This is part of a continuing series of posts by Arlin Stoltzfus on the role of mutation as a dispositional factor in evolution. In this post, Arlin explains how defenders of the Modern Synthesis react in the face of serious challenges to the theory that was formulated in the 1940s and 50s. Rather than reject the theory, they engage in various forms of "synthesis apologetics."
Click on the links in the box (below) to see the other posts in the series.
by Arlin Stoltzfus
Rather than being a fixed scientific or philosophical position, Synthesis apologetics is an expression of the endemic conservatism that provoked Newman to remark on "an unremitting 90-year campaign to identify 'evolutionary theory' with 'Darwinism'."
The Darwin fetish remains strong, of course, but the stories used by conservatives to anchor the field in the past no longer focus on Darwin. Indeed, contemporary defenders of orthodoxy do not even defend genuine neo-Darwinism or the Modern Synthesis of 1959. They do not defend the creativity of selection, natura non facit saltum, recombination as the source of variation for selection, the irrelevance of mutation rates, the unity of the genotype, and so on. Most avoid the words "Modern Synthesis" and "neo-Darwinism."
Reactionary fringe meets mutation-biased adaptation
Introduction
1. The empirical case
2. Some objections addressed
3. The causes and consequences of biases in the introduction process
4. What makes this new?
5. Beyond the "Synthesis" debate
-Thinking about theories
-Modern Synthesis of 1959
-How history is distorted
-Taking neo-Darwinism
seriously
-Synthesis apologetics
6. What "limits" adaptation?
7. Going forwardSuperficially, it looks like they are defending the same Modern Synthesis defended by conservatives for decades, but instead of defending it as the substantive theoryC that permanently solved the problems of evolution by providing a Mendelian basis for neo-Darwinism, the "Synthesis" or "SET" is now defended as a research program, or an open-ended, content-free framework, essentially a body of theoryA.
This flexibility suggests that Synthesis apologetics is more an expression of scientific identity politics than of genuine conservatism (see Stoltzfus, 2017). Practitioners identify with what they perceive to be a long tradition of rightness, embodied in a favored list of ancestors, leading to the status quo. They celebrate and defend this tradition, and construct narratives to anchor new findings in it, undermining claims of novelty. If macromutations are found to be important, they seek out apparent references to macromutations from traditional sources (no matter how rare), thus reassuring each other that all good things come from tradition.
The slipperiness and goal-post-shifting introduced by Synthesis apologetics has undermined evolutionary discourse for decades. However, once we learn to recognize Synthesis apologetics as a cultural activity, it is easy to dismiss, allowing a clearer view of historic issues.
Legacy arguments
In a legacy argument, a traditional authority is associated with later work, on the grounds of instigating or inspiring that work. Examples include Charlesworth and Charlesworth (2009) associating Darwin with genetics, Soltis, et al. (2014) associating Stebbins with whole-genome-duplication, and Forterre (2012) associating Darwin with all evolutionary research.Legacy arguments reflect a Great Man view in which history is the biography of major figures. Their effect is to shift credit from scientists with lesser reputations to scientists with greater reputations, magnifying inequalities. Thus legacy arguments-- the lowest form of Synthesis apologetics-- are a form of intellectual piracy, e.g., to write a full-length article on the development of genetical views of evolution interspersed with obsequious praise of Darwin (i.e., to create an impression of relevance), without mentioning Lock, Morgan, Punnett, Davenport, Cuénot, Jennings, Castle, and others, is to rob from the poor and give to the rich.
The lowest form of the legacy argument, in turn, is Forterre's (2012) slavish metaphor in which we all work in "Darwin's goldmine," on the grounds that (1) Darwin invented the combination of variation and selection, and (2) we all work on that.
Legacy arguments are easy to dismiss once one realizes that the context for a legacy argument is always a scientific failure. The Darwin brand needs a legacy argument about genetics precisely because Darwin got genetics completely wrong, and likewise, Stebbins held that polyploids were evolutionary dead-ends.
The excluded middle
In the excluded middle or false dilemma fallacy, a position is advocated by rejecting an extreme alternative, ignoring other possibilities. This often occurs with gradualism. To argue for gradualism is easy if the only alternative is that new features typically arise fully formed in a single step, or that change is never gradual, or that the origin of higher taxa always reflects genetic revolutions. By contrast, it is hard to reject an alternative that combines gradual change with rare catastrophes and frequent modest-sized steps.
"I reflected much on the chance of favorable monstrosities (i.e., great and sudden variations) arising. I have, of course, no objection to this, indeed it would be a great aid, but I did not allude [in OOS] to the subject for, after much labor, I could find nothing which satisfied me of the probability of such occurrences. There seems to me in almost every case too much, too complex, and too beautiful adaptation, in every structure, to believe in its sudden production."Here natura non facit saltum, i.e., change built solely from "slight" or "infinitesimal" differences, is contrasted with "monstrosities" and "great and sudden variations." Why not "medium-sized and sudden"?
In a variant of the excluded-middle argument, the author associated with one extreme rejects the other extreme, then sneaks into the middle:
"From assisting Prof. Castle, I learned at firsthand the efficacy of mass selection in changing permanently a character subject merely to quantitative variability. Because of this and a distaste for miracles in science, I started with full acceptance of Darwin's contention that evolution depends mainly on quantitative variability rather than on favorable major mutations."Wright contrasts (1) merely quantitative (i.e., not discrete) variability with (2) miracles and major mutations. Then he mischaracterizes Darwin's position that nature does not make a jump (natura non facit saltum) as being that nature "mainly" does not make jumps. Wright has aligned himself culturally with Darwin and Castle, without distinguishing his position from the "some jumps" saltationism of Mivart, Huxley and Bateson.
Wright S. 1978. The Relation Of Livestock Breeding To Theories Of Evolution. Journal Of Animal Science 46:1192-1200.
The prevalence of such arguments in traditional sources invites the following form of apologetics:
No, no, the founding fathers opposed <alternative> because they rejected <extreme>, not because they rejected <middle ground>
Appropriation
Defenders of tradition frequently cite a historic statement related to some concept of emerging importance, in order to deploy the "we have long known" trope, claiming the concept on behalf of orthodoxy. Futuyma is the master of this technique, e.g., he cites Fisher to appropriate macromutations (here, p. 39) and Mayr for the EES developmental bias claim (here, 3.4). Other examples:- Darwin worked on earthworms, now a model system for niche construction, therefore niche construction is part of SET (Wray, et al. 2014)
- Lewontin advocates for reciprocal causation, therefore niche construction is part of SET (Svensson, 2018)
- Dobzhansky (1933) invoked Vavilov's theory of parallel variation, therefore the Yampolsky-Stoltzfus theory is part of SET (Dunning and Kruger, 2019)
Importantly, C' is often radically different from C, the target of appropriation, e.g., to appropriate the Yampolsky-Stoltzfus theory, Lynch (2007) writes "The notion that mutation pressure can be a driving force in evolution is not new," citing Darwin among others.
However, what about P? Why is a person involved in a chain of reasoning about theories? How does the Darwin-studied-earthworms-therefore-we-win argument depend on Darwin's activities? If Lamarck studied earthworms, would that count against neo-Darwinism? What if Goldschmidt founded a Society for the Study of Earthworms (SSE) in 1946? Would that make niche construction part of Goldschmidt's theory?
One does not reason about theories by studying the interactions of scientists with annelids. To know what a theory implies, we consult the inner logic of the theory.
Therefore, we have 2 ways to interpret this strange argument, P invokes C' therefore T includes C.
The first interpretation is that T is not a theory with fixed internal logic, but is something like a tradition, a socio-cultural construct whose meaning is negotiated biographically. This is clearly what Futuyma (2015, 2017) is doing, though he continues to mislead readers by using the word "theory."
The other way to interpret the argument is that the author is delegating his power of reasoning about T to P. Perhaps Svensson (2018), doubting his own ability to determine whether the Modern Synthesis implicates reciprocal causation, delegates this problem to Lewontin. However, Lewontin's "The organism as subject and object of evolution" [PDF] does not associate reciprocal causation with orthodoxy, but argues that "Darwin's variational theory is a theory of the organism as the object, not the subject, of evolutionary forces" (p. 87).
Indeed, just as the purpose of legacy arguments is to distract from scientific failures, arguments of the form P invokes C' therefore T includes C camouflage the inability to represent T as a genuine theory with an inner logic that implicates C.
Simplify to generalize
In his "goldmine" argument, Forterre dumbs down Darwin's theory to variation + selection. An analogous way to defend the Modern Synthesis is to leave out the internal logic, reducing it down to a content-free reference to basic concepts of mutation, selection, recombination, etc. For instance, we previously considered historic quotations from Huxley, Stebbins and Mayr appealing to the logic of opposing pressures and the gene pool theory. Here are the same quotations, without the logic:- "rate of hereditary change . . . evolutionary effect . . . adverse selection . . . mutation-rates . . . selection."
- "mutation . . . evolution . . . variability . . . selection . . . variability . . . selection"
- " . . . mutation . . . recombination . . . populations."
- "Evolution . . . Mutation . . . genetic variation . . . selection . . . evolutionary change"
This is a key tactic of Futuyma, who insists that the "core" of the Synthesis has not changed (other than by the addition of neutral evolution), while identifying the core post hoc as the parts that have not changed, leaving out discarded generalizations, neo-Darwinian doctrines, the gene-pool theory, etc. By contrast, the core of Mayr's (1981) Synthesis is a unanimous agreement on high-level generalizations: "the gradual mode of evolution, with natural selection as the basic mechanism and the only direction-giving force" (p. 23).
Conclusion
In 1969, molecular evolutionists pushed aside the Modern Synthesis of 1959 and embraced a new form of mutationism. Evolutionary biology has not had a master theory for 50 years:"There is no flexible Synthesis, but rather (1) a scientific discipline that changes its views appropriately, based on the latest findings, and (2) conformists spinning out increasingly flimsy versions of the claim that evolutionary biology is governed by a flexible master theory that traces back to Darwin through Mayr, et al." (Stoltzfus, 2017)Though we don't need a master theory, we still need historical narratives-- stories that make sense of change, identify sources, and assign credit.
Today the Synthesis story-- the Knights of the Synthesis, wielding a powerful theory, defeat all rivals and unite the kingdom, establishing the permanent reign of house Darwin-- is ridiculously unhelpful. The most fundamental experimental work since Johannsen is certainly not Dobzhansky's work on balanced inversions, but perhaps the Lenski experiment. Our thinking is more strongly shaped by the distinctive ideas of Gould and Dawkins, by the Spandrels paper, by arguments of Williams, Hamilton, Kimura and Maynard Smith, than by most of the scientists in the figure above. The practice of evolutionary research owes less to them than to Felsenstein and others who developed rigorous methods of inference and hypothesis-testing that have revolutionized the field, accelerating it much further down the path of hard science than the hand-waving style of Mayr, et al.
But this does not appear in the Synthesis story. None of these things appear in the Synthesis story.
Likewise, the molecular revolution had a huge impact on evolutionary thinking, partly through an influx from adjacent fields, e.g., Anfinsen, Dayhoff, Fitch, and Jukes were trained as biochemists or chemists. Today, on a daily basis, an enormous amount of practical inferential work is done by people and computers (e.g., in genome annotation and various forms of functional inference) using evolutionary modes of reasoning pioneered by Anfinsen, Dayhoff, Fitch and others, not based on anything they got from Mayr's Synthesis.
But the Synthesis story does not feature a molecular revolt in which the aging Knights of the Synthesis are challenged by outsiders wielding strange new weapons, who proceed to inhabit a previously unexplored territory that, over time, based on its hidden riches, develops explosively and comes to dominate trade with other kingdoms.
No comments:
Post a Comment