Man has existed on earth only for the last 50,000 years. It started from stone age some 20,000 years ago. About 6000 years ago the agricultural age started. Industrialization is about 200 years old only. After this the population growth has been very fast.
Study of human population statistically is known as demography. Demography as a cycle has five stages namely,
First Stage : Birth rate and death rate are quite high.
Second Stage : Death rate falls and birth rate is stationary.
Third Stage : Death rate goes on falling and birth rate also falls.
Fourth Stage : Death as well as birth rate both become low.
Fifth Stage : Birth rate becomes lower than death rate.
All over the world the rate of increase of population is not the same. In developed countries the growth rate of population is very low. In underdeveloped countries the birth rate is high.
Some Important Definitions
Sex Ratio : It is defined as the number of females per thousand males in a given ratio. In India it was 929 in 1991. Kerala has the highest number of women.
Birth Rate : It is the number of births in a year per thousand of middle aged population. It is called Natality.
Death Rate : It is defined as the number of deaths per thousand of population. It is called mortality.
World’s Population
Growth rate at present is about 2% per year. Total population in 1990 was 5 × 109. It has become about 6.35 × 109 in the year 2000.
Some Important terms
Biotic Potential : It is also known as reproductive potential. It is defined as the capacity of an organism to produce the offspring.
Environmental Resistance : It is defined as the resistance offered by environment or nature to control the population growth.
When the birth rate and death rate are equal, the population remains constant. In such a situation the growth rate is zero.
Carrying Capacity : Carrying capacity is the capacity of environment to carry the population. It is expressed by a constant.
Curves of Population Growth
Population growth is of two types—
(a) Exponential growth or J-shaped curve and
(b) Sigmoid or S-shaped curve.
(a) Exponential Growth Curve : If the birth rate is more than the death rate the population growth takes place. If the environmental conditions are good and favourable the growth rate becomes higher. The graph between population growth and time is J-shaped. It remains hypothetical because of the environmental resistance.
(b) Sigmoid Growth Curve : The growth rate is low when reproductive units are less in number. If food etc. is increased, growth rates become high. Growth rate becomes maximum because of low environmental resistance. Balance of population depends upon birth and death rate. This curve is S-shaped or sigmoid type.
Causes of Increase in Human Population
If the environmental resistance is absent the population grows in geometrical ratio when the food is given in arithmetical ratio. The causes of the growth of population are:
1. Better agricultural techniques.
2. Low death rate and high birth rate.
3. Low children mortality.
4. Early marriage.
5. Desire of a male child from social and religious point of view.
6. Lack of education which results in the non-adoption of family planning programmes.
7. Better protection from natural calamities.
8. Better food and medical facilities.
Results of population explosion : National growth has been hampered by the growth in the population. It has created socio-economic problems. Some consequences are as follows :
1. Poverty
2. Unemployment
3. Food supply deficiency
4. Educational problems
5. More unhygienic conditions
6. Increase in housing problem
7. Increase in pollution problem
Dynamics of human life with reference to economic aspect : The utlization of manimum population for the development and production of goods is known as economic development. Main aim of economic development is to increase the national production of all societies. Percapita income is defined as the gross national income divided by the national population. The higher is the per capita income the better is the standard of living of the people. For the betterment of living standards, the production of machinery, houses, education to the labourers, better working skills, capacity and health are required.
Economic development of a country requires the national saving.
Population increase and National income are closely related to each other. If population growth rate is high, then even high national income will not be sufficient to meet out the supply of essential commodities. Thus society will never get the benefits even if the national income becomes higher.
Population and standard of living : The higher standard of living of the society means bettter food, clothes, house, entertainment and luxurious facilities. Population growth adversely affects health services, food environment etc. In this way standered of living goes down.
In the developing countries present population growth rate is 2% to 3% which is directly affecting the social and economic development of the nations.
The growth of population is badly affecting housing facilities. The population living is unhygienic and the diseases are increasing. For increase in the development, more industries and more transportation facilities have to be developed. This is creating the environmental pollution problems thus disturbing the natural balance of environment.
Thus the increase in population growth rate the declines standard of living.
Population Control
The task of population control has been taken by World Health Organization (WHO) on priority basis. Due to higher population growth in India planning of national growth and development is badly affected. At present population of India is more than one billion.
The population can be controlled by following measures.
1. Raising of marriage age.
2. Education related to reproductive organs.
3. Use of family planning devices.
These devices are—
(a) Use of contraceptives : Contraceptive devices prevent the fertilization i.e. contact of sperm and egg. It can be divided into following :
Mechanical methods
(i) Use of condom : It prevents the contact of sperm and ovum.
(ii) Diaphragm : It fits over cervix and acts as a barrier against the sperm entry into uterus.
(iii) IUD (Intra-uterine devices) : Use of Copper T and loop, does not allow sperms to meet the ovum.
Chemical methods
(i) Jellies, foams and creams,
(ii) Oral pills—pills of sex hormones (estrogens and progesterones). They affect the ovulation and ova formation.
(b) Abortion : Medical termination of pregnancy.
(c) Sterilization : By surgical method so that ova and sperm passage is cut or discontinued. This is called vasectomy in case of man and tubectomy in case of woman.
(d) Natural methods
(i) Abstaining from intercourse.
(ii) Intercourse during safe period.
(iii) Withdrawal of penis from vagina before discharge.
Test tube babies : In some cases women are not able to give birth to a child. In such women the fertilization is not possible in the uterus but development of babies are possible in the uterus.
Test tube baby is an important advancement of medical science by which certain women can have children even if the fertilization conditions in the uterus are not feasible. The ovum of such woman is taken out. The fertilization process is completed in the laboratory with the sperms taken from her husband. The zygote thus formed is allowed to develop upto 32 cells stage. This embryo is implanted in the uterus of woman. This can develop into a normal child after a constant and regular professional care. Such babies are called test tube babies.
In very rare cases a surrogate mother may also be used to the development of fertilized (in vitro) egg and 32 cells embryo. Such an embryo is implanted and the birth of a baby is achieved. The production of such test tube baby has raised legal and ethical problems over the right of baby. However, the production of test tube babies has solved the problem of getting children.
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