The trouble with evolution as a theory is that it doesn't quite fit the facts, at least as I was taught them. (I'm not sure what new findings have emerged on the subject in the last decade or two.) We can look at fossil evidence, date it, and determine that certain species existed millions of years ago that are similar, but not the same, as modern species. We can look at evidence today and see how certain differing species share various similarities. From this, we logically postulate that the species must be related; they have a common ancestor. A now-extinct ancient species evolved into a modern-day species. This is a perfectly reasonable hypothesis
Stephen J. Gould used the panda's thumb as a fine example of evolution in action. The chain, as I recall, went something like this: the panda started with a hand like ours, which evolved from four fingers and a thumb into five fingers at the front of the paw. Later in the game, the panda needed to use its forepaws to strip bamboo, a task better suited to a paw with a thumb. But the panda had already lost its thumb. The modern panda now has a 'sort of' thumb. It's actually one of the bones from the wrist, pushed up and forward to make shift for the specialized task of bamboo-stripping Gould offered that intelligent design might well produce the elegant perfection of a bird's wing, but only 'whatever works' evolution would come up with using a wrist bone for a thumb.
And this is all good.
My trouble with evolution has always been following the jump between one distinct species and the next. Scientifically, species are not defined by their similarities in appearance or function, but by biological compatability. If two animals can interbreed and produce fertile offspring, then they are of the same species. Thus, a Chihuahua and a St. Bernard are members of the same species, while a fox and a beagle are of separate ones. As are horses and donkeys, which can mate, but whose offspring (mules and hinnies) are sterile.
Genetic studies, and the very existence of umpteen varieties of canines, more or less prove the whole mutation theory -- that is, that the offspring of two animals can, on rare occasion, exhibit qualities not present in its forebears, or at the very least, not at all observable in any of its distant ancestors.
Evolutionary theory goes one of two ways from here. Either we get 'gradual change' whereby, say, the offspring of two given lynxes is somewhat cat-like, and then that cat-like lynx has offspring which are even more like housecats, and so on, until finally we get housecats which are not able to breed with lynxes. (Example purely facetious; I have no idea what housecats purportedly evolved from, but I doubt it's lynxes.) Or there's the 'evolutionary leap' version, which says that one day, a pair of lynxes produce a housecat.
The difficulty I have with the 'gradual' version is that, well, why are Great Danes and toy poodles still genetically compatible, even after thousands of generations of being bred apart, and for totally different qualities? If we are to postulate that everything evolved from protofish species, what use was the half-a-wing non-flying version of a bird?
And the 'evolutionary leap' has its own problems. If one day a bird hatches from a raptor egg, where does the newly mutated bird find a mate? What are the odds of two new creatures mutating in exactly the same way so that they can breed with each other but not with their forebear species?
As I recall, fossil evidence isn't just missing a link between man and apes, but the links between most old and new species, if you're going by the 'gradual change' version of the theory.
The theory of evolution isn't a proven fact. Most scientists recognize this, and their response is: 'So, you got a better idea?'
'Intelligent design' is not, in my humble opinion, a 'better idea.' That doesn't mean it's wrong. Lemme give an example (I think this was from Gould, too):
Say you are sitting in a room, and suddenly, the light goes out. Now, you can postulate many different reasons for why the light went out.
1) The light bulb burned out
2) You forgot to pay your power bill
3) Your state has adopted California-style utility deregulation and you are now reaping the benefits
4) The gods want you to sit in the dark.
Based on the information I have given about the situation, all of these possibilities are equally likely. However, assuming that you don't want to sit in a dark room, you should always start with (1) as your working hypothesis, because it's the theory which is most easily tested and leads to the quickest resolution.
It's entirely possible that (4) is right, and there's no way to prove that it is, or isn't. That's what makes is a bad working hypothesis: you can't do anything with it.
That's my problem with "intelligent design" as a working hypothesis--I can't work with it. Evolution, as an explanation for how the human race came into being, may well be entirely wrong. But it's led to many discoveries in numerous different scientific fields. Even flawed, it's been a useful working theory.
But, given that there are clear flaws in evolution, I am surprised by the vehemence with which some people assert that it is fact. That suggests a lack of serious examination, an unwillingness to question and to explore alternatives. Saying 'Evolution is just true' isn't any more useful than saying 'Intelligent design is just true.' Neither one leads to new tests, new discoveries, new insights.
Anyway, having written all of this off the top of my head (which is a nice way of putting it than 'pulled it out of my ' -- er, never mind), does anyone know if the troubles I've mentioned have been addressed? Have vestigial-winged proto-bird fossils been unearthed? Is there a 'third path' on evolution that I'm not familiar with? Is there a provable explanation for 'simultaneous mutations into a new species' or some such?