ABSTRACT
Dramatic changes have occurred in terms of overall population in the world. The time it took for the earth’s population to reach the first billion spanned from Homo sapiens around 150,000 years ago to 1850. By 1930, it took only eighty years to reach the second billion; in the course of another thirty years, the third billion. Circa 1976, the world’s population reached four billion (Gordon and Snyder, 1986: 155). By 2005, the world population climbed to 6.5 billion people. This represents a gain of 76 million people annually and 380 million more than in 2000. By 2050, it is estimated that population will reach 9.1 billion people (World Population Prospectus, 2004). Because sex research, scholarship, and statistical evidence are generated continuously, readers are encouraged to update the data we present.
