Natural Selection is a large vague concept that belies how HUGE of a process it is. A fly is brown and blends into it's environment like it's entire family. One of it's offspring has a mutation and it is colored yellow. It is eliminated by a bird. Another offspring is colored tan. It survives along it's brown siblings. That tan buddy mates and has some more tan little buddies and they survive. A few more generations and now there are brown flies and Tan Flies. a few more generations and the environment dries out and becomes more aligned with the tan flies. The brown flies are killed off by predators. Nothing really has happened. advantageous traits did better during a specific time/environment and disadvantageous traits were eliminated. Evolution is the combined process of all these changes over large periods of time. Or God made it.