Fish, Evolution, and Moving Goalposts

There is one question that my brain keeps coming back to: what kind of evidence do ID supporters want for the evolution of already existing adaptations?

This question came up again when I was reading the Discovery Institute’s article on the evolution of antifreeze proteins in fish:

So what exactly are ID supporters asking for when they ask for the evolutionary history of an adaptation? Far as I can tell, evolutionary histories are going to necessarily require changes in DNA sequences (e.g. gene duplications, rearrangements) and selection. As discussed in a different thread, each and every mutation that happens is extremely improbable and serendipitous, including those that we see happening in the lab as a normal course of reproduction.

If these mutations happened in living fish right in front of our eyes, would that be evidence for evolution? If that would be evidence for evolution, why are there different rules for mutations that happened in the past?

So we have to ask, what are ID proponents asking for when they ask how the bacterial flagellum evolved, or how the blood clotting cascade evolved? What do they expect to see in that evolutionary explanation if mutations and selection are not allowed as part of the explanation?


They deliberately ask questions which they know would take a working time machine to answer. It’s all for propaganda purposes so they can crow “See! science can’t answer therefore the Christian God DESIGNER is the answer!”.

ID isn’t a scientific position. Never was and never will be. It’s a religiously based political one.


Yes, they would be evidence of change. Perhaps even of genetic change. Maybe even of heritable change. IDists agree that change happens.

They are allowed. Because, supposedly, they are necessarily required.

You might be a Darwinist if you think like a Darwinist and if your explanations are Darwinian. :slight_smile:

Are you seriously proposing that selection is a necessary requirement?

And it’s not just mutations, it is mutations that are random with respect to fitness. And it’s hard to make sense of fitness absent the concepts of adaptation and selection.

Which is why Behe’s argument is a direct challenge to the scientific consensus and why he is not tilting at windmills.

But would it be evidence for evolution? Would it falsify intelligent design in the eyes of ID supporters?

Then why are these mechanisms described as “magic wands” and dismissed as viable explanations?

It is certainly one of the mechanisms that drives evolution, is it not?

Are you saying that ID supporters would accept these explanations if we included neutral drift?

But then the question becomes what kind of evidence they would not simply dismiss as one of these purported “just so stories”? That’s apparently the go-to reply when evolutionary biologists use phylogenetic inference to explain how some gene or adaptation evolved.

But how the hell else WOULD one explain the existence of some gene or adaptation that emerged in the past, but through predictive models consistent with patterns observed through comparative genetics?

What would evidence for past evolution then have to look like, to not just be dismissed as another “just so story”?

If gene X evolved from non coding DNA, what would evidence for that look like that ID proponents would not dismiss as a “just so story”?


And a related question, since ID proponents are fond of saying ID rests on “an inference to the best explanation”, how in the hell would ID account for some present adaptation or gene in a way that would not ALSO be a “just so story”?

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It makes a difference whether evolutionary biologists use phylogenetic inference to explain that some gene or adaptation evolved or whether evolutionary biologists use phylogenetic inference to explain how some gene or adaptation evolved.

ID arguments such as those put forth by Behe are not about “the that” but about “the how.”

So which are you talking about?

A weakness of ID, imo, is its failure to address the how question in a way consistent with what we know about how designs are actualized. I don’t think I’ve been shy about saying that. So I do think you pose a very good question.

This is one of my favorites:

Palm rushes towards face.

What in the world do they think a gene duplication would look like? I suppose a dog running across the beach would be a “just so story” or a “magic wand explanation” for these impressions found in the sand:


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The only argument Behe seems to have is that the mutations didn’t happen while we were watching. It boils down to a “Were you there?” type of argument.

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Yep, and in what way could an ID theory for the same event ever hope to not suffer the same problem?

ID Gene Creation Game Rule 1: Whenever you find sequence similarity between two genes, just invoke an intended photocopy event with designed additional substitutions of some hypothetical, ancient ancestral gene, and you can explain how two different genes came to share their similarities and differences.

How is this any less of a “just so story”?

ID is one HUGE just so story. Why did the designer create all the body plans in the Cambrian? Just because.


I agree with that, but I think the method used to give evidence for both is the basically the same. Have a predictive model, compare it to data. Some times the data available might not be good enough to explain how X evolved, but still good enough to infer that it evolved.

ID arguments such as those put forth by Behe are not about “the that” but about “the how.”

So which are you talking about?

In this instance I’m thinking of the recently published paper on the evolution of antifreeze proteins in polar fish, and the response it has gotten on webpages like Evolution News & Views. There this paper is basically just dismissed as one of these “just so” stories. That’s what spawned this thread by T_aquaticus.

I wonder what ID proponents who advance the “it’s nothing but a just so story”-dismissal would ever accept as good or sufficient evidence to show THAT or HOW some gene evolved. I wonder if they have even thought about it.

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You’re just an anonymous “critic.”

I am not sure it’s fair to call this one a just so story… but I am also not sure what is being described is evolution. Look at how Jerry coyne describes the process in his blog -

What’s remarkable about this configuration is that every bit of it, including the two proteins themselves and the promoter sequence, was cobbled together via translocations and duplications of DNA (this happens passively in the genome) until all the elements were in place. And the “functional” gene couldn’t function right up to the very end, when the promoter sequence moved to the right place to allow the protein-coding region to produce an RNA transcript. This entire series of steps was reconstructed by sequencing the DNA of relatives that don’t have functional AFGPs, so we could see the evolutionary order in which things were assembled, and where the functional bits originally came from.

He is describing a series several steps in a particular order which are supposed to have happened by accident without the help of even selection to give it any direction. He is essentially describing a miracle. Organisation without any reason or cause.

After these 6 events happen by “serendipity” or “Providence”, Jerry coyne claims the below-

Further, natural selection could now act on the functioning gene to make it more effective, simply by selecting for those genes that had even more duplications of the Thr-Ala-Ala segment, so we had a big protein of repeated units that could act as an antifreeze in fish blood (E—>F). (More repeats = better antifreeze protection.)

It’s a bit more complicated than this, but this is the essence of how the final protein came to be. And it’s not speculation, because all the bits can be found in other species or posited in ancestors, and so this reconstruction is fairly sound. Moreover, it involves processes known to operate in the DNA: the moving of bits around by translocation, duplication of sequences, etc. No divine intervention is required to do this, even though the protein isn’t functional until it’s put together with the secretory protein and the promoter.

On top for that the process needs to happen very fast so that mutations don’t mess up the work done in each step. Here is coyne’s explanation-

One might ask this reasonable question: “Well, if the nascent antifreeze protein is just sitting there and not doing anything before it becomes active, why isn’t it inactivated by mutations?” That’s a good question, and one answer is that the process took place reasonably quickly so that mutations (which are, after all, rare) didn’t have time to turn the dark blue protein core into gibberish. And once that core formed, duplication of the Thr-Ala-Ala would be rapid, promoted by natural selection because more repeats confer greater antifreeze activity.

And lastly, it’s not clear whether small concentrations (starting from one case?)of the “thr-Ala-Ala” are effective enough to be “selected” for their anti freeze properties.

All I will say is that I don’t have as much faith in serendipity and coincidence as Jerry does. And that somebody like James Shapiro would explain this entire scenario differently in a more plausible way… (not that I would agree with him :slight_smile: ).

No, he’s describing the equivalent of a particular bridge hand, every one of which is vanishingly unlikely.

More plausible to you.

Can you calculate and establish this is the case?
Or is it how you justify these incidents to yourself?

And him too at the least. Perhaps to other scientists who agree with him too.

It’s an analogy. Do you understand analogies? What this one means is that you’re going about probabilities all wrong. You would try to calculate the probability of this particular sequence of events happening, but you need the probability of some sequence of events that would produce some sequence selectable for some function.

Are there any?

So it’s how you justify scenarios like this in yourself and others.I can understand that. However, it need not be true or relevant to the case being considered.

The third way website mentions about 51 scientists who think along these lines.

But not plausible enough to do the work of testing a hypothesis.

Too difficult, or could it be a lack of faith?

Think. Any that do anything along those lines?

I find it fascinating that engineers, of all people, can excuse their total lack of action.

Have you read the comments above? Do you know who we are discussing?
Do you know what we are discussing?