Population pyramids show the number of males and females within different age groups in the population. MALE FEMALE
Population pyramids may also be called age-sex pyramid and age structure diagrams. Population pyramids consist of two back to back bar graphs. Population is plotted on the X-axis and age on the Y-axis.
Males are nearly always shown on the left and females on the right. This can show the level of development in a country. There tends to be a larger number of females in the older age groups due to females having a longer life expectancy.
There are many different aspects of peoples life that affect how long they live for! Religion may also prevent the used of contraception. Educated about contraception and easily available. Less educated about contraception. Clean, readily available water. A limited, polluted water supply. A high level of medical care such as the NHS in the UK. Poor medical care. MEDC’s LEDC’S
All countries population pyramid will differ but 3 types have been identified by the birth and death rates of a country. Stable pyramids. Shows the unchanging pattern of birth and death rates. High birth rate; rapid fall in each upward age group due to high death rates; short life expectancy.
Expansive pyramids. High birth rate; fall in death rate. More people living in middle age and a slightly longer life expectancy. A population pyramid showing a broad base. A rapid rate of population growth, and a low proportion of older people. This is the typical pattern for less economically developed countr y.
Constrictive pyramids. A declining birth rate and a low death rate means the pyramid is top heavy. There is a larger percentage living to old age.
A baby boom! A baby boom is any period of time where there is a great increase in the birth rate. A baby boom is normally seen after a great war. This is because people feel the need to re-populate there country after the loss of men in the battles.
Thanks for watching Presentation by Robyn L Coe Picture from wikipedia.