Population — Notes

Population explosion is a very rapid increase in the number of people in a short time.

The world: about 1 billion people around 1804, 2 billion around 1927, and 8 billion around 2022 (approximate UN milestones). The first billion took all of human history; the step from 7 to 8 billion took only about 11 years. The growth curve is J-shaped.

India (Census of India): 36.1 crore in 1951 and 121.1 crore in 2011; between 2001 and 2011 the population rose by about 18.2 crore (17.7 per cent). India has about 2.4 per cent of the world's land area but a far larger share of its people.

Main reasons

• Fall in death rate: vaccines, antibiotics, safer childbirth, more food, clean water and sanitation; fewer infant deaths and longer life expectancy.
• High birth rate: early marriage, illiteracy, little awareness of family planning, children seen as helpers and support in old age, desire for a son, social and religious customs.

The death rate fell quickly while the birth rate fell slowly, so the gap between them, the growth, became very large.

Demography is the statistical study of human populations: their size, density, distribution, births, deaths and migration.

Example: a town of 50,000 with 1,100 births and 400 deaths has a birth rate of 22, a death rate of 8 and a growth rate of 1.4 per cent a year. A district of 12,00,000 people on 2,500 square km has a density of 480 per square km.

Migration (people moving in or out) also changes the size of a population.

• Unemployment: the number of job-seekers grows faster than new jobs.
• Over-exploitation of resources: forests are cut, groundwater is over-pumped, soil is over-used, minerals and fuels are used up.
• Low per capita income: per capita income = total income ÷ population, so the same income shared by more people gives each less.
• Price rise: demand for food, housing and goods grows faster than supply.
• Pollution: more vehicles, factories, fuel, sewage and garbage pollute air, water and soil.
• Unequal distribution of wealth: the gap between rich and poor widens.
• Also: shortage of housing (slums), and crowded schools, hospitals and transport.

Need for control: to balance the population with land, water, food and jobs; to provide schools, health care and housing for all; to raise per capita income and the quality of life; to reduce pollution and the loss of forests. Education of girls, later marriage, awareness of the small family norm and family planning help to lower the birth rate.

Surgical (permanent) methods

• Vasectomy (men): a small piece of each vas deferens is removed and the cut ends tied. Sperms cannot pass into the semen. The testes go on making sperms and testosterone, so male characters are unchanged.
• Tubectomy (women): a small piece of each oviduct is removed and the cut ends tied. The egg cannot meet the sperms. The ovaries go on releasing eggs and hormones, and menstruation continues.

Both are chosen only by couples who want no more children, because the cut tubes are difficult to rejoin.