I'm only asking from my intro to anthropology experience.
In the 1960's Thor Heyerdahl reconstructed a raft that would have been used by ancient people to travel by wind and travel west across the pacific ocean. He did it successfully with no modern help. This was apparently so controversial because it sounded crazy, but also this theory and Monte Verde challenged the commonly held Northwest passage across Alaska theory.
We only learned about the theory, not how receptive the anthropological community was to this idea. How is research at Monte Verde going, and do people generally believe that Oceania was at least partially populated by people from South America?
It's possible, but that's probably not what happened. The indigenous people of the Polynesian islands making up most of Oceania all share a common language family which can be traced back to Formosan culture in Taiwan. More likely, Polynesians visited South America rather than the other way around (as evident for the Polynesians of Easter Island).
The lack of navigational expertise for South Americans would had been a huge hurdle for them to reach such far off islands. Mr. Heyerdahl might had sailed in an Incan raft, but he had modern navigation tools (sextant and charts), and most importantly, prior knowledge of the existence of these islands to aid in his expedition. It's also important to note his theories were created before modern genetics allowed for a clearer picture of human migration.