This is a special post for quick takes by TurnTrout. Only they can create top-level comments. Comments here also appear on the Quick Takes page and All Posts page.
"Why do worms regenerate without higher cancer incidence? Hm, perhaps because they were selected to do that!"
"Evolution did it" explains why a trait was brought into existence, but not how the trait is implemented. You should still feel confused about the above question, even after saying "Evolution did it!".
I thought I learned not to make this mistake a few months ago, but I made it again today in a discussion with Andrew Critch. Evolution did it is not a mechanistic explanation.