Population Pyramids : Meaning and Types
The age-sex structure of a population refers to the number of females and males in different age groups. An age sex pyramid or population pyramid is used to show the age-sex structure of the population. The shape of the population pyramid reflects the characteristics of the population and also indicates whether the population is experiencing growth or decline or stability.
In an age sex pyramid, the left side shows the percentage of males while the right side shows the percentage of women in each age group. By convention, the younger ages are at the bottom.
Triangle Shaped Pyramid
A Triangle shaped pyramid with a wide base reflects that the number of people with lower age groups is larger and thus there would be high birth rates.
This kind of age sex pyramid is typical for Nigeria, Bangladesh or Mexico or such less developed countries. These have larger populations in lower age groups due to high birth rates.
Bell shaped Pyramid tapered at top
Australia’s age-sex pyramid is bell shaped and tapered towards the top. This shows birth and death rates are almost equal leading to a near constant population.
Bell shaped Pyramid tapered at top and bottom
The Japan pyramid has a narrow base and a tapered top showing low birth and death rates. The population growth in developed countries is usually zero or negative.
India’s Age Sex Pyramid
India’s population is to grow by just over 57% between 2000 and 2050. This overall growth will, in part, be due to increased life expectancy and, therefore, a larger elderly population – around 10 million aged 80 years and over in 2005 to grow to around 50 million in 2050. However, the population is expected to begin to decline beyond 2050, with the 0-4 year old group falling from over 110 million in 2005 to just over 105 million. This means that India’s Age Sex Pyramid was on stage 1 in past and expected to be at stage 4 in 2050. Since 1981, India has been passing through the Third Stage of demographic transition. Few states and union territories of India already reached the fourth stage.
