Is defining life pointless? Operational definitions at the frontiers of Biology

Despite numerous and increasing attempts to define what life is, there is no consensus on necessary and sufficient conditions for life. Accordingly, some scholars have questioned the value of definitions of life and encouraged scientists and philosophers alike to discard the project. As an alternative to this pessimistic conclusion, we argue that critically rethinking the nature and uses of definitions can provide new insights into the epistemic roles of definitions of life for different research practices. This paper examines the possible contributions of definitions of life in scientific domains where such definitions are used most (e.g., Synthetic Biology, Origins of Life, Alife, and Astrobiology). Rather than as classificatory tools for demarcation of natural kinds, we highlight the pragmatic utility of what we call operational definitions that serve as theoretical and epistemic tools in scientific practice. In particular, we examine contexts where definitions integrate criteria for life into theoretical models that involve or enable observable operations. We show how these definitions of life play important roles in influencing research agendas and evaluating results, and we argue that to discard the project of defining life is neither sufficiently motivated, nor possible without dismissing important theoretical and practical research

Emergent processes as generation of discontinuities

In this article we analyse the problem of emergence in its diachronic dimension. In other words, we intend to deal with the generation of novelties in natural processes. Our approach aims at integrating some insights coming from Whitehead’s Philosophy of the Process with the epistemological framework developed by the “autopoietic” tradition. Our thesis is that the emergence of new entities and rules of interaction (new “fields of relatedness”) requires the development of discontinuous models of change. From this standpoint natural evolution can be conceived as a succession of emergences — each one realizing a novel “extended” present, described by distinct models — rather than as a single and continuous dynamics. This theoretical and epistemological framework is particularly suitable to the investigation of the origin of life, an emblematic example of this kind of processes

Systems, Autopoietic

Definition The authors’ definition of the autopoietic system has evolved through the years. One of them states that an autopoietic system is organized (defined as a unity) as a network of processes of production (transformation and destruction) of components that produces the components which: (1) through their interactions and transformations regenerate and realize the network of processes (relations) that produced them; and (2) constitute it (the machine) as a concrete unity in the space in which they exist by specifying the topological domain of its realization as such a network (Varela 1979, p. 13). Nearly the same formula was earlier used to define an autopoietic machine (Maturana and Varela 1973/1980, 1984/1987, p. 135

Complex emergence and the living organization: an epistemological framework for biology

In this article an epistemological framework is proposed in order to integrate the emergentist thought with systemic studies on biological autonomy, which are focused on the role of organization. Particular attention will be paid to the role of the observer’s activity, especially: (a) the different operations he performs in order to identify the pertinent elements at each descriptive level, and (b) the relationships between the different models he builds from them. According to the approach sustained here, organization will be considered as the result of a specific operation of identifi- cation of the relational properties of the functional components of a system, which do not necessarily coincide with the intrinsic properties of its structural constituents. Also, an epistemological notion of emergence—that of “complex emergence”—will be introduced, which can be defined as the insufficiency, even in principle, of a single descriptive modality to provide a complete description of certain classes of systems. This integrative framework will allow us to deal with two issues in biological and emergentist studies: (1) distinguishing the autonomy proper of living systems from some physical processes like those of structural stability and pattern generation, and (2) reconsidering the notion of downward causation not as a direct or indirect influence of the whole on its parts, but instead as an epistemological problem of interaction between descriptive domains in which the concept of organization proposed and the observational operations related to it play a crucial role

Glycemia Regulation: From Feedback Loops to Organizational Closure.

Endocrinologists apply the idea of feedback loops to explain how hormones regulate certain bodily functions such as glucose metabolism. In particular, feedback loops focus on the maintenance of the plasma concentrations of glucose within a narrow range. Here, we put forward a different, organicist perspective on the endocrine regulation of glycaemia, by relying on the pivotal concept of closure of constraints. From this perspective, biological systems are understood as organized ones, which means that they are constituted of a set of mutually dependent functional structures acting as constraints, whose maintenance depends on their reciprocal interactions. Closure refers specifically to the mutual dependence among functional constraints in an organism. We show that, when compared to feedback loops, organizational closure can generate much richer descriptions of the processes and constraints at play in the metabolism and regulation of glycaemia, by making explicit the different hierarchical orders involved. We expect that the proposed theoretical framework will open the way to the construction of original mathematical models, which would provide a better understanding of endocrine regulation from an organicist perspective

Understanding Multicellularity: The Functional Organization of the Intercellular Space

The aim of this paper is to provide a theoretical framework to understand how multicellular systems realize functionally integrated physiological entities by organizing their intercellular space. From a perspective centered on physiology and integration, biological systems are often characterized as organized in such a way that they realize metabolic self-production and self-maintenance. The existence and activity of their components rely on the network they realize and on the continuous management of the exchange of matter and energy with their environment. One of the virtues of the organismic approach focused on organization is that it can provide an understanding of how biological systems are functionally integrated into coherent wholes. Organismic frameworks have been primarily developed by focusing on unicellular life. Multicellularity, however, presents additional challenges to our understanding of biological systems, related to how cells are capable to live together in higher-order entities, in such a way that some of their features and behaviors are constrained and controlled by the system they realize. Whereas most accounts of multicellularity focus on cell differentiation and increase in size as the main elements to understand biological systems at this level of organization, we argue that these factors are insufficient to provide an understanding of how cells are physically and functionally integrated in a coherent system. In this paper, we provide a new theoretical framework to understand multicellularity, capable to overcome these issues. Our thesis is that one of the fundamental theoretical principles to understand multicellularity, which is missing or underdeveloped in current accounts, is the functional organization of the intercellular space. In our view, the capability to be organized in space plays a central role in this context, as it enables (and allows to exploit all the implications of) cell differentiation and increase in size, and even specialized functions such as immunity. We argue that the extracellular matrix plays a crucial active role in this respect, as an evolutionary ancient and specific (non-cellular) control subsystem that contributes as a key actor to the functional specification of the multicellular space and to modulate cell fate and behavior. We also analyze how multicellular systems exert control upon internal movement and communication. Finally, we show how the organization of space is involved in some of the failures of multicellular organization, such as aging and cancer

Auto-organización y autopoiesis

El prefijo “auto” en autoorganización y autopoiesis se refiere a la existencia de una identidad o agencialidad implicada en el orden, organización o producción de un sistema que se corresponde con el sistema mismo, en contraste con el diseño o la influencia de carácter externo. La autoorganización (AO) estudia la manera en la que los procesos de un sistema alcanzan de forma espontánea un orden u organización complejo, bien como una estructura o patrón emergente, bien como algún tipo de finalidad o identidad autoconstruida. En este trabajo nos ocupamos del concepto de AO en el contexto de la problemática sobre la naturaleza la vida y de los organismos vivientes. Este concepto se elabora en diferentes tradiciones científicas y filosóficas, a partir de su origen en la filosofía kantiana. La cibernética trata de emular la organización de los seres vivos y su teleología mediante la construcción de máquinas; desarrolla una perspectiva centrada en la regulación y en la causalidad mutua entre componentes del sistema. Estos trabajos, a veces complementados con la teoría de sistemas y la teoría de la información, son fundamentales para el desarrollo de la ciencia del siglo XX, especialmente las ciencias computacionales y la biología. Una segunda corriente surge desde la termodinámica de los procesos irreversibles alejados del equilibrio a partir, entre otros, de los trabajos de la escuela de Bruselas, en la que la AO se explora como la formación espontánea de estructuras de orden disipativo. Una tercera tradición, tal vez la más profundamente kantiana, se desarrolla en el contexto de la biología del desarrollo e integra a las dos mencionadas previamente, pues combina aspectos de las dos previas en el desarrollo ontogenético. Podemos decir que cada una de estas concepciones de la AO se relaciona con modelos paradigmáticos diferentes. La noción de autopoiesis (AP), por su parte, fue propuesta en los años 70 por los biólogos chilenos Humberto Maturana y Francisco Varela para explicar la organización individual de los seres vivos como un proceso dinámico que genera una identidad desde las operaciones del sistema (Maturana y Varela 1973). Puede decirse que hereda y reorganiza ideas de la tradición de la AO, especialmente la kantiana y la cibernética, para proponer una teoría biológica alternativa. El enfoque autopoiético concibe el fenómeno de la vida y a los seres vivos de forma muy diferente a la teoría de la evolución o la biología molecular que constituían las líneas de investigación predominantes en la biología de su tiempo. La teoría subraya como propiedad básica de un sistema viviente su autoconstitución dinámica como unidad dotada de identidad a partir de interacciones entre sus componentes. Sin embargo, aquellas propiedades de la vida consideradas primordiales en el enfoque darwiniano, como la reproducción o la evolución, se ven como secundarias, pues requieren de la existencia previa de sistemas autopoiéticos. El objetivo de esta voz es examinar diferentes aspectos que configuran las tradiciones autoorganizativa y autopoiética, en especial las tensiones conceptuales internas que permiten comprender los desafíos a los que se enfrentan ambas en el marco de la filosofía y la teoría de la biología, así como la forma en que sus posiciones e intuiciones contrastan con otras perspectivas en biología

La circularité biologique : concepts et modèles

National audienceThis chapter offers an overview of the theoretical and philosophical tradition that, during the last two centuries, has emphasised the central role of circularities in biological phenomena. In this tradition, organisms realise a circular causal regime insofar as their existence depends on the effects of their own activity: they determine themselves. In turn, self-determination is the grounding of several biological properties and dimensions, as individuation, teleology, normativity and functionality. We show how this general idea has been theorised sometimes through concepts, sometimes through models, and sometimes through both. We analyse the main differences between the various contributions, by emphasising their strengths and weaknesses. Lastly, we conclude by mentioning some contemporary developments, as well ass some future research directions.Ce chapitre propose un aperçu de la tradition théorique et philosophique qui, au cours des deux derniers siècles, a mis la circularité au centre de l'analyse des phénomènes biologiques. Selon cette tradition, les organismes réalisent un régime causal circulaire dans la mesure où leur existence dépend des effets de leur propre activité : les organismes biologiques s'autodéterminent. A son tour, l'autodétermination est le fondement d'un certain nombre de propriétés et dimensions biologiques, telles que l'individuation, la téléologie, la normativité ou encore la fonctionnalité. Nous montrons comment cette idée générale a fait l'objet d'une théorisation qui a pris, selon les cas, la forme d'une conceptualisation, d'une modélisation ou les deux à fois. Nous analysons les différences principales entre les différentes contributions, en soulignant leurs qualités et faiblesses. Enfin, nous concluons en évoquant certains développements contemporains de cette tradition, ainsi que quelques pistes de recherche futures