Demographic transition theory (DTT) is an attempt to capture the process of change from a situation of high mortality and high fertility to a situation of low mortality and low fertility. The demographic transition theory states that ancient society was marked by a high and fluctuating death rate. At that time survival of human society required that it reproduced at the highest level to counter the high force of mortality (caused by small pox, plague, malaria and other deadly infectious diseases, wars, natural disasters, shortage of food, violent conflicts and wars). If a year was free from natural catastrophes mortality was relatively lower and if there were outbreaks of diseases, wars, fire, famine or abnormal rainfall, then mortality was high. Demographers suggest that such a society may be placed in Stage I of demographic transition. In this stage the rate of growth of population fluctuates with a long run tendency to remain around zero. Module 5 has already thrown enough light on the nature of demographic transition in the world.
The theory says that as a society develops its death rate starts falling. The reasons are not adequately understood. Yet they include formation of nation state, improvement in working conditions, improvement in means of transport and communication, developments in the field of medical sciences and medicine, and improvement in income. Development of antibiotics and better surgical techniques have certainly played an important role in the reduction of death rate, though the role of socio-economic and political factors cannot be ignored. This reduction in death rate leads to a population explosion. Thus all Stage II societies experience rapid population growth. Finally, an equilibrium between birth and death rates is restored when couples start limiting the number of children. Thus in Stage III when death rates are low and birth rates are also low a zero population growth (ZPG) is restored. |
