Human Population and health disorder

 

Human Population

• Population is a group of individuals of same species that live in the same area at a particular time.

• The branch of population dealing with the scientific study of human population is called demography.

Census

• Census is an official count of the people of a country, state or district with statistic such as age, sex, education, employment etc.

• It is an extensive work & takes on every 10 years. Census help in planning the developmental programs.

Demography

• Scientific study of human population is known as demography.
• The persons who study the nature of human population change are

called demographers.

• Demography deals with five demographic processes namely fertility, mortality, marriage, migration and social mobility.

• These five processes continuously function within a population determining its size, composition and distribution. 

Demographic cycle

• Every nation has to pass through the following five stages of the demographic cycle.

1. First stage: both birth and death rate are extremely high.

2. Second stage: The death rate tends to fall but birth rate is stagnant.

3. Third stage: The death rate still keeps on falling and the birth rate is also tending to fall.

4. Fourth stage: Both death rate and birth rate are low.

5. Fifth stage: The birth rate becomes lower than the death rate. This stage lasts for a short period of time.

6. The rate of increase in natural population varies from one global area to another.

   • Growth rate is much lower in the developed countries than in the under-developed or developing countries.

7. 
   

8. Malthus theory of human population growth

   • Malthus, British political economist, put forward a theory of human population growth in 1978. He state that:

   1. Population multiplies in geometrical ratio where as food resources multiplies in arithmetic ratio.

   2. Faster growth of population than that of its requirements creates an imbalance between the two

   3. When the imbalance reaches to a certain limit malnutrition, epidemic diseases, war & environmental factors such as earthquake, flood, pollution etc reduce the population to a size the available resources can support.

      The factors that control the population size were called as positive checks by Malthus. 

   Definition of various demographic terms

   • Birth rate(Natality): It refers to the number of offspring produced per thousand unit of population per year.

   • Death rate(Mortality): It refers to the number of death per thousand of individual population per year.

   • Sex ratio: It is the ratio of male & female in a given population.