TVOL’s coverage of the Extended Evolutionary Synthesis (EES) continues with an interview with Kim Sterelny, one of the world’s most prominent philosophers of biology. Sterelny has served as editor of the journal Biology & Philosophy since 2000 and his books include Sex and Death: An Introduction to Philosophy of Biology, Thought in a Hostile World: The Evolution of Human Cognition, Dawkins vs. Gould: Survival of the Fittest, and The Evolved Apprentice: How Evolution Made Humans Unique. Sterelny was central in the development of the EES project funded by the John Templeton foundation, which recently launched its own website. He was a participant in the Nature exchange “Does evolutionary biology need a rethink?”1 (answering “yes”) as well as a coauthor of the major 2015 review article on the EES published in Proceedings of the Royal Society of London B.2

David Sloan Wilson: Welcome Kim. I recall many fine conversations with you. Let me begin by asking you to explain in general terms how philosophers contribute to the study of evolutionary biology. What do you bring to the table?

Kim Sterelny: A couple of things. For one, a lot of foundational questions in evolutionary biology are curious hybrids of conceptual, formal and empirical issues. Think for example of the history of gene selectionism or multi-level selection. It took a lot of hammering and tinkering to get clear which claims about selection were genuinely empirically and causally distinct; which were empirically equivalent but perhaps heuristically distinct, and which really were just verbal disputes. It is also true that philosophers bring both the time and the skills to do integrative and synthetic work across different research traditions. Biologists are with few exceptions almost forced to specialise quite narrowly; they have to produce data; philosophers only have to think about it.

DSW: You chose an excellent example with gene selectionism and multilevel selection, where the contributions of philosophers has been huge. Turning now to the EES, what interests you about this topic, and what are the key issues raised by the EES that philosophers can help biologists to address?

KS: I began in philosophy of biology with Richard Dawkins and The Extended Phenotype. Dawkins is a challenging figure here; in some ways ultra-orthodox; in others, quite subversive; The Extended Phenotype is a quite subversive book, and was great road into philosophy of biology. I then fell in with Russell Gray, who alerted me to the empirical and conceptual seriousness of non-genetic selection, and with Maynard Smith, who got me thinking about major transitions, and I took up thinking about human evolution as a case study of major transitions. That never happened; the example ate the project. But it hooked me into the centrality of niche construction, feedback processes in evolution, non-genetic inheritance and multi-level selection. I think the primary focus there is the interaction between niche construction and non-genetic inheritance: how the fidelity and bandwidth of cultural inheritance depends on niche construction.

DSW: I am entranced by the same set of issues. Whatever we decide to call it, it’s incredibly interesting and important for understanding and improving the human condition. You mention Dawkins as an influence, or, at least, a draw. You wrote a whole book on “Dawkins vs Gould”, which analysed their intellectual differences. Are there parallels to the debates at the heart of the extended evolutionary synthesis? Can we, for instance, see something of Gould’s stance in the EES, and something of Dawkins amongst the critics?

KS: In some ways, it is easy to think of Dawkins as a critic. Adaptation is central to his conception of evolution, and he has always been skeptical of multi-level selection. But his work on the extended phenotype overlaps with niche construction ideas, and he was an early advocate of applying evolutionary models to culture, though the specific form of the idea, memetics, has never really progressed beyond metaphor. Even so, he did formulate the conceptual foundations of inheritance in ways that do not tie it to the specific mechanisms of the gene. Gould’s Ontogeny and Phylogeny was an important early essay in evo-devo, and that fits into his position as an EES ancestor. And of course he did have a multi-level conception of evolution. But species selection has never really gone anywhere and his big final book made surprisingly little connection with the formal development of evolutionary theory. Perhaps his most important message was the importance of integrating palaeobiology within evolutionary biology, and everyone in the debate needs to take that message in.

DSW: What about developmental bias and constraint? That was certainly central to Gould’s stance, and it would equally appear to be central to the EES?

KS: Indeed. Though Gould wrote about historical and structural constraints as well. He tended to infer developmental constraint from what he took to be the surprising stability of the supposed Bauplans of major metazoan clades, but it is very hard to know just how good that inference was: there was no real null model to compare actual history against the history we should expect, if evolutionary possibility was not heavily constrained. I always found Gould’s work interesting and often plausible, but it was often very hard to see exactly how one might test his ideas against the world; think, for example, of his ideas about replaying the tape of life in Wonderful Life.

DSW: There seems to be some confusion as to what the EES is. Is it a new research program? An attempt to bring about paradigm-shift? Just another way of thinking? What do you think the EES ought to be? What useful role can it play within evolutionary biology?

KS: I think it is more general than a specific research project; less grandiose and pretentious than a paradigm-shift; somewhat more specific than just a new way of thinking. I think of it as a research framework: a somewhat richer conception both of the mechanisms involved in evolutionary change; of the questions which can be productively asked; and of how evolutionary change should be represented and modelled.

DSW: Can we unpack that a little bit? What do you mean by a research framework? I notice that in your papers the “EES” is contrasted with the “MS”, or modern synthesis, which is described as a “conceptual framework”. Can you clarify what you mean by these terms? What job does the MS do, and in what ways do you envisage the EES providing an alternative?

KS: Think for example of the Modern Synthesis, and its conception of the role of the relationship between variation and selection. No defender of the Modern Synthesis denied that variation was essential to evolution, but they thought that in most taxa, over the medium to long run, variation was generated fairly evenly, and in small increments, around existing phenotypes, and especially those phenotypes that occurred at high frequencies in the population. Of course that was an idealisation, and known to be an idealisation, but it focussed attention on selection, population structure and drift as factors that varied from case to case: these were the difference-making factors. Evolutionary developmental biology (or at least some evolutionary developmental biologists) suggests biases in the supply of variation can and does shape evolutionary trajectories over the medium and long-run. I am particularly interested in niche construction and its importance. Again, no defender of the synthesis would have actually denied that organisms can impact on their own environment, but they assumed that in most cases (the exceptions were mostly organisms’ social environments), those impacts were not sustained, systematic, cumulative, resulting in evolutionary feedback loops between lineage and environment. The EES takes such feedback loops to be not just important, but tractable. Every framework backgrounds some phenomena, and some questions, and foregrounds others, identifying them as productive foci for research. In saying this, it is important to acknowledge that the MS was not monolith, and has been an umbrella for really important work on coevolution, so niche construction builds on existing foundations. The same is true of multi-level selection and extended inheritance. That is one reason why I resist talk of revolution and paradigm shift; it is important to recognise and celebrate the immense continuity between the EES and previously received wisdom in evolutionary biology.

DSW: I’m entirely in agreement with your assessment. I guess we all hope that the EES will prove to be a productive way of thinking, but ostensibly it opens up a Pandora’s box of complications. For instance, how do researchers define evolution, or measure fitness, if there are multiple inheritance streams? The clean separation of development and inheritance, or of proximate and ultimate causes, all suddenly starts to look muddied. That is perhaps food and drink for philosophers, but should we worry that it might create practical problems for evolutionary biologists?

KS: I think that is always a legitimate worry. Whenever one goes from a relatively simple framework to a more complex one, there is a worry about tractability: mathematical, computation, experimental. There are though reasons for cautious optimism: there is existing work in multi-level selection theory, niche construction and evolutionary developmental biology that incorporates some of the phenomena that the EES wants to move closer to centre stage of evolutionary thinking. Moreover, Levins’ famous 1966 paper on models in population ecology suggested an important strategy in response to complexity: develop a family of models, that simplify the target system in some respects, but capture its real complexity in another another, and treat as real those results that are robust across those models. It is always possible that the world is more complex than we are smart. But there is no reason to be pessimistic in advance about that possibility.

DSW: It seems to be quite common for scientific inquiry to begin with simple models and then add complexity as needed—even though the topic was known to be complex all along.

One final question: By all accounts, the exchange in Nature generated an extraordinary reaction, exciting huge interest, extreme polarisation of opinion, and often very strong emotions. I believe there was a similar response to a recent Royal Society discussion meeting. Can philosophers help scientists to understand these reactions? Is it a naïve idealization to characterize the scientific process as about objective shifting of data? Are we witnessing clashes between alternative ways of thinking? Or are these struggles for power, influence and money?

KS: I think there is some bad history here that may be part of the problem. In much of the early talk about the need for a new or extended synthesis, defenders of that idea massively over-emphasised the discontinuity between the modern synthesis and its supposed successors. Remember Gould’s talk about the modern synthesis being dead; the need for a paradigm shift, and so on. That kind of heated, over-claiming rhetoric got me off-side, and I was not even a defender of the synthesis. I suspect pretty deep suspicions got laid down then. On top of that, there is of course all the usual human baggage; practicing scientists do have personal and professional stakes in their own research history. In philosophy, it is completely fine to write papers and books denouncing your former self; it would do me no career damage at all to say my previous views about the nature of evolution were completely wrong; this is what I think now, and go on to argue for some new heterodoxy. Being wrong; being shown wrong is quite normal in philosophy. That is not true in science in general or in biology. So there is bound to be a certain degree of professional defensiveness. What makes science so unique as a human institution is that, especially over the medium run, it is so remarkably sensitive to the objective shifting of data. That probably depends on the distributed nature of research communities; on the existence of a decent number of research groups, with some information flow between them, but still working quasi-autonomously. So “big science” is potentially a serious problem to the capacity of research communities to respond to the objective informational environment. So far though I do not see any signs that the evolutionary biology research community has become dominated by just one or a few players.

DSW: Ah, there is much to discuss there! In the case of the group selection controversy, the “medium run” has been well over half a century! It was philosophers such as Elliott Sober and yourself who identified some of the barriers to progress, such as confusing frameworks that provide different perspectives on the same causal processes (equivalence) with frameworks that invoke different causal processes. Philosophy gave birth to the sciences and still needs to provide parental care. Thanks for this interview and I look forward to our next opportunity to discuss life, the universe, and everything.

1. Laland, K., Uller, T., Feldman, M., Sterelny, K., Müller, G. B., Moczek, A., … Strassmann, J. E. (2014). Does evolutionary theory need a rethink? Nature, 514(7521), 161–164. http://doi.org/10.1038/514161a

2. Laland, K. N., Uller, T., Feldman, M. W., Sterelny, K., Mu, G. B., Uller, T., & Moczek, A. (2015). The extended evolutionary synthesis : its structure , assumptions and predictions. Proc. R. Soc. Lond. B., 282. http://doi.org/http://dx.doi.org/10.1098/rspb.2015.1019