The two principal migration theories of how humans arrived on the American continent, via the Beringia land bridge or as a result of trans-oceanic voyages, often conflict with the archaeological evidence of human habitation and settlement in North and South America. Archaeologists define human habitation as the presence of manufactured tools or a manipulated environment, such as quarries where stone tools were created. Unlike habitation, human settlement is defined as a change in identifiable subsistence patterns. For example, regular fish harvests, evidenced by the discovery of fishing tools, in proximity to depressions in the earth for dwellings suggest settlement. According to the archaeological record, human migration to the Americas occurred through many different means and over a vast period of time.

Human Habitation in South America

The oldest known dates for human habitation in the Americas are from sites in South America. The Monte Verde site in southern Chile has an occupation floor that is dated at 33,000 years ago. The tools at Monte Verde are of simple stone technology, but they indicate local environmental adaptation, not simply a variation of Siberian hunting technology. The degree of adaptation is significant because it indicates successful human occupation of South American coastlines for a considerable length of time.

Human Habitation in North America

The Bluefish caves in the Yukon contain evidence of migration and habitation by peoples from Asia to North America. Butchered mammoth bones, microblades with a wedge-shaped core, and trimming flakes of human manufacture were found by archaeologists Jacques Cinq-mars and William Irving. Unfortunately, earth shifts and geological disturbances have caused the site to contain no original cultural context. The significant element of this site was the discovery of a group of excavated bones, which were identified as horse remains. Horses were extinct from North America by the end of the late Ice Age. The Bluefish caves were located in a dry plain during glaciation, but were submerged 10,000 years ago, as part of the thaw that flooded Berginia. The horse bones were found next to human-manufactured stone tools, and the side-by-side placement of the two artefacts provide a date for the stone tools and the site (more than 10,000 years ago). Excavation continued and bone collagen from several animal fragments were discovered and dated at 15,000 to 12,000 years ago. The Bluefish cave site is significant not only because of the artefact dates, but because of the culture associated with the stone technology; the flaked tool technology excavated at the site was similar to tools of the Dyukhtai culture of Siberia.

Three archaeological sites in Alberta support the theory of a migration route through an Alberta corridor. Stone scrapers and choppers have been discovered at sites in Grimshaw, Bow River, and in Lethbridge. These stone tools were found under glacial sand and gravel are believed to be pre-glacial and therefore indicate humans occupied the area 20,000 to 40,000 years ago. The verification of the early dates, however, is dependent upon geological interpretation.

Human Settlement

The earliest evidence of human settlement in Canada is found on the Haida Gwaii (Queen Charlotte Islands) in British Columbia. The site at Nanu is dated beginning from 12,000 to 10,000 years ago. Ice age hunters and gathers left fluted stone tools and the remains of large butchered mammals. Nanu is unique because it is considered the site of the longest continuous human occupation in Canada.

The length and nature of human habitation and settlement is examined through linguistic studies, estimated population densities, and physiological evidence. These three areas of research expand upon the above-mentioned migration theories, and each one supports the hypothesis of three waves of distinct peoples migrating from Asia to North America.

Linguistic Studies

The development and diversification of language is a slow process but it reveals the length of time a group of people has been banded together. The greater the number of languages spoken in an area, the greater the length of occupation of those people in that area. The Pacific coastline is the site of the longest human occupation in North and South America because it contains the greatest proliferation of languages. Linguistic evidence supports the estimated date of human occupation in Monte Verde, Chile, at 33,000 years ago. The number of contemporary languages is compared with the highly subjective records of European explorers, and it is estimated that 2,200 distinct languages existed in North America at the time of European contact. These languages have been categorised into twelve general groupings by linguists.

Population Density Studies

Population and demographics are among the most difficult factors to measure of First Nations antiquity. Burial site excavations provide clues that archaeologists use to estimate death rates, and these are then correlated into population estimates. Another measure of population are the journals of European explorers. Although the journals are inaccurate, they do provide estimates of specific groups, such as the records of the Italian explorer John Cabot on the Mi'kmaq. Based on several sources, the North American population is estimated to have been around ten million in the fifteenth century. Population at the time of contact was concentrated along the Pacific coastline, where ten per cent of Canada's total population lived. Conservative estimates of the First Nations population in Canada during the sixteenth century are between 500,000 and 2,000,000.

Physiological Studies

Human migration patterns during North America's period of antiquity are difficult to decipher. Within world population groups, physical characteristics such as lineage, blood type, and dental analysis are related. The physiological characteristics of Amerindians, Aleut-Eskimo, and Dene peoples have been studied as a means of understanding where the North American populations originated. Scientists have collected physical, biological, and chemical information from North American Native groups with the intention of discovering whether or not these peoples are associated with cultures from other continents. The challenge of this type of genetic research in North America is the absence of a complete Pleistocene age skeleton. However, physiological evidence supports the theory of three waves of migration.

Physiological research has been subject to racial and prejudicial attitudes on the part of many nineteenth century European scientific theorists. Darwinism, translated and applied to humans, placed Western Europeans at the top of the evolutionary scale, whereas all other populations were rated 'developing societies'. Natives from North America were classified as primitive and low on the evolutionary scale.

Lineage

Using serological data to establish genetic diversity, biologists speculate that humans in North America originated from four maternal lineage groups. The frequencies of genes in blood groups were analysed to reveal historical biological affinities. An important aspect of the study was whether or not a linguistic grouping can be cross-referenced to a genetic grouping. This information has led to the theory of separate waves of migration into the Arctic, boreal forest, and the rest of North America.

Blood Type

Concentrations or lack of specific blood types in Amerindians are analysed to understand the origins and migrations of specific groups. 'A' and 'B' blood types are not found in Amerindian groups, with the exceptions of 'A' along the Pacific coastline and in the P Prairie regions. The percentage of 'A' blood type occurrence in the Blackfoot, Blood, and Peigan cultures is the highest in the world.

Dental Analysis

Christy Turner of Arizona State University uses dental morphology to speculate on settlement patterns in North America. His theory connects most of North American Natives to the mammoth hunters of the Clovis culture. He hypothesised that the sinodonts (incisor teeth), which all Native Americans have in common, are similar to sundadonts, which are in dental traits associated with Eastern Siberians. He has identified genetic similarities despite environmental evolution. Unfortunately, the skeletal record of North America is sparse, and acceptable samples are therefore difficult to locate.