Mark Changizi suggests one theory:
Human movement has been conjectured to underlie music as far back as the Greeks. As a hypothesis this has the advantage that we have auditory systems capable of making sense of the sounds of people moving in our midst – an angry stomper approaching, a delicate lilter passing, and so on. Some of these movements trigger positive emotions – they conjure up images of pleasant activities – while others might be automatically associated with fear or anxiety.
This article available online at:
http://www.theatlantic.com/daily-dish/archive/2009/09/why-does-music-make-us-feel/196330/
