Population Structure Essay

604 Words3 Pages
Examine how population structure changes at different stages of the demographic transition model The demographic transition model has 4 main stages to it, also a stage 5 but very few countries have developed into this stage. The population structure changes for each stage showing the development of countries starting from stage 1 passing through 2, 3 and 4. The population structure for stage 1 of the demographic transition model has a low height, concave sides and uneven distribution of age groups. Birth rates are relatively constant and high but epidemics, famines and conflicts lead to fluctuations in death rates. These affect some age groups more than others in an erratic way. The structure is restricted to only a few of the world’s poorest people such as tribes in the Amazon Rainforest. In comparison to stage 1, stage 2 sees a broad base which progressively becomes smaller to form the steep not concaving sides. It also has a higher top but is still narrow. This shows that there are many children being born but they do not all survive and there is still a strong death rate. As a result, due to poor hospitals, medical care and famine, many people die at an early age and life expectancies are low. Few people manage to reach the age of 65. The spread of modern medical science and improvements in public health have led to a fall in death rate. The wide base of stage 2 reflects a remaining high birth rate due to the socio-economic conditions. Here the young make up the largest percentage and dominate the age structure. In some countries, such as Chad, the under 15 population make up to 50% of the total population. Stage 3 is the late expanding stage. In this population pyramid there us a narrower base as the birth rates are starting to decline. In stage 3 there is also a broader top as the life expectancy rises and the sides are slightly convex. Overall,
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