On May 11, 2021, at 11:30.
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Abstract: The classic thermodynamic account of life describes organisms as open systems, which compensate their internal low entropy by an increased dissipation in their surroundings. An intuitive consequence of this account is that complex living systems would seem to necessarily decrease the potential for life in their environment by their increased entropy production.
Within this framework, some accounts have attempted to explain biological organisation as a manifestation of the second law and the tendency to increase entropy; others have rejected this position as reductionist and moved to an account of biological organisation in non-thermodynamic terms. However, even if thermodynamics cannnot give a full account of biological organisation, there is in all cases a thermodynamic background to biological phenomena which needs to be accounted for in an understanding of the materiality of life.
In this context, James Lovelock’s idea, according to which a planet with life could be distinguished because of a thermodynamic disequilibrium in its atmospheric composition, shifts the discussion to the planetary scale, where the presence of Life becomes the explanans of a certain thermodynamic configuration. This observation, which corresponds to the Gaïan principle according to which Life modifies its physical environment to improve and maintain its own conditions of existence, has been recently developed in a systematic way by German physicist Axel Kleidon.
From this planetary standpoint, it is Life together with its physical environment that has to be considered as the primordial open, far from equilibrium dissipative system. So, while individual organisms or complex organisations within the Earth can be described as dissipative systems if considered separately from the whole, a full thermodynamic account needs to integrate them in the planetary scale, where they might (or might not) function as part of the global material organisation that sustains a low entropy environment.
Bio: Alejandro Merlo Ote (EHU/UPV)
Tuesday, 26/05/2020 at 11:30 (online, please contact firstname.lastname@example.org)
Paper available (open access) here:
The question addressed in this talk is how multicellular systems realise functionally integrated physiological entities by organising their intercellular space.
From a perspective centred on physiology and integration, biological systems are often characterised as organised in such a way that they realise metabolic self-production and self-maintenance. The existence and activity of their components rely on the network they realise 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 organisation 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 behaviours are constrained and controlled by the system they realise. 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 organisation, these factors are insufficient to provide an understanding of how cells are physically and functionally integrated in a coherent system.
To address these issues, I present a new theoretical framework of multicellularity. The thesis is that one of the fundamental theoretical principles to understand multicellularity, which is missing or underdeveloped in current accounts, is the functional organisation of the intercellular space. From this perspective, the capability to be organised 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 specialised functions such as immunity. The extracellular matrix plays a crucial active role in this respect, together with the strategies employed by multicellular systems to exert control upon internal movement and communication. Finally, I show how the organisation of space is involved in some of the failures of multicellular organisation, such as aging and cancer.