The Reason for Music
One of the books I'm currently reading is Why You Like It: The Science and Culture of Musical Taste by Nolan Glasser, chief architect of the Pandora Radio’s Music Genome Project. It's a 770 page doorstopper of a book that seems to encompass anything you'd ever want to know about music. My Kindle says I'm only 11 percent done but I've already found some tasty quotes, like this one from Steven Pinker about the utility of music who suspects that "music is auditory cheesecake, an exquisite confection crafted to tickle the sensitive spots of... our mental faculties."
I guess Pinker is saying that music has no usefulness. It's like a fattening, sugar-laden course after a nourishing meal. It's superfluous and it's only purpose is pleasure.
Martin Luther, on the other hand, believed that music was a gift from God and it's sole purpose was to glorify and worship Him.
My perspective, albeit unpolished and only partly informed, is that music is akin to humour: it's a coping / survival mechanism. It releases endorphins. It feels good and lifts our mood. I also agree with Charles Darwin that song is used for sexual selection and to attract mates, both amongst humans and other animals in nature. We can also use music for worship and creative expression.
All this, and with zero calories.