#5 of Our Top Ten Evolution Stories of 2014: Whale Hips, Another Icon of Darwinian Evolution, Takes a Hit
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In the case presented by advocates of Darwinian evolution, vestigial organs are a star in the firmament, frequently and gloatingly pointed to. Darwin himself cited them as such in The Origin of Species and The Descent of Man, referring to body parts like the human appendix that, he believed, no longer serve a function:
On the view of each organism with all its separate parts having been specially created, how utterly inexplicable is it that organs bearing the plain stamp of inutility... should so frequently occur.
Of course the appendix is a great example of an organ once thought to be without utility that now turns out to serve a vital role.
In the catalogue of purported vestigial parts, whale hips are "the marquee example," writes Stephanie Keep at the absurdly named "Science League of America" blog populated by our Darwin-lobbying friends at the National Center for Science Education. Unfortunately whale hips have now gone the way of appendix. A paper in the journal Evolution reports that rather than being a useless reminder of the evolutionary past, when whale ancestor Pakicetus strode the land on all fours, they in fact serve an unquestionably important purpose.
The pelvic bone supports the muscles that guide the penis. In male whales and other cetaceans, performance and thus successful sexual competition hinge on the size of the hips. The paper explains:
Male genitalia evolve rapidly, probably as a result of sexual selection. Whether this pattern extends to the internal infrastructure that influences genital movements remains unknown. Cetaceans (whales and dolphins) offer a unique opportunity to test this hypothesis: since evolving from land-dwelling ancestors, they lost external hind limbs and evolved a highly reduced pelvis which seems to serve no other function except to anchor muscles that maneuver the penis. Here we create a novel morphometric pipeline to analyze the size and shape evolution of pelvic bones from 130 individuals (29 species) in the context of inferred mating system. We present two main findings: 1) males from species with relatively intense sexual selection (inferred by relative testes size) have evolved relatively large penises and pelvic bones compared to their body size, and 2) pelvic bone shape diverges more quickly in species pairs that have diverged in inferred mating system. Neither pattern was observed in the anterior-most pair of vertebral ribs, which served as a negative control. This study provides evidence that sexual selection can affect internal anatomy that controls male genitalia. These important functions may explain why cetacean pelvic bones have not been lost through evolutionary time.
Under selection pressure from reality, Darwinists have already had to back away from Darwin's own understanding of what it means for a structure to be vestigial. Rather than serving no purpose, writes Jerry Coyne in Why Evolution Is True, now being vestigial can mean serving a different purpose than in one's distant ancestors. He defines "vestigial trait" this way:
A trait that is the evolutionary remnant of a feature once useful in an ancestral species but that is no longer useful in the same way. Vestigial traits can be either nonfunctional (the wings of the kiwi) or co-opted for new uses (the wings of the ostrich).
Stephanie Keep agrees:
[T]here's a problem when vestigial structures are defined as evolutionary remnants that have no function. As I discussed in a previous post, the correct way to describe a vestigial structure is to say that it no longer has its original function.
She is excited about Carl Zimmer's post on the subject, which elaborates:
While [whale hips] may not be essential for walking, they still matter a lot to whales. To see why, we have to go back to those hips of land mammals. They are important for walking on land, but they serve other purposes, too. Among other things, they anchor muscles that control the sex organs. If these muscles are anesthetized in men, for example, they have a hard time gaining an erection.
As whale hips stopped mattering to walking, they didn't stop mattering to having sex. In male whales, the pelvis controls the penis with an especially elaborate set of muscles. In some whale and dolphin species, these muscles make the penis downright prehensile.
You see the problem. Whale hips are "vestigial" yet still extremely important. Comments our colleague Michael Behe, "So doesn't that make everything a vestigial structure from a Darwinian viewpoint? And if so, of what use is the word?" Or as Jonathan Wells wrote here back in 2009 in reviewing Coyne's book ("The Myth of Vestigial Organs and Bad Design: Why Darwinism Is False"):
As [biologist Steven] Scadding had pointed out nearly thirty years ago, ... Darwin's argument rested on lack of function, not change of function. Furthermore, if vestigiality were redefined as Coyne proposes, it would include many features never before thought to be vestigial. For example, if the human arm evolved from the leg of a four-footed mammal (as Darwinists claim), then the human arm is vestigial. And if (as Coyne argues) the wings of flying birds evolved from feathered forelimbs of dinosaurs that used them for other purposes, then the wings of flying birds are vestigial. This is the opposite of what most people mean by "vestigial."
In this way, the concept of a vestigial trait is reduced to meaninglessness. In the most minimal definition, evolution denotes change over of time. No trait goes unchanged. Under the framework of Darwinian evolution, therefore, everything is vestigial. So nothing is.
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.