Population composition

Population composition is the description of population defined by characteristics such as age, race, sex or marital status. Important characteristics of a population, besides its size and growth rate, are the way in which its members are distributed according to age, sex, and urban/rural status.These descriptions can be necessary for understanding the social dynamics from historical and comparative research. This data is often compared using a population pyramid.

Population composition is also a very important part of historical research. Information ranging back hundreds of years is not always worthwhile, because the numbers of people for which data are available may not provide the information that is important (such as population size). Lack of information on the original data-collection procedures may prevent accurate evaluation of data quality.

1. Age Structure:

The age structure of a population refers to the number of people in different age groups. A larger size of population in the age group of 15-59 years indicates the chances of having a larger working population. On the other hand, if the number of children in the population is high, the dependency ratio will be high. Similarly, a growing population in the age group of 60 plus indicates greater expenditure on the care of the aged.

There are three types of age structures, viz., (i) the West European type in .which children constitute less than 30 per cent, and 15 per cent of the population are old; (ii) the North American type where 35-40 per cent of the population are children and ten per cent, old people; and (iii) the Brazilian type where 45-55 per cent of the population are children, and old people constitute only four-eight per cent of the total population. The type of age structure has a direct influence on the future of a nation, since both extremes, i.e., old age dependency as well as young age dependency proves to be a severe burden on the economy of a country.

2. Sex Composition:

Another structural feature of populations is the relative numbers of males and females. Defined as the number of females per 1000 males in the population, sex ratio is an important social indicator of the equity prevailing between males and females at a given point of time. Factors influencing the sex ratio are, mainly, the differentials in mortality, sex selective migration, and sex ratio at birth and, at times, the sex differential in population enumeration.

By nature, slightly more males are born than females (a typical ratio being 105/106 males for every 100 females). However, males experience higher mortality at virtually all ages after birth. By implication, during childhood males outnumber females of the same age; the different decreases as age increases; at some point in the adult life span, the numbers of males and females become equal; as higher ages are reached, the number of females becomes quite large.

India shows an uneven composition of population as compared to most of the developed countries. The reasons put forward for such a state of affairs are: high maternal mortality, female infanticide, sex-selective female abortions, neglect of the girl child leading to a higher mortality among girls at a young age, and change in sex ratio at birth.

The sex composition of the population in India is a matter of concern, being much lower than 950 for a long time.

3. Rural-Urban Composition:

The division between rural and urban areas is significant in terms of geographical distribution of population. The percentage of rural population is higher in farm-based agricultural countries, while industrially, developed regions have higher share of urban population.

For a long time now, there has been a nearly universal flow of population from rural into urban areas. The most highly urbanised societies in the world are these of western and northern Europe, Australia, New Zealand, temperate South America, and North America: in all of these, the proportion of urban population exceeds 75 per cent.

In many of the developing countries of Asia and Africa, the urbanisation process has only recently begun; less than one-third of the population lives in urban areas. But the rate of growth of urban areas has shown a great increase. The general rule for developing countries is that the rate of growth of urban areas is twice that of the population as a whole.