There are several popular
models of migration to the New World proposed by the
anthropological community. The question of how, when and why humans first entered the
Americas is of serious interest to anthropologists and has been a subject of heated debate for centuries. As new discoveries come to light, past hypotheses are reevaluated and new theories constructed.
The chronology of migration models is divided into two general schools of thought. One school believes in a “short chronology,” with the first movement into the New World occurring no earlier than 14,000 – 16,000 years ago followed by successive waves of immigrants. The “long chronology” camp posits that the first group of people entered the hemisphere at a much earlier date, possibly 20,000 years ago or earlier, and may have been followed by successive waves of immigrants.[1]
One factor fueling the debate is the discontinuity of archaeological evidence between North and South America. A more or less uniform techno-complex pattern known as Clovis appears in North and Central American sites from at least 13,500 years ago onwards. South American sites of equal antiquity do not share the same consistency and exhibit more diverse cultural patterns. Thus, many archaeologists conclude that the "Clovis-first" model does not adequately explain prehistoric tool complexes appearing in South America. Some theorists are seeking to develop a colonization model that integrates both North and South American archaeological records.
Also known as The Bering Strait Theory or Beringia theory, Land Bridge theory has been widely accepted since the 1930s. This model of migration into the New World proposes that people migrated from Siberia into Alaska, tracking big game animal herds. They were able to cross between the two continents by a land bridge called the Bering Land Bridge, which spanned what is now the Bering Strait, during the Wisconsin glaciation, the last major stage of the Pleistocene beginning 50,000 years ago and ending some 10,000 years ago, when ocean levels were 60&_160;metres (200&_160;ft) lower than today. This information is gathered using oxygen isotope records from deep-sea cores. An exposed land bridge that was at least 1,000 miles wide existed between Siberia and the western coast of Alaska. In the "short chronology" version, from the archaeological evidence gathered, it was concluded that this culture of big game hunters crossed the Bering Strait at least 12,000 years ago and could have eventually reached the southern tip of South America by 11,000 years ago.
