These scholars based their statements and arguments on the trends in fertility and mortality, being experienced in Europe, North America and Australia. The theory postulates a particular pattern of demographic change from a high fertility and high mortality to a low fertility and low mortality when a society progresses from a largely rural agrarian and illiterate society to a dominantly urban, industrial, literate and modern society. The three very clearly stated hypotheses involved in the process are: (i) The decline in mortality comes before the decline in fertility; (ii) The fertility eventually declines to match mortality; and (iii) socio-economic transformation of a society takes place simultaneously with its demographic transformation. In the present-day world, as would be true of any point in time, different countries of the world are at different stages of the demographic transition. In the opinion of Trewartha, this is largely due to the dual nature of man. According to him, biologically, man is same everywhere and is engaged in the process of reproduction but culturally man differs from one part of the world to another.
It is the cultural diversity of man that gives rise to varying fertility patterns in different areas resulting in different stages of demographic transition. The demographic transition theory is characterized by conspicuous transition stages. The transition from high birth and death rates to low rates can be divided into stages. In the words of E.
G. Dolan, “Demographic transition refers to a population cycle that begins with a fall in the death rate continues with a phase of rapid population growth and concludes with a decline in birth rate”. Thompson and Notestein divided the process of transition into three stages whereas Sax has divided this transition period of population into four stages. Four Stages of Demographic Transition TheoryFollowing are the four stages of demographic transition: Stage I: High and fluctuating high birth and death rates, and slow population growth. Stage II: (Early Expanding): Stage of high birth rate and low death rate. Birth rate remains high; death rate falls; population begins to rise steadily. Stage III: (Late Expanding): Stage of declining birth rate and low death rate and slow population growth (growth rate of population declines). Stage IV: (Low Fluctuating): Stage of low birth rate, low death rate, and stationary population.
Population is steady.
In the first stage, the fertility is over 35 per thousand and the mortality is also high being more than 35 per thousand. The behaviour of mortality is, however, erratic due to epidemics and variable food supply. This stage, thus, postulates a stable and slowly growing population where the people are engaged in wasteful process of production.
This stage mainly occurs in agrarian societies with low or moderate population densities, low productivity level, high infant mortality, religious orthodoxy, lack of education and poor health care. In these societies large-sized families are considered as an asset. Consequently, life expectancy in low, the development of agricultural sector is at its infancy stage, masses are illiterate, technological know-how is lacking and urban development is limited. About two hundred years ago, all the countries of the world were at this stage of demographic transition. At present, it may be difficult to ascertain whether any country in the world would still be at this initial stage of demographic transition because the data pertaining to fertility and mortality for such areas would either be lacking or would not be reliable.
Moreover, the diffusion of modern technology has also been so fast, particularly in the field of medicine, that it is very difficult to find a solitary example of a country which may still be unaffected by the mortality declines taking place all over the world. It is in this context that the first stage has been called as the pre-industrial and the pre-modern stage.
The second stage of demographic transition is characterized by a high and gradual declining fertility of over 30 per thousand and a sharply reduced mortality rate of over 15 per thousand. In this expanding stage of demographic transition, while the improvements in health and sanitation conditions result in sharp declines in the mortality rates, the fertility maintains a high level, at least in the early second stage. As the second stage prolongs, the fertility also shows signs of gradual decline A distinction has often been made between the early second stage with high fertility and declining mortality and the late second stage with slowly declining fertility and sharply declining mortality. In the second stage, as a whole, the population expands, firstly, at a gradual increasing rate and afterwards at a gradual subsiding rate.
In the wake of population explosion associated with the widening gap between the two vital rates, the population and resource mobilization becomes significant. The life expectancy starts improving. The processes of industrialization, urbanization and modernization become prominent. The large families are no longer an asset. Consequently, the fertility undergoes a gradual decline leading to a gradual squeeze of rate of natural increase at the tail end of the second stage. Most of the less developed countries of the world are passing through this stage of demographic transition because of widespread penetration of modern medicines and sanitation measures have drastically reduced their mortality rates whereas their fertility rates are still high and hence a tremendous growth in population. The countries like India, Pakistan, Bangladesh, Nepal, Iran, Yemen, Kenya and Indonesia belong to the late second stage.
The third or the late expanding phase is characterized by a slowdown in the growth rate as the death rate stabilized at a low level and the birth rate declines with easy access to family planning methods.
This decline is associated with the growth of an educated urban/industrial society with low infant mortality, increased standard of living and changing status of women.
In this last stage of demographic transition, both birth and death rates decline appreciably. The population is either stable or grows slowly. In this stage, the population is highly industrialized and urbanized. The technical know-how is abundant, the deliberate controls on family size are common, the literacy and education levels are high, and the degree of labour specialization is also very high.
Anglo-America, West European countries, Australia, New Zealand, Singapore, Hong Kong and Japan are supposed to have reached this stage of demographic transition. Although the theory of demographic transition has been appreciated widely by the demographers, it has also been criticized on many counts. This theory is based upon empirical observations in Europe, America and Australia. Loschky and Wildcose asserted that the theory is neither predictive nor its stages are sequential and inevitable. For example, China has entered the third stage of demographic transition owing to the one child policy adopted by the government in the eighties. The role of man’s technical innovations cannot be underrated, particularly in the field of medicine which can arrest the rate of mortality. In spite of these shortcomings, the theory does provide an effective portrayal of the world’s demographic history at macro level of generalization. From such a model one should not expect that there would be a typical period of time for transition, a typical sequential of fertility and mortality patterns and a typical socio-economic fabric of each stage.
As an empirical generalization developed on the basis of observing the demographic trend in the West, the transition model does help in understanding the transition process for any country provided the situational context is properly understood. It would be academically unsound to expect all the countries of the world to follow the same sequential pattern as experienced by the European countries, because the present context is a significant deviation from the 19th century European context.