Samantha - In our local Natural History Museum, there's a cast of Lucy, our 3 ft tall 3 million year old Australopithecine ancestor. I have a theory (and why not?) that music in our evolutionary lineage must have preceded language, I always see her running through that ancient forest, singing musical calls to her mates.
PS - Outside of the Grateful Dead, too, the musical piece that drives me nuts is Prokofiev's Classical Symphony.
Also ... Do you know this amazing bluegrass album that Jerry Garcia is on?