Quote:If this bone was not essential to the animal's functioning, then again evolutionary principle has been violated because it should not have evolved.
I could surgically remove your cecum, and you would survive -- at least, you'd survive without the cecum; you might not survive my surgical technique.
I could remove a horse's cecum and it'd be dead before you could say "hi-ho silver."
It's not a question of whether something is essential, but rather a question of an inherited tool kit and relative advantage. Perhaps the bone (pure speculation here, just for sake of example) was important to the proto-fishes for prehension, combat, digging, receiving radio signals from extraterrestrials, or whatever. The family was successful, the family diversified, the family retained certain familial traits that may or may not have been of any importance any more. (Just as the color of one's skin might have meant the difference between life and death at some point in the past, whereas now it may -- in some utopian land -- have no bearing on survival whatsoever.) However, unless there is a selective pressure
against the retention of this structure, it's unlikely to vanish too rapidly. Sort of like our little (outside, fifth) toes: they serve virtually no appreciable function, but we've still got them. The fish's genes (in my hypothetical world; I know diddly squat about this species in particular and little more about genetics in general, though probably quite a bit more than the average bear) still program for that bone to form. Whatever genes influence the development of this bone change (or not) as chance allows until, my happy circumstance, it ends up somewhere else where it performs a useful function -- in this case, vibrating sympathetically with outside noise. Now, perhaps, it confers an advantage to the individuals with the particular suite of alleles that favors it's development.
As to the eye thing -- I resorted to looking at answersingenesis for their review of Dawkins' book "Climbing Mt. Improbable" to purview the dogmatic objections vis-a-vis evolution of the eye.
http://www.answersingenesis.org/tj/v12/i1/improbable.asp
I find nothing about the eye having evolved mutliple different times (perhaps a different book?). I do find an irreducible complexity argument. Much of the critique is centered around the necessity of complex decision-making machinery being necessary to interpret optical information -- that is, there's no point in detecting light if you don't have a brain. There are many single-celled Eukaryotes and Prokaryotes today that have systems for the detection of light and that put this information to very good advantage. There are bacteria that respond to light by moving toward it or away from it, and the only machinery necessary for this to occur is an "eyespot," a flagellum or three, and a simple chemical cascade that results in greater or lesser flagellar activity in response to increasing or decreasing intensity of light.
There's also the usual "biochemistry itself is too complicated to have evolved," but that issue is hardly unique to the topic at hand.
Oh, gawd, you mean we are all Canucks?
