[mkl]

You have it backwards. Polynesians travelled to South America and back, acquiring sweet potatoes there, possibly some human DNA, and leaving chickens (there is good evidence for each of these, but it's not undeniable). There is a huge amount of evidence of Polynesians travelling long distances by sea, and, as far as I can see, essentially no evidence for South Americans doing this. The fact that it was theoretically possible does not mean it happened.

[drumdance]

Last year at the local planetarium I saw a great presentation about how the Polynesians navigated using the stars. It was a tradition that was almost lost, but they found someone in the 70s whose grandfather had taught him how, and now they have a school in Hawaii that teaches it.

http://pvs.kcc.hawaii.edu/index/founder_and_teachers/nainoa_...

Interestingly, part of their motivation in reviving it was that they were offended by Heyerdahl's hypothesis, which in their view basically said "Polynesians were dumb enough to get on a raft and just let it drift." More recently DNA analysis has shown that Polynesians came from Asia, not South America.

[bebop]

FYI his name was Mau Piailug: https://en.wikipedia.org/wiki/Mau_Piailug