There has been a lot that has been said about the recent Guardian Article on the group of evolutionary biologists who claim that the Modern Synthesis needs an update and should be replaced by the so called Extended Evolutionary Synthesis (EES).
Just to make this clear, the Modern Synthesis is a theory resulting from the merger of Darwin’s evolution by natural selection with Mendel’s laws of inheritance. This view was codified by population geneticists in the 1950s and has a particular view of how evolution operates.
But is this view still useful? Is it complete? Does it need a reform?
Proponents of the EES believe so. In fact, they would say that their new view equates to a “paradigm shift”. Interestingly, the reaction of most evolutionary biologists is not a rejection of these new ideas, but rather “meh”. Hardly the response you would expect from some direct attack on the core guiding principle of the biological sciences.
Despite this, there has been real battles — the 1950s view of evolution held by those who codified the Modern Synthesis has faced some real challenges. This was due to the molecular evolution revolution, which gave the first glimpses of the molecular basis of inheritance and the first look at how biological information changed at the molecular level in the real world. For more on this history, read our article, Non-Darwinian Molecular Biology, or watch this excellent Youtube video (Evolution Isn't Always For The Best) by Jake Brown. But this fight has little to do with the EES. The real challenge to the Modern Synthesis came with the rise of Neutral Theory, and with the resulting conflict, what is often referred to as the Selectionist-Neutralist controversy. This indeed sparked bitter attacks and counter attacks. Although lately the war has died down a bit, it is still smouldering.
It should also be noted (as Jerry Coyne points out) that the existence of neutral phenotypes was considered by Darwin to be possible and likely. (Incidentally you can always tell who has read the Origin of Species - one tell is to point out that Darwin was not a strict “Darwinian”, the other that he never once writes about finches.) But Coyne’s argument misses the point. The idea that neutral phenotypes and neutral evolution were “important” for the evolution of most species was an anathema for many of the defenders of the Modern Synthesis including Ernst Mayr and Ronald Fisher.
To be fair, some in the EES camp point to a lack of incorporation of the Neutral Theory into evolutionary thinking as one of the problems with the Modern Synthesis, but then lump it in together with other concepts that are … “meh”. Yes, evolution theory needs to take in a pluralistic view of the causes of phenotypic change and/or conservation beyond simple adaptionalist story telling (just read the Spandrels of San Marco to get a taste of this critique - including neutralism, spandrels, pleiotropy, developmental constraints and historical contingencies), but I’m not sure that transgenerational epigentic inheritance is so widespread (it happens, but is pretty rare and likely not subject to evolutionary change beyond its genetic programming), or that niche construction is so profound as to cause a transformation in how we all think. Some ideas, like plasticity, are interesting, but hardly controversial. Then there are ideas like Lamarckism — beyond the CRISPR system in bacteria, I do not know of any other REAL examples. Other ideas are just silly (the concept of the gene is dead … please) or simply ignorant (the alleged central dogma has been “demolished“ … have you even read Crick’s Nature paper from 1970? or his original formulation in 1958? Nope.)
I don’t want to say that all of the ideas that the EES advocates are ho hum or misinformed. Multilevel selection theory can provide quite a bit of insight on long-term evolutionary trends and explains many evolutionary outcomes that are very counterintuitive. Another idea that is sometimes advocated by EES folk is mutationalism. The role of mutation in guiding evolution is quite interesting and insightful. As Arlin Stoltzfus points out, the contribution of mutation to evolution was widely underappreciated by the founders of the Modern Sythesis. Some of this had to do with the dismissal of proponents of the “hopeful monsters” hypothesis, but a lot of this had to do with simply bad assumptions made by the architects of the Modern Sythesis - that trends in mutational bias were unimportant to the ultimate outcome of evolution and the evolutionary innovation were “created” largely by recombination. It would seem that some in the EES camp also want to raise the issue of mutations in evolution, but most of the insightful work is being done by others outside the EES camp (like Stoltzfus, and Nei before him). Others, such as Jerry Coyne, have pointed out that many ideas from mutation-driven evolution have been accepted by mainstream evolutionary theorists. This may be so, but I’m not sure that they have really absorbed those concepts. In any case, the major implications are readily seen at the molecular level, and most of the EES folk appear to be agnostic of most developments in molecular evolution. Not to say that what happens at the molecular level are unimportant - in fact, the reverse is true, but no matter, molecular evolution does not seem to be a primary concern of the EES folk - and when they do write about it, they mess it up.
Then there is the whole idea of the culture war aspect that was discussed between Jerry Coyne and Steven Pinker. Maybe???? Some EES ideas have this hoaky leftist utopia feel to them (like Lamarckism and transgenerational epigentics). But unlike what Pinker states, the vast majority of evolutionary theoreticians are hyper-adaptaionalists, so his critique rings a bit hollow. If anything, many in the EES camp itself have these hyper-adaptaionalist tendencies, and have not really integrated Neutral Theory and evolution by random genetic drift into their world view. I see no EES writing about nearly neutral mutations. So are they really revolutionaries? Or simply adding a few footnotes to the old Standard Model while being blissfully unaware that they really haven’t absorbed aspects of the real revolution (i.e. Neutral Theory)? I think that the later is closer to the truth.
Links:
Do we need a new theory of evolution? (the Guardian)
Once again: A misguided article on why the theory of evolution is obsolete (Jerry Coyne)
Pinker: The “evolution war” is also a culture war (Jerry Coyne)
Darwin’s modernity in “The Origin”: anticipating the neutral theory and punctuated equilibrium (Jerry Coyne)
For more on why we don't want another "Synthesis" (Arlin Stoltzfus, Twitter)
New Scientist doesn't understand modern evolutionary theory (Larry Moran on the EES)
Proponents of the Extended Evolutionary Synthesis (EES) explain their logic using the Central Dogma as an example (More from Larry)