Population Composition

Population composition, or the demographic structure refers to those characteristics of population which are measurable and which help us distinguish one group of people from the other. Age, sex, literacy, place of residence and occupation are some of the important components, which reflect the composition of population. They also help in setting future agenda for development.

The age-structure of a population refers to the number of people in different age-groups. The size of the various age-groups does vary from one population to the other and also over the course of time. If the number of children in the population is high, the dependency ratio will be high. A large size of population in the agegroup of 15-59 years indicates the chances of having a larger working population. Similarly, a growing population in the age group of 60 plus indicates greater expenditure on the care of the aged. If there are large number of young people, and the birth rate is high, the population is youthful, as is the case in many developing countries of Asia, Africa and South America. On the other extreme, if the birth rate is low and the longevity among people is high, the population is said to be ageing.

This is happening in many European countries, the USA, Canada and Japan. At times, extreme events like wars, and natural calamities can distort the age-structure, because of losing population in certain agegroups. Generally, population of a country is grouped under three broad age-groups: Children (0-14 years); adults (15-59 years); and aged (60 years and above). Examination of age-group statistics of different parts of the world reveals that the proportion of adult population is least variable of the three groups. The major regional differences lie in the proportions of children and the aged.

On the basis of the variations, three types of age-structures have been identified :

• The West European Type: Children and the aged constitute 30 per cent and 15 per cent population respectively.
• The US Type : The proportion of children and the aged in the population are 35-45 per cent and 10 per cent respectively.
• Third World Type: Children constitute 45-55 per cent of population whereas the aged constitute only 4-8 per cent population.

Age pyramids give a more detailed picture of age structure. For this purpose, 5 or 10 years of age-groups are normally used. Each age-group of a population is represented by a horizontal bar, the length of which is proportional to the percentage of males and females in that age-group. Males are arranged to the left and females to the right of a vertical axis, which is divided either into single or multiple years or intervals. The shape of the pyramid can indicate the history and characteristics of the population portrayed. Thus three kinds of shapes are associated with three kinds of population situation:

• A Stationary Population : A regularly tapering pyramid shows unchanging birth and death-rates over a long period of time.
• A Progressive Population : A wide-base and rapid tapering shows an increasing birth rate and high death rate.
• A Regressive Population : A narrow base and narrow top pyramid shows declining birth rate and low death.

The age-structure of the world population reveals, the following characteristics:

• World population is more youthful with about 36 per cent population in the agegroup below 15 years. There are regional variations though as the corresponding figures for the more developed and the developing regions are 23 per cent and 40 per cent respectively. There is yet, wider variations at a lower level � continents and countries. The proportion of young population ranges from less than 25 per cent in Europe to about 40 per cent in Asia and Latin America and nearly 50 per cent in Africa. Countries that are characterised with high fertility rates have large proportions of young populations and the vice-versa. This age-group is economically unproductive and needs more money to be spent on food, clothing, education and medical facilities.
• The adult age group (15-59 years) is always higher than others, though it is proportionately more in developing countries. This group is biologically the most reproductive, economically the most productive and demographically the most mobile.
• Aged people (60 years and more) increases as the population of a country completes its demographic evolution. In the developed countries, the number of females in this age-group is more than that of the males. Increasing population of this age-group has more demands on health and social services.