Final answer:
Ancient people most likely traveled to North America by crossing the Beringia land bridge from Asia. Later migrations might have also involved maritime travel along the coastlines. These theories are supported by genetic and archaeological evidence, contrary to other less-accepted theories.
Step-by-step explanation:
Ancient Migration to North America
Ancient peoples likely traveled to North America by crossing a land bridge from Asia. This land bridge, known as Beringia, was exposed during the last ice age when sea levels were lower. The first inhabitants migrated across in search of food before the glaciers melted, which submerged Beringia and formed the Bering Strait. Genetic markers on a Y chromosome, shared by Asians and Native Americans, support this theory of migration. Subsequent settlers could have also used rafts or boats to travel across the strait or followed the coastline down to South America.
In addition to the Bering Land Bridge theory, the coastal migration theory suggests some peoples might have traveled by boats along the coastlines, potentially reaching South America before the North American interior was populated. This theory is supported by archaeological sites in South America that are older than those in North America and suggests maritime travel played a role in the spread of peoples throughout the Americas.
While the Beringia land bridge and coastal migration are the most accepted theories, it's worth noting that there are other theories too, such as the Solutrean hypothesis, which are more controversial and not widely supported by genetic evidence.