t f p g+ YouTube icon

Bacterial Flagellum: Appearances Can be Deceiving

Bookmark and Share

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.

Next post in series >

Learn More


View the archived discussion of this post

This article is now closed for new comments. The archived comments are shown below.

Loading...
Page 4 of 8   « 1 2 3 4 5 6 7 »
Daniel Mann - #24225

August 1st 2010

Mike,

Although Psalm 19 declares that we can see the glory of God with the unadied eye, why would you discount that this Psalm also would imply that we can detect His glory through the lens of the telescope?


Daniel Mann - #24226

August 1st 2010

Jon,

I think you are harkening back to the “God of the Gaps” critique—that the ID case depends upon gaps that still exist in the explanations of naturalism.

However, I think that the critique of “Naturalism of the Gaps” is far more powerful. Naturalism is assumed merely because we can’t see the hand of God. However, there is not one stitch of evidence, scientific or otherwise, for naturalism—that the laws and forces are natural, unintelligent, and self-sustaining. While we all agree that phenomena occur formulaically and predictably, it makes far more sense that the laws are supernatural—originating and sustained by the mind of God.

Please see this link: http://mannsword.blogspot.com/2010/02/skeptical-about-atheism.html


beaglelady - #24227

August 1st 2010

However, there is not one stitch of evidence, scientific or otherwise, for naturalism—that the laws and forces are natural, unintelligent, and self-sustaining.

So there is then no nature, and nothing natural?  If that is so, what would supernatural mean?


Scanman - #24230

August 2nd 2010

As a Theistic Evolutionist who believes that God controls the environmental pressures that guide evolution, I see no problem combining Intelligent Design with TE.

It is a Deistic viewpoint that attributes God with a ‘hands off’’ approach to evolution.

Peace


Mike Gene - #24231

August 2nd 2010

Daniel,

Although Psalm 19 declares that we can see the glory of God with the unadied eye, why would you discount that this Psalm also would imply that we can detect His glory through the lens of the telescope?

I’m not discounting that.  I’m just saying that I sense or see nothing that leads me to think that passage is saying we should be able to detect His glory through the lens of the telescope.  I think the passage is appealing to a universal experience among all people.  An experience that would not depend on one having expertise and technology.


Mike Gene - #24232

August 2nd 2010

HI Scanman,

As a Theistic Evolutionist who believes that God controls the environmental pressures that guide evolution, I see no problem combining Intelligent Design with TE.

Interesting.  One thing to ponder is that “environmental pressures” tend to largely be the output of other living things.  For example, bacteria and viruses are ubiquitous and constitute a major component of our “environment.”  Evolution has occurred in the context of a biosphere and not on the surface of a sterile planet.


penman - #24235

August 2nd 2010

Daniel Mann:

<

>

In the realm of secondary created causes, we make this distinction. Some created causes are intelligent, some not. An intelligent created cause produced Shakespeare’s plays. A non-intelligent created cause produced an asteroid crater.

But how do we apply this to the relationship between God (the Primary Uncreated Cause) & the created realm? God is an intelligent cause, & He is at work in all the aspects of the cosmos that we ascribe to secondary, created, non-intelligent causes. Eg the asteroid crater. It’d be very Biblical to say of the crater “God did it” - the Bible sees secondary, created, non-intelligent causation in the light of God’s sovereignty.

HOW God’s sovereignty relates to secondary, created causality, the Bible never explains (as far as I know). It’s a metaphysical issue science can’t resolve.

But if God is somehow at work even in non-intelligent second causes, then I don’t think we can distinguish different parts of the cosmos into “non-intelligent cause” (God not involved) & “intelligent cause” (God involved).


Daniel Mann - #24236

August 2nd 2010

MIke,

I certainly agree with you. Therefore, I don’t think we can conclude that any of these verses PRECLUDE a more systematized or scientific appreciation of God’s creation. When ID says, “Look at the incredible interrelationship of the heavens,” it’s no more outside of the scope of Psalm 19 than an ancient Israelite saying, “look at the heavens from this mountain. The stars are even more glorious up here!”


Daniel Mann - #24237

August 2nd 2010

BL,

You questioned, “So there is then no nature, and nothing natural?  If that is so, what would supernatural mean?”

Naturalism has so thoroughly co-opted science and blinded our minds that the suggestion that there is no evidence whatsoever that things run by natural and not supernatural laws seems totally off-the-wall. I think that we need to re-examine this presupposition, asking “where’s the evidence for this assumption?”


Daniel Mann - #24238

August 2nd 2010

Penman,

I think that the question you are raising is this, “OK, we agree that God is behind direct causation and indirect (through laws) causation. Therefore, why couldn’t God create through evolution?” (Please excuse me if I’ve missed your intent!) Here are my problems with this:

1.  It violates Biblical revelation.
2.  It violates evolution that posits NATURAL selection and RANDOM mutation.
3.  It violates what we know about direct and indirect causation (laws of physics), which is very limited in what it can do. Forces and laws only do one thing. They work only according to formula, never generating new coherent information, but instead work from the information or formula already inherent within them.


beaglelady - #24281

August 2nd 2010

Daniel,

The objective reality of nature is the evidence for the natural world.  I’m not saying that nature is all there is.  I’m just saying that there is a natural realm.  God transcends the natural world.


penman - #24288

August 2nd 2010

Daniel Mann:

Your 3 points are all discussion-worthy!

What I was trying to say - maybe not very brilliantly - is that I don’t like distinguishing between different aspects of the cosmos in relation to God as “intelligently caused” & “not intelligently caused”. I affirm the sovereignty of an intelligent God in every aspect of the cosmos. Biblically I have in mind texts like “the purpose of Him who works all thinga according to the counsel of His own will” (Eph.1:11). The fall of an individual sparrow (Matt.10:29) is as much within the sovereign jurisdiction of God’s intelligence as the most complex molecular structure. Ultimately everything has intelligence behind it, even if we think it random or badly designed (the finitude of our intellects should guard us from undue metaphysical claims in the absence of revelation).

However, back to the 3 points: yes, I think God created through evolution (common descent with modification over deep time, with natural selection as a basic mechanism). You think not, because “it violates Biblical revelation”. I don’t think so, since I don’t think the Bible says anything about HOW God created (or nothing that counts as scientific description). Why do you think it violates the Bible?


Daniel Mann - #24295

August 2nd 2010

BeagleLady,

You state, that “The objective reality of nature is the evidence for the natural world.”

You are assuming the very thing that I am asking you to provide evidence for—the “natural world.” Is it indeed natural, unintelligent and without plan, or do the underlying laws and forces emanate from the mind of God? Are the laws all independent and free-standing or do they find their harmony, uniformity and sustenance from God? Is this idea of “natural” just another reality we’ve constructed with our own minds.

More importantly, is it a religion of man foisted upon the science classroom to illegitimately exclude God?


Daniel Mann - #24298

August 2nd 2010

Penman,

OK, let’s set aside the question of whether or not the Bible is giving scientific descriptions and just regard whether it is giving historical descriptions. Here are some ways that I see that evolution conflicts with the Bible:

1.  Each species was created after its own kind (Gen 1:21, 24, 25), not gradually out of the predecessor.

2.  God did not create man from pre-human creatures (1:27)

3.  Originally, everything was “very good” (31). All had been herbivores (31). Thus, no survival of the fittest.

4.  Jesus and the writers of the NT affirm the historicity of the Genesis accounts (Mat 19:4-6).

5.  Sin and death entered through Adam and Eve and not because of a fault in God’s original design (Gen 3; Romans 5:12-19). Jesus came to correct the mess made by man (1 Cor. 15:21-22), not the mess created by God.

6.  The “restoration” (Acts 3:21; Rev 21-22) will not be to the original “dog-eat-dog” mess, but to what had been “very good.”

7.  The several genealogies argue for Genesis as history, not fable.


penman - #24306

August 2nd 2010

Daniel Mann:

Oh dear, you’ve swamped me. I don’t have time to give thoughtful responses to all your seven points,certainly not within BioLogos word limits.

You’ll have to be content with point 1. The “according to their kinds” language of Gen.1 just means, in English idiom, that God created all kinds of animals. It doesn’t say that each specific animal REPRODUCES according to its kind (i.e. fixity of species), merely that God created various kinds of animal. It doesn’t tell us how He did that. The biological mechanics are not described.

Besides, who believes in fixity of species these days? Young earth creationists now concede that animals can evolve within pretty wide margins, so that they aren’t reproducing carbon copies through all generations. You end up having to define kind extremely broadly in order to insist that one kind has never developed into another kind.

Trying to base a scientific biology on the “kinds” language of Gen.1 is misguided. I don’t think Moses (or whoever wrote or redacted Genesis) was thinking scientifically when he spoke of kinds. I think he just meant “kind” in a common sense, look & see way - all sorts of creatures.

Maybe someone else can answer the other points - I’m out of words!


Trevor K. - #24394

August 3rd 2010

Unfortunately I don’t have the time to read to all the comments to see if this has been addressed:
Kathryn’s logic or reasoning has a flaw in it: On the one hand she’s telling us about the bacterial flagellum and it’s construct which appears to have been designed by some person. Then she jumps to a sketch/painting constructed by an artist to show that appearances can be deceiving, using this as a basis to infer that the flagellum could have been “evolved”.

I think the problem with using these examples in this fashion is that the sketch by the artist is documented, verifiable and repeatable. We can certainly go back to him and have him show us how it’s done and in fact we can do it ourselves[with some practise and variation].

On the other hand, the bacterial flagellum exists as it is without any one of us having the faintest clue as to how it got to be that way. It’s not documented anywhere so we cannot verify it or see that the construct is repeatable by an outside agent[us].
Hence to make the leap and say that it evolved is not a true statement. One can certainly speculate that that is how it got to be that way but it simply remains speculation. It’s equally valid to say God designed it and built it as is.


Daniel Mann - #24406

August 3rd 2010

Penman,

Thanks for grappling with the Biblical evidence. I think you’re right that “after own kind doesn’t imply a rigid “fixity of species”—there seems to have been a lot of genetic diversity built into each species—but Genesis does seem to imply that they do reproduce in this matter.

I think that if you pursue this inquiry further, you’ll find that Darwin and Jesus are irreconcilable.


Trevor K. - #24411

August 3rd 2010

Penman,

Besides, who believes in fixity of species these days? Young earth creationists now concede that animals can evolve within pretty wide margins, so that they aren’t reproducing carbon copies through all generations. You end up having to define kind extremely broadly in order to insist that one kind has never developed into another kind.

I think the difference here is that the information to diversify the way that they have is already built into their DNA by God.
Evolution on the other hand proposes that that information is newly created - something that goes against all knowledge of the DNA structure to date. The information to fashion raw materials to built, then to actually coordinate and guide the construction of new limbs, feathers and the like and then ultimately how to use such structures just cannot be plucked out of the air by evolutionary processes. Such just doesn’t show up on the radar. Here I’m talking about reptiles turning into birds, not to a colony of bacteria becoming drug resistant [some drug resistance already exists in the colony].


Jon Garvey - #24413

August 3rd 2010

@Daniel Mann - #24298

Daniel - taking your point (1) combined with (3b) one surely has a BIG problem.

Gen 1.30 doesn’t actually say all animals were herbivores - it says they were given every *green* plant (as opposed to seed-bearing plants and trees with fruit which were given to man, v29). That means not only that lions ate green plants, but so did dung-beetles, filter-feeding whales, chimpanzees, stinging jellyfish, spiders etc.

If that were the case, it would require a completely new and generalised re-creation after the fall, on which Scripture is completely silent, unless you consider that the ground being cursed and producing thorns and thistles for Adam can be stretched in a completely non-literal way to include lampreys losing their chewing teeth, moles growing shovels and moving underground where there are no green plants, insect larvae changing to fungi, angler fish no longer fishing for lettuce, millions of species developing camouflage ... you’re left with an animal kingdom that bears so little relationship to the original that you’ve abandoned one of the big reasons for opposing evolution anyway.

There are better ways of understanding the text more in keeping with what the author wanted to say.


Daniel Mann - #24416

August 3rd 2010

Jon,

I certainly can’t speak authoritatively about what happened at the Fall and the subsequent biological changes, like what happened to the serpent. Perhaps the DNA of the animal kingdom already contained post-Fall contingency plans?

However, if you look at the overall thrust of the Bible, there will be a return to purity and innocence, to a time when everything was “very good” – with some gracious modifications of course. As before, the lion will lay down with the lamb, according to the original state of things, when everything was “very good.” And the child will play with the adder.

All of this – and much more – demands that we understand the Garden as TRULY A PARADISE where there was no killing of animals. This is also a very important theological piece. If creation had been a bloody dog-eat-dog place from the get-go, then the fault of blood, death, sin and the survival of the fittest is not ours but God’s – bad theology! If God had enshrined the principle of survival-of-the-fittest, then how can he blame Adam for eating the fruit and wanting to become “fitter?” Or Cain for killing his unfit, naïve brother?

Instead, consistently the Bible lays the problems at our feet and the solution at God’s.


Page 4 of 8   « 1 2 3 4 5 6 7 »