It was in a congenial environment created by biosphere’s relentless activity of more than 600 million years that man appeared on our planet barely one million years ago.

During the first 40-60 thousand years of his existence man lived as a scavenger, hunter and gatherer of food material. Under the circumstances, the ecosystem could support only about 10 million people. Nor could human activity cause much impact on the environment. About 50,000 years ago, the total world population has been estimated to be about 10 millions only.

The rapid growth of human population is mainly a result of rising food supply. Beginning of agriculture and domestication of animals marked the first step of mankind towards a civilized soci­ety. As a result the food production now rose to match the requirement of about 100 million people by 10,000 B.C. It was around this time that human settlements sprang up in fertile regions of the world.

For several thousand years following the development of settled life, human population re­mained well below the 250 million mark, which was crossed only about the time of Jesus the Christ. Within span of about 1650 years following the birth of Christ, the global population grew to about

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It was only in the twentieth century that growth of world population entered its exponential phase. This was made possible by a spectacular rise in food supplies. In 1930 A.D. it was two billion, in 1960 A.D. it was about three billion, in 1975 A.D. it was four billion, in 1987 A.D. it was five billion.

The world population is now growing at a rate of about 92 x 106 people per year and a slight decline in growth rate is expected in near future. However, most of the estimates of population growth predict a population of 6.12 billion in the year 2000 A.D., 8.2 billions in the year 2025 A.D. and more than 10 billion by 2075 A.D.

During the period from birth of Jesus the Christ to 1800 A.D., there was little refinement in agricultural technology and the rising human population was supported mainly by expansion of agriculture over the forested land. On the other hand, the population was limited by high mortality due to famine, diseases and wars.

Cholera, typhus, plague, small-pox, malaria, yellow-fever, sleep­ing-sickness, kala-zar etc. have been nature’s instrument to curb the size of human population. Av­erage life expectancy probably did not exceed 30 years even in the prosperous civilization of ancient India, Egypt, Greece and Rome (Dorn, 1962).

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From 18th century onwards, immunization, antibiot­ics, insecticides etc. coupled with great strides in communication, transportation and agricultural technology eased the pressure of heavy mortality. Life expectancy rose by about 5 years per decade during the current century. This has resulted in such a spectacular rise in human population during the twentieth century.