Demographic Transition Theory by Thompson and Notestein (1945) is based on fertility and mortality rates experienced by a population group and the changes in both these variables over time.
This theory has been refined and reformulated many times after 1945. As of today, the theory states that there are four stages in the demographic transition. These are :
1. High Fluctuating Stage (Stage 1):
The fertility (birth rate) is constant and high, while mortality is high but fluctuating due to epidemics, famine and war. Population growth is low as is the life expectancy while the infant mortality rate is very high.
2. The Early Expanding Stage (Stage 2):
The mortality rates decline while the fertility rates remain the same. The growth of population increases many fold along with life expectancy.
3. The Late Expanding Stage (Stage 3):
With passage of time, the social norms adjust to declining mortality and the birth rate also begins to decline. The percentage of young population increases. The growth rate begins to decline.
4. The Low Fluctuation Stage (Stage 4):
The fertility and mortality decreases to very low levels. Life expectancy rises and the percentage of middle aged and old population increases. This leads to a zero growth rate scenario as achieved by some developed countries. At times fertility dips below mortality leading to negative growth of population.
The decrease in die percentage of growth rate is a fair achievement but in real sense the population is still in a far from stabilizing state.
A very large proportion is under 40 years of age and still in the fertile state. The number of persons being added every year is also increasing. ‘We add an Australia every year to our population’.
On the basis of growth rate, the states and union territories of India can be divided into three categories:
1. Growth rate lower than National Average (21.34%):
Kerala, Tamil Nadu, Andhra Pradesh, Karnataka, Goa, Pondicherry, Orissa, West Bengal, Uttranchal, Himachal Pradesh, Punjab, Assam, Tripura and Lakshdweep.
2. Growth rate nearly same as National Average:
Maharashtra and Gujarat.
3. Growth rate higher than National Average :
Daman & Diu, Rajasthan, Haryana, Delhi, Jammu and Kashmir, Uttar Pradesh, Bihar, Sikkim, Jharkhand, Madhya Pradesh, Arunachal, Manipur, Nagaland, Mizoram, Meghalaya and Andaman & Nicobar Islands.
All the states in category 1 have higher levels of urbanization and literacy than the rest of the country.
Distribution of population refers to the spatial patterns in which the population is spread over an area. These patterns are explained by a set of physical, social, economic and political factors like – climate, soils, water, minerals, industry, transport and urban centres.
In India the distribution pattern has an overwhelming rural bias as 72% of the population lives in villages and is dependent on agriculture. Most of the population except in Kerala and Himachal lives in agglomerated settlements.
Unevenness of distribution is one of the typical features of India’s population. Among the states, Uttar Pradesh is the most thickly populated state and Sikkim is the most thinly populated state.
Among the Union Territories, Delhi emerges as the most crowded and Lakshdweep the least crowded. Along with Uttar Pradesh the whole Indo-Gangetic belt, comprising of Sutlej-Jamuna plains, Ganga plains and Brahmaputra plains emerges as thickly populated areas.
In addition to this, a belt of thick population lies in the delta region and the coastal areas of peninsular India, mainly in Malabar, Konkan and Coromandal coast. Another thickly populated region of South India is the Krishna – Godavari – Cauvery Valley region.
Other states showing relatively high and moderate agglomeration include the central, western and southeastern India and northern parts of peninsula. Some highly industrialized urban regions, distributed sporadically, also display high population.
By contrast the hilly states of Sikkim, Nagaland, Meghalaya, Manipur and Tripura in the north-cast and Himachal and Jammu and Kashmir in the north-west have the lowest population in the country.
Since the mainstay of India’s economy continues to be agriculture, the factors that govern distribution of population in the country are those that promote good agriculture, like the availability of cultivable land, depth of soil, fertility of soil, depth of underground water table, availability of water for irrigation etc.
The recently observed redistribution tendencies still reflect die hold of all such factors on die distributional pattern of Indian population.