Talk:Saltation (biology)

Out of date
I am new to wikipedia and would like to explore updating this page. I don't want to just start doing it, but have noticed it is grossly out-of-date when it comes to the idea of "saltation" as it is being dicussed within biology. My passion is the history of science with a focus on biology, and for anyone who knows the history of biology, this page really needs to be updated. Is anyone interested in examining some of this historical information and how it might be used to update this page? Dogyo (talk) 18:32, 4 February 2009 (UTC) Dogyo


 * Some related material may be found in a series of blogs by evolutionary biologist Arlin Stoltzfus, at very least indirect pointing to other sources, more appropriate to an encyclopedia than a blog:
 * https://www.molevol.org/cdblog/mutationism_myth1
 * It's an interesting presentation on this chapter of history of evolutionary biology, contrasting with the more common takes on it, often analogues to the over simplistic/distorted "Mendelian Darwin" opposing Lamarck. Although that's more specific to "muationism" than "saltationism," although there may be some kind of gray area, or overlaps. If I recall, "saltationism," while sometimes speaking of "macromuatitions," refers more to large phenotypical changes, regardless of how big would be a mutation. But natural selection is left more or less untouched, only an "omnigradualism" is challenged, although it seems some of its proponents were bolder and somehow imagined natural selection as less relevant even in challenging the "hope" of the monsters, however self-contradictory that may be. Well, "mutationism" also doesn't touch in mutation size AFAIR, but rather that mutation itself or bias in mutations would be a more significant evolutionary "forcing," from just creating more random minute variation that hinders the population from reaching the "perfect" outcome of natural selection, to something more stronger, like an weak version of "orthogenic evolution" (in the sense related to ideas of evolution improving adaptation almost magically, inherently, inexplicably, vs the more mundane notion of "orthogenic sequences" in the fossil record, where a gradual kind of "progress"/"evolution" can be clearly seen, like horse from Eohyppus, as the classic example, if I recall). Like some viruses always ending up with certain mutations almost regardless of natural selection, because the biochemistry dices are loaded. 45.234.133.177 (talk) 04:12, 14 October 2023 (UTC)

History
Saltationism is more modern than Lamarkism, but less modern than Sputnik. It's all well and good that one person was named as supporting this antique theory, but the article does a disservice to the encyclopedia and anybody who reads it in hopes of learning. This page desperately needs to reflect the contemporary knowledge humans have managed to acquire. —Preceding unsigned comment added by 207.138.32.33 (talk) 21:51, 4 February 2009 (UTC)

To refer to saltation as an "antique theory" is in itself ahistorical and misleading. There currently exists a large amount of information from scientific sources, especially starting from 1975 on when evolutionary developmental biology became an independent field. Take for just one example, Stephen J. Gould's (2002) final work "The Structure of Evolutionary Theory" (SET). In this work he basically argues that due to the new evidence forthcoming from Evolutionary Developmental Biology that some of the long held beliefs with the Neo-Darwinian Modern Synthesis are in need of reevaluation. With the rise of the Modern Synthesis, which Gould himself notes was more a constriction in that it black-boxed and excluded such areas of research as development, phenotypic plasticity, etc., it became almost a dogma that evolution proceeded along gradualist lines with no real so-called “saltations.” This concept was considered in a far wider context than just De Vries “Mutation Theory,” being a concept that was discussed within the larger context of “Problem of Continuous vesus Discrete Variation and Change” (West-Eberhard, Mary Jane. Developmental Plasticity and Evolution. Oxford: Oxford University Press; 2003; p. 11.)

Gould was one of those who started the entire discussion around the re-synthesis of evolutionary theory to include development with his work “Ontogeny and Phylogeny.” He made his final argument for the need to reevaluate current evolutionary theory in light of the discoveries of Evo-Devo in his SET. Gould, in one section titled “Does evolutionary change often proceed by saltation down channels of historical constraint?” states the following:

"[I]nternally channeled evolution (orthogenesis) has been intimately linked with discontinuous change (saltationism) in the history of structuralist thought (with the model of “Galton’s polyhedron” serving as the classical image for the connection). The linkage isn’t physically necessary or logically impelled, for some orthogeneticists have favored gradualism (C. O. Whitman, pp. 383-395), whereas some saltationists have rejected internal directionality (Hugo de Vries, pp. 415-451).  But in expanding the causes of evolutionary change beyond the incremental gradualism of externally directed Darwinian selection, and in regarding internal channels of developmental constraint as important mediators of phyletic trending, most advocates of formalist or stucturalist explanation (Bateson, D’Arcy Thompson, and Goldschmidt, for example) have supported some linkage of channeled directionality with at least the possibility of saltational movement down the channels -- of only because the potential phyletic analog of such ontogenetic phenomena as metamorphosis seems intriguing and worth exploration. (Gould 2002: 1142)

"Thus, with the reintroduction of internal channeling by historical constraint (based on genetic homology) into our explanatory schemes, we must ask whether saltational themes (that had been even more firmly rejected by the Darwinian Synthesis) can also advance a strong case for a rehearing. My own conclusions are primarily negative (hence my parsing of this theme as a scherzo, and as the shortest movement of my analysis), but the subject clearly merits some airing (and undoubtedly holds limited validity), if only as a sign of respect for the intuition of so many fine evolutionists, throughout the history of our subject, that structural channeling -- now clearly affirmed as a theme of central importance -- implies a serious consideration of saltational mechanics.  (Gould 2002: 1142)

"Nevertheless, I note … the relevance of developmental themes to punctuational patterns at these larger, and very different, scales of explanation. For example, several authors have argued that our emerging concepts of deep homology might help to elucidate such marcroevolutionary “classics” of large-scale rapidity as the Cambrian explosion.  Under Lewis’ (1978) original model of evolution from ancestral homonomy (multiple, identical segments by accretion of duplicated Hox genes to achieve differentiation of specialized parts along the body axis, the Baupläne of the major animal phyla must originate separately and gradually [same claim was made about evolution of eyes, hearts, etc.], as each added developmental component permits further differentiation.  How, then, could so many basic designs make such a coordinated first appearance in five to ten million years, unless some genetic glitch or unknown environmental trigger initiated a rampant episode of duplication in many lineages simultaneously, or unless the pattern only represents an artifact of preservation, rather than the actual macroevolutionary event? (Gould 2002: 1142-1143)

"But the first fruits of evo-devo … have reversed this scenario by documenting a full complement of Hox genes in the most homonomously segmented invertebrate bilaterian phyla, thus suggesting the opposite process of loss and divergence for the differentiation of numerous complex and specialized patterns from initial homonomy (De Rosa et al. 1999). The puntuational character of the Cambrian explosion seems far easier to understand if the basic regulatory structure already existed in ancestral homonomous taxa, and the subsequent diversification of Baupläne therefore marks the specialization and regionalization of potentials already present, rather than a dedicated and individualized addition for each major novelty of each new Bauplan.  The Cambrian explosion still requires a trigger (see Knoll and Caroll, 1999, for a discussion of possible environmental mediators, including the classical idea of an achieved threshold in atmospheric oxygen), but our understanding of the geological rapidity of this most puzzling and portentous event in the evolution of animals will certainly be facilitated if the developmental prerequisites already existed in an ancestral taxon. (Gould 2002: 1143)

"Knoll and Carroll (1999, p. 2134) stress this point in a section of their article entitled “Cambrian diversification: So many arthropods, so little time.” The add …:

"The entire onychophoran-anthropod clade possesses essentially the same set of Hox genes that pattern the main body axis. Thus, Cambrian and recent diversity evolved around an ancient and conserved set of Hox genes ….  Most body plan evolution arose in the context of very similar sets of Hox genes, and thus was not driven by Hox gene duplication … Bilaterian body plan diversification has occurred primarily through changes in developmental regulatory networks rather than the genes themselves, which evolved much earlier."

"… [T]he possibility and meaning of evolutionary saltation at the organismic level of discontinuity across generations we may at least assert a case for plausibility, so that, at the very least, this perennially contentious subject will not be dismissed a priori. First of all, we cannot deny either the existence of such large and discontinuous phenotypic shifts in mutant organisms, or the conventional basis assigned to them: small genetic alterations with major developmental consequences. For example, a single base substitution in bicoid, the maternal gene product that sets the AP axis by supplying positional information within the Drosophila larva, can reverse the axes of symmetry (Frohnhofer and Nusslein-Volhard, 1986; Struhl et al., 1989). Of this and other cases, Akam et al., in the introduction to their 1994 book on The Evolution of Developmental Mechanics write (1994, p. ii): “It is commonplace of developmental genetics that minimal genetic change can lead to the most dramatic morphological effect.” (Gould 2002: 1143-1144)

"(....) Of this interesting correlation between constraint and saltation, Fitch concludes (1997, pp. 166-167): “Because single genetic changes can be postulated for some of the evolutionary change in the male tail, I predict that many evolutionary changes in morphology will have resulted mainly from changes in single loci … Because the power of selection is limited by variation, such developmental constraints could cause significant bias [directionality] in the evolution of form.” (Gould 2002: 1147)

[Gould goes on to caution that it is to early to tell what role such "saltationary" mutations may play in evolution, (see p. 1144 for valid reasons to be cautious), saying]

"(....) In any case, and however important such saltational changes may be in establishing fundamental evolutionary novelties (my own betting money goes on a minor and infrequent role), phyletic discontinuity at lower taxonomic levels, based on small genetic changes with large regulatory effects, has been documented in several cases." (Gould 2002: 1146)

Many other scientists are making far stonger assertions that saltation is not only plausible, but is likely! I could amass a larger number of citations on just this issue from recent statements. One needs to only read Jeffrey H. Schwartz (1999) "Sudden Origins: Fossils, Genes, and the Emergence of Species" to see that that this cant that saltation is impossible is being recosidered from many different angels:

"[T]he preoccupation with the notion that there was a trend toward becoming increasingly humanlike has been wedded to speculations about the processes of natural selection and the sequence of adaptations that could have brought about this putative transformation from ape to human. While other disciplines in evolutionary science have expanded their appreciation of different possible mechanisms and processes of evolutionary change, the study of human evolution has been firmly planted in the traditional dogmas of Darwinism, incluing the belief that evolutionary change manifests itself only through an insensible series of infinitesimally small modifications.  Clearly, the search for ancestors and intermediates that has dominated -- and continues to dominate -- the field of paleoanthropology attests to such beliefs.  But what if this isn't the way it happened?" (p. 33)

Or consider Jeffrey S. Levinton's "Genetics, Paleontology, and Macroevolution" and the section on "Constraint and Saltation" that states:

"Time and again, the concepts of constraint and saltation have been formulated in terms of development. Developmental constraints are nonrandom channelizations of evolutionary direction due to limitations imposed by complex interactions of gene expression and epigentic interactions, such as tissue inductions, in the developing organism.  The disruption of such interactions may strongly influence fitness and therefore restrict evolutionary change.  In the context of development, saltations are rapid evolutionary fixations of phenotypic discontinuities guided by developmental controls, which do not permit continuity of form in polymorphic populations."

"(….) A developmental notion of macromutation springs from the nature of development described above. If a simple transplant places toes on wings or replaces scales with feathers, why couldn’t evolution occur in major steps?  Some have seen such discontinuities in development as a vehicle for major evolutionary jumps (Goldschmidt 1940; Gould 1980a; Lovtrup 1974; Maderson et al. 1982; Schinderwolf 1936, 1950), or at least see them as possible stuff of major saltations (Alberch, Gould, Oster, and Wake 1979; Frazzetta 1970)" (p. 157-162)

This page really needs to be reevaluated in light of current scientific knowledge.

Dogyo (talk) 21:19, 8 February 2009 (UTC) Dogyo


 * You say "Gould pointed out that ... it became almost a dogma that evolution proceeded along gradualist lines with no real so-called “saltations.”" He also spent much of his professional life explaining that his punctuated equilibrium theory is not saltationist.  His description of gradual change ( immediately proceeding the snippet I just quoted in your text ) is a straw man.  No biologist believes that evolution takes place at the specific gradual and steady pace Gould attacks.

Stephen Jay Gould appears to be your only source of information. I submit that you've chosen a highly opinionated, not especially neutral source. Steve Gould made a crusade out of trying to undermine theories to which he attributed right-wing implications. He insisted that biology has no role in human nature apart from hunger for food and need for sleep. The man fell victim to a the fallacy of wanting something to be true, and thinking it is. His pervasive anti-Darwinian stance is an extension of this, and many of his hypotheses on evolution are taken with extreme skepticism. The zoologist Richard Dawkins devotes a chapter to some of the details in his book The Blind Watchmarker, Steven Pinker takes Gould to task in The Language Instinct as well as The Blank Slate, and the list of authors with factual, experiment-based objections to Gould's non-taxonomy work can fill a book of its own. —Preceding unsigned comment added by 207.138.32.33 (talk) 19:26, 10 February 2009 (UTC)

The reason I cited only Gould was 1) time constraints, 2) he does a good job of summarizing the issue historically, and 3) his SET was the only reference in this article. He correctly points out that the issue is being debated once again (and continues to be a discussed and debated in current literature) due to recent empirical findings within the field of Evolutionary Developmental Biology. Within this ongoing debate or discussion in the literature there is a diversity of views of the underlying genetic mechanism(s) of "saltatory hereditary mechanisms" (Laubichler et al. 2007), ranging from Jeffrey H. Schwartz "Sudden Origins" to Robert G. B. Reid's "Biological Emergences: Evolution by Natural Experiment," or Hall et al. "Environment, Development, and Evolution: Toward a Synthesis" in which they address the evidence of epigenetics (See Muller and Newman 2003) and phenotypic plasticity under the heading "Gradual or Saltatory Ontogeny." Sapp (2003) notes these "non-Mendelian mechanisms for evolutionary change were left unconsidered by the classical Darwinian evolutionists (p. 216)," and addresses the question of saltation within the context of symbiosis (p. 236; 247; 249; 250-251). Or West-Eberhard's (2003) "Developmental Plasticity and Evolution" which covers some interesting history of this idea and dicusses the fact that the "'genetic gradualism' does not eliminate the possibility that novelty originates via a saltatory or large mutationally or enviromemtally induced phenotypic change, subsequently gradually accommodated (p. 479)." Or see discussions of "homeotic mutations" in Wilkins (2002), or Prothero (2007: 98) on the same findings emerging from Evolutionary Developmental Biology. Or, consider the information emerging from comparative genomics, discussed by Gregory (2005) in "The Evolution of the Genome" in the chapter entitled "Macroevolution and the Genome."

It is also incorrect to claim that "No biologist believes that evolution takes place at the specific gradual and steady pace Gould attacks." (Mr. Anonymous above) The history of biology is replete with biologists making this very claim, right up to the recent times. I could amass pages of quotations of just such claims. The argument generally ran that evolution proceeded by "infinitesimally small" genetic changes that accumulated over time, and that any genetic mutations that caused major morphological change would lead to "monstrosities" that would not survive or be uanable to find a mate. Both of these asumptions are now being seriously questioned in todays science of Evo Devo. The only straw man here is Mr. Anonymous attempt to ignore the relevance of Gould's argument in SET.

Sadly, this is typical Wikipedia and one grows very tired of arguing with such sillness.

The issue of "saltation" regardless of what term is used (homeotic mutations, homeotic genes, macromutation, saltatory hereditary mechahinsms, etc.) is certainly being discussed within the scientific literature, and it is not so black-and-white as some would like to paint it. When a close look is taken at the actual scientific literature, it becomes clear the question of "saltatory hereditary mechanisms" is far from resolved, regardless of where any individual scientists falls in the continuum of proposed underlying genetic mechanisms, and while Gould took the conservative position, he was correct when he said:

"[T]he possibility and meaning of evolutionary saltation at the organismic level of discontinuity across generations we may at least assert a case for plausibility, so that, at the very least, this perennially contentious subject will not be dismissed a priori. First of all, we cannot deny either the existence of such large and discontinuous phenotypic shifts in mutant organisms, or the conventional basis assigned to them: small genetic alterations with major developmental consequences. For example, a single base substitution in bicoid, the maternal gene product that sets the AP axis by supplying positional information within the Drosophila larva, can reverse the axes of symmetry (Frohnhofer and Nusslein-Volhard, 1986; Struhl et al., 1989). Of this and other cases, Akam et al., in the introduction to their 1994 book on The Evolution of Developmental Mechanics write (1994, p. ii): “It is commonplace of developmental genetics that minimal genetic change can lead to the most dramatic morphological effect.” (Gould 2002: 1143-1144)

I find it a bit ironically humorous that the above fuller quotations taken in context from Gould’s Structure of Evolutionary Theory (SET) that reveal his more nuanced views on the subject of salutatory hereditary mechanisms is summarily dismissed with the statement “Stephen Jay Gould appears to be your only source of information,” when I chose Gould because the only reference used in this article was Gould’s SET. And Dawkins is not "highly opinionated, [and] not especially neutral source"?

Yes, it is true that his theory of punctuated equilibrium has been mistakenly associated with “saltation” by some, but that is a separate and different issue than his fuller and more nuanced views on the subject of saltation expressed in SET. Yet, from the rather out-of-context usage of the quotation one would hardly get a very well rounded picture of Gould's thoughts on this subject of saltation expressed in SET. Is it not the goal of Wikipedia to present a balanced and accurate picture of the facts? Then certianly Gould's fuller in context comments regarding the plausibility of saltation and the caution it cannot "be dismissed a priori," a fact increasingly being born out in the current scientific literature, are relevant to this article.

Sapp correctly notes in his Epilogue that "Most of the great controversies and conceptual oppositions of the nineteenth century are still present at the beginning of the twenty-first century," including the "gradualism versus saltationism" debate. (Sapp 2003: 267) And history is bearing Gould's observation out in spades. The citations could go on and on, but what is the point, when my only point is that this is an issue that is currently being discussed, and that there exists a diversity of views, ranging from the ulta-Darwinian Panselectionist (See Gregory) to the re-emergence of discussions around issues of saltatory hereditary mechanisms explained by epigenetics and associated regulatory and developmental genetic pathways. Woese (2005) is far from the only prominent scientist raising this issue once again.

Reference List

1. Balon, Eugene K. Epigenetic processes, when natura non facit saltum becomes a myth, and alternative ontogenies a mechanism of evolution. Environmental Biology of Fishes. 2002; 651-35.

2. Hallgrimsson, Benedikt and Hall Brian. Variation: A Central Concept in Biology. Amsterdam: Elsevier Academic Press; 2005; p. 511.

Waddington and Schmalhausen, two of the few biologists actually interested in connecting development and evolution during the height of influence of the modern synthesis, introduced the first phenomenon, what Waddington (1942) termed “canalization.” (….)  The evolution of discrete traits has been a problem in evolutionary theory since its inception, especially because these traits often have a complex genetic architecture so that single mutations are unlikely to produce the necessary change (but see the next section for a situation in which this could occur). Goldschmidt’s notion of “hopeful monsters” has been universally panned, but several lines of recent evidence suggest that saltational change may have played a role in evolution (Dietrich, 2003). Probably most important for reviving at least some acceptability for the notion of sudden change was the discovery of the genetic basis of change in the numbers or arrangements of segmental or meristic traits. The classic instance was the finding that Hox gene mutation could produce extra wings or leg-antennal substitutions I flies, examples of traits considered long ago in this context by William Bateson (Bateson, 1894). Change in segment number can be brought about by mutation in a single gene. Though the change is often not completely viable or competitively “fit,” it shows that small genetic change can lead to organized morphological change, and some of this resembles evolutionary changes in body plan (Carroll et al., 2001)

[See pp. 10, 13, 15, 18-22, 127]

3. Dietrich, Michael R. From Hopeful Monsters to Homeotic Effects: Richard Goldschmidt's Integration of Development, Evolution, and Genetics. American Zoologist. 2000 Nov; 40(5):738-747.

4. Levinton, Jeffrey S. Genetics, Paleontology, and Macroevolution. Cambridge: Cambridge University Press; 2001; pp. 157-162.

(....) We are now at the threshold of a completely new period, in which development and genetics are being connected in great detail. At first, this became apparent from the emerging understanding of a widespread homeobox sequence that united all of the triploblastic animals at least. Now, modern methods of gene sequencing, manipulation of gene expression, and tracing of spatial patterns of gene expression have resulted in an explosion of information that is not leading, as yet, to many useful evolutionary rules. So far, we are seeing the same errors promulgated in lionizing past laws of ontongeny and phylogeny. Beliefs in major genetic revolutions, master switch genes, and other universals are beginning to form a modern version of the ontogentic laws of old, with little consideration for the possibilities of convergence in developmental gene function. Nevertheless, the new tools allow us to better peak through the curtains, and the early flush of enthusiasm will likely be followed by substantial advances in development evolution.

Phylogeneticists and Developmentalists

(….) The developmentalists claim that “the diversity of structures that have been formed through the process of evolution is constrained by the rules which govern pattern formation during development” (Stock and Bryant 1981, p. 432). As such, evolutionary change of necessity is the evolution of developmental sequences. The individual, therefore, is treated in terms of its entire ontogeny, and development is therefore both the constraint and target of selection. There is a developmental toolbox, and certain tools may be used in many contexts, but this does impose a possibly limited set of alternative developmental pathways.

(….) [M]orphological structures often come as complete structures or not at all. Of equal interest is the importance of localization in development. Embryos develop only as the result of a complex series of timing events that bring different cells into contact or place cells or molecules of restricted developmental potency in a proper environment for induction. The spatial position of cell groups seems crucial in the generation of morphological patterns, owing to

•	Localized intercellular movement and regional movement of dissolved substances that often set gene expression in motion (Garcia-Bellido, Rippoil, and Morata 1973; Summerbell 1981; Turing 1952; Wolpert 1969) •	Transcellular electric fields (Jaffe and Stern 1979; Nuccitelli 1983) •	Mechanochemical interactions (e.g., Odell, Oster, Alberch, and Burnside 1981; Oster, Murray, and Harris 1983) •	Specialized cell adhesion molecules (Edelman 1986)

Must these not influence the direction of evolution? These two phenomena integrity of structure and topological restriction of development  suggest that an embryo can be transformed in only limited number of directions during the process of development and evolution. That is the fundamental message about form that Richard Goldschmidt’s pioneering book Physiological Genetics (1938), derived from Spémann (1938), underscored so well.

Some examples of developmental mutants show the discontinuous and often spectacular nature of possible structural change. Consider the cyclops mutant (Bowen, Hanson, Dowling, and Poon 1966) of brine shrimp males. After the fourth instar, the lateral eyes move forward and fuse together, forming a single large compound eye by the ninth instar. During this fusion, the ganglia and nerves of the two optic stalks fuse; the resultant eye resembles the normal medial eye of the cladoceran Leptodora. Thus, a quirk of development has caused a structure to change from that characteristic of one taxonomic order to another! The development of the vertebrate limb shows similar quantum steps.

(….) A developmental notion of macromutation springs from the nature of development described above. If a simple transplant places toes on wings or replaces scales with feathers, why couldn’t evolution occur in major steps? Some have seen such discontinuities in development as a vehicle for major evolutionary jumps (Goldschmidt 1940; Gould 1980a; Lovtrup 1974; Maderson et al. 1982; Schinderwolf 1936, 1950), or at least see them as possible stuff of major saltations (Alberch, Gould, Oster, and Wake 1979; Frazzetta 1970)

5. Matthew I. Goldsmith, Shannon Fisher Rick Waterman and Stephen L. Johnson. Saltatory control of isometric growth in the zebrafish caudal fin is disrupted in long fin and rapunzel mutants. Developmental Biology. 2003 Jul 5; 259(2):303(15).

6. Schwartz, Jeffrey H. Sudden Origins: Fossils, Genes, and the Emergence of Species. New York: John Wiley & Sons; 1999.

7. Laubichler, Manfred D. and Maienschein Jane, Editors. From Embryology to Evo-Devo: A History of Developmental Evolution. Cambridge: MIT Press; 2007; p. 173.

8. Minelli, Alessandro and Fusco Giuseppe, Editors. Evolving Pathways [Key Themes in Evolutionary Developmental Biology]. Cambridge: Cambridge University Press; 2008; pp. 50-51.

9. Reid, Robert G. B. Biological Emergences: Evolution by Natural Experiment. Cambridge: MIT Press; 2007; pp. 50, 184, 245, 271, 276, 330, 48. (The Vienna Series in Theoretical Biology.)

10. Hall, Brian K. Pearson Roy D. and Müller Gerd B. Environment, Development, and Evolution: Toward a Synthesis. Cambridge: The MIT Press; 2003. (The Vienna Series in Theoretical Biology.)

11. West-Eberhard, Mary Jane. Developmental Plasticity and Evolution. Oxford: Oxford University Press; 2003; p. 3.

12. Muller, Gerd B. and Newman Stuart A. wip, ed. Origination of Organismal Form: Beyond the Gene in Developmental and Evolutionary Biology. Cambridge: MIT Press; 2003. (The Vienna Series in Theoretical Biology.)

13. Wilkins, Adam S. The Evolution of Developmental Pathways. Massachusetts: Sinaur Associates; 2002; pp. 369-371; 389.

Chapter 12 Speciation and Developmental Evolution

The Genetic Basis of Species versus Larger Taxonomic Differences

It is the first issue -- the nature of the genetic differences that lead to speciation -- that has received the most attention and that has been the subject of the most controversy. The focus here is not on the genetic differences that lead to reproductive isolation, which may involve artifactual epistatic interactions, but on those genetic differences that lead to differential adaptation on the road to the formation of different species.

The starting point of most discussions is Fisher's argument that adaptive evolution is driven by mutations of individually minute effect (Fisher, 1930) -- "micromutations," to use the term from the older literature. To the extent that species formation is accompanied by or driven by such adaptive evolution, developmental evolution in species formation would also consist of changes of individually tiny effect. This view, however, has always seemed deeply implausible to numerous developmental biologists (e.g., Goldschmidt, 1940; Gilbert et al., 1996) and patently untrue to the majority of paleontologists, based on their study of the fossil record (Valentine and Erwin, 1987; Gould, 1994; Erwin, 1999). To many members of these groups, an important role for mutations of large, or at least visible, phenotypic effect -- so-called "macromutations" -- has seemed far more probable than not.

Nevertheless, the gulf between evolutionary geneticists on the one hand and developmental biologists and paleontologists on the other has narrowed in recent years, with a shift toward the position of the latter group. The new consensus is that some mutations of large phenotypic effect can and do play a part in speciation. (p. 462)

[Note: Gould after reviewing the new evidence of evo-devo, modified his previous views somewhat, making room for the "plausibility" of such macromutations (saltations), which were not part of his theory of punctuated equilibria, and which relied solely on allopatric speciation as the mechanism of his punctuations occuring over periods of 10 to 40 thousand years, which he termed a "geological moment." The truth -- fact -- is that a bedding plane which represents a "geological moment" is only resolvable to 10,000 to 40,000 years, and Gould used statistical methods to determine changes in morphology over time which he associated with punctuational events. He admits in his book The Structure of Evolutionary Theory that one could not differentiate between a sudden saltation and accelerated allopatric speciation, since both events would leave the same data signature in the bedding plane. In other words, it is an assumption that the process of speciation in punctuated equilibria is due to allopatric speciation, although at an accelerated rate, after a period of stasis. It is also a fact that the fossil record does not contain the level of detailed data required to distinquish between these two events; hence, at the time Gould developed his theory one was left in the position of having to choose between one of two assumptions; allopatric speciation at an accelerated rate, or sudden saltation. The recorded data in the fossil record would be exactly the same, and one could not distinguish empirically between the two. The new evidence of molecular biology, developmental genetics, and evolutionary developmental biology (evo-devo) are adding to the plausibility of sudden saltations, a point which Gould himself (2002: 1143-1144) argues based upon this new evidence, can no longer be dismissed a priori.]

14. Prothero, Donald R. Evolution: What the Fossils Say and Why it Matters. New York: Columbia University Press; 2007; p. 99.

15. Gregory, T. Ryan, ed. Macroevolution and the Genome. In The Evolution of the Genome. Amsterdam: Elsevier Academic Press; 2005.

16. Cabej, Nelson R. Neural Control of Development: The Epigenetic Theory of Heredity. New Jersey: Albanet; 2004.

17. Cabej, Nelson R. Epigenetic Principles of Evolution. New Jersey: Albanet; 2008.

18. Sapp, Jan. Genesis [The Evolution of Biology]. Oxford: Oxford University Press; 2003.

As the relations between development and evolution were explored in the last decades of the twentieth century, mutations in those genes that regulate development also assumed great significance. Regulatory (homeobox) genes were reported that affected whole sets of genes, and some paleontologists [and developmental geneticists, etc.] have emphasized that mutations in such regulatory genes result in large discontinuous evolutionary changes (a reshuffling of parts) and may be a macromechanism of evolution. But symbiosis--the inheritance of acquired genomes, wholes or parts--was trivialized or ignored by paleontologists. Gould himself regarded teh symbiotic origin of mitochondria and chloroplasts as "entering the quirky and incidental side" of evolution (pp. 250-251).

19. Woese, Carl R. Evolving Biological Organization. In Microbial Phylogeny and Evolution: Concepts and Controversies (Jan Sapp, ed.). Oxford: Oxford University Press; 2005; pp. 107-109. The most important, if not the only, thing that can be said right now about the progression from pre-Darwinian progenote to cells typical of the Darwin era (i.e., modern cells), is that in the process the cell design becomes more integrated. Connectivity, coupling (among componentry) is key to the nature of that transition. The cell is a complex dynamic system. Complex dynamic systems characteristically undergo saltations at “critical points.” Drastic changes in the system result. An increase in the connectivity of a system is one factor that can bring it to such a critical point. Does the Darwinian Threshold, then, denote a critical point in the evolutionary process? I say it does. We can be confident in any case that in the full evolutionary course, from an abiotic earth to modern cells and organisms, evolutionary saltations must have occurred. The transition from the nondescript, horizontally [non-Darwinian] intermeshed, and simple progenote to the complex individual cell lineages (with stable genealogical traces and vertical descent) that we now surely has the feel of a saltation. (p. 109)

20. Kingsley, David M. et. al. Adaptive Evolution of Pelvic Reduction in Sticklebacks by Recurrent Deletion of a Ptix1 Enhancer. Sciencexpress, 10 December 2009.

The molecular mechanisms underlying major phenotypic changes that have evolved repeatedly in nature are generally unknown.... These studies illustrate how major expression and morphological changes can arise by single mutational leaps in natural populations, producing new adaptive alleles via recurrent regulatory alterations in a key developmental controle gene. (Kingsley 2009: 1)

Evolutionary biology has been animated by long-standing debates about the number and type of genetic alterations that underlie evolutionary change. Questions about the role of genetic changes of infinitesimally samll versus large effects; the origin of traits by either natural selection or genetic drift; and the relative importance of coding and regulatory changes in evolution are currently being actively investigated. (Kingsley 2009: 1)

Dogyo (talk) 15:31, 26 February 2009 (UTC) Dogyo

In "Darwins Dangerous Idea" Daniel Dennett deals at length with a number of Stephen Jay Gould theories, and is, in my view succesful in either refuting them, or demonstrating that they lie within Neo-Darwinism. For example he dissects Goulds Punctuated Equilibrium, and is able to show that once Gould had corrected and re-explained his position, PE, was in fact nothing more than a close up analysis of gradualism. I am afradi that Stephen Jay Gould, seems to have brought an agenda to the table, and its smacks of creationism. —Preceding unsigned comment added by Miltonred (talk • contribs) 00:01, 31 March 2009 (UTC)

Daniel Dennett has an agenda. It is called Panselectionism and it is seen in the comment above in which any deviation from Panselectionist dogma is labeled "creationism." Of course, this is a red herring and straw man argument, for that would mean that the ever increasing number of citations appearing in the literature, only a few of which are listed above, are all trying to sneak creationism onto the table. What utter nonsense to attempt to label this legitimate discussion within the field of theoretical evolutionary biology as an attempt to sneak creationism onto the table. There is a growing body of empirical evidence from evo-devo that indeed “saltations” are possible and “saltatory hereditary mechanisms” exist. It has absolutely nothing to do with creationism and everything to do with the flood of evidenced emerging from the new fields of Evolutionary Developmental Biology and Comparative Genomics and our unfolding empirical understanding of epigenetics and the regulatory genome.

Gould after reviewing the new evidence of evo-devo, modified his previous views somewhat, making room for the "plausibility" of such macromutations (saltations), which were not part of his theory of punctuated equilibria, and which relied solely on allopatric speciation as the mechanism of his punctuations occuring over periods of 10 to 40 thousand years, which he termed a "geological moment." The truth -- fact -- is that a bedding plane which represents a "geological moment" is only resolvable to 10,000 to 40,000 years, and Gould used statistical methods to determine changes in morphology over time which he associated with punctuational events. He admits in his book The Structure of Evolutionary Theory that one could not differentiate between a sudden saltation and accelerated allopatric speciation, since both events would leave the same data signature in the bedding plane. In other words, it is an assumption that the process of speciation in punctuated equilibria is due to allopatric speciation, although at an accelerated rate, after a period of stasis. It is also a fact that the fossil record does not contain the level of detailed data required to distinquish between these two events; hence, at the time Gould developed his theory one was left in the position of having to choose between one of two assumptions; allopatric speciation at an accelerated rate, or sudden saltation. The recorded data in the fossil record would be exactly the same, and one could not distinguish empirically between the two. The new evidence of molecular biology, developmental genetics, and evolutionary developmental biology (evo-devo) are adding to the plausibility of sudden saltations, a point which Gould himself notes (2002: 1143-1144), and was the basis of his claim that saltation can no longer be dismissed a priori.

Dogyo (talk) 16:25, 11 April 2009 (UTC) Dogyo

Darwinism is flawed according to the macromutation theory
Goldschmidt and Lovtrup who have both supported the macromutation theory as opposed to Darwin:

"It is good to keep in mind ... that nobody has ever succeeded in producing even one new species by the accumulation of micromutations. Darwin's theory of natural selection has never had any proof, yet it has been universally accepted." (Prof. R Goldschmidt PhD)

Micromutations do occur, but the theory that these alone can account for evolutionary change is either falsified, or else it is an unfalsifiable, hence metaphysical theory. I suppose that nobody will deny that it is a great misfortune if an entire branch of science becomes addicted to a false theory. But this is what has happened in biology: ... I believe that one day the Darwinian myth will be ranked the greatest deceit in the history of science. When this happens many people will pose the question: How did this ever happen?" (S Lovtrup PhD, Darwinism: The Refutation of a Myth (London:Croom Helm, p.422))

As these scientists have claimed, so why is there hardly anything about their theories on the article? Liveintheforests (talk) 16:44, 15 June 2011 (UTC)


 * And both are mentioned (Goldschmidt prominently so) in Macromutation -- the article that directly discusses "macromutation theory". It is unclear to what extent this article covers material beyond that article's scope, but either way I don't see why additional material on them here is appropriate -- either this article should be redirected to that one, or it is material beyond macromutation that is needed here. HrafnTalkStalk(P) 17:43, 15 June 2011 (UTC)


 * From what i have read Saltation is macromutation. It was first put forward by a group of scientists in the early 1900s to clarify that, it can be found in some of Bowlers books. Later Goldschmidt and Lovtrup took the theory further. Goldschmidt and Lovtrup are deemed as heretics but the mainstream scientific community, that is something i have never understood, becuase they were still evolutionists they were trying to improve the evolutionary theory not deny it. What needs to be done, is the saltation information needs to be moved to the macromutation page. Liveintheforests (talk) 18:49, 15 June 2011 (UTC)


 * The criteria for scientific acceptance of new hypotheses is not 'heresy' versus orthodoxy -- it is whether the hypothesis adequately explains existing facts and anticipates (i.e. predicts) new facts. Given that none of these facts would appear to support the claim that a macromutation has occurred, or even is feasible, it would appear that this hypothesis has failed this test. Scientific research of course involves the investigation of many blind allies -- but their investigation is seldom notable -- nor is being stubbornly wedded to them necessarily commendable. HrafnTalkStalk(P) 19:18, 15 June 2011 (UTC)

Creationism section
Notice that there are no references for the claims made in the creationism section, and the only two footnotes somewhat misleadingly imply that they are providing sources for the claims about creationism, when they are merely referencing Gould's own work, etc. It seems the section should be sourced with one or two specific examples, or removed. Thoughts? --Bob Enyart, Denver radio host at KGOV (talk) 16:57, 28 March 2012 (UTC)


 * What exactly are you challenging? Are you claiming that creationist do not confuse saltation with punctuated equilibrium? Or that they do not see fossil record gaps as "proof" that evolution is flawed? These are standard creationist arguments that no matter how many proofs are shoved their way (e.g. the fact that even with the expected gaps, the sequence of evolution is consistent, i.e. there are no precambrian rabbits or real-life Flintstones) they do not change it, it's almost a case of WP:BLUE. Do have a look at Sunderland's Darwin's Enigma, Menton's The Hopeful Monsters of Evolution, Answers in Genesis, Morris' Scientific Creationism, and the Watchtower's Life--How Did It Get Here?. It's presumably correctly sourced in Gould's work in its original publication (being an actual scientific article in an academic journal), so unless you have sources from reliable sources saying otherwise, no, removal is out of the question. -- O BSIDIAN  †  S OUL  18:04, 28 March 2012 (UTC)

The link to Gould's 1972 peer-reviewed article does not establish the "common practice" claim in the first sentence. It doesn't even speak of Hopeful Monster, etc., and doesn't mention Gish, Morris, creationists, etc. His reference to the JWs has nothing to do with confusing Hopeful Monster and Punctuated Equilibrium. Perhaps if we use the reference that follows, it's currently numbered 15, to his article in Natural History (not peer-reviewed I believe). At least that NH piece provides a quote attributed to a creationist (unsourced if I recall) that does make the claim. So replacing the [14] reference with the [15] reference will help. However, to say that this is "common practice" for creationists really should be sourced. If any WP-worthy reference within the last 25 years shows two or more known creationists or creation ministries conflating these two ideas, then I'd think that claim as written should stand and be so referenced. But a brief quote from about half-a-century ago doesn't seem to justify "common practice." Thoughts? Bob Enyart, Denver radio host at KGOV (talk) 17:32, 11 May 2012 (UTC)

It's been about six months and I haven't come across WP-worthy references within the last 25 years showing two or more popular creationists conflating HM with PE, so as per the discussion above, I'd like to remove the "common practice" and change it to "Some creationists have..." Bob Enyart, Denver radio host at KGOV (talk) 03:59, 9 November 2012 (UTC)

Maybe this section should be deleted.  What is the "Use by creationists" the section title hints at ??? The above discussed conflation of this with PE but the article section is not clear about what (if any) "Use" was done with that combination. I'm seeing this is not among the common Objections to Evolution, and thinking that if it was hard to find little or none -- then it has shown WP:WEIGHT is below the level of having such a section. That one or two folks go 'and Darwin was wrong here too' seems just normal random advocacy; need to show actually that it's common or that it's got big impact to Saltation to stay. So will wait a while and unless someone has significance will pull it.... Markbassett (talk) 17:39, 21 May 2015 (UTC)

Balanced gene drive
A saltational mechanism known as "balanced gene drive" was proposed by Michael Freeling. He mentions this in one of his papers here and in this paper. If there is an expert on the subject perhaps you can help adding this into the article. 82.1.154.153 (talk)

Compressed DNA
The recent discovery that DNA is compressed (like a zipped computer file) and requires a control section to reassemble proteins in the proper order, implies that a small mutation in the control section could lead to saltation. — Preceding unsigned comment added by 198.203.213.6 (talk) 16:08, 11 August 2015 (UTC)

We have met the Hopeful Monster, and he is us!
Somebody finally tracked down a really impressive recent change in the genome: ARHGAP11B. See. Though I'm sure there's been fine-tuning of expression afterward, it is entirely possible that much of such a change could have been created in a single gene duplication event, causing a notable increase in human intelligence (waiting on word about the mice...)

For Wikipedia I can't make this connection on my own, but it's worth keeping an eye out for someone making this connection in print. Wnt (talk) 02:12, 28 February 2015 (UTC)

Endosymbiotic theory as an example of saltation? Horizontal gene transfer? More details would be relevant
It's mentioned briefly, but no explanation is given. To me it seems only compatible with saltation under that notion of the proto-host-organism "trying to eat" a bacteria, engulfing it, but somehow failing to digest it, and that being good for both immediately. But AFAIK at least more contemporary versions would have it as a more gradual ecological relationship possibly starting as very-mild-parasitism, changing to commensalism, and then mutualism. Or maybe starting already more mutual or commensal, but without so much of the "accidentally trying to eat, failing, and that being a big luck for both" simplistic notion. Original mild/asymptomatic infection evolving gradually as occur in many cases of endosymbiosis vs sudden/episodic predation and failed digestion. Although there's one case that may kind of match somewhat the description, the infection of some insects with Wolbachia being somewhat mutualistic but also an instant "speciation," although with no observable phenotypical "saltation" other than not being able to produce offspring with non-infected potential mates of the "former" species. Something along those lines.

Horizontal gene transfer is also somewhat weird without any example, since it doesn't necessarily produce any significantly large phenotypical effect, although it may sometimes, I'm not sure it's noteworthily more likely to do so than plain "endogenous" mutations. 45.234.133.177 (talk) 04:31, 14 October 2023 (UTC)