>> non-coding junk DNA which is under no selection pressure > "conserved" sections of DNA which don't change much over time I'm not a biologist. I imagine DNA

>> non-coding junk DNA which is under no selection pressure > "conserved" sections of DNA which don't change much over time I'm not a biologist. I imagine DNA that does nothing and is under no selection pressure should have a bunch of random mutation accumulated - the opposite of what you described.