A Question about Evolutionary Theory

Punctuated Equilibrium

Incl. intelligent design, belief in divine creation

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A Question about Evolutionary Theory

#1  Postby Zadocfish2 » Sep 28, 2014 12:04 pm

As I read some of the materials linked to from this site, namely this one: http://corior.blogspot.com/2006/02/part ... ution.html . In it, it mentions a fact that I would assume is very common in Creationist literature: quote-mining scientists arguing about the differences between Punctuated Equilibrium vs Gradual Descent, and putting forth that proponents of the latter are denying evolution as a whole.

Now, to be honest, as much as I love biology and evolutionary biology as a whole, I mostly only know anything about the Gradual Descent model. To better understand what is being discussed in this article and others, and as a reference for any Creationist users this site may have, can someone explain or post a link explaining how the Punctuated Equilibrium model is thought to work?
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Re: A Question about Evolutionary Theory

#2  Postby hackenslash » Oct 27, 2014 3:32 pm

It's pretty simple, really. In very simple terms, punctuated equilibrium is simply the idea that there are instances in which major changes in environment lead to rapid, large-scale evolution. Creatinionists often talk about it as an exception to evolution, when in fact it's just elucidating the fact that evolution isn't always gradual, as was thought for a long time. Where, for example, there's a major catastrophe, such as the bolide impact that put such a cramp on the lifestyles of the dinosaurs, niches open up and evolution proceeds at an increased rate.

The best source for this is probably Gould's book of the same title.
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Re: A Question about Evolutionary Theory

#3  Postby epepke » Oct 27, 2014 3:40 pm

Historically, punctuated equilibrium was the favorite idea of Stephen Jay Gould. He used to write a lot of popular books that were pretty good. He had a lot of arguments with Richard Dawkins before Dawkins started writing a lot about religion, which was after Gould died.

Gould was popularly influential. However, his ideas weren't taken very seriously at all outside the United States. At best they were considered a minor wrinkle. It did seem to me that they were a minor wrinkle, and Gould overstated the importance of the idea.

There's also the possibility, at which some scoff, that PE was ideologically motivated. Gould was an outspoken Marxist, and he was uncomfortable with the idea that competition was important in evolution. I think there might be something to this idea, though it's hard to read the mind of a dead person.
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Re: A Question about Evolutionary Theory

#4  Postby Darwinsbulldog » Oct 27, 2014 10:17 pm

The irony in the Dawkins-Gould debate is that they were both right. Evolution is gradual, and can also be rapid. It really depends when and where you look. Change the scale one way, and you have PE. Change the scale the other way, and it appears gradual. And as others have said, some disaster that kills off a bunch of organisms is going to leave a lot of vacant niches around, and so there is "room" to evolve. However, vacant niches are not always filled quickly. Sometimes 20+ millions of years can pass before an ecology recovers. So each major extinction is different. Some appear to be sudden catastrophes, and others slow declines. This is in part due to scaling-the time period one looks at.
I suppose early evolutionists, including Darwin did not really think evolution had to be always gradual [because Darwin saw very rapid change in captive breeding programs], but emphasized gradualism to get the public away from the catastrophic "Flud-like" mind-set the church had drilled into the public's imagination. Such a mind-set is not helpful when trying to understand how natural selection works.
Of course now that we know about genetics, the mechanisms that create "hopeful monsters" are mundane, natural and explainable. The basic mutation that creates the turtle plastron is a good example. Basically, it is a change in timing of rib growth. The ribs grow out "flatter", and thus the shoulder girdle ends up inside [instead of outside] the rib cage. The loss or gain of vertebrae is also quite simple, although it produces quite profound morphological change. Innovations like the evolution from radial to bilateral symmetry [while rare] are also sudden, but quite natural 'salutations". Thus the monster is not hopeful, but inevitable, given enough time. It can happen tomorrow, or in a billion years.
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Re: A Question about Evolutionary Theory

#5  Postby Fenrir » Oct 27, 2014 11:06 pm

Think of it like geology. Mostly gradual accretion interspersed with singular rapid events. Volcanoes and earthquakes have significant local effects but do not overwhelm the overall gradual process.

Look at the grand canyon. The canyon itself is a singular event which occurred over a relatively short timespan however the strata it is embedded in are the result of long term gradual accretion.
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Re: A Question about Evolutionary Theory

#6  Postby epepke » Oct 28, 2014 12:26 am

Darwinsbulldog wrote:The irony in the Dawkins-Gould debate is that they were both right. Evolution is gradual, and can also be rapid. It really depends when and where you look.


They were both right, by Dawkins' perception. Dawkins was the one who kept going on about how gradualism wasn't the same as constant speedism, which is an excellent point. Gould, however, behaved as if PE were something newly discovered, amazing, and qualitatively different. He never quite admitted that he was talking about saltations, and he used to sputter a lot when accused of it, but he behaved as if in his heart of hearts he did mean something like that, something truly amazing and completely different.

From my point of view, he was engaging any self-aggrandizing academic hype.
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Re: A Question about Evolutionary Theory

#7  Postby Lowpro » Oct 28, 2014 12:49 am

Dumb question. Does anyone know how Gould's PE meshed with Sewell Wright's statistical models for genetic flow? If I were exposed to those models before PE I would have thought PE to be inevitable, yet iirc PE was proposed later.
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Re: A Question about Evolutionary Theory

#8  Postby Darwinsbulldog » Oct 28, 2014 2:24 am

epepke wrote:
Darwinsbulldog wrote:The irony in the Dawkins-Gould debate is that they were both right. Evolution is gradual, and can also be rapid. It really depends when and where you look.


They were both right, by Dawkins' perception. Dawkins was the one who kept going on about how gradualism wasn't the same as constant speedism, which is an excellent point. Gould, however, behaved as if PE were something newly discovered, amazing, and qualitatively different. He never quite admitted that he was talking about saltations, and he used to sputter a lot when accused of it, but he behaved as if in his heart of hearts he did mean something like that, something truly amazing and completely different.

From my point of view, he was engaging any self-aggrandizing academic hype.


I think both men were prim a-donnas! Not exactly a rare trait among professors, especially with a public profile. I think both men straw-manned each other's arguments to some degree. And what they didn't straw-man, the media did. The fact is that [even after controlling for artifacts caused by scaling, he demonstrated clear evidence of PE is the fossil record of some mollusc groups. And in Ontogeny and Phylogeny he more or less predicted the discoveries of evo-devo.
Likewise Dawkins Gene-Centered approach undoubtedly paid dividends as well. I don't think either totally denied the position of the other, just the emphasis. Until William Hamilton [and dawkins credits his views to Hamilton, George Williams etc] some evolutionists were thinking along some 'woolly" lines like "species level selection]. And yet other did deny natural saltation because they could not see a mechanism, and it was too "philosophically" close to creationism.

But the extended synthesis takes care of all these issues, including epigenetics. :thumbup:
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Re: A Question about Evolutionary Theory

#9  Postby Spearthrower » Oct 28, 2014 2:50 am

Zadocfish2 wrote:As I read some of the materials linked to from this site, namely this one: http://corior.blogspot.com/2006/02/part ... ution.html . In it, it mentions a fact that I would assume is very common in Creationist literature: quote-mining scientists arguing about the differences between Punctuated Equilibrium vs Gradual Descent, and putting forth that proponents of the latter are denying evolution as a whole.

Now, to be honest, as much as I love biology and evolutionary biology as a whole, I mostly only know anything about the Gradual Descent model. To better understand what is being discussed in this article and others, and as a reference for any Creationist users this site may have, can someone explain or post a link explaining how the Punctuated Equilibrium model is thought to work?



Odd! Usually Creationists leap on punctuated equilibria as scientific jargon for the days of creation! :)

Punctuated equilibrium just means that species will exhibit little morphological change over long periods of environmental stasis, but will change rapidly, geologically speaking, when encountering new niches or facing new environmental challenges.

Creationists willfully misinterpret this along the lines of Richard Goldschmidt's 'Hopeful Monster', where dramatic evolutionary changes occur in just one generation - think Crocoducks. Basically, Creationists manage to simultaneously argue that this pokemon form of evolution is how scientists erroneously define evolution, and also declare that this is actually what is seen in the fossil record.

This exposes how Creationists ignorantly perceive scientific theories as loose threads which they just have to pull on to unravel. Consistency isn't important, it's the undermining of an evolutionary account that matters.
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Re: A Question about Evolutionary Theory

#10  Postby Spearthrower » Oct 28, 2014 2:59 am

Lowpro wrote:Dumb question. Does anyone know how Gould's PE meshed with Sewell Wright's statistical models for genetic flow? If I were exposed to those models before PE I would have thought PE to be inevitable, yet iirc PE was proposed later.


It's been a while, but I remember him using the term 'Wright Break' - Iirc it was in a paper called 'Is a new and general theory of evolution emerging'. I think the term was concerned with how Wright's models produced macroevolutionary trends partly distinct from microevolutionary processes. So Gould was at least aware of Wright's models and considered them supportive to punctuated equilibria.
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Re: A Question about Evolutionary Theory

#11  Postby Darwinsbulldog » Oct 28, 2014 3:12 am

Spearthrower wrote:
Zadocfish2 wrote:As I read some of the materials linked to from this site, namely this one: http://corior.blogspot.com/2006/02/part ... ution.html . In it, it mentions a fact that I would assume is very common in Creationist literature: quote-mining scientists arguing about the differences between Punctuated Equilibrium vs Gradual Descent, and putting forth that proponents of the latter are denying evolution as a whole.

Now, to be honest, as much as I love biology and evolutionary biology as a whole, I mostly only know anything about the Gradual Descent model. To better understand what is being discussed in this article and others, and as a reference for any Creationist users this site may have, can someone explain or post a link explaining how the Punctuated Equilibrium model is thought to work?



Odd! Usually Creationists leap on punctuated equilibria as scientific jargon for the days of creation! :)

Punctuated equilibrium just means that species will exhibit little morphological change over long periods of environmental stasis, but will change rapidly, geologically speaking, when encountering new niches or facing new environmental challenges.

Creationists willfully misinterpret this along the lines of Richard Goldschmidt's 'Hopeful Monster', where dramatic evolutionary changes occur in just one generation - think Crocoducks. Basically, Creationists manage to simultaneously argue that this pokemon form of evolution is how scientists erroneously define evolution, and also declare that this is actually what is seen in the fossil record.

This exposes how Creationists ignorantly perceive scientific theories as loose threads which they just have to pull on to unravel. Consistency isn't important, it's the undermining of an evolutionary account that matters.


Real crocoducks, y'all:-

Stuart, Y. E., et al. (2014). "Rapid evolution of a native species following invasion by a congener." Science 346(6208): 463-466.
In recent years, biologists have increasingly recognized that evolutionary change can occur rapidly when natural selection is strong; thus, real-time studies of evolution can be used to test classic evolutionary hypotheses directly. One such hypothesis is that negative interactions between closely related species can drive phenotypic divergence. Such divergence is thought to be ubiquitous, though well-documented cases are surprisingly rare. On small islands in Florida, we found that the lizard Anolis carolinensis moved to higher perches following invasion by Anolis sagrei and, in response, adaptively evolved larger toepads after only 20 generations. These results illustrate that interspecific interactions between closely related species can drive evolutionary change on observable time scales.

http://www.sciencemag.org/content/346/6208/463.abstract
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Re: A Question about Evolutionary Theory

#12  Postby Spearthrower » Oct 28, 2014 3:17 am

Stuart, Y. E., et al.


Et all here clearly means Cameron, K., and Comfort, R.

:D
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Re: A Question about Evolutionary Theory

#13  Postby epepke » Oct 28, 2014 3:30 am

Darwinsbulldog wrote:I think both men were prim a-donnas!


No doubt, my point being that the whole kerfluffle in the first place reduced, mostly, to academic games. Very little, if any, of the different reduced to science. I think we're in agreement about that, but I always seem to touch upon meta-aspects. I want to underscore the idea that it was not (or at least not necessarily) gradualism versus punctuated equilibrium. It's also (mainly, mostly, or all) about whether the distinction makes any meaningful scientific sense.

Not exactly a rare trait among professors, especially with a public profile. I think both men straw-manned each other's arguments to some degree. And what they didn't straw-man, the media did. The fact is that [even after controlling for artifacts caused by scaling, he demonstrated clear evidence of PE is the fossil record of some mollusc groups. And in Ontogeny and Phylogeny he more or less predicted the discoveries of evo-devo.


Yup.

Likewise Dawkins Gene-Centered approach undoubtedly paid dividends as well.


Yes, it was about emphasis, but I found that one quite powerful. By rephrasing things in terms of gene selection, it clarifies by other means what is muddled in the mind by being exposed to the idiot and handwaving group selection or the only vaguely hanging on kin selection. Even though, of course, there is no actual solid meaning of the word "gene," as approximate fictions go, it's pretty useful for brains. You can think in terms of counting them, and you can imaging them conferring survival benefits overall to a collections of individuals with them even if one or two have a really bad day. It makes sense.

And we are, after all, dealing with something that is hugely complex and random in practice and rather difficult for our little pea brains. There has to be some sort of simplification for grokkage purposes if there is to be any hope of insight. When looking for oversimplifications, at least maybe one can try to minimize idiocy. Dawkin's gene-based approach and his skill in explaining it did break a bottleneck of a bunch of biologists who previously were wandering around singing "Do dee do" and hitting each other with Nerf bats.

Mathematically and scientifically, it matters not a whit. Evolution is going to do what it does whether you like it or not, and you might as well get used to it, because it always wins by killing you anyway. Dawkin's advocacy clarified in a way that I think Gould's kinda didn't. From Dawkins I understand evolution better than I did. From Gould I understand more about sitting in a chair and getting others to run to the buffet and bring you food. From both there was a spectacular pissing contest until one died.

Probably the closest Gould came to saying something insightful was the talk about spandrels. This is sort of interesting and can inform modeling approaches. However, it's fairly minor. No, most of the beneficial forms probably aren't spandrels. The eye and all of it's intermediate forms probably were always about seeing, probably in all of the few score cases in which it evolved. Sure, it's an interesting and inspiring idea, but the 45 minutes or so he spent explaining it when I saw him in person, I could have been just as happy with a GameBoy or something. And there's always the risk of going too far in a minor direction.

But the extended synthesis takes care of all these issues, including epigenetics. :thumbup:


Yup again. Good stuff.
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Re: A Question about Evolutionary Theory

#14  Postby Spearthrower » Oct 28, 2014 3:33 am

One thing's for sure: their scuffles were positively Queensbury in comparison to the generational feuds in palaeontology and biological anthropology. I can imagine murder being done over the classification of a fibula.
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Re: A Question about Evolutionary Theory

#15  Postby epepke » Oct 28, 2014 4:30 am

Spearthrower wrote:One thing's for sure: their scuffles were positively Queensbury in comparison to the generational feuds in palaeontology and biological anthropology. I can imagine murder being done over the classification of a fibula.


And linguistics. But, yeah, during the 1980s you could hardly walk a quadrangle without being hit by a rock thrown by a cladist or a pheneticist.
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Re: A Question about Evolutionary Theory

#16  Postby Deremensis » Oct 28, 2014 5:51 am

epepke wrote:
Spearthrower wrote:One thing's for sure: their scuffles were positively Queensbury in comparison to the generational feuds in palaeontology and biological anthropology. I can imagine murder being done over the classification of a fibula.


And linguistics. But, yeah, during the 1980s you could hardly walk a quadrangle without being hit by a rock thrown by a cladist or a pheneticist.


I like to imagine a fantasy-esque "war of the academics"

Gray haired professors shuffling through the gates and clambering over the walls of universities, throwing textbooks, chalk, and writing utensils at one another while shouting incomprehensibly about one inpronounceable theory or another.
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Re: A Question about Evolutionary Theory

#17  Postby Darwinsbulldog » Oct 28, 2014 7:38 am

@ epepke:-

I actually think the conflict/discussions between Gould and Dawkins were productive. But I agree they were arguing on primarily a philosophical level. They trolled and straw-manned each others ideas, and I think often useful things fall out. Biology has had to put up with the more mathematical sciences, and this has biased the philosophy of biology. Although biology has caught up somewhat in having mathematical as well as verbal models, I do think that pluralism of opinion [yes, even the "woo" of the fuzzy-thinkers] has its place.
Even now we only have estimates of the numbers of species, and most are not formally described, never mind investigated in terms of their evolutionary biology, which is confined to relatively few species. [I recognize the pragmatism of that restriction of course]. So I think that plurality of theory in biology is not something that should worry people. The different "schools" will investigate different research programs and turn up different [often conflicting] evidence. For the foreseeable future at least, biology will tend to be messy in some respects. And because observation is in part theory-driven, there will always be theoretical conflicts because the different programs look at different things, or at least from different perspectives.
I think this is healthy. If evidence flowed easily and smoothly like from a regulated tap, then there might be less point to theoretical pluralism. But it does not, and so we get the upheavals as breakthroughs occur.
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Re: A Question about Evolutionary Theory

#18  Postby epepke » Oct 28, 2014 12:28 pm

Deremensis wrote:I like to imagine a fantasy-esque "war of the academics"

Gray haired professors shuffling through the gates and clambering over the walls of universities, throwing textbooks, chalk, and writing utensils at one another while shouting incomprehensibly about one inpronounceable theory or another.


Not bad at all. The rank-up system alone could be fascinating.
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Re: A Question about Evolutionary Theory

#19  Postby epepke » Oct 28, 2014 12:36 pm

Darwinsbulldog wrote:@ epepke:-

So I think that plurality of theory in biology is not something that should worry people. The different "schools" will investigate different research programs and turn up different [often conflicting] evidence. For the foreseeable future at least, biology will tend to be messy in some respects.


I agree; it's definitely good in general and certainly essential for all science. However, there comes a point where it gets counterproductive.

I'm much more of a cognitive science person than a biologist. In that field, I think it's pretty fair to say that the Linguistics Wars held things back for two or three decades. It's just now beginning to catch up. I'm only getting back into it again because it seems to have gotten advanced to the point that I thought it would have gotten to by 1990.

Now, Dawkins and Gould had a brouhaha that was mild by comparison. Neither was really powerful or obnoxious enough to put much of a damper on things, and it was easy to avoid. Still, it resonated.

I'm eternally grateful that Chomsky has gone into politics. Not that I usually agree with him; he says a lot of stupid things. But at least he says them in a field that naturally goes toward stupidity and which nobody seems to know how to fix. It keeps him off the streets and away from linguistics.
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Re: A Question about Evolutionary Theory

#20  Postby Spearthrower » Oct 28, 2014 2:09 pm

Deremensis wrote:
epepke wrote:
Spearthrower wrote:One thing's for sure: their scuffles were positively Queensbury in comparison to the generational feuds in palaeontology and biological anthropology. I can imagine murder being done over the classification of a fibula.


And linguistics. But, yeah, during the 1980s you could hardly walk a quadrangle without being hit by a rock thrown by a cladist or a pheneticist.


I like to imagine a fantasy-esque "war of the academics"

Gray haired professors shuffling through the gates and clambering over the walls of universities, throwing textbooks, chalk, and writing utensils at one another while shouting incomprehensibly about one inpronounceable theory or another.



What do you mean fantasy? :grin:
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