Hang on, close your eyes, don’t click on the “Read on…” link at the bottom of this post; I’ve put an obscene picture of explicit prurience below the fold. It might arouse you to engage in wild monkey-sex in your workplace, or worse, inspire horrific violence. Don’t view it if you are a sensitive person!
I just learned (via John Lynch) about a paper on cetacean limbs that combines developmental biology and paleontology, and makes a lovely argument about the mechanisms behind the evolution of whale morphology. It is an analysis of the molecular determinants of limb formation in modern dolphins, coupled to a comparison of fossil whale limbs, and a reasonable inference about the pattern of change that was responsible for their evolution.
One important point I’d like to make is that even though what we see in the morphology is a pattern of loss—whale hindlimbs show a historical progression over tens of millions of years of steady loss, followed by a near-complete disappearance—the molecular story is very different. The main players in limb formation, the genes Sonic hedgehog (Shh), the Fgfs, and the transcription factor Hand2, are all still present and fully functional in these animals. What has happened, though, is that there have been novel changes to their regulation. Even loss of structures is a consequence of changes and additions to regulatory pathways.
My metaphysico-theologo-cosmolonigology is all discombobulated now—Dave has found an artificial enhancement of the spectacle perch that implies that perhaps this is not the best of all possible worlds.
It seems that Skeptico has a copy cat—a guy who goes around posting under the name Skeptico, and who has started a blog of his own at skeptico.blogspot.com—but I don’t think anyone will confuse the two. This new Skeptico is an evolution denier and global warming denier, and is your typical run-of-the-mill dumbass reactionary. He’s more of an anti-Skeptico…no, a mini-anti-Skeptico.
I took a look at the work of the pseudo-Skeptico, and was surprised at his ignorance.
Well, it so happens that I am quite new to the ID-EVO debate, indeed to ID literature itself (although the controversy has intrigued me for many years). I’ve just only recently finished Behe’s “Darwin’s Black Box.” This whole intriguing field of microbiological complexity, replete with innumerable individual irreducible complexities, is very fascinating. And I am sure that not a few level-headed people, upon reading that book, must have thought it nothing short of a succinct and irrefutable refutation of neo-Darwinism. For, indeed, that is precisely what it is.
Nevertheless, how many hardcore Darwinists will change their positions as a result? Few, I daresay. Very few. Because, at the end of the day, to relinquish this cherished theory requires an act of will that unavoidably involves a whole phalanx of personal vested interests with philosophical, moral, religious, teleological, and most emphatically social ramifications (friends could be lost, you see, or maybe even a mentor). “Science”–howsoever many times that encumbered shiboleth be invoked, howsoever sanctimoniously, howsoever shrilly and desperately–is not the issue here. Not for them. Not for the believer. Not now. Not ever.
There’s an admission that he’s new to the debate, and has only just now read Behe’s crappy little book, and now he thinks the debate is all over. He expects, though, that scientists will refuse to give up their tired old ideas because, unlike him, they aren’t open-minded and are tied up in the establishment. Everything he says is wrong. The book is not irrefutable; quite the contrary, I know a few biologists who have read it (not many, though, since the book’s cheesy reputation precedes it), and they remain unconverted because the science in the book is badly done. Irreducible complexity is a crock. Behe’s testimony in Dover was a farce. His attempts to ‘disprove’ evolution since have been laughable.
The science is against him, which makes that last paragraph I quoted above a fascinating example of creationist projection.
The Tangled Bank will be appearing at Science and Politics tomorrow. Get your submissions in to Coturnix, me, or host@tangledbank.net now!
Just wait—I have an inside scoop on amazing insights into biology that will definitely win me a Nobel prize. I have to thank Eve for leading me to this incredible prophetic knowledge.
Chad reports a not-so-subtle message from a science conference:
The annoying thing was the peripheral message– she took pains to state several times that both Democrats and Republicans in Congress support science, in a tone that basically came across as chiding us for thinking otherwise. That was annoying by itself, but at the very end of the talk, she specifically warned against taking partisan positions, citing the letter supporting John Kerry that was signed by a couple dozen Nobel laureates as something that made it harder to keep science funding. She said that after that, when she met with administration officials about budget matters, she could see them thinking “Damn scientists…”
When the government says or does something scientifically stupid, it is our solemn duty to go along with it.
I’m going to briefly summarize an interesting new article on cnidarian Hox genes…unfortunately, it requires a bit of background to put it in context, so bear with me for a moment.
First you need to understand what Hox genes are. They are transcription factors that use a particular DNA binding motif (called a homeobox), and they are found in clusters and expressed colinearly. What that means is that you find the Hox genes that are essential for specifying positional information along the length of the body in a group on a chromosome, and they are organized in order on the chromosome in the same order that they are turned on from front to back along the body axis. Hox genes are not the only genes that are important in this process, of course; animals also use another class of regulatory genes, the Wnt genes, to regulate development, for instance.
A gene can only be called a Hox gene sensu stricto if it has a homeobox sequence, is homologous to other known Hox genes, and is organized in a colinear cluster. If such a gene is not in a cluster, it is demoted and called simply a Hox-like gene.
Hox genes originated early in animal evolution. Genes containing a homeobox are older still, and are found in plants and animals, but the particular genes of the Hox system are unique to multicellular animals, and that key organization arrangement of the set of Hox genes in a cluster is more unique still. The question is exactly when the clusters arose, shortly after or sometime before the diversification of animals.
If you take a look at animal phylogeny, an important group are the diploblastic phyla, the cnidarians and ctenophores. They branched off early from the metazoan lineage, and they possess some sophisticated patterns of differentiation along the body axis. We know they have homeobox containing genes that are related to the ones used in patterning the bodies of us vertebrates, but are they organized in the same way? Did the cnidaria have Hox clusters, suggesting that the clustered Hox genes were a very early event in evolution, or do they lack them and therefore evolved an independent set of mechanisms for specifying positional information along the body axis?
My schedule for the first 3 weeks of June was looking hectic, so it was actually with some sense of relief that I flipped open the PDA and scribbled in the fact that a comet will smash into the earth on 25 May.
I haven’t yet been confident enough to erase all my post-apocalyptic appointments, though. I figure the cataclysm will do that for me.
Rabbits are the most freaky of all mammals (right, Chris?) They’re thriving, though—they’re all over my lawn, and if this summer is anything like last year, I’ll have to go out about once a week and scrape one off the road running by my house.
I did not know that interesting fact about their scrotum, though.
