I’ve commented more than once on how the accusation “You don’t understand evolution” gets slapped on practically everybody, from Fundamentalists to senior evolutionary biologists. If you already know your ignorance you’ll be used to hearing it should you ask the wrong questions at places like BioLogos (I’ve had it thrown at me there twice this week already, though I’ve studied it a bit over the last 50 years or so). Even if you’re highly trained, though, you are not immune (as my piece linked above demonstrates). In both cases, the ultimate reason is probably the same.
And that is that evolution is almost never discussed, on the large scale, in terms simply of a range of scientific ideas to be evaluated in relation to each other, but in terms of a deeply-entrenched mythical structure. A new and, I think, important article by Arlin Stoltzfus is, to my mind, essential reading to gain a clearer view of how that mythology obfuscates everything. If you know enough about evolutionary theory to be confused, the article will clarify much. You may even end up thinking your understanding isn’t as deficient as you assumed!
The last time I simply linked to a paper with little comment it led to good discussion, so I’ll try the same again, putting below just a few provocative quotes to get you to read the whole thing (without which reading, any comments will not be of significant value!).
- Though evolutionary biology is not governed by any master theory, and incorporates views excluded from the Original Modern Synthesis (hereafter “OMS”), the recognition of these changes has been hindered by woolly conceptions of theories, and by historical accounts, common in the evolutionary literature, that misrepresent the disputes that defined the OMS.
- The OMS failed rather quickly as a master theory when, in the early 1960s, the results of comparative sequencing prompted biochemists to invoke precisely the kind of mutation-driven view that Fisher and the architects of the OMS had sought to exclude. In the OMS view, visible change is a smooth selection-driven shift in quantitative characters, and the underlying genetic change consists of simultaneous shifts in the frequencies of alleles at many variable loci. Comparisons of protein sequences revealed a long-term process that simply does not look like this.
- [T]he development and use of mathematical models reveals unambiguously that the OMS does not suffice to depict evolutionary dynamics, because it fails to cover mutation-driven dynamics. This failure is not a mistake or oversight, but an intentional feature of the OMS reflected in the explicit claims of Mayr, Dobzhansky, Simpson, Stebbins and others that selection uses abundant variation in the “gene pool” and does not wait for new mutations.
- The dynamics that give the “gene pool” its mojo are largely inapplicable in prokaryotes, the organisms that have dominated the biosphere for most of its existence. The OMS is not the theory used by molecular or microbial evolutionists, though it may be a perfectly good theory for special cases, e.g., for short-term changes in quantitative traits in large panmictic diploid sexual populations [my italics – read “microevolution”!].
- Amnesia and distortion are perhaps inevitable given that scientists are regularly exposed to a Synthesis narrative, common in the evolutionary literature, in which a single Grand Unified Theory sweeps away foolish rivals, unites the field, and establishes a permanent orthodoxy. Without the constraints provided by crucial historical facts, conceptions of this grand theory have drifted, while the Synthesis story remains. What scientists need to understand is that this narrative was introduced, not by independent historical scholarship, but by the architects of the OMS themselves. Some historians call it “Synthesis Historiography”, i.e., telling history in ways that turn out right for the Modern Synthesis.
- In short, the accounts of history in the evolutionary literature are not good sources for reliable information about developments in evolutionary thinking. In practice, they have fostered a kind of conceptual immune system: scientists guided by these stories have difficulty appreciating genuine alternatives, which are only known through caricatures, so that all reasonable ideas are assumed to align with the Synthesis.
- Most importantly, to propose that evolution can be, or must be, understood via population genetics is a curiously empty “theory” relative to historic attempts to specify the nature and importance of the high-level causes of evolution, e.g., the origin of novelty, internal vs. external sources of direction, etc. This “theory” does not appear to be a falsifiable conjecture, but is more like a methodological claim about the most productive way to think about evolutionary problems. To invoke this as though it were a master theory is to confess that there is no such thing.