An article in the economist describes three hypothesis of why something like music has come to existence.
They discuss three possible reasons :
- it helps for partner selection, just like for example the peacock tail does
- it has a social function to bind groups of people together which gives them an advantage over less binded groups
- it has been accidentially invented, and offers no advantage
It is clear that the third is contradictory to the former two AND it is not very likely that something as important and ubiquitous as music could have come into existence without any advantage for the performers.