I'm reading a book at the moment called "The Singing Neanderthals".
The author's argument is that music is a holistic mode of communication, as opposed to speech, which is synthetic. Holistic communication is a form of signalling, where the messages conveys an overall piece of information, but are not very flexible as far as variations on meaning are concerned.
Synthetic communication allows for the composition of totally original messages.
To cut a long story short, he suggests that singing is a precursor of language. Since written language comes long after spoken language in history, the music of pre-sapiens homimids must have been passed on by oral tradition- for up to 20000 years in the case of the Neanderthals, they were clearly the first folk singers.
Cheers
Dave