An example of a country at this stage is Australia. Birth rates are low as the society is advanced and therefore, women choose for careers and smaller families to ensure that they have a better quality of life. Death rates remain low.
The model was designed to only incorporate four stages, however, in recent years there has been call for a fifth stage to be added to the model. At this stage the birth rate falls below the death rate and this result in a negative population increase. An example of a country at this stage is Japan. Japanese women are deciding that a career is more important than a family and many decide to not have children at all by being sterilised. Death rates remain low and the population begins to rapidly age.
A population pyramid illustrates the age and sex structure of a country's population and may provide insights about political and social stability, as well as economic development. The population is distributed along the horizontal axis, with males shown on the left and females on the right. The male and female populations are broken down into 5-year age groups represented as horizontal bars along the vertical axis, with the youngest age groups at the bottom and the oldest at the top. The shape of the population pyramid gradually evolves over time based on fertility, mortality, and international migration trends.
Uses and Limitations of the DTM
Why is the Demographic Transition Model useful?
•Its dynamic - it shows changes through time
•It describes what has happen in the UK
• USA and many other western countries have also been through the same stages
•Some countries are going through it at the moment - Newly Industrialised Countries, like South Korea
•Explains what has happened
•Explains why it happened in that particular sequence
•Based on western Europe
•Based on events from the past
•Its had to have been adapted since it was used – Stage 5 was added
•Not relevant to countries that aren’t industrialized
•Some LEDCs have imported medicine/sanitation techniques from MEDCs
•Does not give a timeline for how long it will take – 260 years for UK but South Korea seems to be rushing through in decades
•It doesn’t take migration rates into account
•Many factors affect death rate such as; famine, natural disasters, war.
•It doesn’t show Governments/Non-Government intervention
•Countries census data could be inaccurate
•DTM assumes all countries will go through stages in a certain order. Many countries in Africa seem to be in Stage 5 due to the HIV and Aids epidemic.
•It cannot predict what will happen in the future E.g. Natural disasters
Why doesn’t the pattern of Demographic Transition Model work for all countries?
The population pyramid for Australia is a convex shape wide base, with a narrow apex and a wide middle. This shows that the Australian population has a long life expectancy, their declining birth rates and low death rate show that they are in stage 3 of the DTM.
Once again, the population ramid for the USA is convex, but a slightly different shape: the population is stationary, because of a low birth rate, low death rate and long life expectancy. Therefore the US is in stage 4.
Unlike the first two nations, the pyramid for Brazil is concave due to high but declining birth rates, causing a wide base and a narrow apex. This shows a reasonably long life expectancy for a population that is between expansive and stationary, and thus in stage 3 of the DTM.
In China, there are declining birth rates, shown on this model by the wide middle, showing a population with more middle aged people, and, as with Brazil, the pyramid is concave, with a narrow apex, portraying a long life expectancy, and thus China is in stage 4.
Niger is a nation that is clearly in stage 1 of the DTM: it has a high birth rate, a high death rate, and this can be seen on the pyramid by the wide base and narrow apex which forms the concave shape of the pyramid. The rapid narrowing of the apex and rapid fall in the population of each upward age group shows the short life expectancy.