Are we witnessing a new synthesis for evolutionary theory? If so, when did it begin? These are contested questions but one thing is known for sure: The phrase “Extended Evolutionary Synthesis (EES)” was coined by the philosopher/evolutionist Massimo Pigliucci in a 2007 article published in the journal Evolution, followed by a conference by the same name organized by Pigliucci and the theoretical biologist Gerd B. Muller in 2008. Now that a group of scientists headed by Kevin Laland has received a major grant from the John Templeton Foundation to study the EES, it’s a good time to touch base with the originator of the term.
DSW: Greetings, Massimo, and welcome to This View of Life.
MP: It’s a pleasure to be invited, David. We’ve known each other for a long time, and I think this is going to be fun.
DSW: Let’s begin with the story of how you coined the term, wrote the paper, and helped to organize the conference.
MP: The story goes a long way back, to when I was doing my PhD with Carl Schlichting at the University of Connecticut. While the direct focus of my dissertation was on some aspects of gene-environment interactions and phenotypic plasticity in the model plant Arabidopsis thaliana, Carl and I also shared a keen interest in the evolution of evolutionary theory, particularly during and after the articulation of the Modern Synthesis in the 1930s and ’40s.
That interest led us eventually to publish a book, Phenotypic Evolution: A Reaction Norm Perspective (Sinauer 1998), in which we first attempted to articulate something along the lines of what eventually became the Extended Synthesis. Mind you, a number of other books published before and around the same time made moves in similar directions, for instance Phenotypes: Their Epigenetics, Ecology and Evolution, by C. David Rollo. You can say that something was in the air, so to speak.
After graduating from UConn and doing a postdoc at Brown I landed a tenure track position at the University of Tennessee, and it was there that I gradually put together the approach that resulted in the Evolution paper, and eventually in the idea for the workshop that took place at the Konrad Lorenz Institute, then in Altenberg (Austria), from which the MIT book co-edited with Gerd came out. (You remember, you were one of the invited speakers!)
The Evolution paper was consciously written as a position paper to anchor future efforts, while the workshop was truly meant as an exploration of different people’s ideas, including some that were rather skeptical of the notion of an ES (e.g., Sergey Gavrilets and Greg Wray, among them). Indeed, Gerd and I put together the list of invitees so to achieve a range from reasonable skepticism (as opposed to, you know, knee-jerk reaction), to moderately positive (as we both saw ourselves), to radically pro (I would count Eva Jablonka and Stuart Newman in the latter group, for instance). I only regret we were not able to get more women in the group, but a couple of people we invited were not available that summer.
The workshop was a success, despite some bizarre coverage by a self-styled independent journalist who became convinced that there was a conspiracy afoot on the part of the “evolution industry,” a conviction she had reached because we had not invited outsiders to the workshop. (It was normal for that sort of small conference hosted at the Lorenz Institute to be closed to the public, in order to allow participants to speak freely and constructively disagree with each other.)
Interestingly, however, we picked up interest from both Nature and Science magazine, which ran full articles on the workshop, interviewing proponents and skeptics (If I recall correctly, Jerry Coyne was the only skeptic quoted in both pieces).
Both the general interest and especially the quality of the presentations and discussions convinced Gerd and me that this was well worth publishing as an independent volume, as opposed to just a special issue of the journal Biological Theory. MIT Press agreed, and we even managed to convince the publisher to obtain the elapsed rights for Julian Huxley’s original Evolution: The Modern Synthesis, to which we added a detailed new introduction in order to place it in the context of what we were trying to do with the Altenberg group. That was a fun project, worth on its own, since it allowed us to look at what Huxley had written back in 1942 with entirely new eyes.
DSW: Fascinating! I didn’t know about the new edition of Huxley’s book. Let’s talk philosophy for a little while. We have terms such as “Paradigm”, “Research Program”, and “Synthesis” that must mean something because we feel impelled to use them. Yet, at least for most people, they are maddeningly vague and often they are just bandied about for self-promotion. It is the job of philosophers to think clearly about concepts such as these. Do the major terms have separate meanings? Focusing on “Synthesis”, can it be defined clearly enough to unambiguously identify one? We need to get clear on what a synthesis is before we can decide if it is being extended!
MP: Indeed, and yes, philosophers can help here. Let me briefly address all three terms, which as you say are often banded around without this necessarily improving the clarity of one’s discourse. “Paradigm” is a technical term in the history and philosophy of science introduced by Thomas Kuhn back in the ’60s. The best explanation of what it means is that it comprises not just the dominant theory(es) in a given field, say the standard articulation of the Modern Synthesis in evolutionary biology, but also the chief methods used to conduct research in the field, the sort of questions that are deemed important, and even the textbooks that are used to train the next generation of scientists. So a paradigm is more than just a theory, it essentially captures a whole way of looking at things that characterizes a generation of scientists.
A “research program” is another technical term in philosophy of science, introduced by Imre Lakatos, who was a brilliant student of Karl Popper. Lakatos was trying to reconcile Popper’s prescriptive philosophy of science with Kuhn’s more descriptive-historical approach. He suggested that scientists work by deploying a theory — again, think of the Modern Synthesis — that is characterized by a core and a “protective belt.” The core is made of the elements of the theory that cannot be done without, on penalty of having to reject the theory itself. The protective belt is composed of auxiliary hypotheses that can be modified or even dropped without this affecting the core. For instance, in the case of the MS, one could argue that the concept of gradual — as opposed to saltational — evolution is a part of the core, but that the prevalence of allopatric (rather than sympatric) speciation belongs to the protective belt: should it turn out that evolution is really saltational, then the MS would be in some trouble; but if empirical data show that sympatric speciation is more common than the allopatric variety, well, so be it.
Now for the key concept of “synthesis.” This is not a philosophical term, as it was introduced by Huxley with the title of his famous book. What he meant to convey was the idea that the MS was not something radically different from Darwinism and neo-Darwinism (the late 19th century modification of the original theory that got rid of Lamarckian influences, largely thanks to the work of August Weissman and Alfred Wallace). Rather, it was a merging, a reconciliation, of Darwinism with the new discoveries coming out of genetics, and in particular the demonstration, achieved by Ronald Fisher, that Darwinism and Mendelism were not at all at odds with each other, as many thought at the time. The Synthesis then got expanded to a number of additional disciplines, from natural history to zoology and botany, and of course to paleontology (but, crucially, not to embryology and developmental biology).
It is in this same sense that most proponents of an Expanded Synthesis use the term: we don’t think that we are witnessing a Kuhnian paradigm shift, or the replacement of a Lakatosian research program by another one. We are, however, in need of explicitly and organically incorporating into the framework of the MS a number of new discoveries and concepts (phenotypic plasticity, epigenetic inheritance, evolvability, and so forth) that were unknown to, or unappreciated by, the architects of the Modern Synthesis.
DSW: That’s very helpful. I’m fascinated by the idea that the perception and processing of information must be limited to be effective. We can’t attend to everything so we must ignore some things (or at least place them in the background) so that we can attend to others. In this sense, the fact that the Modern Synthesis ignored development (for example) can perhaps be seen not as a failure but as something that was necessary to make progress on other fronts. Does this make sense, in general and for the modern synthesis?
MP: That’s an interesting way of looking at it, and I think there is some truth to it. But it was also a clash of personalities, among other things. We tend to forget that science is a human enterprise, and as such — at the least in the short run — affected by social dynamics and power struggles. One of the dominant personalities during the period in which the MS congealed was Ernst Mayr, who staunchly defended a number of notions that were important to him (such as allopatric speciation), and equally forcefully rejected others that didn’t fit his view of evolution (such as G.G. Simpson’s distinction between bradytelic and tachytelic evolution). It was Mayr who famously justified the exclusion of developmental biology from the Synthesis on the basis that, allegedly, developmental biologists were simply not interested in evolution. In fact, many were, but subscribed to views more similar to those of the famous geneticist Richard Goldschmidt, who proposed the idea of “hopeful monsters” to account for speciation and for major transitions in the fossil record. That idea didn’t sit well with Mayr’s emphasis on gradualism, and was accordingly purged from the canon, despite Goldschmidt’s stellar reputation at the time. Today we think that the notion of hopeful monsters was indeed misguided, but also that Goldschmidt was more prescient than Mayr in understanding the fruitful interaction between genetics and developmental biology — something that nowadays goes under the name of “evodevo.”
DSW: I remember Mayr’s dogmatic stance on allopatric speciation, which rivaled the dogmatism of others on group selection. Speaking of which—by my reading, the group selection controversy was not part of the Modern Synthesis and came later. Wright, Fisher, and Haldane each built simple models of group selection patterned after Darwin’s verbal discussion of the subject, and had separate opinions about the plausibility of group selection, but most of their attention was directed elsewhere, such as reconciling Darwinism with Mendelism. Wright’s shifting balance theory was mostly about the evolution of individual traits with a complex genetic basis, not the evolution of social traits. Mayr, Huxley, and Dobzhansky didn’t have much to say on the subject. It wasn’t until the publication of V.C. Wynne-Edward’s (1962) Animal Dispersion in Relation to Social Behavior and G.C. Williams’ (1966) critique in Adaptation and Natural Selection that issues surrounding group selection began to occupy center stage. More generally, major controversies in science might be less bundled together than we tend to think in hindsight. Is that also how you see it?
MP: Yes, which is why it would be a good idea if scientists paid attention not just to the philosophy of their own field, but its history as well. Most scientists train their graduate students in a highly “presentist” fashion, i.e., conceptualizing what happened in the past not only in a capsule, highly distorted form, but seen and evaluated from the point of view of the present.
This is a mistake, not just because it isn’t intellectually honest or accurate, but because it tends to obscure the roots and nature of scientific controversies, as well as to conflate things that should be kept separate.
As you say, the debates over group selection are a perfect example of this. If you ask current detractors of the idea, they think they are criticizing it from the point of view of the Modern Synthesis — even though the proponents of the MS didn’t address the issue at all, and indeed early population geneticists were more sympathetic to it than their contemporary academic descendants are comfortable in granting.
That said, group selection — in one form or another — will need to be incorporated in the Extended Synthesis. But that’s because the ES is not just a reaction to the MS, it is a new synthesis of the MS itself with a number of empirical and conceptual developments that have occurred in evolutionary biology since the 1950’s. Surely group selection, or more precisely, multi-level selection theory, qualifies!
DSW: In a related vein, announcing a synthesis is in part a way to make something happen in the future, not just a way of describing the past. Would the history of evolutionary biology been different if the Modern Synthesis had not been announced and given a name? The same question can be asked of any topic described as a new synthesis (e.g., Sociobiology) or with prefixes such as “Neo” (e.g., Neoclassical economics) and “Post” (e.g., Postmodernism). What work is being done with these terms? Are they just self-promotion or do they have a more legitimate function?
MP: Excellent point. Some of the critics like to dismiss what is being done under the umbrella of the ES as just self-promotion, which I think is both uncharitable and naive. Uncharitable because the many people that have been and will be working on expanding the evolutionary synthesis are serious researchers with interesting ideas to be tested, and only then to be validated or rejected. Naive because they seem to appeal to some sort of pure version of science, unadulterated by human emotions and foibles, which never existed and never will.
As I said above, the MS was in part the result of a clash of personalities. And so was the original Darwinism, with Darwin himself being very conscious of the fact that he needed to court allies and to keep in check foes. Science is a human activity, not something pursued from a Platonic realm by Platonic creatures.
So, yes, using terms like “synthesis,” “neo-,” “post-,” and the like is a programmatic statement. It can be conceived as the scientific equivalent of literary and political manifestos, a warning shot to the pertinent audience that there is a group of people with a new agenda in town. But this is the case just as well for the conservatives, so to speak, those who oppose the new direction. And ultimately, since this is science, new ideas will win out and become the new orthodoxy, if they have value. If not, they’ll join the huge heap of discarded notions, a heap, I hasten to add, without which science itself wouldn’t make progress.
DSW: What’s your opinion of the leadership role that Kevin Laland and his associates have taken, first with their recent articles and now with their major grant from the John Templeton Foundation?
MP: I wasn’t involved with the drafting of the Nature article, or of the original Templeton proposal. But I have now accepted their gracious invitation to join the effort, so I’m hardly in a position to provide neutral commentary on it. I have been wary (and to some extent, still am), of Templeton, because they have a clearly stated ideological and political agenda, with which I happen to disagree rather strongly. But at the same time, plenty of colleagues have assured me that whenever they have been involved with the Foundation there has not been any instance of interference on how the research was being conducted or the results presented. And let’s be frank, again, science is a human enterprise that needs funding. If one can’t get it from the National Science Foundation then one will go elsewhere for it. It has been done before, and it will happen again, plenty of times.
DSW: There is one final major topic that I would like to discuss with you. For me, a big part of the EES is the extension of evolutionary theory to include all human-related subjects. This part is notably lacking from Laland’s JTF grant. Don’t get me wrong—Kevin, many of his colleagues associated with the grant, and JTF are all not shy about studying evolution in relation to human affairs. Nevertheless, the fact that the EES can be so easily cleaved along human/nonhuman lines tells me that very different issues are involved in each case. Is it worth distinguishing two extended evolutionary syntheses?
MP: I’m not sure. On the one hand, I think that any sharp line dividing nonhuman from human is artificial and suspect. Human beings evolved, and continue to evolve, just like any other species on earth.
On the other hand, I’m also a bit skeptical of universal Darwinism, applied for instance to cultural evolution (as you do), or even to the cosmic variety (as physicist Lee Smolin does). There may be some value there, but humans are so quantitatively distinct from anything else on planet Earth, that for all effective purposes they show qualitatively novel behavior and phenomena that science has to account for. We do need a solid theory of cultural evolution, but we don’t have one yet, and I’m wary of attempts that simply extend biological Darwinism to culture, social relations, ethics, and the like. I think that at best they will end up being a part of the full picture, and it isn’t at all clear just how big that part will ultimately be.
I guess what I’m saying is that Kevin and colleagues are acting wisely, given the current state of our understanding to the subject matter.
DSW: Thanks for taking the time for this interview and more generally for your contributions to the field. Philosophy gave birth to the sciences and parental care is still required. Thanks for being a good parent.
MP: Well, don’t forget I’m also a son, when I put on the scientist’s hat. I guess that locates me in a really odd, borderline self-incestuous situation. I wonder if we could model that…