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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nedbrek - #24047

July 30th 2010

Marshall, we do have different definitions.  I think definitions can influence thinking.  How else do we come to different conclusions?

What has convinced you of an old earth?


Mike Gene - #24075

July 30th 2010

Hi Daniel,

You write:

While we both look at the physical world and can say, “God’s design is wonderful,” many sinfully attribute what they see to unintelligent (non-ID) processes (Rom.1). ID performs a needed (and loving) wake-up call saying, “You need to take another look. Mindless processes are incapable of explaining what you see around you!”

ID encourages us to take a second look at what we should already should know from the physical world, and asks us to reconsider our reductionistic and dismissive theories.

When I read Rom 1:20, it speaks about all of creation as a whole.  Yet ID, in order to “detect design,” takes a reductionistic approach, distinguishing one aspect of creation from another.  A popular argument compares Mt. Rushmore to other mountains, and in order to make the ID point, the mountains are put into the category of something “mindless processes” are capable of explaining.  According to ID, “mindless processes” are adequate to explain mountains, clouds, rain, rivers, seas, salt, wind, tides, etc.


Daniel Mann - #24076

July 30th 2010

Conrad,

I pray God will bless you efforts. If you have other verses, I’d be glad to see them.


penman - #24080

July 30th 2010

Daniel Mann:
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On the other hand, where does Romans 1 speak about design or a designer, let alone an argument that “here is design, which implies a designer”?

The attributes of God mentioned are “eternal power” & “divine nature” (or “Godhead”), v.20. The first seems to describe human consciousness of a fragile, contingent universe depending on a transcendent power. The second, as far as I see, corresponds with Calvin’s “sense of divinity”. Neither of these is an argument, I think, but a sort of immediate intuitive awareness, implanted in everyone (not just the few capable of following irreducible complexity arguments).

In v.32 Paul also speaks of moral awareness, but that isn’t an argument either, it’s once again something more immediate.


Daniel Mann - #24083

July 30th 2010

Mike,

In line with Nedbrek, I certainly wouldn’t call the creation of mountains mindless. Instead, I’d distinguish formulaic causation from direct unmediated causation.

More importantly, you insist that Romans 1 “speaks about all of creation as a whole.  Yet ID, in order to “detect design,” takes a reductionistic approach, distinguishing one aspect of creation from another.”

Certainly, perceiving the glory of God, according to Romans 1, doesn’t require that we take in His entire creation in one glance. We are limited creatures and this imposes limitations on the way we see things.

Contrary to the distinction you make, Psalm 19 states that the “Heavens declare the glory of God.” This verse doesn’t require us to perceive the heavens along with biology and zoology in one glance in order to see God’s glory. We can and must look at it in piece-meal fashion.

(You don’t seem to be a fan of ID.)


Daniel Mann - #24086

July 30th 2010

Penman,

I do agree with you that Romans 1 depends upon an inner intuitive awareness, but you can’t limit it to that. Romans 1 states that this knowledge of God is also based upon observation (“clearly seen”) and cognitive understanding (“understood from what has been made”).

You’re right that Romans 1 points to God’s moral nature, but implicit to His nature is His existence and the orderly and intelligent way that He created things to reveal His truths. It’s not an either-or thing! How could we possibly perceive His glory or His purpose by merely perceiving chaos? It’s His glorious design that communicates.

How can we perceive the greatness of Tolstoy or Dickens if their novels consisted of a random assortment of letters? Rather, it’s because these letters are Designed in such a way as to form a coherent and meaningful picture that we can appreciate these novels. Any communication of truth depends upon order and ID. How then could a world lacking ID reflect anything about God? Why fight it!


conrad - #24088

July 30th 2010

Dan ,...the whole of Day 4 scoops the final conclusion that NASA’s Apollo program gained. They wanted to learn how the moon formed AND THEY DID.

The moon formed late and in a manner that gave us all the seasons ,years ,months and other time and navigation measurements.

The three previous theories would not have fulfilled the Bible’s description of simultaneity in the events leading to the establishment of the length of these primitive time units.

An entirely new theory, the Giant Impact theory, was introduced and PROVEN,...AND IT DID AGREE PERFECTLY WITH THE SCRIPTURE.

The earth got it’s tilt, it’s rate of rotation and the moon all at the same time,... plus a new lighter atmosphere allowing sun and stars to become visible in the sky.

The new tilted earth also had seasons and years for the first time of course.

Get “The Big Splat” by Dana McKenzie.
That whole event was pre-announced in Genesis in the description of Day Four.


penman - #24094

July 30th 2010

Daniel Mann:

I’m not sure I’m fighting ID. Depends what it means. If it means that God (who is intelligent) designed the universe (gave it all its properties, laws, processes), I presume any theist believes in ID.

But some seem to use the phrase differently. Something like, “Here are aspects of the universe which could not have come into being by the natural or normal processes science investigates. In biology especially, here is a structure so complex, it could not have emerged by any gradual or incremental process open to scientific explanation. Therefore we are dealing with a phenomenon here that must be the product of intervention in nature by some kind of transcendent power.”

Well, this may or may not be true; I’m agnostic on it; but I don’t see why a theist MUST embrace that version of ID.

Stepping back, if we ascribe design to the universe as a whole, what do we mean? If we mean “all its properties, laws, processes were given by God”, we’re merely restating our theism.

If we mean, “the universe makes sense only as an intelligent contrivance of means to ends”, I’m not sure that’s true. There, I invoke Newman: “I believe in design because I believe in God, not in God because I see evidence of design.”


conrad - #24101

July 30th 2010

Yeah Penman I see your point.

  It boils down to asking “can this problem be fixed on line,... or does a service geek have to come out and actually make a call to fix it.?”

I don’t think God put on the snorkel mask and got into the water to fix the flagella motors.


Daniel Mann - #24105

July 30th 2010

Penman,

I tried to argue that Biblically, ID as evidence for God is imperative (I understand the distinction you are making!). But I also think it imperative observationally and scientifically.

I think that we can and always do clearly distinguish between intelligent causation – writing books, poetry, music, architecture – and formulaic, predictable causation. Forces only do one thing and do it predictably. Gravity attracts. It can’t scramble my eggs or write me a sonnet. Some phenomena can be explained by this latter understanding and some can’t. If I find a new gallon of milk in my frig, I know that the movement of subatomic particles—however mysterious – can’t account for it. However, ID – namely my wife – can!

Of course, you might argue in favor of sub-atomic particles, claiming that we don‘t understand enough about them to dismiss the possibility that they might be responsible for that new gallon of milk. Granted, but I think wisdom would direct us to form our conclusions based upon the limited facts that we do have.

Besides, if you acknowledge that God kicked everything off and that He answers prayers, why would you dismiss Him from the business of creating species?


Marshall - #24111

July 30th 2010

Hi Daniel, you asked:

Besides, if you acknowledge that God kicked everything off and that He answers prayers, why would you dismiss Him from the business of creating species?

For some of us, God is not dismissed from the aspects of nature that work according to regular processes (whether those processes are just the way God chooses to regularly work or real entities God created is beside the point). This is why I believe God provides my daily bread, even though I know some of the natural processes involved in that. I believe God formed me (not just my distant ancestor), and the fact that scientists have learned how some of that formation takes place does not remove God from the process. I even believe that God sends lightning and rain and provides food for the hungry lion! Theories of mitosis, electromagnetism and evolution do not diminish this.

For me, God is not dismissed from any of these natural processes. I do not limit God’s activity to things we don’t understand (though of course there is much God does that I don’t understand). As a result, advances in science increase my awe of God’s handiwork, rather than cutting off more and more things from God’s domain.


Daniel Mann - #24124

July 30th 2010

Marshall,

Alas, I think I understand your position better. However, familiarity does not always breed acceptance.

It seems that in a practical sense, your theory is inseparable from naturalism with the exception the you believe that God is actively involved in “natural” undirected processes.

I don’t know if you are very concerned about this, but I think that your formulation fails the Biblical test in a number of ways. Nor can it explain those phenomena that naturalism fails to explain. While you might explain the fine-tuning of the universe and the first life as an IDer might, you probably would resort to “natural” processes to explain later developments?? – freewill, speciezation, consciousness…?


T Millar - #24132

July 30th 2010

The illustration of the designed landscape is really poor. It would be better used as an illustration of how something that was designed could actually look as if it had evolved from something else, and even then its not even worth using. But I mean, come on,using something that has been designed and looks natural to show how something that looks designed could have arisen naturally is like arranging some car parts to look like a car engine and then saying there you go - that car engine is not real….........but the fake WAS STILL DESIGNED!


Jon Garvey - #24160

July 31st 2010

@Daniel Mann - #24124

“Your formulation fails the Biblical test…” On the contrary, Marshall’s position seems to reflect the Biblical worldview rather accurately. There is no distinction between the natural and supernatural in Scripture - all things are attributed to God. Maybe the most dramatic example is the Lord’s statement that not one sparrow falls to the ground apart from the Father’s will.

Although the point of the saying is that he cares for his own even more (“the hairs of your head are nimbered”) it is clear that every day thousands of sparrows die from cats, parasites, kids with airguns and every kind of natural cause. It is doubtful if it would be proper to regard many of those deaths as “miraculous”. In the same way his special care for believers consists not only in miraculous interventions, but in governance over everything that might damage a hair of my head, from natural baldness to falling sparrows - that is every natural, or even random, event. (...)


Jon Garvey - #24161

July 31st 2010

Incidentally why would not “leviathan” equally apply to contemporary reptiles like crocodiles as to dinosaurs? The only thing in the Bible that would suggest it was something stranger is the description in Job, which mentions it breathes fire - if you take that literally it would have to be a dragon, not a dinosaur.


Daniel Mann - #24163

July 31st 2010

Jon,

I agree with you that the Bible doesn’t distinguish between natural and unnatural. God governs, as you say, by the miraculous and by laws. You too apply this to today’s situation.

Therefore, I wouldn’t dismiss the idea of God working miraculously (ID) in the creation of the species.


Jon Garvey - #24169

July 31st 2010

Daniel

The problem surely is that when ID points to a process and says, “That bit’s miraculous”
(a) somebody comes along and says, “Here’s the evidence it isn’t” (as has happened re Behe’s work already) and
(b) It goes beyond Scripture in saying that life arises partly miraculously - Scripture just says it’s God’s work, which would allow for it being miraculous, or natural (rather “providential” in the terms we’ve been discussing), but gives no suggestion that it’s a mixture of both.


Mike Gene - #24170

July 31st 2010

Daniel,

In line with Nedbrek, I certainly wouldn’t call the creation of mountains mindless. Instead, I’d distinguish formulaic causation from direct unmediated causation.

When it comes to mountains, can their origin be explained in terms of chance and natural law?  Or is there something about them that would compel us to invoke an intelligent cause? 

More importantly, you insist that Romans 1 “speaks about all of creation as a whole.  Yet ID, in order to “detect design,” takes a reductionistic approach, distinguishing one aspect of creation from another.”

Certainly, perceiving the glory of God, according to Romans 1, doesn’t require that we take in His entire creation in one glance. We are limited creatures and this imposes limitations on the way we see things.

I did not insist on this.  I explained that is how I interpreted this passage.


Mike Gene - #24171

July 31st 2010

Yes, we are limited and that, I believe, is one of the themes of that passage.  That is, anyone who has ever camped far from the reach of modern day human technology could “take it all in” one night, experiencing the majesty and beauty of all creation, which testifies to the divine power of God.  Contrast this to looking at pictures of bacterial flagella.  It looks like something a human or alien could make. 

Contrary to the distinction you make, Psalm 19 states that the “Heavens declare the glory of God.” This verse doesn’t require us to perceive the heavens along with biology and zoology in one glance in order to see God’s glory. We can and must look at it in piece-meal fashion.

Yes, the heavens declaring the glory of God is not the same as microbes declaring the glory of God.  I think the psalmist is saying that anyone experiencing the starry sky is experiencing something that declares the glory of God.  I don’t think he is saying that if we study astronomy books, the glory of God will be declared.


Mike Gene - #24172

July 31st 2010

(You don’t seem to be a fan of ID.)

Let me ask you a simple question, Daniel.  What if ID is wrong?  What if Richard Dawkins’ explanation of evolution and life’s origin is not only true, but is all there is to evolution?


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