Advocates of an ‘extended evolutionary synthesis’ have claimed that standard evolutionary theory fails to accommodate epigenetic inheritance. The opponents of the extended synthesis argue that the evidence for epigenetic inheritance causing adaptive evolution in nature is insufficient. We suggest that the ambiguity surrounding the conception of the gene represents a background semantic issue in the debate. Starting from Haig’s gene-selectionist framework and Griffiths and Neumann-Held’s notion of the evolutionary gene, we define senses of ‘gene’, ‘environment’, and ‘phenotype’ in a way (...) that makes them consistent with gene-centric evolutionary theory. We argue that the evolutionary gene, when being materialized, need not be restricted to nucleic acids but can encompass other heritable units such as epialleles. If the evolutionary gene is understood more broadly, and the notions of environment and phenotype are defined accordingly, current evolutionary theory does not require a major conceptual change in order to incorporate the mechanisms of epigenetic inheritance. _1_ Introduction _2_ The Gene-centric Evolutionary Theory and the ‘Evolutionary Gene’ _2.1_ The evolutionary gene _2.2_ Genes, phenotypes, and environments _3_ Epigenetic Inheritance and the Gene-Centred Framework _3.1_ Treating the gene as the sole heritable material? _3.2_ Epigenetics and phenotypic plasticity _4_ Conclusion. (shrink)

Advocates of an ‘extended evolutionary synthesis’ have claimed that standard evolutionary theory fails to accommodate epigenetic inheritance. The opponents of the extended synthesis argue that the evidence for epigenetic inheritance causing adaptive evolution in nature is insufficient. We suggest that the ambiguity surrounding the conception of the gene represents a background semantic issue in the debate. Starting from Haig’s gene-selectionist framework and Griffiths and Neumann-Held’s notion of the evolutionary gene, we define senses of ‘gene’, ‘environment’, and ‘phenotype’ in a way (...) that makes them consistent with gene-centric evolutionary theory. We argue that the evolutionary gene, when being materialized, need not be restricted to nucleic acids but can encompass other heritable units such as epialleles. If the evolutionary gene is understood more broadly, and the notions of environment and phenotype are defined accordingly, current evolutionary theory does not require a major conceptual change in order to incorporate the mechanisms of epigenetic inheritance. 1 Introduction 2 The Gene-centric Evolutionary Theory and the ‘Evolutionary Gene’ 2.1 The evolutionary gene 2.2 Genes, phenotypes, and environments 3 Epigenetic Inheritance and the Gene-Centred Framework 3.1 Treating the gene as the sole heritable material? 3.2 Epigenetics and phenotypic plasticity 4 Conclusion. (shrink)

Recent work on inheritance systems can be divided into inclusive conceptions, according to which genetic and non-genetic inheritance are both involved in the development and transmission of nearly all animal behavioral traits, and more demanding conceptions of what it takes for non-genetic resources involved in development to qualify as a distinct inheritance system. It might be thought that, if a more stringent conception is adopted, homologies could not subsist across two distinct inheritance systems. Indeed, it is commonly assumed that homology (...) relations cannot survive a shift between genetic and cultural inheritance systems, and substantial reliance has been placed on that assumption in debates over the phylogenetic origins of hominin behavioral traits, such as male-initiated intergroup aggression. However, in the homology literature it is widely accepted that a trait can be homologous—that is, inherited continuously in two different lineages from a single common ancestor—despite divergence in the mechanisms involved in the trait’s development in the two lineages. In this paper, we argue that even on an extremely stringent understanding of what it takes for developmental resources to form a separate inheritance system, homologies can nonetheless subsist across shifts between distinct inheritance systems. We argue that this result is a merit of this way of characterizing what it is to be an inheritance system, that it has implications for adjudicating between alternative accounts of homology, and that it offers an important cautionary lesson about how to reason with the homology concept, particularly in the context of cultural species. (shrink)

The concept of adaptation is employed in many fields such as biology, psychology, cognitive sciences, robotics, social sciences, even literacy and art,1 and its meaning varies quite evidently according to the particular research context in which it is applied. We expect to find a particularly rich catalogue of meanings within evolutionary biology, where adaptation has held a particularly central role since Darwin’s The Origin of Species (1859) throughout important epistemological shifts and scientific findings that enriched and diversified the concept. Accordingly, (...) a conceptual taxonomy of adaptation in evolutionary biology may help to disambiguate it. Interdisciplinary researches focused on adaptation would benefit from such a result. In the present work we recognize and define seven different meanings of adaptation: (1) individual fitness; (2) adaptation of a population; (3) adaptation as the process of natural selection; (4) adaptive traits; (5) molecular adaptation; (6) adaptation as structural tinkering; (7) plasticity. For convenience here, we refer to them as W-, P-, NS-, T-, M-, S- and PL-ADAPTATION. We present the seven meanings in some detail, hinting at their respective origins and conceptual developments in the history of evolutionary thought (references are offered for further deepening). However, it is important to point out that evolution researchers seldom if ever refer to a single meaning purified from the others. This applies also to the authors we cite as representatives of one of the seven meanings. In Discussion and Conclusion draw from our work some future perspectives for adaptation within evolutionary biology. (shrink)

Evolutionary developmental biology is a rapidly growing discipline whose ambition is to address questions that are of relevance to both evolutionary biology and developmental biology. This field has been increasingly progressing as a new and independent comparative science. However, we argue that evo-devo’s comparative approach is challenged by several metaphysical, methodological and socio-disciplinary issues related to the foundation of heuristic functions of model organisms and the possible criteria to be adopted for their selection. In addition, new tools have to be (...) developed to deal with newly chosen model organisms. Therefore, we present a modelling framework suitable to integrate data on individual variation into evo-devo studies on new model organisms and thus to compensate for current idealization practices deliberately suppressing variation. (shrink)

Although classical evolutionary theory, i.e., population genetics and the Modern Synthesis, was already implicitly ‘gene-centred’, the organism was, in practice, still generally regarded as the individual unit of which a population is composed. The gene-centred approach to evolution only reached a logical conclusion with the advent of the gene-selectionist or gene’s eye view in the 1960s and 1970s. Whereas classical evolutionary theory can only work with fitness differences between individual organisms, gene-selectionism is capable of working with fitness differences among genes (...) within the same organism and genome. Here, we explore the explanatory potential of ‘intra-organismic’ and ‘intra-genomic’ gene-selectionism, i.e., of a behavioural-ecological ‘gene’s eye view’ on genetic, genomic and organismal evolution. First, we give a general outline of the framework and how it complements the—to some extent—still ‘organism-centred’ approach of classical evolutionary theory. Secondly, we give a more in-depth assessment of its explanatory potential for biological evolution, i.e., for Darwin’s ‘common descent with modification’ or, more specifically, for ‘historical continuity or homology with modular evolutionary change’ as it has been studied by evolutionary developmental biology during the last few decades. In contrast with classical evolutionary theory, evo-devo focuses on ‘within-organism’ developmental processes. Given the capacity of gene-selectionism to adopt an intra-organismal gene’s eye view, we outline the relevance of the latter model for evo-devo. Overall, we aim for the conceptual integration between the gene’s eye view on the one hand, and more organism-centred evolutionary models on the other. (shrink)

I identify a controversial hypothesis in evolutionary biology called the plasticity-first hypothesis. I argue that the plasticity-first hypothesis is underdetermined and that the most popular means of studying the plasticity-first hypothesis are insufficient to confirm or disconfirm it. I offer a strategy for overcoming this problem. Researchers need to develop a richer middle range theory of plasticity-first evolution that allows them to identify distinctive empirical traces of the hypothesis. They can then use those traces to discriminate between rival explanations of (...) evolutionary episodes. The best tools for developing such a middle range theory are experimental evolution and formal modelling. (shrink)

Four sequential, sub-processes are identified as the fundamental steps in the processing of signals by big-brained animals. These are, Detection of the signal, its Representation in correlated sensory brain structure, the Interpretation of the signal in another part of the brain and the Expression of the receiver’s response. We label this four-step spatiotemporal process DRIE. We support the view that when the context within which such signals are produced and received is relatively constant, the DRIE process can be ultimately assimilated (...) into the genome, with the Interpretation sub-phase is markedly decreased in duration as speed and efficiency are maximized. With frequent repetition and learning, an analogous result can be attained epigenetically as exemplified in human word and text recognition, allowing tasks critical to primate social function to be accomplished with rapidity and accuracy. (shrink)