Never mind evolution - we can definitely prove de-evolution exists because we can observe it in our lifetimes. The latest example is a band once known as "Chicago Transit Authority".
They didn't take long to start going downhill. Guitarist Terry Kath killed himself with a pistol that wasn't loaded 26 years ago tomorrow. The ballads and top 40 crept in. Yeah, they must have made tons of money for somebody. But IMO inside they were probably saying don't listen to us - we don't want you to hear us this way.
Now their back catalog is distributed by Rhino Records, and their "greatest love songs" are for sale on TV. Can they go any lower?