In one more vain attempt to get people to understand evolution:
Imagine you have a bowl of candy and every day one a few pieces of candy from the bowl duplicate. Now if people ate candy out of this bowl and after a while what would happen? Well, interestingly it depends on the candy people prefer, if you really like skittles but you hate granola bars, then you'll eat the skittles and avoid the granola bar. As a consequence of this "predation" the skittles would be less likely to be that candy to duplicate as there would be fewer skittles in the bowl. Also the granola bars would be eaten far less often and as a consequence of nobody really liking them would become the dominate "population" in the candy bowl. If you ate the best candy, you'd end up with a population overwhelmingly made up of the least editable candy. If you "culled the herd" and ate only the worst candy in order to make sure the population of candy would all be of very good tasting candy, you'd be engaging in artificial selection. This is how we have giant cows and sheep with lots of fluffy wool. We have only allowed the best individuals to breed and the most wanted individuals to propagate and allowed the least desirable animals to die off without "duplicating" (reproduction).
Now, imagine if rather than a pure duplication you have a imperfect duplication only slightly though. You might end up with a slightly larger or smaller candy bar, you might end up with more nuts or fewer nuts, you might have a larger bag of skittles or smaller bag. You might have more green skittles than blue skittles. And these subtle mutations could occur every once in a while. Even if the most common one was a bit of a wonky candy bar or a messed up M&M. Then what would happen if you ate the ones you liked?
Not only would you end up with your least favorite candy you might end up with the smallest candy that looked ugly or reminded you puke or if you were inclined to eat many because they were small, you might end up with the candy getting large in order to sate your appetite with one sacrifice rather than enduring the death of several individuals. If you were to breed the candy for your liking. You could end up with bags filled with a single giant bright green skittle to the point that they don't even look much like skittles anymore. You could bread a second population of millions of tiny red skittles over the course of a long period of time. And while bags of tiny red skittles and giant green could seem like completely different candy, they would have descended from a common ancestor.
At what point are such things evolving? Make no mistake, this hypothetical candy bowl is evolving. Is it when you "naturally select" the candy? Is it when they duplicate? It's the entire process. In humans there are more subtle ways of changing and differences and rather than you eating candy we are faced with the prospect of the uncaring reality of organisms in the struggle for existence dying of disease, famine, and being devoured. But, like the candy, whatever is best suited towards survival is the most likely to survive and pass it's genes off to the next generation.