The Flagellum is Not a Motor?


(Timothy Horton) #252

(facepalm) Yes Mung, that’s exactly what he and the rest of the ID crowd are arguing.

(Dan Eastwood) #253

So many flags, maybe it’s time to close this thread.

(S. Joshua Swamidass) #254

I think it needs to be split into a “comments on” thread and a main thread. There is actually much to discus on the OP, and @Michael_Callen actually took me up on actually trying to list similarities and differences, which was the original request. That is where the action is.

(Herculean Skeptic) #255

Agreed. There are actually some interesting discussions that aren’t related to semantics.

Personally, I don’t believe that the “motor” is a motor. (I’m purposely leaving out “rotary” because I still don’t understand how that fits in.) I think that a motor is a metal appliance manufactured by a human. I think that a bacterial flagellum is an incredible biological machine. I think that there are a lot of smart people who think that it evolved, and I can also see why people are incredulous at the thought that such a thing assembled itself (I know that is technically incorrect to say.) I think that it is an interesting topic to explore. But I agree completely with Joshua and the other evolutionists here that calling it a motor, doesn’t mean that it was designed.

My honest opinion is that I’d love to see the topic explored. The problem is that people use analogy (it’s a motor and therefore is designed, ergo designer) or the theory of irreducible complexity as evidence for intelligent design. Unless it can be demonstrated (experimentally) that there is no possible way that the flagellum could evolve, I don’t see how the issue can be solved. To claim that it was intelligently designed will continue to be answered with, “prove it!”

I don’t object to a discussion, but it needs to be over how, experimentally, the issue could be solved. Otherwise, it’s going to continue on the same, worthless, depressing path it is on now. IMHO.

I respect you for asking this question, but I don’t think that it is important in this discussion. If a bacterial flagellum is a motor, what then? If it is not a motor, what then?

@Mung @gbrooks9 I really don’t think you two are understanding one another… or you’ve fallen into a gross misunderstanding. I don’t believe that your two viewpoints are that far off from one another. George, I missed, also, where you understood Mung to be taking shots at you. I’m not trying to dig up junk, but I was curious. Maybe PM me the link?

(S. Joshua Swamidass) #256

I agree. It is pretty amazing. You know, however, that the bacterial flagella does not use ATP, right? Also, the eukaryotic flagella uses ATP but does not rotate.

Either way, it is pretty amazing :smile:.


But that is a straw-man. No one is arguing that because it is a motor that it follows that it was designed. Brian certainly did not make that claim.

That’s an incredibly narrow definition of a motor and rather begs the question. I don’t think the ID critics ought to be allowed to beg the question. Did you note that your definition of a motor fails to even mention its function at all?

That’s an impossible challenge and relies on an argument from ignorance. It’s also shifting the burden of proof. Those who claim that the flagellum evolved and claim to have a theory that explains the mechanism by which it evolved have the burden.

Then it is not the case that motors are metallic devices manufactured by humans.

And it seems very important to @swamidass that what everyone else calls a motor in the literature isn’t actually a motor. So if it is motor it removes yet another objection to ID.

If someone is going to argue that ‘x’ is not a motor, shouldn’t they define what a motor is, as you have done? Especially if they are setting out to correct another scientist. And even more so if they are not an expert in motors.

(John Harshman) #258

For once, Mung is making sense here. What does “The Flagella [sic] is Not a Motor” mean? If it just means that it isn’t made of metal, that’s a pointless subject. What is the crucial definitional feature of a motor that the bacterial flagellum lacks? What does @swamidass mean by his statement that it isn’t a motor? What did the various creationists mean by their statements that it is? I can’t answer any of those questions, and yet they seem crucial to the subject.

(S. Joshua Swamidass) #260

I just mean that it is a motor in some sense, but not in others. I’ll change the topic of the thread into a question if it helps. As I repeated ad nauseum:

There are many ways a flagellum is like a human-designed motor, and many ways it is not the same. We have to have a very good grasp of what the similarities and dissimilarities are to reason about flagellum in this way. That is my only large point. The smaller and interesting pieces of this is:

(Paul A Nelson) #261

Josh, PLEASE change the erroneous title of this thread. Every time I come to this site, this solecism bugs me. “Flagella” is the plural of “flagellum.” The title should read “The flagellum is not a motor.”

Let’s do our tiny part to beat back the tide of linguistic barbarism.

(S. Joshua Swamidass) #262

Noted. Sorry for assaulting everyone sense of grammar. I promise the assault is far more comprehensive in the first draft of my book. You are all being spared from this at the moment.

(Timothy Horton) #263

Now if only everyone would do their part to beat back the tide of Creationist scientific illiteracy.

(Dale Cutler) #264

I’m curious about the speeds involved with ATP- or enzyme-mediated conformational changes vs. the speed of the proton mechanism. Might it be that the proton effect is what allows such rotational speed?

(Herculean Skeptic) #265

Really, I see it all the time. It happens here all of the time. This is the reason I was hoping to split the conversation into two aspects and not conflate them. 1) Is it okay to refer to the bacterial flagellum as the bacterial flagellar motor, and, 2) was it designed or did it evolve. The root issue regarding using the word “motor” in the name was that people were co-opting it and inferring that motor = design = designer.

Sorry, I did not mean for that to be the complete definition of a motor. I was actually juxtaposing what I believed to be the universal understanding of what a motor was against what had been proposed earlier (I cannot find the quote now), which said that a motor could be a biological product. I was merely saying that in using the label “motor”, one is applying an analogy such that the function of the standard electric motor is similar to that of the bacterial flagellum. I’ve been pretty consistent throughout in stating that I was referring specifically to the function of the motor being that which was in common with the flagellum.

So then, what is the discussion over? What is the purpose? One side demands that its ability to evolve be proved, and the other side says it has been already. One side says that the flagellum couldn’t have evolved because it is irreducibly complex, and the other side says that it is not so. I don’t understand why an impossible, nevery-ending discussion is so important to have, then.

We just end up with non-stop streams of this:

Please (anyone) help me to understand (I sincerely want to know) why we should even begin the discussion if it is utterly hopeless, as it seems? I don’t want to enjoy this special bit of hell refereeing a bout like this with an infinite number of rounds and no conclusion. Is the solution to agree to disagree? To say that one side believes that it evolved and the other side believes that it was designed, and just leave it at that?


There doesn’t seem to be any solid consensus models out there. If you want a super technical paper on the various models, you might want to read this paper:

The author of that paper suggests that the incoming ion “cocks” the proteins in the stator, and when the ion moves off of the protein it uncocks and moves the rotor. Therefore, the speed (or perhaps torque is a better term) is determined by the “springs” in the stator proteins. In other words, the speed is determined by the intramolecular forces between different parts of the stator proteins.

Of course, my standard “if I am understanding the paper correctly” addendum applies.

(Dale Cutler) #267

Thanks! I’ll see if I’m capable enough to wade through it. :slightly_smiling_face: (I won’t be doing freestyle. :grin:)

(Timothy Horton) #268

That would be fine if the ID-Creationist side didn’t continually use such sleazy tactics to try and foist off its anti-science horseshit on an unsuspecting lay public. But sadly they do so they must be countered.

(Herculean Skeptic) #269

Okay, so let’s talk about that for a second. You are saying that you are not willing to say that you believe that, for instance, the bacterial flagellum has evolved, and allow someone from the ID camp to say that they believe that it was intelligently designed, and leave it at that, … because in their literature they use “sleazy tactics” and other “horseshit” and must be countered? Just want to be clear.


Some topics have more baggage than others. Why is the Scope’s Monkey Trial so famous? Why did a group of people build a massive and insanely expensive non-functional ark in the middle of Kentucky, chocked full of anti-science rhetoric? For better or worse, the friction between the evolutionary sciences and religion is a touchstone in our culture.

(Herculean Skeptic) #273

Very nice!!!

Clearly!! I absolutely agree. Though there was a noteworthy volume of irony in that statement. Arguably, one could counter horseshit in a variety of ways. There’s the high-road approach for instance. Also, there’s the follow the leader approach. Do what Michael Behe does, but say what you want to say, instead, that is, of complaining about how the other side successfully educates people (correctly or incorrectly), educate them yourselves.


HT: T_aquaticus

The bacterial flagellar motor couples ion flow to rotary motion at high speed and with apparently fixed stoichiometry. The functional properties of the motor are quite well understood, but its molecular mechanism remains unknown. Recent studies of motor physiology, coupled with mutational and biochemical studies of the components, put significant constraints on the mechanism. Rotation is probably driven by conformational changes in membrane–protein complexes that form the stator. These conformational changes occur as protons move on and off a critical Asp residue in the stator protein MotB, and the resulting forces are applied to the rotor protein FliG.

Bacterial flagella are helical propellers turned by rotary motors in the cell membrane

Are these scientists intentionally misleading other scientists when they call them rotary motors (given that they are not actually motors) and when they likewise refer to mechanisms (given that there are no mechanisms in the cell)?