[save_ferris]

Regardless of the genesis of how we discern music, specific modes have characteristics that are fairly universal.

For example, the aeolian mode is a much darker, sadder mode than the ionian mode. Why is that? I'm sure there's an intense debate there. I just study the theory, not the higher order biology/physics of why the music speaks to us the way it does. But the characteristics of modes and how they resolve are fairly established at this point.

[PaulDavisThe1st]

Sorry, but this probably wrong. Labels like "darker, sadder" are not inherent to the intervallic series of a particular mode. You could make some objective observation such as "there is more dissonace in the 3rd, 7th and 9th members of the harmonic series when comparing the notes that make up the major chord". But "darker, sadder" are emotional labels that are probably but not definitely socially constructed.

I had the experience once of seeing one of the greatest Indian vocalists of the 20th century live. The audience was almost entirely people of Indian ancestry, and clearly very experienced at listening to this sort of music - I was not. Indian music doesn't use harmonic relationships very much, but does have a much more clearly developed and articulated "theory of melody" in which specific intervals in an ascending or descending of a melody have particular meanings (within the context of a given raga (scale/mode)).

The audience would gasp out loud as he did certain ascents/descents. I kept looking at the person I went with (who had grown up listening to Indian classical music) and it was clear that to him the meaning of the note sequence was completely obvious. To me, there was no meaning at all.

As I mentioned, musicology research that I'm familiar with is still a bit ambiguous about this. It is possible that people from very different musical cultures might agree with your characterization of the intervals that make up aeolian as "darker, sadder", but I'm not aware of any definitive studies that show this clearly.