Talk:Punctuated equilibrium/2003 to June 2006

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Contents 1 Section on simulations 2 Links 3 "punctuated equilibria" vs. "punctuated equilibrium" 4 Ernst Mayr's understanding of punctuated equilibrium. 5 addes stuff about evidence 6 dawkins quotes that might be added 7 Alternative interpretations 8 Poor example in Alternative interpretations 9 Non-NPOV edits 10 Punctuated Equilibrium - God of gaps? 11 species substitution

[edit] Section on simulations

I have removed the following section:

==Simulations==

Recently, computer simulations have provided some insight into how punctuated evolution may work: The equilibrium periods show a gradual accumulation of neutral mutations, and the jump occurs when some beneficial combination of them reaches a certain threshold percentage.

While certainly interesting, the phenomenon demonstrated seems akin to saltation, not punctuated equilibrium. If this isn't so, then a better explanation is needed, as well as references.--Johnstone 02:43, 21 Dec 2004 (UTC)

[edit] Links

Why is an antievolution site being linked concerning PE? (Re: the ISCID Encyclopedia entry) That essay is inept in any case, failing even once to correctly label the alternative to PE as *phyletic* gradualism. If it is being retained as an example of the hash that antievolutionists make of the concept, that should be indicated in the description of the link. --Wesley R. Elsberry

[edit] "punctuated equilibria" vs. "punctuated equilibrium"

I moved this back because:

1. It is not inline with the naming conventions (don't use plurals).
2. Punctuated equilibrium gets more Google hits (70,000) than Punctuated equilibria (52,000)
3. It is widely taught in evolutionary biology courses using the singular form.

--Lexor|Talk 13:58, Dec 31, 2004 (UTC)

Reply:

1. This isn't a valid application of the rule for article titles. While "punctuated equilibria" is plural in grammatical construction, it is singular in concept. Think Great Lakes, New York Yankees, or Federalist Papers.
2. If it was a complete misnomer (but it's not, see item 3), the number of Google hits wouldn't matter. It would still be wrong to use it. For example, if a majority of people thought that "nucular power" was correct, should that term be used for the article nuclear power?
3. Gould originally used "equilibria", and continued to use it for several years, but appears to have switched over to "equilibrium". He may have bowed to popular usage: people are much more familiar with the word "equilibrium," and possibly mistakenly used it rather than the correct "equilibria." I seem to remember reading something once where he discussed this issue, but haven't been able to find it using Google. Anyone? If more definite information on this can be found, it should be reflected in the article. Other biologists (including Mayr) continue to use "equilibria." Not that it matters for the sake of the article content (i.e., if an inaccurate term is the generally accepted term, then so be it), but to me, "punctuated equilibrium" seems to be an oxymoron per the theory: When an equilibrium is punctuated, it returns to a different equilibrium, so it's at least two equilibria.

--Johnstone 23:38, 3 Jan 2005 (UTC)

I'm not saying Google is the ultimate arbiter, but basically both are correct, and while punctuated equilibria as you point out is probably more technically correct, punctuated equilibrium is also correct (and certainly not incorrect, so we are not in the situation where we are propagating an incorrect title). However, I maintain that since punctuated equilibrium is widely accepted (even by Gould towards the end of his life) and widely introduced under that title in textbooks, and it wins the "popularity contest" that that should trump the minor extra amount of technical correctness. --Lexor|Talk 11:34, Jan 4, 2005 (UTC)

Agreed. I wasn't arguing against "equilibrium," just making a few comments. Your reverting the article to "equilibrium" was the right move. (Again, this whole topic of the two names should to be reflected in the article, once comments by Gould about the usage of "equilibrium" are found.)--Johnstone 01:36, 5 Jan 2005 (UTC)

But is there some change that could be made anyway? I found the name 'punctuated equilibrium' to be confusing; I didn't know what it meant. At best, it was a short, sharp equilibrium between two times of change: But apart from being nonsense, that's the complete opposite of what's meant. Punctuated equilibria, OTOH, makes sense. We should make sense and be correct. A redirect can take people who are popular to the sensible one. Felix the Cassowary 08:15, 20 Feb 2005 (UTC)

( (The "two times of change", equilibrium before, equilibrium after, is ignoring this: The two things occurring are —(little short events of Punct. equil. are adding up to what appears to be just "One", geologic-time-scale--"Punctuated equilibrium point" ): 1--the speciation changes(they are actually just a 'pressure', because they have to sustain long enough to go(spread) through the population, (as Darwin knew) ), 2--and the change in the External environment; the "time elapsed" may have the ext. environment change, then change back to original, or all sorts of variations of this theme; But the two events changing are the " Internal Speciation ", and the " External environment ", which if nothing really changes (in the external), then at least: time has passed, (rain has fallen, geology has changed, the continents have moved a little, all data facts) ) ).6.3.55.1 18:26, 1 December 2005 (UTC)

( (It is fine to discuss this "plurality" dilemma; However, If one has read Darwin, seen the various "sub-components" of Evolution, 1—the Cosmic catastrophe events, 2— the astronomical 3-cycle systems (that eventually line up full-axis tilt, orbital variation, and the 3rd (?)(these have the Ice age,Glaciation implications) ), 1B—the Impacts that cause a chemical change in the ocean-continent system, 3—the continental drift, tectonic event that causes an ocean gyre to be removed, globally, (a Paleoclimatology problem), 4— the huge "array" of speciation, or inter-speciation events going on,... all just a list of "Changes globally", or 'almost' globally,...however, if one doesn't understand, the creation of a " New term ", specifically "Punctuated equilibrium", covers the same ideas talked about, even before Darwin (the Ocean explorers, observed some of this)(the Greek-Darwin, others?). So, the creation of "new terms" are an attempt to incorporate more data into the equation. If one cannot guess that Punctuated equilibrium/bria concerns Evolution, then it is also like saying: "How does Cladistics help understand speciation?" Cladistics-study, of an organism(within a species), looking internally (and functionally) inside of a species, and sees parts of the body. The "family trees" are perfected, elucidated through "cladistics". But this was noticed in the 1800's and earlier, by the term "convergent evolution" (As in the dolphin is shaped like the Fossil "Ichthyosaur"). Cladistics is just more precise, technical, and from one bone shape/function, the door of knowledge is opened. ...So, if one cannot guess what the Law of superposition, or the Law of faunal succession refers to, better to send the 'students' into another line of study. In Bold, or Highlight: Evolution is a study of 'Knowledge'; Evolution is not a study of Truth. [ Another term that is possibly unknown, is that after the "Impact", the "Catastrophe", ...there are the [Sweepstake winners (biology)] (could be made into a wiki study (if not already)); our Human species is part of the Winners group, incidentally. ] ) ) 6.3.55.1 18:26, 1 December 2005 (UTC)

Although the singular form is pretty common, I agree with Felix that the plural form is to be preferred. --Wesley R. Elsberry

"Equilibria" sounds weird; after all, we don't speak of quanta theory, strings theory, computers science, plants protection, etc. --isidora 06:23, 13 October 2005 (UTC)

[edit] Ernst Mayr's understanding of punctuated equilibrium.

The article, at the time of my writing, says: "Punctuated equilibrium is often confused with quantum evolution, saltationism, catastrophism, and with the phenomenon of mass extinction, and is therefore mistakenly thought to oppose the concept of gradualism."

It might be noteworthy to add that Mayr in his book "The Growth of Biological Thought : Diversity, Evolution, and Inheritance" (1982), notes that he believes Gould & Eldredge theory is more accurately described as saltationism than his own, which he considers different. While he might have changed his views, it is hard to forget this comment. --Thomi 02:16, 23 March 2006 (UTC)

If you read Mayr more carfuly (which I had to do many times) he actually considers it both gradual and saltational—all in in the same breath! First as a gradual account, when it properly employs his mode of peripatric and allopatric speciation. And then in the saltational mode, which Mayr (wrongly) interpreted from a poor reading of Gould's Natural History essay "The Return of Hopeful Monsters." For his proof Mayr quotes Gould as saying "Macroevolution proceeds by the rare success of these hopeful monsters, not by an accumulation of small changes within populations." But if you look at the essay it is as clear as day that Gould was articulating Goldschmidt's views, not his own. Furthermore this paper was never related—directly or indirectly—to punctuated equlibrium, but rather, as an attempt to open theoretical space to the idea, long disposed, that "small changes early in embryology accumulate through growth to yield profound differences among adults." Gould did play with a moderate form of saltationism, but not in the essay Mayr quotes. This is to be found in the 1980 paper listed in the bibliography. But as before, it had nothing to do with punctuated equilibrium. Best, Miguel Chavez 18:04, 8 June 2006 (UTC)

And you're right, he has since changed his views. Best, Miguel Chavez 18:14, 8 June 2006 (UTC)

[edit] addes stuff about evidence

hi guys!

i added a bit about evidence, this stuff is well proven and it would be a shame if it did not reflect on the article besides from the mechainsm i mentioned there are anothers (at least one that i dont remember right now)

bye!

(sorry for my poor english)

I think that the bit you added, is not quite about PE, i.e., stasis and periods of quicker evolution, but rather about genetic and developmental mechanisms for quick evolution, which are not part of PE per se, even though they can be. But are not more PE than phyletic gradualism or punctuated gradualism, never the less. --Extremophile 00:53, 14 May 2006 (UTC)

[edit] dawkins quotes that might be added

I think that the mentioned opposition of Dawkins is problematic area. I do not think that he has a problem with punctuated equilibrium, but more with the way it used to be divulged:

• What needs to be said now, loud and clear, is the truth: that the theory of punctuated equilibrium lies firmly within the neo-Darwinian synthesis. It always did. It will take time to undo the damage wrought by overblown rhetoric, but it will be undone. [251]"

• ... it is all too easy to confuse gradualism (the belief, held by modern punctuationists as well as Darwin, that there are no sudden leaps between one generation and the next) with 'constant evolutionary speedism' (opposed by punctuationists and allegedly, though not actually, held by Darwin). They are not the same thing at all. [242-243]

From the "Blind Watchmaker" book http://www.simonyi.ox.ac.uk/dawkins/WorldOfDawkins-archive/Dawkins/Work/Books/blind.shtml

--Extremophile 16:25, 5 June 2006 (UTC)

[edit] Alternative interpretations

Please do not impose a particular view of punctuated equilibrium on this article when the newer scientific literature supports alternatives. Wikipedia articles are supposed to have an NPOV.--StN 02:36, 6 June 2006 (UTC)

I don't disagree with you changing the section header, but I'm not sure what you mean with the above. There are all sorts of alternatives to Punctuated Equilibrium, it is only one amongst numerous macroevolutionary theories. On the other hand, the only 'particular view' that really matters is that of E+G, as put forward in their original paper with subsequent papers by them clarifying and expanding their original intent, and perhaps that of their supporters who add evidence or further clarification within the avowed framework of PE. I'm not sure if one can have an alternative view of a particular scientific theory; one either believes that it's true or that it is not. A better word for 'an alternative view' would be 'a new theory', i.e. Einstein had an alternative view of the workings of gravity to Newton. Badgerpatrol 03:01, 6 June 2006 (UTC)

"Alternative interpretations," in this context, is meant to indicate that "PE is a form of gradualism" is not the only way of understanding how the pattern discerned by E+G arose. There are other possibilities, as I have indicated in the additions. So this is not an alternative to PE, but an alternative to the assumption that everything in evolution has to be gradualistic, even when it doesn't look that way.--StN 03:11, 6 June 2006 (UTC)

[edit] Poor example in Alternative interpretations

The example ends with the sentence: "It is therefore reasonable to conclude that if the limb size in our hypothetical population evolved in the most conservative manner, it need only increase at a rate of 0.005 cm per generation (= 50 cm/10,000), despite its abrupt appearance in the geological record."

I find it incredible that anyone would take such an explanation seriously. So called "random" mutations of the same type must occur 10,000 times in a row. Not only that, natural selection must act on a variation in length that is about the size of a bacterium. This is not science. Please remove that example and give one that is as least a believable explanation of a possible mechanism for PE. OFG 03:20, 8 June 2006 (UTC)

I think you're misreading the example. Its point is that even tiny changes generation to generation can still amount to apparently instantaneous change in the fossil record, let alone selection operating on much larger differences (which would appear even more instantaneous; were that possible). It's not meant to be read absolutely literally, it's hypothetical. This isn't to say that it's not possible; differences only need to confer advantage on a statistical basis for them to be selected and lead to longer term change. The magnitude of an "advantage" depends on lots of factors (including things like population size; whether a species is r/K selected, etc.), many of which are difficult for an external observer to quantitatively discern.

Regarding PE, the point this example is making is simply that apparent "jumps" in the fossil record can simply be caused by steady selection - PE might not be happening at all. So this isn't an example of PE at all (which instead would suggest that something "interesting" has been happening on top of steady selection). Does this help? Cheers, --Plumbago 10:03, 8 June 2006 (UTC)

Yes, it isn't an example of PE and doesn't really seem to me to be relevent. Obviously, it is oversimplified (no reversals, constant incremental non-adaptive change, makes a mockery of population genetics and intra-population variation etc etc) but that is perhaps reasonable in a teaching example. But surely the key point it is missing is that the reason the effect will be observed as saltational rather than gradual is because of time averaging the poor resolution of the fossil record. To my mind, this is the opposite intent to that of PE, which (effectively) posits that there is actually not too much wrong with the fossil record as an index of evolutionary trends, and the staccato pattern of evolution observed is actually faithfully relating a genuine underlying process. The example given doesn't to my mind explain anything useful about PE at all. Badgerpatrol 12:40, 8 June 2006 (UTC)

I disagree. It's just making a very simple point that is entirely pertinent to PE, but not an example of it. All that is being said is that even very gradual change can stack up sufficiently that it looks like a PE event in the fossil record. Although it's hypothetical, it serves to underscore that boring old gradual change can be responsible for an impressive "jump" in fossil history rather than positing a special mechanism, like PE, to "speed up" evolution. I believe the idea was originally suggest by Stebbins (1982) then re-used (spun to address PE) by Dawkins (1986) in The Blind Watchmaker. Cheers, --Plumbago 13:17, 8 June 2006 (UTC)

It says nothing about PE because it doesn't mention why such change would appear to be sudden in the fossil record, i.e. because there are naturally large temporal jumps between horizons due to incompleteness. There is no context. Whilst this might be obvious to a palaeontologist, it is not explicitly layed out for an interested untrained reader. All it is currently is a rather oversimplified (misleading?) example of simple gradualism. There is a problem here discriminating data (=the fossil record of an organism often seems to be made up of large and sudden morphological jumps) and the interpretative theory (=punctuated equilibrium). The idea that deficiencies in the fossil record are causing large macroevolutionary jumps to be perceived when the actual underlying process is gradualistic pre-dates 1982 by a long way; it has been floating around since Chuck Darwin at least. Badgerpatrol 13:34, 8 June 2006 (UTC)

You're right about the clarity of the explanation. The article (at best) only implies the connection between the short timescales and fossil record incompleteness. It would certainly help to have this made more explicit. If this is added, I think the example makes more sense. Regarding the age of the idea, yes, you're correct of course, it isn't new. I should have said that the specific example of animal/limb size is one used by Stebbins (and repeated by Dawkins in a discussion of PE). Anyway, with these qualifications, I think the example could remain, but if you can think of a better way to rewrite this objection to PE that might be best. Actually, re-reading the paragraph, I find the earlier portion, "... though evolutionary change aggregates "quickly" between geological sediments ...", even more opaque. So perhaps a complete rewrite is in order? Cheers, --Plumbago 16:18, 8 June 2006 (UTC)

No, it doesn't have to happen a 10,000 times in a row, in a progressive manner. I believe that you are picturing evolution from one generation to the next, to the next, to the next, and so on. Evolution doesn't work that way. Evolution takes genes from the entire population and sorts them through natural selection and other mechanisms. Natural selection has an entire pool of genetic variation to work from. Populations evolve, not individuals, and not single lines of generations. But this is a very common misunderstanding. Lastly, Badgerpatrol has questioned the general usefulness of this paragraph. And I have questioned it too, but I agree with Plumbago that it helps by eliminating some of the confusion that PE relies on some sort of "alternative" mechanism. It doesn't. As anyone remotely familiar with the literature knows, it never has. (For those in the know, but who would question this, Gould's 1977 and 1980 papers were not about PE). I think who ever wrote it got the idea from Dawkins chapter in The Blind Watchmaker, which makes a similar argument. --Miguel Chavez 17:18, 8 June 2006 (UTC)

I understand quite well how evolution is supposed to work. I understand the capriciousness and contingencies in the workings of evolution. It is the paragraph in question, especially the example in that paragraph, which distorts the workings of evolution. The phrase “it need only increase at a rate of 0.005 cm per generation (= 50 cm/10,000)” easily gives the impression of progressive linear change. The anthropocentric notions of directionality and purpose often (I assume inadvertently) find their way into the writings of specialists who attempt to explain various forms of Darwinian evolution. From these I have often read how evolution “invents” various forms and functions. Carl Sagan, in my opinion one of the worst offenders in these matters, injected anthropocentric notions on a massive scale so as to justify his idea of a million highly advanced technological civilizations in the Galaxy. I read your paragraph as suffering from the same notions of directionality. --OFG 15:35, 9 June 2006 (UTC)

I see how it can be read that way, but when evolutionists speak of generations, they are speaking from the point of view of the population, not the individual. It's not the paragraphs fault, it's simply the only word we have. (And it is not my paragraph, but I think it has been somewhat helpful.) If you believe you can improve upon it, please, by all means, do. Best, Miguel Chavez 16:22, 9 June 2006 (UTC)

About the example, why do not substitute for something more real rather than something purely abstract and problematic? For example, the Grant's sudies with Finches had shown that three species of the genus Geospiza will evolve gradually in a few generations, as they witnessed; but at the same time, island conditions and short lifespan of the birds made impossible to the graduality of this evolution to be recorded in fossil. However, despite of not leaving the impression that what is happening is a fictitious hypergradual orthogenetic evolution, it still not is a example of PE, but I think it still is needed to explain how PE can be gradual.

Other idea I think that might be good would be a explanatory table or simple scheme of some kind, with the real oppositions and short explanations... "phyletic gradualism" vs "punctuated equilibrium" (maybe with punctuated gradualism in between) and "gradualism" vs "saltationism" --Extremophile 03:42, 18 June 2006 (UTC)

As I think I mentioned above, a distinction should be made between theory and observation. Punctuated equilibrium is a theory to describe the (disputed) observation that new species tend to occur suddenly in the geological record. Any example (and forgive me if I'm misreading what you are trying to say) that seeks to posit the idea that this observation may be an artefact of incomplete preservation of gradually evolving species is by definition an alternative to PE, not an example of it. Badgerpatrol 03:50, 18 June 2006 (UTC)

I was referring to the example "It is therefore reasonable to conclude that if the limb size in our hypothetical population evolved in the most conservative manner, it need only increase at a rate of 0.005 cm per generation (= 50 cm/10,000), despite its abrupt appearance in the geological record.". Which attempts to make clear that although a new species can occur suddenly in the fossil record, it does not necessarely indicates saltation. Since this example has some problems, as discussed above, I suggested a real occurrence of how evolution can be quick without these problems. Just happens that this specific case is also an example of how something could evolve in a non-PE way and yet would more likely look as if it were in the fossil record, but what causes this evolution to be quick can occur in a PE instance too, by no means implies that there is no PE at all. --Extremophile 20:21, 18 June 2006 (UTC)

[edit] Non-NPOV edits

Punctuated equilibrium describes the tempo and mode of evoluionary change as determined from the paleontological record. It implies nothing about the underlying mechanism for this or whether the "jumps" are apparent or real. Gould took a more saltationist position early in his career but eventually went over to the gradualist side. The purpose of this article is not to track SJG's intellectual peregrinations, but to explore the content, history, and scientific reception of the PE concept. Shifting the neo-saltationist interpretations arising from some recent EvoDevo work to a separate article is to sweep thes ideas under the rug so as leave this article comfortably within the neo-Darwinian paradigm. If the editors who keep removing the EvoDevo/tissue morphodynamics material cannot come up with a good justification for doing so over the next few days I will replace it. If they continue to remove it without good reason I will seek to have a non-neutrality advisory tag placed on the article.--StN 17:13, 8 June 2006 (UTC)

I'm sorry, but you're mistaken. Punctuated equilibrium is a specific theory of how cladogenesis—in particular peripatric and allopatric speciation—aggregates itself in the geological record. It is not a universal theory of rapid evolutionary change. And it's not proper to employ any mechanism of your liking as a substitute for the one outlined in their original 1972 paper, and subsequent papers. Eldredge and Gould have publicly complained about this numerous times, and a careful reading of their papers agrees with this interpretation. I moved your contributions elsewhere because if we keep it here it will continue to misinform people about what punctuated equilibrium is trying to say about the nature of the paleontological data and evolutionary theory. I don't want to short-shrift your contributions, but I have to protect the integrity of the article above all else. If people are going to make changes, they have to know what they're talking about. For example someone wrote that Hugh Falconer anticipated Mayr, Eldredge and Gould, but Falconer ideas were related to the tempo of evolution and had absolutely nothing to do with peripatric and allopatric speciation. Stasis is as old as paleontology. Best, Miguel Chavez 17:49, 8 June 2006 (UTC)

I appreciate your explaining your rationale, and will defer to your views for the time being, since you have clearly invested a lot in this article. However, my reading of the the original PE papers is a bit different. Gould was one of the major initiators of the contemporary EvoDevo field, particularly with his book "Ontogeny and Phylogeny," which discussed the evolutionary effects of the reorganization of body plans. Mechanisms such as neoteny and paedomorphosis can lead to extensive correlated morphological change with little genetic change. When considered in this context, the discussion on p. 114 of the 1972 Eldredge and Gould paper on the role of individual developmental homeostasis in maintaining species identity supports my view. In particular, the breach of developmental homeostasis (e.g., by the developmental alterations described in O&P and by the morphodynamic mechanisms I referred to in my original contribution) is precisely a mechanism of allopatric speciation. I think in your assertion that PE is a specific theory of cladogenesis, based on ideas like allopatric speciation, you are neglecting the fact that allopatric speciation is actually a descriptive phenomenon that itself *requires* a mechanism.

One more thing: if the idea that PE opposes the concept of phyletic gradualism is a "common misconception," as the article currently states, and if PE is actually a form of gradualism, then why is the 1972 article titled "Punctuated Equilibria: An Alternative to Phyletic Gradualism"?--StN 18:56, 8 June 2006 (UTC)

I see where you're coming from, but I still disagree. Re-reading the original Eldredge and Gould paper I find that their use of development is tied specifically to the morphological stability of species (i.e. stasis), not to rapid evolution caused by key mutations affecting development and timing (the punctuations). As for allopatric speciation, this is still caused by standard population dynamics, namely reproductive barriers, population size, the "alien [peripheral] environment," and natural selection. What Eldredge and Gould are saying here is that these mechanisms are fighting against more than simple gene flow (as Mayr and others assume), but developmental homeostasis as well (as suggested by Lerner and Ehrlich and Raven). On this reading, however, I would recommend that we include this aspect into the article to reflect that there be more to stasis than gene flow.

Lastly there are two kinds of gradualism: phyletic gradualism (the slow transformation of whole lineages through the succession of geological time) and populational gradualism (that genetic change from one generation to the next is incremental). Eldredge and Gould were speaking of the former. See Ernst Mayr's One Long Argument or his "Speciational Evolution or Punctuated Equilibria" for further detail and elaboration. Best, Miguel Chavez 19:09, 8 June 2006 (UTC)

Here's what I got from a quick search of Gould's texts. Hope this helps.

• "In this crucial sense, the theory of punctuated equilibrium adopts a very conservative position. The theory asserts no novel claim about modes or mechanisms of speciation; punctuated equilibrium merely takes a standard microevolutionary model and elucidates its expected expression when properly scaled into geological time. S. J. Gould The Structure of Evolutionary Theory. Cambridge MA: Harvard University Press. 2002. p. 778.

• "Ordinary speciation remains fully adequate to explain the causes and phenomenology of punctuation." ibid. p. 1001.

• "I did speak extensively—often quite critically—about the reviled work of Richard Goldschmidt, particularly about aspects of his thought that might merit a rehearing. This material has often been confused with punctuated equlibrium by people who miss the crucial issue of scaling, and therefore regard all statements about rapidity at any level as necessarily unitary, and necessarily flowing from punctuated equilibrium. In fact, as the long treatment in Chapter 5 of this book should make clear, my interest in Goldschmidt resides in issues bearing little relationship with punctuated equilibrium, but invested instead in developmental questions that prompted my first book, Ontogeny and Phylogeny. The two subjects, after all, are quite separate, and rooted in different scales of rapidity—hopeful monsters in genuine saltation, and punctuated equilibrium in macroevolutionary puntuation (produced by ordinary allopatric speciation)." ibid. p. 1005.

• "Finally, the claim that we equated punctuated equilibrium with saltation makes no sense within the logical structure of our theory—so, unless we are fools, how could we ever have asserted such a proposition? Our theory holds, as a defining statement, that ordinary allopatric speciation, unfolding gradually at microevolutionary scales, translates to punctuation in geological time." ibid. p. 1009[1]

• "Punctuated equilibrium is not a theory of macromutation…it is not a theory of any genetic process…It is a theory about larger-scale patterns—the geometry of speciation in geological time. As with ecologically rapid modes of speciation, punctuated equilibrium welcomes macromutation as a source for the initiation of species: the faster the better. But punctuated equilibrium clearly does not require or imply macromutation, since it was formulated as the expected geological consequence of Mayrian allopatry." S. J. Gould, "The meaning of punctuated equilibrium and its role in validating a hierarchical approach to macroevolution." In R. Milkman, ed., Perspectives on Evolution. Sunderland MA: Sinauer Associates, 1982. p. 83.

• "Punctuated equilibrium is a specific claim about speciation and its deployment in geological time; it should not be used as a synonym for any theory of rapid evolutionary change at any scale . . . Punctuated equilibrium holds that accumulated speciation is the root of most major evolutionary change, and that what we have called anagenesis is usually no more than repeated cladogenesis (branching) filtered through the net of differential success at the species level." ibid. 84-85.

• "First, simple misunderstanding of basic content was distressingly common, even among professional evolutionists. Many colleagues thought that we had raised the old anti-Darwinian specter of macromutationism, or truly sudden speciation in a single generation by a large and incredibly lucky mutation. I do not know why this happened; I think that all our articles and public statements were clear in separating human from geological rapidity." S. J. Gould "Opus 200" Natural History 100 (August 1991): 16.

• "Punctuated equilibrium was not a grandiose theory of the nature of change, a Marxist plot, a cladistical cabal, an attempt to sneak the hopeful monster back into evolution, or a tortuous assault on the concept of adaptation. It was at first, and has always been: (1) A well-defined, testable theory about the origin of species and their geological deployment (not a general rubric for any old idea about rapidity at any scale, and specifically not a notion about saltation, the origin of new Baupläne, or mass extinction). (2) A theory based on the recognition that events judged as glacially slow in ecological time might appear instantaneous in geological resolution (the conversion of the peripheral isolate into species, in particular). Some neontologists, misconstruing punctuated equilibrium as a theory of saltation, have charged that we made a disabling error in not recognizing the difference in scale between ecology and geology and in thinking that geological abruptness demanded some notion of true discontinuity. Quite the reverse: Punctuated equilibrium is not a theory of saltation, and its anchor lies in this appreciation of scaling—particularly, in recognizing how an ecological "slow" event like allopatric speciation must translate into the geological record." S. J. Gould "Punctuated equilibrium in fact and theory." In Albert Somit and Steven Peterson, The Dynamics of Evolution. New York: Cornell University Press, p. 57.

— Miguel Chavez 21:15, 10 June 2006 (UTC)

I never claimed (in my original addition to the article, which you removed) that punctuated equilibrium was equivalent to saltationism. I said it was consistent with, and possibly explained by, saltationism. That is, I changed the section title from Common Misconceptions to Alternative Interpretations, so as to make the point that although there are gradualist interpretations of PE, there are also saltationist ones, and modern EvoDevo provides a basis for them. As you quote Gould as saying in 1982: "As with ecologically rapid modes of speciation, punctuated equilibrium welcomes macromutation as a source for the initiation of species: the faster the better." It couldn't be clearer that the original conception of PE was consistent with rapid morphological change. That it does not require saltation is irrelevant. I did not claim it did. I just presented it as an alternative interpretation (without removing the gradualist one, by the way). This brings a more neutral point of view to the article. If you insist on calling the possible saltationist interpretation of PE a common misconception (one that Gould held in 1982), then this undermines the usefulness of the article. The fact that Gould threw in the towel on this in his later writings is also irrelevant. He did not keep up with the recent developments in EvoDevo toward the end of his life and was unable to defend rapid evolution scenarios (which he was clearly attracted to, continually revisiting Goldschmidt, D'Arcy Thompson - more than 30 pages in his final book - and even Lamarck) against his neo-Darwinist critics. But recent findings provide developmental mechanisms for rapid evolution, and Gould's original instincts were on target.--StN 05:20, 11 June 2006 (UTC)

Of course you are right—saltation is consistent with punctuated equilibrium. After all, how could it be otherwise? And I know you didn't make the obvious error in saying that punctuated equilibrium equates with, or even suggest, saltation. That was never my issue. However, as Gould rightly emphasizes, the issue of special developmental mechanisms involved in rapid (or instantaneous) speciation is a completely separate theoretical problem (and one that cannot be resolved by a careful analysis of the fossil record). And here we have the fundamental issue. Punctuated equilibrium takes a specific account of speciation—one that is (for the better part) standard, conventional, and well studied—and extrapolates it through the immensity of geological time. In a nutshell, punctuated equilibrium is the geological rendering of Mayrian cladogenesis. If anything, Eldredge and Gould have been meticulously steadfast in limiting their theory to this strict and testable mode. There is no alternative interpretation to be made, so therefore no metaphorical towel to be thrown. Other mechanisms, even conventional ones (such as habitat-tracking), may reproduce patterns of geological stability and rapid displacement, but they are supplemental theories, not subsidiary mechanisms in some grand overextended theory of punctuational change. Punctuated equilibrium does not subsume all theories of evolutionary rapidity, as the many quotations I've given, I think, make clear. And lastly, I don't want you to think that I'm hostile to your ideas, or your contributions. In fact, I feel strongly sympathetic. All I ask is that we respect the proper boundaries of an idea. Words have meaning. And robust scientific theories must be strict in their scope, and must be well defined. Punctuated equilibrium has more than just a few times been criticized for being a "moving target." And from my reading, I don't think this criticism has been at all fair. And I don't want to play into it. If people have trouble understanding punctuated equilibrium, it is because they have not read carefully, or misunderstood the problems punctuated equilibrium was intended to solve. I am willing to give an inch however, and will be happy to re-include your contributions myself, so long as it's made clear that these are not a part of punctuated equilibrium, but are consistent with the general pattern. Although, if not explained well enough, it may be misleading. (Perhaps I moved to quick to remove the text, rather than to take the time to rework it.) Miguel Chavez 06:05, 12 June 2006 (UTC)

I think this is a very fair assessment and proposal. I will leave it to you to work in a version of the text I supplied in a way you consider appropriate to the article.--StN 15:00, 12 June 2006 (UTC)

[edit] Punctuated Equilibrium - God of gaps?

How is this theory really a science? It's really hard to accept it as science, if this is what science is all about:

  1. Make observations.
  2. Form a testable, unifying hypothesis to explain these observations.
  3. Deduce predictions from the hypothesis.
  4. Search for confirmations of the predictions;
     if the predictions are contradicted by empirical observation, go back to step (2).

TalkOrigins. It seems like it's a poor exuse to fill in the gaps for unexplained theory of transitional steps of macroevolution. This is pure hypocrisy due to the fact that most deniers of creation, trying to poke fun of ID (intelligent design), say that ID theory is based on a belief in this so called God of Gaps (who is a supernatural being). Well, punctuated equilibrium theory is one strong claim, however without any evidence to back it up? (or to be more scientific, why don't we observe this happen today), so we can predict it as having occured in the past? And please don't use such statements as "it must have happened, therefore it did".Lyotchyk 10:47, 27 June 2006 (UTC)

• Quickly, because wikipedia is not a discussion forum. Punk eek predicts that there would be longer periods of relatively stasis, punctuated with relatively quicker episodes of evolution ocurring in small populations. It is consistent with populational genetics (see for example, hardy-weinberg equilibrium and founder effect). It does not claim that the evidence is lack of transitionals between species. It says that those will be less likely to found, and, when those are found, they will be in shorter distributions in space and time, rather than the whole species, over all their territorial distribution, gradually changing over time. There are findings that go according with this, I think that in the very talk origins website there is a section on PE. Besides all that, it does not proposes to fill major gaps on macroevolution, in the same way ID proponents say that ID tryes to; the more important evolutionary change is still driven by natural selection, and do not occur in single episodes of macroevolution (I.e, speciation), but gradually across a longer phyletic distance. Speciation itself is not such a big deal. Most of the difference between closely related species is not different from the type of difference found between dog breeds, plus gradual degrees of sterility and inviability (sometimes can be less gradual). Gould himself pointed a few times, that there are plenty of transitional forms between higher taxa, which are much more relevant than transitional forms between species. Now, I suggest that if there is yet anything you want to discuss, to do it in a discussion forum, such as EvC forums, SciForums.com, or even at Talk.origins --Extremophile 05:04, 28 June 2006 (UTC)

[edit] species substitution

I'm not an expert but I think that species substitution has much to do with TE, like being almost half of it, doesn't it? But the article doesn't even mentions it. --Extremophile 00:58, 12 August 2006 (UTC)