Population Growth Curves
The two main types of population growth curves are:
S-shaped growth curve is seen occurs when food supply ceases and growth
becomes stationary. It is applicable to bacteria, yeast cells, plants and
J-shaped growth curve is seen occurs when food supply ceases and mass
starvation leads to deaths.
J-shaped curve is applicable to human population in the absence of
Causes of Population Explosion in Human History
First population explosion
Change in culture and environment
Second population explosion (6,000 years ago)
Agriculture and farming
Third population explosion
Decrease in death rate
Modern medical facilities
Test Tube Baby
Test tube baby is produced when the ovum is fertilised
outside (in vitro fertilisation) but
development of the foetus takes place inside the
Durga is the name of the first test tube baby born
in India (Kolkata).
Density of a Population
Density refers to the total number of individuals in a population per unit
area at a specific time.
The density of a population is closely related to the size of the organism.
Smaller the size of an organism, greater is the density of organisms and
larger the size of an organism, lesser is the density of organisms.
Calculation of Density
The density of a population is calculated with the help of the formula given
D = n/a
D is the density of the population
n is the total number
of individuals in the population
a is the area in square kilometres.
The density of population in an area is determined by dividing the total
number of people living in an area by the area of land in which they live.
According to the Census of 1991, the density of human population in India was 267 per square kilometre.
Population is an assemblage of individuals of the same species occupying a
particular locality at a given time.
The change in the number and composition of a population influenced by one or
more factors at a given place at any given time is known as population
An increase in the number and size of the population is termed as positive
A decrease in the number and size of the population is termed as negative population
- The present rate of growth
of human population is about 2% per annum. In developing countries it is
2.5% per annum.
- Japan is the most thickly
populated country of the world.
- Australia is the most thinly
- Kerala is the most thickly
populated state of India.