Traditions Evolve

Was listening to NPR and out popped this statement - "Traditions evolve". Is that a contradiction? How would you define Tradition? multigenerational, ancient, unalterable ....... Culture and custom are entwined with tradition. I can't help but hear the song by Tevye in Fiddler on the Roof - Traditions.

Evolution is the product of two opposing forces: processes that constantly introduce variation in traits, and processes that make particular variants become more common or rare. So will a tradition un-opposed become so rare it dies?
If so that means Traditions must evolve.
Change is a funny thing - full of ying and yang.