The question of how, when, where and why humans first entered the Americas is of intense interest to archaeologists and anthropologists, and has been a subject of heated debate for centuries. Several models for the Paleo-Indian settlement of the Americas have been proposed by various academic communities. Modern biochemical techniques, as well as more thorough archaeology, have shed progressively more light on the subject.
Current understanding of human migration to and throughout the Americas derives from advances in four interrelated disciplines: linguistics, archeology, physical anthropology, and DNA analysis. While there is general agreement that the Americas was first settled from Asia by people who migrated slowly across Beringia, over many generations, the pattern of migration, its timing, and the place of origin in Asia of the peoples who migrated to the Americas remains unclear.
In recent years, researchers have sought to use familiar tools to validate or reject established theories, such as Clovis first. As new discoveries come to light, past hypotheses are reevaluated and new theories constructed. The archeological evidence suggests that the Paleo-Indians' first "widespread" habitation of the Americas occurred during the end of the last glacial period or, more specifically, what is known as the late glacial maximum, around 16,500–13,000 years ago.