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Bacterial Flagellum: Appearances Can be Deceiving

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July 29, 2010 Tags: Design

Today's entry was written by Kathryn Applegate. You can read more about what we believe here.

If any symbol captures the spirit of the Intelligent Design movement, the bacterial flagellum is it. Beautiful artistic renderings so frequently adorn ID books, blogs, and videos that ID critic Ken Miller has called it the “‘poster-child’ of the modern anti-evolution movement.”

For many decades, the exquisite structure and function of the bacterial flagellum was unappreciated outside the scientific community. We can thank ID leader Michael Behe for changing that. His 1996 book Darwin’s Black Box introduced the world to the flagellum and at the same time exalted it an impassable obstacle to Darwin’s theory of evolution. Behe used the flagellum to illustrate his principle of irreducible complexity—the idea that some features of life are too complex to have developed gradually. These features, Behe argued, are best explained as the product of a Mind.

Today we’ll take a brief look at the flagellum and see why it remains such a powerful icon for the ID movement. In future posts we’ll consider whether the biology of the flagellum makes more sense in light of an evolutionary or a design paradigm.

What is the bacterial flagellum?

Bacteria typically live in aqueous (watery) environments and need to swim to find food and evade enemies. To accomplish this feat, they use a truly marvelous apparatus, the flagellum.

Bacterial flagella are long, whip-like tails protruding from a base tethered in the cell wall. The base contains a rotary motor powered by an electrochemical gradient: a mismatch in the concentration of hydrogen ions across the membrane provides the energy needed to power the motor. The strength of the gradient controls the speed of rotation; typically the propeller tail spins in the range of several hundred to a thousand RPM. As a result, bacteria can travel up to 60 cell lengths per second! The shape of the propeller and the ability of the rotor to change directions allow the bacterium to either swim in a precise direction or randomly tumble to reorient when needed. The number and arrangement of flagella can vary dramatically by species, yielding great diversity in the way bacteria get around, but the basic unit is the same.

While the cartoon above makes the flagellum look simple enough, in reality the machine is quite complicated. Just like an outboard motor, the flagellum has a rotating element (rotor) and a stationary element (stator) embedded in the cell wall and membrane. These elements are connected to the flexible filament by a hook (see cartoon at left). The parts list for these three components includes about 40 different proteins.

A powerful analogy

Why do some argue that the bacterial flagellum is the product of intelligent design rather than evolution? For starters, it looks like something known to be designed—the outboard motor. ID proponents like Behe are not alone in recognizing the parallel. In 1998, structural biologist David DeRosier marveled, “more so than other motors, the flagellum resembles a machine designed by a human.”

The resemblance is so striking, we find it difficult to resist extending the analogy to how the flagellum originated. We know that all outboard motors are designed by intelligent engineers; the parts are carefully crafted to work together for an intended purpose. The bacterial flagellum also has many well-matched components. Together they perform the same job as the outboard motor—swimming. Since the flagellum wasn’t designed by human engineers, it seems only reasonable to infer that it was designed by Someone Else.

But appearances can be deceiving. Look carefully at the photograph below:

It’s beautiful, isn’t it? A light wind blows playfully, rustling the tall grass. The red rocks in the distance radiate heat from the day. I’d love to be there to watch the clouds unfurl in all the majesty of a prairie sunset.

The only problem is, the place doesn’t exist. This piece of art is not a digitally altered photo, or even a realistic-looking painting. It’s a real scene in miniature, created by 26-year-old artist Matthew Albanese out of faux fur (for the grass), cotton wool (clouds) and tile grout (rocks).

Don’t believe me? If you watched Albanese in action, you would immediately understand how he created this amazing image. Check out his studio setup for making realistic cloud images from a suspended tuft of cotton:

What does this have to do with the bacterial flagellum?

The example above illustrates how deceptive appearances can be. The landscape in the photograph appears to be entirely natural, but every detail is meticulously designed. In contrast, the bacterial flagellum looks entirely unnatural. It seems much too complicated to have arisen through random mutation and natural selection. Yet as we will see in future posts, even the most iconic irreducibly complex system, the bacterial flagellum, can be understood in light of these evolutionary processes.

It’s worth pointing out that understanding the creative process magnifies, rather than diminishes, the work of the artist. I don’t imagine many people fly into a rage when they learn how Matthew Albanese creates his beautiful photographs. Rather than feel deceived, they feel amazed! In the same way, when we see how God created all the marvelous forms of life through an extended dance of natural processes—his laws—the appropriate reaction is not dismay, but worship.


Kathryn Applegate is Program Director at The BioLogos Foundation. She received her PhD in computational cell biology at The Scripps Research Institute in La Jolla, Calif. At Scripps, she developed computer vision software tools for analyzing the cell's infrastructure, the cytoskeleton.

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Daniel Mann - #24557

August 5th 2010

Penman,

I certainly agree with you here—“the church, qua church, should [not] be preaching any scientific theory of origins as “things most surely believed among us”. It should be preaching the faith of Christ, & giving space to discuss the science.”

However, while your appalled by the church using unChristian methods to slur those who believe in evolution, I’m appalled by the sight of evolution being imposed upon Bible interpretation to the great determent of the church—to the point that everything must be reduced to figurative language in order to accommodate Darwin. Even the NT quotations of Genesis must be emptied of their literal - historical content.

But it doesn’t stop there. The concepts of the Fall, sin, the Second Adam all must be modified in such a way to coincide with evolution and the gradual appearance of man. I hope you can fathom my consternation.


nedbrek - #24560

August 5th 2010

penman, I don’t believe YEC is necessary for salvation.  However, I think your origin story says a lot about God, and we should try to have as accurate a picture of God’s character and nature - which are things the Bible is clear about.

Re. geocentricity - thanks to Einstein, we can have a reference frame with a fixed, central Earth

Seriously, I am unaware of any theological implications of a universe centered on the Earth or not.  The biggest argument seemed to be “my interpretation must be correct”, which is not my stand on YEC.  I believe YEC, not because it is easy, but because it is the only stand which harmonizes everything I know about God with what evidence is available.

Re common descent with modification, if you mean wolves bring forth Great Danes and chihuahua - yes.  But I don’t think we should say all living things share a common ancestor.  That does not match the evidence (and it makes for bad theology).


nedbrek - #24576

August 5th 2010

Jon, I don’t believe in the fixity of species (not many people do).  I do believe that plants and animals “bring forth after their kind”.  That is what the evidence shows, too.

I am a skeptic when it comes to macro-evolution (I’m from Missouri, show me).  I don’t need to see an amoeba (any asexual one-cell really) become a paramecium (sexual one cell, or any multi-cell) in one step.  I would like to see something impressive though.  A bacteria that feeds on one protein bringing forth bacteria that feed on a different protein doesn’t impress me.


Daniel Mann - #24581

August 5th 2010

Jon,

I agree that our use of the term “figurative” requires some elaboration. So let me return to Matthew 19:4-6:

“Haven’t you read,” he replied, “that at the beginning the Creator ‘made them male and female,’ and said, ‘For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh’? So they are no longer two, but one.”

I think that Jesus is clearly endorsing the historicity of Gen 1 and 2. However, there are figurative elements. Although Jesus doesn’t cite it, man is created in the image of God. This is clearly figurative, since God is Spirit. However, the NT also affirms this figurative usage by defining what “image of God” is all about (Eph. 4:23-24). I think that this NT commentary has to be definitive for us.

Similarly, Jesus cites how God historically made the two into “one flesh.” This is clearly figurative. We just don’t see the man bound physically to his wife. The two flesh must refer to a spiritual reality, and this is confirmed by Paul who likens matrimonial union to the spiritual Body of Christ (Eph. 5:31). However, these figurative elements do nothing to undermine the historicity of the Gen. account, which the NT clearly endorses.


Daniel Mann - #24583

August 5th 2010

Jon,

One last thought—- I do respect the depth of your thought and look forward to looking at your “humble piece.” My prayer is simply that rather than trying to rework Scripture in accordance with the modern scientific consensus, you would consider reworking the former according to the light of Scripture (2 Cor. 10:4-5).

By not doing this, you risk the displeasure of our God (Job 42:7-8) and injury to His people. By doing this, you risk being considered foolish and irrelevant by society—the lot that we Christians have always had to endure.


penman - #24586

August 5th 2010

Daniel Mann:

“I’m appalled by the sight of evolution being imposed upon Bible interpretation to the great determent of the church—to the point that everything must be reduced to figurative language in order to accommodate Darwin. Even the NT quotations of Genesis must be emptied of their literal - historical content.”

There, you alight on a matter that commands no uniformity of judgment among ECs. ECism isn’t monolithic. I’m committed to a belief in a historical Adam, on the strength largely of the NT witness (not just Rom.5, either). I think he was the federal head of image-bearing humanity, & that there was a collective historical fall. But I see no good reason why the original Adam-headed race shouldn’t have been brought forth into being by God through evolutionary processes, at least regarding their physical constitution (the imago dei itself I’d see as given supernaturally - there’s a passage in C.S.Lewis’s The Problem Of Pain that expresses it very well).

Apart from a historical Adam, what other biblical teachings do you think are illegitimately vaporized away into mere allegory by some ECs in order to appease Darwin?


Daniel Mann - #24596

August 5th 2010

Penman,

Your views are more acceptable than the views of most ECs with whom I’ve dialogued at BioLogos. Representative of most of them is “Saving Darwin” by Karl Giberson:

•  “Acid is an appropriate metaphor for the erosion of my fundamentalism, as I slowly lost confidence in the Genesis story of creation and the scientific creationism that placed this ancient story within the framework of modern science….[Darwin’s] acid dissolved Adam and Eve; it ate through the Garden of Eden; it destroyed the historicity of the events of creation week. It etched holes in those parts of Christianity connected to the stories—the fall, “Christ as the second Adam,” the origins of sin, and nearly everything else that I counted sacred.” (9-10)

When does a belief-system cease being Christian? I’m not sure. Are you?


Jon Garvey - #24597

August 5th 2010

@Daniel Mann - #24583

Just one thought on this. Both the natural world and God’s word predate our current understanding. So when Christians finally reinterpreted the Bible because Copernican science made their understanding untenable, what they were actually doing was letting God’s old “natural” truth, newly rediscovered by man, guide them to the more authentically original meaning of Scripture.

Always remember that both science and theology are the work of man, whilst both the natural world and Scripture are the work of God.


Daniel Mann - #24599

August 5th 2010

Jon,

While I agree that we should be open to creation knowledge guiding Biblical interpretation, I must draw the line where this “knowledge” seeks to OVERRULE or impose itself upon Biblical interpretation.

Although I agree with you that “science and theology are the work of man, whilst [good KJ!] both the natural world and Scripture are the work of God,” the Bible comes with its own interpretative statements, unlike the physical world. The Bible says things like, “This is why…” or “For this reason…” Thus, we are a step or two ahead when interpreting the Bible.


penman - #24608

August 5th 2010

Daniel Mann:

“Your views are more acceptable than the views of most ECs with whom I’ve dialogued at BioLogos.”

Most people think I’m a terrifyingly narrow-minded Grand Inquisitor of traditional orthodoxy - until they discover I believe in evolution, & then I’m a spineless compromising liberal jelly-bubble. Ach, you can’t win.

Having looked through all the items in the Karl Giberson quote (I don’t agree with everything he says, but he’s usually right about science, in my meaningless estimation), there was only one item that was seriously different from a historical Adam, viz. “the historicity of the events of creation week” - which I understand to mean that Gen.1 is not univocal prose history. Well, I agree with Karl on that. I think Gen.1 is a quasi-poetic chant, whose overriding purpose is theological in nature: a polemic against ancient near eastern Pagan cosmologies & cosmogonies, in the interests of establishing a pure monotheism of creation.

But that doesn’t sever me from the orthodox tradition, since “theological” rather than “prose history” readings of Gen.1 had a secure place among the early church fathers (notably Augustine).

I can’t see this as remotely on the same level as the status of Adam.


Daniel Mann - #24615

August 5th 2010

Penman,

You wrote, “I think Gen.1 is a quasi-poetic chant, whose overriding purpose is theological in nature: a polemic against ancient near eastern Pagan cosmologies & cosmogonies, in the interests of establishing a pure monotheism of creation.”

Perhaps you’re right. I too see a polemic in Genesis, but elucidating how God worked historically might serve as the best polemic?

I know what you mean about how you can’t win. I receive so much abuse it’s incredible. I thank God that He’s strengthened me, but it still hurts.


Jon Garvey - #24724

August 6th 2010

@Daniel Mann - #24599

I agree to a point re advantages of interpreting a text over a universe.

But on the other hand the laws of nature seem unchanged over time and distance, whilst human thought patterns undergo great cultural shifts. So it’s not as clear to me, for example, why seething a kid in its mother’s milk has moral connotations as it would be to an Israelite. Whereas the speed of light or the annual deposition of polar ice don’t get influenced by being surrounded by Canaanites.


penman - #24738

August 6th 2010

Daniel Mann:
“I too see a polemic in Genesis, but elucidating how God worked historically might serve as the best polemic?”

Yes, God COULD have given us a straight, ordinary, down-to-earth, prosaic description of how & when He created the universe. But I don’t think He did give us that. The style of Gen.1 just isn’t like the style of the more prosaic historical narratives of (say) Judges or the synoptic Gospels. There’s an exalted majesty, a semi-poetry, a highly complex verbal & number-based intricacy (this last doesn’t come out in English). I don’t think the writer would have used this style, if he intended to give us that simple, factual, “I’m-from-Missouri” sort of account that young earth-ism finds in Gen.1. It would me like me being sworn in as a witness in a trial, & then spouting Paradise Lost in the witness box. The judge would be quietly texting the nearest mental asylum…

One of the best defences of the view I’m suggesting is in the book “In The Beginning” by distinguished French Reformed scholar, Henri Blocher. Highly recommended.

Meanwhile “creationists” of all stripes - YEC, OEC, ID, EC - should certainly stop abusing each other! (Sounds like a Lovecraftian god - the Abominable Yecoec-Idec)


Daniel Mann - #24744

August 6th 2010

Jon,

Don’t you think that we have a similar problem with physical world interpretations—that the effects of the operation of one law are impacted by other laws: boiling of water at different altitudes?


Daniel Mann - #24745

August 6th 2010

Penman,

I’m all for not abusing one another, even though there are terribly weighty issues at stake here.

Indeed, the style of Genesis is somewhat different than that of Judges and contains more figurative language perhaps, but I don’t think that its figurativeness argues against its historicity:

1.  The NT speaks strongly in favor of the fact that the recorded events took place!

2.  Continuity: There are continuous linguistic and thematic elements linking the 1st several chapters with the Abe—Joseph narratives.

3.  The genealogies argue powerfully for historicity.

4.  No verses indicate that these accounts were not historical.


Jon Garvey - #24746

August 6th 2010

@Daniel Mann - #24744

Quite right. Both types of interpretation are hard, and integrating the two more so.  But in both cases small datasets make for reasonable hypotheses but dubious conclusions.

For example, pinning a concrete eschatology (a literal millennium) on one part of one chapter of an apocalyptic-genre book has always seemed to me to be precarious (especially when one dismisses other views as heresy), whereas, say, the Messiah as God’s ultimate salvation plan is attested throughout the Bible.

Similarly, dating the earth by rates of sedimentation alone made for a hypothesis to work from in Victorian times - now that has been broadly confirmed by radioactive dating, rates of tectonic shifts, astronomical data, etc etc it becomes perverse to deny it.


penman - #24747

August 6th 2010

Daniel Mann:

== the style of Genesis is somewhat different than that of Judges and contains more figurative language perhaps, but I don’t think that its figurativeness argues against its historicity==

I was only talking about Genesis 1, not the whole book.

==1.  The NT speaks strongly in favor of the fact that the recorded events took place!==

I was only talking about chapter 1. Show me a single NT reference to the world being created in six days.

==2.  Continuity: There are continuous linguistic and thematic elements linking the 1st several chapters with the Abel—Joseph narratives==

But I was only talking about Genesis 1.

==3.  The genealogies argue powerfully for historicity.==

Well, er, I was only talking about Genesis 1 (this is getting repetitive, repetitious, & saying the same thing over again)

==4.  No verses indicate that these accounts were not historical==

The STYLE of Genesis ONE does not remotely seem to me, or to many interpreters, to be flat prose-historical. Once you get into later chapters, especially ch.12 onward, you’re into a fairly prosaic narrative.


Daniel Mann - #24754

August 6th 2010

Jon,

You’re right about a lot of our eschatological musings. There is a high degree of uncertainty about many of them. But I would also include in this brew the question of dating the earth.

There are millions of possible measures – everything is decaying or moving according to certain rates or principles. (Take the movement of the Moon towards the Earth!) This lends itself to several interpretive problems:

1.  We might be merely selecting those measures that support our theory.

2.  The evolution establishment has access to a thousand times more research funds than creationists. (Do you know of any creationists in major universities?). This creates a horrible imbalance in terms of the “evidence” generated.


Daniel Mann - #24756

August 6th 2010

Penman,

As for the six days of creation as history: Exodus 20:11 “For in six days the LORD made the heavens and the earth, the sea, and all that is in them, but he rested on the seventh day. Therefore the LORD blessed the Sabbath day and made it holy.”

Also, I think that there is far more continuity between Gen.1 and the rest of the Book and the first 11 chapters and Gen.12 than you are allowing for.


penman - #24762

August 6th 2010

Daniel Mann:

==As for the six days of creation as history: Exodus 20:11 “For in six days the LORD made the heavens and the earth, the sea, and all that is in them, but he rested on the seventh day. Therefore the LORD blessed the Sabbath day and made it holy.” ==

I have no quarrel with the existence of the fourth commandment! What I asked for was a single NEW Testament reference to the world being created in six days. I asked because your previous point was “The NT speaks strongly in favor of the fact that the recorded events took place!” Well, the NT speaks precisely nothing about God taking six days to make the world. If this was really as important an issue as young earthers claim, I find it distressingly weird that you can’t find Jesus or Paul or anyone teaching it in the scriptures of the New Covenant. Maybe, just maybe, it isn’t quite so important…?

I’ll have limited access to the internet for the next two weeks: away on a travelling holiday, & my technology is too primitive to have mobile internet access.

Thanks for a civilised & courteous discussion!


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