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)

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)

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)

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)

“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 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)

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

The aim of this paper is to evaluate the level of gender bias in Aristotle’s Generation of Animals while exercising due care in the analysis of its arguments. I argue that while the GA theory is clearly sexist, the traditional interpretation fails to diagnose the problem correctly. The traditional interpretation focuses on three main sources of evidence: (1) Aristotle’s claim that the female is, as it were, a “disabled” (πεπηρωμένον) male; (2) the claim at GA IV.3, 767b6-8 that females are (...) a departure from the kind; and (3) Aristotle’s supposed claim at GA IV.3, 768a21-8 that the most ideal outcome of reproduction is a male offspring that perfectly resembles its father. I argue that each of these passages has either been misunderstood or misrepresented by commentators. In none of these places is Aristotle suggesting that females are imperfect members of the species or that they result from the failure to achieve some teleological goal. I defend the view that the GA does not see reproduction as occurring for the sake of producing males; rather, what sex an embryo happens to become is determined entirely by non-teleological forces operating through material necessity. This interpretation is consistent with Aristotle’s view in GA II.5 that females have the same soul as the male (741a7) as well as the argument in Metaphysics X.9 that sexual difference is not part of the species form but is an affection (πάθος) arising from the matter (1058b21-4). While the traditional interpretation has tended to exaggerate the level of sexism in Aristotle’s
developmental biology, the GA is by no means free of gender bias as some recent scholarship has claimed. In the final section of the paper I point to one passage where Aristotle clearly falls back on sexist assumptions in order to answer the difficult question, “Why are animals divided into sexes?”. I argue that this passage in particular poses a serious challenge
to anyone attempting to absolve Aristotle’s developmental biology of the charge of sexism. (shrink)

Background: One of the all-time questions in evolutionary biology regards the evolution of organismal shapes, and in particular why certain forms appear repeatedly in the history of life, others only seldom and still others not at all. Recent research in this field has deployed the conceptual framework of constraints and natural selection as measured by quantitative genetic methods. Scope: In this paper I argue that quantitative genetics can by necessity only provide us with useful statistical sum- maries that may lead (...) researchers to formulate testable causal hypotheses, but that any inferential attempt beyond this is unreasonable. Instead, I suggest that thinking in terms of coordinates in phenotypic spaces, and approaching the problem using a variety of empirical methods (seeking a consilience of evidence), is more likely to lead to solid inferences regarding the causal basis of the historical patterns that make up most of the data available on phenotypic evolution. (shrink)

In this paper I address an important question in Aristotle’s biology, What are the causal mechanisms behind the transmission of biological form? Aristotle’s answer to this question, I argue, is found in Generation of Animals Book 4 in connection with his investigation into the phenomenon of inheritance. There we are told that an organism’s reproductive material contains a set of "movements" which are derived from the various "potentials" of its nature (the internal principle of change that initiates and controls development). (...) These movements, I suggest, function as specialized vehicles for communicating the parts of the parent’s heritable form during the act of reproduction. After exploring the details of this mechanism, I then take up Aristotle’s theory of inheritance proper. At the heart of the theory are three general principles (or 'laws') that govern the interactions between the maternal and paternal movements, the outcome of which determines the pattern of inheritance for the offspring. Although this paper is primarily aimed at providing a detailed analysis of Aristotle’s account of inheritance, the results of that analysis have implications for other areas of Aristotle’s biology. One of the most interesting of these is the question of whether Aristotle’s biology is anti-evolutionary (as traditionally assumed) or whether (as I argue) it leaves room for a theory of evolution by natural selection, even if Aristotle himself never took that step. (shrink)

http://www.bibliotecadigital.unicamp.br/document/?code=vtls000363614.

Ich rekonstruiere und kritisiere Hans Drieschs Argumentation für die Behauptung, daß biologischen Prozessen nur eine substanzdualistische Ontologie der belebten Materie (Vitalismus) gerecht werden kann. Meine Diagnose lautet, daß Drieschs Argumentation zwar logisch schlüssig ist bzw. durch leichte Modifikationen in eine logisch gültige Form gebracht werden kann, aber von empirisch unbegründeten, metaphysischen Prämissen über die Möglichkeiten eines energieumwandelnden Mechanismus ausgeht.