Demographic Theories- Biological, Social & Cultural | Anthropology Optional for UPSC PDF Download

Introduction

• Demography is the study of human populations their growth and decline due to changing patterns of migration, fertility and mortality and characteristics such as the sex ratio, dependency ratio and age structure.
• Demographic theories study the change in fertility and its effect on population growth. Different scholars gave biological, social and economic theories.

Biological Theories

• Diet theory - Thomas A. Doubleday: Thomas A. Doubleday gave his famous diet theory in his book: "The true law of population". According to him man's increase in population is inversely proportional to food supply. He says scarcity of food enhances fertility and surplus of food leads to decrease in fertility. He extends his theory to dietary habits. He says non vegetarians has less capacity to reproduce and vegetarians has high fertility rate. He also asserts that leanness is favourable to fertility. It is supposed that deposition of fat in the female reproductive tract reduces its contractility and prevents fertilization.
• Fertility function theory - Herbert Spencer: Herbert Spencer gave his theory in his famous book "The principles of biology" 1880. According to him preservation of species is general biological law governing population growth. There are two processes of preservation individuation and genesis. Individuation is linked to longevity and genesis is linked to reproduction.
  He maintained that lower forms of life have high genesis because there is low individuation whereas higher forms of life have low genesis because there is high individuation.
• Protein consumption theory - Jouse De Castro: According to him quantity and quality of protein consumption regulate fecundity. His theory states that less consumption of protein by females leads to high fertility. Less protein consumption leads to fatty degeneration of liver, causing it to become weak. A weak liver is unable to neutralize excess estrogen which circulates in high level and causes fertility to rise. So he suggested high intake of protein by females in reproductive age group to control fertility.

Socio-Cultural Theories

• Malthusian theory: According to him food grows in Arithmetic progression but population grows in geometric progression. The result would be gap in supply of food.
  To deal with this he prescribes two sets of checks: 
  (i) Positive checks - these are outside control if man like war, famine, diseases etc.
  (ii) Preventive checks - humans can control the growth of population with voluntary measures like late marriage, birth control, adultery etc.
  Criticism: 
  (i) Malthus geometric rise in population is not true for all populations but only for developing societies.
  (ii) Food production can be increased through technology like green revolution.
  (iii) Some of the preventive checks are unethical in nature. 
• Scientific theory of surplus population by Marx's: In capitalistic economic system labour gets a small share of wage compared to capitalist. As machinery increases unemployment increases then wage level of labour goes down and large population becomes surplus. Result of socially unjust practices of capitalism are poverty and hunger.
• Theory of social capillarity- A. Dumont 1890: Social capillarity governs fertility behaviour in civilized community. He assumed every society has hierarchic social order. For social mobility small family is favourable so lower social status people have less fertility. However this is not same in societies having rigid caste and social system like India.
• Theory of prosperity - L. Brentano: According to him a poor because of lack of alternative pleasures find compensation in sexual indulgence so there is high fertility. However rich man has alot of options for entertainment and pleasure so there is low fertility. This theory was critized as he did not differentiate the sexual enjoyment and pleasure of parenthood.

Economic Theories

Stages of Demographic Transition

• Cost benefit analysis of children- Harvey Liebenstein 1953: According to him there are three types of utilities of having an additional child.
  • Consumption good: source of pleasure for parents.
  • Productive unit: more children more income earning hands.
  • Source of security: for parents in old age.
    He says based on economic growth and income fertility decision changes. 
• Consumer durable model: Gary S. Becker 1960- " Economic analysis of fertility": According to him both children and household durable goods are identical. Consumer takes a rational decision based on taste, utility and cost. In the same ways number of children are decided based on requirement and expenses which occur on children.
• Theory of intergenerational wealth flow - J. C. Caldwell: According to him if wealth flow is more from parents to children then fertility would be less like in modern societies. But if wealth flow is more form children to parents then fertility would be more like in primitive societies.

Theory of Demographic Transition

• Demography is the study of human populations their growth and decline due to changing patterns of migration, fertility and mortality and characteristics such as the sex ratio, dependency ratio and age structure.
• Theory of Demographic transition is a recent one. This theory is more rational as it is based on demographic experience of many nations. A majority of economists and sociologists believe that population dynamics in any country pass through a series of stages with each stage having different characteristics.
• There are many contributors to this theory but Notestein in year 1945 gave its natural form. This theory proposes four stage sequence of birth and death rate which is associated with economic development.
  • First stage of demographic transition: According to this theory in first stage death rates are high as economy is agrarian and it has poor diets, primitive sanitation and absence of proper medical aid. The birth rates are also high because of illiteracy, lack of family planning, early age of marriage etc. As a result the actual rate of growth of population is low.
  • Second stage of demographic transition: In this stage the income level of people rise and as a result people improve their diet. Economic development of nation leads to development in all sectors like transport, medical facilities etc. All these factors lead to reduce death rate. But birth rate still remains high. As a result population growth and explosion takes place.
  • Third Stage of demographic transition: Economic development leads to industrialization and urbanization. This increases the standard of living which leads to literacy and size of the family reduces. Low birth rate and low death rate results in decrease population growth.
  • Fourth stage of demographic transition: Here both birth rate and death rate stabilize at low level. Many nations followed this economy growth and population growth was similar to as mentioned in this theory. By seeing the demographic transition graph of a nation we can guess their economic development.

Conclusion

Demographic theories aim to explain the changes in fertility and population growth based on various factors such as biological, socio-cultural, and economic aspects. Some prominent theories include Doubleday's Diet Theory, Spencer's Fertility Function Theory, Malthusian Theory, and the Theory of Demographic Transition. Each theory offers unique perspectives on how population growth is affected by factors such as food supply, social conditions, and economic development. The Theory of Demographic Transition, in particular, provides a comprehensive framework for understanding population growth in relation to economic development, with four distinct stages correlating to changes in birth and death rates. By studying these theories, we can better understand the factors influencing population growth and strategize policies to manage it effectively.