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

Since it has repeatedly been claimed here by several people that there are no significant disputes about mechanism among evolutionary theorists (i.e., that all disputes are only over minor details or issues “on the periphery”), I offer here a clear example of a serious dispute regarding mechanism between evolutionary biologists.

This is a review by Jerry Coyne of an article by Davidson and Erwin. The review is published in Science, a prestigious journal.

The link is:

The point here is not which side in the dispute is correct; the point is that there is a dispute, that the dispute is over mechanisms of evolution, and that it is not a dispute over a trivial “detail” question or a “peripheral” question but over a major difference regarding the causes of evolutionary change at the higher taxonomic levels.

Which is what I said an earlier discussion to Chris Falter – that such disputes exist. He seemed to contest this.

I could provide many more debates of this sort, but I don’t intend to waste my time digging them all up. (The sort of person here who will not accept this example as proof of the existence of serious disagreement over evolutionary mechanisms would not accept any other example I could dig up.)

For people who are interested in the broader questions behind this dispute, there is an informative article by Erwin:


This was 2006, where does it stand in 2019? Perhaps this is now longer relevant because of new data?

For what it’s worth, the position advanced by Davidson and Erwin in their 2006 review (evolution of animal body plans through assembly of gene regulatory network “kernels” in a process disctinct from “microevolutionary patterns”) is identical to that which Erwin advanced with James Valentine in 2013, in which they wrote:

“One important concern has been whether the microevolutionary patterns commonly studied in modern organisms by evolutionary biologists are sufficient to understand and explain the events of the Cambrian or whether evolutionary theory needs to be expanded to include a more diverse set of macroevolutionary processes. We strongly hold to the latter position.
Erwin D.H. & Valentine J.W., 2013, The Cambrian Explosion: The Construction of Animal Biodiversity, p. 10; my emphasis


What makes you think this is a major disagreement? Looks very minor to me.


It’s a rather useless point. Are you more interested in scoring points or learning the truth (plagiarized from @glipsnort at a different site)?


It’s not “minor” when one evolutionary theorist suggests that different mechanisms operate at different taxonomic levels, and another denies it. For more background, see the other article I referenced.

So what are these mechanisms, and how do they differ from the theory they are arguing against?

Seems minor to me. Just normal squabble between scientists on a minor detail, as we commonly do.


You’re changing the goalposts. Whether or not an observation is useful and whether or not it is true are two different things. Is it true or false that evolutionary theorists sometimes have major disputes about mechanisms?

READ THE BLOODY ARTICLE, and then you’ll know. Or is even a one-page article too long for your anti-book patience?

The observation of disagreements isn’t useful. Again, are you trying to score points or learn the truth?

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If you think it’s minor, you know less about evolutionary theory than you think you do. I suggest you sit down and read Gould’s Structure of Evolutionary Theory, or at least large chunks of it. You clearly lack a big-picture framework when you talk about evolution.

Why do you think that constitutes a major dispute in evolutionary theory? You seem to be only interested in scoring cheap rhetorical points.

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Chris denied by implication that such disagreements existed. This example (one out of many that could have been used) shows that he is wrong.

Actually all it shows is how little you understand the overall theory and how desperate you are to try and gain a cheap rhetorical “victory”.


I read the article and saw no mentions of mechanisms. If you think I am wrong, then quote the paper. For example:

So what is the mechanism of “architectural alterations”? How do they differ from the standard types of mutations that are already a part of the theory? It would seem that genetic recombination is more than adequate for producing these changes. It isn’t clear at all how Davidson and Erwin are proposing anything different from standard microevolutionary events.


Again, you appear to be more interested in scoring points than in learning the truth.

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The irony here is breathtaking.

Maybe he didn’t read the paper. Maybe he can’t understand the paper.

They’re not, in the sense that all the changes they’re talking about are ultimately caused by single-nucleotide mutations, gene duplication, etc. The difference is that Davidson and Erwin are thinking about developmental/morphological change at different hierarchical levels, and point out that only studying one level (microevolution/speciation) doesn’t necessarily tell us everything about the other levels. The mechanisms of genetic change are the same, just the effects and how they relate to morphology might be very different.

I think this is generally true, but like Coyne, I’m a bit skeptical about how this can be applied to our man-made classification system. I don’t think it’s as clear-cut as Figure 3 of Davidson and Erwin’s paper might suggest.


DUUH. Did you read even the first sentence?

“In their review of the evolution of animal
body plans, Davidson and Erwin (1) proposed
that the origin of higher level clades,
such as phyla, involves mechanisms other
than the normal microevolutionary processes
thought to cause speciation.”

Isn’t the word “mechanisms” in the most pronounced possible place – the first sentence of the article – for you to notice it? To help you, I have employed boldface and italics.

Doesn’t the placement of that statement in the first sentence of a short review article suggest that the article will have something to do with mechanisms?

And doesn’t Coyne go on to dispute the claim about mechanisms?

Sheesh. If this is how well science researchers can understand what they read, something is very lacking in science education.