Lighter said
> Part of the problem - if it is one - is that "evolution" usually implies an increasing complexity or sophistication over time.

Not at all! Biological evolution can go in that direction, or in the opposite direction to greater simplicity, but changes are often to new forms that are significantly different but much about the same in complexity.

Tunes can likewise evolve in various ways, as vividly illustrated by leeneia, 03 Jan 16 - 09:53 PM.