I wasn't expecting this, but ok.
In science, everything backs each other up. DNA confirms the theory of evolution. Species migration? It comfirms plate tectonics in geology. Relative dating by guide fossils? Is confirmed by radiometric dating. (Yes, that is right, no one even needs radiometric dating to prove evolution, but it's nice to have.)
Let me make it simple. There is anatomy. Homologues structures denote the family tie. For example, we have the shark. The shark is unique in many ways because of the low and flexible mouth, the spinal cord that extends upwise at the back, the fins, the absence of the swimming blatter, the absence of real bone, the skin teeth, etc etc. So we can all see something is a shark right? A pelagic shark looks way different from a benthic shark, yet it is a shark. Before people knew much about the details of evolution, they still knew the shark and the ray are related, based on very specific anatomy. Look at the structure of a ray very closely. It isn't much else than a flattened shark. These are related, and the DNA confirms it. It isn't circulair, it both says the same thing. It isn't 1 point of evidence, it is in fact 2.
Now we take the whale shark and the whale. These are very similar in appearance and in lifestyle, they are even filter feeders. Are they the same? No, in fact the whale shark is STILL a fish and the whale is an aquatic mammal. They couldn't be much more apart. I know there are better examples than this, just giving you an idea.
To the second point:
No one is asking you to accept a theory that drastically changes your life. Why would it? Religious grounds? There is nothing wrong with theistic evolution. And you are free to dissmiss what i say. I didn't bring it up. If you ask me, I will tell you what I know.
Now, the thief with a stolen car in his garage is akin to the fossil record. The species must have gotten there somehow. However, species become extinct and they are also unique to the layer in which they are found. If you take one act of creation and take it from there without any way of backup, life would be near extinct or extinct now. Fact is extinction waves did happen. I see you didn't understand my last point, so let me try that again.
Guy is doing research in the ground. He finds all kinds of life in some strata, where this life is absolutely absent in the next. (For example, take the Dinosaurs.) That is odd, he thinks. Every now and then we see massive extinction waves. Must have been an act of God. So every now and then God wipes out some creatures and puts new ones in place, or there would no longer be life. No matter how you put it, this is staggered creation and not one act of creation.
These ideas were later refined. Extinction waves happened, but not in the way Cuvier described it. There is a model of at least 11 steps that takes us from the land animal to the whale. 11 divine modifications in that period? Looks like a lot. And no, it is not circular reasoning. The whale is unique and especially the inner ear, which we do not find in other mammals.
We can see how difficult it is to defend non evolutionary theories. If God did zap the whale 11 times to make it look like something else, it is still evolution. The question is not if evolution happened, but how.
To that other point, which I had neglected: (I blame it on lack of coffee)
It is true observed evolution must be extremly limited. We may be able to speed up the process, but you can't expect much in a few decades. It is possible to isolate 2 groups of the same species in a lab. If they reproduce fast, like fruit flies or moths, you can isolate them for several generations. It has been demonstrated if we do this, most likely nothing will happen. Now repeat the experiment, but put one group in light, the other in darkness. After the same period, the two groups will most likely refuse to interbreed. Can't always be sure, but it has worked in labs. That is speciation. Adaptation is something else. If you want to hammer the point home no one turned a fish into a reptite, noted. That is all work in progress. Right now we have the DNA and the transitional fossils.
The point is, evolution much relies on environment and competition. The best species are all occupying the best spots right now. After an extinction wave we are much more likely to see evolution, since the ecological niches open up. Of course that is all a bit of a moot point. Humans are a tiny dot on the geological time line as of now.
I hope that helps
Day
