According to most archaeologists, human beings originated in Africa, and gradually spread from the continent to other parts of the world. Thus, the movement out of Africa was the initial migration in human history. The first human beings to come out of Africa settled in what is now the Middle East and Asia, gradually making their way to Europe and North America. This early stage of migration is thought to be responsible for all subsequent human migration, which proceeded through the Middle East, Europe and Asia.
When Europeans first settled in the Americas, they began to develop an interest in figuring out how the Native Americans arrived first. For years, this question went unanswered. However, starting about 60 years ago, anthropologists began to theorize that the first humans migrated to America from Asia by crossing an ice-age land bridge that would have existed in the Bering Strait between Russia and Canada. This bridge would have been comprised of earth that is now underwater, and would have last existed about 11,000 years ago.
The controversial Atlantic theory states that prehistoric human beings may have emigrated from Europe or The Middle East to the Americas by boat. This theory is not widely accepted by scientists, but it persists. The case for this argument is based on the fact that tools discovered in the Americas bear a resemblance to tools used by an early European people known as the Solutrean. This theory finds some additional support in the fact that Vikings were able to colonize parts of the Americas around the year 1000, traveling the Atlantic on relatively small and elementary ships.
Oceania theory links the people of Australia and Polynesia to the people of South America. According to this theory, people of Japanese origin migrated out of the East Pacific countries to South America, where they established early meso-American civilizations. Oceania Theory enjoys some degree of academic support, because a 10,000-year-old skeleton found in Washington State bears a facial resemblance to the Ainu peoples of Japan.