Evolutionary biology is a field currently animated by much discussion concerning its conceptual foundations. On the one hand, we have supporters of a classical view of evolutionary theory, whose backbone is provided by population genetics and the so-called Modern Synthesis (MS). On the other hand, a number of researchers are calling for an Extended Synthe- sis (ES) that takes seriously both the limitations of the MS (such as its inability to incorporate developmental biology) and recent empirical and theoretical research on (...) issues such as evolvability, modularity, and self-organization. In this article, I engage in an in-depth commentary of an influential paper by population geneticist Michael Lynch, which I take to be the best defense of the MS-population genetics position published so far. I show why I think that Lynch’s arguments are wanting and propose a modification of evolutionary theory that retains but greatly expands on population genetics. (shrink)

There have been periodic claims that evolutionary biology needs urgent reform, and this article tries to account for the volume and persistence of this discontent. It is argued that a few inescapable properties of the field make it prone to criticisms of predictable kinds, whether or not the criticisms have any merit. For example, the variety of living things and the complexity of evolution make it easy to generate data that seem revolutionary, and lead to disappointment with existing explanatory frameworks. (...) It is then argued that special discontent stems from misunderstandings and dislike of one well-known but atypical research programme: the study of adaptive function, in the tradition of behavioural ecology. To achieve its goals, this research needs distinct tools, often including imaginary agency, and a partial description of the evolutionary process. This invites mistaken charges of narrowness and oversimplification, and these chime with anxieties about human agency and overall purpose. The article ends by discussing several ways in which calls to reform evolutionary biology actively hinder progress in the field. (shrink)

Darwinism is defined here as an evolving research tradition based upon the concepts of natural selection acting upon heritable variation articulated via background assumptions about systems dynamics. Darwin’s theory of evolution was developed within a context of the background assumptions of Newtonian systems dynamics. The Modern Evolutionary Synthesis, or neo-Darwinism, successfully joined Darwinian selection and Mendelian genetics by developing population genetics informed by background assumptions of Boltzmannian systems dynamics. Currently the Darwinian Research Tradition is changing as it incorporates new information (...) and ideas from molecular biology, paleontology, developmental biology, and systems ecology. This putative expanded and extended synthesis is most perspicuously deployed using background assumptions from complex systems dynamics. Such attempts seek to not only broaden the range of phenomena encompassed by the Darwinian Research Tradition, such as neutral molecular evolution, punctuated equilibrium, as well as developmental biology, and systems ecology more generally, but to also address issues of the emergence of evolutionary novelties as well as of life itself. (shrink)

On the basis of findings from developmental biology, some researchers have argued that evolutionary theory needs to be significantly updated. Advocates of such a “developmental update” have, among other things, suggested that we need to re-conceptualize units of selection, that we should expand our view of inheritance to include environmental as well as genetic and epigenetic factors, that we should think of organisms and their environment as involved in reciprocal causation, and that we should reevaluate the rates of evolutionary change. (...) However, many of these same conclusions could be reached on the basis of other evidence, namely from microbiology. In this paper, I ask why microbiological evidence has not had a similarly large influence on calls to update biological theory, and argue that there is no principled reason to focus on developmental as opposed to microbiological evidence in support of these revisions to evolutionary theory. I suggest that the focus on developmental biology is more likely attributable to historical accident. I will also discuss some possible room for overlap between developmental and microbiology, despite the historical separation of these two subdisciplines. (shrink)

This paper will critically assess Popper’s evolutionary philosophy. There exists a rich literature on the topic with which we have many reservations. We believe that Popper’s evolutionary philosophy should be assessed in light of the intriguing theoretical insights offered, during the last 10 years or so, by the philosophy of biology, evolutionary biology and molecular biology. We will argue that, when analysed in this manner, Popper’s ideas concerning the nature of selection, Lamarckism and the theoretical limits of neo-Darwinism can be (...) appreciated in their full biological and philosophical value. (shrink)

In this paper, I explore how bio-hybrid forms can be created and combined starting from organic forms. The thesis put forward is epistemological: the combinatorial practice of bionics, biomimetics, biorobotics, and all design strategies inspired by nature is not based on a kind of biomimetic inspiration, i. e., on a kind of imitation of nature, but on a practice of translation. To develop this thesis, I focus on the practices of contemporary biorobotics, first examining the practice of translating natural forms (...) into technical artefacts as developed by Raoul Heinrich Francé at the beginning of the 20th century, secondly, analysing the production of robots capable of replicating complex locomotion systems and, finally, investigating the interaction between robots and living organisms (fish). In the last part of the paper, I reflect on the philosophical payoff and broader conditions of possibility for this translational practice. I discuss when and to what extent a translation of biological forms into biotechnical ones is acceptable and point out the notion of form that underlies this practice. Moreover, I draw attention to the need to philosophically investigate what happens between different domains of knowledge – and especially between science and technology. This article is thus an invitation to philosophers to develop a philosophy in the interstices of knowledge production. (shrink)

Transhumanism has enormous effect on temporary philosophical thought by forcing philosophers to take on many intellectual challenges. Not only philosophers deal with transhumanism but also scientists who try to create technological solutions that enable implementation of transhumanistic ideas. The question is whether all these ideas will be realized. The purpose of the article is to show that not all transhumanist aspirations can be put into practice. The first reason is that transhumanism limits human’s understanding to the material dimension. While this (...) is understandable in the naturalistic paradigm, this approach is insufficient when it comes to all complexity of human being and for this reason tanshumanism represents too narrow a human’s understanding to be able to implement its all assumptions. The second reason is that to enable people to become posthumans the latest technologies would have to be available to everyone and this seems impossible. If so, such a situation will divide people into ordinary people and posthumans and this could lead to conflicts that transhumanists want to avoid after all. Finally, the body-mind problem is essentially limited to emergentism, which corresponds to the naturalistic paradigm. It seems, however, that without the concept of the soul it is impossible to understand who a man is, his/her identity and consciousness and this is crucial for mind uploading. (shrink)

Evolutionary adaptation has been suggested as the hallmark of life that best accounts for life’s creativity. However, current evolutionary approaches still fail to give an adequate account of it, even if they are able to explain both the origin of novelties and the proliferation of certain traits in a population. Although modern-synthesis Darwinism is today usually appraised as too narrow a position to cope with all the complexities of developmental and structural biology—not to say biosemiotic phenomena—, Darwinism need not be (...) if we separate metaphor from reality in natural selection in order to show the axiological complexity of this concept. This can shed light on the relationship between biosemiotics and biological evolution. (shrink)

What kind mechanisms one deems central for the evolutionary process deeply influences one's understanding of the nature of organisms, including cognition. Reversely, adopting a certain approach to the nature of life and cognition and the relationship between them or between the organism and its environment should affect one's view of evolutionary theory. This paper explores this reciprocal relationship in more detail. In particular it argues that the view of living and cognitive systems, especially humans, as deeply integrated beings embedded in (...) and transformed by their genetic, epigenetic, behavioral, ecological, socio-cultural and cognitive-symbolic legacies calls for an extended evolutionary synthesis that goes beyond either a theory of genes juxtaposed against a theory of cultural evolution and or even more sophisticated theories of gene-culture coevolution and niche construction. Environments, particularly in the form of developmental environments, do not just select for variation, they also create new variation by influencing development through the reliable transmission of non-genetic but heritable information. This paper stresses particularly views of embodied, embedded, enacted and extended cognition, and their relationship to those aspects of extended inheritance that lie between genetic and cultural inheritance, the still gray area of epigenetic and behavioral inheritance systems that play a role in parental effect. These are the processes that can be regarded as transgenerational developmental plasticity and that I think can most fruitfully contribute to, and be investigated by, developmental psychology. (shrink)

Current Perspectives in Philosophy of Biology.

Roger Sansom and Robert N. Brandon (eds.): Integrating Evolution and Development: From Theory to Practice Content Type Journal Article Pages 81-86 DOI 10.1007/s10441-010-9121-x Authors Thomas A. C. Reydon, Institute of Philosophy & Center for Philosophy and Ethics of Science (ZEWW), Leibniz Universität Hannover, Im Moore 21, 30167 Hannover, Germany Journal Acta Biotheoretica Online ISSN 1572-8358 Print ISSN 0001-5342 Journal Volume Volume 59 Journal Issue Volume 59, Number 1.

Sewall Wright introduced the metaphor of evolution on “adaptive landscapes” in a pair of papers published in 1931 and 1932. The metaphor has been one of the most influential in modern evolutionary biology, although recent theoretical advancements show that it is deeply flawed and may have actually created research questions that are not, in fact, fecund. In this paper I examine in detail what Wright actually said in the 1932 paper, as well as what he thought of the matter at (...) the very end of his career, in 1988. While the metaphor is flawed, some of the problems which Wright was attempting to address are still with us today, and are in the process of being reformulated as part of a forthcoming Extended Evolutionary Synthesis. (shrink)

We argue that the economy of nature constitutes an invocation of structure in the biological sciences, one largely missed by philosophers of biology despite the turn in recent years toward structural explanations throughout the philosophy of science. We trace a portion of the history of this concept, beginning with the theologically and economically grounded work of Linnaeus, moving through Darwin’s adaptation of the economy of nature and its reconstitution in genetic terms during the first decades of the Modern Synthesis. What (...) this historical case study reveals, we argue, is a window into the shifting landscape of the explanatory and ontic uses of structural concepts. In Linnaeus, the economy of nature has both ontic and explanatory import; in Darwin the ontic and explanatory aspects start to come apart ; and finally, in the Modern Synthesis, the economy of nature is replaced by the conceptual toolkit of population genetics, the structural elements of which are nearly entirely explanatory. Having traced a historical trajectory of structural concepts that moves from an ontic formulation to an increasingly explanatory one, we conclude by outlining some insights for structural realism. (shrink)

Ernst Mayr’s classical work on the nature of causation in biology has had a huge influence on biologists as well as philosophers. Although his distinction between proximate and ultimate causation recently came under criticism from those who emphasize the role of development in evolutionary processes, the formal relationship between these two notions remains elusive. Using causal graph theory, this paper offers a unified framework to systematically translate a given “proximate” causal structure into an “ultimate” evolutionary response, and illustrates evolutionary implications (...) of various kinds of causal mechanisms including epigenetic inheritance, maternal effects, and niche construction. These results not only reveal the essential interplay between proximate and ultimate causation in the study of evolution, but also provide a formal method to evaluate or discover non-standard or yet unknown evolutionary phenomena. (shrink)

The Modern Synthesis (MS) gene-centered population model of evolution is currently being challenged by the Extended Evolutionary Synthesis (ESS) organism-centered developmental model of evolution. The predictions of the EES are here examined with respect to the arguments of Edward Drinker Cope (1840–1897) for an organism-centered evolutionary process in which organisms both shape and are shaped by their environments such that the activities of the organisms themselves play a role in their own evolution.

Reichenbach’s early solution to the scientific problem of how abstract mathematical representations can successfully express real phenomena is rooted in his view of coordination. In this paper, I claim that a Reichenbach-inspired, ‘layered’ view of coordination provides us with an effective tool to systematically analyse some epistemic and conceptual intricacies resulting from a widespread theorising strategy in evolutionary biology, recently discussed by Okasha (2018) as ‘endogenization’. First, I argue that endogenization is a form of extension of natural selection theory that (...) comprises three stages: quasi-axiomatisation, functional extension, and semantic extension. Then, I argue that the functional extension of one core principle of natural selection theory, namely, the principle of heritability, requires the semantic extension of the concept of inheritance. This is because the semantic extension of ‘inheritance’ is necessary to establish a novel form of coordination between the principle of heritability and the extended domain of phenomena that it is supposed to represent. Finally, I suggest that – despite the current lack of consensus on the right semantic extension of ‘inheritance’ – we can fruitfully understand the reconceptualization of ‘inheritance’ provided by niche construction theorists as the result of a novel form of coordination. (shrink)

Evolutionary developmental biology (Evo-devo) is a vibrant area of contemporary life science that should be (and is) increasingly incorporated into teaching curricula. Although the inclusion of this content is important for biological pedagogy at multiple levels of instruction, there are also philosophical lessons that can be drawn from the scientific practices found in Evo-devo. One feature of particular significance is the interdisciplinary nature of Evo-devo investigations and their resulting explanations. Instead of a single disciplinary approach being the most explanatory or (...) fundamental, different methodologies from biological disciplines must be synthesized to generate empirically adequate explanations. Thus, Evo-devo points toward a non-reductionist epistemology in biology. I review three areas where these synthetic efforts become manifest as a result of Evo-devo’s practices (form versus function reasoning styles; problem-structured investigations; idealizations related to studying model organisms), and then sketch some possible applications to teaching biology. These philosophical considerations provide resources for life science educators to address (and challenge) key aspects of the National Science Education Standards and Benchmarks for Scientific Literacy. (shrink)

Using the context of controversies surrounding evolutionary developmental biology (EvoDevo) and the possibility of an Extended Evolutionary Synthesis, I provide an account of theory structure as idealized theory presentations that are always incomplete (partial) and shaped by their conceptual content (material rather than formal organization). These two characteristics are salient because the goals that organize and regulate scientific practice, including the activity of using a theory, are heterogeneous. This means that the same theory can be structured differently, in part because (...) theory presentations (as idealizations) intentionally depart from different features known to be present in a theory. Since there are diverse and potentially incompatible theory structures derived from heterogeneous goals found in scientific practices, a question arises about the absence of a unifying theory structure in the background. The notion of a “theory façade” offers a fruitful perspective on this potentially unsettling result. (shrink)

Adaptation by means of natural selection depends on the ability of populations to maintain variation in heritable traits. According to the Modern Synthesis this variation is sustained by mutations and genetic drift. Epigenetics, evodevo, niche construction and cultural factors have more recently been shown to contribute to heritable variation, however, leading an increasing number of biologists to call for an extended view of speciation and evolution. An additional common feature across the animal kingdom is learning, defined as the ability to (...) change behavior according to novel experiences or skills. Learning constitutes an additional source for phenotypic variation, and change in behavior may induce long lasting shifts in fitness, and hence favor evolutionary novelties. Based on published studies, I demonstrate how learning about food, mate choice and habitats has contributed substantially to speciation in the canonical story of Darwin’s finches on the Galapagos Islands. Learning cannot be reduced to genetics, because it demands decisions, which requires a subject. Evolutionary novelties may hence emerge both from shifts in allelic frequencies and from shifts in learned, subject driven behavior. The existence of two principally different sources of variation also prevents the Modern Synthesis from self-referring explanations. (shrink)

In this article I will analyze whether the so-called Extended Evolutionary Synthesis represents a synthesis and an extension with respect to its predecessor, Modern Synthesis. It will be argued that the MS proposes an externalist approach to evolution while the EES considers it necessary to overcome the internalism/externalism dichotomy by proposing more integrative approaches. It will be concluded that the EES cannot be considered an extension of MS and that the appeal to that extension is related to sociological aspects and (...) the epistemic value of theoretical unification that was always present in biological evolutionary thinking. (shrink)

Microscopy has revealed tremendous diversity of bacterial and eukaryotic forms. Recent molecular analyses show discordance in estimates of biodiversity between morphological and molecular analyses. Moreover, phylogenetic analyses of the diversity of microbial forms reveal evidence of convergence at scales as deep as interdomain: morphologies shared between bacteria and eukaryotes. Here, we highlight examples of such discordance, focusing on exemplary lineages such as testate amoebae, ciliates, and cyanobacteria. These have long histories of morphological study, enabling deeper analyses on both the molecular (...) and morphological sides. We discuss examples in two main categories: (i) morphologically identical (or highly similar) individuals that are genetically distinct and (ii) morphologically distinct individuals that are genetically the same. We argue that hypotheses about discordance can be tested using the concept of neutral morphologies, or more broadly neutral phenotypes, as a null hypothesis. -/- . (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)

In a recent opinion piece, Denis Duboule has claimed that the increasing shift towards systems biology is driving evolutionary and developmental biology apart, and that a true reunification of these two disciplines within the framework of evolutionary developmental biology may easily take another 100 years. He identifies methodological, epistemological, and social differences as causes for this supposed separation. Our article provides a contrasting view. We argue that Duboule’s prediction is based on a one-sided understanding of systems biology as a science (...) that is only interested in functional, not evolutionary, aspects of biological processes. Instead, we propose a research program for an evolutionary systems biology, which is based on local exploration of the configuration space in evolving developmental systems. We call this approach—which is based on reverse engineering, simulation, and mathematical analysis—the natural history of configuration space. We discuss a number of illustrative examples that demonstrate the past success of local exploration, as opposed to global mapping, in different biological contexts. We argue that this pragmatic mode of inquiry can be extended and applied to the mathematical analysis of the developmental repertoire and evolutionary potential of evolving developmental mechanisms and that evolutionary systems biology so conceived provides a pragmatic epistemological framework for the EvoDevo synthesis. (shrink)

The presence of various mechanisms of non-genetic inheritance is one of the main problems for current evolutionary theory according to several critics. Sufficient empirical and conceptual reasons exist to take this claim seriously, but there is little consensus on the implications of multiple inheritance systems for evolutionary processes. Here we use the Price Equation as a starting point for a discussion of the differences between four recently proposed categories of inheritance systems; genetic, epigenetic, behavioral and symbolic. Specifically, we address how (...) the components of the Price Equation encompass different non-genetic systems of inheritance in an attempt to clarify how the different systems are conceptually related. We conclude that the four classes of inheritance systems do not form distinct clusters with respect to their effect on the rate and direction of phenotypic change from one generation to the next in the absence or presence of selection. Instead, our analyses suggest that different inheritance systems can share features that are conceptually very similar, but that their implications for adaptive evolution nevertheless differ substantially as a result of differences in their ability to couple selection and inheritance. (shrink)

Universal Darwinism provides a methodology to study the evolution of anatomical form and sociocultural behavior that centers on defining the units and levels of selection, and it identifies the conditions whereby natural selection operates. In previous work, I have examined how this selection-focused evolutionary epistemology may be universalized to include theories that associate with an extended synthesis. Applied evolutionary epistemology is a metatheoretical framework that understands any and all kinds of evolution as phenomena where units evolve by mechanisms at levels (...) of an ontological hierarchy; and it provides three heuristics to search for these units, levels and mechanisms. The heuristics are applicable to language and sociocultural evolution, and here, we give an in-depth analysis of how the unit-heuristic can be implemented into language origin and evolution studies. The importance of developing hierarchy theories is also more fully explained. (shrink)

In this paper, we analyze the debate between the Modern Synthesis and the Extended Evolutionary Synthesis in light of the concept of incommensurability developed by Thomas Kuhn. In order to do so, first we briefly present both the Modern Synthesis and the Extended Evolutionary Synthesis. Then, we clarify the meaning and interpretations of incommensurability throughout Kuhn’s works, concluding that the version of this concept deployed in The Structure of Scientific Revolutions is the best suited to the analysis of scientific disputes. (...) After discussing incommensurability in Kuhn’s works, we address the question of whether the Modern Synthesis and the Extended Evolutionary Synthesis can be considered semantically, methodologically, and ontologically incommensurable, concluding that they can. Finally, we discuss three problems that arise from such a conclusion: firstly, what are the consequences of incommensurability; secondly, which mode of scientific change better explains this current dispute in evolutionary biology; and thirdly, whether rational theory comparison is possible given incommensurability. We suggest that the main consequence of incommensurability is profound disagreement, that the kind of scientific change that better explains the current dispute between the MS and the EES may be scientific specialization, and that incommensurability does not preclude rational theory comparison. (shrink)

The question of whether the modern evolutionary synthesis requires an extension has recently become a topic of discussion, and a source of controversy. We suggest that this debate is, for the most part, not about the modern synthesis at all. Rather, it is about the extent to which genetic mechanisms can be regarded as the primary determinants of phenotypic characters. The modern synthesis has been associated with the idea that phenotypes are the result of gene products, while supporters of the (...) extended synthesis have suggested that environmental factors, along with processes such as epigenetic inheritance, and niche construction play an important role in character formation. We argue that the methodology of the modern evolutionary synthesis has been enormously successful, but does not provide an accurate characterization of the origin of phenotypes. For its part, the extended synthesis has yet to be transformed into a testable theory, and accordingly, has yielded few results. We conclude by suggesting that the origin of phenotypes can only be understood by integrating findings from all levels of the organismal hierarchy. In most cases, parts and processes from a single level fail to accurately explain the presence of a given phenotypic trait. The debate between the proponents of the modern and extended syntheses is somewhat reminiscent of the duck-rabbit illusion. The two sides are probably talking about the same thing, but from different perspectives. If not, then we argue that the challenge is to do an experiment that rules out the alternative view. (shrink)

The Modern Synthesis has received criticism for its purported gene-centrism. That criticism relies on a concept of the gene as a unit of instructional information. In this paper I discuss information concepts and endorse one, developed from Floridi, that sees information as a functional relationship between data and context. I use this concept to inspect developmental criticisms of the Modern Synthesis and argue that the instructional gene arose as an idealization practice when evolutionary biologists made comment on development. However, a (...) closer inspection of key claims shows that at least some associated with the Modern Synthesis were in fact adopting the data led definition I favour and made clear arguments for the role of developmental processes beyond genetic input. There was no instructional gene. (shrink)

Conceptions of adaptation have varied in the history of genetic Darwinism depending on whether what is taken to be focal is the process of adaptation, adapted states of populations, or discrete adaptations in individual organisms. I argue that Theodosius Dobzhansky’s view of adaptation as a dynamical process contrasts with so-called “adaptationist” views of natural selection figured as “design-without-a-designer” of relatively discrete, enumerable adaptations. Correlated with these respectively process and product oriented approaches to adaptive natural selection are divergent pictures of organisms (...) themselves as developmental wholes or as “bundles” of adaptations. While even process versions of genetical Darwinism are insufficiently sensitive to the fact much of the variation on which adaptive selection works consists of changes in the timing, rate, or location of ontogenetic events, I argue that articulations of the Modern Synthesis influenced by Dobzhansky are more easily reconciled with the recent shift to evolutionary developmentalism than are versions that make discrete adaptations central. (shrink)

In recent years, several prominent biologists have pointed to the relatively new field of evolutionary developmental biology (EvoDevo) as evidence of an Extended Synthesis in evolutionary biology. More particularly, these biologists claim that theoretical and empirical EvoDevo research is extending the Modern Synthesis framework of evolutionary theory through investigation of evolutionarily important concepts that are not part of the framework developed during the 20th century. To describe the current changes in evolutionary biology as an Extended Synthesis, however, is incorrect. Through (...) review of Extended Synthesis arguments and analysis of the same biological concepts used to support these arguments, I argue that the foundation of the Modern Synthesis framework, theoretical population genetics, faces significant, perhaps insurmountable challenges from the concepts highlighted by EvoDevo research. As the foundation of the Modern Synthesis framework will require considerable remodeling—if possible—in light of the concepts emphasized by EvoDevo, it is incorrect to describe the ongoing changes in evolutionary biology as an Extended Synthesis. (shrink)

In recent years, several prominent biologists have pointed to the relatively new field of evolutionary developmental biology as evidence of an Extended Synthesis in evolutionary biology. More particularly, these biologists claim that theoretical and empirical EvoDevo research is extending the Modern Synthesis framework of evolutionary theory through investigation of evolutionarily important concepts that are not part of the framework developed during the 20th century. To describe the current changes in evolutionary biology as an Extended Synthesis, however, is incorrect. Through review (...) of Extended Synthesis arguments and analysis of the same biological concepts used to support these arguments, I argue that the foundation of the Modern Synthesis framework, theoretical population genetics, faces significant, perhaps insurmountable challenges from the concepts highlighted by EvoDevo research. As the foundation of the Modern Synthesis framework will require considerable remodeling—if possible—in light of the concepts emphasized by EvoDevo, it is incorrect to describe the ongoing changes in evolutionary biology as an Extended Synthesis. (shrink)

The relatively new field of evolutionary developmental biology continues to attract considerable attention from biologists, philosophers, and historians, in part, because work in this field demonstrates that important changes are underway within biology. Though studies of development and evolution were closely connected during the 19th century, continued work in genetics fostered a general split between the two during the first decades of the twentieth century (e.g., Allen 1978; Gilbert 1978; Mayr and Provine 1980; Gilbert, Opitz and..

Is one of the roles of theory in biology answering the question “What is life?” This is true of theory in many other fields of science. So why should not it be the case for biology? Yet efforts to identify unifying concepts and principles of life have been disappointing, leading some (pluralists) to conclude that life is not a natural kind. In this essay I argue that such judgments are premature. Life as we know it on Earth today represents a (...) single example and moreover there is positive evidence that it may be unrepresentative of life considered generally. Furthermore, as I discuss, the prototype for theorizing about life has traditionally been based on multicellular plants and animals. Yet biologists have discovered that the latter represent a rare, exotic, and fairly recent form of Earth life. By far the oldest, toughest, most extensive, and diverse form of life on our planet is unicellular, prokaryotic microbes, and there are reasons to suppose that this is almost certainly true elsewhere in the universe as well. If there are explanatorily and predictively powerful, biologically distinctive principles for life that can be gleaned from our insular example of life it is more likely that they will be found among the microbes. I discuss some provocative ways in which unicellular microbes differ from multicellular eukaryotes and argue that some of them just might provide us with key insights into the nature of life. (shrink)

Kevin Laland and colleagues have put forward a number of arguments motivating an extended evolutionary synthesis. Here I examine Laland et al.'s central concept of reciprocal causation. Reciprocal causation features in many arguments supporting an expanded evolutionary framework, yet few of these arguments are clearly delineated. Here I clarify the concept and make explicit three arguments in which it features. I identify where skeptics can—and are—pushing back against these arguments, and highlight what I see as the empirical, explanatory, and methodological (...) issues at stake. (shrink)