Christopher Hitchens was impressed by the existence of blind cave organisms, and wrote that they argue against a linear progression in evolution. He’s quite right; creationism doesn’t explain why their god tossed in to salamanders and fish a collection of complex developmental mechanisms that the animals simply throw away and do not use. Evolution does — descent from a sighted ancestor explains how blind cave animals can still possess the machinery for a lost organ.

Do you think the Discovery Institute would let this challenge pass by? Of course not. They put their top man on the job, so Casey Luskin wrote a rebuttal. After a long weekend and before a busy day of work, it always makes me happy to find a new Luskin screed — they’re so dang easy to shred. Here’s his devastating critique:

Hitchens, Dawkins and Carroll can have all the evidence they want that the neo-Darwinian mechanism can mess things up, turn genes off, and cause “loss-of-function.” No one on any side of this debate doubts that random mutations are quite good at destroying complex features. Us folks on the ID side suspect that random mutation and natural selection aren’t good at doing very much more than that. And the constant citations by Darwinists of “loss of function” examples as alleged refutations of ID only strengthens our argument.

The claim that evolution can’t create new features is one of the oldest and most tired fables in the creationist playbook — note that that link cites the Watchtower Bible and Tract Society and Henry Morris. It’s false. In this case, their superficial knowledge also trips them up. The loss of eyes seems like a clear-cut case of degeneration…but when you look deeper, it’s not.

The best studied case is the comparison of blind and sighted forms of Astyanax, a fish that has species that live in surface waters and have eyes, and others that live in caves and have lost them.

The Jeffery lab has worked out the molecular details of eye loss, and it isn’t as simple as messing things up, turning genes off, and causing loss-of-function mutations. To the contrary, all the genes for eyes are there and functional in the blind species. Simply transplanting small bits of organizing tissue from species with eyes to embryos of the blind forms can recruit host tissue to build a complete functional eye — that tells you the genes are still there. A comparison of gene expression patterns between the two also reveals that the blind species actually upregulates a majority of its developmental genes. Contrary to what Luskin claims, this is a positive change in development, not a loss, but an active suppression of eye expression.

What’s actually going on is that there is an increased expression of a gene called Sonic hedgehog, which causes an expansion of jaw tissue, including both the bones of the jaw and the array of sensory structures on the ventral surface — this is an adaptation that produces stronger jaws and more sensitive skin, what the fish finds useful when rooting about in the dark at the bottom of underground rivers to find food. The expansion of Shh has a side effect of inhibiting expression of another gene, Pax-6, which is the master regulator of eye development. Loss of eyes is a harmless (if you’re living in the dark) consequence of selection for better tactile reception.

Pathetic, isn’t it, how abysmally wrong Luskin can be? His conclusion is even sillier.

Meanwhile, ID proponents seek to explain a far more interesting aspect of biological history: the origin of new complex biological features. Despite his quotation of Michael Shermer on the evolution of the eye, Hitchens has yet to do that.

Actually, despite claiming that ID proponents are trying to explain the origin of biological features, Luskin hasn’t used this opportunity to even try. He can’t; “Designer did it” is not an explanation.

While we were all distracted by the recent Crackerclysm, we shouldn’t forget the shenanigans in Texas. The hearings have begun, led by the mad creationist dentist, Don McLeroy, and the Texas Board of Education is gearing up to dilute science education further, and introduce new silliness. Stand up for science with the Texas Freedom Network!

One of the best things about following the antics of creationists is that it gives you a better appreciation of the creative power of the human mind…which isn’t anywhere near as powerful as reality. Here’s another example of creationist rationalization that doesn’t hold up well under even casual inspection.

With the notable exception of the American Bison most mammals have two separate pleural or lung cavities. As we all know, one side of our chest can be penetrated collapsing that lung, but the other side remains intact and the remaining lung can support life. The bison has what is called an incomplete mediastinum, that is there is but one pleural cavity containing both lungs. Thus the problem for the Native bow hunter with or without a horse is solved. An arrow must only penetrate the chest at any point and both lungs collapse. The fatally wounded animal would only continue a few yards providing unlimited food, clothing and tools. Before the availability of horses bison could be shot by stealth from a blind or other hiding place. One problem is solved yet another serious comes to mind…a problem seldom mentioned, yet demanding an answer.

The problem is for the evolutionist. Other than providing food for hungry people, of what selective advantage is an incompletely divided mediastinum? From an evolutionary sense this makes absolutely no sense. Indeed conventional wisdom would argue for its elimination from the gene pool. Yet it did remain and fed a continent of Native American for centuries. It must indeed require faith and dedication to remain an evolutionist. I am glad I know the Creator of Bison and Native Americans. You can know Him too.

So, wait…God hates bison? Doesn’t this create a logical problem for the creationist, in that God has made the primary large game animal targeted by the Native Americans exceptionally fragile?

And let’s question that assumption: bison aren’t particularly weak, and there’s no reason to assume that selection would work to promote the evolution of dual compartments in the chest cavity — that’s almost certainly an embryological accident in the first place. How many wild animals are running around with only one lung? Not many. If you’re attacked in such a way that your chest cavity is perforated, the only difference between a separated and unseparated mediastinum is whether your death will be slow or quick.

And of course, I thought the Hebrews were the chosen people. How come God didn’t give the Middle East a population of big game animals they could knock over with a good sharp poke?

Canadian Cynic has a nice sharp rebuttal: “…if God had really cared about native Americans, he might have given them immunity to smallpox.”

Perhaps you’ve been wondering how creationists handle new research in biology. We’ve already seen how Conservapædians cope: by denial, bleating for the data, and threatening lawsuits, basically by putting on a freak show to distract from the evidence. Facing the same data from the Lenski lab, Answers in Genesis plays a different game: we knew it all along. It isn’t what scientists say it is. We’ll just use the scientific explanation with a few of our buzzwords tossed in.

Here’s AiG’s conclusion about the work of Richard Lenski on evolution in E. coli. It misses the main point — the demonstration of historical contingency — but it basically parrots and accepts the standard scientific understanding, with a few exceptions (they’ll be easy to spot — wherever the text lapses in Mr Gumby-esque assertions, that’s the creationism bellowing.)

Mutations which lead to adaptation, termed adaptive mutations, can readily fit within a creation model where adaptive mechanisms are a designed feature of bacteria allowing them to survive in a fallen world. Since E. coli already possess the ability to transport and utilize citrate under certain conditions, it is conceivable that they could adapt and gain the ability to utilize citrate under broader conditions. This does not require the addition of new genetic information or functional systems (there are no known “additive” mechanisms). Instead degenerative events are likely to have occurred resulting in the loss of regulation and/or specificity. It is possible that the first mutations or potentiating mutations (at generation 20,000) were either slightly beneficial or neutral in their effect.

Given the selective pressure exerted by the media of a limited carbon source (glucose) but abundant alternative carbon source (citrate), the cells with slightly beneficial mutations would be selected for and increase in the population. Alternatively, if the mutational effects were neutral the cells with these mutations might remain in the population just by chance, since they would not be selected for or against. Around generation 31,500 additional mutations enabled the cells to utilize citrate and grow more rapidly than cells without the adaptive mutations. Adaptive mechanisms in bacteria work by altering currently existing genetic information or functional systems to make the bacteria more suitable for a particular environment. Further understanding of Lenski’s research is valuable for development of a creation model for adaptation of bacterial populations in response to the adverse environmental conditions in a post-Fall, post-Flood world.

Cunning, eh? From denying that beneficial mutations exist at all, we’ve got them to the point where they admit that they can be found…they’re just calling them “adaptive mutations”, with the implication that these are like the physiological mechanisms that allow organisms to engage in short-term changes in behavior or metabolism. Of course, they’re still croaking on about The Fall, which never happened, and there is that bit at the beginning about an absence of new genetic information that is a complete lie, but it’s progress. It’s still dishonest misrepresentation, but they know enough to let a shadow of the real science peek through, for verisimilitude’s sake, at least.

The creationists are evolving. Or perhaps they’d prefer that we say they’re “adapting”.