|The Evolution of Homo sapiens|
We cannot say exactly when fossils classified as H. sapiens first appeared; the precise point in time is a relative and arbitrary matter. However, the earliest H. sapiens may be from Africa at about 130,000 years ago. The "Mitochondrial Eve" hypothesis proposes an even earlier date for an African origin of modern humans. Modern H. sapiens may have been present in Asia as early as 115,000 years ago, and they were in Australia and Europe about 60,000 and 38,000 years ago, respectively. The only hominid populations found in Australia and the New World are classified as H. sapiens. Although considerably older dates have been proposed, firm dates for people in the New World go back only about 11,500 years.
Two models have been proposed to account for the appearance and spread of H. sapiens. According to the replacement model, modern H. sapiens evolved in a limited area, such as Africa, and then moved into other areas of the world; they completely replaced the Neandertals and other non-H. sapiens populations. On the other hand, proponents of the regional continuity model believe that the Neandertals contributed to the origin of modern Europeans while other populations evolved into H. sapiens in other geographical areas. Intermediate models see different degrees of interbreeding between archaic hominid and H. sapiens populations. By about 30,000 years ago, H. sapiens was the only type of hominid existing on earth.
Humans were exclusively foragers and scavengers for the vast majority of prehistory. About 13,000 years ago, domestication of plants and animals began in the Near East. Plant and animal domestication spread widely throughout the Old World; it was independently developed in the New World. In most parts of the world, the foraging way of life was gradually replaced by farming. A few foraging societies, however, still exist. In places where farming and raising animals occurred, settlement patterns changed - sometimes gradually - from nomadic to settled, and population size increased dramatically. Ultimately, the kinship-based organization of society was supplemented by government control. Cities arose to produce goods, to distribute these goods and farm products, and to ship excesses to other societies. Cities also served as religious and political centers. Writing, mathematics, science, and metallurgy became features of most developing civilizations. In addition, animals were "drafted" to do farmwork such as pulling plows. Eventually, beginning in the eighteenth century, human and animal power were joined by machine power, and the Industrial Age was born.