What theories exist for how the moai were moved around easter island?

The evidence on the ground revealed that roads were not part of some overall planned network. Rather they are the remnants of paths that moai transporters took as they walk the statues across the landscape,” they write.

While this helps explain how the statues were moved around the island, it doesn’t explain why. 

a chromatic scale uses the twelve tones of the octave, while a regular scale only uses eight, or seven different notes (as the first note is played twice)