Do All Evolutionary Theorists Agree that Macroevolution Is Just Repeated Rounds of Microevolution?

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In another discussion, I was asked to provide documentation for my statement that some evolutionary theorists questioned the view that macroevolution was merely the addition of many rounds of microevolution.

Here is the essence of the exchange, drawn from three posts:

Michael Okoko:

“Macroevolution is microevolution plus microevolution plus microevolution plus plenty time.”

Eddie:

“… [that] has been disputed by trained evolutionary theorists. Some believe that other mechanisms are in play.”

Michael Okoko:

“This is false. Every evolutionary biologists accepts that mutations, natural selection, genetic drift and others all operate on a grand scale. Cite evidence to show otherwise.”

(*Note: I had not claimed that any evolutionary biologist said that mutations, natural selection, drift etc. ceased to operate on the grand scale, but only that some evolutionary biologists said that there were, or at least might be, additional mechanisms required for the major changes observed in macroevolution.)

Now, I move to the evidence I was asked for. Please note – I say this because certain people here regularly misrepresent what I’m claiming – I’m not claiming as a certainty that macroevolution isn’t just repeated rounds of microevolution. I’m merely claiming that some evolutionary theorists have expressed opposition to, or doubt about, that claim. So if I can prove that some evolutionary theorists have done this, I have met the burden of proof, and shown that Michael Okoko has wrongly oversimplified the range of views held in the field.

I will for the time being settle for just three examples:

Donald Prothero:

“If species sorting is real, then the processes operating on the level of species (macroevolutionary
processes) are not necessarily the same as those operating on the level of individuals and populations
(microevolutionary processes). In other words, macroevolution may not just be microevolution scaled
up.”

“Punctuated Equilibrium At Twenty: A Paleontological Perspective,” The Skeptic, vol. 1, no. 3, Fall 1992, pp. 38-47.

https://pdfs.semanticscholar.org/e19f/97f8dc5f47568e06005109f219792a9b058a.pdf – last page.

Eugene Koonin:

“For all its fundamental merits, Modern Synthesis is a rather dogmatic and woefully incomplete theory… Modern Synthesis makes a huge leap of faith by extending the mechanisms and patterns established for microevolution to macroevolutionary processes…”

The Logic of Chance: The Nature and Origin of Biological Evolution (FT Press, 2012), pp. 18-9.

Erwin and Valentine:

“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.”

The Cambrian Explosion: The Construction of Animal Biodiversity (Roberts & Company Publishers, 2013) , p. 10.

Note the range of dates here, covering 21 years. This shows that reservations about the “macro is just repeated rounds of micro” claim have been not just a short-term fad, but a recurring theme in the literature.

Again, the question is not whether Michael Okoko’s original claim about micro- and macroevolution is wrong. The question is whether Mr. Okoko’s further claim that all evolutionary biologists agree with him is wrong. It appears to be the case that his further claim is wrong, whether his first claim is true or not.

Mr. Okoko, do you agree that these evolutionary theorists appear to have a view different from your own?

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It seems to me there’s two ways to understand this question of whether microevolution can result in macroevolution, the definitional and the physical/biochemical.

By definition, microevolution is evolution below the species level. That is evolutionary changes that take place within a population, but which do not result in changes in the number of species. According to this definition, microevolutionary change cannot by definition result in macroevolutionary change. Because the definition of macroevolution is evolution above the species level, that is changes in the number of species.

But notice this is not because the kinds of physical or chemical changes that occur during microevolution cannot result in macroevolutionary change (changing morphology or behavior without causing emergence of reproductive barriers), it is just that should they do so we would stop calling them microevolutionary and instead call them macroevolutionary changes.

So we have simply come up with a way of classifying evolutionary changes depending on what their effects amount to, we have not dictated to reality and commanded the changes to be incapable of accumulating into macroevolutionary changes.

So it now becomes clear that yes of course microevolutionary changes, when considered simply as the physical and biochemical changes that happen to a pupulation as it evolves over generations, really can result in macroevolutionary change, that is cause the emergence of reproductive barriers between subpopulations resulting in speciation and thus macroevolution.

So, should a particular physical and biochemical change not result in the emergence of a new species, we will classify it as a microevolutionary change.
But if it does result in the emergence of a new species, we will classify it as a macroevolutionary change.
But then microevolutionary changes really can pile up such that, when one more of such changes occurs, it’s “the final drop that causes the beaker to overflow”, and results in a reproductive barrier of some kind, thus speciation and macroevolution has occurred. But then that final change would be classified as macroevolutionary, and the preceding ones as microevolutionary. Even though we can of course understand that the final macroevolutionary change would not have resulted in speciation had those other preceding microevolutionary changes not occurred first.

I think it should of course also be emphasized that speciation is a gradual process, I did not mean to imply with the above that sudden from one generation to the next a new species is born by the spontaneous emergence of a total reproductive barrier where gene flow between populations drops suddenly to 0, as opposed to gradually decreasing over time.

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Most evolutionary biologists don’t even use the macro/micro distinction.

In any group it is possible to find outliers: there are black men in the white supremacist Proud Boys.

If it wasn’t midnight here I’d check your examples to ensure that they do represent what you’re suggesting and are not either (a) ID or other supernaturalist proponents or (b) quote-mines where the argument is laid out in the form “It appears as though A is not the case… but when we look more closely we see that in fact A is the case, albeit in a way we hadn’t known about before” that has been bisected at the ellipsis.

Maybe tomorrow.

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The fact that you don’t know the ideas of Prothero, Erwin and Valentine, and Koonin well enough to know that none of them are ID proponents, and that Prothero in particular is an outspoken ID opponent, suggests to me that you don’t read all that broadly in evolutionary theory.

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Even if that’s true – which I doubt – it’s completely irrelevant to the point of my column. My argument was not that most evolutionary biologists use the distinction. My argument was that, of the evolutionary theorists who do use the distinction, some disagree with Michael Okoko. He said or strongly implied that none would disagree with him.

Your comparison is invidious.

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That’s not the question Eddie is asking, so you probably shouldn’t go there. The question is whether there are processes involved in macroevolution that can’t be reduced to microevolution. And I think there are, species selection being the main one. Eddie, for once, is right. Of course that doesn’t mean that a lot of macroevolution can’t be reduced to piled up macroevolution; it certainly can. Adaptation is microevolutionary.

Sure it can. Speciation is a microevolutionary process, as it results from changes in allele frequencies in one or more populations, as you said. I don’t think your definitional argument works, because if macroevolution were piled up microevolution, we wouldn’t have to stop calling it microevolution. Again, the question isn’t whether macroevolution can result from microevolution, it’s whether it exclusively results from microevolution.

It’s popular mostly among paleontologists. But they’re evolutionary biologists, aren’t they? And you can use me as an example of a neontologist who thinks the distinction is real.

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I agree.

And more specifically, it doesn’t mean that the genetic mechanisms underlying interspecies selection aren’t the same as those underlying intraspecies selection.

So, Eddie, what’s your point?

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Not according to that definition of microevolution. I was once fed this definitional argument from Simon Gunkel (a german population geneticist), as I argued that of course microevolution could build up into macroevolutionary change, at which point he insisted that if we define microevolution as evolution below the species level, then by that definition it is evolution below the species level.

But (and this is my argument) this is a synthetic restriction, since obviously some mutation doesn’t have some sort of rule hanging over it telling it not to result in macroevolutionary change.

So we’ve run into a problem now, as there seem to really be multiple ways to understand these terms, and when people aren’t clear in what sense they use them, you can waste inordinate amounts of time arguing about it. And someone can go and pull up fifty quotes from evolutionary biologists using the term in different ways, which appear to all contradict each other, with some saying you definitely can get microevolution to build up into macroevolution, and others saying you definiteily can’t do that by definition, and still others saying you some times can. So now we have to go and ask all these people to try to make clear in which sense they are using the term, and if they were to use it in the sense some other guy was using it, would they still agree or disagree?

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I believe you have hit on the problem. That’s a poor definition of microevolution, and you have pointed out some of the reasons why it’s not good. I would prefer “allele frequency changes in populations”, both more descriptive and in more common use.

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I think this will be the only substantive conclusion of this thread. For me, “evolution below the species level” crosses a boundary that takes us outside scientific discourse. It feeds on the emotional/intuitive “sense” that there is something “different” about “macroevolution.” It takes us into La La Land.

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@John_Harshman has already done a great job of responding (to @Rumraket) so I’ll just +1 those then add one meta thing.

I think we should be aware that there are some semantic pitfalls in the whole conversation that make it hard to say that the claim in the title of the thread is “wrong.” Phrases like “macroevolutionary change” are a hairs breadth away from affirming a very common perception that there is something fundamentally distinct about “macroevolution.” IMO this is a road to nonsense. If we talked this way about mammalian embryonic development, we would give the impression that the development of the brain is conceptually distinct in such a way as to be uncoupled from the cellular processes that shape it. Instead, we talk and argue and theorize about the influences on brain development, welcoming concepts at multiple scales and even at scales that seem “non-physical” (e.g. behavior and experience). My point being that if an evolutionary theorist does say that “macroevolution is just repeated rounds of microevolution” they would not (and do not) mean that macroevolution is so conceptually distinct that “microevolution” is somehow irrelevant or metaphysically disconnected.

That, FWIW, is how I think about evolution. “Microevolution” explains the constant movement of organisms and lineages through design space and genome space. What it doesn’t explain, by itself, is why and how we have the tree of life that we do, as opposed to the myriad trees we could have. All by itself, differential reproduction and variation don’t explain the why and how of the seemingly constrained/limited animal body plans. We need additional conceptual resources to ask and answer those questions.

Final note: @ProfBravus was wrong to even speculate that the biologists you cited were not legit, but he was right in his claim that biologists very rarely even talk about micro/macroevolution. I think it is fair to say that this kind of “debate” is hundreds of times more popular in conversations with/among religious people than it is in any scientific context.

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Not sure what you mean there. Genetic mechanisms don’t underly selection. They would underly mutation. Do you mean that the genetic mechanisms underlying the genetic variation, whether between or within species, upon which selection acts are the same? Or perhaps that the sorts of variation are the same? I would agree if so. But who knows what Eddie is talking about?

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I phrased it badly. A better way would be, “The genetic mechanisms producing the variation on which both interspecies and intraspecies selection are the same.”

I don’t. Maybe Eddie can explain why these terms are so important in the culture war against evolutionary biology.

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Yes, we do.

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I think most would agree that macroevolution arises from repeated rounds (i.e. continuous) microevolution. However, to say “just” is too reductive. Macroevolution is not “merely” microevolution.

Moreover, and not possible to neglect, there are multiple valid meanings of macroevolution, and also of microevolution. Though I think my answer is valid, it is also likely vacuous (as is the question itself) without specifying our definitions further.

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He wrote “most.”

The distinction exists in the literature, but it seems to me that it’s so rarely used that authors see the need (and I do too) to define the terms right away. See the abstract below. Note that the abstract is not from a research paper but from a commentary on a research paper.

I found that abstract by searching PubMed for “macroevolution microevolution” which yielded about 80 hits. Just “microevolution” about 1100. Just “macroevolution” about 950. For comparison, “phylogenetic” generates more than 150,000 hits. These are not commonly used terms. @ProfBravus is right.

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I wouldn’t. Or not only from that.

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That’s consistent with what I wrote, because I stated that this is not the whole story, it isn’t “just” this.

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So you would agree that not all macroevolution can be reduced to microevolution?

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I’ve stated the same in my first post here. Did you read beyond the first sentence?

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