Evolutionary biology, we are told, does not need a master theory. Researchers should think in terms of “contemporary mainstream thinking.” From Arlin Stoltzfus at Biology Direct:
Why we don’t want another “Synthesis”
Abstract:High-level debates in evolutionary biology often treat the Modern Synthesis as a framework of population genetics, or as an intellectual lineage with a changing distribution of beliefs. Unfortunately, these flexible notions, used to negotiate decades of innovations, are now thoroughly detached from their historical roots in the original Modern Synthesis (OMS), a falsifiable scientific theory. The OMS held that evolution can be adequately understood as a process of smooth adaptive change by shifting the frequencies of small-effect alleles at many loci simultaneously, without the direct involvement of new mutations. This shifting gene frequencies theory was designed to support a Darwinian view in which the course of evolution is governed by selection, and to exclude a mutation-driven view in which the timing and character of evolutionary change may reflect the timing and character of events of mutation. The OMS is not the foundation of current thinking, but a special case of a broader conception that includes (among other things) a mutation-driven view introduced by biochemists in the 1960s, and now widely invoked. This innovation is evident in mathematical models relating the rate of evolution directly to the rate of mutation, which emerged in 1969, and now represent a major branch of theory with many applications. In evo-devo, mutationist thinking is reflected by a concern for the “arrival of the fittest”. Though evolutionary biology is not governed by any master theory, and incorporates views excluded from the 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. (public access) More.
From the article:
The Synthesis narrative, maintained only by enormous sacrifices of rigor and clarity, must be abandoned. The OMS is a clever theory when considered as a special case, but proposing it as a master theory was premature, and claiming that it was established empirically was an exaggeration bordering on delusion. The fact that the OMS failed by the 1970s tells us two things: the historical narrative of the Grand Unifying Theory is false, and more importantly, evolutionary biology does not need a master theory.
The correct term to describe contemporary mainstream thinking in evolutionary biology is “contemporary mainstream thinking”. To call it an “Evolutionary Synthesis” or “Modern Synthesis” shows a disregard for scholarly rigor. 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.
Indeed, abandoning the notion of a unified master theory is an obvious reform for 21st-century evolutionary biology. When the implicit demand for such a theory is removed from the current EES debate, for instance, what is left is a set of causal factors relevant to niche construction, developmental bias, and phenotypic plasticity, each of which deserves to be evaluated on its merits. Debates over such factors would be more productive if proponents of novel causes were to follow the model of Kimura’s Neutral Theory, which does not merely invoke a possible mode of change, but makes a precise general claim about the size of its effects in evolution.
This kind of conceptual reform is possible without revolution. Evolutionary biology was changed permanently by the critique of “good for the species” arguments by Williams , and by the take-down of naive adaptationism by Gould and Lewontin . These reformers subverted conventional habits of thought by exposing their shallowness. Today, wishy-washy defenses of an ongoing “Synthesis” are easy targets for a badly needed reform in our ongoing discourse on the state of evolutionary thought: rejecting Synthesis propaganda, and accepting evolutionary biology as a legitimate scientific discipline that entertains bold conjectures about the measurable effects of novel causes, with no need for a master theory. The era of master theories based on ruling principles and grand schemes is long past. The OMS was the last such theory. There will not be another.
It sounds as though evolution is becoming a history of life, as opposed to a metaphysic for life, which is more or less what a lot of us have thought should happen for quite some time. The less we hear of Thus spake Darwin and Thus saith Ernst Mayr the better.
The article was reviewed by W. Ford Doolittle, Eugene Koonin and J. Peter Gogarten. In particular, Doolittle offers in a reviewer’s report:
Stoltzfus boldly wades into the muddy waters of the Modern Synthesis and recently proposed “extended” versions thereof, and concludes that we don’t need any such grand theorizing. There are many points he makes that I like, and since this is a topic he knows better than I, I cannot fault his history other than in a general way. Each of us has come to believe what we do about evolution through idiosyncratic combinations of reading, listening and thinking, and I doubt that there is any one true story about this. Certainly evolutionary biologists suffer from the fact that our major or most widely read history writers have generally been practitioners with their own axes to grind. We would not expect politicians to write unbiased political histories, but we biologists seem to trust our own kind, as if scientists can more easily transcend themselves. My generation of molecular biologists (or at least I) took far too long to realize that Ernst Mayr was not in fact a disinterested observer. Stoltzfus points this out, and shows how the OMS (the original modern synthesis) assumed that relevant populations already harbor sufficient relevant genetic variability to adapt to most environmental challenges.
Incidentally, Ford Doolittle has justified mental gymnastics in the past (2009) because “much is at stake socio-politically,” namely the need to defeat “anti-evolutionists” in “the culture wars.”
He must have decided not to let the anti-evolutionists be the only adults in the room. Good thought that.
See also: What the fossils told us in their own words