An Example of a Substantive, Non-Trivial Dispute Among Evolutionary Theorists

I noticed it, but I failed to find any mention of what these other mechanisms are. Can you find them in the paper?

Thanks, evograd. You understand why I selected the article.

As you point out, it is possible to be skeptical of Davidson and Erwin. But as I’ve been striving to say, I’m not defending Davidson and Erwin or anyone else in particular. I’m merely pointing out that serious disagreement about some things exists. And I am meeting with incredible resistance to what should be an obvious point. It’s as if anything that Eddie says must be resolutely opposed, even when it’s an almost tautological point, i.e., that scientists from time to time have major theoretical disagreements with their peers in their fields.

In other words you’re trying to manufacture a major disagreement over a relatively minor disputed aspect of ToE. Pathetic rhetorical shuffle-dancing but pretty typical.

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How is it “resistance” to ask you how the mechanisms proposed by Davidson and Erwin are different from the mechanisms already in the theory?

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I haven’t seen anyone deny that. What you’re getting pushback on is your claim that there is “serious disagreement about some serious things”. That’s the claim that you’re struggling to come up with examples for. I don’t think this exchange of articles is a particularly good example, because for a start, it only serves to highlight a disagreement involving 3 people, not the entire field, and it’s from back in 2006. Now, and looking at the bigger picture of how this work is received in the field, I think it’s not particularly contentious, and any lingering disagreements are on how Phyla should be considered, which in itself isn’t a particularly big deal.

There is a middle ground between “trivial” disagreements and “major” disagreements, you know.

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In what sense is this “serious”? Seems banal to me.

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This paragraph, taken from a later paper by the same authors (Erwin and Davidson, 2009), explains what they mean when they say their mechanisms are different to/incompatible with “microevolution”:

Uniformitarianism is the concept that the processes of geology have not changed over time, and thus ‘the present is the key to the past’; this is also an implicit assumption of most evolutionary theory. Strict microevolutionary theory assumes that changes in gene frequencies are sufficient to explain all evolutionary patterns. In terms of developmental GRN structure, this concerns mainly changes at the periphery of GRNs. The macroevolutionary theories favoured by many palaeontologists are similarly ahistorical, focusing on selection operating at the level of species and clades57,58,59,60, but with no historical vector. Neither microevolution nor macroevolution takes into consideration the impact of past changes in developmental GRNs on the future course of evolution.

In other words, they’re proposing that developmental constraints exist, which is now a perfectly mainstream position.

Eric Davidson was many things, but his disagreements with mainstream evolutionary theory were never “banal.” This 2011 paper is open access:

From the paper:

Views of body plan evolution

Of the first of these approaches (e.g., Hoekstra and Coyne, 2007), I shall have nothing to say, as mechanistic developmental biology has shown that its fundamental concepts are largely irrelevant to the process by which the body plan is formed in ontogeny. In addition it gives rise to lethal errors in respect to evolutionary process. Neo-Darwinian evolution is uniformitarian in that it assumes that all process works the same way, so that evolution of enzymes or flower colors can be used as current proxies for study of evolution of the body plan. It erroneously assumes that change in protein coding sequence is the basic cause of change in developmental program; and it erroneously assumes that evolutionary change in body plan morphology occurs by a continuous process. All of these assumptions are basically counterfactual. This cannot be surprising, since the neo-Darwinian synthesis from which these ideas stem was a pre-molecular biology concoction focused on population genetics and adaptation natural history, neither of which have any direct mechanistic import for the genomic regulatory systems that drive embryonic development of the body plan.

I don’t know how readers here cash out the adjective “banal,” but saying that the underlying assumptions of the view one opposes lead to “lethal errors” and are “basically counterfactual” goes well beyond the normal range of “banal” for me. :wink:

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But it wasn’t, at one time. At one time, it was resisted. So there was a debate among evolutionary biologists over whether such constraints existed. And I don’t think it’s a trivial question whether or not such constraints exist. It’s an important insight. Therefore, it’s a good thing that debate was allowed; it’s a good thing that the majority didn’t just shout down the minority and tell them that they should stick with “standard evolutionary theory.” The existence of a diversity of viewpoints improved our understanding.

And if you say, well, since this is now settled, there is no longer any debate there, well, there are always new things that scientists in any field debate about when old debates are settled. That’s all that I was saying, that evolutionary theory is a field in ferment, that there is always new thinking going on, that there are always disagreements. That is almost a tautology, for any scientific field.

I could go to the trouble to dig up articles that speak of strong disagreements today in evolutionary biology. But it’s not worth my while. I can see from the way this evidence is treated, that any evidence of debate that I presented would be belittled, called “banal”, etc.

You haven’t read the ARTICLE. The document to which you referred was a LETTER. There was a second LETTER, linked from on the page with the first.

You haven’t even bothered to read the article, nor have you bothered to read the second letter, correct?

The second letter makes the point that the real scientists here have been making in spades.

Amazing. You clearly know that your claim about Chris is false, because you clearly know the difference between implication and inference:

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@Eddie,

I think you need to choose yet another topic.

While it is tempting to say this article describes a watershed that separates one cluster of Evolutionists from another cluster … I am doubtful that many Evolutionists of any stripe would disagree with the general validity of the points being raised in the article.

Let’s read the Conclusion-of-the-Conclusion:

“Much of this discussion has focused on pattern, rather than process. Yet the greatest opportunities for progress in macroevolution may come from comparative developmental biology ( 25). Here the questions range from whether developmental involvement in speciation is distinct from adaptive intraspecific evolutionary change, to the relationship between major morphological shifts and evolution of developmental control genes. The exploding comparative data on developmental evolution promise surprising insights into the basis for macroevolutionary patterns.”

There just isn’t a polarization around this topic…

In my personal view, the key issue: what kind of changes happen that trigger reproductive incompatibility… which is the fundamental factor for how an existing population continues to occupy a niche while a branch population starts down a path of rapid differentiation!

You’re reading the wrong article. The article I made the claim about is the first one I linked to. The other article was for supplementary information.

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Yet you don’t, because your approach to scholarship is laughably shallow.

I’m pointing out the shallowness of your approach, in that you didn’t even bother to read the original article and the authors’ reply to Coyne. You’re also so unfamiliar with the literature that you can’t distinguish between an article and a letter to the editor.

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The Coyne piece I linked to is a one-page review ARTICLE. The word “article” has a broader range of meaning than you seem to be giving it. But pedantry is something I’ve come to expect from you, since meeting someone halfway regarding terms, when the meaning is clear enough, is alien to your combative nature.

No. It is clearly labeled, in large font at the top, as a “Comment.” You really don’t have a clue.

The word “article” is used below, but it is in boilerplate legalese attached to every PDF downloaded from Science.

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@Eddie,

Okay… I read the right article this time. And its final words include this mouthful:

" The earliest ones were likely hierarchically shallow rather than deep, so that in the beginning adaptive selection could operate on a larger portion of their linkages. Furthermore, we can deduce that the outputs of their subcircuits must have been polyfunctional rather than finely divided and functionally dedicated, as in modern crown group dGRNs. A general result of these arguments is that considerations of evolutionary change in dGRN structure may at last provide a unified conceptual framework for understanding the stages of crown group evolution, and in the same breath the sequential history of change that has produced the different hierarchical levels of animal dGRNs."

“But some things never change, and a principle that must have been obtained from early in metazoan evolution is that developmental jobs are controlled through the logic outputs of genetic subcircuits. Thus, how evolution of the animal body plan has occurred is a question that in the end can only be addressed in the terms of transcriptional regulatory systems biology.”

  1. I would agree that there appears to be good logic for examining two different worlds of evolutionary processes.

  2. I would agree that the two methodologies or targets of methodologies are rather mutually exclusive.

  3. But I do not agree that these distinctions lead to a break of Evolution into two different societies or “camps”. I would be surprised if any of the Evolutionists on this blog, for instance, interpret the views represented in the article as a “We versus Them” struggle.

There is a value to examining all sorts of mutually exclusive avenues of research. The fact that there are multiple avenues is not a discontinuity … but rather the article highlights a multiplicity of areas of ignorance.

Science is not like metaphysics or theology, where camps of individuals battle inconclusively (and for eternity) on something that can never be known. In Science, we battle for dominance… but rarely to the exclusion of all the other avenues of information and discovery.

TYPO: The word “science” was used twice in the 2nd to last sentence. That has been corrected.

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More typically, we battle to be the first to find an answer that parties to a disagreement have already agreed will resolve said disagreement.

Eddie appears to be unable to grasp the concept of data resolving disagreements.

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That’s why I said this example wasn’t very good, since clearly your goal is to raise examples of current major disagreements.

Is this supposed to be a “gotcha”? I think you have a habit of making these kinds of statements that no one disagrees with while acting as though we actually do disagree.

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This looks to me like an example of confusion about what evolutionary theory is supposed to explain. If you want your theory of evolution to explain how limbs develop, then you’re going to need more than a theory of evolution that includes mutations an natural selection, you’re going to need a theory that encompasses development. That means biophysics, cell, and developmental biology. But it isn’t clear to me those need to be included in evolutionary theory in order to be able to explain how macroevolution is different from microevolution.

I some times get the impression that the people who insist evolutionary theory needs to be extended want more from it than merely explaining how populations change(explain what “forces” that cause this change, mutations and population mechanics like selection etc.), they also want it to explain the biophysics of cell and developmental biology.

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The sense I get is that they start with an overly simple (to put it diplomatically) model of how evolution works, and then try to carve out a space for themselves as something different than what is in that model.

In the case of Davidson and Erwin, they appear to portray microevolution as an accumulation of substitution and small indel mutations without any drastic change in gene function, gene copy number, or synteny. As Coyne (correctly) notes, gene duplication and recombination events would be part of variation within a population and a part of divergence at the level of species. This is further made plain by understanding that taxonomic divisions are largely arbitrary and by-products of time since common ancestry rather than mechanism.

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