philosophies Article Is Organization of Living Systems Explained by Probability? Naoki Sato Department of Life Sciences, University of Tokyo, Tokyo 153-8902, Japan; [email protected] Abstract: Traditionally, life has been thought improbable without assuming a special principle, such as vital power. Here, I try to understand organization of living systems in terms of a more rational and materialistic notion. I have introduced the notion of inhomogeneity, which is a novel interpretation of “negentropy”, and equivalent to “bound information”, according to the probabilistic interpretation of entropy. Free energy of metabolites is a labile inhomogeneity, whereas genetic information is a more stable inhomogeneity. Dynamic emergence can result from the conflict be- tween two inhomogeneities, one labile and another stable, just like dialectic synthesis results from the conflict between thesis and antithesis. Life is a special type of dynamic emergence, which is coupled with reproduction mediated by genetic information. Biological membrane formation is taken as an example to formulate self-organization of biological systems through dynamic emergence. This system is ultimately driven by the Sun/Earth temperature difference, and is consistent with an increase in probability in the world. If we consider all entropy production related to life, such as degradation of materials and death of organisms, and ultimately the cooling of the Sun, probability always increases with the progress of living systems. Keywords: biological membrane; entropy; inhomogeneity; life; lipid; photosynthesis; probability; self-organization 1. Introduction Citation: Sato, N. Is Organization of Life has long been a subject of continuing quests of philosophers and scientists. Living Systems Explained by From the age of ancient Greek philosophy, distinction between living beings and non- Probability? Philosophies 2021, 6, 3. living things has been an essential enigma that philosophers tried to answer. A simple https://doi.org/10.3390/philosophies and clear solution was to assume a special principle in living beings, as was introduced 6010003 by Aristotle under the notion of “psyche” or “anima” [1]. Various different kinds of anima were supposed to characterize different kinds of living beings, such as plants, Received: 29 November 2020 animals, and humans. Although Aristotle’s notion of “anima” seemed non-scientific or Accepted: 8 January 2021 pre-scientific, we might be able to consider “anima” as a principle of life rather than a Published: 12 January 2021 special force of life. In the nineteenth century, supporters of vitalism supposed a special force that drives life in cellular activity, morphogenesis, and reproduction. It was called Publisher’s Note: MDPI stays neu- either “vital force,” “Lebenskräfte,” or “Entelechie,” among others [2]. “Élan vital” of Henri tral with regard to jurisdictional clai- Bergson [3] was sometimes confused with vital force, but could have meant something ms in published maps and institutio- different [4]. Garrett [2] called recurrence of a conflict between vitalism and emergent nal affiliations. materialism “intellectual amnesia.” Various properties are used to characterize life: controlled metabolism, sensibility, self organization of cell and body structure, reproduction, autonomy, and consciousness. Copyright: © 2021 by the author. Li- These are only representatives of many qualifications of life. Mechanistic understand- censee MDPI, Basel, Switzerland. ing could be possible for some of these, such as metabolism, sensibility, reproduction, This article is an open access article and autonomy. Obviously, we cannot find a plausible explanation of consciousness in the distributed under the terms and con- current status of understanding, although efforts to naturalize consciousness continue [5]. ditions of the Creative Commons At- In addition, self-organization is a curious property of life that we cannot easily provide a tribution (CC BY) license (https:// mechanistic or materialist answer, because it is different from crystallization of minerals or creativecommons.org/licenses/by/ self-assembly of bacteriophages and ribosomes, which are stabilizing reactions that occur 4.0/). Philosophies 2021, 6, 3. https://doi.org/10.3390/philosophies6010003 https://www.mdpi.com/journal/philosophies Philosophies 2021, 6, x FOR PEER REVIEW 2 of 16 Philosophies 2021, 6, 3 2 of 16 tions that occur spontaneously. Self-organization of living beings is a dynamic process thatspontaneously. requires free Self-organization energy and information, of living beings which is awas dynamic discussed process from that the requires viewpoint free en-of “molecularergy and information, vitalism” [6]. which Apparently, was discussed it proceeds from the spontaneously, viewpoint of “molecular but it is an vitalism” important [6]. aspectApparently, of life itand proceeds a part spontaneously,of a vital process but that it is needs an important explanation. aspect In ofthe life present and a partarticle, of aI willvital discuss process self-organization that needs explanation. of living In bein the presentgs in the article, light of I will dynamic discuss emergence, self-organization which involvesof living beingsconflictin of the two light inhomogeneities of dynamic emergence, and production which involvesof emergent conflict inhomogeneity. of two inho- Themogeneities notion of and inhomogeneity production of [4] emergent is related inhomogeneity. to entropy and The information, notion of inhomogeneity but also proba- [4] bility.is related Probabilistic to entropy interpretation and information, of entrop buty also and probability. information Probabilistic [7] is used to interpretation understand lifeof entropy in terms and of inhomogeneity information [7] and is used dynamic to understand emergence. life in terms of inhomogeneity and dynamic emergence. 2. Inhomogeneity and Emergence 2. Inhomogeneity and Emergence Self-organization of living systems, such as cells, organisms, and ecosystems, is ex- plainedSelf-organization by ingestion of of “negative living systems, entropy” such by asSchrödinger cells, organisms, [8] in the and middle ecosystems, of the is20th ex- century.plained bySince ingestion then, ofvarious “negative different entropy” versio by Schrödingerns of formulation [8] in the were middle proposed, of the 20thbut cen-the essentialtury. Since point then, remained various differentidentical, versions namely, of that formulation free energy were flow proposed, into the living but the systems essential is coupledpoint remained with dissipation identical, namely,of entropy that to free the energy outer flow world. into Free the livingenergy systems is equivalent is coupled to negativewith dissipation entropy, of and entropy entropy to the increase outer world. is eq Freeuivalent energy to isrealization equivalent of to a negative more probable entropy, state.and entropy In other increase words, isself-organ equivalentization to realization of living ofsystems a more is probable part of a state. transitionIn other to a words more, self-organization of living systems is part of a transition to a more probable world. In the probable world. In the following arguments, I intend to rationalize this apparently par- following arguments, I intend to rationalize this apparently paradoxical statement by adoxical statement by presenting realistic explanation using examples based on current presenting realistic explanation using examples based on current biological knowledge. biological knowledge. I have introduced “inhomogeneity” I, which is defined as the “entropy deficit” or I have introduced “inhomogeneity” I, which is defined as the “entropy deficit” or difference between the maximum entropy Smax and the actual entropy S [4]: difference between the maximum entropy Smax and the actual entropy S [4]: I = Smax − S. (1) I = Smax − S. (1) Historically, inhomogeneity is equivalent to “bound information” of of Brillouin [9], [9], who alsoalso usedused “negentropy”“negentropy” for for what what I callI call inhomogeneity. inhomogeneity. I prefer I prefer inhomogeneity, inhomogeneity, because be- causethis term this adequatelyterm adequately describes describes the situation the situ ination which in which something something is not distributed is not distributed evenly. evenly.This is equivalent This is equivalent to the situation to the insituation which entropyin which is entropy lower than is lower the maximum than thepossible maximum en- possibletropy. The entropy. relationship The relationship between inhomogeneity between inhomogeneity and probability and is probability simply illustrated is simply in anil- lustratedexample ofin binomialan example distribution of binomial (Figure distribution1). (Figure 1). Figure 1. UnevenUneven distribution distribution is evaluated by inhomogeneity and probability. Let us consider a box with two parts, A an andd B. There is a virtual wall between the twotwo parts, parts, but but there is no real obstacleobstacle that preventsprevents movement of particles between the two parts. If ten particles are present in the box, and the particles can displace freely, Philosophies 2021, 6, 3 3 of 16 under this circumstance, we can imagine 11 different states in which part A contains different numbers of particles. The multiplicity factor W(n) of each state, or the number of different combinations of identical but distinguishable particles, can be obtained by a simple calculation: W(n) = 10!/n! (10 − n)!, (2) where n is the number of