What is the real deal with the peppered moth?

@Relates

I really don’t see how anyone can mandate a Universal on this particular idea. Sometimes evolution rests on a single mutation… and that carries the day for a new sub-population.

Sometimes evolution rests on a mutation steadily working its way through an entire population…

Vagaries of environment and circumstances are constantly fluctuating. Trying to mandate either as a Constant seems like a fool’s errand.