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Archives of 2015 in english

  1. Theoretical principles for organisms and hormones

    • M Montévil
      .
    • en
    • Séminaire Laboratoire : Evolution des Régulations Endocriniennes
    • MNHN, Paris, France

    In this presentation we will discuss three theoretical principles for biology: the principle of organization, the principle of variation and the default state of cells. We will propose possible applications to understand hormone action.

  2. In search of principles for a Theory of Organisms

    In search of principles for a Theory of Organisms

    Journal of biosciences


    Lacking an operational theory to understand life cycles hinders progress in biology. We discuss elements towards such a theory, such as inertia and thermodynamics.

    Abstract

    Lacking an operational theory to explain the organization and behaviour of matter in unicellular and multicellular organisms hinders progress in biology. Such a theory should address life cycles from ontogenesis to death. This theory would complement the theory of evolution that addresses phylogenesis, and would posit theoretical extensions to accepted physical principles and default states in order to grasp the living state of matter and define proper biological observables. Thus, we favour adopting the default state implicit in Darwin’s theory, namely, cell proliferation with variation plus motility, and a framing principle, namely, life phenomena manifest themselves as non-identical iterations of morphogenetic processes. From this perspective, organisms become a consequence of the inherent variability generated by proliferation, motility and self-organization. Morphogenesis would then be the result of the default state plus physical constraints, like gravity, and those present in living organisms, like muscular tension.

    Keywords: Animals, Biological Evolution, Biophysics/methods, Cell Division, Mice, Models, Morphogenesis, Thermodynamics

    Citation
    Longo, Giuseppe, Mael Montevil, Carlos Sonnenschein, and Ana M. Soto. 2015. “In Search of Principles for a Theory of Organisms.” Journal of Biosciences 40 (5): 955–68. https://doi.org/10.1007/s12038-015-9574-9
    Manuscript Citation Publisher Full text
  3. A novel framing principle for biology.


    Biophysical approaches to biological phenomena have provided fruitful insights, yet they generally suffer from the direct transposition of physical paradigms and methods in biology, without the deep justifications that exist in physics (as for the conservation of energy for example). In this context…

  4. From levels of organization to the organization of levels


    We propose a theoretical and formal way to account for the various levels of organization that biological systems may realize. Our key assumption is that levels of organization are to be understood as specific networks of interdependences among the functional constituents. More precisely, we will rely…

  5. Biological variability and physico-mathematical reasoning

    • M Montévil
      .
    • en
    • Workshop on approaches to variation and stability in contemporary biology
    • University of Sydney, Australia

    In this presentation, we will contrast the articulation between mathematics and phenomena that is performed in physical theorizing with the situation in biology.short, physical theorizing is grounded on stable mathematical structures, defined by theoretical symmetries and corresponding conservation…

  6. Biological organisation as closure of constraints

    Biological organisation as closure of constraints

    Journal of Theoretical Biology


    We characterize biological organization as a closure of constraints, where constraints are defined at a given time scale and are interdependent.

    Abstract

    We propose a conceptual and formal characterisation of biological organisation as a closure of constraints. We first establish a distinction between two causal regimes at work in biological systems: processes, which refer to the whole set of changes occurring in non-equilibrium open thermodynamic conditions; and constraints, those entities which, while acting upon the processes, exhibit some form of conservation (symmetry) at the relevant time scales. We then argue that, in biological systems, constraints realise closure, i.e. mutual dependence such that they both depend on and contribute to maintaining each other. With this characterisation in hand, we discuss how organisational closure can provide an operational tool for marking the boundaries between interacting biological systems. We conclude by focusing on the original conception of the relationship between stability and variation which emerges from this framework.

    Keywords: Biological organisation, Closure, Constraints, Symmetries, Time scales

    Citation
    Montévil, Maël, and Matteo Mossio. 2015. “Biological Organisation as Closure of Constraints.” Journal of Theoretical Biology 372 (May): 179–91. https://doi.org/10.1016/j.jtbi.2015.02.029
    Manuscript Citation Publisher Full text
  7. Theoretical principles for biology: organization and variation


    We argue that a theory of biological systems should rely on organization and variation as fundamental theoretical principles. Biological systems are organized natural systems that undergo functional variation. In this presentation we will provide a specific characterization of each principle while …