Demography, the science of population, is basically concerned with the study of the size, distribution, characteristics, growth and structure of population over time. Demographic factor has been duly acknowledged by many a scholar as one of the important factors causing social change.
The following four areas fall within the domain of the study of demography: (i) To ascertain the total population within a prescribed geographical area. (ii)To ascertain as to whether the population in particular period or year has increased or declined as compared to a base period or year, (iii) To analyze the probable reasons for the increase or decline of population. (iv)To indicate, in the context of the aforesaid data, the future trend of population.
A change in population of any area depends on three factors or variables - (a) birth, (b) death, (c) migration. This may be put in the form of an equation:
P2 = P1 ± (Net increase/decrease) ± Net migration.
(In this equation, P1 = Population of the base year, P2 = Population of the year of comparison, Net increase/decrease = Birth rate - Death rate, Net migration = Immigration- Emigration)
Birth rate is a function of fertility, i.e. the actual reproduction of women. Demographers distinguish fertility from fecundity. The latter means the biological capacity to conceive and bear children. Usually, it covers women of the age-group 14-50 years.
Kingsley Davis observed, "Fertility, mortality and migration are all to a great extent socially determined and socially determining" We may, therefore, take note of the social factors which bear on fertility, mortality and migration. We may, therefore, take up the impact of demographic changes of society.
Social factors determining fertility:
Human fertility involves the physiological capacity of women and men to reproduce subject to individual choice and social control. Both individual choice and social control are, however, considerably affected by cultural factors, either negatively or positively. We may note briefly some of these factors.
(i) A society in which a couple is not supposed to marry until the husband is able to support a wife and family is likely to experience a lower birth rate and vice versa.
(ii) Birth rate depends on whether law of the land lays down the minimum age at which men and women are permitted to marry. Birth rate goes down if the prescribed minimum age is comparatively high.
(iii) Birth rate depends on whether the community adopts family planning as a way of life. If the community upholds values conducive to family planning, the birth rate is likely to be low and vice versa.
(iv) Birth rate depends on whether abortion or termination of pregnancy is or is not legally permissible.
(v) Fertility depends on whether society permits widow-marriage. Kingsley Davis has shown that this is one of main cultural factors responsible for lesser fertility among Hindus than Muslims in India.
(vii) According to an all-India-Sample Survey conducted in 1970 by Operations Research Group, only 13 percent of reproductive age couples with illiterate wives ever used any contraceptive method and the corresponding percentages were 29,43 and 72 among couples with primary-secondary and college educated wives respectively.
(viii) The theories linking economic development and fertility recognize that one main reason for high fertility in less developed countries is parents' expectations of support from their surviving children, especially sons, in their old age. The decline in such expectation is presumed to be one of the ways in which economic development reduces fertility.
(ix) The fertility level of a society may be related to its mortality level. A decline in morality eventually produces a decline in fertility. So far as decline in fertility is concerned, reduction of infant and child mortality seems to be more pertinent than other components of mortality. Many parents in developing countries depend heavily on children for old age security and as insurance against various kinds of potential risks. Since the degree of uncertainty regarding survival of children is high in many developing countries, "the most plausible response of parents is toward over-compensation for the loss of children. An actual reduction in infant and child mortality, accompanied by a perception of reduction in the degree of uncertainty, is expected to reduce fertility....."
The social and cultural factors affecting fertility, which are listed above, are only illustrative and not exhaustive. What is the implication of such a study? Fertility behavior of couples in every society is undoubtedly a matter of individual choice. But individual choice is influenced considerably by values and social institutions. In recent years, state intervention in fertility regulation in the form of state sponsored family planning programmes appears to be a very powerful agency whose influence will be felt in the years to come.
Social determinants of mortality:
Like fertility, mortality is also determined by social factors some of which are noted below.
(i) A high income at aggregate and individual levels is expected to cause decline in mortality because it facilitates increased consumption of items favorable to health, such as food and nutrition, medical and public health services, education, housing and leisure,
(ii) Provision of public health services is another important factor affecting mortality. "In developed countries the validation of the germ theory of disease in the late 19th century and its impact on public health practices and technology had a significant impact on subsequent mortality decline." Demeny, the demographer, is of the view that the application of modern techniques of public health control in less developed countries, independent of income level and distribution, is the main reason for the uniform trend in post-war mortality decline, A comparative study of mortality in Kerala and West Bengal shows that greater accessibility of health services in the rural areas of Kerala is one of the main reasons for lower mortality in that state.
(iii) Education has an important role in affecting mortality. The link between education and mortality may be stated thus. The education of mother is of crucial significance. "One possible mechanism is greater awareness among literate women about the need to use modern health facilities and consequently, higher utilization of the facilities by them than by illiterate women. Other mechanisms through which education affects mortality are perhaps by generating modern attitudes regarding health, disease, nutrition, personal hygiene and sanitation."
As in the case of fertility, so also in the case of mortality the factors effecting it, as listed above, are only illustrative and by no means, exhaustive.
Social determinants of migration:
Migration is a function of two kinds of factors: (i) Push factor which pushes people out of the country, resulting in what is generally known as emigration, (ii) Pull factor which attracts people into the country, resulting in what is called immigration.
Some of the factors which exercise either of these two kinds of influences are summarized as follows: (i) The prospect of better jobs or working conditions outside the country may push people out of the country while similar prospect in the home country may attract people from outside, (ii) Climate may be a factor influencing decisions of people either to go out or to come in. (iii) Religious or political persecution/freedom in a country may be a factor which influences the decisions of people either to go out of the country or to attract people of another country to come in. (iv) Law may influence migration directly. The host country may have immigration laws which may either encourage immigration or may serve as a deterrent.