It's not uncommon for supportable facts about the one thing or the other to be challenged by the vigorous interposition of the immediate announcement of some unsupportable assertion about the matter springing from the resolute lips of those compelled for their own good and sufficient reasons to resist the fundamental imposition such facts represent on their understandably favored view of everything.
As a matter of practical humanity it's personally difficult to resist the inclination to adhere to the favored view, for all the good it generally does, with whatever amount of tenacity seems appropriate.
Those bothered most by assertions of supportable facts sense a threatening move on the part of those facts not only to shift the position of their favored view with those facts, an accommodation most people might begrudge is due, but to dislodge it entirely from what was previously understood to be its favored precinct, like an abalone in the shallows of the sea popped off its rock by the actively advanced pry bar.
Such is the case with people presently driven here in the United States to create their creation science or spawn their intelligent design in heartfelt reaction to the dull threatening realities of evolution by natural selection, hoping to see their beliefs substituted for the evidence at hand, particularly when it comes to the approved store of knowledges of the nation being parceled out to our nominally educable youth in public schools across the nation these days.
Supportable facts are always the rub in foundational arguments such as the ongoing foundational argument for evolution these days between people who know something about the supportable facts like P.Z. Myers, the biologists and geneticists and geologists and paleontologists and their kind, versus proud groups of god-deluded citizens who insist there must be somewhere in this fact-based narrative of life on earth to shoehorn in the unsupportable assertions of their own understanding of its creation as variously written in their variously holy books, none of which narratives of creation can be true unless all the others are false, creating a truly dramatic and admittedly absorbing Mexican standoff of unsupportable foundational assertions against which the supportable facts of people who know what they're talking about can easily enough go ignored at times unless they're promoted as vigorously as they are by folks like P.Z. Myers.
People who know what they're talking about have been actively arguing evolution's merits on the internet, pushing back against a lot of compulsively spread hooey about the matter, for a long time. The Usenet forum talkorigins.org. began in 1986, and it's far from finished going on about evolution. Undeniably, if anyone is to say anything useful about evolution at all in light of all the argument about it collected there at talk.origins over the years, they should at least show that they're familiar with the collected shape of that argument, with what's been gone over again and again at talk.origins down the years, the supportable facts of the matter, unless of course understandably enough they merely wish to say whatever unsupportable something or other rushes to their lips in the heat of what they recognize as a fundamental assault on their favored view.
P.Z. Myers himself, aside from being a Professor … of Science!, is among those who's spent a good amount of time on the internet distinguishing the supportable facts from the unsupportable assertions of evolution by natural selection in the well-established argument laid out not only at talk.origins over the years, but, with the advent of the world wide web and blogging software and all, such sites as Panda's Thumb, where I suppose I first encountered P.Z. Myers's writing.
Panda's Thumb was and is a weblog published by a group of academics who have a command of the supportable facts of evolution by natural selection and a taste for laying into the claimed "science" of the proponents of Intelligent Design, which represents the latest expression of the continuing outcry of people really fundamentally challenged by the crimp all this evidence of natural selection puts in their favored god-deluded view. I suppose, without ever having bothered to find out, that the blog's name is a reference to Stephen Jay Gould's popular book of the same name.
Myers is a biologist, a professor of the stuff at the Morris campus of the University of Minnesota, giving him a vested interest in seeing that god-deluded claims don't interfere with the functioning of his profession. His blog Pharyngula is well-visited.
Often enough the comments attached to the regularly updated writing of Professor Myers posted there at Pharyngula are awash in outbursts of text from those who feel most keenly the contradiction to their favored view embodied in evolution by natural selection, outbursts dealt with summarily by P.Z. Myers and the band of others who've joined there in an ongoing correspondence, inhabiting a public space where the inevitable ongoing intrusion of unsupportable assertions into the argument for evolution by natural selection can be given the focused back of the public hand by those who know their supportable facts and all.
I admit I'm moderately uninformed on these matters myself.
Once in awhile P.Z. Myers puts down his cudgel and resorts to writing down the supportable facts of his craft, the science of biology. Some time ago he wrote what must have seemed to him a brief overview of the role of the hox genes in the structural development of embryos, no doubt gathered from all the notes he's piled up over the years representing his developing understanding of the subject, such as it may be. I'm not sure that Hox genes are the focus of P.Z. Myers's interest in biology. They may be just something he knows about as a matter of course, being a professor of the stuff.
It's just as well that he writes lucidly on the subject, because explaining the intricate workings of Hox genes involves marshaling a lot of complicated general knowledge, of DNA and chromosomes and embryos and such, and then adding to those complications the specific complication of how Hox genes themselves physically fit into that general picture, with all the basic good they do regulating the embryonic development of the physical framework of the beast that owns them. Hox genes ensure that the front of the beast and all its associated bits goes here, the mid goes here, and the back end with all its trailing matter goes back there behind, all according to the Hox genes owned by the beast.
The Hox genes, which are not one strand of genes, but a whole complex of sequentially linked chains of like genes on the chromosome, sit on the chromosome directing the eyeballs toward the head and the asshole toward the back as fits the generally understood development of the beast in embryo. The paired parts of the bilaterally organized beast, if so organized, are sent their respective way by the Hox genes as well.
Hox genes were first testified to by an observation of anomalies in their normal workings, in mutations that made an antenna where the leg of a fly should be (antennapedia), for example, or the eye of a crustacean replaced instead by an antenna, or where a petal should be, a stamen.
I imagine generations of post-docs have played this trick and others like it on drosophila lineages, breeding whole misshapen batches of the things, putting an antenna where the leg should be or displacing the eye from here to there on the little beasts to confirm their own understanding of the techniques available to their craft which make it possible to reveal the curious play of the Hox genes in regulating the general disposition of the bodyparts, fore, mid and aft. The weight of supportable facts about Hox genes engendered by all these intrusive observations into the formal structure of drosophila is considerable, from what I understand.
Speaking of history, one of the things we can do with a phylogenetic analysis of the Hox cluster is see fascinating aspects of our ancient history. Since the genes are conserved, we can map correspondences between them within a lineage and in comparison with other lineages. We can surmise where duplications and deletions occurred, and most interestingly, since the genes are associated with morphological regions of the organism, we can speculate about how new additions to animal morphology occurred.
— P.Z. Myers at Pharyngula, on useful speculations
I do wonder about the ocean sunfish, though.
On my first marveling view of the beasts at the Monterey Bay Aquarium recently, I couldn't help but think of the first of the two posts written by P.Z. Meyers on the subject of Hox genes, which I'd idly glanced at and most certainly only partly comprehended some time before going to the Aquarium, and idly speculated while I watched them circulate in their huge tank of water, based only on my glancing familiarity with the facts of the matter, that the Hox genes of ocean sunfish must have some say in the abrupt wrapping up of the beast's form, which by most accounts of a fish would taper off to the agreeable formality of tail, but instead in the ocean sunfish comes to its curious bulbous compact halt just where the finality of a tail and all its associated bits might be expected to begin in what we commonly presume to be the layout of a fish. That the ocean sunfish has no scales is only a subsidiary marvel compared to its unique aft. It's just not a tail back there at all, by any measure.
But I don't really know if this truly marked divergence in the sunfish reaches right back into the nature of its Hox genes, snipping off the tail right there in the process of resolving the most basic inclination of its oriented parts, diverging before the tail even has a chance to be a place to put parts on a sunfish, or whether the tail that might be advanced by those genes is turned to its other end by the intercession of the successful play of some other bunch of genes, Hox or not, going on about their own simultaneous chemical business there in the embryo. If it's the Hox genes that are responsible, I can only say that the ocean sunfish must carry a highly distinctive bunch of them to do the remarkable job of rounding off it does.
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