* He notes that octaves are common across cultures (per Levitin, "This is Your Brain On Music")
* He asserts that 12 tones represent a practical limit to harmony; more than 12 tones is more complex than the brain can handle in its "note-expectation engine".
* He thinks other cultures could be working within his theory, but simply not taking advantage of _all_ of the universal harmonic features that Western music offers. He cites pentatonic scales as an example.
* He is baffled by the Nasca Indians of Peru, who apparently form their pitches by linear steps in frequency rather than logarithmic (I won't even attempt to use the word "harmony" in this sense), but he asserts that 1) their tuning system was probably derived because it was mechanically easier to produce a set of pipes to that tuning system, 2) they're a weird case because they were isolated.
* To finish that reasoning off, he suggests there's a "musical sophistication" of a culture which develops from linear scales (easy to carve) on the simple end to equal temperament on the sophisticated side (because arbitrary key changes without wolf intervals is the ne plus ultra, right?).
So, yeah: I'd say there's some serious cultural narcissism going on. It would be OK if he confined his analysis to Western harmony and simply tried to explain what was going on there, but by trying to derive universal musical principles from barbershop quartets, his project was pretty much doomed from the get-go. :-)
Nature is the aspects of harmony that independent societies have all agreed upon, likely due to an unknown biological reason harmony sounds pleasant. Nurture is the connotations society and culture put on top of that.
The author is only attempting to explain the nature part of things.
You wouldn't fault the theory of gravity for not explaining cell biology, so let's not fault this guy for ignoring culture.
the same kind of weird cultural narcissism / racism / whatever it is happens in language, with "correct" usage of words. its the same damn thing.
and can i just add, for all the overly left brained harmonic analysers out there- it would be nice to see someone address the fact that harmony, even in the restricted western classical sense, i guess "diatonic", depends greatly on timbre and range as well. of course i didnt read this paper, and instead ranted somewhat incoherently about topics which might not even apply to the paper, but hey, i had a good time!