I always had this strange gut feeling that pure drawinism wasn't going to be an acceptable explanation for our world. I agree that in theory it could work, but I was never able to believe that the results we observe in nature could be justified from a numeric point of view only by natural selection. With this I mean that in my opinion natural selection simply couldn't have enough strength to make the human body (just for example) such an impressive machine.
Recently when my mother had a thrombosis problem I discovered things about how our blood works that I didn't know. Just the explanation of how our body reacts to an injury trying to prevent the losing of too much blood is impressive. Just that little bit is incredibly sophisticated and requires a very precise equilibrium... too much of a value and your blood is going to coagulate when there's no injury, and you die; a value too low and your body will not be able to stop losing blood from a little cut and you also die. Thinking that such a perfection comes by mere natural section doesn't seem to me reasonable.
Yesterday I stumbled in a page that explained that exactly the machinery required to coagulate our blood when needed is a part that is hardly justifiable by natural selection. It's a chain reaction of activations of proteins where no mistake and no misregulation is allowed, and so it's hard to justify how such a system could have been evolving one step after another because in that system you can't change just one variable, you have to change several at the same time to keep the balance. In other words the idea that the system has been reached by casual mutations that produced a sequence of organisms every one better than the previous one simply doesn't work; the intermediate ones would have been not better, and so they've no reason to survive. I don't know if I like the position of Intelligent Design (even if admittedly would make things a lot easier to explain; especially if you don't make the big jump of assuming the existence of a god but just that of someone - necessarily non-human, but not necessarily super-human - that is directing or has been directing the evolution) but I'm happy to see that at least to someone else the pure theory of evolution doesn't seem plausible.
Another doubt I always had since I was a kid is about glacial periods, I wonder if indeed even that area is seriously under discussion.