What on earth is “mutationism”? Some possible answers

The term “mutationism” appeared in the early 20th century in regard to the views of early geneticists such as de Vries, Bateson, Punnett, and Morgan (e.g., Poulton, 1909 or McCabe 1912). These leading thinkers did not use “mutationism” to describe their own diverse views.[1] Perhaps they thought of themselves as free thinkers, not tied to any ideology or “-ism”.

In the contemporary literature, “mutationism” is most often a strawman in which evolution takes place by dramatic mutations alone, without selection (see the conceptual immune system of neo-Darwinism). This pejorative use of “mutationism” continues today in the writings of Synthesis gatekeepers such as Futuyma (2023) or Svensson (2023).

Yet the 2013 book “Mutation-driven Evolution”, by Masatoshi Nei— a pioneer of molecular evolutionary genetics who passed away in early 2023—, brought renewed attention to the idea of a broad alternative to traditional thinking focused on mutation rather than selection. Among published reviews of the book, only Wright rejects Nei’s thinking as mistaken, referring to it as “Mutationism 2.0.” Five other reviews try to explain Nei’s position sympathetically, without necessarily endorsing it. Three reviews do not mention “mutationism” (Brookfield, Galtier, Weiss). The review by Gunter Wagner entitled “The changing face of evolutionary biology”, like my review for Evo & Devo, attempts to identify a sympathetic meaning of “mutationism” appropriate for Nei’s distinctive project, focusing on the importance of mutations in evolution.

One might be tempted to avoid the term “mutationism” (along with “saltationism” and “orthogenesis”) on the grounds of being toxic. To use this term is to risk ridicule and invite misunderstanding. Why do that, when one’s goal is to communicate with readers? I avoided these terms myself for many years, on precisely these grounds. However, eventually I decided not to acquiesce to rhetorical tactics designed to browbeat dissenters using strawman arguments. As we say here in the US, that would be letting the terrorists win. Promoting good intellectual hygiene in our field means calling out fallacies, and addressing alternative views fairly and rigorously, without rhetorical trickery. [2]

If “selectionism” is allowable to designate a focus on selection, without denying a role for mutations in evolution, then “mutationism” is allowable to designate a focus on mutation that does not deny selection.

If there are distinctive features of the views of Nei and the early geneticists, nothing prevents us from using “mutationism” to denote those features. If “selectionism” is allowable to designate a focus on selection, without denying a role for mutations in evolution, then “mutationism” is allowable to designate a focus on mutation that does not deny selection. In my own thinking, I tend to associate “mutationism” with a non-exclusive explanatory position, with the lucky-mutant conception of evolutionary dynamics (see the shift to mutationism is documented in our language), or with a school of thought.

TLDR

Possible meaning of mutationismType of meaning
evolution happens by dramatic mutations alone, without selectionStrawman from Synthesis tribal mythology, employed by gatekeepers to police orthodoxy
identifying distinctive mutational-developmental changes is a uniquely powerful way to explain the evolution of formExplanatory position on what kinds of causal attributions are meaningful, key to evo-devo
reconstructing mutational changes provides uniquely reliable knowledge of past evolutionMethodological position on which causes are most accessible to scientific methods, also key in evo-devo
the timing and character of events of mutation determine the timing and character of evolutionary changeEmpirical position on evolutionary dynamics, e.g., in applications of origin-fixation models
diverse evolutionary phenomena arise from combining mutation and geneticsLoosely defined school of thought associated with Bateson, Punnett and Morgan
a preliminary and imperfect expression of (for instance) a future paradigm of dual causationTransition state mainly of historical interest

The Mutationism Story in Synthesis tribal mythology

In the mainstream literature of evolutionary biology, history is told in a way that makes things turn out right for the Modern Synthesis, e.g., there is literally an “eclipse of Darwinism”— a period of darkness and strife— that ends when the Modern Synthesis solves the problem of evolution. This self-serving view of history is called “Synthesis Historiography” or SH by professional historians (Amundson, 2005). In SH, critics of neo-Darwinism behave irrationally and hold views with obvious flaws, while Darwin’s followers use reason and evidence to establish important truths.

The stories in SH function as a tribal mythology, i.e., scientists who identify culturally with the “Synthesis” tell these stories to each other to affirm their identity, which is based on a shared belief in their fundamental rightness about evolution, and the wrongness of historic opponents. For instance, in the Mutationism Story, the early geneticists are too stupid to understand populations, gradual change, or selection, which they reject, believing instead that evolution happens by dramatic mutations alone, without selection. The problem is solved when Fisher sees what the mutationists are too foolish to see: there is no conflict between gradualism, selection, and genetics. Versions of this fable are given in this blog (e.g., Dawkins 1987, p. 305 of The Blind Watchmaker; Cronin 1991, p. 47 of The Ant and the Peacock; Ayala and Fitch 1997; Futuyma, 2017; Segerstråle 2002, Oxford Encyclopedia of Evolution 2, pp. 807 to 810; Charlesworth and Charlesworth 2009). Here is Dawkins’s version:

“It is hard for us to comprehend but, in the early years of this century when the phenomenon of mutation was first named, it was regarded not as a necessary part of Darwinian theory but as an alternative theory of evolution! There was a school of geneticists called the mutationists, which included such famous names as Hugo de Vries and William Bateson among the early rediscoverers of Mendel’s principles of heredity, Wilhelm Johannsen the inventor of the word gene, and Thomas Hunt Morgan the father of the chromosome theory of heredity. . . Mendelian genetics was thought of, not as the central plank of Darwinism that it is today, but as antithetical to Darwinism. . . It is extremely hard for the modern mind to respond to this idea with anything but mirth”

Dawkins, 1987, p. 305

Actual history contradicts the Mutationism Story. In reality, immediately upon the discovery of genetics in 1900, early geneticists began to assemble the pieces of a Mendelian view of evolution by mutation, inheritance, and differential survival (Stoltzfus and Cable 2014). The multiple-factor theory was immediately suggested by Bateson and others. Here Bateson and Saunders (1902) give a precise verbal rendition of the Hardy-Weinberg paradigm, the first rigorous paradigm of population thinking:

“It will be of great interest to study the statistics of such a population in nature. If the degree of dominance can be experimentally determined, or the heterozygote recognised, and we can suppose that all forms mate together with equal freedom and fertility, and that there is no natural selection in respect of the allelomorphs, it should be possible to predict the proportions of the several components of the population with some accuracy. Conversely, departures from the calculated result would then throw no little light on the influence of disturbing factors, selection, and the like.”

Bateson and Saunders, 1902, p. 130 

Thomas Hunt Morgan won a Nobel prize in genetics. His tendency to refer to “survival” of “definite variations” and to avoid “natural selection” reflects, not a rejection of what we call “selection” today, nor some kind of mental block, but a belief that shifting the goal-posts to avoid accountability is bad for science. For Morgan, the term “natural selection” must be reserved for Darwin’s non-Mendelian theory based on the blending of environmentally stimulated fluctuations (“indefinite variability”), a theory correctly rejected by the scientific community when it was experimentally refuted by Johannsen. Morgan called out the problem of goal-post-shifting when he wrote that “Modern zoologists who claim that the Darwinian theory is sufficiently broad to include the idea of the survival of definite variations seem inclined to forget that Darwin examined this possibility and rejected it.” (Morgan, 1904).

The early geneticists did not reject what we would call “selection” today, e.g., Morgan (1916), in his closing summary, writes that “Evolution has taken place by the incorporation into the race of those mutations that are beneficial to the life and reproduction of the organism” (p. 194). Bateson, Punnett, de Vries and Johannsen were the other early geneticists most well known for their views on evolution. Johannsen and de Vries both carried out successful selection experiments. de Vries begins his major 1905 English treatise by writing that …

“Darwin discovered the great principle which rules the evolution of organisms. It is the principle of natural selection. It is the sifting out of all organisms of minor worth through the struggle for life. It is only a sieve, and not a force of nature” (p. 6)

In Materials for the Study of VariationBateson (1894) refers to natural selection as “obviously” a “true cause” (p. 5). Punnett (1905) explains that mutations are heritable while environmental fluctuations are not, concluding that “Evolution takes place through the action of selection on these mutations” (p. 53).

Morgan called out the problem of goal-post-shifting when he wrote that “Modern zoologists who claim that the Darwinian theory is sufficiently broad to include the idea of the survival of definite variations seem inclined to forget that Darwin examined this possibility and rejected it.” (Morgan, 1904).

The views of these influential scientists, and their contributions to evolutionary thinking, were not secrets: they were published, cited and discussed. Bateson, Punnett, Morgan and de Vries all were awarded the Royal Society Darwin medal in the period from 1900 to 1930. That is, the Mutationism Story is not just a wildly distorted version of history: it is a wildly distorted version of history contradicted by sources that are readily accessible to any serious scholar. The ongoing success of this kind of mythology is a testament to the power of propaganda and to the insularity of the Synthesis tribal culture (again, see the conceptual immune system).

Explanatory or methodological mutationism

Explanatory and methodological versions of mutationism are useful to contemplate, by comparison to the flavors of adaptationism identified by Godfrey Smith (2001):

  • Empirical adaptationism is ontological, based on a belief about how the world actually is: living things are pervasively adapted, down to the finest detail, and therefore, we will see adaptation everywhere we look because adaptation is in fact everywhere we look, and the explanation for traits will inevitably be functional because traits are in fact inevitably functional.
  • Methodological adaptationism holds that, even though adaptation might not be pervasive, it is the thing we are uniquely equipped to study using the methods of science. This view tends to travel together with the ideology that evolution is a combination of selection and “chance”, with the latter being hard to study systematically.
  • Explanatory adaptationism is the view that, although selection might not be everything, and although we might be able to study other kinds of causes in evolution, a focus on selection and adaptation is justified because adaptation is the distinctive problem in evolution, and selection is the necessary principle behind adaptation.

Analogously, we can imagine empirical, explanatory, and methodological versions of mutationism. The lucky mutant view mentioned below is one possible ontological or empirical flavor of mutationism. In methodological mutationism, which is clearly a research program in evo-devo, we focus on identifying the mutational-developmental changes involved in evolution on the grounds that this is a distinctively reliable and productive way to study evolution. In explanatory mutationism, our focus is on identifying the detailed mutational-developmental changes underlying changes in form, because explaining changes in form over time is the distinctive challenge of evolutionary biology.

Clearly we can study the evolution of form from a structuralist viewpoint as a series of transformations based on genetic encodings and the intrinsic self-organizing properties of material systems, but we also can study the evolution of form from an adaptationist perspective.

Bateson’s early work exemplifies methodological mutationism: he believed that, in order to understand how evolution happens, the first step was to study variations. Accordingly, his Materials for the Study of Variation is a catalog of 886 numbered cases of discontinuous variations. Bateson planned a second volume on continuous variation but subsequent work on quantitative trait distributions made this unnecessary.

Bateson’s approach was observational, but today we see various experimentally oriented mutationist projects in evolutionary biology:

  • attempts to reconstruct mutational changes involved in key changes in development, in the context of evo-devo
  • systematic measurements of M in quantitative genetics, e.g., Houle, et al (2017)
  • reconstructing ancestral protein molecules and their mutants in order to reconstruct the path of history and test hypotheses (from biochemically-oriented molecular evolutionists, e.g., Dean, Weinreich, Thornton, et al)
  • the recent focus on using deep sequencing methods to characterize the mutation spectrum in quantitative detail in a variety of organisms, and in the context of cancer biogenesis

Note that these projects are generally situated in paradigms that are not focused solely on mutation, but also reflect functionalist concerns. This is clearly true of evo-devo, for instance, as the analysis of Novick (2023) makes clear. The evo-devoists are not merely concerned with understanding why certain types of transformations are mutationally and developmentally likely, they are also concerned with selection and function. The same is obviously true of the line of work from Thornton and colleagues, which combines the reconstruction of mutants with functional assays and even selection experiments. In the study of cancer drivers and clonal haematopoesis mutants, contemporary research on mutation spectra, mutation rates, and repair mutants is premised on the understanding that clinical prevalence reflects both the rate of mutational origin and the selection intensity (figure; see Cannataro, et al. 2019; Watson and Blundell, 2022).

Estimates of selection intensity (left) and rate of mutation (right) for clonal haematopoesis lineages from Watson and Blundell (2022). Yes, there is a negative correlation. Why values of s and u might be negatively correlated (in the distribution after mutation and selection) is a question addressed in Gitschlag, et al (2023).

If we look at methodological mutationism as an extreme or exclusive position, it is difficult to separate from an extreme form of skepticism about selection that seems unwarranted today, when we can test hypotheses of selection in rigorous ways and assign some non-negligible proportion of the variance in outcomes to selection. Apropos, Nei (2013) does not reject selection as a causal principle in evolution, yet in practice, he seems to reject every attempt to attribute something concrete to positive selection. His approach recalls the attitude of Bateson, who (a century earlier) disparaged adaptationist story-telling by appealing to Voltaire’s Dr. Pangloss, a trope made famous in the “Panglossian paradigm” of Gould and Lewontin (1979). A scientist in Bateson’s time might find it easy to dismiss the vast majority of claims about selection as armchair speculation, not science. Punnett was so deeply skeptical of adaptive explanations that he rejected adaptive mimicry as an explanation for apparently mimetic morphs in butterflies!

Likewise, it’s hard to think of explanatory mutationism as an exclusive position. Clearly we can study the evolution of form from a structuralist viewpoint as a series of transformations based on genetic encodings and the intrinsic self-organizing properties of material systems, but we also can study the evolution of form from an adaptationist perspective.

So, rather than supposing that mutationism is uniquely explanatory for evolution in general, perhaps we can suppose instead that it is distinctively explanatory in some limited but important context. What is the limited but important context in which selective explanations are the least informative or trustworthy, and in which mutational explanations have more power to explain what we wish to understand? I think the best answer here is that there are some aspects of deep divergence, such as the formation of new body plans, major taxa, or key innovations, in which the power of selective explanations is at its lowest—because there are too many degrees of freedom— and the power of mutational explanations are at their highest, e.g., when key innovations can be associated with specific changes in developmental genetics, against a background of conserved features that do not change.

Mendelo-mutationism as a school of thought

The “school of thought” version of Mendelian mutationism is not a unified theory, but a loose collection of beliefs and ideas, overlapping substantially with how the “Modern Synthesis” is construed mistakenly today as a loose collection of beliefs consistent with genetics and selection (see this blog or Stoltzfus and Cable, 2014 for a review).

The early geneticists were the first scientists to accept particulate inheritance and mutation as the foundation of their understanding of evolution, in the sense that they viewed with suspicion any idea that could not be reconciled with particulate inheritance and mutation. Adopting genetics as the foundation for evolutionary reasoning sounds very familiar today, but in 1909 this was a disruptive view that seems to have pissed off evolutionists who were not geneticists, i.e., most of them. Imagine these upstarts telling leading evolutionary thinkers— paleontologists, systematics, embryologists— that the foundation for all thinking in evolution must be particulate inheritance and mutation, new discoveries only understood by a small group of scientists!

As noted above, Bateson and Saunders (1902) clearly articulated the research program of looking for deviations from Hardy-Weinberg expectations as a way of detecting causes other than inheritance.

In the same 1902 paper, they explain what became known as “the multiple factor theory” in which a smooth distribution of trait-values reflects, not blending inheritance and fluctuation, but the joint effect of Mendelian variation at many loci, combined with environmental noise.

Adopting genetics as the foundation for evolutionary reasoning sounds very familiar today, but in 1909 this was a disruptive view that seems to have pissed off evolutionists who were not geneticists, i.e., most of them.

But of course they also considered non-gradual changes via distinctive mutations, i.e., saltations. To the extent that non-gradual changes reflecting distinctive mutations are important in evolution, understanding evolution requires knowing how and when these distinctive mutations arise, based on relevant theories and systematic data. This is why Bateson (1894) catalogued distinctive variations as a way of understanding evolution. Morgan later made a systematic search for mutations in fruit-flies. It was Morgan who first clearly depicted evolution as a series of mutations that are accepted by virtue of being beneficial to the survival of the species. He articulated the concept of a probability of fixation in 1916, distinguishing the case of beneficial, neutral and deleterious mutations (the mathematical problem was later solved partially by Haldane, 1927 and more thoroughly by Kimura, 1962).

Interestingly, it was also Morgan (1909) who first suggested the randomness of mutation as a kind of metaphysical gambit, a working assumption that, so long as the origins of mutations remain a mystery, we will treat them as random and not entertain any ideas in which they have special properties.

Whether definite variations are by chance useful, or whether they are purposeful are the contrasting views of modern speculation. The philosophic zoologist of to-day has made his choice. He has chosen undirected variations as furnishing the materials for natural selection. It gives him a working hypothesis that calls in no unknown agencies; it accords with what he observes in nature; it promises the largest rewards. He does not deny, if he is cautious, the possibility that there may be a purposefulness in the sense that organisms may respond adaptively at times to external conditions; for the very basis of his theory rests on the assumption that such variations do occur. But he is inclined to question the assumption that adaptive variations arise because of their adaptiveness. In his experience he finds little evidence for this belief, and he finds much that is opposed to it. He can foresee that to admit it for that all important group of facts, where adjustments arise through the adaptation of individuals to each other—of host to parasite, of hunter to hunted—will land him in a mire of unverifiable speculation. 

Note again the stark contrast between the facts of history and the stories used in Synthesis gatekeeping, in which an association of “mutationism” with directed mutation has been fabricated repeatedly in the attempt to discredit both (Gardner, 2013; Svensson, 2023).

However, Morgan frequently noted that mutations happen at different rates. He and Punnett both believed that this was important for evolution, and might play a role in parallel evolution, citing cases like albino or melanic forms. Under a neo-Darwinian view, melanic forms are expected to emerge gradually, like the all-black rats in Castle’s experiments, from the gradual accumulation of many small differences; and the repeated appearance of melanism in different taxa would indicate that it is some kind of adaptive optimum. For the mutationists, the repeated occurrence of melanic forms suggested that such forms were readily mutationally accessible.

Vavilov (1922) took this idea of parallel evolution by parallel variations to extreme lengths. From his extensive observations of plants, especially crop species, he developed a theory that each major group of organisms has a set of characteristic variants that eventually manifest as distinct species, e.g., if family F has a tendency to produce long-eared forms, this tendency would manifest in genera G1, G2, … each having both long-eared and short-eared species within the genus. He also proposed a kind of mimicry— now called Vavilovian mimicry— that turns out to be quite important among domesticated crop species. In Vavilovian mimicry, the model is a cultivated species actively harvested and propagated by humans, and the mimic starts out as a weed that is eventually propagated by humans by virtue of mimicking the model in terms of the time of maturation, and similar responses to threshing and winnowing techniques. For instance, rye and oats are believed to be Vavilovian mimics that emerged in the context of wheat cultivation (see the wikipedia article on Vavilovian mimicry).

With regard to species and speciation, the early geneticists tended to believe that reproductive incompatibilities were “the true criterion of what constitutes a species”  (Punnett, 1911, p. 151).  With the Modern Synthesis, this “biological species concept” became the prevailing view (Mallet 2013). They allowed for different kinds of speciation, including speciation by non-Mendelian mutations like de Vriesian macromutations, but also by the accumulation of what we now call “Bateson-Dobzhansky-Muller” incompatibilities.

To summarize, the early geneticists opened up and explored a new field, considering a wide range of possibilities (excluding only Lamarckism) and contributing a number of key concepts to evolutionary genetics. Few people know of their accomplishments today because, in Synthesis Historiography, scientific progress only comes from people with the right Darwinian lineage, and not from critics of neo-Darwinism, who are treated as aliens or un-persons. For instance, in Synthesis Historiography, the credit for rejecting 19th-century views of heredity and introducing modern notions of hard inheritance is awarded, not to the geneticists responsible for this innovation, but to 19th-century physiologist and infamous mouse-torturer August Weismann. The Oxford Encyclopedia of Evolution does not have biographic entries for Bateson, de Vries, Punnett, or other early geneticists except for the entry on Morgan, which says nothing of his views of evolution, although he wrote 4 books on the topic. For a graphical example of how the early geneticists are treated as un-persons in Synthesis Historiography, read this.

Lucky mutant (sushi conveyor) dynamics

The lucky mutant version of mutationism is a focus on the regime of population genetics in which origination events are important, so that the timing and character of evolutionary change depend on the timing and character of events of mutation that introduce new alleles (or phenotypes). This is sometimes called “mutation-driven” or “mutation-limited” evolution. For me, “mutation-driven” evokes evolution by mutation pressure, so I don’t like the term, but I feel obliged to use it occasionally because this is what some readers recognize. The problem with “mutation-limited” is that, for the vast majority of readers, it suggests some kind of limit to the outcomes that selection can access, whereas for theoreticians this is a statement about dynamics.[3]

As a technical description of dynamics, “mutation-limited” behavior could mean either (1) behavior responsive to changes in u or (2) the limiting behavior as u approaches 0, which is origin-fixation dynamics. When people like Dawkins (2007) invoke the idea that “evolution is not mutation-limited” as a way of discounting a focus on mutation, this only makes sense if it means that evolutionary behavior is not responsive to changes in u, which is what Dobzhansky and others stated explicitly, i.e., they said that changing the rate of mutation would not change the rate of evolution due to the buffering capacity of the gene-pool.

In other words, the most direct label for mutation-responsive dynamics would be “mutation-responsive dynamics” rather than “mutation-limited” or “mutation-driven” dynamics. I have also referred to the “sushi-conveyor” regime of population genetics, as distinct from the “buffet” regime.

Defining “mutationism” as a position on population genetics is not the most historically justifiable way to interpret the views of the early geneticists, because they were not very explicit about population genetics. However, it is how we might choose to see mutationism in retrospective contrast to the neo-Darwinian view of the Modern Synthesis. Darwin’s followers, in their dialectical encounter with the early geneticists, were most concerned to defend the power and creativity of selection, to defend gradualism, and to reject a lucky mutant view of dynamics. They did this by invoking the “buffet” regime of population genetics, in which evolution takes place by shifting the frequencies of alleles present in an abundant gene pool.

The sushi conveyor: We iteratively make a yes-or-no choice on the chef’s latest creation as it passes by on a moving conveyor. A bias in the rate of appearance directly biases the outcome.

Consider again the example of melanic or albino morphs. The repeated occurrence of melanic morphs in related species might suggest to us the possibility of a common mutation to blackness that has occurred repeatedly. Under neo-Darwinism, by contrast, this would only happen by the accumulation of many small effects, i.e., in the same way that all-black rats emerged in the Castle experiment from the accumulation of many small variations. Note that the historic reception of Castle’s experiment illustrated the breadth of mutationist thinking: in a famous dispute with Castle and colleagues, members of Morgan’s group insisted that the gradual emergence of all black and all white rats was entirely consistent with incremental frequency shifts of small-effect alleles under the Mendelian multiple-factor theory, and did not require blending or transformation of hereditary factors, as Castle (under the influence of Darwin’s thinking) had argued.

If “mutationism” means the lucky-mutant view of sushi-conveyor dynamics, then we have seen a broad resurgence of mutationism in evolutionary biology, starting with the molecular evolutionists in the 1960s. See The shift to mutationism is documented in our language.

A transition to …

Finally we can think of mutationism not as a resting point or destination, but as an unstable transition-state on the path to something else. The most productive line of thought, perhaps, is that it points the way toward a paradigm of dual causation that combines functionalism and structuralism, with a major goal of partitioning variance in outcomes to variational and selective causes. A clear and direct recognition of dual causation is evident in statements of Vavilov (1922), e.g.,

“the role of natural selection in this case is quite clear.  Man unconsciously, year after year, by his sorting machines, separated varieties of vetches similar to lentils in size and form of seeds, and ripening simultaneously with lentils.  The same varieties certainly existed long before selection itself, and the appearance of their series [i.e., combinations], irrespective of any selection, was in accordance with the laws of variation.” (p. 85)

Here Vavilov combines two different kinds of dispositions in one theory, such that each disposition reflects a set of distinct causal processes that are invoked directly in historical explanations. Darwin’s followers would look at the same case and say that variation merely supplies raw material that selection shapes into adaptations, invoking two kinds of causal processes, only one of which is dispositional.

One sees a notion of dual causation expressed very abstractly by Vrba and Eldredge (1984), in their enhanced description of evo-devo thinking:

“Developmental biologists variously stress: (1) how indirect any genetic control is during certain stages of epigenesis; (2) that the system determines by downward causation which genomic constituents are stored in unexpressed form versus those which are expressed in the phenoytpe; (3) that bias in the introduction of phenotypic variation may be more important to directional phenotypic evolution than sorting by selection.  This is in contrast to the synthesis, which stresses more or less direct upward causation from random mutations to phenotypic variants, with selection among the latter as the prime determinant of directional evolution.”

Instead of casting evolution as shifting gene frequencies, we can depict it more broadly as a process of the introduction and reproductive sorting of variation in a hierarchy of reproducing entities.[4] To the extent that evolution has any predictable tendencies, they reflect biases in introduction and biases in sorting. This is not simply a re-statement of the position of Vavilov or of Vrba and Eldredge, which is not based on any technical understanding of bias in the introduction of variation as a population-genetic mechanism.

However, the reason for the resurgence of interest in quasi-mutationist thinking— as an attempt to get beyond neo-Darwinism— is that selection does not actually govern evolution in the way that neo-Darwinism supposes. It is a directional factor, but not the directional factor.

The classical functionalist position of neo-Darwinism and the Modern Synthesis focuses on biases in reproductive sorting (i.e., selection) as the cause of everything interesting. The success of this research program is proof that effects of biases in reproductive sorting are profoundly important in evolution. However, the reason for the resurgence of interest in quasi-mutationist thinking— as an attempt to get beyond neo-Darwinism— is that selection does not actually govern evolution in the way that neo-Darwinism supposes. Selection is a directional factor, but not the directional factor. We can also pursue a research program based on the role of generative biases in evolution and, even more broadly, a research program that focuses on both biases in the introduction of variation and biases in the reproduction of variation, with the goal of quantifying their relative influence on the predictability of evolution.

References

Bateson W. 1894. Materials for the Study of Variation, Treated with Especial Regard to Discontinuity in the Origin of Species. London: Macmillan.

Bateson W, Saunders ER. 1902. Experimental Studies in the Physiology of Heredity. In. Reports to the Evolution Committee: Royal Society.

Davenport CB. 1909. Mutation. In. Fifty Years of Darwinism: Modern Aspects of Evolution. New York: Henry Holt and Company. p. 160-181.

Dawkins R. 2007. Review: The Edge of Evolution. In. International Herald Tribune. Paris. p. 2.

de Vries H. 1905. Species and Varieties: Their Origin by Mutation. Chicago: The Open Court Publishing Company.

Futuyma DJ. 2017. Evolutionary biology today and the call for an extended synthesis. Interface Focus 7:20160145.

Godfrey-Smith P. 2001. Three Kinds of Adaptationism. In:  Orzack SH, Sober E, editors. Adaptationism and Optimality. Cambridge: Cambridge University Press. p. 335-357.

Gould SJ, Lewontin RC. (classic; CNE theory co-authors). 1979. The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist program. Proc. Royal Soc. London B 205:581-598.

McCabe J. 1912. The Story of Evolution.

Morgan TH. 1904. The Origin of Species through Selection Contrasted with their Origin through the Appearance of Definite Variations. Popular Science Monthly:54-65.

Morgan TH. 1909. For Darwin. Popular Science Monthly 74:367-380.

Morgan TH. 1916. A Critique of the Theory of Evolution. Princeton, NJ: Princeton University Press.

Nei M. 2013. Mutation-Driven Evolution: Oxford University Press.

Novick R. 2023. Structure and Function. In. Cambridge: Cambridge University Press.

Poulton EB. 1909. Fifty Years of Darwinism. In. Fifty Years of Darwinism: Modern Aspects of Evolution. New York: Henry Holt and Company. p. 8-56.

Punnett RC. 1905. Mendelism. London: MacMillan and Bowes.

Punnett RC. 1911. Mendelism: MacMillan.

Segerstråle U. 2002. Neo-Darwinism. In:  Pagel M, editor. Encyclopedia of Evolution. New York: Oxford University Press. p. 807-810.

Stamhuis IH. 2015. Why the Rediscoverer Ended up on the Sidelines: Hugo De Vries’s Theory of Inheritance and the Mendelian Laws. Science & Education 24:29-49.

Stoltzfus A, Cable K. 2014. Mendelian-Mutationism: The Forgotten Evolutionary Synthesis. J Hist Biol 47:501-546.

Svensson EI. 2023. The structure of evolutionary theory: beyond Neo-Darwinism, Neo-Lamarckism and biased historical narratives about the Modern Synthesis. In:  Dickins TE, Dickins JA, editors. Evolutionary biology: contemporary and historical reflections upon core theory. Cham, Switzerland: Springer Nature.

Vavilov NI. 1922. The Law of Homologous Series in Variation. J. Heredity 12:47-89.

Vrba ES, Eldredge N. (benchmark; co-authors). 1984. Individuals, hierarchies and processes: towards a more complete evolutionary theory. Paleobiology 10:146-171.

Notes

[1] The term “early geneticist” typically means scientists working on mutation and Mendelian inheritance in the first decade of the 20th century (thus Goldschmidt is not considered an early geneticist). The most influential ones were clearly Johannsen, de Vries, Bateson, Punnett, and Morgan. My claim that leading early geneticists did not use the term “mutationism” for their own views is based on published works of Bateson, Punnett, Morgan and de Vries. I’m not going to say they never used it, but I haven’t found a case. I found one instance where Davenport (1909) refers to the view of the “the mutationist”. De Vries literally proposed a MutationsTheorie so it is natural to call him a mutationist. But de Vries’s thinking was extremely complex and mainly non-Mendelian, and the other early geneticists developed their own views, not relying on de Vries’s thinking (for explanation, see Stoltzfus and Cable, 2014).

[2] I’m saying this as an established researcher who is not trying to get a job or tenure, or to curry favor with decision-makers. If you are a junior person, calling out the strawman arguments and shoddy historical scholarship used by influential gatekeepers poses risks to your career, and you should weigh those risks carefully. It’s perfectly all right to leave this fight to others who are not as vulnerable. We all have to pick our battles, and mine are not the same as yours.

[3] For instance, consider evolution under mutation bias on a smooth landscape with one peak. Ultimately the system goes to the peak: mutation places no limits in this sense. However, the rate and trajectory of the approach to the peak will reflect the rate and bias of mutations. So, the dynamics are mutation-responsive but the ultimate outcome and the ultimate level of fitness or adaptation is not limited by mutation. If multiple peaks or destinations are possible, then biases in introduction may be influential. Calling this mutation-limited evolution would just confuse people; saying that it isn’t mutation-limited also would give the wrong impression.

[4] Technically the list should be something more like “introduction, hereditary transmission and reproductive sorting” with biases possible in each process. Biased gene conversion is a transmission bias. So is meiotic drive. Effects of mutational hazard in the thinking of Lynch can be understood as biases in transmission, i.e., longer sequences have lower transmission due to mutational damage (mutational hazard is not an effect of introduction; although it is possible to cast it as a form of selection, that is weird IMHO).

The buffet and the sushi conveyor

The return of mutationism to mainstream evolutionary biology is evident in the way mainstream articles now describe the role of mutation in evolution, in our reliance on mathematical models that evoke a mutationist view, and in evo-devo research programs that focus on identifying causative major-effect mutations.

This shift has happened in a kind of sub-conscious way, without commentary or reflection.  I’ll comment below on the reasons for that.

My main purpose here is to contrast way that the neo-Darwinian and mutationist views refer implicitly to two different regimes of population genetics evoked in two styles of self-service restaurant: the buffet and the sushi conveyor.

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Why size matters: Saltationism, creativity, and the reign of the DiNOs

Debates on “gradualism” in evolutionary biology address the size distribution of evolutionary changes.  The classical Darwinian position, better described as “infinitesimalism”, holds that evolutionary change is smooth in the sense of being composed of an abundance of infinitesimals (not one infinitesimal at a time, but a blending flow of infinitesimals).   The alternative is that evolution sometimes involves “saltations” or jumps, i.e., distinctive and discrete steps.  The dispute between these two positions has been a subject of acrimony at various times in the 20th century, with several minor skirmishes, and a larger battle with at least one genuine casualty (image).

Walter Frank Rafael Weldon (public domain image from wikipedia). Legend has it that Weldon ignored an advancing illness and worked himself to death trying to disprove the relevance of Mendelism in natural inheritance.

Walter Frank Rafael Weldon (public domain image from wikipedia).  Weldon ignored an advancing illness and worked himself to death (1906) poring over breeding records in an attempt to cast doubt on discrete inheritance.  Along with Pearson and other “biometricians”, Weldon held to Darwin’s non-Mendelian view combining gradual hereditary fluctuations with blending inheritance.

Today, over a decade into the 21st century, we have abundant evidence for saltations, yet the term is virtually unknown, and we still seem to invoke selection under the assumption of gradualism.  Are we saltationists, or not?  I’m going to offer 3 answers below.

But first, we need to review why the issue is important for evolutionary theory.

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Mendelian-Mutationism: the Forgotten Evolutionary Synthesis

What is Mendelian-mutationism?  And why do we argue in a recent paper in that it represents a forgotten evolutionary synthesis (Stoltzfus and Cable, 2014, Mendelian-Mutationism: The Forgotten Evolutionary Synthesis. J Hist Biol. doi:10.1007/s10739-014-9383-2)?

ys01-popsize
Effect of mutation bias in the 1-step adaptation model of Yampolsky & Stoltzfus, 2001. The greater the bias in mutation, the greater the tendency to evolve in the mutationally favored direction.

For me, the story started a long time ago with our theoretical demonstration (graph at right) that bias in the introduction of variation (by mutation-and-altered-development) is a fundamental cause of non-randomness in evolution (Yampolsky & Stoltzfus, 2001).

The novelty of this claim bothered me deeply.  Why?  Here was a basic principle— a causal link between non-randomness in biological inputs (mutational and developmental biases) and non-randomness in evolutionary outputs— as fundamental as the concept of selection or drift.  Yet, this principle was not mentioned in any textbook of evolution or population genetics (indeed, there is even a classical population-genetic argument against a determinative role for mutational biases).  I could not even find this principle in the research literature!  When it comes to contemplating the impact of biases in variation, evolutionary biologists habitually assume that such an impact is impossible, except in the special case of (1) rigid constraints (i.e., the impossibility of generating form B means we’ll get A or C instead), or (2) neutral evolution.   We knew that all of this was incorrect.

This prompted 2 questions.  Why wasn’t a general connection between biases in variation and biases in evolution recognized long ago, e.g., by Wright, Haldane or Fisher?   And, why— after it was discovered and published in 2001— didn’t this inspire a revolution?

bookshelf
The top of my evolution bookshelf, with historic works in roughly chronological order: from Darwin and Mivart to the Mendelians (top shelf), then the core of the Modern Synthesis, up to the early molecular era (next shelf) [1]

I’m still puzzling over the second, admittedly naive, question.  To address the first question, I’ve spent an inordinate amount of time studying the development of evolutionary thought (bookshelf at right).

The short answer is this: the notion that mutation has a dispositional role in evolution, influencing its rate and direction, represents a kind of “internal” causation, an internal source of direction in evolution, that Darwin’s followers rejected as illegitimate.  Ever since, it has been a blind spot in evolutionary thinking.

The nature of this rejection is hard to comprehend today, due to a process of amnesia and theory-drift.  Nearly all evolutionary biologists today believe that evolutionary biology has a prevailing theory, and that this theory— called the Modern Synthesis or modern neo-Darwinism— came together in the mid-20th century.   What few realize is how far the common conception of this theory has drifted from its original intentions.  The original Modern Synthesis was held together with Darwinian doctrines that most scientists today do not accept, such as the doctrine of gradualism, the idea that selection is creative, or the rejection of any internal causes of direction.  We can think of these as the “soft parts” of the Modern Synthesis, the muscles and connective tissue that gave it shape and motion.

whale-bones
The soft bits of this whale carcass rotted away, leaving only the bones.

Over time, the Darwinian character of the Modern Synthesis has rotted away, leaving only the more resilient parts.  This is why scientists today think of the Modern Synthesis as a kind of open-ended framework for understanding evolution. They are looking at an open-ended skeleton.

Our study of early geneticists revealed that this skeleton predates the Modern Synthesis.  There was an earlier Mendelian-Mutationist Synthesis that combined mutation, heredity and selection, without Darwinian doctrinal commitments to gradualism, the creativity of selection, and the “randomness” (non-importance) of mutation.  What most scientists today think of as the Modern Synthesis is actually the forgotten Mendelian-Mutationist synthesis. Like scientists today, the early geneticists or “mutationists” welcomed both selection and neutrality, allowed both gradual change and saltations, and welcomed the idea that biases in mutation could be the cause of parallelisms or trends.

The new paper by Stoltzfus and Cable describes what the early geneticists believed about how evolution works, and what they contributed to the foundations of evolutionary thought.  It also explains why they rejected Darwin’s theory (another case in which the popular conception of a theory today does not match what its historical meaning).

But that’s only half of the story.  The other big theme is historiography, the telling of history.  The disconnect between what actually happened and what scientists believe is not just a matter of theory-drift.

“History is written by the victors,” Churchill said.  In this case, the victorious architects of the Modern Synthesis promulgated a view of early geneticists as bumbling fools who saw mutation and selection as opposing principles, and who couldn’t think synthetically.  The period of 1900 to 1920, actually a rich period in which early geneticists laid the foundations of modern evolutionary thought, is described perversely as part of an “eclipse of Darwinism”— a period of darkness when the world was deprived of His light— lasting until Darwinism is re-born in the Modern Synthesis.  This story-telling has been so influential that, when contemporary scientists list historically important figures, all key figures of the Mendelian-Mutationist synthesis are removed, Soviet-style (see figure below).[2]

evotmline_with_box
On this timeline of “notable people who have contributed to evolutionary thought” (source), I have super-imposed a salmon-colored box. This box includes the birth year of anyone 25 to 60 years old— the prime of a scientist’s life—  when genetics was discovered in 1900.  No timelines begin in the box. That is, the figure tells us there were no notable contributions by scientists born in this period, which includes the birth of de Vries (1848-1935), Johannsen (1857-1927), Bateson (1861-1926), Cuénot (1866-1951), Davenport (1866-1944), Morgan (1866-1945), and Punnett (1875-1967). Richard Goldschmidt (1878-1958), born just a few years later and listed as a non-Darwinian (top), was a second-generation mutationist whose 1940 book introduced “hopeful monsters” and provoked Ernst Mayr into writing a book of his own.

That is, the distorted view of history that evolutionary biologists hold today is not just a matter of passive amnesia, but of a highly successful public relations campaign, what evo-devoist Stuart Newman recently called “an unremitting 90-year campaign to identify ‘evolutionary theory’ with ‘Darwinism'”.

The recent paper on Mendelian-Mutationism is actually an off-shoot of a series of “Mutationism myth” blogs written for SandWalk in 2010.  To turn the blogs into a scholarly work worthy of publication in a peer-reviewed historical journal was a major project accomplished over the course of 2 years, by teaming up with a history-of-science graduate student named Kele Cable. Kele recently blogged about our paper on his web site.

Notes

[1] Some of my favorites: Haldane, 1932 (the tattered volume, top, second from right); the 1911 (3rd) edition of Punnett’s Mendelism, the first textbook of genetics (the slimmer of two burgundy volumes, top center); George Williams (1966) Adaptation and Natural Selection (row 2, 9th from right, with the shiny jacket cover); Lewontin, 1974 (row 2, right end, red with gold lettering next to Crow & Kimura 1970).

[2] Other examples could be given.  The Oxford Encyclopedia of Evolution (click for searchable online index) has an entry for Mendel, who made no direct contributions to evolutionary thinking, but lacks an entry for all of the mutationists except for Morgan.  Importantly, the entry for Morgan says nothing of his evolutionary views, only of his contributions to genetics.  Textbooks (e.g., Ridley, 1993, or Freeman & Herron, 1998) and online teaching materials (try a web search on “development” or “history”  of evolutionary thought) frequently jump from Darwin to the Modern Synthesis, with the explanation that Darwin’s theory was right but needed a mechanism, and this was supplied when the architects of the Modern Synthesis combined genetics and selection.  Early geneticists, if they are mentioned at all, are depicted only for their alleged failure to understand selection, accept small changes, or achieve synthesis.

When “Darwinian adaptation” is neither

Getting stuff right

Early in the evolution of the Sequence Ontology, it was noted (by gadflies like myself) that SO asserts the relationship of mRNA to gene to be the “part of” relationship.  This is obviously wrong.  An RNA molecule is not part of a DNA molecule.   Saying that mRNA is part of a gene is like saying that a CD with some audio chapters from a book is part of that book.

Ontologies are supposed to support formal reasoning: errors in representation will lead inevitably to erroneous results.  For instance, if we are reasoning about the chemical composition of a cell using mRNA part_of gene as a constraint, we would conclude falsely that the mass of DNA must always be at least as much as the mass of mRNA, because the mass of a thing is always at least as great as the mass of some specified parts.

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The Mutationism Myth (1): The Monk’s Lost Code and the Great Confusion

This is the first in a series of blogs first published in 2010 on Sandwalk.

The mutationism myth tells the story of how, just over a century ago, the scientific community responded to the discovery of Mendelian genetics by discarding Darwinism, and how Darwinism subsequently was restored.  In this, the first of six parts, we are not going to confront any tough scientific or conceptual issues. Instead, we are just going to review an odd story about our intellectual history.

The Mutationism Story

While “myth” has the connotation of falsehood, the story that a myth tells isn’t necessarily a false one. The mutationism myth, at least, is anchored in historical events.1

The mutationism myth tells the story of how, just over a century ago, the scientific community responded to the discovery of Mendelian genetics by discarding Darwinism, and how Darwinism subsequently was restored. The villains of the story are the influential early geneticists or “Mendelians” who saw genetics as a refutation of Darwinism; the heroes are first, the founders of population genetics, theoreticians who sorted everything out in favor of Darwinism by about 1930, and second, the architects of the Modern Synthesis, activists who popularized and institutionalized what we’re calling “Darwinism 2.0”.

This story has been re-told in secondary sources for nearly 50 years, though I sense that the frequency is decreasing as this episode passes into ancient history. To find examples, try looking up “mutationism” (sometimes “Mendelism” or even “saltationism”) in the index of a book about evolution.

I encourage you to consult whatever sources you have and to share the stories that you find. Note that you won’t always be successful. A quick survey of several dozen contemporary books on my shelf reveals that most don’t address this episode specifically (a notable absence, in some cases 2); some tell the mutationism myth with varying degrees of panache; and a few provide a historical account rather than a myth. The few historical accounts that I found were in Gould’s 2002 The Structure of Evolutionary Theory, Strickberger’s 1990 textbook Evolution, and the Wikipedia entry on “Mutationism”.

Sample stories

Lets look at a few examples of the mutationism story. Readers who want to check out a freely available online source from the scholarly literature may refer to Ayala and Fitch, 1997 (http://www.ncbi.nlm.nih.gov/pubmed/9223250?dopt=Citation). One example that really caught my eye is not from scientific literature, but from the 2005 obituary for Ernst Mayr in The Economist:

It was not that biologists had given up on evolution by the 1940s-quite the contrary. But they had got very confused about its mechanism. . . . The geneticists of the early 20th century did not help. They rediscovered the laws of inheritance first developed 40 years earlier by Gregor Mendel, an unsung Moravian monk. They also discovered the idea of genetic mutation. But instead of linking these things to natural selection, they came up with the idea of “saltation”-in other words, sudden mutational shifts from one well-adapted species to another. Nor, the geneticists complained, had there been enough time for natural selection to do its work, given what they had discovered about the rate at which mutations occur, and the fact that most mutations are deleterious. It was all a bit of a mess. . .Mr Mayr’s advantage over the laboratory-bound biologists who had hijacked and diluted Darwin’s legacy was that, like Darwin, he was a naturalist-and a good one. (anonymous, 2005)

Of course, this is a magazine article, written by anonymous staff writers– typically one doesn’t see such florid language in the scholarly literature. But did the staff writers of the Economist (representing elite opinion) really originate this story, based on their own personal recollections of the 1930’s? Of course not. Mayr himself popularized the image of geneticists as laboratory-bound geeks lacking the organic insight of “naturalists”. This disdain for the geneticists who “hijacked” Darwin’s legacy is readily apparent when evolutionary writers depict geneticists as fools holding “beliefs” that have “obvious inadequacies”, unable to understand or “grasp” their own scientific findings:

“It is hard for us to comprehend but, in the early years of this century when the phenomenon of mutation was first named, it was regarded not as a necessary part of Darwinian theory but as an alternative theory of evolution! There was a school of geneticists called the mutationists, which included such famous names as Hugo de Vries and William Bateson among the early rediscoverers of Mendel’s principles of heredity, Wilhelm Johannsen the inventor of the word gene, and Thomas Hunt Morgan the father of the chromosome theory of heredity. . . Mendelian genetics was thought of, not as the central plank of Darwinism that it is today, but as antithetical to Darwinism. . . It is extremely hard for the modern mind to respond to this idea with anything but mirth” (Dawkins, 1987, p. 305)

“According to mutationism, random changes in the hereditary material are sufficient for adaptation without much, or any, selection at all. Mutations just somehow happen to be adaptive, the right changes simply manage to occur. The inadequacies of this view are obvious” (Cronin, 1991, p. 47).

“Darwin knew nothing of this [i.e., genetics] but as it turned out, his ignorance was sublimely irrelevant to the problem he was really interested in tackling: evolution. This point was not fully grasped by biologists. Many early geneticists at the dawn of the 20th century, thought their discoveries of the fundamental principles of genetics somehow cast doubt [on], or rendered obsolete, the concept of natural selection. It took several decades of experimentation and theoretical (including mathematical) analysis to show not only that there was no conflict inherent between the emerging results of genetics and the older Darwinian notion of natural selection, but that the two operate in different domains.” (Eldredge, 2001, p. 67)

“Mendelian particulate inheritance (today, we call the “particles” genes) was originally identified with De Vries’s “mutation theory”, according to which new variations or species originated in large jumps, or macromutations, and evolution was exclusively explained by mutation pressure. Darwinian naturalists, believing that Mendelism was synonymous with mutation theory, held on to theories of soft inheritance, while they considered selection a weak force at best. They did not know of the new findings in genetics that would have supported Darwinism. (SegerstrŒle, 2002)

Notice how, in every version of the story above, the position taken by early geneticists just doesn’t make sense. This isn’t a story of theory versus theory, its a story of confusion ultimately yielding to reason.

If de Vries and the other geneticists are playing the role of the pied piper in this story, the “naturalists” are like the children lured away from their Darwinian home. Ultimately the innocents are returned, and order restored, by mathematicians:

“Between 1918 and 1932 Fisher, Haldane, and Wright showed that Mendelian genetics is consistent with natural selection. Only then, more than 60 years after the publication of The Origin of Species, was the genetic objection to natural selection finally removed. Modern molecular and developmental genetics have confirmed in exquisite chemical detail the key aspects of genetics necessary for Darwin’s ideas to work: that the genetic material is DNA, that DNA has a sequence, . . . mutates . . . contains information . . ” (p. 16 of Stearns and Hoekstra, 2005)

One might have thought that the compatibility of genetics and selection was obvious from the start, or that it had been demonstrated by the selection experiments of Johannsen, but apparently biologists of the time had a high demand for mathematical rigor.

Anatomy of a Myth

In a subsequent post, we will look at original sources to see what the “mutationists” actually believed, and why. And eventually we will integrate this into the bigger picture of how evolutionary theory developed. But for now, lets just summarize the pattern that is apparent in the literature.

First, the mutationism story is clearly a story or myth, and not an ordinary scientific truth claim. We can see this because the story-tellers are not using ordinary scientific conventions to convince us that the story is true. If you or I were making an ordinary scientific argument (for instance) for an effect of “translational selection” on codon usage, we would mention a correlation between codon frequencies and the abundance of corresponding tRNAs, citing the classic work of Ikemura (1981), and we might even repeat a figure showing this correlation, to impress this point upon the minds of readers (e.g., just as in Ch. 7 of Freeman & Herron, 1998).

When I see instances of the mutationism story, typically I don’t find quotations illustrating what the mutationists believed, nor facts & figures to refute their views, but only vague attributions and generalized claims. Apropos, the following quotation from Ernst Mayr never fails to make me laugh:

The genetic work of the last four decades has refuted mutationism (saltationism) so thoroughly that it is not necessary to repeat once more all the genetic evidence against it. (Mayr, 1960)

And the puissant Dr. Mayr proceeds on, not boring the reader with any tiresome “genetic evidence”, nor citing sources that might allow the reader to evaluate the truth of his statement. Its a story, after all.

By contrast, the 3 sources that I mentioned above as providing scientific history, rather than myth, all make reference to specific experimental and theoretical results, and reveal knowledge of specific historically important scientific works. For instance, Strickberger’s reference list includes Johannsen, 1903, as well as the 1902 paper by Yule that reconciled Mendelian genetics with quantitative variation (in neo-Darwinian mythology, credit for Yule’s work is given to little Ronny Fisher, who was 11 at the time).

Second, every story has a plot or “action”, and the main action of the mutationism story is a turn of fate in which power is temporarily in the hands of the wrong people or ideas. In archetypal terms, its a story of usurpation and restoration: the throne is usurped, and the kingdom falls into darkness and confusion until the throne is restored to the king’s rightful heirs. The mutationism episode didn’t have to be told that way: it might have been presented as a period of reform (in which old ideas were abandoned) or discovery (when new territory was mapped out). Instead, its presented as a mistake, an interlude of confusion, a collective delusion.

Indeed, another way to look at the mythic action is that the Mendelians are wizards or false prophets who place the kingdom under a spell, leading folks astray and causing them to believe things that they just shouldn’t have believed.

What delusional spell did the Mendelians cast? In the story by Eldredge, or by Stearns & Hoekstra above, the spell is that Mendelian genetics is inconsistent with “the concept of natural selection” (Eldredge). In the story told by SegerstrŒle, Cronin, Mayr and The Economist, the delusional spell is a bit different: the principle of selection is irrelevant because mutational jumps alone explain evolution.

Third, the key to restoring Darwin’s kingdom was to add the missing piece of genetics. Ultimately, after the period of darkness ended, the discovery of genetics “provided the missing link in Darwin’s theory” (SegerstrŒle, 2002), or “The missing link in Darwin’s argument was provided by Mendelian genetics” (Ayala & Fitch, 1997). Darwinism was restored, not by taking away the power of genetics, but by redirecting it to support Darwinism. Clearly, genetics is the key to ruling the kingdom, like the One Ring that Rules them All in Tolkien’s world. The ones who have the ring have the power.

The story is made more fascinating by the fact that the key to power is literally a code of rules developed by a monk that remained lost for nearly half a century. The usurpers who discover The Monk’s Code misinterpret it, and use it to overthrow the true king, establishing a reign of error. But when The Founders decipher the true meaning of the Monk’s Code, The Architects campaign throughout the kingdom, spreading the news: the Monk’s Code proves that Darwin is the true king. Darwin’s rule is re-established, all opposition ceases, and the kingdom is unified.

Homework

If you would like to contribute a mutationism story, I would be happy to start a collection if you make it easy for me by providing a complete and well formed text item. Be sure to provide a quoted passage with a source, citing exact page numbers. If we get enough stories, lets try to recruit a sociologist or historian to study this further.

Summary

To summarize, the mutationism story is a myth that is retold in secondary sources. The basic story is simple: the discoverers of genetics misinterpreted their discovery, thinking it incompatible with Darwinism; Darwinism went into disfavor; population geneticists came along and showed that genetics was the missing key to Darwinism; Darwinism was restored and once again reigned supreme.

Next time on the The Curious Disconnect, we’ll start pulling on some of the loose threads of this story.

For now, note how the writers quoted above are genuinely baffled by our scientific history. It just doesn’t make sense to them. A century ago, most of an entire generation of scientists thought of genetics as a contradiction of Darwinism. This is a historical fact, and presumably it has an explanation that rational folks can understand by examining what scientists of the time wrote. But this historical fact mystifies Dawkins, Eldredge, Cronin, and others.

References

Anonymous. 2005. Ernst Mayr, evolutionary biologist, died on February 3rd, aged 100. The Economist, February.

Ayala, F. J., and W. M. Fitch. 1997. Genetics and the origin of species: an introduction. Proc Natl Acad Sci U S A 94:7691-7697.

Cronin, H. 1991. The Ant and the Peacock. Cambridge University Presss, Cambridge.Dawkins, R. 1987. The Blind Watchmaker. W.W. Norton and Company, New York.

Eldredge, N. 2001. The Triumph of Evolution and the Failure of Creationism. W H Freeman & Co.

Freeman, S., and J. C. Herron. 1998. Evolutionary Analysis. Prentice-Hall, Upper Saddle River, New Jersey.

Gould, S. J. 2002. The Structure of Evolutionary Theory. Harvard University Press, Cambridge, Massachusetts.

Ikemura, T. 1981. Correlation between the abundance of Escherichia coli transfer RNAs and the occurrence of the respective codons in its protein genes: a proposal for a synonymous codon choice that is optimal for the E. coli translational system. J Mol Biol 151:389-409.

Mayr, E. 1960. The Emergence of Evolutionary Novelties. Pp. 349-380 in S. Tax, and C. Callender, eds. Evolution After Darwin: The University of Chicago Centennial. University of Chicago Press, Chicago.

SegerstrŒle, U. 2002. Neo-Darwinism. Pp. 807-810 inM. Pagel, ed. Encyclopedia of Evolution. Oxford University Press, New York.

Stearns, S. C., and R. F. Hoekstra. 2005. Evolution: an introduction. Oxford University Press, New York.

Strickberger, M.W. 1990. Evolution (1st edition).

Notes

1 The defining characteristic of a myth is not that it isn’t literally true, but that it isn’t told for reason of being literally true, but for reason of being meaningful or poignant: a myth is a story with a cultural value, not necessarily a literal-truth value. The connection between myths and untruths, then, has to do with discoverability: when we find a pattern P = { X people are repeating story Y }, where X is a large number, this pattern by itself does not prove that Y is a myth because X people might have all discovered or verified Y independently; but if Y has diverse elements that are untrue (or unverifiable), then we can conclude that its repetition does not signify independent verification, suggesting that its a myth.

2The Oxford Encyclopedia of Evolution does not have an article on mutationism; the article on Morgan says nothing of his views on evolution; there is no article on Bateson; mutationism is only addressed peripherally in Hull’s article on the history of evolutionary theory; it is mainly addressed in SegerstrŒle’s article on neo-Darwinism.

Re-reading Provine (1971), part 1

Will Provine‘s seminal work of history, The Origins of Theoretical Population Genetics (1971), recounts how the foundations of modern neo-Darwinism were established in the first 2 decades of the 20th century.  Superficially, Provine’s book aligns with the standard triumphalist narrative in which the architects of the Modern Synthesis combine selection and genetics to yield a workable theory that refutes the mutation-driven view of early geneticists.

However, it also has another story to tell.  If we read the book with a critical eye, we’ll find a completely different story that explains why Provine himself, in a 2001 reprinting, said that the synthesis “came unraveled” for him in the period after 1980.

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The Mutationism Myth (6): Back to the Future

This post wraps up a 6-part series on the Mutationism Myth (a more scholarly version of this material ended being published in J. Hist. Biol. by Stoltzfus and Cable, 2014), and sets the stage for the future by locating the primary weakness of the 20th century neo-Darwinian consensus in its theory of variation. (more…)

Mutationism Myth (5): The Restoration

This is the 5th in a series of 2010 blogs entitled “The Mutationism Myth” (a more scholarly version of this material ended being published in J. Hist. Biol. by Stoltzfus and Cable, 2014)

The Mutationism Myth, part 5. The Restoration

In the Mutationism Myth (see part 1), the Modern Synthesis (MS) rescues evolutionary biology from the Mendelian heresy, by showing that genetics is consistent with selection. In reality, the Mendelians had already synthesized genetics and selection (part 3), but rejected Darwin’s errant views of heredity (part 2) and rejected, to varying degrees, the Darwinian doctrines that subordinated the role of variation so as to render selection the ruling principle in evolution. How, then, did the Modern Synthesis restore Darwinism?

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