Is your "impossible question" and challenge supposed to be akin to the problem of evolving a four-chambered heart from a three-chambered job? After all, you would argue that while converting the 3-chambered model to the 4, the whole thing would have be shut down, right?
Great idea for a new topic. Maybe you and barnes can get together on that.
If you have trouble with differentiating natural selection from the rest of evolution (mutation, speciation etc), look at Message 331 to see the specific role that selection plays in the evolutionary processes.
Failing that, start a new thread concerning what you don't understand.