In other words, Davescot made two mistakes in a single posting: first he confused citrate with the Lac operon and secondly, he incorrectly claims that 'Darwinian gradualism' is denied once again, because, after all, a stochastic event affects whether E. coli can digest lactose versus glucose. According to the ID 'argument', since chance and regularity can in fact explain the Lac Operon's switch, any design inference has been prevented. Which is why Davescot, calls it 'front loading' or a 'saltational' event. Let's first spend some time educating our confused Intelligent Design friends about the two studies, one which involve the work by Lenski et al Zachary D. Blount, Christina Z. Borland, and Richard E. Lenski Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli, Proc. Natl. Acad. Sci. June 10, 2008 vol. 105 no. 23 7899-7906This is contrary to Lenski's hypothesis that a series of dice throws, each making a small change towards ability to digest
— Davescotlactosecitrate, accumulate untillactosecitrate digestion is fully switched on. Darwinian gradualism is denied once again and we see a front loaded genome switch to a new mode of operation through a saltational event.
This paper was also discussed at Pandasthumb by PZ Myers and by New Scientist. Note that the paper clearly describes that it is discussing the evolution of E. coli's ability to digest citrate and not the Lac operon. Then again, scientific accuracy has never been a major concern amongst Intelligent Design Creationists and it help us explore how Intelligent Design fails to gain scientific relevance. And the second paper which discusses the Lac Operon Paul J. Choi, Long Cai, Kirsten Frieda, and X. Sunney Xie A Stochastic Single-Molecule Event Triggers Phenotype Switching of a Bacterial Cell Science 17 October 2008: 442-446.Abstract
The role of historical contingency in evolution has been much debated, but rarely tested. Twelve initially identical populations of Escherichia coli were founded in 1988 to investigate this issue. They have since evolved in a glucose-limited medium that also contains citrate, which E. coli cannot use as a carbon source under oxic conditions. No population evolved the capacity to exploit citrate for >30,000 generations, although each population tested billions of mutations. A citrate-using (Cit+) variant finally evolved in one population by 31,500 generations, causing an increase in population size and diversity. The long-delayed and unique evolution of this function might indicate the involvement of some extremely rare mutation. Alternately, it may involve an ordinary mutation, but one whose physical occurrence or phenotypic expression is contingent on prior mutations in that population. We tested these hypotheses in experiments that "replayed" evolution from different points in that population's history. We observed no Cit+ mutants among 8.4 × 1012 ancestral cells, nor among 9 × 1012 cells from 60 clones sampled in the first 15,000 generations. However, we observed a significantly greater tendency for later clones to evolve Cit+, indicating that some potentiating mutation arose by 20,000 generations. This potentiating change increased the mutation rate to Cit+ but did not cause generalized hypermutability. Thus, the evolution of this phenotype was contingent on the particular history of that population. More generally, we suggest that historical contingency is especially important when it facilitates the evolution of key innovations that are not easily evolved by gradual, cumulative selection.
This paper is also discussed by New Scientist and the reference to the work by Lenski may have confused Davescot. This confusion could have been easily avoided by actually reading the papers involved. Now that we have established that these were two very different studies: one involving the relevance of historical contingency in the evolution of E. coli's ability to digest citrate and the other involving the Lac operon switching from Lactose to Glucose digestion, a step which involves a stochastic (chance) component. So let's address Davescot's second flawed argument that the switch is a 'saltational' event. Let's first describe the Lac Operon in a bit more detail so that we can understand the ID creationist's confusion. The Lac Operon is an operon which controls the switching between glucose and lactose digestion.Abstract
By monitoring fluorescently labeled lactose permease with single-molecule sensitivity, we investigated the molecular mechanism of how an Escherichia coli cell with the lac operon switches from one phenotype to another. At intermediate inducer concentrations, a population of genetically identical cells exhibits two phenotypes: induced cells with highly fluorescent membranes and uninduced cells with a small number of membrane-bound permeases. We found that this basal-level expression results from partial dissociation of the tetrameric lactose repressor from one of its operators on looped DNA. In contrast, infrequent events of complete dissociation of the repressor from DNA result in large bursts of permease expression that trigger induction of the lac operon. Hence, a stochastic single-molecule event determines a cell's phenotype.
The Lac operon story is pretty straightforward, in the absence of Lactose, a repressor protein, encoded by the Lacl gene, which is always expressed, is allowed to bind with the Lac Operon, inhibiting the expression of the Lac genes. Thus during low Lactose availability, the Lac Operon is turned off. When Lactose is available in sufficiently high concentrations, a lactose metabolite binds with the repressor protein which now cannot block the expression of the Lac operon. However, there is an intermediate condition where both Lactose and Glucose are present. How does E. coli efficiently deal with this situation: if all E. coli switched to Glucose, an important energy source, Lactose, would remain unused, and if all E. coli maintained Lactose, the Glucose energy source would remain unused. But how to achieve this since all the bacteria are copies? Terry at Prometheus Untenured explainsIn its natural environment, lac operon is a complex mechanism to digest lactose efficiently. The cell can use lactose as an energy source, but it must produce the enzyme β-galactosidase to digest it into glucose. It would be inefficient to produce enzymes when there is no lactose available, or if there is a more readily-available energy source available (e.g. glucose). The lac operon uses a two-part control mechanism to ensure that the cell expends energy producing β-galactosidase only when necessary. It achieves this with the lac repressor, which halts production in the absence of lactose, and the Catabolite activator protein (CAP), which assists in production in the absence of glucose. This dual control mechanism, along with the ability to use lactose analogues in experiments, has lent itself to be studied in a laboratory setting extensively.
As the authors describeThe repressor is an allosteric protein, i.e. it can assume either one of two slightly different shapes, which are in equilibrium with each other. In one form the repressor is capable of binding to the operator DNA, and in the other form it cannot bind to the operator. According to the classical model of induction, binding of the inducer, either allolactose or IPTG, to the repressor affects the distribution of repressor between the two shapes. Thus, repressor with inducer bound is stabilized in the non-DNA-binding conformation. However, this simple model cannot be the whole story, because repressor is bound quite stably to DNA, yet it is released rapidly by addition of inducer. Therefore it seems clear that repressor can also bind inducer while still bound to DNA. It is still not entirely known what the exact mechanism of binding is.
In other words, once a rare occurrence of full disassociation happens under lactose/glucose conditions, it takes significant time for the repressor to 'find' the LacZ site and rebind. During this period of time, the Lac operon expresses significant bursts which then can cause additional binding of the lactose metabolite with the repressor protein and thus the cell switches to Lactose. And thus, science advances our knowledge while ID? Well, ask yourself how does ID explain this? By confusing it with citrate? Or by calling it 'saltational' or even 'front loading'? What better term to hide one's ignorance. But remember that they cannot call it 'design' since chance and regularity very well explain the Lac Operon's behavior.Why do complete dissociation events give rise to large bursts? Our group has recently shown that if a repressor dissociates from DNA, it takes a time scale of minutes for the repressor to rebind to the operator because the repressor spends most of its time binding to nonspecific sequences and searching through the chromosomal DNA. In addition, there are only a few copies of the tetrameric repressors . Such a slow repressor rebinding time, relative to transcript-initiation frequencies, would allow multiple copies of lacY mRNA to be made following a complete repressor dissociation event. Furthermore, in the presence of inducer, the nonspecific binding constant remains unchanged, but the affinity of the inducer-bound repressor to the operator is substantially reduced, rendering specific rebinding unlikely. The large burst that results from slow repressor rebinding is an example of how a single-molecule fluctuation under out-of-equilibrium conditions can have considerable biological consequences, which has been discussed theoretical- ly in the context of cell signaling and gene expression but has not previously been experimentally observed.
1
Source: Davescott comment on UcD hereJudge John E. Jones on the other hand is a good old boy brought up through the conservative ranks. He was state attorney for D.A.R.E., and Assistant Scout Master... extensively involved with local and National Boy Scouts of America, political buddy of Governor Tom Ridge (who in turnis deep in George W. Bush's circle of power), and finally was appointed by GW himself. Senator Rick Santorum is a Pennsylvannian in the same circles (author of the "Santorum language") that encourages schools to teach the controversy) and last but far from least, George W. Bush hisself drove a stake in the ground saying teach the controversy. Unless Judge Jones wants to cut his career off at the knees he isn't going to rule against the wishes of his political allies. Of course the ACLU will appeal. This won't be over until it gets to the Supreme Court. But now we own that too.
— Davescott
82 Comments
RobC · 19 October 2008
They should have stuck with politics-rabble rousing is easier than science. But seriously-the Lac Operon is now standard High-School biology:
http://books.google.com/books?id=RRcB6si_wV8C&pg=PA85&dq=AP+biology+Lac+Operon
To confuse the switch between the expression of genes (present in the E. coli genome) for glucose vs. lactose consumption, and the evolution of citrate metabolism is really telling.....
_Arthur · 19 October 2008
But, Lenski failed to surround its apparatus with GOD KEEP OUT signs, or to put it inside a pentagram.
How can we know the CIT+ mutation wan't caused by gods, angels or demons ?
Sunspiker · 19 October 2008
The really bizarre part is that someone has pointed out to DaveScot that it was citrate not lactose in the Lenski experiment, which he accepts, but then fails to change anything else about the post. The false link between the two experiments has been pointed out and it doesn't change his 'reasoning' one bit ? He just replaces lactose with citrate and it's all good again. Weird
PvM · 19 October 2008
James F · 19 October 2008
Breathtaking inanity strikes again.
Ouabache · 19 October 2008
I'm usually not one to throw insults around, but DaveScot has to be the most ignorant ID proponent out. He was the one who kept posting on UcD about the lame Obama birth certificate conspiracy theory. It's like he has no critical thinking skills at all. Who thought that it was a good idea to let him write on their blog?
PvM · 19 October 2008
DaveScot has managed something that many thought to be impossible, namely dragging down the quality of Uncommon Descent. Notice that this is hardly a simple task given the nature of the contributors who historically contributed at UcD such as Denyse O'Leary and William Dembski.
Note how there is little science left. Much of the space is wasted on silly topics regarding Global Warming and the recent political race. Even Dembski seems to have started to get annoyed by how these participants have dragged down UcD.
Sad really, but such seems to be the fate of so many ID sites.
Dale Husband · 19 October 2008
Worth repeating for the sheer amusement:
DaveScot made an absolute fool of himself here too:
http://www.uncommondescent.com/intelligent-design/id-is-not-science-because/
Can you beleive that?! If I had been William Dembski, I would have said to DaveScot: “You idiot! You just blew away our whole legal and scientific case! YOU’RE FIRED!!!"
PvM · 19 October 2008
Hey Dale, please clean up your act.
tacitus · 19 October 2008
I wouldn't be surprised if he was fired from Dell, but there is no evidence of that. His official story is that he is a "self-made millionaire".
Truth is, he sat on his ass while Dell threw stock options at him and the rest of the company's employees during the halcyon days of the mid-90s when Dell's stock price went stratospheric. There were a load of such Dellionaires around Austin at the time, so Mr. Springer is certainly nothing special in that regard.
Best thing you can say about DaveScot is that he sold his stock options at the right time -- I guess that makes him a legend in his own lunchtime.
gabriel · 20 October 2008
Frank J · 20 October 2008
Russell · 20 October 2008
DaveScot is an idiot!
In other breaking news, the sun rose in the east this morning!
Interrobang · 20 October 2008
PvM, you keep referring to DaveScot and various others of the ID crowd as "foolish," and I think that's not the right word. I don't think they're "foolish" at all -- DaveScot has a very nice sinecure on the wingnut welfare circuit, is far more famous than someone of his calibre would have been in actual science, has legions of adoring fans, and in all cases feels like he's actively shaping the public discourse (without having to be elected, educated, or even really know what he's talking about). That's hardly a "fool"; that's a skilled operator who knows just what he wants and has managed to achieve at least the most important parts of it (the stuff that pertains to enriching himself and stroking his ego). And as long as there's a paycheque and self-gratification in it for him, he's going to continue to push the ID line.
About the only thing that is going to stop guys like him is to defund them. Since they're largely funded by private donors, that is, the same billionaires who fund most of the religious right, I don't see how to do that.
Dale Husband · 20 October 2008
Eddie Janssen · 20 October 2008
Another weird thing is that Mr. Scot himself is responsible for almost half of the contributions to his own articles
Frank J · 20 October 2008
Science Avenger · 20 October 2008
This was my favorite Davescot moment, where he claimed the return of the ice measures to the global warming regression line somehow disproved global warming because it wasn't as catastrophic as the last few data points had indicated. It was such an idiotic display of someone seeing what he wanted to see, instead of what the data clearly showed, I still wonder to this day if he was really serious.
It's nice to see that site sink into total irrelevancy. They've earned it.
Timcol · 20 October 2008
I'm constantly puzzled why the likes of Dembski, a senior fellow at the Discovery Institute cannot get somebody with actual bona fide scientific qualifications to write on his blog. Instead we have this amazing motley crew of DaveScot, apparently some kind of former computer engineer who is at best an amateur, and by all accounts regularly shows serious gaps in his scientific understanding - and lately is using the blog as his own personal sounding-off platform against Obama; we have Denyse O'Leary - a self-described "journalist" and Coulter-wannabe, but without the wit or writing skills, and who really has absolutely nothing to say expect her constant & repetitive whining about the evils of "Darwinism".
Seriously, doesn't Dembski have the clout or influence to get somebody like Wells or Behe contribute to his Blog? At least these people are in possession of actual science degrees. It would at least lend some semblance of credibility to the site.
And the people who are allowed to comment (and they are very, very tightly controlled - I've been personally "expelled" at 3 times) not only do not in anyway provide a balanced viewpoint, but frequently quote Biblical scripture (and yet don't anybody dare to post a comment that criticises ID for being a faith-based initiative - if you do, you would be expelled from UD in heartbeat!)
Frank J · 20 October 2008
Brian · 20 October 2008
Henry J · 20 October 2008
_Arthur · 20 October 2008
Maybe Dave Scott is arguing that the CIT+ trait is due to a CIT-Operon, without any supporting evidence ?
I expect evidence will come in its own time, with the DNA sequencing of Lenski's Ecoli strains.
What will the Uncommon Dissenters do when the evidence show that the new CIT+ trait require multiple mutations, that were absent in the original (common) strain, and that are still absent in 9 of the 10 separate strains ? Acknowledge they were wrong ? That would be a first.
Henry J · 20 October 2008
Timcol · 20 October 2008
Paul Burnett · 20 October 2008
James F · 20 October 2008
Dale Husband · 20 October 2008
Stuart Weinstein · 20 October 2008
"So what is it. Is ID science or not science? It seems our opponents want to have their cake and eat it too by saying: “ID is not science because it cannot be falsified or verified. And by the way, ID has been repeatedly tested and shown to be false.”
I don't see that as an issue.
Its pretty simple really, where ID is testable it has been falsified.
Whats left is untestable hence ID is either failed science or untestable.
Not much of a talking point for ID, I think...
Stanton · 20 October 2008
NotedScholar · 20 October 2008
The rhetoric here about DaveScot is very negative and intolerant. This merely demonstrates the Creationists' most striking thesis - that Evolution is the root cause of fascism. Also, of terrorism:
http://archive.newsmax.com/archives/ic/2006/11/22/115532.shtml?s=tn
Science Avenger · 20 October 2008
There is nothing negative or intolerant about noting when someone is barking from his bunghole, and Davescot is a master. As for the evolution begets fascism thesis, the only thing striking about it is how otherwise intelligent people can con themselves into believing it. It belongs in the Rationalization Hall of Fame.
Richard Simons · 20 October 2008
Richard Simons · 20 October 2008
Dale Husband · 20 October 2008
Stanton · 20 October 2008
Dave Luckett · 21 October 2008
Tolerance? A wonderful virtue, towards that which should be tolerated, like religious or cultural difference, but worse than useless when confronting falsehood, dishonesty and malice. Negativity? What other response is appropriate when faced with intractible ignorance and wilful misrepresentation? Should these be warmly welcomed?
Nonsense! The only ethical response to these things is to call them what they are. To tolerate them is in itself unethical, no matter what the politics of the situation.
But this position is as far from fascism as it is possible to get. A fascist believes in the overarching power and authority of the state, which implies that personal ethics are subordinate to that power. A fascist would therefore lie, cheat and swindle if it would advance the state's cause - just as a creationist would do the same, in creationism's name. But science is concerned only with discovering facts. Lying, cheating and swindling is anathema to it. Of all things that would immediately cause a scientist to be dismissed from the company of science altogether and forever, giving false evidence is the surest, the swiftest and the most dire.
Yet creationists, from the Paluxy "footprints" to the "Ica stones", from the dust on the moon to the "anomolous fossils", from the saltiness of the seas to the "polonium rings" to radiometric dating, have always and throughout lied, misrepresented, swindled and led false evidence.
And we are supposed to tolerate this and be positive about it? Only a fool would think so.
Paul Burnett · 21 October 2008
Paul Burnett · 21 October 2008
James F · 21 October 2008
Frank J · 21 October 2008
eric · 21 October 2008
PvM · 21 October 2008
dhogaza · 21 October 2008
PvM · 21 October 2008
I looked at 'NotedScholar's' site. Fascinating 'rants' against infinity and relativity. I can only conclude that notedscholar's choice of alias is 'tongue in cheek'.
PvM · 21 October 2008
For a recent paper by Mann on Global Warming, see the article at RealClimate, one of the better climate sites.
The paper
Michael E. Mann, Zhihua Zhang,Malcolm K. Hughes, Raymond S. Bradley, Sonya K. Miller, Scott Rutherford, and Fenbiao Ni Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia PNAS Published online before print September 2, 2008
Mike · 21 October 2008
eric · 21 October 2008
iml8 · 21 October 2008
Sam Cody · 21 October 2008
It took over 30,000 generations for an e-coli variant to develop the ability to use citrate for nutrition.
If it took this many generations for bacteria to develop something useful-would it take a near infinity for slower-breeding creatures (including us) to innovate?
That appears to bode ill for the ability of chance mutations/natural selection to explain (single-handedly) all the evolutionary change that is evident in geological history.
I therefore invite the community to link me up to papers, blog entries,etc that explain how evolution surmounted this apparent speed issue in slower-breeding forms of life.
I would love to do the reading and learn something.
Many thanks!
Sam Cody
fnxtr · 21 October 2008
There's this thing called a "library". Maybe they have them where you are?
fnxtr · 21 October 2008
It took 30K generations for e.coli to generate that particular ability. In the real world the variables are myriad, so any genetic variability has a chance of being an advantage.
Glen Davidson · 21 October 2008
http://tinyurl.com/2kxyc7
Larry Boy · 21 October 2008
Dave Luckett · 21 October 2008
And bacteria do not reproduce sexually, so that the opportunities for descent with modification are less. There is good reason to believe that this is in fact the very reason for sexual reproduction - that it introduces more possibilities for favourable variations. (And unfavourable ones, too, but these are weeded out by natural selection.) All else being equal, one would therefore expect a sexually-reproducing organism to respond to environmental change faster than an asexually-reproducing one. But bacteria reproduce with astonishing speed, which more than makes up for it, and some environments do not change, or change very slowly, which allows the advantages of asexual reproduction to assume greater weight - as is the case with the bdelloid rotifers. These have apparently returned from sexual to asexual reproduction.
Larry Boy · 21 October 2008
Sam Cody · 21 October 2008
Henry J · 21 October 2008
tresmal · 21 October 2008
Another point is that this and similar studies start with a single strain of bacteria (for the very good reason of reducing variables.) This stacks the deck against natural selection by eliminating horizontal gene transfer. Or at least eliminates the point of it. A more natural setup would start with several diverse strains of bacteria all negative for citrate metabolism and allow for genetic exchange. The thinking here is that a larger extended genome would allow for quicker results. This would come at the cost, however, of making the researchers' job much more difficult.
PvM · 21 October 2008
Dale Husband · 21 October 2008
Sam Cody · 21 October 2008
Sam Cody · 21 October 2008
Dave Luckett · 21 October 2008
Mike says:
"But why? Yes, we're being intolerant, but why?"
Why? Because we want to know the truth about the Universe we inhabit. We are vitally interested in factual knowledge about the real world, as attested by empirical evidence.
And why do we want to know the truth? Well, because it's the truth, dammit! Jesus of Nazareth remarked that we would know it, and it would set us free. So it does; so it has; so it will. Nevertheless, it is more than merely liberating. Truth is a good and righteous thing in and of itself, and it can be discovered and demonstrated by empirical observation and unfettered reason. Yes, the method of science is cool observation of fact; but at its heart there lies a passion for knowing the truth.
So science is outraged by the lies, disinformation, propaganda, falsehood, prejudice and misrepresentation which are the currency of creationism - and so it should be. Intolerance is the only self-consistent response to such things. It is thus the only ethical response to them.
That's why.
fnxtr · 21 October 2008
A more accurate understanding of reality is also a survival advantage. Rather than sacrifice the virgin to the volcano god, let her contribute to the gene pool. :-)
fnxtr · 21 October 2008
sorry, Sam, it's never easy to tell whose questions are genuine and whose are the beginning of a troll. I hope your questions are being answered to your satisfaction.
Henry J · 21 October 2008
Glen Davidson · 21 October 2008
http://tinyurl.com/2kxyc7
Stanton · 21 October 2008
Dave Luckett · 22 October 2008
Stanton, Komodo dragons, with or without incest, make me cringe just on general principles. And now I have learned a number of things that I would not have learned if I didn't read and post on this blog. Thank you.
Stanton · 22 October 2008
NotedScholar · 22 October 2008
NotedScholar · 22 October 2008
NotedScholar · 22 October 2008
Well this wasn't very productive, as all it was was elite mockery and PhD-ism. I shall exit from this debate, knowing that my arguments hold up even after all your scrutiny.
BTW one commenter, PvM, said I had "rants" on my blog against relativity, which is a complete fabrication. Check for yourself.
iml8 · 22 October 2008
NARF!
Paul Burnett · 22 October 2008
Richard Simons · 22 October 2008
PvM · 22 October 2008
Science Avenger · 22 October 2008
What the Hell is PhDism? The nutty notion that the more one studies something, the more one tends to understand it? Wouldn't that the make your position essentially intellectual homeopothism?
eric · 22 October 2008
EoRaptor013 · 24 October 2008
бреннемэн · 21 November 2008
Only lacZ and lacY appear to be necessary for lactose catabolism and is inversely proportional to that of glucose. The second control mechanism is a response to glucose. They are oriented in the same direction immediately adjacent and are not produced by the bacterium when lactose is unavailable as a carbon source. In the absence of glucose Cyclic adenosine monophosphate (cAMP) is a signal molecule whose prevalence is inversely proportional.