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Wednesday, March 24, 2010

What is the Theory of Demographic Transition?

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The term ‘Demographic’ relates to the scientific study of populations and the term ‘Transition’ means- ‘the process and periods of changing from one state or condition to the other state or condition’. Thus, the Demographic Transition means- ‘The scientific study of the process or period of changes in a population from one state or condition to another state or condition.

An eminent demographer Frank Notestien outlined a theory which emerged out of his observations pertaining to the effect of economic and social development on the growth of population. His theory of demographic transition has provided the conceptual basis for demographic researches.

According to the theory of demographic transition, all the human societies may pass through any one of the three phases at a particular point of time. These phases are – First phase or Lag Phase, Second phase or  rapid growth phase, Third phase or Stabilization phase and the Fourth phase. The change over in population dynamics from one phase to the other is called as demographic transition.

Frank Wallace Notestein (August 16, 1902 - February 19, 1983) was an American demographer who contributed significantly to the development of the science. He was the founding director of the office of Population Research at Princeton University, and later president of the Population Council. He was also the first director of the Population Division of the united Nations, 1946-1948.According to Daniel Taylor an independent researcher, activist, and webmaster of oldthinkernews.com. – He “was one of the most influential population control activists and demographers of the 20th century. His work led to the establishment of demography as an academic discipline. He worked as the first director of the population division of the United Nations, was instrumental in the founding of John D. Rockefeller's Population Council in 1952, and was a director of population research at Princeton University.

In a paper written by Notestien in 1969 titled "The Problem of Population Control," he outlines a strategy of quickening the pace of depopulation. Notestien admits that economic modernization would "...bring the birth-rate down automatically." However, he goes on to state that more drastic measures must be taken because in his opinion this method would not be fast enough. "coercion" and the "institution of a totalitarian regime" are Notestein's solutions.

"...The need for an early reduction of the birth-rate is acute. Birth-rates in the past have fallen most rapidly in the context of modernization and social-economic change. But there is nothing in the European experience to suggest that we must rely solely on gradual and automatic changes in society. One often meets the glib generalization, particularly in the underdeveloped countries, that it is only necessary to concentrate on social and economic modernization since it is well known that we can rely on these processes to bring the birth-rate down automatically. The argument neglects the time-span required for such an adjustment... Even if we could be assured of rapid social and economic development the lag in transition between reduction of death rates and the reduction of birth rates poses enormous problems of population growth."

Notestien continues-
"...even if successful, voluntary family planning programs cannot be expected to resolve the world population dilemma. Even in the more developed countries, and notably in the United States, surveys show couples desiring more children than are necessary for replacement... Thus we cannot rely on the self-interested choices of individual couples to met society's needs. The only acceptable goal is zero rate of growth because any rate of growth continued long enough leads to astronomical figures. Given existing preferences in family size, governments must go beyond voluntary family planning. To achieve zero rates of population growth governments will have to do more than cajole; they will have to coerce."

"The logical target for legal and institutional pressures is the family: pressures to postpone marriages; economic pressures and inducements for married women to work outside the home; provision of free abortions for all women requesting them; downgrading of familial roles in comparison with extra familial roles; and restriction of housing and consumer goods... Such institutional changes supply motivation for family limitation and the provision of free abortions affords a means. The implications of such major institutional changes go far beyond population control. The family is the basic social unit of society and its major institution for the socialization of the children... to impose more drastic changes on a large scale implies many risks, not least to the regime that undertakes them. The price for this type of population control may well be the institution of a totalitarian regime."

According to this theory, high birth rates and high death rates to low birth-rates and low death rates are important parts of the economic development of a country from pre-industrial to an industrialized economy. This theory is usually described through demographic transition model (DTM) which describes population changes overtime.

The Demographic Transition Model involves four stages and these four stages are are summarised below-
(i).Birth rates and death rates are high in pre-industrial societies. Their population fluctuates rapidly according to natural events like drought, diseases etc. Thus relatively constant young population is produced.
(ii).The death rates drop rapidly in developing countries due to improvements in food supply, sanitation and healthcare facilities. It increases life spawn and reduces diseases. Countries in this stage experience heavy increase in population.
(iii).Birth rates fall due to contraception. This supports increase in wages, urbanisation, reduction in subsistence agriculture, an increase in the status and education of women and other social changes.
(iv).Both low birth rate and low death rates are observed in stage four. Low birth rates results in shrinking of population which is a threat to many industries that rely on population growth. Death rates may remain consistently low or increase slightly due to increases in lifestyles.Now that the birth rates have started declining, it appears that India has entered into the third stage of demographic transition since 1971.

Life -Tables
The statistics of mortality and life expectancy for different age groups of people in the population are represented by means of tables. These tables are called as Life- Tables. These are tables designed to evaluate how characteristics of population influence the overall growth rate of a population. Life Tables were originally developed by Insurance Companies to provide a means of determining how long any person of a particular age could be expected to live. Life Tables are also used by ecologists for plant, animal and microbial populations and for making projections about life expectancies. On the basis of life tables demographers and Ecologists plot Survivorship Curves. These curves represent number of individuals in a population that can be expected to survive to any specific age.

Uses of Life- Tables
Life tables are used for many different purposes like: (i) computation of average longevity of a population, (ii) representation of age-composition, (iii) indication of critical stages in the life cycle at which mortality is high, (iv)showing differences between species etc.

Key Words : demography, Frank Notestien,Lag Phase, rapid growth phase, stabilization phase, American demographer, demographic transition model,United Nations ,Ecologists plot Survivorship Curves,life- table. 

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