Where did music come from?

A recent thread at recording/music site GearSlutz indirectly seemed to ask the question of from just where did music come into human life and culture? I found myself writing this:

I think the answer, in part, lies with how our nervous systems evolved. The auditory system is in large part about spatial mapping... placing the organism within a given space, as well as tracking potential threats or prey within that space.

Watch an animal like a dog or cat and how they respond to their acoustic environment.

Introduce a new sonic element and they're on alert until they can determine whether it might represent a threat.

Reiteration of sounds -- and the rhythms of that reiteration -- are a key aspect that canny animals must be at least subconsciously aware of.

Rhythmic sounds tend to carry more weight because they typically signal that the source is animal, rather than environmental (the wind in the trees may have chaotic rhythms, but it's nothing like the threatening beat of a large animal coming toward one).

But pitch is almost equally important... what's more threatening, the low frequency roar of a lion, or the twittering of a meadow lark? (OK, cheap example, but you get the drift. )

As human circumstances improved and we had to be less attuned to sound for survival's sake, we were left with a big, under-used center of the brain... like a traveler doing crosswords in a terminal, early man probably tickled the auditory system in the brain by intentionally making various noises, particularly rhythmic noises.