Here's an excellent case: applying evolutionary principles to cancer improves diagnosis. You are a collection of (mostly) dividing cells, a population moving forward in time, and understanding that explains a great deal about how changes, like cancer, can occur. Okay, I wasn't paying close enough attention, I guess. Who was saying doctors didn't need to know evolution? yeah, but that's just micro evolution. Besides, it's also defying YHWH's will, since if He didn't want you to die from...
Who says doctors don't need to know evolution?
Pharyngula
