2. WHAT IS POPULATION ?
• Population is defined as a group of individuals belonging to the same
species ,
which live in a area of given time.
POPULATION DENSITY :
• It is expressed as the number of individuals of the population per unit
area
or per unit volume . This varies in response to changes in the
environment
and introduction with other living organism.
3. POPULATION GROWTH
The rapid growth of the global’s population for the past 100 years
results from
the difference between the rate of birth and death.
• In 1880, the global population was about 1 billion people . It took
about 130
years(in 1930) to reach 2 billion. But the population reached to 4 billion
within 45 years (in 1975). Now we have already crossed 6 billion and
may have
to reach about 10 billion by 2050 as per the World Bank calculations.
Increase in population = population growth
4. CHARACTERISTICS OF POPULATION
GROWTH
• EXPONENTIAL GROWTH : Now population growth occurs
exponentially
like 10,100,1000,10000 etc., which shows the dramatic increase in
global
population in the past 160 years.
• DOUBLING TIME : It is the time required for a population to double its
size
at a constant annual rate. It is calculated as follows
Td (Doubling time ) = 70/r
where, r = annual growth rate
If a nation has 2 % annual growth, its population will double in next 35
5. • INFANT MORTALITY RATE : It is the percentage of infants died out of those
born in
one year. Eventhough this rate has decreased in the last 50 years, the pattern
differs
widely in developing and developed countries .
• TOTAL FERTILITY RATES : It is the average number of children delivered by
a woman
in her life time. The TFR value varies from 2 in developed countries to 4.7 in
developing countries.
• REPLACEMENT LEVEL : Two parents bearing two children will be replaced by
their
off spring . Due to infant mortality this replacement level is changed. But, due
to high
infant mortality the replacement level is generally high in developing countries.
6. • MALE- FEMALE RATIO : The ratio of girls and boys should be fairly balanced
in a
society to flourish. But the ratio has been upset in many countries including
China
and India .China the ratio of girls and boys is 100: 140.
• DEMOGRAPHIC TRANSITION : Population growth is generally related to
economic development. The death rates and birth rates fall due to improved
living conditions. This results in low population growth. This phenomenon is
referred to a demographic transition.
8. CAUSES OF RAPID POPULATION GROWTH :
• Population growth is due to decrease of death rate and increase in birth
rate.
• Availability of antibiotics, immunisation , increased food production, clean
water and air
decreases the famine-related deaths and infant mortality.
• Agricultural based countries, children’s are required to help parents in the
fields that is why
population increases in the developing countries.
9. PROBLEMS ( ENVIRONMENTAL
ISSUSES ) OF POPULATION GROWTH
1) Increasing demands for food and natural resources.
2) Inadequate housing and health services.
3) Loss of agricultural lands.
4) Unemployment and socio-political unrest.
5) Environmental pollution.
• Causes of population growth :
1) Fertility rates.
2) International migration.
3) Increase in climate change.
4) Impact on biodiversity loss.
5) Overexploitation of resources.
10. METHODS OF POPULATION CONTROL
• The different methods of population control in human beings are
1) Child Tax,
2) One-Child Policy,
3) Sterilization,
4) Medical Abortion,
5) Family Planning, etc.
