This is a great question and there has indeed been research into this that has yielded some theories.
Theory 1: (audible patterns)
There is a theory that peoples that lived in grassland savannas tend to have more intricate musical patterns than peoples that lived in other terrains. The thought being that grassland and lowland savannas by nature tend to allow sound to travel further and more accurately. This is thought relevant due to hunter gatherers leaving the homesite further and further away and over time using chants, percussions and "music" as a communicative network with the homesite.. Over time, this disposition toward chants, pervussions and music proves beneficial and is made more complex to communicate more complicated messages...thus over time providing survival value that can be refined and passed fown through darwinian and mendelian mechanisms.