EMANUELE SERRELLI1 1 The Extended Evolutionary Synthesis: a 2 metascientific view of evolutionary 3 biology, and some directions to transcend 4 its limits 5 6 Abstract 7 To approach the issue of the recent proposal of an Extended Evolutionary Synthesis (EES) put forth 8 by Massimo Pigliucci and Gerd Müller, I suggest to consider the EES as a metascientific view: a 9 description of what's new in how evolutionary biology is carried out, not only a description of 10 recently learned aspects of evolution. Knowing 'what is it to do research' in evolutionary biology, 11 today versus yesterday, can aid training, research and career choices, establishment of relationships 12 and collaborations, decision of funding and research policies, in order to make the field advance for 13 the better. After reviewing the concepts associated to the EES proposal (categorized for convenience 14 as mechanisms, measures, fields, perspectives and applications), I show their transience, and sketch 15 out ongoing disagreements about the EES. Then I examine the deep difficulties, i.e., the enormity and 16 complexity of the covered field, affecting the achievement of trusted metascientific views; the 17 insufficiency of conceptual analysis to capture the substance of scientific research; the entanglement 18 between empirical and metascientific concepts, between multiple chronologies, and between 19 descriptive and normative intentions; and the ineliminable stakeholding of any reviewer involved in 20 1 "Riccardo Massa" Department of Human Sciences, University of Milano Bicocca Corresponding author: Emanuele Serrelli, "Riccardo Massa" Department of Human Sciences, University of Milano Bicocca, Piazza dell'Ateneo Nuovo 1, 20126 Milano, Italy. Email: emanuele.serrelli@unimib.it © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 2 the reviewed field. I propose that disciplines such as scientometrics, ethnography, sociology, 21 economics and history, combined with conceptual analysis, inspire a more rigorous approach to the 22 evolutionary biology scientific community, more grounded and shared, confirming or transforming 23 claims for 'synthesis' while preserving their maintenance goals. 24 Keywords 25 Biology; Evolution; Theory; Evolutionary Synthesis; Scientific Community; Modern; Extended 26 Introduction 27 More than once, through its history, evolutionary biology has tried to get a meaningful snapshot of 28 itself. A few of these crucial moments are defined 'syntheses'. These include the Modern Synthesis 29 some decades ago, and the Extended Evolutionary Synthesis today. In this paper I assume that a 30 comprehensive and reliable picture of evolutionary biology is, in principle, very useful to evolutionary 31 biology itself as a research enterprise. Fragmentation coming, for example, from 32 compartmentalization and hyper--‐specialization, is often seen as hindering the advacement of the 33 science of evolution in many ways (Sidlauskas et al. 2010). The lack of a general picture of evolution, 34 or at least of a sense of communal endeavour, can prevent a researcher from grasping the potential 35 evolutionary relevance of her study case, or from accessing precious resources. A sense of 36 evolutionary biology as a moving whole can be crucial for many important issues such as biology 37 training, or funding and rewarding policies. In this light, syntheses deserve careful consideration 38 because of their potential 'maintenance effects', i.e., effects that ultimately aid evolutionary biology 39 in pursuing its knowledge aims. This paper analyzes the Extended Evolutionary Synthesis and, 40 indirectly, the Modern Synthesis. Both 'syntheses' are metascientific views, in that they consist in 41 claims about 'what it is to do research' in evolutionary biology at different times. Only indirectly they 42 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 3 are scientific claims about evolutionary processes. As we shall see, metascientific views are 43 intrinsically complex: they should require a great effort for domesticating a huge mass of scientific 44 literature (the latter being, in turn, only one aspect of scientific work); they intertwine metascientific 45 with scientific claims, descriptive with prescriptive aspects, and multiple historical chronologies; and 46 they are often elaborated through conceptual analysis by one or few scientists who cannot but rely 47 on their particular experience and hold stakes in the scientific debate. 48 In 1980 Ernst Mayr and William Provine (Mayr and Provine 1980) edited a reconstruction of the 49 Modern Synthesis that was to become its official, although in fact multifarious, account. The account 50 was paralleled and immediately followed by pleas for an extension of the Modern Synthesis. Some 51 critics, like early Stephen Jay Gould (1980, 1982), were more radical, whereas others, like G. Ledyard 52 Stebbins, adopted a more integrative approach (Stebbins and Ayala 1981; Stebbins 1983).2 Calls for 53 an extension of evolutionary theory and evolutionary biology were repeated over the years, invoking 54 a transition from the Modern Synthesis (MS) to the Extended Evolutionary Synthesis (EES). 55 Here I focus on a recent initiative promoted by Massimo Pigliucci and Gerd Müller.3 Pigliucci (2007) 56 defined the MS as "the current paradigm in evolutionary biology [...] whose conceptual framework 57 goes back to the 1940s" (p. 2743). For Müller (2007) the MS is "the prevailing theoretical framework 58 of evolution that resulted from a combination of genetics, systematics, comparative morphology and 59 palaeontology in the 1930s and 1940s" (p. 946). Both Müller and Pigliucci wanted to point out some 60 missing elements of the MS that are being added by current evolutionary research. Initially, they 61 both focused on 'organic form' as something overlooked by the 'essentially' genetic MS, then they 62 2 Stebbins is also considered among the architects of the MS (Pigliucci 2009, p. 220; Pigliucci and Müller 2010, p. 8; Stebbins 1950). Both Gould and Stebbins, although in different ways, moved towards macro--‐evolutionary extension of the MS (Serrelli and Gontier forthcoming). Pigliucci and Stebbins share, besides their interest in extending the MS, their specialization: both are botanists. 3 It would be necessary to assess Pigliucci and Müller's discontinuities and continuities with respect to previous works like Gould's or Stebbins's. This would be particularly important because the EES has the ambition of summoning the pleas that have been accumulating over the years. The analysis is however beyond the scope of the present review, but some disconnects will be mentioned. © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 4 consciously started a proliferation of reflections on the EES,4 where, as we shall see, they assembled 63 a broader extension beyond the issue of 'form'. 64 The idea of an EES enjoyed some success. For example, several scientific journals reviewed the EES 65 book (Pigliucci and Müller 2010) as a research proposal (Plutynski 2011; Reiss 2011; Travis 2011; 66 Witteveen 2011; Handschuh and Mitteroecker 2012). Some scientists accepted the challenge of 67 imagining how the EES will eventually be (Brooks and Agosta 2012), possibly pointing out neglected 68 extensions (Boto 2010; Weber 2011). Some scholars used the EES perspective to look at evo--‐devo 69 (Love 2009; Medina 2010), at population genetics (Akey and Shriver 2011), and at other fields (Noble 70 2011; Danchin 2013; L.A.B. Wilson 2013), and many focused on epigenetics (Danchin et al. 2011; 71 Schrey et al. 2012, Dickins and Rahman 2012). The socio--‐cultural sciences showed an interest in the 72 extension of the MS as well (Mesoudi et al. 2013; Laland et al. 2009).5 73 The EES was described by Pigliucci and Müller as an addition of key concepts to evolutionary theory. 74 After looking at their ideas in some detail, I am going to highlight the dynamism of concepts occuring 75 in their view over a few years. The complexity of the EES as a metascientific view, and the challenges 76 presented by its achievement, are addressed in the subsequent sections. The conclusion of the 77 present paper is the following: if metascientific views are as important to scientific research as they 78 seem, then, although their complexity cannot be eliminated, they should be specified and grounded 79 by means of more adequate methodologies than the ones employed to date. 80 1. Back to a theory of form? 81 4 See, for example, Pigliucci (2008a,b,c, 2009), Pigliucci and Müller (2010), Müller and Pigliucci (2010), Craig (2010, 2011), Love (2012), Callebaut (2013), Mesoudi et al. (2013). 5 An example in Europe was the project called "Implementing the Extended Synthesis in Evolutionary Biology into the Sociocultural Domain", carried out in 2012--‐2013 by the Lisbon Applied Evolutionary Epistemology Lab (Serrelli and Gontier forthcoming). Detailed information on the project, which involved original research as well as interdisciplinary exchange through seminars and conferences, is available at http://appeel.fc.ul.pt/. © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 5 According to a review by Pigliucci (2007) entitled "Do we need an Extended Evolutionary Synthesis?", 82 the MS coincides with evolutionary genetics, as its foundations had consisted in a movement of 83 "crystallization" of a "theory of genes" out of the original Darwinian "theory of form" (p. 2744). 84 Pigliucci supported such a claim with a brief conceptual history of evolutionary biology, summarizing 85 how 20th Century Darwinism overcame Lamarckism, and how Mendelism was made compatible with 86 gradual change by means of statistical works by Fisher, Haldane and Wright (Ivi, p. 2744). He 87 described the major theoretical contributions by Dobzhansky, Mayr, and Simpson in the 1940s, and 88 then identified some missing elements in the MS, namely: development, studied separately by 89 embryologists (p. 2745); ecology, secluded away as a background condition of evolution (Ibidem); 90 implications of the '--‐omics revolution', and its relationships to neutralism and complex genotype--‐91 phenotype interactions (pp. 2745--‐6); and phenomena such as plasticity, evolutionary capacitance, 92 epigenetic inheritance (p. 2746). An EES would integrate a theory of form back into evolutionary 93 biology (p. 2745). Some "bits and pieces" or "recurring ideas" (p. 2746) that will be part of the EES 94 would be: evolvability, hinging on developmental systems' modularity and robustness (p. 2746); 95 phenotypic plasticity and the possibility of modes of evolution such as genetic accommodation (pp. 96 2746--‐7); epigenetic and multiple inheritance (p. 2747); complexity theory, revealing organizing 97 principles different from natural selection (Ibidem); and updated adaptive landscapes, in light of 98 work that reformulates their general shape (pp. 2747--‐8). Concluding the 2007 paper, Pigliucci 99 anticipated a new, complex, constructive process analogous to the MS itself, a progressive 100 "expansion of theoretical biology (in the broader sense of conceptual understanding of the 101 discipline's foundations)" (p. 2748). 102 Converging independently with Pigliucci, Müller (2007) identified a major deficiency of the standard 103 MS in the missing explanation of organismal form (p. 943). Müller explained that evo--‐devo, defined 104 as "a causal mechanistic approach towards the understanding of phenotypic change in evolution" (p. 105 945), has been focusing on the origin of phenotypic organization, going beyond genetics and gene 106 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 6 regulation to include "the dynamics of epigenetic interactions, the chemicophysical properties of 107 growing cell and tissue masses, and the influences of environmental parameters" (p. 944). Evo--‐devo 108 has, for Müller, three major theoretical themes – modularity, phenotypic plasticity, and evolutionary 109 innovation – that cross--‐cut its different approaches. Like Pigliucci, Müller talked about "major 110 departures" from the standard theory, that also constitute theoretical implications for extending the 111 MS: evolvability, not simply equated with the amount of genetic variation; emergence, accounting 112 for the appearance of phenotypic novelties that fuel natural selection; and organization, 113 substantiating the characteristic organizational features of phenotypic evolution, such as modularity, 114 homology, homoplasy, and body plans. 115 [FIGURE 1 HERE] 116 Soon after publishing their reviews, in July 2008 Müller and Pigliucci organized a meeting at the 117 Konrad Lorenz Institute in Altenberg, Austria, gathering some biologists who had written about the 118 extension of the MS, or were more or less willing to acknowledge such direction to their work 119 (Whitfield 2008; Pennisi 2008). Proceedings of the meeting were published two years later as the 120 book Evolution: The Extended Synthesis (Pigliucci and Müller 2010) echoing Julian Huxley's classic 121 (Huxley 1942, reprinted for the occasion). The introduction featured a summary diagram (Fig. 1.b) of 122 the chapters' themes,6 arranged as elements that extend the MS. The diagram is a useful tool to 123 analyze the EES proposal and its transformations through time (see below, Sect. 3). The 2010 124 diagram (Fig. 1.b) does not preserve Pigliucci's nor Müller's original lists. Pigliucci's "complexity 125 6 Besides Pigliucci and Müller, the other fourteen scientists at Altenberg were John Beatty ("Reconsidering the importance of chance variation"), Sergey Gavrilets ("High--‐dimensional fitness landscapes and speciation"), David Sloan Wilson ("Multilevel selection and major transitions"), Gregory A. Wray ("Integrating genomics into evolutionary theory"), Michael Purugganan ("Complexities in genome structure and evolution"), Eva Jablonka ("Transgenerational epigenetic inheritance" with Marion J. Lamb), John Odling--‐Smee ("Niche inheritance"), Eörs Szathmáry ("Chemical, neuronal, and linguistic replicators" with Chrisantha Fernando), Marc W. Kirschner ("Facilitated variation" with John C. Gerhart), Stuart A. Newman ("Dynamical patterning modules"), David Jablonski ("Origination patterns and multilevel processes in macroevolution"), Günter P. Wagner ("Evolution of evolvability" with Jeremy Draghi), and philosophers Alan C. Love ("Rethinking the structure of evolutionary theory for an extended synthesis") and Werner Callebaut ("The dialectics of dis/unity in the evolutionary synthesis and its extensions"). Müller contributed "Epigenetic innovation", whereas Pigliucci "Phenotypic plasticity". © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 7 theory" and "updated adaptive landscapes" and Müller's "emergence" and "organization" are not 126 shown. Indeed, the integrated theory of form hinging on the dynamic connection between genotype 127 and phenotype that both Pigliucci and Müller had outlined in 2007 does not exactly correspond to 128 the 2010 proposal. There, different problems are pointed to by several concepts, e.g., "genomic 129 evolution", "replicator theory", "niche construction". The EES will not be, eventually, (just) a theory 130 of form. Let us examine the pillars of this EES in some detail. 131 2. Conceptual pillars of the EES 132 Setting aside facts – such as "common descent" – that are not questioned by the main EES 133 advocates, I propose five categories in which the concepts represented in the diagrams of Fig. 1 134 would roughly fit: mechanisms such as epigenetic inheritance, genetic accommodation, or natural 135 selection, measures such as plasticity, variation or robustness, fields such as evo--‐devo, perspectives 136 such as niche construction, and derived applications of evolutionary models such as replicator 137 theory. I invite the reader not to take my categories too seriously: later I wil observe that not only 138 categories, but also concepts are subject to arbitrary choices and modifications, and I will provide 139 explanations for that. Accordingly, we cannot expect that my categorization of these concepts has 140 any stability or value other than the sake of an ordered presentation. Than being said, let us navigate 141 through the concepts by kind. 142 2.1. Mechanisms 143 Some conceptual pillars can be defined as mechanisms.7 Epigenetic inheritance is perhaps the best--‐144 fitting example. In the 1950s, epigenetics meant a family of hypotheses about cell state being 145 7 Philosophers of science have recently turned 'mechanism' into a technical term, the focus of a view of science called 'the New Mechanism', and an object of conceptual enquiry (Machamer, Darden and Craver 2000, and later works). The New Mechanism has stimulated, for example, discussions on whether or not natural selection and drift are evolutionary mechanisms (Skipper and Millstein 2005, Millstein, Skipper and Dietrich 2009, © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 8 determined not only by genetic states, but also by "auxiliary" functional states of the nucleus and the 146 cytoplasm, inherited from cell to cell through a non--‐genetic mechanism (Nanney 1958, 1959). 147 Epigenetic inheritance was proposed as an explanation for organismal processes such as oncogenesis 148 and aging of multicellulars (Lederberg 1958). Early radical claims were made that epigenetics 149 overthrows the MS by adding different rules of transmission, such as maternal effect and theoretical 150 reversibility (Løvtrup 1972; Ho and Saunders 1979). Epigenetics became really important later, with 151 the elucidation of its molecular groundings ushered by Robin Holliday (1987; see Haig 2004). Today 152 the molecular prototype of an epigenetic modification is DNA methylation inherited in cell 153 proliferation (Holliday 1979), and epigenetic inheritance is also studied at the organismal, inter--‐154 generational level (Grossniklaus et al. 2013). 155 Another example of a pillar--‐mechanism, this time located in the Darwinian 'core', is natural selection. 156 In the EES area we find multilevel selection, a mechanism that integrates different levels of selection, 157 each of which works on units that aggegate units at the lower level. The origin of the idea of 158 multilevel selection is traced back to Darwin trying to solve the puzzle of traits that are "good for the 159 group" while being disadvantageous for the individual: in Descent of Man (1871), Darwin proposed 160 selection among human tribes as a "straightforward solution" (Wilson 2010, p. 80--‐81) to the 161 evolutionary puzzle of the persistence of "high standards of morality" that decrease individual 162 fitness. All over the 20th Century, group selection underwent eclipses and rebuttals by mathematical 163 means, while multilevel selection was evoked for the level of species, the level of genes, and others. 164 More mathematical studies were made on the conditions of plausibility of multilevel selection 165 (Okasha 2006), and on the evolutionary origins of levels of selection – the "Major Transitions" 166 (Maynard Smith and Szathmáry 1995) – such as the origin of multicellularity, or colonial life, or the 167 origin of life itself. For Pigliucci (2009, p. 221), "it is now clear that several levels of the biological 168 Matthen 2010, Matthewson and Calcott 2011, Havstad 2011, Nicholson 2012). Here I use mechanism in a non--‐ technical, vernacular scientific sense. © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 9 hierarchy are, at least theoretically, legitimate targets of selection, from genes to individuals, from 169 groups of kin to populations to species" (see also Keller 1999). 170 2.2. Measures 171 Although phenotypic plasticity is sometimes referred to as a developmental process or a mechanism 172 (Pigliucci et al. 2006), plasticity may be better seen as a measurable property of a genotype 173 concerning the range of phenotypes that such genotype can produce in different environments 174 (Pigliucci 2010). The concept is not new: it was coined by Woltereck (1909) along with the notion of 175 reaction norm, i.e. the rule according to which the development of a phenotypic trait co--‐varies with 176 specific features of the environment. Scientists such as J. M. Baldwin, C. H. Waddington and I. I. 177 Schmalhausen anticipated that phenotypic plasticity of a trait would allow for phenotypic 178 accommodation to environmental inputs during development, followed – if inputs are sustained for 179 enough evolutionary time – by genetic accommodation, i.e. the intergenerational accumulation of 180 genetic changes that eventually reduce platicity of the trait (West--‐Eberhard 2003). According to 181 Pigliucci (2010, p. 357) "Phenotypic plasticity is now the paradigmatic way of thinking about gene--‐182 environment interactions [...] and one of the best studied biological phenomena in the evolutionary 183 literature". 184 Modularity and robustness are other genetically determined properties that appear, along with 185 plasticity, in the EES. 186 Modularity consists in the presence of modules, i.e. integrated structures that are repetitive, and 187 that tend to persist and get reused in evolution. Modules can occur in different contexts such as the 188 genome, individual morphogenesis, clades, broader phylogenies, at various scales. Modularity may 189 not be properly a measure, but it comes in degrees,8 and according to mathematical and simulations 190 8 Some people ue Herbert Simon's (1962) idea of near--‐decomposability as a model and a quantification of modularity. © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 10 studies it is expected to occur in huge superconnected networks such as the genome. Sometimes 191 modularity is coherent across two levels, genetic and phenotypic, when genetic modules affect only 192 a part of the phenotype with no deleterious pleiotropic effects on other parts (Müller 2007). But 193 modularity at one scale is not necessarily aligned to other scales. Modular patterns in the 194 phenotypes may also emerge at the phenotypic level, by the mechanics of cell differentiation in 195 which cells induce each other to assuming states in the multistable landscape of cell states (Newman 196 2010). Müller (2007) explains that sometimes when a "unit of phenotypic construction" remains 197 recognizable in anatomical architectures over evolutionary time, the molecular and developmental 198 pathways that construct the unit change. According to Wagner and Altenberg (1996), in the 199 phylogeny of animals modularity is most likely a derived state, the result of parcellation rather than 200 integration, with the open question of whether modularity emerged by natural selection. 201 Robustness measures the reliability of outcomes in the face of perturbations, both environmental 202 (e.g., temperature change) and internal (e.g., mutations). Genomes, biochemical networks, and 203 developmental processes can be more or less robust to various kinds of perturbations with respect 204 to some outcome (e.g., the phenotype, fitness). In development, robustness has long been known as 205 canalization (Waddington 1940): most perturbations of the developmental process have a temporary 206 effect that doesn't affect the phenotypic outcome. Only some kinds of perturbations in restricted 207 time frames can push the developing organism down a different developmental route. According to 208 Félix and Wagner (2008), a system may be robust to stochastic noise, environmental 209 change and genetic variation. Robustness to genetic variation includes robustness to mutational 210 variation and robustness to the effect of recombination between alleles at different loci. "Robustness 211 – Félix and Wagner write – is not an all--‐or--‐nothing property. It is a matter of degree" (p. 134). 212 Evolvability is understood in different ways (Pigliucci 2008a). On the one hand, evolvability has to do 213 with standing variability and also with heritability (Houle 1992), the standing genetic variance in a 214 population being a measure of the potential of that population to respond to natural selection, as 215 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 11 demonstrated by Fisher's fundamental theorem (1930). On the other hand, evolvability concerns 216 genetic structure and its ability to produce evolutionary novelties (Wagner and Altenberg 1996). 217 Another meaning of evolvability is related to 'key innovations' that make particular clades more 218 speciose or adaptable. In all cases, evolvability is the capacity of a system for evolution, therefore it is 219 the expected rate and amount of evolution correlated with certain characteristics. In some contexts, 220 the meaning of evolvability is narrowed down to the rate of adaptive evolution (vs. any kind of 221 evolution). 222 Plasticity, modularity, robustness, and evolvability are all measures that concern how natural 223 selection works in populations. It is possible that patterns of gain and loss of these properties are due 224 to natural selection (for adaptive plasticity, see Schlichting and Pigliucci 1998; Pigliucci et al. 2006; 225 Wund 2012). On the other hand, more or less evolvable populations of plastic, or modular, or robust 226 organisms will undergo different selective dynamics and trajectories. In any case, measures such as 227 plasticity, modularity, robustness, and evolvability are thus seen as new concepts, absent in the MS, 228 that explain how life evolves. 229 2.3. Fields 230 Some of the conceptual pillars are whole scientific fields. Population genetics, paleontology, and 231 natural history are familiar 'actors' in many historical accounts of evolutionary biology (Mayr and 232 Provine 1980; Gould 1980, 1982, 2002; Eldredge 1985, 1999), including Pigliucci's (2007, p. 2744; 233 2009, p. 220). Fields have their own history of change. For Pigliucci (2009), genomics started with the 234 view that "once we 'decode' the genome of an organism we somehow gain a universal key to 235 understanding its biology" (p. 223). This first phase was, for Pigliucci, "squarely within the conceptual 236 framework of the rather gene--‐centric MS". Then genomics and other "--‐omics" fields renewed 237 themselves by turning to system--‐level properties of entire networks of gene products. Fields have 238 their own complex structure, subfields, and hybridizations. Evo--‐devo, as Müller (2007) says, is not 239 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 12 only a whole approach to evolution, rather it is itself composed by four approaches or 240 "programmes": comparative embryology and morphology, evolutionary developmental genetics, 241 experimental epigenetics, and the theoretical and computational programme. Complexity theory and 242 network theory, listed in the EES, are mathematical fields that are applied in many domains of 243 biology and beyond. Ecology is called into question as a proper scientific field (2007, p. 2745; 2009, p. 244 221), not as a mere attention to environmental aspects. Pigliucci (2007, 2009) argues that the field of 245 evolutionary ecology "barely scratches the surface of the field of ecology at large" (2009, p. 224), and 246 wishes for some kind of future union between ecology and evolutionary biology. 247 2.4. Perspectives 248 Some conceptual pillars are better seen as theoretical perspectives that can be adopted in the 249 construction of evolutionary models. This is the case of updated adaptive landscapes and niche 250 construction. Both perspectives are related to mathematical constructions. Landscapes are a 251 geometrical representation of properties of a space of traits (Fusco et al., 2014). The geometrical 252 representation and the conveyed properties become a perspective to set up evolutionary problems 253 in empirical research and modeling. Niche construction is firstly a perspective pointing to biotic 254 ecological impact and consequent natural selection feedbacks, and it inspires the construction of 255 mathematical models or, more often, the modification of existing ones. 256 Gavrilets (1997) argued that Wright's (1932) intuition of fitness peaks and valleys was way too 257 simplified in light of the degree of connectedness of high--‐dimensional spaces. Gavrilets applied 258 percolation analysis (originally developed in physics) to the space of possible genetic combinations of 259 a population, showing that such space will surely be super--‐connected: any fitness value will certainly 260 be the fitness value of a bundle of chains of combinations that are connected by means of single--‐261 allele substitutions. In other words, for each fitness value there will be a 'giant component' extending 262 all the way throughout the space of possible combinations. The fitness function of a giant component 263 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 13 can be imagined as 'holey' because, although any pair of combinations in the giant component is 264 connected by means of a series of single--‐allele neutral substitutions, there are pairs of combinations 265 that are connected by very long chains. Gavrilets used these compelling mathematical considerations 266 as a theoretical justification for his low--‐dimensional neutral models of speciation (2004). Pigliucci 267 (e.g. Pigliucci and Kaplan 2006 chp. 7; Pigliucci 2007, 2008b; Pigliucci and Müller 2010) was more 268 interested in possible direct implications for adaptation. He took holey landscapes as a perspective 269 revealing the plausibility of neutral genetic exploration and fast switching from one giant component 270 to another (called 'extra--‐dimensional bypass' by Gavrilets). In this respect, perhaps more appropriate 271 than Gavrilets's speciation works are Wagner's studies on neutral networks, where a phenotypic 272 trait, instead of fitness, is mapped on the multi--‐dimensional space of genetic combinations (e.g. 273 Wagner et al. 1994; Wagner 2008, 2009). 274 Niche construction captures the basic observation that organisms impact and also actively construct 275 their and others' environment (Darwin 1881). Richard Lewontin (1978, 1983) and John Odling--‐Smee 276 (1988) were among the authors who began to point out a 'lack of modeling' of the widespread 277 phenomenon of niche construction in the mathematical core of evolutionary theory, i.e. population 278 biology. Dawkins's (1982) concept of 'extended phenotype' was an incomplete perspective (Odling--‐279 Smee et al. 1996, p. 295) in considering niche construction only as a product – not as a source – of 280 natural selection. Since the the 1990s the niche construction perspective has been a collector of 281 examples brought to the attention of evolutionary theorists. Evolutionary niche construction models 282 (Odling--‐Smee et al. 1996; Laland et al. 1996, 1999; Odling--‐Smee et al. 2003) were obtained by 283 modifying consolidated two--‐locus multiplicative models in population genetics. The introduction of 284 feedback from gene frequencies to selection pressures (influencing, in turn, gene frequencies) yields 285 significant novelties in the dynamics. Therefore, niche construction models have been hailed as an 286 important step forward in evolutionary modeling. 287 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 14 2.5. Derived applications 288 Finally, replicator theory – as presented by Fernando and Szathmáry in Pigliucci and Müller (2010) is a 289 "lateral extension" of the MS, a further kind of concept.9 It transfers a replicator--‐based view of 290 natural selection (Campbell 1960; Dawkins 1976, 1982) to different, previously non--‐evolutionary 291 disciplines such as chemisty, neuroscience, and linguistics. Fernando and Szathmáry explore, for 292 instance, the conditions for the existence of chemical replicators able to undergo natural selection, in 293 light of the emerging field of systems chemistry. They recognize several candidate types of 294 replicators also in the human brain: synaptic replicators, topological neuronal replicators, and 295 dynamical neuronal replicators. Building on the tradition of 'neural Darwinism' (Edelman 1987; 296 Changeux 1985), Fernando and Szathmáry report several kinds of simulations and reflect on whether 297 and how we can consider thought as a process of blind variation and selective retention (Campbell, 298 cit.). They also introduce language in this framework, as a means of inter--‐brain neuronal replication. 299 If, as we said, these works can be considered as tentative applications of the MS partly outside its 300 domain, it is also true that they require conceptualizations and operationalizations that are 301 considered eventually useful to biology. Attempts at extending the applicability of natural selection 302 raise, for example, the common problems of defining heredity and fitness, of explaining how 303 "unlimited heredity" arises from "limited heredity", and of showing the evolution of evolvability. As 304 Fernando and Szathmáry say, their studies can "contribute to the depth of the theory", not only to its 305 lateral extension, by shedding "new light on evolvability, exploration distributions in evolution, and 306 the interplay of Lamarckian and Darwinian mechanisms, but strictly within the constraints of 307 genetically based evolution..." (p. 242). "Exploration distributions" is a term from the theory of 308 algorithms. Computer algorithms "explore" a space of possible combinations by realizing some of 309 them through time. These simulations are used to study how evolution explores phenotype space, 310 and to explain the emergence of correlations between different phenotypic traits (Toussaint 2003). 311 9 Other examples, reported by Callebaut (2010) as not sufficiently emphasized in Pigliucci and Müller (2010), are evolutionary economics, evolutionary medicine, and cultural evolution. © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 15 3. Restless concepts 312 As we shall see in the next section, the EES is first of all a "metascientific view" of such a broad field 313 as evolutionary biology. Hard obstacles will be encountered by someone who, like EES advocates or 314 the MS architects, wants to formulate a description of what is it to do research in evolutionary 315 biology yesterday, today, and tomorrow. A strong dynamism in the set of EES concepts is thus to be 316 expected. To look at how concepts wander throughout publications and diagrams, an apparently dull 317 task, can be useful here. 318 Some concepts are stably there, e.g. evolvability (coupled, only in 2009, with modularity), epigenetic 319 inheritance, and plasticity and accommodation (which also constitute one of Pigliucci's specialties, 320 e.g., Schlichting and Pigliucci 1998; Pigliucci 2001; cf. Scheiner 1999). Evo--‐devo, genomics, and 321 multilevel selection are included since 2009 with small, essentially metatheoretical changes (evo--‐322 devo becomes qualified as "theory" in 2010, while multilevel selection loses such qualification; 323 "genomics and network theory" switch to "genomic evolution"). Some elements are particularly 324 labile. Complexity theory is dropped in 2010. Replicator theory only shows up in 2010. Ecology, listed 325 as a missing element of the MS by Pigliucci (2007), participates to the EES only in the 2009 diagram. 326 Contingency even jumps from being an element of the EES in 2009 to being a concept of the MS in 327 2010. Some concepts slip in in 2009 to be conserved in 2010, such as niche construction. The set of 328 candidate concepts for an EES mutates through the different papers and works, even works by the 329 same person – see Sect. 1 and Fig. 1. Of course, cartoon diagrams must be taken with a grain of salt: 330 they are idealized and represent only some aspects of the EES discourse. That being said, in this 331 search for the best arrangement of evolutionary concepts, many will recognize a persistent dose of 332 arbitrariness.10 For instance, evolutionary mechanisms (see 2.1) are arranged by EES proponents in 333 10 Since I am going to criticize an account of the EES based on lists of concepts, I don't embark in the task of pointing out 'elements' (see classification in Sect. 2) that arguably extend the MS but are not considered in any EES work. There would be many examples, the most important being horizontal gene transfer (Boto 2010), symbiogenesis, and 'horizontal evolution' in general (Kutschera and Niklas 2004, Gontier 2007). In a previous © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 16 just one of the many possible alternative ways. Notice that the historical counterpart of epigenetic 334 inheritance, which would be genetic or germline inheritance, is missing from EES diagrams. Instead 335 we find Mendelism and Mendelian inheritance, but these are not alternative physiological 336 mechanisms of inter--‐individual passage of traits: they rather describe a trans--‐generational traits 337 distribution pattern11. Then, natural selection and multilevel selection are depicted as distinct pillars, 338 but, granted that multilevel selection is accepted (Keller 1999), we may well argue that such 339 acceptance implies the unity of selection, i.e. that multilevel selection is natural selection, and that 340 natural selection is or can be multilevel. The split of natural selection and multilevel selection as two 341 distinct pillars seems thus more of a way of marking certain theoretical studies than an addition of 342 discrete new mechanisms as it is always presented. Indeed, the reflection on units and levels is 343 inherent to evolutionary biology: it has never stopped since Darwin.12 Interlevel dynamics are a 344 pervasive issue, beginning with genetic selection vs. phenotypic selection which must be correlated 345 over various time scales. Genotypes and phenotypes entertain non--‐linear relationships as shown for 346 example by other mechanisms listed in the EES: phenotypic accommodation (i.e., adjustment, 347 without genetic change, of variable aspects of the phenotype following a novel input during 348 development) and genetic assimilation (loss of dependence on environmental cues, Pigliucci et al. 349 2006). Accommodation is depicted as stably associated with plasticity, whereas we might regard it as 350 a further example of the multilevel complexity of the single mechanism of natural selection. We have 351 seen that plasticity, modularity, robustness, and evolvability might not be evolutionary mechanisms 352 footnote I already cited macro--‐evolutionary extensions of the MS that are poorly considered by EES advocates (Serrelli and Gontier forthcoming). 11 To be fair, "Mendelian" applies also to the modern biological chromosomal theory of inheritance, not merely to the pattern inferred from crossing as Mendel reported in 1866. On the one hand, however, "Mendelian" is associated by EES advocates themselves to population genetics, and in that context "Mendelian" precisely points to the basic pattern of trait transmission. On the other hand, this is just one of the cases of polysemy that occur both in the EES and in this response of mine, polysemy that eventually comes out on the side of my more fundamental position about the serious paucity of conceptual analysis to account for evolutionary biology. 12 Moreover, the reflection on units and levels is only one of the many lines of conceptual work on natural selection, with repercussions for empirical research. We would probably be able to capture crucial positions and passages from any line of reflection and consider them as pillars. For example, is natural selection alternative to drift? Is it a force? Is it distinguishable from sorting? I think we wouldn't be able to crystallize 'additional pillars' out of these debates without a significant amount of arbitrariness. © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 17 but, rather, measures that improve understanding of natural selection. Their isolation as EES 353 conceptual pillars seems justified by the fact that they are also attentions of an emerging way of 354 conceiving variation in evolution. However, other conceptual arrangements could be possible in 355 which these measures don't stand out as pillars. For example, we might suggest their subsumption 356 into multilevel selection by understanding them as interlevel phenomena. As Müller (2007) notices, 357 modularity "is pervasive at all levels of biological organization" (p. 944), and there can be various 358 correlations among modules that occur at different scales in biochemical networks and physical 359 processes of differentiation in development. Not by chance, modules have been proposed as units of 360 selection (Wagner 1996). Robustness is even more constitutionally an interlevel property, concerning 361 the stability of association between genotype and phenotype. Finally, the two most important 362 meanings of evolvability both involve the genotype--‐to--‐phenotype map. Thus we might see the four 363 measures as aspects of multilevel selection, but earlier we questioned the 'pillar' status of multilevel 364 selection itself, so in the end everything might be collapsed back into natural selection. 365 If the set of concepts for an EES seems so dynamic over time, something even more radical happens 366 to the Darwinian core and to its supposed extension by the MS. If we focus on the Darwinian core in 367 Fig. 1, natural selection persists, but the other ingredients vary: in 2009 there is common descent 368 (Fig. 1.a), whereas in 2010 variation and inheritance (Fig. 1.b). As for the MS, its additions to 369 Darwinism change as well. According to Pigliucci (2009) the MS adds natural history, Mendelism, 370 population--‐statistical genetics, and paleontology. Pigliucci and Müller (2010) only preserve 371 Mendelian inheritance and population genetics, complementing them with gene mutation, 372 contingency, and speciation and trends. I have been even too long in demonstrating that, hence, the 373 arrangement of concepts proposed by the EES (including the arrangement proposed for the MS) is 374 not only changeable, but also ostensibly arbitrary. The shaky identity of the MS may be a problem for 375 the EES account that precisely depicts the MS as a stable set of constraining ideas, but this will be 376 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 18 addressed in section 5. In what follows I shall talk about discussions about the EES, and explore some 377 of the intrinsic reasons that imply arbitrariness, disagreement, and sometimes confusion. 378 4. The EES as a tricky metascientific description 379 We have reviewed most of the concepts listed by EES advocates. In Fig. 1 they are arranged in 380 successive expansions. Notice that these expansions are meant to show not only cumulative growth 381 of knowledge about evolution, but also the various transformations of evolutionary biology as a 382 scientific field. The different circles aim at being representative of how working in evolutionary 383 biology was, is, and will be at different times. The EES is thus, first of all, a metascientific claim (i.e., a 384 claim about science), then a scientific claim (i.e., a claim about how life evolves). In fact, ongoing 385 controversies on the EES mingle scientific and metascientific aspects. Single concepts of the EES have 386 been questioned with respect to their scientific validity, relevance, or innovativeness (Reiss 2011). 387 Coyne (e.g., 2009) questions, for example, the real evolutionary incidence of epigenetic inheritance 388 due to the short life of epigenetic changes over generations. Some pillars create different factions 389 concerning their compatibility with long--‐standing knowledge (e.g., for evo--‐devo, Minelli 2010 vs. 390 Laubichler 2010). But many other issues are more exquisitely metascientific: they are about the 391 science, not the world. Fields such as "population genetics" or "ecology" or "evo--‐devo" that are 392 listed among EES conceptual pillars are metascientific concepts rather than scientific ones (more will 393 be said on this below). Another purely metascientific debate is the one concerning the age of 394 'pillars': claims for additions to the MS are also claims for the long absence of some ingredient, for 395 example ecology, from the field of evolutionary biology. Such absence is typically contested by 396 groups of scientists who claim to have always taken ecology (or whatever pillar at hand) into 397 consideration, or who point out forerunners. The timing of virtually each and every concept is a 398 matter of metascientific quarrel between different members of the scientific community. There is 399 also a more fundamental disagreement about the EES as such. Müller and Pigliucci (2010) observe 400 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 19 two opposite reactions to the EES: the "nothing--‐substantially--‐new" position and the "more--‐change--‐401 is--‐needed" position. The first position is seen as being represented by scientists such as Douglas 402 Futuyma and Michael Lynch.13 Futuyma (2011, 2014) thinks that evolutionary biology had absorbed 403 and incorporated discoveries throughout its history, without the need for a formal reconsideration of 404 evolutionary theory, and Lynch (2007) sees a multiplication of things to explain more than of 405 explanations. The second position, expressed in papers such as Craig (2010, 2011), is against 406 extending the MS because elements such as evo--‐devo would completely overthrow it: the MS would 407 not be amendable. Although some of the cited workers actually have nuanced opinions, some of 408 them did indeed express themselves in sharp contrast with the EES through various media (e.g., 409 Coyne 2009). Proponents of the EES usually explain away such a diffuse dissent by the conservative 410 inertia or active homeostasis of science, 'paradigmatic' almost in a Kuhnian sense. In any case, 411 metascientific descriptions seem difficult to achieve and exposed to controversies. 412 4.1 The scientist--‐field disproportion problem 413 An obvious obstacle to the achievement of a metascientific consensus is what could be called the 414 scientist--‐field disproportion. Evolutionary biology is vast in terms of involved people and labs all over 415 the world, with their diversity and ever--‐changing boundaries. All sorts of science are being done in 416 the world: do they fit the mind and the reach of one or few experts? How can we know what all 417 those people are doing? Pigliucci (2009), to explain shifts in his list of concepts (Fig. 1), acknowledges 418 the Altenberg meeting as an occasion for him to expand his thinking about evolutionary theory. 419 Taking the cue from this, we ought to think that, in general and inevitably, concepts are included by 420 the author partly as a function of contingent biographical and professional factors, such as the 421 particular field of specialization, the network of professional contacts, the encounters that happen, 422 or even some kind of personal taste. Factors like these are also subject to change over lifetime. All 423 13 Other protagonists are, e.g., Coyne (Hoekstra and Coyne 2007, Coyne in Pennisi 2008 and in Whitfield 2008), Hall (2000), Minelli (2010). © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 20 this speaks about the disproportion between any scientist's point of view and the necessary task of 424 mapping the field, at any time in history.14 Just think to how huge and fast--‐growing the scientific 425 literature is today. A metascientific view aspires to describe the web of networks of researchers and 426 labs that constitute evolutionary biology, i.e., people, along with their actions and knowledge, their 427 instruments, the different media and various kinds of connections among them, and also, in part, the 428 larger contexts in which they work and operate. When we are interested in an empirical concept 429 such as phenotypic plasticity, then, we want to know for example where, when, how, and how much 430 phenotypic plasticity was effectively studied in relation to evolution. And it is not even enough to 431 know how frequently phenotypic plasticity is mentioned, or who are the most cited 'experts' of it. 432 Before being able to demonstrate that plasticity is involved in the change of how evolutionary 433 biology is practiced, we need to deal with how phenotypic plasticity is integrated in scientific 434 practice, what is its incidence and role. How has the understanding of some concepts changed? And 435 what is the importance of concepts in scientific work in different contexts and periods? In other 436 words, how much research is theory--‐engaged and theory--‐driven (Scheiner 2013)? The fundamental 437 problem of logical analyses of science is that scientists do not live inside theories, rather, at any 438 particular moment in time, they have different versions or pieces of theory, with which they 439 entertain diverse relationships. EES advocates have persisted in describing Darwinism, the MS, and 440 the EES as nested sets of concepts and ideas, but evolutionary biology in 1980, in the 1930s, and in 441 any moment in history is a working scientific community that has to be studied under more aspects. 442 While rigorous methods such as meta--‐analysis are used to combine available scientific evidence, 443 rigorous ways of knowing the scientific community seem scarcer. 444 14 To the scientist--‐field disproportion we will add, in Sect. 4, the 'flag effect': any scientist's claims are part of socio--‐epistemological and socio--‐economical dynamics where he or she has needs, aims, open accounts. © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 21 4.2 The scientific--‐metascientific mix problem 445 We have seen that elements as heterogeneous as, for example, natural selection, modularity, and 446 paleontology constitute a mix of empirical and metascientific claims. Paleontology is actually one of 447 the fields in which modularity can be studied (L.A.B. Wilson 2013), and paleontology provides and 448 tests macroevolutionary models in which natural selection is more or less important. The logic of 449 addition, in a sense so important in the "extension" approach of the EES, hardly works in an 450 assemblage of scientific ideas (like natural selection) and metascientific ideas (like paleontology). It is 451 true that some concepts seem one piece with fields, since they originate, at least in part, as 452 generalized implications of particular fields. Evolvability, emergence, and organization are, for 453 example, considered by Müller (2007) as general theoretical implications of evo--‐devo.15 But fields are 454 ways of doing science, not scientific concepts themselves. Indeed, any alleged implication (e.g., 455 evolvability) of a particular field implication (e.g., evo--‐devo) is studied also by other fields, that in 456 turn can share or borrow inspirations for their theoretical models. On the other hand, fields can 457 cross--‐adopt ideas and concepts while remaining largely separated. Despite statements about niche 458 costruction being an example of "how ecology and evolutionary biology can be integrated" (Pigliucci 459 2009, p. 223), for example, existing niche construction models are in fact pure population genetics 460 models.16 Furthermore, long--‐standing fields can deal with concepts that are relatively recent. Take 461 for example population genetics and evolvability. The diagram in Fig. 1 misleads about how much 462 evolvability is integrated into (or even born out of) preexisting fields. Population genetics is often 463 stereotypically associated with its initial scientific accomplishment of showing that "several discrete 464 Mendelian genes can cumulatively produce the effect of a continuous, Gaussian distribution of 465 phenotypes" (Pigliucci 2009, p. 220). Mendelism is thus the founding assumption of population 466 genetics. But population genetics is an enduring empirical and theoretical field proceeding in the 467 15 We have seen with Pigliucci (2008a) that there are different kinds and sources of evolvability. 16 Examples of integration between ecology and evolution are growing fast, but not where Pigliucci looks at (Loreau 2010). © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 22 development of more and more tools (Hartl and Clark 2007) that handle, or even uncover, many of 468 the phenomena that are enlisted in the EES area, such as evolvability, multilevel selection, 469 phenotype evolution. Pigliucci himself (2009) says that multilevel selection is essentially an 470 "expansion of the mathematical theory underpinning evolutionary biology" (p. 221). Multilevel 471 selection may thus be seen also as a part of population genetics, a fruit of the natural growth of a 472 mathematical field.17 On the other hand, some models can be insensitive to specific mechanisms, for 473 example quantitative genetic models of phenotypic evolution stand largely invariant with respect to 474 the particular development mechanisms (Pigliucci et al. 2006). Finally, hierarchical relationships 475 among fields are another important aspect. For example, complexity theory and network theory can 476 be employed by genomics, but also by evo--‐devo or ecology, or even by paleontology, because of 477 their generality. It is true that complexity theory and network theory are autonomous fields, but 478 their introduction into evolutionary biology looks more like an integration into the methods of 479 existing fields than the addition of new fields. Many new measures and mechanisms happen to be 480 introduced in this way. The EES is not always clear on the distinction between scientific and 481 metascientific concepts. Pigliucci (2009, p. 222), for example, tried to attribute to each and every 482 "component of the ES" a degree of "conceptual maturity" and a degree of "empirical support". 483 Relying on Gould's (2002) triadic view of evolutionary theory, Pigliucci also tried to determine the 484 impact of every EES component upon natural selection's agency, efficacy and scope. These are 485 interesting attempts, but EES components are logically heterogeneous, which makes them hardly 486 comparable with respect to innovative load or degree of empirical support. Empirical support for 487 measures like plasticity is a different issue than for fields like evo--‐devo, or perspectives like niche 488 construction, or mechanisms like epigenetic inheritance, or tranfers like applications of replicator 489 theory. Measures are carried out. Old and new fields incorporate measures and perspectives and 490 probe the evolutionary relevance of mechanisms by means of theories of other fields. When 491 17 Notice that past and present important population geneticists, like for example Timothy Prout, do not agree with multilevel selection being a part of population genetics. This is just a further example of multiple construability of a conceptual scheme of evolutionary biology. © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 23 responding to the claim that "ecology was never integrated in evolutionary biology" one can go 492 metascientific and show off a field like evolutionary ecology, existing since the 1960s; another can go 493 scientific and point out the widely known roles of ecological factors in speciation or macroevolution. 494 In this way, the mix of metascientific and scientific claims can create confuse discussions. 495 Metascientific claims are also claims about history. Consider Pigliucci's claims quoted above: the MS 496 is a paradigm and a conceptual framework that goes back to the 1940s, etc.; it was the crystallization 497 of a theory of genes, and it is missing some important pieces that are being revealed today; indeed, 498 we do need an EES. These are all metascientific claims, all historical, often oriented to the future. 499 This creates a double chronology that has to be taken into account when we deal, for example, with 500 the EES. By EES we mean, on the one hand, the claims by EES advocates, and, on the other hand, one 501 of the historical stages of evolutionary biology that the advocates describe. A further complicaton of 502 metascientific claims is that they combine description and prescription: while they are meant to 503 capture the present and past situation of the field, they also suggest future directions or point out 504 certain ways of doing science that are more promising. The double chronology and the description--‐505 prescription duality are easily a source of ambiguities of metascientific claims. Is an EES already 506 achieved? If so, since when? Or are we instead working on it? Or is the EES a future prospect still to 507 come? And, in the latter case, is extension a normative or a descriptive claim (that is, does it concern 508 what scientists do or what they should do)? Understandably, EES advocates seem to oscillate 509 continually among these possibilities. Pigliucci (2007) argued for the need for an EES, and qualified it 510 as forthcoming (p. 2646). For Müller (2007) evo--‐devo is an already different understanding of how 511 development evolves, while its more general and deep implications are often overlooked. For 512 Pigliucci and Müller (2010), new concepts are part of the current "practice" of evolutionary theory, 513 but "Which of these will actually coalesce into a new kind of synthesis, augmenting the traditional 514 framework, is a major challenge for the theorists of today" (p. vii). There is a "multifaceted reseach 515 program" called the Extended Synthesis (p. 3); however, "an expanded theory of evolution [is] a 516 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 24 work--‐in--‐progress" (Ibidem), and the "current framework" has central tenets and assumptions yet to 517 be relaxed (p. 4): "individual tenets of the Modern Synthesis can be modified, or even rejected, 518 without generating a fundamental crisis in the structure of evolutionary theory" (p. 10). The 519 prevalent position seems to emerge from these oscillations that the EES is something already here in 520 practice and needing acknowledgement; at the same time, the EES is something whose existence 521 requires a kind of conceptual, logical structure. The structure of the EES is still to come, and has to be 522 worked out by theorists. Ambiguities like these are, I think, intrinsic of metascientific claims. 523 If EES theorists admit their uncertainties about what exactly the EES is or will be, they often seem 524 secure about what the MS is or was. Perhaps the time distance between a metascientific claim and 525 its target confers a sense of stability. Narratives of the MS are dry and standardized (see below, Sect. 526 4), but the underlying view on the matter is more shaky than it may seem. Metatheoretical terms are 527 expected define what kind of theoretical 'thing' the MS is. For example, the MS is said to be a 528 "conceptual framework" resulted from "the integration of several strands of evolutionary thought" 529 (Pigliucci and Müller 2010, p. 3). It is also a set of claims (p. 5) or "tenets" that, however, "can be 530 modified, or even rejected, without generating a fundamental crisis in the structure of evolutionary 531 theory" (p. 10). The MS is also a theory (p. 3), a research program (p. 3), and a set of restrictions (pp. 532 13--‐14). The MS is defined as the "current paradigm" (Pigliucci 2007, p. 2743; Pigliucci and Müller 533 2010, pp. 3, 14) but, at the same time, Pigliucci states that the only paradigm shift had taken place 534 with Darwin, at the origin of biology (Pigliucci 2007, p. 2748; see also Greene 1981). Metatheoretical 535 terms for the MS are thus diverse and partly conflicting.18 536 Particular weight is given to terms such as "central tenets" (Pigliucci and Müller 2010, p. 4, 5) to 537 convey the sense that the MS was a restrictive consensus on a structure made of conceptual pillars. 538 18 Other scholars employ still different terminologies. Scheiner (1992, 1999) for instance identifies two "central paradigms" in modern biology: the Modern Synthesis and the Molecular Synthesis. Syntheses are critical periods in which groups of relevant disciplines become focused on the same research program. For Scheiner, modern biology is undergoing a Final Synthesis between the two central paradigms, and this endeavour will be driven by the evolutionary side which has a larger pespective and is more theory--‐driven than the techique--‐ driven Molecular Synthesis. © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 25 As we saw above, however, the set of concepts that are taken to represent the MS is not fixed. 539 Besides, the evidence for such restriction doesn't seem systematic and fully convincing. Pigliucci and 540 Müller, in their introduction to the EES book (2010), take one quotation from the beginning of a 541 major textbook (Futuyma 1986, p. 12) as evidence for the narrowness and closure of the MS: 542 The major tenets of the evolutionary synthesis, then, were that populations contain genetic 543 variation that arises by random (i.e., not adaptively directed) mutation and recombination; 544 that populations evolve by changes in gene frequency brought about by random genetic 545 drift, gene flow, and especially natural selection; that most adaptive genetic variants have 546 individually slight phenotypic effects so that phenotypic changes are gradual (although some 547 alleles with discrete effects may be advantageous, as in certain color polymorphisms); that 548 diversification comes about by speciation, which normally entails the gradual evolution of 549 reproductive isolation among populations; and that these processes, continued for 550 sufficiently long, give rise to changes of such great magnitude as to warrant the designation 551 of higher taxonomic levels (genera, families, and so forth) (Futuyma 1986, p. 12, cit. in 552 Pigliucci and Müller 2010, p. 9). 553 Pigliucci and Müller seem to think that Futuyma's summary effectively represents the MS as a 554 narrow 'tunnel vision' for evolutionary biology. But another quote, taken from an advanced point of 555 the very same edition of Futuyma's textbook, is cited in Alan Love's chapter of Pigliucci and Müller's 556 book as a "defense of the Modern Synthesis perspective" describing Neo--‐Darwinism as open and 557 intrinsically integrative: 558 The power of neo--‐Darwinism lies in its generality of explanation. But like most general 559 theories, it is highly abstract. It gains full explanatory power when concepts such as gene 560 frequencies and selection are given empirical content by applying them to real features of 561 real organisms: behavior, life histories, breeding systems, physiology and morphology. When 562 this is done, hovewer, new questions appropriate to those particular features emerge and 563 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 26 context--‐specific factors must be added to the theory (Futuyma 1986, p. 440, cit. in Love 564 2010, p. 416). 565 Notice that Love (2010) distinguishes between theory content and theory structure, with the 566 possibility of different "presentations" to different aims. Futuyma's paragraph reveals, for Love, "a 567 commitment to a broad rather than narrow representation of evolutionary theory" (my emphasis, 568 see also Love 2012). 569 The definition of the MS found in EES advocates is thus, at once, uncertain and self--‐confident. It is 570 uncertain with respect to its metatheoretical status and the list of component concepts. It is 571 confident in the conviction that the MS is well representable as a set of concepts, and also that the 572 MS was a restriction of research questions by means of a narrow consensus on a few assumptions. 573 But even in this respect we have different positions and anecdotical evidence. As we shall see (Sect. 574 5), the view of the MS resonates strongly with the account that was forcefully defended by Ernst 575 Mayr especially during the 1970s (Mayr 1973). EES advocates seem to take Mayr's version of the 576 story at face value: the MS was a channeling of research questions and explanations, by means of a 577 generalized agreement on a few key concepts and mechanisms. The history of biology, however, 578 warns us against taking metascientific claims too literally. We saw important factors of complication 579 in achieving a solid metascientific view. Now, traveling back in time to the MS, we will see that 580 additional biases apply. 581 5. Useful flags: Syntheses in historical perspective 582 Ernst Mayr wrote: 583 The term "evolutionary synthesis" was introduced by Julian Huxley [...] to designate the 584 general acceptance of two conclusions: gradual evolution can be explained in terms of small 585 genetic changes ("mutations") and recombination, and the ordering of this genetic variation 586 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 27 by natural selection; and the observed evolutionary phenomena, particularly 587 macroevolutionary processes and speciation, can be explained in a manner that is consistent 588 with the known genetic mechanisms (Mayr in Mayr and Provine 1980, p. 1). 589 We should contrast Mayr's account of the MS – taken at face value by EES advocates – with what 590 historians of biology discover about the MS.19 Cain (2009a), for example, focuses on the pragmatic 591 and strategic utility of claiming, back in the 1930s, to be part of a modernizing team (see also Provine 592 1992, cit. in Delisle 2011, Smocovitis 1996). To the 'architects', the claim was a strategic move in 593 many ongoing battles, and personally useful to their careers. 'Outsiders', as well, employed the MS in 594 'David and Goliath' narratives to muscle their way through. The idea that the MS is there as a certain 595 object was born and cultivated for specific reasons in those years. Meanwhile – historians show – 596 architects of the MS such as Huxley, Simpson, Dobzhansky, and Rensch held different research 597 agendas or even "incommensurable epistemological frameworks" (Delisle 2011, p. 57; see also Cain 598 2003), and paradoxically the advertised narrow set of concepts ended up by being an obstacle to the 599 advancement of these agendas. Cain (2009a)20 argues that traditional historiography, following the 600 lead of MS claims, has been affected by historical realism on the MS, and that many historical studies 601 of the synthesis period create forced links between anything that was happening and that alleged 602 overarching object, the MS. History can actually be told in very different ways – for example, Cain 603 thinks that while an evolutionary synthesis at the theoretical level was proclaimed, a synthesis of 604 taxonomy and systematics (old and new) was substantially more important. The 'constructed' nature 605 of the MS was epitomized already by Burian (1988) when he defined the MS as a ''moving target'', 606 with regards to both the list of its possible 'architects' and the boundaries of its research agenda. 607 19 Enlightening examples, beside cited Joe Cain, are Sahotra Sarkar, Betty Smocovitis, Michael Dietrich, William Provine, David Depew, Richard Delisle. 20 Cain wrote many papers describing the overall situation in the MS period (2000, 2002a, 2009a, 2013). He also published equally interesting monographic studies focused on personalities such as Simpson (Cain 1989, 1990, 1992), Sewall Wright (Cain 2007), Julian Huxley (Cain 2010), Ernst Mayr (Cain 1994, 2009b), Theodosius Dobzhansky (Cain 2002b). Notice that, of course, Cain is just a telling example and that historians themselves are not monolithic at all in their consideration of the MS (cf., e.g., Sarkar 1992, 2004). © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 28 A step in the 'objectivization' of the MS was the 1980 Conference on the Evolutionary Synthesis 608 whose proceedings are Mayr and Provine (1980). Ernst Mayr was a very influential figure throughout 609 20th Century evolutionary biology. He (1973) had battled to acknowledge "the naturalists" as he 610 called them (e.g., zoologists, paleontologists) against an account of the MS that he saw as too 611 imbalanced in favor of geneticists and mathematicians (targeting, e.g., Provine 1971). An important 612 moment for the establishment of Mayr's own view of the MS was the 1980 Conference. Mayr 613 wanted to clarify "the sequence of events [1936--‐1947] leading to the synthesis, and to identify the 614 factors responsible for the preceding disagreements" (Ibidem). But despite Mayr's 'general 615 acceptance' view of the MS, even a cursory reading of Mayr and Provine (1980) reveals a diversity of 616 stories and visions of the MS across points of view, disciplinary backgrounds, geographical positions. 617 As Provine noticed, the 1980 Conference and proceedings are not a great example of consensus and 618 agreement on a small set of concepts, despite Mayr's efforts. In the Epilogue, Provine wrote: 619 One note of unanimity at the conference may perhaps need to be revised. Although all 620 participants seemed to agree that an evolutionary synthesis had occurred, they may have 621 had different syntheses in mind. The evolutionary synthesis may therefore have appeared 622 more cohesive during the conference than it actually was (Provine in Mayr and Provine, p. 623 408). 624 There is not much consensus on the proclaimed consensus, after all. 1980 was more the attempted 625 construction of a consensus than it was the account of an already achieved agreement. 626 We must derive two lessons for our interpretation of the EES debate. 627 First, Ernst Mayr, along with others, produced, iterated, and defended for specific purposes the view 628 of the MS that is now adopted in the EES. The Modern Synthesis was, first of all, a useful flag. The 629 'conceptual pillars' must not be understood as a faithful account of the scientific community at any 630 time, but rather a manifesto flag for the 'architects' in their respective times. This awareness, along 631 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 29 with inconsistencies and shortages of the available descriptions of the MS, may make us more 632 cautious in objectivizing the MS. 633 Second, EES claims may be analogized to MS claims: the EES can itself be seen as a useful flag, 634 although obviously in a completely changed socio--‐political and scientific context. If the 'flag effect' is 635 partly explanatory to the MS, there is no reason why we should not consider it when we think to the 636 EES. A collection of conceptual pillars (Fig. 1) is not necessarily a good description of the status and 637 tranformations of evolutionary biology, whereas apparently it does make an effective flag, an 638 aggregating flag reminiscent of Mayr's ensign. The instabilities and disagreements we have described 639 stand, in part, as symptoms for all these partiality aspects. On the other hand, the MS and the EES 640 certainly represent more than partisan interests: they are pleas for the good of the field. With 641 reference to the MS, Delisle (2011) talked about a "sociological synthesis" – made of transformations 642 in the social configuration of science, exchange among disciplinary communities, institutional bridges 643 – as something separate from conceptual unification that, for him and many others, was never quite 644 achieved. The EES might represent a continuation of the struggle – already present in the MS – 645 against disfunctional imbalance of prestige and resources granted to molecular methods vs. other 646 methods, in an age of cheaper high--‐throughput sequencing that produces rivers of publications.21 647 Other redistributions might be at stake, for example between botanists and microbiologists vs. 648 zoologists, or concerning new means of knowledge such as simulations. The EES could be, today, a 649 flag for many streams of study that have been suffering due to perceived scientific dominant 650 tendencies or fashions, a flag recruited by an ongoing struggle for very basic needs of any scientist: 651 funding, publication, consensus. Let us make some examples. Odling--‐Smee's suggestion of niche 652 construction (1988) waited some ten years to be taken up by a few mainstream modelers and 653 population geneticists (Laland et al. 1996), who, in turn, offered their models to call for a global 654 21 One thing that becomes clear from a reading of the history of the MS is that it sought to present a unified front against the rise and usurpation of molecular biologists. This aspect of the story is quite relevant to understanding what's going on with the EES as evolutionary biologists face up to the fact that many of their tools today are molecular. © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 30 rethinking of evolutionary biology (Laland et al. 2009), and still, it would appear, to date their effort 655 have breached almost exclusively among philosophers and human scientists (e.g., Kendal et al. 2011). 656 Jablonski's work on multilevel processes in macroevolution was part of the paleobiological revolution 657 (Sepkoski and Ruse 2009; Sepkoski 2012) since the 1980s (Jablonski 1986). Macroevolution is today a 658 big and consolidated field, but the most radical implications for evolutionary mechanisms are still 659 unsettled (Serrelli and Gontier forthcoming). Jablonka has been a vocal and harsh critic of the MS for 660 many years (Jablonka and Lamb 1989). On the other hand, the evolutionary importance of 661 epigenetics has been considered negligible due, for example, to the lability of epigenetically 662 transmitted modifications over evolutionary time, and proponents like Jablonka have long been 663 accused from overusing a few experimental cases (e.g., Haig 2007). David S. Wilson (e.g., 2009) 664 describes the scientific battle over group selection spanning 150 years, beginning with Darwin. 665 Wilson himself started a strenuous defense of group selection since 1970s (Wilson 1975; Wilson and 666 Dugatkin 1997; Sober and Wilson 1998). Notwithstanding peer--‐reviewed publications on the subject 667 (Wilson and Wilson 2007; Eldakar and Wilson 2011), a multimedia battle still goes on with 668 personalities such as Dawkins and Coyne that tirelessly deny any possibility of group selection in 669 evolution. Kirschner and Gerhart started to defend evolvability in late 1990s (1998). Opponent, Lynch 670 (e.g., 2007) keeps bringing back evolvability to its population genetics meaning (related to 671 heritability) and defines other versions of evolvability as "speculation, which is almost entirely 672 restricted to molecular and cell biologists and those who study digital organisms" (pp. 8602--‐3). 673 These are some of the various fierce streams of research that have decided to become associated 674 with the EES. Notwithstanding the various reasons of the involved actors, just like the MS had helped 675 the advancement of science, the EES really contains very important questions: biology has indeed 676 been changing, and is changing, around us in many senses; we do want to know how, how fast, how 677 uniformly, what scientists can and should do to second positive movements and contrast negative 678 ones. Answers could, for example, orient economic investment, policy, curriculum planning, 679 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 31 publication choices. But if the EES, like other pictures, is biased by 'flag effects', scientist--‐field 680 disproportion, and all other complexity factors we have reviewed, where will we get those answers? 681 Conclusion: the need of pursuing the promises 682 scientifically 683 I have repeatedly remarked the potential benefit of knowing 'what is it to do research' to plan 684 biology training, choose research lines in a lab, navigate career development, connect specific 685 researches to broader contexts, and make policy decisions on research funding and reward, all in 686 order to make the field advance for the better. These are the high stakes and the promises of 687 encompassing metascientific views, such as the EES, that, at the same time, encounter remarkable 688 difficulties on their way. The EES is a metascientific claim in its being a statement about what's new 689 in how evolutionary biology is carried out, not only a statement about what's new in evolution as we 690 know it. Massimo Pigliucci and Gerd Müller started off, in 2007, with their shared idea that 691 evolutionary biology has been overlooking 'form' in favor of genes and genotypes too long. Thanks to 692 some initiatives they organized, they then expanded and modified their ideas bringing about a list of 693 many mechanisms, measures, fields, perspectives, and applications of evolutionary theory that were 694 not present in the MS. The dynamism of the enlisted concepts might reflect the elusive vitality of 695 current evolutionary research, although this would not apply to the equally dynamic portrait of the 696 MS. At a deeper level lie the inherent, growing difficulties of any metascientific view: the vastness 697 and complexity of any scientific field, the insufficiency of conceptual analysis to capture the thickness 698 of scientific research, the entanglement between empirical and metascientific concepts, between 699 multiple chronologies, and between descriptive and normative needs, as well as the inevitable 700 stakeholding of any reviewer involved in the reviewed field. So how do we get insights about the 701 shifting state of something so broad, fragmented, and lively like evolutionary biology? While 702 databanks of specific research objects (a gene, a species) are flourishing, scientists don't access 703 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 32 meaningful and rigorous data about the scientific community. Yet, let me suggest that helpful 704 methods and notions exist in different disciplines, and perhaps would only need to be applied and 705 integrated to construct a metascientific view of evolutionary biology. 706 What's the real trajectory of the consideration of phenotypes, or of ecology, in the community of 707 evolutionary biologists? What is really happening to evolutionary biology in relation to what many 708 people call 'evo--‐devo', or with what different groups call 'integration of evolution with ecology'? 709 When and how, if ever, evo--‐devo changed the way evolutionary research is carried out in other parts 710 of the field? Is epigenetic inheritance really related to new ways of doing science? Conceptual 711 analysis of theories, beloved by philosophers and by some scientists, must be complemented to 712 achieve accounts that are more grounded and useful to biologists. Real substance of metascientific 713 views are the diffusion of those concepts, the changing role of those concepts in scientific research, 714 and the congruent partitioning and repartitioning of the scientific community relating to various 715 ways of being evolutionary biologists. Several studies already go in this direction. Scheiner (2013) 716 performed some quick quantitative historical analyses of ecology to measure theory--‐engagement in 717 that field. Something similar might be done to assess the integration between evolution and ecology. 718 Love and colleagues (Love 2003, 2006, 2007; Love and Raff 2003; Raff and Love 2004) made 719 interesting attempts to re--‐evaluate the received conviction that development was excluded by the 720 MS. To this aim they mixed historical and conceptual methods: they dissected the different kinds of 721 developmental studies that might have been excluded, looking for clues about possible exclusion of 722 one or more of these 'embryologies'; they searched fields like morphology and paleontology that 723 also were seemingly side--‐lined; they spelled out different kinds of exclusion. But even more can be 724 done. 725 Information sciences have techniques for the automatic retrieval, analysis and representation in 726 corpora of big data. Recent studies have focused on scientific/academic information, its search, 727 recommendation and distribution (McCain et al. 2005, McCain 2008, 2009, Riviera 2013). 728 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 33 Scientometrics, i.e. the quantitative study of science, can reveal relations between units such as 729 authors, disciplines, institutions, semantic elements. Study of patterns in citations, texts, and user 730 behaviors (McCain 2013) through time can trace 'lineages of ideas' and reveal phenomena about the 731 scientific community, such as fields emergence and decline. The ongoing explosion of online journals 732 and digital archives matches perfectly these techniques, although it also demands corrections and 733 creative solutions as the analysis goes back in time – as it will always do, since as we have seen 734 metascientific claims are almost always historical claims. The domain of analysis can also be 735 expanded multilingually to conference programmes and abstracts, research protocols, official 736 documents, and to alternative media that are becoming more important in the economy of scientific 737 work: online tools, institutional websites, science news and blogs. 738 Synthesis, if any, must have scientometric correlates, provided that, although textual search is very 739 powerful, it must be guided by the right queries. At the same time, work in the social sciences 740 demonstrates that understanding scientific communities is broader than bibliometrics. For example, 741 quantities about scientific papers should be related to the (changing) social function of scientific 742 papers (Riviera 2013). White and McCain (1998) affirm that techniques such as 'authors co--‐citation 743 analysis' are "no substitute for extensive reading and fine--‐grained content analysis": "they produce 744 history of the cliometric sort, which leaves out almost all the good parts, [for example] what actually 745 gave rise to the most significant work" (p. 327). The job of biologists has certainly changed, and we 746 want to understand how: laboratory ethnography and biographical research have methods to 747 answer (see Caduff 1999, Hess 2001), and also to bring about reliable indicators to obtain large scale 748 descriptions of evolutionary biology. Some prior, qualitative study of research and writing practice in 749 biology will be necessary in order to extract significant clues, indexes, proxies, and patterns that can 750 feed quantitative research and yield meaningful answers. Ethnographic work must be in turn 751 informed by sound theoretical knowledge and epistemological hypotheses, if it has to provide 752 quantitative analyses with meaningful search keys. Then, if we really want to understand and 753 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 34 explain, it will be necessary to involve knowledge and methods from, e.g., the sociology (Gieryn 754 1983, Bourdieu 1993, Riviera 2013) and the economics (Stephan 1996, 2012, Sent 1999, 2013, Thicke 755 2013) of science, that hold important keys to the reasons for conformism and innovation, stability 756 and change in science. Talking about the MS as a 'constraining theoretical framework' is interesting, 757 but many quarrels on the plausibility of such a constraint arise, probably, from the lack of serious 758 consideration of other really constraining factors: policies, politics, culture, economic investments, 759 technology, reward structure of science, the social role of the evolutionists, the structure of the 760 community, and the like. After all, scientific conformism that EES advocates attribute to the rigid 761 theoretical framework they call the MS might well find appropriate pieces of explanation in the 762 economic and social structure of science over the 20th Century. This is why we also need to ask 763 economics and sociology to describe the social dynamics of evolutionary biology and the conditions 764 and identities of evolutionary biologists over time and across geographical ranges. If these aspects 765 are changing, considering them will be crucial in either the EES or other metatheoretical views we 766 can build. The birth of a field is also the birth of a new way of doing science, as well as a statement of 767 identity, and is described by the changing conditions of the scientific community, not only by the 768 map of involved concepts. What can or cannot be done in a science is constrained and channeled by 769 cultural, social, and economic aspects of science, for example technological advances and costs, or 770 cultural obstacles regarding training, job market and evaluation, grant systems, publication, language 771 barriers (Sidlauskas 2010). Sociology, ethnography, economics and history have tools and knowledge 772 for all these explanatory aspects that, moreover, are essential to any description of a scientific 773 community. 774 Scientific methods can let us observe metascientific change of evolutionary biology and, in face of 775 their variety and heterogeneity, they should be themselves 'synthesized' in some way. The National 776 Center for Evolutionary Synthesis (Sidlauskas et al. 2010) defines 'synthetic science' as an integration 777 © Emanuele Serrelli – The Extended Evolutionary Synthesis – October 2014 draft 35 of different kinds of data from multiple sources. Various kinds of synthetic science, achieved in 778 diverse ways, exist. 779 My humble methodological suggestions are, at this stage, only meant to help the imagination of 780 metascientific views built with a more scientific, interdisciplinary approach. Of course they will still 781 be prone to complex chronologies and description--‐prescription oscillations, but they will certainly be 782 more fecund of guidelines for choices and policies that will favor the growth of our knowledge of 783 evolution more effectively than the familiar flaggish conceptual analyses. Closing the circle, a serious 784 multi--‐disciplinary approach to the evolutionary scientific community could be able to explain the 785 timely appearance of metascientific claims such as the MS and the EES, the useful flags. This would 786 not prevent turning the contents of the MS and of the EES into quantifiable and testable hypotheses, 787 and of course doesn't exclude that scientists like Pigliucci and Müller are interpreting correctly some 788 global synthesis happening around us. What is certain, is that a complete answer to questions like 789 Pigliucci's may only be sought by looking scientifically at the scientific community as such, relating 790 the epistemological, social, and human aspects of what it is to do evolutionary biology over historical 791 time. We will then be able to face Pigliucci's question "Do we need an Extended Evolutionary 792 Synthesis?" on better grounds, whether to answer it or to reformulate it, in either case fulfilling the 793 need for maintenance of evolutionary biology in a more shared and uncontroversial way. 794 Acknowledgements 795 The author thanks Samuel M. Scheiner and two anonymous referees for invaluable support and 796 useful suggestions on the text. Allen Rodrigo, Florence Debarre, Giuseppe Fusco, Alessandro Minelli 797 and Maria Berica Rasotto provided useful conference feedbacks. 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A comparison among publication (either with or without diagrams) uncovers dynamism and 1098 problematic factors of complexity in the development of Pigliucci and Müller's thought. 1099