Methinks it is sort-of like two weasels

Certainly, and the number of non-selectable steps is what is of interest here.

I refer you to Darwin’s Black Box, where Behe outlines in detail why they are improbable. The essence of the argument is irreducible complexity, where the structure doesn’t work if one part is removed, thus a large number of non-selectable steps would be needed for these to evolve.

And you can move the starting time back to get to the existing variation, as non-selectable steps, and neutral evolution would also be non-selectable steps, making the transition exponentially more difficult.

Yes, it does mean what I am using it to mean, if the probabilities of various events are independent, then their joint probability is just the multiplication of all these probabilities, and this is exponential. If the probability of each event is .1, then the joint probability of n such events is .1^n.

By this kind of reasoning you in particular shouldn’t exist, as it is incomprehensibly unlikely that of all possible combinations of mutations that happened to result ten generations back in time, it’s you in particular we ended up with.

Just compound the probability the particular set of the roughly 100 mutations you were born with, with the probability of the 100 mutations each of your parents were born with, and so on. And 10 generations back in time your genome in particular looks so vanishingly unlikely the numbers are something like 1 times 10 to the negative ten millionth power.

And yet this is exactly the reasoning you’re providing to say evolution couldn’t happen. A textbook example of the Texas sharpshooter fallacy.


But this is known to be straightforwardly false, as many parts can be removed and rather than function as a flagellum(a propulsion system), the system functions as a protein translocation system instead.


I refer you to the primary scientific literature, which does not support Behe’s claims.

No, in scientific terms, Behe’s hypothesis, which he refuses to test empirically, is that IC structures cannot evolve.

Your conclusion doesn’t follow from your premise, as even pure Darwinian evolution is expected to produce IC structures.

You’re again denying the existence of neutral evolution. Why? Because Behe doesn’t mention it?

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But this is confusing the probability of an event viewed before the fact, with the probability of an event after the fact. Roll a die, what’s the probability that you get a 6? 1/6 before you roll, and either 1 or 0 afterwards.

It’s not so simple! “The outer membrane (OM) ring structures are not related between the two systems. While flagella include a P-ring spanning the peptidoglycan layer and an L-ring transversing the OM, injectisomes contain a secretin-type ring, probably acquired from various sources later in evolution [38], that spans both of these layers.” (NIH paper here)

Thus the injectisome is not simply a reduction of the flagellum.

I suggest you try reading the rest of that post. It will answer the rest of your comments here.

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That looks like word salad to me. You’re not understanding the point of existing variation, and you’re still misusing “exponentially.”

Tell me–why is extinction much more likely in an inbred population? What have they lost?

Your explanation tells me that you don’t know what it means.

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There are bacteria right now living with reduced flagella that function as protein translocases. If you think about it, the flagellum must necessarily consist in part of a system that functions as a protein translocase, because it is required to translocate the proteins that make up, for example, the hook and filament into the extracellular environment. So it really is that simple. The flagellum has a fully functional protein translocase as part of it’s structure, that literally has to be able to function in order for the flagellum to be able to be constructed. Thus the flagellum can in fact be reduced to a protein translocase, and there are species of bacteria known where that is it’s function.

Here’s an article:

Nothing about my argument requries that any extant injectisome is ancestral to extant flagella. You made an in principle argument from irreducible complexity that flagella couldn’t have evolved because, you said, removing a component would render it nonfunctional. And that is just wrong.


Yes but you’re the one applying this reasoning to things that now exist, after the fact of their origin, as if to show they couldn’t have evolved. Kind of an own goal that one it seems to me.


To briefly introduce myself I’ll say that I’m a layman who has followed the controversy for some time, on the scientific side. I do have some mathematical background and questions around probability are of interest - even if my knowledge of statistics is very, very rusty.

I think that I should point out that Behe does not explain that in Darwin’s Black Box. He admits that irreducibly complex systems could evolve by what he calls “indirect” routes, and asserts that these are improbable. However, he does not explain why they are improbable.

I’d add that the issue of unselected steps is one of the cases where past probabilities really can’t be treated the same as future probabilities. Unselected steps will occur and evolutionary change will certainly end up including some of them.


As biology goes, it’s pretty simple.

None of that supports your position. Also, the paper is from a British journal, not the NIH. Why did you call it an “NIH paper”? Did you read it, or just scan it for text to copy and paste?

They have a common ancestor. And functionally, the flagellum remains an injectisome, as its extracellular proteins are extruded during assembly.


Nonsense. ID does not define any cause, much less direct cause. Raspberry vinaigrette.


Well, bring the points to bear here, you may guess that I disagree with them. But I agree with this: “This is an event that is close to the edge of evolution, meaning that more complex events of this type are beyond the edge of evolution and cannot occur naturally.” (Larry Moran)

Well, how so?

They’ve lost variation.

Welcome Paul!

Well, where that possibly is its function, states the paper. But even if there is one selectable step on the way to a flagellum, that doesn’t discount all the unselected steps that would undoubtably be needed to get there. The question is the probability of the flagellum evolving, and it seems remote.

Only iff you assume evolution did it! Now some cause was at work, but to assume evolution did it, and then to conclude evolution did it, is to argue in a circle.