Final answer:
Humans migrated from Siberia to Alaska across the Bering land bridge, known as Beringia, following Pleistocene megafauna. The coastal migration route, or kelp highway hypothesis, indicates travel by boat along the continental shelf. The Bering Land Bridge theory is widely accepted for the peopling of the Americas, while alternative theories, like the Solutrean hypothesis, have less support.
Step-by-step explanation:
During the last ice age, approximately 50,000-10,000 years before the present (BP), humans migrated from what is now Siberia to Alaska using a land bridge known as Beringia. This land bridge emerged due to low sea levels caused by the formation of massive glaciers around the world. It is speculated that there were as many as four distinct migrations during this period, with people following the megafauna of the Pleistocene, such as mammoths and mastodons.
Additionally, the kelp highway hypothesis suggests a coastal migration route, where early populations from northeastern Siberia may have traveled by boat, following a rich food source along the continental shelf. Substantial evidence of human presence in the Americas dating to about 10,000 years BP supports the coastal migration theory, with archaeological sites found in coastal Alaska and Canada, reinforcing the belief in this model of migration.
The Bering Land Bridge theory remains the most widely accepted model for the migration of peoples to the Americas. However, alternative theories, such as the Solutrean hypothesis, suggest European origins for the Clovis peoples. These are considered more controversial and are generally not supported by genetic evidence, which indicates multiple migrations from Asia, beginning around 30,000 BP.