During the first 2 million or so years of its history the human population was a minor element in the world ecosystem, with at most 10 million members. In the New Stone Age, less than 10,000 years ago, the number of humans began to increase more rapidly. The rough equilibrium maintained before Neolithic times gave way when the human population developed agriculture and animal husbandry and no longer had to spread out in search of game. With the abandonment of a hunting-gathering way of life and the rise of permanent settlements and eventually cities, the human population underwent dramatic growth. By the beginning of the Christian era it had reached 250 million, and by 1650, half a billion.

Growth of population during 20th century was very rapid. In 1994 the total world population was estimated at about 5.6 billion people. It increased nearly by 4 billions of people during past 100 years. The most significant world trend is that death rates are currently falling in poor and rich countries alike, while birthrates remain high in most poor countries and low in most rich ones. Exceptions are the generally higher death rates of Africa and the high birthrates of the rich oil-producing countries.

The most populous countries, in descending order, are China, India, the United States, Indonesia, Brazil, and Russia. The U.S. population totaled about 260.8 million in 1994. In the 1990s about 4.1 million children were born annually in the United States, and more than 2.1 million persons died yearly. The greater number of births is due in part to a fertility rate that has increased by nearly 20 percent since the mid-1980s. International immigration, both legal and illegal, is another major element in U.S. population growth. Legal immigration has recently amounted to about 1 million per year; illegal immigration is thought to be several hundred thousand. In China, the world's most populous country, the 1994 population was estimated at nearly 1.2 billion, more than double the 1953 census population of 584 million in mainland China. China's annual increase has been estimated at 1.1 percent annually. India's population of more than 911.6 million people (1994 est.) is increasing faster than that of China, and if present trends continue, it will soon catch up with or surpass China. Since the disintegration of the USSR, Indonesia and Brazil are now the fourth and fifth most populous countries, with 1994 estimated populations of 199.7 million and 155.3 million, respectively. Sixth-ranked Russia has about 147.8 million people (1994 est.). It has a negative natural increase rate of - 0.2 percent, comparable to the low or negative rates found throughout Europe. The arithmetic is simple. Our oceans can supply a limited amount of fish. Farm production is limited by the amount of available land. Once human demand for food, energy, and other materials exceeds sustainable levels, further increase in our population will mean that we each will get less and less and less. Today I will tell you about the most populated country in the world, China. Chinese population exceeds 1.1 billion people. 13% of people in China live in 52 major cities. City streets are often overcrowded with people, bicycles, cars, buses and other types of transportation. Most Chinese people live in the countryside. They plant rice and other crops, catch fish, and do many other jobs. Although there many people who live in the countryside, but work in cities. Chinese are very hard and good working people. Like you can see from the last paragraph, China is off to a good start, but its fast-growing population can stop China from achieving a high standard of living. China remains one of the worlds poorest nations despite its enormous gains in industry and agriculture since 1950. To control rapid population growth, the government launched a massive campaign the mid-seventies to encourage young people to marry late and to have few children. In 1980's, the government called for a target family size of three, and introduced many laws to limit number of children to one, in special circumstances, two. These measures helped to slow population growth dramatically. Nonetheless, China continues to have about 18 millions more new mouths to feed each year - a heave drain to its resources.