An increasing number of biologists are expressing discontent with the prevailing theory of neo-Darwinism. In particular, the tendency of neo-Darwinians to adopt genetic determinism and atomistic notions of both genes and organisms is seen as grossly unfair to the body of developmental theory. One faction of dissenteers, the Process Structuralists, take their inspiration from the rational morphologists who preceded Darwin. These neo-rationalists argue that a mature biology must possess universal laws and that these generative laws should be sought within organismal (...) development. Such a rational biology will only be possible once the neo-Darwinian paradigm, with its reliance on inherently stochastic processes, is overthrown.To facilitate this revolution, process structuralism launches a broad attack on the theoritical adequacy of its opponent. It is charged that neo-Darwinism is untestable and therefore its hypotheses are nothing more than adaptive stories. Further, the lamentable tendencies toward genetic determinism and atomism by modern biologists is seen as the inescapable consequences of adopting the neo-Darwinian outlook. (shrink)

From the 1930s through the 1970s, C. H. Waddington attempted to reunite genetics, embryology, and evolution. One of the means to effect this synthesis was his model of the epigenetic landscape. This image originally recast genetic data in terms of embryological diagrams and was used to show the identity of genes and inducers and to suggest the similarities between embryological and genetic approaches to development. Later, the image became more complex and integrated gene activity and mutations. These revised epigenetic landscapes (...) presented an image of how mutations could alter developmental pathways to yield larger phenotypic changes. These diagrams became less important as the operon became used to model differential gene regulation. (shrink)

I begin by examining how genetics drivesschizophrenia research, and raise both familiar andrelatively novel criticisms of the evidence putativelysupporting the genetic basis of schizophrenia. Inparticular, I call attention to a set of concernsabout the effects of placentation on concordance ratesof schizophrenia in monozygotic twins, which furtherweakens the case for schizophrenia''s so-called stronggenetic component. I then underscore two criticalpoints. First, I emphasize the importance of takingseriously considerations about the complexity of bothontogenesis and the development of hereditarydiseases. The recognition of developmentalconstraints and (...) supports is crucial, for attention todevelopment exposes the naivete of too many models ofgene action in the aetiology of disease. Secondly, Iattend to those schizophreniologists who ignoremethodological criticisms and thus presume a geneticbasis for schizophrenia, and then seek the schizophrenic genotype lacking an adequatephenotype. In response I attempt to demonstrate thenecessity of a sustained effort at characterizing thephenotype of schizophrenia as an enabling conditionfor the whole enterprise of psychiatric genetics – andfor psychiatry itself. Without the organism-levelphenotype, research at the level of genes will remainunproductive – assuming of course that research at thegenetic level is appropriate at all. (shrink)

This paper examines a new challenge to neo-Darwinism, a movement known as process structuralism. The process structuralist critique of neo-Darwinism holds 1) that there are general laws in biology and that biologists should search for these laws; 2) that there are general forms of morphology and development and that biologists should attempt to uncover these forms; 3) that organisms are unified wholes that cannot be understood without adopting a holistic perspective; and 4) that no special, causal primacy should be given (...) to the genes in development and morphology. This paper places process structuralism in its historical context, examines the philosophical underpinnings of the movement, and discusses some of the evidence used to support its claims. (shrink)

D’Arcy Thompson’s drawings showing coordinated differences between the shape of an individual of one species and the shape of an individual of another have been reproduced and discussed countless times. However, while they have been widely regarded as inspirational, their interpretation in causal terms has proved difficult, and there is as yet no consensus on this matter. Here, I approach these Thompsonian transformations from a particular angle, namely their dimensional insufficiency. I argue that this problem must be solved before the (...) issue of causality can be considered. This approach leads to the conclusion that Thompsonian transformations—or “morphological transformations”—have not taken place in evolution, and logically can never do so, because they involve the direct conversion of the adult form of one species into that of another. In contrast, “developmental transformations” do occur in the short term, within the lifetime of a single individual. And “evolutionary transformations” occur in the long term, in a context that can be described, following Scott Gilbert, as five-dimensional. I argue that these two kinds of transformation—developmental and evolutionary—have different causal agencies. I consider the possible nature of these agencies and, related to that, the way in which Thompson’s work connects with Darwinian evolutionary theory. (shrink)

Determinism and unpredictability are compatible since deterministic flows can produce, if sensitive to initial conditions, unpredictable behaviors. Within this perspective, the notion of scenario to chaos transition offers a new form of predictability for the behavior of sensitive to initial condition systems under the variation of a control parameter. In this paper I first shed light on the genesis of this notion, based on a dynamical systems approach and on considerations of structural stability. I then suggest a link to the (...) figure of epigenetic landscape, partially inspired by a dynamical systems perspective, and offering a theoretical framework to apprehend developmental noise. (shrink)

Processes produce changes: rivers erode their banks and thunderstorms cause floods. If I am right that organisms are a kind of process, then the causally efficacious behaviours of organisms are also examples of processes producing change. In this paper I shall try to articulate a view of how we should think of causation within a broadly processual ontology of the living world. Specifically, I shall argue that causation, at least in a central class of cases, is the interaction of processes, (...) that such causation is the exercise of a capacity inherent in that process and, negatively, that causation should not be understood as the instantiation of universal laws. The approach I describe has substantial similarities with the process causality articulated by Wesley Salmon and Phil Dowe for physical causation, making it plausible that the basic approach can be applied equally to the non-living world. It is an approach that builds at crucial points on the criticisms of determinism and universal causality famously articulated by Elizabeth Anscombe. (shrink)

Biological mimicry is regarded by many as a textbook illustration of Darwin’s idea of evolution by random mutation followed by differential selection of reproductively fit specimens, resulting in gradual phenotypic change in a population. In this paper, I argue that some cases of so-called mimicry are probably merely look-a-likes and do not gain an advantage due to their similarity in appearance to something else. In cases where a similar appearance does provide a benefit, I argue that it is possible that (...) these forms of mimicry were created in a single generation. An interpretive response to an appearance as a sign can make a new structure perform drastically differently in an environment. In such cases, Darwin’s natural selection mechanism only helps to explain gradual the spread of these new forms, not the creation of them. I argue that biosemiosis should be regarded as a much more powerful mechanism for affecting evolutionary trajectories than the gradualist view allows. I focus on two cases of butterfly mimicry: the Viceroy (Nymphalidae: Limenitis archippus) and Monarch (Nymphalidae: Danaus plexippus) butterflies, supposed Müllerian mimics, and deadleaf mimic butterflies (Kallima). (shrink)

A crucial question for a process view of life is how to identify a process and how to follow it through time. The genidentity view can contribute decisively to this project. It says that the identity through time of an entity X is given by a well-identified series of continuous states of affairs. Genidentity helps address the problem of diachronic identity in the living world. This chapter describes the centrality of the concept of genidentity for David Hull and proposes an (...) extension of Hull’s view to the ubiquitous phenomenon of symbiosis. Finally, using immunology as a key example, it shows that the genidentity view suggests that the main interest of a process approach is epistemological rather than ontological and that its principal claim is one of priority, namely that processes precede and define things, and not vice versa. (shrink)

We describe an approach to measuring biological information where ‘information’ is understood in the sense found in Francis Crick’s foundational contributions to molecular biology. Genes contain information in this sense, but so do epigenetic factors, as many biologists have recognized. The term ‘epigenetic’ is ambiguous, and we introduce a distinction between epigenetic and exogenetic inheritance to clarify one aspect of this ambiguity. These three heredity systems play complementary roles in supplying information for development. -/- We then consider the evolutionary significance (...) of the three inheritance systems. Whilst the genetic inheritance system was the key innovation in the evolution of heredity, in modern organisms the three systems each play important and complementary roles in heredity and evolution. -/- Our focus in the earlier part of the paper is on ‘proximate biology’, where information is a substantial causal factor that causes organisms to develop and causes offspring to resemble their parents. But much philosophical work has focused on information in ‘ultimate biology’. Ultimate information is a way of talking about the evolutionary design of the mechanisms of development and inheritance. We conclude by clarifying the relationship between the two. Ultimate information is not a causal factor that acts in development or heredity, but it can help to explain the evolution of proximate information, which is. (shrink)

This paper focuses on a running dispute between Werner Callebaut’s naturalistic view and Filip Kolen and Gertrudis Van de Vijver’s transcendentalist view on the nature of philosophy of biology and the relation of this discipline to biological sciences. It is argued that, despite differences in opinion, both positions agree that philosophy of biology’s ultimate goal is to ‘move’ biology or at least be ‘meaningful’ to it. In order to make this goal clear and effective, more is needed than a polarizing (...) debate which hardly touches upon biology. Therefore, a redirection in discussion is suggested towards a reflection on the possibilities of incorporating philosophy in interdisciplinary research, and on finding concrete research questions which are of interest both to the philosopher and to the biologist. (shrink)

Developmental biology is a theory of interpretation. Developmental signals are interpreted differently depending on the previous history of the responding cell. Thus, there is a context for the reception of a signal. While this conclusion is obvious during metamorphosis, when a single hormone instructs some cells to proliferate, some cells to differentiate, and other cells to die, it is commonplace during normal development. Paracrine factors such as BMP4 can induce apoptosis, proliferation, or differentiation depending upon the history of the responding (...) cells. In addition, organisms have evolved to alter their development in response to differences in temperature, diet, the presence of predators, or the presence of competitors. This allows them to develop the phenotype, within the limits imposed by the genotype, best suited for the immediate habitat of the organism. Most developing organisms have also evolved to expect developmental signals from symbionts, and these organisms develop abnormally if the symbiont signals are not present. Thus Hoffmeyer’s “vertical semiotic system” of genetic communication and “horizontal semiotic system” of ecological communication are integrated during development. (shrink)

Developmental systems theory (DST) is a wholeheartedly epigenetic approach to development, inheritance and evolution. The developmental system of an organism is the entire matrix of resources that are needed to reproduce the life cycle. The range of developmental resources that are properly described as being inherited, and which are subject to natural selection, is far wider than has traditionally been allowed. Evolution acts on this extended set of developmental resources. From a developmental systems perspective, development does not proceed according to (...) a preformed plan; what is inherited is much more than DNA; and evolution is change not only in gene frequencies, but in entire developmental systems. (shrink)

The phenomenon of ‘canalization’ ‐ the genetic capacity to buffer developmental pathways against mutational or environmental perturbations ‐ was first characterized in the late 1930s and early 1940s. Despite enormous subsequent progress in understanding the nature of the genetic material and the molecular basis of gene expression, there have been few attempts to interpret the classical work on canalization in molecular genetic terms. Some recent findings, however, bear on one form of canalization, ‘genetic canalization’, the stabilization of development against mutational (...) effects. These data indicate that co‐expressed paralogous genes can function as mutual ‘back‐up’ elements in developmental processes. Paralogues, however, are far from the only basis of canalization: other genetic sources can be readily envisaged and some of these are described here. The evolutionary questions about genetic canalization and the mechanistic questions about developmental instability that still need to be addressed are also briefly discussed. (shrink)

The concept of plasticity has always been present in the history of developmental biology, both within the theory of epigenesis and within morphogenesis studies. However this tradition relies also upon a genetic conception of plasticity. Founded upon the concepts of ‘‘phenotypic plasticity’’ and ‘‘reaction norm,’’ this genetic conception focuses on the array of possible phenotypic change in relation to diversified environments. Another concept of plasticity can be found in recent publications by some developmental biologists (Gilbert, West-Eberhard). I argue that these (...) authors adopt a ‘‘broad conception of plasticity’’ that is closely related to a notion of development as something that is ongoing throughout an organism’s lifecycle, and has no clear-cut boundaries. However, I suggest that given a narrow conception of plasticity, one can define temporal boundaries for development that are linked to specific features of the morphological process, which are different from behavioral and physiological processes. (shrink)

This special issue of Biological Theory is focused on development; it raises the problem of the temporal and spatial boundaries of development. From a temporal point of view, when does development start and stop? From a spatial point of view, what is it exactly that "develops", and is it possible to delineate clearly the developing entity? This issue explores the possible answers to these questions, and thus sheds light on the definition of development itself.

November 4th-5th, 2012 at Kyoto University. Organizers: Hisashi Nakao & Pierre-Alain Braillard.

The study of evolutionary developmental biology (“evo‐devo”) has recently experienced a dramatic surge in popularity among researchers and theorists concerned with evolution. However, some biologists and philosophers remain skeptical of the claims of evo‐devo. This paper discusses and responds to the recent high profile criticisms of evo‐devo presented by biologists Hopi E. Hoekstra and Jerry A. Coyne. I argue that their objections are unconvincing. Indeed, empirical research supports the main tenets of evo‐devo, including the claim that morphological evolution is the (...) result of cis ‐regulatory change and the distinction that evo‐devo draws between morphological and physiological traits. *Received January 2008; revised March 2009. †To contact the author, please write to: Department of Philosophy, University of Cincinnati, Cincinnati, OH 45221; e‐mail: [email protected]. (shrink)

Organic selection (the Baldwin Effect) by which an environmentally elicitedphenotypic adaptation comes under genotypic control following selectionwas proposed independently in 1896 by the psychologists James Baldwinand Conwy Lloyd Morgan and by the paleontologist Henry Fairfield Osborn.Modified forms of organic selection were proposed as autonomization bySchmalhausen in 1938, as genetic assimilation by Waddington in 1942, andas an explanation for evolution in changing environments or for speciationby Matsuda and West-Eberhard in the 1980s. Organic selection as amechanism mediating proximate environmental effects on the (...) evolution ofmorphology and behaviour is the topic of this essay. Discussion includesthe context in which organic selection was proposed, Lamarckian or neo-Lamarckian implications of organic selection, Waddingtons experimentalstudies demonstrating the existence and efficacy of genetic assimilation,stabilizing selection and norms of reaction favoured by Schmalhausen, andMatsudas search for a mechanism of organic selection in endocrine changesand in heterochrony. (shrink)

Living organisms are currently most often seen as complex dynamical systems that develop and evolve in relation to complex environments. Reflections on the meaning of the complex dynamical nature of living systems show an overwhelming multiplicity in approaches, descriptions, definitions and methodologies. Instead of sustaining an epistemic pluralism, which often functions as a philosophical armistice in which tolerance and so-called neutrality discharge proponents of the burden to clarify the sources and conditions of agreement and disagreement, this paper aims at analysing: (...) (i) what has been Kant's original conceptualisation of living organisms as natural purposes; (ii) how the current perspectives are to be related to Kant's viewpoint; (iii) what are the main trends in current complexity thinking. One of the basic ideas is that the attention for structure and its epistemological consequences witness to a great extent of Kant's viewpoint, and that the idea of organisational stratification today constitutes a different breeding ground within which complexity issues are raised. The various approaches of complexity in biological systems are captured in terms of two different styles, universalism and (weak and strong) constructivism, between which hybrid forms exist. (shrink)

In recent years, a number of philosophers have argued against a biological understanding of the innate in favor of a narrowly psychological notion. On the other hand, Ariew ((1996). Innateness and canalization. Philosophy of Science, 63, S19-S27. (1999). Innateness is canalization: in defense of a developmental account of innateness. In V. Hardcastle (Ed.), Where biology meets psychology: Philosophical essays (pp. 117-138). Cambridge, MA: MIT.) has developed a novel substantial account of innateness based on developmental biology: canalization. The governing thought of (...) this paper is that the notion of the innate, as it re-emerged with the work of Chomsky, is a general notion that applies equally to all biological traits. On this basis, the paper recommends canalization as a promising candidate account of the notion of the innate. (shrink)

We discuss N. I. Vavilov’s 1922 landmark publication, “The Law of Homologous Series in Variation,” and highlight its salient points. Vavilov drew upon his considerable experience in the field with wild and cultivated crop plants and summarized what he noticed in the form of a law. The law stated that comparable variant forms tended to appear in different varieties of the same species, different species of the same genus, different genera of the same family, and so on. His survey of (...) the older literature suggested that the law applied to multicellular animals as well. Vavilov acknowledged that such “parallel” series might be the outcome of convergent evolution (as conventionally understood). At the same time, by way of an alternative hypothesis, he posed a question that continues to engage evolutionary biology to this day. Namely, does the existence of such parallelisms reflect underlying structural and developmental principles (based on the laws of physics and chemistry) which constrain the range of possible plant and animal forms? Vavilov’s original 1922 paper from the _Journal of Genetics_ (12:47–89) is available as supplementary material in the online version of this article. (shrink)

Morphological engineering is an emerging research area in synthetic biology. In 2008 “synthetic morphology” was proposed as a prospective approach to engineering self-constructing anatomies by Jamie A. Davies of the University of Edinburgh. Synthetic morphology can establish a new paradigm, according to Davies, insofar as “cells can be programmed to organize themselves into specific, designed arrangements, structures and tissues.” It is obvious that this new approach will extrapolate morphology into a new realm beyond the traditional logic of morphological research. However, (...) synthetic morphology is a highly idealized vision of morphology which derives its visionary ideas from morphological engineering and mathematical idealizations in order to understand the principles of molecular morphology. Thus, the question is, if this approach will help to understand morphogenesis better or if it will just enable biologists to engineer morphogenesis. The paper investigates the development of synthetic morphology and its relation to synthetic biology as well as its epistemic gains. (shrink)

The French school of theoretical biology has been mainly initiated in Poitiers during the sixties by scientists like J. Besson, G. Bouligand, P. Gavaudan, M. P. Schützenberger and R. Thom, launching many new research domains on the fractal dimension, the combinatorial properties of the genetic code and related amino-acids as well as on the genetic regulation of the biological processes. Presently, the biological science knows that RNA molecules are often involved in the regulation of complex genetic networks as effectors, e.g., (...) activators, inhibitors or hybrids. Examples of such networks will be given showing that there exist RNA “relics” that have played an important role during evolution and have survived in many genomes, whose probability distribution of their sub-sequences is quantified by the Shannon entropy, and the robustness of the dynamics of the networks they regulate can be characterized by the Kolmogorov–Sinaï dynamic entropy and attractor entropy. (shrink)

It is widely recognized that the innate versus acquired distinction is a false dichotomy. Yet many scientists continue to describe certain traits as “innate” and take this to imply that those traits are not acquired, or “unlearned.” This article asks what cognitive role, if any, the concept of innateness should play in the psychological and behavioural sciences. I consider three arguments for eliminating innateness from scientific discourse. First, the classification of a trait as innate is thought to discourage empirical research (...) into its developmental origin. Second, this concept lumps together a number of different biological properties that ought to be treated as distinct. Third, innateness is associated with the outmoded folk biological theory of essentialism. In response to these objections, I consider two attempts to revise the concept of innateness which aim to make it more suitable for scientific explanation and research. One proposal is that innateness can be defined in terms of the biological property of environmental canalization. On this view, a trait is innate to the extent that it is developmentally buffered against a range of different environments. Another proposal is that innateness serves as an explanatory primitive for cognitive science. This view holds that there exist a sharp boundary between psychological and biological explanations and that to identify a trait as innate means that it falls into the latter explanatory domain. This essay ends with some questions for future research. (shrink)

The traditional practice of establishing morphological types and investigating morphological organization has found new support from evolutionary developmental biology (evo-devo), especially with respect to the notion of body plans. Despite recurring claims that typology is at odds with evolutionary thinking, evo-devo offers mechanistic explanations of the evolutionary origin, transformation, and evolvability of morphological organization. In parallel, philosophers have developed non-essentialist conceptions of natural kinds that permit kinds to exhibit variation and undergo change. This not only facilitates a construal of species (...) and higher taxa as natural kinds, but also broadens our perspective on the diversity of kinds found in biology. There are many different natural kinds relevant to the investigative and explanatory aims of evo-devo, including homologues and developmental modules. (shrink)

The 1981 Dahlem conference was a catalyst for contemporary evolutionary developmental biology (Evo-devo). This introductory chapter rehearses some of the details of the history surrounding the original conference and its associated edited volume, explicates the philosophical problem of conceptual change that provided the rationale for a workshop devoted to evaluating the epistemic revisions and transformations that occurred in the interim, explores conceptual change with respect to the concept of evolutionary novelty, and highlights some of the themes and patterns in the (...) different contributions to the present volume, Conceptual Change in Biology: Scientific and Philosophical Perspectives on Evolution and Development. (shrink)

Recent philosophical analyses of the epistemic dimension of images in the sciences show a certain trend in acknowledging potential roles of these images beyond their merely decorative or pedagogical functions. We argue, however, that this new debate has yet paid little attention to a special type of pictures, we call ‘visual metaphor’, and its versatile heuristic potential in organizing data, supporting communication, and guiding research, modeling, and theory formation. Based on a case study of Conrad Hal Waddington’s epigenetic landscape images (...) in biology, we develop a descriptive framework applicable to heuristic roles of various visual metaphors in the sciences. (shrink)

The discovery by Hans Spemann of the “organizer” tissue and its ability to induce the formation of the amphibian embryo’s neural tube inspired leading embryologists to attempt to elucidate embryonic inductions’ underlying mechanism. Joseph Needham, who during the 1930s conducted research in biochemical embryology, proposed that embryonic induction is mediated by a specific chemical entity embedded in the inducing tissue, surmising that chemical to be a hormone of sterol-like structure. Along with embryologist Conrad H. Waddington, they conducted research aimed at (...) the isolation and functional characterization of the underlying agent. As historians clearly pointed out, embryologists came to question Needham’s biochemical approach; he failed to locate the hormone he sought and eventually abandoned his quest. Yet, this study finds that the difficulties he ran into resulted primarily from the limited conditions for conducting his experiments at his institute. In addition, Needham’s research reflected the interests of leading biochemists in hormone and cancer research, because it offered novel theoretical models and experimental methods for engaging with the function of the hormones and carcinogens they isolated. Needham and Waddington were deterred neither by the mounting challenges nor by the limited experimental infrastructure. Like their colleagues in hormone and cancer research, they anticipated difficulties in attempting to establish causal links between complex biological phenomena and simple chemical triggering. (shrink)

This paper analyses the actual meaning of a transcendental philosophy of biology, and does so by exploring and actualising the epistemological and metaphysical value of Kant's viewpoint on living systems. It finds inspiration in the Kantian idea of living systems intrinsically resisting objectification, but critically departs from Kant's philosophical solution in as far as it is based in a subjectivist dogmatism. It attempts to overcome this dogmatism, on the one hand by explicitly taking into account the conditions of possibility at (...) the side of the subject, and on the other hand by embedding both the living and the knowing system into an ontology of complexly organized dynamical systems. This paper fits into the transcendental perspective in acknowledging the need to analyse the conditions of knowability, prior to the contents of what is known. But it also contributes to an expansion and an actualisation of the issue of transcendentality itself by considering the conditions of possibility at the side of the object as intrinsically linked to the conditions of possibility at the side of the subject. (shrink)

This is the story of a textbook that students of developmental biology have used for 45 years. “An Introduction to Embryology” was released soon after a role for genes in the control of development became finally recognized but not yet well documented. Thus this book manifested the transition from embryology to developmental biology. The story of its author, Boris Balinsky, who against all odds survived to write this book, is remarkable on its own. He started his scientific career in the (...) USSR, but due to 20th century social and political upheavals, ended it in South Africa. This article will shed light on the life of Boris Balinsky, a scientist and writer and will explore the origins of his book. BioEssays 27:970–977, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

The discovery by Hans Spemann of the “organizer” tissue and its ability to induce the formation of the amphibian embryo's neural tube inspired leading embryologists to attempt to elucidate embryonic inductions’ underlying mechanism. Joseph Needham, who during the 1930s conducted research in biochemical embryology, proposed that embryonic induction is mediated by a specific chemical entity embedded in the inducing tissue, surmising that chemical to be a hormone of sterol-like structure. Along with embryologist Conrad H. Waddington, they conducted research aimed at (...) the isolation and functional characterization of the underlying agent. As historians clearly pointed out, embryologists came to question Needham's biochemical approach; he failed to locate the hormone he sought and eventually abandoned his quest. Yet, this study finds that the difficulties he ran into resulted primarily from the limited conditions for conducting his experiments at his institute. In addition, Needham's research reflected the interests of leading biochemists in hormone and cancer research, because it offered novel theoretical models and experimental methods for engaging with the function of the hormones and carcinogens they isolated. Needham and Waddington were deterred neither by the mounting challenges nor by the limited experimental infrastructure. Like their colleagues in hormone and cancer research, they anticipated difficulties in attempting to establish causal links between complex biological phenomena and simple chemical triggering. (shrink)

I attempt to raise questions regarding elements of systematics—primarily in the realm of phylogenetic reconstruction—in order to provoke discussion on the current state of affairs in this discipline, and also evolutionary biology in general: e.g., conceptions of homology and homoplasy, hypothesis testing, the nature of and objections to Hennigian “phylogenetic systematics”, and the schism between Darwinian descendants of the “modern evolutionary synthesis” and their supposed antagonists, cladists and punctuationalists.

A standard norm of reaction (NoR) is a graphical depiction of the phenotypic value of some trait of an individual genotype in a population as a function of an environmental parameter. NoRs thus depict the phenotypic plasticity of a trait. The topological properties of NoRs for sets of different genotypes can be used to infer the presence of (non-linear) genotype-environment interactions. While it is clear that many NoRs are adaptive, it is not yet settled whether their evolutionary etiology should be (...) explained by selection on the mean phenotypic trait values in different environments or whether there are specific genes conferring plasticity. If the second alternative is true the NoR is itself an object of selection. Generalized NoRs depict plasticity at the level of populations or subspecies within a species, species within a genus, or taxa at higher levels. Historically, generalized NoRs have routinely been drawn though rarely explicitly recognized as such. Such generalized NoRs can be used to make evolutionary inferences at higher taxonomic levels in a way analagous to how standard NoRs are used for microevolutionary inferences. (shrink)

The theory of concepts advanced in the dissertation aims at accounting for a) how a concept makes successful practice possible, and b) how a scientific concept can be subject to rational change in the course of history. Traditional accounts in the philosophy of science have usually studied concepts in terms only of their reference; their concern is to establish a stability of reference in order to address the incommensurability problem. My discussion, in contrast, suggests that each scientific concept consists of (...) three components of content: 1) reference, 2) inferential role, and 3) the epistemic goal pursued with the concept's use. I argue that in the course of history a concept can change in any of these three components, and that change in one component—including change of reference—can be accounted for as being rational relative to other components, in particular a concept's epistemic goal.This semantic framework is applied to two cases from the history of biology: the homology concept as used in 19th and 20th century biology, and the gene concept as used in different parts of the 20th century. The homology case study argues that the advent of Darwinian evolutionary theory, despite introducing a new definition of homology, did not bring about a new homology concept (distinct from the pre-Darwinian concept) in the 19th century. Nowadays, however, distinct homology concepts are used in systematics/evolutionary biology, in evolutionary developmental biology, and in molecular biology. The emergence of these different homology concepts is explained as occurring in a rational fashion. The gene case study argues that conceptual progress occurred with the transition from the classical to the molecular gene concept, despite a change in reference. In the last two decades, change occurred internal to the molecular gene concept, so that nowadays this concept's usage and reference varies from context to context. I argue that this situation emerged rationally and that the current variation in usage and reference is conducive to biological practice.The dissertation uses ideas and methodological tools from the philosophy of mind and language, the philosophy of science, the history of science, and the psychology of concepts. (shrink)

The increasing application of network models to interpret biological systems raises a number of important methodological and epistemological questions. What novel insights can network analysis provide in biology? Are network approaches an extension of or in conflict with mechanistic research strategies? When and how can network and mechanistic approaches interact in productive ways? In this paper we address these questions by focusing on how biological networks are represented and analyzed in a diverse class of case studies. Our examples span from (...) the investigation of organizational properties of biological networks using tools from graph theory to the application of dynamical systems theory to understand the behavior of complex biological systems. We show how network approaches support and extend traditional mechanistic strategies but also offer novel strategies for dealing with biological complexity. (shrink)

A central reason that undergirds the significance of evo-devo is the claim that development was left out of the Modern synthesis. This claim turns out to be quite complicated, both in terms of whether development was genuinely excluded and how to understand the different kinds of embryological research that might have contributed. The present paper reevaluates this central claim by focusing on the practice of model organism choice. Through a survey of examples utilized in the literature of the Modern synthesis, (...) I identify a previously overlooked feature: exclusion of research on marine invertebrates. Understanding the import of this pattern requires interpreting it in terms of two epistemic values operating in biological research: theoretical generality and explanatory completeness. In tandem, these values clarify and enhance the significance of this exclusion. The absence of marine invertebrates implied both a lack of generality in the resulting theory and a lack of completeness with respect to particular evolutionary problems, such as evolvability and the origin of novelty. These problems were salient to embryological researchers aware of the variation and diversity of larval forms in marine invertebrates. In closing, I apply this analysis to model organism choice in evo-devo and discuss its relevance for an extended evolutionary synthesis. (shrink)

Experimental evidence strongly supports the view that the subdivision of organ anlagen into smaller structural units is an autonomous process. Dalcq &Pasteels' hypothesis which says that the boundaries between the different areas into which a morphogenetic field differentiates are determined by “Threshold values” in the “potential” of the field in question, is inconsistent with our present knowledge of biochemical reaction systems. Threshold values may only be used indescribing the spatial differentiation of a morphogenetic field. It is suggested that the latter (...) concept be replaced by the concept of “optimal values” in the intensity of a morphogenetic field-specific for the various chemo-differentiations characterizing the different regions into which a morphogenetic field will split up-and that each optimal value isdeterminative for the appearance of one particular differentiation within the morphogenetic field, each differentiation being formed within a certain range of intensity of the field. On the basis of the hypothesis formulated above a “virginal” morphogenetic field will necessarily differentiate into a number of smaller fields of second order, which in their turn will split up into fields of third order, etc. ” Pattern formation” may be defined as the differentiation of a morphogenetic field into an increasing number of smaller fields of higher order of qualitative different chemical and structural composition. Since differentiation of a morphogenetic field proceeds autonomously, the capacity for pattern formation is an intrinsic property of a morphogenetic field. In the light of these considerations it is suggested that a morphogenetic field action is responsible for the first differentiation of the developing embryo into regions with predominantly ectodermal, mesodermal or endodermal differentiation tendencies. The present knowledge about the characteristic pattern formation taking place in the axial mesoderm as well as in the overlying neural plate seems to be in good agreement with the implications of the present morphogenetic field concept. It is emphasized, however, that if the present morphogenetic field concept cannot be characterized further biochemically and biophysically, it will have to be replaced by another concept which can be defined more sharply and is more easily accessible to experimental analysis. Les preuves expérimentales confirment que la subdivision des ébauches des organes en unités structurelles plus petites est un processus autonome. L'hypothèse deDalcq &Pasteels disant que les bornes entre les différents domaines formées par la différenciation d'un champ morphogénétique sont déterminées par des „valeurs seuil” dans le „potentiel” du champ en question, n'est pas en harmonie avec notre connaissance actuelle des systèmes biochimiques. Des “valeurs seuil” ne peuvent être employés qu'en décrivant la différenciation spatiale d'un champ morphogénétique. On prend en considération de remplacer le concept des “valeurs seuil” par le concept des “valeurs optimales” dans l'intensité d'un champ morphogénétique. Ce seraient les valeurs spécifiques aux différenciations chimiques diverses qui caractérisent les différents domaines dans lesquels un champ morphogénétique se différencie. En outre, chaque valeur optimale serait déterminative à la formation d'une différenciation spéciale dans le champ morphogénétique, chaque différentiation se formant dans un certain trajet de l'intensité du champ. Par suite de l'hypothèse formulée ci-dessus un champ morphogénétique “virginal” va nécessairement se différencier en un nombre de champs plus petits de deuxième ordre, qui à leur tour se divisent en champs d'ordre troisième, etc. ... La régionalisation peut être définie comme la différenciation d'un champ morphogénétique dans un nombre de plus en plus élevé de champs plus petits d'ordre supérieur de composition chimique et structurelle qualitativement différente. Parce que la différenciation d'un champ morphogénétique se produit de façon autonome, le pouvoir de régionalisation est une propriété intrinsique d'un champ morphogénétique. Ces considérations nous mènent à proposer que l'action d'un champ morphogénétique est responsable de la première différenciation de l'embryon en régions qui possèdent des tendences de différenciation principalement ectodermiques, mésodermiques, ou bien endodermiques. La connaissance actuelle concernant la régionalisation caractéristique qui se produit dans le mésoderme axial ainsi que dans la plaque neurale superposée paraît se conformer aux conséquences du concept de champ morphogénétique. Cependant on souligne le fait que dans le cas òu le concept actuel du champ morphogénétique ne pourra pas être plus amplement caractérisé de façon biochimique et biophysique, il faudra le remplacer par un autre concept qui puit être défini plus nettement et qui est mieux accessible à l'analyse expérimentale. Die Auffassung, dass die Aufteilung von Organanlagen in kleineren Struktureinheiten ein selbständiger Prozess ist, findet Bestätigung in den experimentellen Ergebnissen. Die Hypothese vonDalcq &Pasteels , dass die Grenzen zwischen den unterschiedenen Gebieten, in denen ein morphogenetisches Feld sich differenziert, durch “Schwellenwerte” im “Potential” des genannten Feldes bestimmt werden, ist unvereinbar mit unserem heutigen Wissen über biochemischen Reaktionssystemen. Der Gebrauch des Begriffs “Schwellenwert” ist nur gestattet bei der Beschreibung der räumlichen Differenzierung eines morphogenetischen Feldes. Statt dieses Begriffs wird der Begriff “Optimaler Wert” vorgeschlagen; Werte also in der Intensität eines morphogenetischen Feldes, optimal und spezifisch für die verschiedene Chemodifferenzierungen, welche die Gebiete kennzeichnen, in denen ein morphogenetisches Feld sich differenzieren wird. Jeder optimaler Wert soll dann das Erscheinen einer bestimmten Differenzierung innerhalb des morphogenetischen Feldes veranlassen, welche Differenzierung sich bildet innerhalb eines bestimmten Bereichs der Feldintensität. Auf Grund der obigen Hypothese wird ein “virginelles” morphogenetisches Feld zwangsläufig sich differenzieren in eine Anzahl kleinerer Feldern zweiten Grades; diese in Felder dritten Grades, usw. Musterbildung könnte definiert werden als die Differenzierung eines morphogenetischen Feldes in eine zunehmende Anzahl kleinerer Felder höheren Grades von qualitativ verschiedener chemischen und strukturellen Zusammensetzung, Weil diese Differenzierung autonom vor sich geht, ist das Vermögen zur Musterbildung eine innewohnende Eigenschaft eines morphogenetischen Feldes. Im Lichte dieser Betrachtungen ist es naheliegend anzunehmen dass eine morphogenetische Feldwirkung verantwortlich ist für die erste Differenzierung des sich entwickelnden Embryos in Gebiete überwiegend ektodermalen, mesodermalen oder entodermalen Differenzierungstendenzen. Die heutigen Kenntnisse über die charakteristische Musterbildung im axialen Teil des Mesoderms und in der überliegenden Neuralplatte scheinen in guter Übereinstimmung zu sein mit den des morphogenetischen Feldbegriffs. Dennoch wird benachdruckt, dass, falls das gegenwärtige morphogenetische Feldbegriff nicht weiter biochemisch und biophysisch gekennzeichnet werden kann, anstatt dessen ein anderer Begriff entwickelt werden muß, der schärfer definiert werden kann und besser zugänglich ist für experimentelle Analyse. (shrink)

The so-called evolutionary social scienccs are based on the belief that Darwinism can explain the living world and that it therefore should be able to explain other complex systems such as minds and societies. In fact, Darwinism cannot explain biological evolution. It does make an important contribution, but this is towards understanding adaptation, which is a major problem in biology but not in the social sciences. Darwinism has much less to offer to the social sciences than to biology and the (...) shortcomings it brings with it are much greater. (shrink)

This article examines and rejects the claim that 'innateness is canalization'. Waddington's concept of canalization is distinguished from the narrower concept of environmental canalization with which it is often confused. Evidence is presented that the concept of environmental canalization is not an accurate analysis of the existing concept of innateness. The strategy of 'biologicizing the mind' by treating psychological or behavioral traits as if they were environmentally canalized physiological traits is criticized using data from developmental psychobiology. It is concluded that (...) identifying innateness with environmental canalization can only result in adding unhelpful associations from 'folkbiology' to the relatively precise idea of canalization. (shrink)