ABSTRACT
BASIC FACTS about POPULATION GROWTH The human race dates back about 3 million years. During more than 99 percent of this time there was virtually zero population growth. Average life expectancy was 20 to 25 years, and world population probably never exceeded 10 million people. After agriculture replaced hunting and gathering of food, around 6,000 to 8,000 B.C., population began to grow more quickly because larger numbers of people could be supported by food production. By the year 1 A.D., there were about 300 million people and, by 1650, 500 million.
