The People
It took 200,000 years for the number of people to reach the total of 545,000,000 estimated to have been in the world in 1650. In 1950, just 300 years later, there were an estimated 2,501,000,000, and by 1995 the number had risen to 5,716,000,000. In 1650 there were about 9 persons per square mile of land (3.5 per km 2 ); in 1995 there were about 109 per square mile (42 per km2).
Experts have described the world's "population explosion" as one of the most serious problems of the future. After World War II the average annual rate of population increase rose to about 2 per cent, roughly twice what it had been before the war. The greatest increases were in developing regions of Asia, Africa, and Central and South America.
Worldwide, the growth rate has dropped since the mid-1970's (it was 1.6 per cent a year in 1990–95), but it continued to rise in Africa (to 2.8 per cent). Several African nations had growth rates of 3 per cent or more.
In early times, before the development of transportation, people lived in small, scattered bands throughout the world. According to a generally accepted theory (here given in simplified form), each group gradually developed certain physical characteristics best suited for the environment in which the people of the group lived; as the environments differed, so eventually did the people, and the various races developed.
Anthropologists do not all agree on how to classify races. However, most classifications include these three broad categories as major races: Caucasoid, Mongoloid, and Negroid.
Each of the various isolated bands of people developed its own language. Languages are often classified into families, such as the Indo-European, to which English belongs; the Sino-Tibetan, which includes Chinese; the Malayo-Polynesian; the Japanese-Korean; the Dravidian of southern India and Sri Lanka; the Afro-Asiatic, including Hebrew and Arabic; and the Ural-Altaic, including Finnish and Hungarian. In addition, there are sub-Saharan African and American Indian language families.
