Final answer:
The discovery of 15,000-year-old rafts and canoes would support the coastal migration theory over the Bering Land Bridge theory, suggesting an earlier and more diverse pattern of human migration into the Americas, including sea travel along the Pacific coast.
Step-by-step explanation:
If evidence of 15,000-year-old rafts and canoes was found along the Pacific coast, it would likely challenge current beliefs about early Amerindian migrations. This discovery would provide support for the coastal migration theory, suggesting that people arrived in the Americas by following the coasts across Asia and the Bering Land Bridge, eventually reaching South America. Artifacts such as Monte Verde in Chile and Taima-Taima in western Venezuela contradict the Clovis first theory, as they are dated earlier than the Clovis sites and suggest that earlier human presence in South America could be due to such coastal migrations. The discovery of these ancient watercrafts would further strengthen the hypothesis that early human populations in the Americas might have used sea travel to migrate, a scenario which also aligns with linguistic evidence showing differences between coastal and interior indigenous languages.