"No such thing as a vestigial organ, every single organ ever said to be vestigial has later been discovered to have a function. Some of them had very important functions. Organs that do not have a known function at this time, such as the laryngeal nerve, will probably be later discovered to have a function. By laryngeal nerve, I mean the excess wrapping around other organs rather than going straight to it's destination."
Interesting that this was posted right after Aelyn posted a clear explanation of what vestigial organs are. Withour_Excuse didn't bother to read, just posted, I guess.
Vestigial organs certainly do exist - in fact, most evolutionary change depends upon them. Any character state. organ or organ system that evolves renders its previous states vestigial of any change in function takes place. The feathers in birds, now clearly related to locomotion (flying) are simply vestigial thermal blankets which became co-opted by evolution for gliding and then flying. If you are actually interested in learning more about this from the perspective I've introduced above, read "The Spandrels of San Marco and the Panglossian Paradigm" by Steven J. Gould.
Vestigial organs are often reduced from their pre-cursors, as Aelyn noted, and that is certainly the case in most of the classic examples - whale hindlimbs and human tails, for example. Their functions are sometimes less complex than the earlier function - but not always. Besides, the complexity of a function is a bit difficult to measure in any really stringent way.
I will point out that my reply partly inspired itself from the Wikipedia article on vestigiality, that makes a clear distinction between vestigiality and exaption. Basically while both vestigial and exapted features have lost their original function (or, if you don't accept evolution, the function their homologs have in other groups), vestigial features have either no function or a function that is minor compared to the original, whereas exapted features have a different function that is just as important as the original one. I illustrated this with a contrast between whale flippers and whale pelvic bones.
Just saying that while I agree with the main thrust of your post, I'd definitely count feathers as an exaption rather than a vestigial feature. Modern feathers in birds not only play a role in insulation, they have even more important roles, namely flight. (on the other hand one can
make a parallel argument on the almost-flight feathers of flightless birds)
I guess one could argue that to distinguish between vestigiality and exaption is meaningless because in the context of the theory of evolution we expect to see a continuum between vestigial and exapted features (depending on how important we deem a novel function to be). But the concept of "vestigial" features is still relevant in that it makes a statement on the direction
we've observed in their evolution*, and that we anticipate observing in the future. In an exapted organ we expect to see modifications related to their new function, and stability in the future (insofar as the optimal structure for said function is more or less attained; I'd say that's the case for feathers and whale flippers for example); we also expect to see change
that can't be summed up as "reduction". In a vestigial organ we expect to see simple reduction, with further reductions in the future (even in organs that have function; for example even if we assume the pelvic bones' function anchoring muscles in whales is vital, their variety makes it clear they have quite some leeway to reduce further before functionality becomes an issue.)
*One difficult but important thing to remember is of course that evolution isn't teleological, and doesn't have a "direction" in the sense that it has foresight. But that doesn't mean that evolutionary change is arbitrary; it depends on the environment and the selective pressure it implies, and if said selective pressure is the same for a given group for a long time we will
observe evolution going in one direction. This is even more evident when we ignore the side branches where the selective pressures changed and evolution went a different way.
Hi Rich and welcome to the forum! Could you please use the "Quote" button at the bottom right hand corner of the post so we can see who you are quoting. I never made the claim that all cetaceans have the same reproductive systems. So I don't see what your point is. Whales would probably need something as strong as dedicated bones because of their size. That other cetaceans lack "pelvic bones" would seem to be an argument against evolution, not for it. And we know that these are "remnants" of these bones because..??? No, that is not how long we have "known" that they are vestigial. We don't know what we can't prove.
Um, I didn't mention that some cetaceans have no pelvic bones because I couldn't actually find any evidence for that claim (as I said I found evidence neither for or against, I'd love to know you people's sources), but you said
that whales couldn't reproduce without them. The existence of cetaceans that don't have them in the first place but reproduce fine would be a straightforward refutation of that claim. As for them being a piece of evidence against evolution, I don't see it, care to explain ?
And we know that these are "remnants" of these bones because..???
Because anatomists who spend their lives looking at hips, femurs and tibias recognize them as such ?...
No, that is not how long we have "known" that they are vestigial. We don't know what we can't prove.
There is no such thing as absolute proof in science. There is evidence, and more or less of it. There is lots of evidence that whale pelvic bones, and the bones associated with them, are in fact homologous to other mammalian pelvic and limb bones.