Final answer:
The kelp highway theory suggests that humans migrated from northeastern Siberia to the Americas by boat, following a coastal route rich in marine resources. Evidence from South American archaeological sites supports this theory, but rising sea levels have submerged much of the potential evidence. Both coastal and interior migration theories are now considered likely and complementary explanations for the peopling of the Americas.
Step-by-step explanation:
The kelp highway theory posits that humans migrated from northeastern Siberia to the Americas by boat, utilizing a coastal route that capitalized on rich marine resources. This theory is supported by evidence such as archaeological sites in South America that predate those in North America, challenging the 'Clovis first' model. Additionally, the theory suggests that early migrants followed the continental coastline southward, relying on kelp, fish, and other marine life for subsistence, and may have reached as far south as Chile before moving inland.
The concept is further bolstered by the idea that Pacific sea travel along the coast would have been faster and more efficient than overland routes, allowing for a quicker spread throughout the Americas. The rich marine environment along the Pacific coast would have provided ample food resources for these maritime peoples. However, much of the evidence that could support this theory has been submerged due to rising sea levels since the Pleistocene epoch, making it challenging to find direct archaeological proof.
Nevertheless, most experts in the field acknowledge the plausibility of both the coastal and interior migration theories, with human migration to the Americas likely occurring both over land and by sea over an extended period.