Developmental Biology, Misc

It has become somewhat of a platitude to call Aristotle the first epigenesist insofar as he thought form and structure emerged gradually from an unorganized, amorphous embryo. But modern biology now recognizes two senses of “epigenesis”. The first is this more familiar idea about the gradual emergence of form and structure, which is traditionally opposed to the idea of preformationism. But modern biologists also use “epigenesis” to emphasize the context-dependency of the process itself. Used in this sense development is not (...) simply the unfolding of a pre-determined sequence of changes specified in advance by the organism’s genotype. It is also sensitive to inputs from the internal and external environment, which help determine in real-time which of the many potential developmental pathways are actualized during the process. Within this paradigm developing embryos are viewed as dynamic and responsive systems that react to inputs from the internal and external environment ‘on the fly’. In this paper I argue that, while Aristotle was an epigenesist in the first sense, he would have rejected epigenesis in the more modern sense. First, Aristotle’s model of choice for a developing embryo is the automaton that executes a set of preset movements (GA 734b9-13, 741b7-15). The automatons he has in mind are not dynamic AI systems capable of modifying their behaviour on the fly in response to environmental cues but completely deterministic mechanisms whose movements are fixed by their original design. Second, given Aristotle’s views about the different kinds of causal powers there are, it looks like only intentional agents endowed with actual decision-making powers could be capable of the sort of plasticity at the core of a more dynamic epigenesis. For that kind of epigenesis requires powers for alternative outcomes, and Aristotle is explicit that such powers require rational desires (προαίρεσις) that control which of those alternatives to bring about. If I am right, then he could not have made sense of the idea of a developing embryo (as a non-intentional system) making adjustments to its phenotype on the fly in response to emerging problems and opportunities, given the conceptual resources available to him. (shrink)

The recent literature on causality has seen the introduction of several distinctions within causality, which are thought to be important for understanding the widespread scientific practice of focusing causal explanations on a subset of the factors that are causally relevant for a phenomenon. Concepts used to draw such distinctions include, among others, stability, specificity, proportionality, or actual-difference making. In this contribution, I propose a new distinction that picks out an explanatorily salient class of causes in biological systems. Some select causes (...) in complex biological systems, I argue, have the property of enabling coherent causal control of these systems. Examples of such control variables include hormones and other signaling molecules, e.g., TOR (target of rapamycin), morphogens or the products of homeotic selector genes in embryonic pattern formation. I propose an analysis of this notion based on concepts borrowed from causal graph theory. (shrink)

The history of developmental biology is interwoven with debates as to whether mechanistic explanations of development are possible or whether alternative explanatory principles or even vital forces need to be assumed. In particular, the demonstrated ability of embryonic cells to tune their developmental fate precisely to their relative position and the overall size of the embryo was once thought to be inexplicable in mechanistic terms. Taking a causal perspective, this Element examines to what extent and how developmental biology, having turned (...) molecular about four decades ago, has been able to meet the vitalist challenge. It focuses not only on the nature of explanations but also on the usefulness of causal knowledge – including the knowledge of classical experimental embryology – for further scientific discovery. It also shows how this causal perspective allows us to understand the nature and significance of some key concepts, including organizer, signal and morphogen. This title is also available as Open Access on Cambridge Core. (shrink)

Living fossils, taxa with similar members now and in the deep past, have recently come under scrutiny. Those who think the concept should be retained have argued for its epistemic and normative utility. This article extends the epistemic utility of the living fossils concept to include ways in which a taxon’s living fossil status can serve as evidence for other claims about that taxon. I will use insights from developmental biology to refine these claims. Insofar as these considerations demonstrate the (...) epistemic utility of the living fossils concept, they support retaining the concept and using it in biological research. (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 article offers a characterization of what I call multiple-models juxtaposition, a strategy for managing trade-offs among modeling desiderata. MMJ displays models of distinct phenomena to...

An atom is characterized mathematically as an evolving superposition of possible values of properties and experimentally as an instantaneous phenomenon with a precise value of a measured property. Likewise, an organism is to itself a flux of experience and to an observer a tangible body in a distinct moment. Whereas the implicit atom is the stream of computation represented by the smoothly propagating wave function, the implicit organism is both the species from which the body individuates and the personal mind (...) its behavior explicates. As with the wave computation that underlies the atom, the substance of the implicit organism is not matter but information. And like projection from a superposition of potential values to a single outcome in a precise and fleeting moment, the organism actualizes only one of the many possible behaviors calculated in the ongoing presence we know as consciousness. (shrink)

There have been repeated attempts in the history of comparative biology to provide a mechanistic account of morphological homology. However, it is well-established that homologues can develop from diverse sets of developmental causes, appearing not to share any core causal architecture that underwrites character identity. We address this challenge with a new conceptual model of Character Identity Mechanisms. ChIMs are cohesive mechanisms with a recognizable causal profile that allows them to be traced through evolution as homologues despite having a diverse (...) etiological organization. Our model hypothesizes that anatomical units at different levels of organization—cell types, tissues, and organs—have level-specific ChIMs with different conserved parts, activities, and organization. Relying on a methodology of conceptual engineering, we show how the ChIM concept advances our understanding of the developmental basis of morphological characters, while forging an important link between comparative and mechanistic biology. (shrink)

Has science already answered the fundamental questions about the concepts of Life, Cosmos and Evolution? Has science not relegated these fundamental questions by following up on more immediate, “useful” and practical endeavors that ultimately ensure that the wheel of capitalism keeps spinning in its frantic search for material and economic progress? There is something terribly wrong with the current theory of evolution, understood as the Darwinian theory with its successive versions and extensions. The concept of natural selection, the cornerstone of (...) Darwinism, is logically inconsistent. This has been demonstrated in some of my latest academic publications. The entire conceptual framework of Darwinism is inadequate. Organisms do not compete with each other for the survival of the fittest. The fundamental relationship in Nature is not competition or confrontation, but interconnectivity, complementarity, and relational meaningfulness. A new theory of evolution is necessary to explain how it is possible that organisms as simple as bacteria, protozoa and diatoms could have generated organisms as complex as primates, and among them, the human being, a being capable of feeling and thinking, of suffering and enjoying, a being capable of having ideals and purposes. A theory that explains how it is possible that this being so complex, rich, and to some extent still unknown, has emerged from a single cell, an egg-cell, lacking all the capacities, riches and depths of human existence. Such a theory already exists. (shrink)

In this work I propose a theory of evolution as a process of unfolding. This theory is based on four logically concatenated principles. The principle of evolutionary order establishes that the more complex cannot be generated from the simpler. The principle of origin establishes that there must be a maximum complexity that originates the others by logical deduction. Finally, the principle of unfolding and the principle of actualization guarantee the development of the evolutionary process from the simplest to the most (...) complex. These logical principles determine the existence of a virtual ideological matrix that contains the sequence of the preformed and folded morphogenetic fields. In this manner, the evolutionary process consists of the sequential unfolding and actualization of these fields, which is motorized by a process of teleologization carried out by the opening consciousness of the forms included in the fields of the ideological matrix. This theory leads to a radical change of perspective regarding the materialist worldview, and places life at the center of the evolutionary process as an activity carried out by a consciousness that seeks to fulfill a purpose by actualizing its own potentialities. (shrink)

In this work the doctrine of organicism will be addressed, as explained and seen mainly by Bertalanffy. We will study how this doctrine represents and embodies the ambiguity of Kantian teleology as a regulative principle, and how this same problem leads to consider a real problem as a knowledge problem. It will be concluded that organicism, conceived in this way, does not represent a true holism, but what we will call a syn-holism, a synthesis or assembly, and that to obtain (...) a true holism we must resort to the concept of true form. Finally, it will be established that since the fundamental characteristic of an organism is its development, a historical theory of the organism is required for which the concept of field can be useful and necessary. (shrink)

Efforts from diverse disciplines, including evolutionary studies and biomechanical experiments, have yielded new insights into the genetic, signaling, and mechanical control of tooth formation and functions. Evidence from fossils and non‐model organisms has revealed that a common set of genes underlie tooth‐forming potential of epithelia, and changes in signaling environments subsequently result in specialized dentitions, maintenance of dental stem cells, and other phenotypic adaptations. In addition to chemical signaling, tissue forces generated through epithelial contraction, differential growth, and skeletal constraints act (...) in parallel to shape the tooth throughout development. Here recent advances in understanding dental development from these studies are reviewed and important gaps that can be filled through continued application of evolutionary and biomechanical approaches are discussed. (shrink)

Despite their diversity and ecological importance, many areas of the SAR—Stramenopila, Alveolata, and Rhizaria—clade are poorly understood as the majority (90%) of SAR species lack molecular data and only 5% of species are from well‐sampled families. Here, we review and summarize the state of knowledge about the three major clades of SAR, describing the diversity within each clade and identifying synapomorphies when possible. We also assess the “dark area” of SAR: the morphologically described species that are missing molecular data. The (...) majority of molecular data for SAR lineages are characterized from marine samples and vertebrate hosts, highlighting the need for additional research effort in areas such as freshwater and terrestrial habitats and “non‐vertebrate” hosts. We also describe the paucity of data on the biogeography of SAR species, and point to opportunities to illuminate diversity in this major eukaryotic clade. (shrink)

Despite their diversity and ecological importance, many areas of the SAR—Stramenopila, Alveolata, and Rhizaria—clade are poorly understood as the majority of SAR species lack molecular data and only 5% of species are from well-sampled families. Here, we review and summarize the state of knowledge about the three major clades of SAR, describing the diversity within each clade and identifying synapomorphies when possible. We also assess the “dark area” of SAR: the morphologically described species that are missing molecular data. The majority (...) of molecular data for SAR lineages are characterized from marine samples and vertebrate hosts, highlighting the need for additional research effort in areas such as freshwater and terrestrial habitats and “non-vertebrate” hosts. We also describe the paucity of data on the biogeography of SAR species, and point to opportunities to illuminate diversity in this major eukaryotic clade. See also the video abstract here: https://youtu.be/_VUXqaX19Rw. Despite their diversity, abundance, and importance, fewer than 10% of the species within the SAR—Stramenopila, Alveolata, and Rhizaria—clade have been assessed using molecular tools. Only a small percentage of the molecular records contain information on ecology or have associate location data, indicating a tremendous dark area. (shrink)

Here we evaluate our current understanding of the function of the nervous system in Hydra, a non‐bilaterian animal which is among the first metazoans that contain neurons. We highlight growing evidence that the nervous system, with its rich repertoire of neuropeptides, is involved in controlling resident beneficial microbes. We also review observations that indicate that microbes affect the animal's behavior by directly interfering with neuronal receptors. These findings provide new insight into the original role of the nervous system, and suggest (...) that it emerged to orchestrate multiple functions including host‐microbiome interactions. The excitement of future research in the Hydra model now relies on uncovering the common rules and principles that govern the interaction between neurons and microbes and the extent to which such laws might apply to other and more complex organisms. (shrink)

Until recently, the ocular surface is thought by many to be sterile and devoid of living microbes. It is now becoming clear that this may not be the case. Recent and sophisticated PCR analyses have shown that microbial DNA‐based “signatures” are present within various ethnic, geographic, and contact lens wearing communities. Furthermore, using a mouse model of ocular surface disease, we have shown that the microbe, Corynebacterium mastitidis (C. mast), can stably colonize the ocular mucosa and that a causal relationship (...) exists between ocular C. mast colonization and beneficial local immunity. While this constitutes proof‐of‐concept that a bona fide ocular microbiome that tunes immunity can exist at the ocular surface, there remain numerous unanswered questions to be addressed before microbiome‐modulating therapies may be successfully developed. Here, the authors will briefly outline what is currently known about the local ocular microbiome as well as microbiomes associated with other sites, and how those sites may play a role in ocular surface immunity. Understanding how commensal microbes affect the ocular surface immune homeostasis has the potential revolutionize how we think about treating ocular surface disease. (shrink)

This is an epistemologically-driven history of the concept of evolution. Starting from its inception, this work will follow the development of this pregnant concept. However, in contradistinction to previous attempts, the objective will not be the identification of the different meanings it adopted through history, but conversely, it will let the concept to be unfolded, to be explicated and to express its own inner potentialities. The underlying thesis of the present work is, therefore, that the path that leads to the (...) development of the concept of evolution is the path that studies the possibilities of the evolution of concepts, and that the historical reconstruction of its conceptual trajectory will shed light into potential and unexploited possibilities. This methodology will provide useful tools and resources for future developments of the concept. For example, it will define the concept of transmutation as a different conceptual trajectory deviating from the one corresponding to evolution, at the onset of the 19th century. Moreover, epigenesis will not be the opposing concept to evolution, but only to simultaneous and instantaneous generation. It will demonstrate that every important system of epigenesis drew upon some kind of formative power to explain development. More importantly, it will show that the problem of preformation cannot be overlooked, and that some kind of virtual preformation must be considered in order to address the problems of generation and development. (shrink)

A common view of how-possibly explanations in biology treats them as explanatorily incomplete. In addition to this interpretation of how-possibly explanation, I argue that there is another interpretation, one which features what I term “explanatory strategies.” This strategy-centered interpretation of how-possibly explanation centers on there being a different explanatory context within which how-possibly explanations are offered. I contend that, in conditions where this strategy context is recognized, how-possibly explanations can be understood as complete explanations. I defend this alternative interpretation by (...) analyzing the explanatory value of simple physical models the nineteenth century developmental biologist Wilhelm His constructed for animal development. (shrink)

Evolutionary developmental biology represents a paradigm shift in the understanding of the ontogenesis and evolutionary progression of the denizens of the natural world. Given the empirical successes of the evo-devo framework, and its now widespread acceptance, a timely and important task for the philosophy of biology is to critically discern the ontological commitments of that framework and assess whether and to what extent our current metaphysical models are able to accommodate them. In this paper, I argue that one particular model (...) is a natural fit: an ontology of dispositional properties coherently and adequately captures the crucial casual-cum-explanatory role that the fundamental elements of evo-devo play within that framework. (shrink)

The biological sciences have always proven a fertile ground for philosophical analysis, one from which has grown a rich tradition stemming from Aristotle and flowering with Darwin. And although contemporary philosophy is increasingly becoming conceptually entwined with the study of the empirical sciences with the data of the latter now being regularly utilised in the establishment and defence of the frameworks of the former, a practice especially prominent in the philosophy of physics, the development of that tradition hasn’t received the (...) wider attention it so thoroughly deserves. This review will briefly introduce some recent significant topics of debate within the philosophy of biology, focusing on those whose metaphysical themes (in everything from composition to causation) are likely to be of wide-reaching, cross-disciplinary interest. (shrink)

Ontologies of living things are increasingly grounded on the concepts and practices of current life science. Biological development is a process, undergone by living things, which begins with a single cell and (in an important class of cases) ends with formation of a multicellular organism. The process of development is thus prima facie central for ideas about biological individuality and organismality. However, recent accounts of these concepts do not engage developmental biology. This paper aims to fill the gap, proposing the (...) lineage view of stem cells as an ontological framework for conceptualizing organismal development. This account is grounded on experimental practices of stem cell research, with emphasis on new techniques for generating biological organization in vitro. On the lineage view, a stem cell is the starting point of a cell lineage with a specific organismal source, time-interval of existence, and ‘tree topology’ of branch-points linking the stem to developmental termini. The concept of ‘enkapsis’ accommodates the cell-organism relation within the lineage view; this hierarchical notion is further explicated by considering the methods and results of stem cell experiments. Results of this examination include a (partial) characterization of stem cells’ developmental versatility, and the context-dependence of developmental processes involving stem cells. (shrink)

Nach neodarwinistischem Verständnis der Evolution entstehen neue Organismen letztlich durch rein zufällige Mutationsprozesse auf genetischer Ebene. Ihre Überlebenschancen werden dann durch die jeweilig herrschende Umwelt begünstigt oder unterdrückt. Die Evolution ist demnach nur vom reinen Zufall geleitet. Neuere Einsichten aus Entwicklungsbiologie (EvoDevo) und Epigenetik haben unsere Sicht der Evolutionsabläufe jedoch deutlich erweitert. Dabei kommt der Umwelt eine lenkende Rolle zu, der reine Zufall verliert an Bedeutung. Damit lässt sich naturwissenschaftliches Verständnis wieder besser mit herkömmlichen Schöpfungsbildern versöhnen.

Is life a simple result of a conjunction of physico-chemical processes? Can be reduced to a mere juxtaposition of spatially determined events? What epistemology or world-view allows us to comprehend it? Aristotle built a novel philosophical system in which nature is a dynamical totality which is in constant movement. Life is a manifestation of it, and is formed and governed by the psyche. Psyche is the organizational principle of the different biological levels: nutritive, perceptive and intelective. Driesch's crucial experiment provided (...) empirical proof of the principle of life, which he called entelechy. Entelechy is an intensive manifoldness and cannot be comprehended by the usual extensive parameters. The entelechian's own ambiance is duration. This allows the reintroduction of the concept of teleology in the sphere of the living, understood not as a final cause, but as an order born from desire and leading to action. (shrink)

Is it true that there is an analogy between modes of creation and such of perception? Respective to the cultural anthropological research of Ernst Cassirer, Susanne K. Langer and John M. Krois and by the analysis of a tape of the Swiss video-artist Pipilotti Rist this initial thesis of Formal Aesthetics shall be supported. - I - -/- Lässt sich die Behauptung stützen, dass zwischen Gestaltungsweisen und Wahrnehmungsweisen eine Analogie besteht? Aufbauend auf den kulturanthropologischen Forschungen von Ernst Cassirer, Susanne K. (...) Langer und John M. Krois sowie der Analyse eines Tapes der Schweizer Videokünstlerin Pipilotti Rist gilt es diese ursprünglich von der formalen Ästhetik aufgeworfene These zu untermauern. (shrink)

This article examines the, hitherto comparatively unexplored, reception of Greek embryology by medieval Muslim jurists. The article elaborates on the views attributed to Hippocrates (d. ca. 375 BC), which received attention from both Muslim physicians, such as Avicenna (d. 1037), and their Jewish peers living in the Muslim world including Ibn Jumayʽ (d. ca. 1198) and Moses Maimonides (d. 1204). The religio-ethical implications of these Graeco-Islamic-Jewish embryological views were fathomed out by the two medieval Muslim jurists Shihāb al-Dīn al-Qarāfī (d. (...) 1285) and Ibn al-Qayyim (d. 1350). By putting these medieval religio-ethical discussions into the limelight, the article aims to argue for a two-pronged thesis. Firstly, pre-modern medical ethics did exist in the Islamic tradition and available evidence shows that this field had a multidisciplinary character where the Islamic scriptures and the Graeco-Islamic-Jewish medical legacy were highly intertwined. This information problematizes the postulate claiming that medieval Muslim jurists were hostile to the so-called ‘ancient sciences’. Secondly, these medieval religio-ethical discussions remain playing a significant role in shaping the nascent field of contemporary Islamic bioethics. However, examining the exact character and scope of this role still requires further academic ventures. (shrink)

In the atavistic model of cancer progression, tumor cell dedifferentiation is interpreted as a reversion to phylogenetically earlier capabilities. The more recently evolved capabilities are compromised first during cancer progression. This suggests a therapeutic strategy for targeting cancer: design challenges to cancer that can only be met by the recently evolved capabilities no longer functional in cancer cells. We describe several examples of this target‐the‐weakness strategy. Our most detailed example involves the immune system. The absence of adaptive immunity in immunosuppressed (...) tumor environments is an irreversible weakness of cancer that can be exploited by creating a challenge that only the presence of adaptive immunity can meet. This leaves tumor cells more vulnerable than healthy tissue to pathogenic attack. Such a target‐the‐weakness therapeutic strategy has broad applications, and contrasts with current therapies that target the main strength of cancer: cell proliferation. (shrink)

“Indeed, we now know that the proportion of genetic sequences on earth that belongs to visible organisms is negligible. Furthermore, only 15% of the genetic sequences found in the samples from the environment and from feces analyzed in metagenomic studies belong to the three domains of microbes currently recognized in the tree-of-life framework – bacteria, archaea, and eukaryotes. Viruses contain another 15-30% of these genetic sequences.” This means that the majority of unidentified genetic sequences pose an unresolved problem. Where do (...) they come from? New genes suddenly appear, called ORFans (“orphan genes”) without any precursors. They may be produced by gene duplication, or fusion, or some other unknown process. Yet, Darwin’s tree of life concept would make it impossible to consider such processes. The transfer of genetic sequences from parasites to hosts could involve hundreds of genes for bacteria or viruses. But, as Raoult writes, “the current classification of the domains of life is based on the ribosome – the production apparatus of proteins – which does not exist in these viruses.” Adherence to the dogmatism of Darwin thus prevents these new discoveries, that overturn his century-and-a-half old teachings, from ever reaching the new generation of scientists. Raoult concludes, "Genetic research, in particular, must be free to find new models to explain, and enhance, twenty-first-century scientific discovery. Today, Darwin’s theory of evolution is more a hindrance than a help, because it has become a quasi-theological creed that is preventing the benefits of improved research from being fully realized.". (shrink)

The study of organisms within the range of their existence from fertilization to birth is referred to as embryology. The process of progressive change during that period is called development. That development does not stop at birth but continues on throughout the entire life-span of the organism as the process of growth and decay — catabolism, anabolism, and metabolism. The study of this entire range of life has recently become known as developmental biology. The belief that the development from an (...) initial stage of a fertilized egg or zygote to a fully formed adult represents, in compressed time, the whole process of evolution that occurred over millions of years, has recently been named evo-devo, or evolutionary development. The more science advances, the more it studies Nature in its intimate details, the more it comes to realize the existence of a pervasive reason, an inherent natural intelligence that is working in even the most insignificant portions of the universe. Francis Bacon (1561–1626) said, “A little philosophy (science) inclineth man's mind to atheism, but depth in philosophy (science) bringeth men's minds about to religion.” This point is especially true today. It is not from ignorance that men come to have faith in God, but from a maturity of reason and experience. Vedanta philosophy teaches that there is a conscious intelligence that underlies all experienced existence. Being self-evident, this should hardly have to be argued. Yet modern science has failed to integrate this truth into its materialist/naturalistic paradigm. Correcting this deficiency will be the challenge of 21st century science, and the highest reward for humanity. (shrink)

The aim of this paper is to describe and analyze the epistemological justification of a proposal initially made by the bio-mathematician Robert Rosen in 1958. In this theoretical proposal, Rosen suggests using the mathematical concept of « category » and the correlative concept of « natural equivalence » in mathematical modeling applied to living beings. Our questions are the following: according to Rosen, to what extent does the mathematical notion of category give access to more « natural » formalisms in (...) the modeling of living beings? Is the so-called « naturalness » of some kinds of equivalences (which the mathematical notion of category makes it possible to generalize and to put at the forefront) analogous to the naturalness of living systems? Rosen appears to answer « yes » and to ground this transfer of the concept of « natural equivalence » in biology on such an analogy. But this hypothesis, although fertile, remains debatable. Finally, this paper makes a brief account of the later evolution of Rosen’s arguments about this topic. In particular, it sheds light on the new role played by the notion of « category » in his more recent objections against computational models that since the 1990’s are pervading almost every domain of biology. (shrink)

Many apparently complex mechanisms in biology, especially in embryology and molecular biology, can be explained easily by reasoning at the level of the “efficient cause” of the observed phenomenology: the mechanism can then be explained by a simple geometrical argument or a variational principle, leading to the solution of an optimization problem, for example, via the co-existence of a minimization and a maximization problem . Passing from a microscopic level to the macroscopic level often involves an averaging effect that gives (...) birth to a global functional feature . We will illustrate these general principles by building in four different domains of application “a minima” models and showing the main properties of their solutions: extraction of a minimal RNA structure functioning as the first “peptidic machine,” a kind of ancestral ribosome; study of a genetic regulatory network of Drosophila centred on Engrailed gene and expressing successively two genes inside a limit cycle; study of a genetic network regulating neural activity and proliferation in mammals; and study of a simple geometric model of epiboly in zebrafish. (shrink)

This article unpacks a particular use of ‘cases’ within developmental biology, namely as a means of describing the typical or canonical patterns of phenomena. The article explores how certain cases have come to be established within the field and argues that although they were initially selected for reasons of convenience or ease of experimental manipulation, these cases come to serve as key reference points within the field because of the epistemological structures imposed on them by the scientists using them and, (...) hence, become usable in a wider variety of circumstances including future theory development. (shrink)

The focus of this article is the analysis of generative mechanisms, a basic concept and phenomenon within the metatheoretical perspective of critical realism. It is emphasized that research questions and methods, as well as the knowledge it is possible to attain, depend on the basic view – ontologically and epistemologically – regarding the phenomenon under scrutiny. A generative mechanism is described as a trans empirical but real existing entity, explaining why observable events occur. Mechanisms are mostly possible to grasp only (...) indirectly by analytical work, based however on empirical observations. In order to achieve such an explanatory analysis, five methodological steps are suggested and discussed, among them abduction and retroduction. These steps are illustrated throughout by examples drawn from empirical research regarding social work practice. The article is concluded with a discussion of the need for knowledge of generative mechanisms. (shrink)

The Presidential Commission for the Study of Bioethical Issues released its first report, New Directions: The Ethics of Synthetic Biology and Emerging Technologies, on December 16, 2010.1 President Barack Obama had requested this report following the announcement last year that the J. Craig Venter Institute had created the world’s first self-replicating bacterial cell with a completely synthetic genome. The Venter group’s announcement marked a significant scientific milestone in synthetic biology, an emerging field of research that aims to combine the knowledge (...) and methods of biology, engineering, and related disciplines in the design of chemically synthesized DNA to create organisms with novel or enhanced .. (shrink)

Despite the radical importance of embryology in the development of organi- cism, developmental biology remains philosophically underexplored as a theoretical and empirical resource to clarify the nature of organisms. This paper discusses how embryology can help develop the organisational definition of the organism as a differentiated, function- ally integrated, and autonomous system. I distinguish two conceptions of development in the organisational tradition that yield two different conceptions of the organism: the life- history view claims that organisms can be considered as (...) such during their whole ontogeny; the constitutive view distinguishes two periods in the life history, a period of generation and a period of self-maintenance of a constitutive organisation. Arguing in favour of the con- stitutive view, it will be claimed that the organisational criteria for the definition of organ- ism (i.e., differentiation, functional integration, and autonomy) can only be applied to the developmental system when it has entered the period of self-maintenance of a constitutive organisation. under the light of current research in developmental biology, it is possible to make explicit how organisms come to be as organisms. To this end, I explore key onto- genetic events that help us clarify the core aspects of animal organisation and allow us to identify the developmental stage that marks the ontological transition between an organism in potency and an organism in actuality. The structure of this ontogenetic unfolding paral- lels the conceptual structure of the very notion of organism; the generation of the being of a particular organism parallels its definition. (shrink)

The question “What is an organism?”, formerly considered as essential in biology, has now been increasingly replaced by a larger question, “What is a biological individual?”. On the grounds that i) individuation is theory-dependent, and ii) physiology does not offer a theory, biologists and philosophers of biology have claimed that it is the theory of evolution by natural selection which tells us what counts as a biological individual. Here I show that one physiological field, immunology, offers a theory, which makes (...) possible a biological individuation based on physiological grounds. I give a new answer to the question of the individuation of an organism by linking together the evolutionary and the immunological approaches to biological individuation. (shrink)

Embryos start out as tiny globes, on which many important events occur, including cell divisions, shape changes and changes of neighbors, waves of contraction and expansion, motion of cell sheets, extension of filopodia, shearing of cell connections, and differentiation and morphogenesis of tissues such as skin and brain. I propose to build a robotic microscope that would enable a new way to look at embryos: Google Embryo. This is akin to sending a space probe to Jupiter and its moons, sending (...) back spectacular new visions of their complexity, activity, and beauty. (shrink)

Google Earth allows us to obtain a new vision of the planet we live on, with an ability to zoom in from space to ground level detail at any point on Earth. As it is only recently that we have been able to look toward the Earth from space, we review instead the history of imaging of the Jupiter moon Ganymede, another globe, first seen by Galileo. Observations of Ganymede are mined for lessons on the importance and impact of improving (...) imaging technology. Similarly, new insights may await us when we have proper tools for quantitatively looking at another unexplored globe, the embryo, in a sense for the first time. (shrink)

A general article discussing philosophical issues arising in connection with Aristotle's "Generation of Animals" (Chapter from Blackwell's Companion to Aristotle).

What is the evolutionary significance of the various mechanisms of imitation, emulation and social learning found in humans and other animals? This paper presents an advance in the theoretical resources for addressing that question, in the light of which standard approaches from the cultural evolution literature should be refocused. The central question is whether humans have an imitationbased inheritance system—a mechanism that has the evolutionary function of transmitting behavioural phenotypes reliably down the generations. To have the evolutionary power of an (...) inheritance system, an imitiation-based mechanism must meet a range of demanding requirements. The paper goes on to review the evidence for and against the hypothesis that there is indeed an imitation-based inheritance system in humans. (shrink)

_The Blackwell Companion to Aristotle_ provides in-depth studies of the main themes of Aristotle's thought, from art to zoology. The most comprehensive single volume survey of the life and work of Aristotle Comprised of 40 newly commissioned essays from leading experts Coves the full range of Aristotle's work, from his 'theoretical' inquiries into metaphysics, physics, psychology, and biology, to the practical and productive "sciences" such as ethics, politics, rhetoric, and art.