Vestigial organs are relics, reduced in function or even completely losing a function. Finding a novel function, or an expanded secondary function, does not make such organs non-vestigial.
The appendix in humans, for instance, is a vestigial organ, despite all the insistence by creationists and less-informed scientists that finding expanded local elements of the immune system means it isn’t. An organ is vestigial if it is reduced in size or utility compared to homologous organs in other animals, and another piece of evidence is if it exhibits a wide range of variation that suggests that those differences have no selective component. That you can artificially reduce the size of an appendix by literally cutting it out, with no effect on the individual (other than that they survive a potentially acute and dangerous inflammation) tells us that these are vestigial.
I went through this whole ridiculous argument years ago, when the press seized upon an explanation of immune function in the appendix to suggest that a key indicator of evolution was false. It was total nonsense, that only refuted a straw version of creationism. I even cited Darwin himself to demonstrate the ignorance of the concept by the modern press.
An organ, serving for two purposes, may become rudimentary or utterly aborted for one, even the more important purpose, and remain perfectly efficient for the other. Thus in plants, the office of the pistil is to allow the pollen-tubes to reach the ovules within the ovarium. The pistil consists of a stigma supported on a style; but in some Compositae, the male florets, which of course cannot be fecundated, have a rudimentary pistil, for it is not crowned with a stigma; but the style remains well developed and is clothed in the usual manner with hairs, which serve to brush the pollen out of the surrounding and conjoined anthers. Again, an organ may become rudimentary for its proper purpose, and be used for a distinct one: in certain fishes the swimbladder seems to be rudimentary for its proper function of giving buoyancy, but has become converted into a nascent breathing organ or lung. Many similar instances could be given.
I’m dragging out Darwin because it’s happening again. An analysis of whale pelvic bones supposedly refutes the notion that they are vestigial, because they play a role in sex.
Both whales and dolphins have pelvic (hip) bones, evolutionary remnants from when their ancestors walked on land more than 40 million years ago. Common wisdom has long held that those bones are simply vestigial, slowly withering away like tailbones on humans.
New research from USC and the Natural History Museum of Los Angeles County (NHM) flies directly in the face of that assumption, finding that not only do those pelvic bones serve a purpose — but their size and possibly shape are influenced by the forces of sexual selection.
"Everyone’s always assumed that if you gave whales and dolphins a few more million years of evolution, the pelvic bones would disappear. But it appears that’s not the case," said Matthew Dean, assistant professor at the USC Dornsife College of Letters, Arts and Sciences, and co-corresponding author of a paper on the research that was published online by Evolution on Sept. 3.
Of course the creationists are thrilled to pieces. The press loves the spin of evidence that ‘refutes’ evolution, but the creationists love it even more. After telling us that scientists keep changing the meaning of vestigial, they crow over this rebuke from one of the authors of the study:
This is not just our observation. The scientists who revealed the usefulness of whale hips are rethinking what it means to be vestigial. Or so it sounds from the remarks of biologist Matthew Dean at USC, a co-author of the paper in Evolution, commenting in Science Daily:
"Our research really changes the way we think about the evolution of whale pelvic bones in particular, but more generally about structures we call ‘vestigial.’ As a parallel, we are now learning that our appendix is actually quite important in several immune processes, not a functionally useless structure," Dean said.
Anyone who thinks whale hips are functionless, just like your appendix, should try telling that to a lonely gentleman whale. The career of this evolutionary icon isn’t over yet, I’m sure, but its importance in the evolutionary pantheon is due for a serious downgrade.
I’ve read the paper. It’s about a hypothesis that sexual selection may be maintaining the pelvic bones; it discusses purely evolutionary hypotheses at length, and is not a paper to support intelligent design. Yet here one of the authors is parroting common misconceptions about vestigial organs, and that is infuriating: if you’re going to write papers about a subject, you should know your background adequately. No, finding a retained secondary function for an organ does not mean you have to rethink vestigial organs. See Darwin again.
An organ, serving for two purposes, may become rudimentary or utterly aborted for one, even the more important purpose, and remain perfectly efficient for the other.
It turns out that I also have those same muscles, attached to my pelvis, and I can actually wiggle my penis at will (I hope I don’t have to demonstrate this; any human male will do as a demo, just ask, or try it yourself.) I also use muscles attached to my pelvis to…walk. Whales have reduced, vestigial pelvic bones that have lost the functions needed for walking, but have retained a function for wiggling their penises. This is not a surprise; it is not a revelation that changes our understanding of evolution; I would not get a prize if I showed at the yearly Evolution meeting, dropped trou, and demonstrated my skills with a tassle.
Fools of the Discovery Institute to the contrary, whale pelves are still excellent examples of vestigial organs, and haven’t been ‘downgraded’ at all. And if the IDiots want to argue that we’ve been jiggering the definition to match circumstances, I’ll just point them to that Darwin quote again. Can’t get much more basic and original than that.
An organ, serving for two purposes, may become rudimentary or utterly aborted for one, even the more important purpose, and remain perfectly efficient for the other.
I will say that I wish investigators in evolutionary biology had a better grounding in elementary evolutionary theory, so they would stop inventing these imaginary conflicts to puff up their work.
Let me just add, the paper is fine — it covers the specific topic of its title, Sexual selection targets cetacean pelvic bones, perfectly well. It’s these off-the-cuff remarks to the press that reflect an embarrassing ignorance.
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