Search

The definition, origin and recreation of life remain elusive. As others have suggested, only once we put life into reductionist physical terms will we be able to solve those questions. To that end, this work proposes the phenomenon of life to be the product of two dissipative mechanisms. From them, one characterises extant biological life and deduces a testable scenario for its origin. The proposed theory of life allows its replication, reinterprets ecological evolution and creates new constraints on the search for life. [ABSTRACT FROM AUTHOR] more...

It should be the ultimate goal of any theory of evolution to delineate the contours of an integrative system to answer the question: How does life (in all its complexity) evolve (which can be called mega‐evolution)? But how to plausibly define 'life'? My answer (1994–2023) is: 'life' sounds like a noun, but denotes an activity, and thus is a verb. Life (L) denotes nothing else than the total sum (∑) of all acts of communication (transfer of information) (C) executed by any type of senders–receivers at all their levels (up to at least 15) of compartmental organization: L = ∑C. The 'communicating compartment' is better suited to serve as the universal unit of structure, function and evolution than the cell, the smallest such unit. By paying as much importance to communication activity as to the Central Dogma of molecular biology, a wealth of new insights unfold. The major ones are as follows. (1) Living compartments have not only a genetic memory (DNA), but also a still enigmatic cognitive and an electrical memory system (and thus a triple memory system). (2) Complex compartments can have up to three types of progeny: genetic descendants/children, pupils/learners and electricians. (3) Of particular importance to adaptation, any act of communication is a problem‐solving act because all messages need to be decoded. Hence through problem‐solving that precedes selection, life itself is the driving force of its own evolution (a very clever but counterintuitive and unexpected logical deduction). Perhaps, this is the 'vital force' philosopher and Nobel laureate (in 1927) Henri Bergson searched for but did not find. [ABSTRACT FROM AUTHOR] more...

Simple Summary: The state of 'being alive' is difficult to characterize because 'life' is currently defined using superficial features or long-term processes, rather than a single physical property unique to living things. For instance, biological molecules exhibit a vast range of structures and attributes, and a shared property is elusive. However, current knowledge suggests that key biomolecules governing a range of fundamental processes within cells do share one specific characteristic: all respond to energy absorption and dissipation by changing conformation and thus physical shape along one plane. Cyclic, repeated uniplanar shape changes induce unidirectional motion (linear or rotational movement) in molecules and the processes they govern, which is the basis of mechanistic activity and work within cells. In contrast, molecules in non-living systems do not change conformation in a way that performs work. The premise of energy conversion into directed motion suggests that life is a process whereby self-governing networks of molecular 'heat engines' create structure, whereas non-living structures are created and maintained by non-heat engine processes. A definition of life based on autonomous heat engine networks does not depend on any specific type of molecule or chemical process, and is potentially applicable to chemical environments different from those on Earth. The multifarious internal workings of organisms are difficult to reconcile with a single feature defining a state of 'being alive'. Indeed, definitions of life rely on emergent properties (growth, capacity to evolve, agency) only symptomatic of intrinsic functioning. Empirical studies demonstrate that biomolecules including ratcheting or rotating enzymes and ribozymes undergo repetitive conformation state changes driven either directly or indirectly by thermodynamic gradients. They exhibit disparate structures, but govern processes relying on directional physical motion (DNA transcription, translation, cytoskeleton transport) and share the principle of repetitive uniplanar conformation changes driven by thermodynamic gradients, producing dependable unidirectional motion: 'heat engines' exploiting thermodynamic disequilibria to perform work. Recognition that disparate biological molecules demonstrate conformation state changes involving directional motion, working in self-regulating networks, allows a mechanistic definition: life is a self-regulating process whereby matter undergoes cyclic, uniplanar conformation state changes that convert thermodynamic disequilibria into directed motion, performing work that locally reduces entropy. 'Living things' are structures including an autonomous network of units exploiting thermodynamic gradients to drive uniplanar conformation state changes that perform work. These principles are independent of any specific chemical environment, and can be applied to other biospheres. [ABSTRACT FROM AUTHOR] more...

Discussions on the status of definitions of life have long been dominated by a position known as definitional pessimism. Per the definitional pessimist, there is no point in trying to define life. This claim is defended in different ways, but one of the shared assumptions of all definitional pessimists is that our attempts to define life are attempts to provide a list of all necessary and sufficient conditions for something to count as alive. In other words, a definition of life is a strict, descriptive definition. Against this, several pragmatic alternatives have been put forward. On these pragmatic accounts, definitions of life are not strictly, but rather loosely descriptive. Their purpose is not to be true, but to be useful to scientists by guiding scientific practice. More recently, this position has come under attack for not being able to explain how our attempts to define life are connected to scientific progress within the biological sciences. Here, I argue to the contrary by showing how pragmatic definitions of life can be, and in fact are, conducive to scientific progress. Additionally, I show how the pragmatic account of definitions of life can be brought to bear upon our normative discussions involving definitions of life. [ABSTRACT FROM AUTHOR] more...

The phenomenon of life belongs to the most intriguing and puzzling aspects of reality, studied in various divisions of natural science, as well as in philosophy and theology. The purpose of this article is twofold. Firstly, it aims at bringing into the rich contemporary conversation on the nature, origin, and persistence of life a deeper and more thorough insight coming from the classical Aristotelian-Thomistic philosophy of nature and metaphysics. Secondly, in reference to the theological aspects of the debate, the article presents the two contrasting positions on the necessity of a direct divine intervention in the origin of life and analyzes them from the same Aristotelian-Thomistic perspective. [ABSTRACT FROM AUTHOR] more...

There are about 100 different contradictory definitions of life. The definition of life based on symbiosis that is presented here differs fundamentally from them; it gives life a value. So this definition offers a basis for ethical and legal action e.g. in organ transplants. It is based on principles and is not an ad hoc model: Significant processes for life are basis for a theoretical concept. Quality criteria for definitions are employed to control the concept. There is a graduation, not a clear division, between inanimate and animate. The graduation is based on the amount of symbiosis to be found. Life is based on symbiosis. The ideas of “ethics” and “reality” are considered in the context of this definition. more...

The question of the origin of life is a tenacious question that challenges many branches of science but is also extremely multifaceted. While prebiotic chemistry and micropaleontology reformulate the question as that of explaining the appearance of life on Earth in the deep past, systems chemistry and synthetic biology typically understand the question as that of demonstrating the synthesis of novel living matter from nonliving matter independently of historical constraints. The objective of this contribution is to disentangle the different readings of the origin-of-life question found in science. We identify three main dimensions along which the question can be differently constrained depending on context: historical adequacy, natural spontaneity, and similarity to life-as-we-know-it. We argue that the epistemic status of what needs to be explained—the explanandum—varies from approximately true when the origin-of-life question is the most constrained to entirely speculative when the constraints are the most relaxed. This difference in epistemic status triggers a shift in the nature of the origin-of-life question from an explanation-seeking question in the most constrained case to a fact-establishing question in the lesser-constrained ones. We furthermore explore how answers to some interpretations of the origin-of-life questions matter for other interpretations. [ABSTRACT FROM AUTHOR] more...

This is a digest of how various researchers in biology and astrobiology have explored questions of what defines living organisms—definitions based on functions or structures observed in organisms, or on systems terms, or on mathematical conceptions like closure, chirality, quantum mechanics and thermodynamics, or on biosemiotics, or on Darwinian evolution—to clarify the field and make it easier for endeavors in artificial intelligence to make progress. Current ideas are described to promote work between astrobiologists and computer scientists, each concerned with living organisms. A four-parameter framework is presented as a scaffold that is later developed into what machines lack to be considered alive: systems, evolution, energy and consciousness, and includes Jagers operators and the idea of dual closure. A novel definition of consciousness is developed which describes mental objects both with and without communicable properties, and this helps to clarify how consciousness in machines may be studied as an emergent process related to choice functions in systems. A perspective on how quantization, acting on nucleic acids, sets up natural limits to system behavior is offered as a partial address to the problem of biogenesis. [ABSTRACT FROM AUTHOR] more...

Abstract Background The ability to self-sustain is one of the essential properties of life. However, a consistent and satisfying definition of self-sustainability is still missing. Currently, self-sustainability refers to either “no-intervention by a higher entity” or “regeneration of all the system’s components”. How to connect self-sustainability with heredity, another essential of life, is another problem, as they are often considered to be independent of each other. Last but not least, current definitions of self-sustainability failed to provide a practical method to empirically discern whether a chemical system is self-sustaining or not. Results Here I propose a definition of self-sustainability. It takes into account the chemical reaction network itself and the external environment which is simplified as a continuous-flow stirred tank reactor. One distinct property of self-sustaining systems is that the system can only proceed if molecular triggers (or called, seeds) are present initially. The molecular triggers are able to establish the whole system, indicating that they carry the preliminary heredity of the system. Consequently, life and a large group of fires (and other dissipative systems) can be distinguished. Besides, the general properties and various real-life examples of self-sustaining systems discussed here together indicate that self-sustaining systems are not uncommon. Conclusions The definition I proposed here naturally connects self-sustainability with heredity. As this definition involves the continuous-flow stirred tank reactor, it gives a simple way to empirically test whether a system is self-sustaining or not. Moreover, the general properties and various real-life examples of self-sustaining systems discussed here provide practical guidance on how to construct and detect such systems in real biology and chemistry. Reviewers This article was reviewed by Wentao Ma and David Baum. more...

During the last decades the question of defining life has gained increased interest but, at the same time, the difficulty in reaching consensus on a possible answer has led many to skeptical positions. This, in turn, has raised a wider debate about why defining life is so hard and controversial. Such a debate (or 'meta-debate') introduces additional aspects to be considered, like the role and nature of a definition of life itself. In this paper, we will focus on those aspects, arguing that progress can be made (and has, indeed, been made) if we conceive definitions of life as open heuristic tools that contribute(d) to develop specific research strategies in the biological sciences and, more generally, to increase our understanding of life's complexity. In contrast with pragmatic or operationalist approaches, we will defend that definitions of life comprise a set of ontological assumptions, together with an inherent unifying vocation, so they should be subject to comparison and critical assessment, closely related to the success or failure of the corresponding research programs, but also to the success or failure in establishing well-grounded interconnections among the latter. We consider that the search for a more coherent, integrated and generalized theory of biology cannot be pursued without keeping an empirical standpoint, and the exercise of defining life should not be taken as an obstacle but as a valuable (and, of course, evaluable) instrument to achieve that goal. [ABSTRACT FROM AUTHOR] more...

Ervin Bauer (1890–1938) made historical contributions to contemporary biology, provided a new definition of life, defined the contents of theoretical biology. He worked in different countries, perturbed by deep historical events. These historical events necessarily impacted his fate and finally led to the violent loss of his life and the life of his wife. His work and with it his theory of life had a no less complicated history than the history of his personal life. Bauer's main work "Theoretical Biology" was published in 1935 in Russian. The author and his wife Stefánia became victims of the Great Purge. They were executed in 1938, all their publications were banned and most copies of "Theoretical Biology" destroyed. Ervin and Stefánia Bauer were rehabilitated in 1956 but renewed publication of Bauer's works was delayed. The first reprint edition of "Theoretical Biology" of 1967 was not in Russian, but was a translation into Hungarian, the native language of Bauer. The first Russian reprint of "Theoretical Biology", in which the original Russian chapters are followed by short English summaries, was published in Hungary in 1982. This edition was prepared by Hungarian and Russian scientists. The best-known Russian edition of "Theoretical Biology" was published in 2002 in St. Petersburg. A complete English translation of Bauer's main work "Theoretical Biology" is still outstanding. [ABSTRACT FROM AUTHOR] more...

Here we have proposed a new biological definition of life based on the function and reproduction of existing genes and creation of new ones, which is applicable to both unicellular and multicellular organisms. First, we coined a new term “genetic information metabolism” comprising functioning, reproduction, and creation of genes and their distribution among living and non-living carriers of genetic information. Encompassing this concept, life is defined as organized matter that provides genetic information metabolism. Additionally, we have articulated the general biological function of life as Tetz biological law: “General biological function of life is to provide genetic information metabolism” and formulated novel definition of life: “Life is an organized matter that provides genetic information metabolism”. New definition of life and Tetz biological law allow to distinguish in a new way living and non-living objects on Earth and other planets based on providing genetic information metabolism. more...

The concept of "life" certainly is of some use to distinguish birds and beavers from water and stones. This pragmatic usefulness has led to its construal as a categorical predicate that can sift out living entities from non-living ones depending on their possessing specific properties—reproduction, metabolism, evolvability etc. In this paper, we argue against this binary construal of life. Using text-mining methods across over 30,000 scientific articles, we defend instead a degrees-of-life view and show how these methods can contribute to experimental philosophy of science and concept explication. We apply topic-modeling algorithms to identify which specific properties are attributed to a target set of entities (bacteria, archaea, viruses, prions, plasmids, phages and the molecule of adenine). Eight major clusters of properties were identified together with their relative relevance for each target entity (two that relate to metabolism and catalysis, one to genetics, one to evolvability, one to structure, and—rather unexpectedly—three that concern interactions with the environment broadly construed). While aligning with intuitions—for instance about viruses being less alive than bacteria—these quantitative results also reveal differential degrees of performance that have so far remained elusive or overlooked. Taken together, these analyses provide a conceptual "lifeness space" that makes it possible to move away from a categorical construal of life by empirically assessing the relative lifeness of more-or-less alive entities. [ABSTRACT FROM AUTHOR] more...

The philosophy of biology is witnessing an increasing enthusiasm for what can be called "individuals thinking". Individuals thinking is a perspective on the metaphysics of biological entities according to which conceiving of them as individuals rather than kinds enables us to expose ongoing metaphysical debates as focusing on the wrong question, and to achieve better accounts of the metaphysics of biological entities. In this paper, I examine two cases of individuals thinking, the claim that species are individuals and the claim that life on Earth is an individual. I argue that these claims fail to do the metaphysical work that one would want them to do. I highlight problems with the specific claims as well as with the general notion of 'individual', and argue that naturalistic metaphysicians of biology should think of the metaphysical status of theoretical entities, such as species and life, as fundamentally theory-dependent. This implies a metaphysical pluralism, that allows that in some theories species, life, and other such entities may feature as individuals, whereas in others they may feature as kinds. [ABSTRACT FROM AUTHOR] more...

Copyright of Filozofia i Nauka is the property of Institute of Philosophy & Sociology of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Copyright of Filozofia i Nauka is the property of Institute of Philosophy & Sociology of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) more...

Highlights • The basic dogma of life author establishes as Shannonian information able to maintain itself via various cis-actions (metabolism) — the self-maintainable information. • A system of self-maintainable information that reproduces itself causing evolution is being proposed to be a phenomenon of life defined as the continuum of self-maintainable information. • A living entity is being defined as a distinct element of the self-maintainable information's continuum, while distinctness is proposed to be any process that defines boundaries of the entity. • A cell-centered position of some researchers and status of genetic parasites, software, computer viruses and potential alien life is being discussed. • A plausible mechanism of divergence of the initial pre-living entity into cells and viruses is being proposed. Abstract The quest for defining life has lasted since the beginning of modern science. During the last century, we have reached a lot of milestones toward the understanding of life and its molecular basis. Also, as living creatures, we have imprinted awareness about what is life and what is not. It seems like we have everything we need to formulate the definition of life. If so, why has one, that would satisfy everybody, not yet been announced? What is holding us back? Although we seem to know what life is, our understanding of its edges is still blurry. Therefore, author analyses Bernal's stages of biopoiesis and proposes features with Bernoulli distribution so the classification can be as clear-cut as it is possible. Subsequently, the definition of the phenomenon of life based on Shannon's Information Theory is being proposed as a Continuum of the Self-Maintainable Information; and the definition of the living entity as a Distinct Element of that Continuum. [ABSTRACT FROM AUTHOR] more...

A new definition of life is proposed and discussed in the present article. It is formulated by modifying and extending NASA's working definition of life, which postulates that life is a "self-sustaining chemical system capable of Darwinian evolution". The new definition includes a thermodynamical aspect of life as a far from equilibrium system and considers the flow of information from the environment to the living system. In our derivation of the definition of life we have assumed the hypothesis, that during the emergence of life evolution had to first involve autocatalytic systems that only subsequently acquired the capacity of genetic heredity. The new proposed definition of life is independent of the mode of evolution, regardless of whether Lamarckian or Darwinian evolution operated at the origins of life and throughout evolutionary history. The new definition of life presented herein is formulated in a minimal manner and it is general enough that it does not distinguish between individual (metabolic) network and the collective (ecological) one. The newly proposed definition of life may be of interest for astrobiology, research into the origins of life or for efforts to produce synthetic or artificial life, and it furthermore may also have implications in the cognitive and computer sciences. [ABSTRACT FROM AUTHOR] more...

The main unique features of biological systems are reviewed, and four necessary and sufficient attributes of life are formulated, based on the ideas of Ervin Bauer. The possibility of the occurrence of each of these attributes during the origin of life is analyzed. As a result, different scenarios for the origin of life are presented, with their pros and cons. Next, the mainstream of biological evolution is discussed, considering it as a special case of general complexification, and structuredness is defined as a quantitative measure of structural complexity. By introducing the concepts of post-dissipative structure and ratcheting process based on "frozen" patterns, their role in the generation of biological structures underlying biological evolution is demonstrated. Furthermore, it is proposed that all living things can be divided into micro- (unicellular) and macro- (multicellular) creatures, which differ from each other even more radically than the difference between prokaryotes and unicellular eukaryotes. Then the fifth, sufficient, but not necessary attribute of life, hierarchicality , is formulated, which is fully applicable only to macrolife. It is also shown that living organisms are primarily chemodynamic rather than thermodynamic systems, and three basic laws of biochemodynamics are formulated. Finally, fifteen basic features of living beings, grouped into four basic blocks, are summarized. [ABSTRACT FROM AUTHOR] more...

In this paper we explore the relevance and integration of system theory and thermodynamics in terms of the Earth system. It is proposed that together, these fields explain the evolution, organization, functionality and directionality of life on Earth. We begin by summarizing historical and current thinking on the definition of life itself. We then investigate the evidence for a single unit of life. Given that any definition of life and its levels of organization are intertwined, we explore how the Earth system is structured and functions from an energetic perspective, by outlining relevant thermodynamic theory relating to molecular, metabolic, cellular, individual, population, species, ecosystem and biome organization. We next investigate the fundamental relationships between systems theory and thermodynamics in terms of the Earth system, examining the key characteristics of self-assembly, self-organization (including autonomy), emergence, non-linearity, feedback and sub-optimality. Finally, we examine the relevance of systems theory and thermodynamics with reference to two specific aspects: the tempo and directionality of evolution and the directional and predictable process of ecological succession. We discuss the importance of the entropic drive in understanding altruism, multicellularity, mutualistic and antagonistic relationships and how maximum entropy production theory may explain patterns thought to evidence the intermediate disturbance hypothesis. • An novel analysis of the role of thermodynamics in system theory. • Proposal to understand mutualist/antagonist relations as thermodynamically driven. • Maximum entropy production as explanation of intermediate disturbance hypothesis. [ABSTRACT FROM AUTHOR] more...

In this paper the life phenomenon is analysed from cybernetic point of view. The Korzeniewski’s approach is discussed and complemented. The analysis is based on autonomous systems theory and information metabolism theory. Philosophical aspects of the problem are taken into consideration as well. more...

Origin of life research is one of the greatest scientific frontiers of mankind. Many hypotheses have been proposed to explain how life began. Although different hypotheses emphasize different initial phenomena, all of them agree around one important concept: at some point, along with the chain of events toward life, Darwinian evolution emerged. There is no consensus, however, how this occurred. Frequently, the mechanism leading to Darwinian evolution is not addressed and it is assumed that this problem could be solved later, with experimental proof of the hypothesis. Here, the author first defines the minimum components required for Darwinian evolution and then from this standpoint, analyzes some of the hypotheses for the origin of life. Distinctive features of Darwinian evolution and life rooted in the interaction between information and its corresponding structure/function are then reviewed. Due to the obligatory dependency of the information and structure subject to Darwinian evolution, these components must be locked in their origin. One of the most distinctive characteristics of Darwinian evolution in comparison with all other processes is the establishment of a fundamentally new level of matter capable of evolving and adapting. Therefore, the initiation of Darwinian evolution is the “point of no return” after which life begins. In summary: a definition and a mechanism for Darwinian evolution are provided together with a critical analysis of some of the hypotheses for the origin of life. more...

Most definitions of life assume that, at a minimum, life is a physical form of matter distinct from its environment at a lower state of entropy than its surroundings, using energy from the environment for internal maintenance and activity, and capable of autonomous reproduction. These assumptions cover all of life as we know it, though more exotic entities can be envisioned, including organic forms with novel biochemistries, dynamic inorganic matter, and self-replicating machines. The probability that any particular form of life will be found on another planetary body depends on the nature and history of that alien world. So the biospheres would likely be very different on a rocky planet with an ice-covered global ocean, a barren planet devoid of surface liquid, a frigid world with abundant liquid hydrocarbons, on a rogue planet independent of a host star, on a tidally locked planet, on super-Earths, or in long-lived clouds in dense atmospheres. While life at least in microbial form is probably pervasive if rare throughout the Universe, and technologically advanced life is likely much rarer, the chance that an alternative form of life, though not intelligent life, could exist and be detected within our Solar System is a distinct possibility. more...

Motivated by the need to paint a more general picture of what life is—and could be—with respect to the rest of the phenomena of the universe, we propose a new vocabulary for astrobiological research. Lyfe is defined as any system that fulfills all four processes of the living state, namely: dissipation, autocatalysis, homeostasis, and learning. Life is defined as the instance of lyfe that we are familiar with on Earth, one that uses a specific organometallic molecular toolbox to record information about its environment and achieve dynamical order by dissipating certain planetary disequilibria. This new classification system allows the astrobiological community to more clearly define the questions that propel their research—e.g., whether they are developing a historical narrative to explain the origin of life (on Earth), or a universal narrative for the emergence of lyfe, or whether they are seeking signs of life specifically, or lyfe at large across the universe. While the concept of “life as we don’t know it” is not new, the four pillars of lyfe offer a novel perspective on the living state that is indifferent to the particular components that might produce it. more...

Despite many attempts to achieve an adequate definition of living systems by means of a set of necessary and sufficient conditions, the opinion that such an enterprise is inexorably destined to fail is increasingly gaining support. However, we believe options do not just come down to either having faith in a future success or endorsing skepticism. In this paper, we aim to redirect the discussion of the problem by shifting the focus of attention from strict definitions (in terms of necessary and sufficient conditions) towards a philosophical framework that allows conceiving of living systems as a natural kind, but whereby natural kinds are not to be defined by fixed necessary and sufficient conditions. We argue for a property-cluster kind approach according to which living systems constitute a natural kind with vague boundaries, capable of changing, and whose members do not need to instantiate every property. We draw from Boyd’s homeostatic property-cluster theory and introduce two modifications, one regarding homeostatic mechanisms and another related to the scientific role of kinds. Thus, our view overcomes some difficulties of Boyd’s theory and we are able to account for the natural kindhood of living things. We also emphasize the most appealing features of our approach for specific research fields and address three objections to this sort of approach. [ABSTRACT FROM AUTHOR] more...

Highlights • Analysis of Rosen's theories with a focus on their mathematical content. • Provides links of Rosen's work with most recent research into mathematical modelling. • Possible implementations of ’closure to efficient causation’ in models are discussed. • Critical analysis of Rosen's use of category theory. Abstract The theoretical biologist Robert Rosen developed a highly original approach for investigating the question “What is life?”, the most fundamental problem of biology. Considering that Rosen made extensive use of mathematics it might seem surprising that his ideas have only rarely been implemented in mathematical models. On the one hand, Rosen propagates relational models that neglect underlying structural details of the components and focus on relationships between the elements of a biological system, according to the motto “throw away the physics, keep the organisation”. Rosen's strong rejection of mechanistic models that he implicitly associates with a strong form of reductionism might have deterred mathematical modellers from adopting his ideas for their own work. On the other hand Rosen's presentation of his modelling framework, (M , R) systems, is highly abstract which makes it hard to appreciate how this approach could be applied to concrete biological problems. In this article, both the mathematics as well as those aspects of Rosen's work are analysed that relate to his philosophical ideas. It is shown that Rosen's relational models are a particular type of mechanistic model with specific underlying assumptions rather than a fundamentally different approach that excludes mechanistic models. The strengths and weaknesses of relational models are investigated by comparison with current network biology literature. Finally, it is argued that Rosen's definition of life, “organisms are closed to efficient causation”, should be considered as a hypothesis to be tested and ideas how this postulate could be implemented in mathematical models are presented. [ABSTRACT FROM AUTHOR] more...

Our understanding of the universe has grown rapidly in recent decades. We’ve discovered evidence of water in nearby planets, discovered planets outside our solar system, mapped the genomes of thousands of organisms, and probed the very origins and limits of life. The scientific perspective of life-as-it-could-be has expanded in part by research in astrobiology, synthetic biology, and artificial life. In the face of such scientific developments, we argue there is an ever-growing need for universal biology, life-as-it-must-be, the multidisciplinary study of non-contingent aspects of life as guided by biological theory and constrained by the universe. We present three distinct but connected ways of universalizing biology—with respect to characterizing aspects of life everywhere, with respect to the explanatory scope of biological theory, and with respect to extending biological insights to the structure of nonbiological entities. For each of these, we sketch the theoretical goals and challenges, as well as give examples of current research that might be labeled universal biology. [ABSTRACT FROM AUTHOR] more...

It is undeniably very logical to first formulate an unambiguous definition of “Life” before engaging in defining the parameters instrumental to Life's evolution. Because nearly everybody assumes, erroneously in my opinion, that catching Life's essence in a single sentence is impossible, this way of thinking remained largely unexplored in evolutionary theory. Upon analyzing what exactly happens at the transition from “still alive” to “just dead,” the following definition emerged. What we call “Life” (L) is an activity. It is nothing other than the total sum (∑) of all communication acts (C) executed, at moment t, by entities organized as sender-receiver compartments: L = ∑C Such “living” entities are self-electrifying and talking ( = communicating) aggregates of fossil stardust operating in an environment heavily polluted by toxic calcium. Communication is a multifaceted, complex process that is seldom well explained in introductory textbooks of biology. Communication is instrumental to adaptation because, at the cellular level, any act of communication is in fact a problem-solving act. It can be logically deduced that not Natural Selection itself but communication/problem-solving activity preceding selection is the universal driving force of evolution. This is against what textbooks usually claim, although doubt on the status of Natural Selection as driving force has been around for long. Finally, adopting the sender-receiver with its 2 memory systems (genetic and cognitive, both with their own rules) and 2 types of progeny (”physical children” and “pupils”) as the universal unit of architecture and function of all living entities, also enables the seamless integration of cultural and organic evolution, another long-standing tough problem in evolutionary theory. Paraphrasing Theodosius Dobzhansky, the very essence of biology is: “Nothing in biology and evolutionary theory makes sense except in the light of the ability of living matter to communicate, and by doing so, to solve problems.” more...

The project “A Plurality of Lives” was funded and hosted by the Pufendorf Institute for Advanced Studies at Lund University, Sweden. The aim of the project was to better understand how a second origin of life, either in the form of a discovery of extraterrestrial life, life developed in a laboratory, or machines equipped with abilities previously only ascribed to living beings, will change how we understand and relate to life. Because of the inherently interdisciplinary nature of the project aim, the project took an interdisciplinary approach with a research group made up of 12 senior researchers representing 12 different disciplines. The project resulted in a joint volume, an international symposium, several new projects, and a network of researchers in the field, all continuing to communicate about and advance the aim of the project. more...

In this opinion piece, we discuss how to place evolution in the context of origin-of-life research. Our discussion starts with a popular definition: 'life is a self-sustained chemical system capable of undergoing Darwinian evolution'. According to this definition, the origin of life is the same as the origin of evolution: evolution is the 'end' of the origin of life. This perspective, however, has a limitation, in that the ability of evolution in and of itself is insufficient to explain the origin of life as we know it, as indicated by Spiegelman's and Lincoln and Joyce's experiments. This limitation provokes a crucial question: What conditions are required for replicating systems to evolve into life? From this perspective, the origin of life includes the emergence of life through evolution: evolution is a 'means' of the origin of life. After reviewing Eigen's pioneering work on this question, we mention our ongoing work suggesting that a key condition might be conflicting multi-level evolution. Taken together, there are thus two questions regarding the origin of life: how evolution gets started, and how evolution produces life. Evolution is, therefore, at the centre of the origin of life, where the two lines of enquiry must meet. This article is part of the themed issue 'Re-conceptualizing the origins of life'. [ABSTRACT FROM AUTHOR] more...

We see the last universal common ancestor of all living organisms, or LUCA, at the evolutionary separation of the Archaea from the Eubacteria, and before the symbiotic event believed to have led to the Eukarya. LUCA is often implicitly taken to be close to the origin of life, and sometimes this is even stated explicitly. However, LUCA already had the capacity to code for many proteins, and had some of the same bioenergetic capacities as modern organisms. An organism at the origin of life must have been vastly simpler, and this invites the question of how to define a living organism. Even if acceptance of the giant viruses as living organisms forces the definition of LUCA to be revised, it will not alter the essential point that LUCA should be regarded as a recent player in the evolution of life. [ABSTRACT FROM AUTHOR] more...

The attempt to define life has gained new momentum in the wake of novel fields such as synthetic biology, astrobiology, and artificial life. In a series of articles, Cleland, Chyba, and Machery claim that definitions of life seek to provide necessary and sufficient conditions for applying the concept of life—something that such definitions cannot, and should not do. We argue that this criticism is largely unwarranted. Cleland, Chyba, and Machery approach definitions of life as classifying devices, thereby neglecting their other epistemic roles. We identify within the discussions of the nature and origin of life three other types of definitions: theoretical, transdisciplinary, and diagnostic definitions. The primary aim of these definitions is not to distinguish life from nonlife, although they can also be used for classificatory purposes. We focus on the definitions of life within the budding field of astrobiology, paying particular attention to transdisciplinary definitions, and diagnostic definitions in the search for biosignatures from other planets. [ABSTRACT FROM AUTHOR] more...

Darwinian evolution requires a mechanism for generation of diversity in a population, and selective differences between individuals that influence reproduction. In biology, diversity is generated by mutations and selective differences arise because of the encoded functions of the sequences ( e.g., ribozymes or proteins). Here, I draw attention to a process that I will call chemical evolution, in which the diversity is generated by random chemical synthesis instead of (or in addition to) mutation, and selection acts on physicochemical properties, such as hydrolysis, photolysis, solubility, or surface binding. Chemical evolution applies to short oligonucleotides that can be generated by random polymerization, as well as by template-directed replication, and which may be too short to encode a specific function. Chemical evolution is an important stage on the pathway to life, between the stage of 'just chemistry' and the stage of full biological evolution. A mathematical model is presented here that illustrates the differences between these three stages. Chemical evolution leads to much larger differences in molecular concentrations than can be achieved by selection without replication. However, chemical evolution is not open-ended, unlike biological evolution. The ability to undergo Darwinian evolution is often considered to be a defining feature of life. Here, I argue that chemical evolution, although Darwinian, does not quite constitute life, and that a good place to put the conceptual boundary between non-life and life is between chemical and biological evolution. [ABSTRACT FROM AUTHOR] more...

In the classical “mind-body” wording, “body” is usually associated with the “mass aspect” of living entities and “mind” with the “immaterial” one. Thoughts, consciousness and soul are classified as immaterial. A most challenging question emerges: Can something that is truly immaterial, thus that in the wording of physics has no mass, exist at all? Many will answer: “No, impossible.” My answer is that it is very well possible, that no esoteric mechanisms need to be invoked, but that this possibility is inherent to 2 well established but undervalued physiological mechanisms. The first one is electrical in nature. In analogy with “genome,” “proteome” etc. “electrome” (a novel term) stands for the totality of all ionic currents of any living entity, from the cellular to the organismal level. Cellular electricity is truly vital. Death of any cell ensues at the very moment that it irreversibly (excluding regeneration) loses its ability to realize its electrical dimension. The second mechanism involves communication activity that is invariably executed by sender-receiver entities that incessantly handle information. Information itself is immaterial (= no mass). Both mechanisms are instrumental to the functioning of all cells, in particular to their still enigmatic cognitive memory system. Ionic/electrical currents associated with the cytoskeleton likely play a key role but have been largely overlooked. This paper aims at initiating a discussion platform from which students with different backgrounds but all interested in the immaterial dimension of life could engage in elaborating an integrating vocabulary and in initiating experimental approaches. more...

The text analyzes the problem of the multiple realization of the conditions for natural selection: variation, reproduction and heredity. The main emphasis is placed on the third of these characteristics. The main objective of the analysis is to show that a capacity for multiple realization would exist even if we omit the arguments based on astrobiology and artificial life and focus solely on the analysis of the genetics of known forms of life. The text also discusses the implications of the multiple realizability thesis for such issues as: reductionism in biology, definition of life, research on epigenetics and the autonomy of biology. The importance of multiple realization for the study of the levels of selection and the major transitions in evolution is also highlighted. [ABSTRACT FROM AUTHOR] more...

RNA played a central role in the emergence of the first life-like system on primitive Earth since RNA molecules contain both genetic information and catalytic activity. However, there are several drawbacks regarding the RNA world hypothesis. Here, I briefly discuss the feasibility of the RNA world hypothesis to deduce the RNA functions that are essential for forming a life-like system. At the same time, I have conducted a conceptual analysis of the characteristics of biosystems as a useful approach to deduce a realistic life-like system in relation to the definition of life. For instance, an RNA-based life-like system should possess enough stability to resist environmental perturbations, by developing a cell-like compartment, for instance. Here, a conceptual viewpoint is summarized to provide a realistic life-like system that is compatible with the primitive Earth environment and the capabilities of RNA molecules. According to the empirical and conceptual analysis, I propose the hypothesis that the first life-like system could have initiated from only two genes. [ABSTRACT FROM AUTHOR] more...

In the classical "mind-body" wording, "body" is usually associated with the "mass aspect" of living entities and "mind" with the "immaterial" one. Thoughts, consciousness and soul are classified as immaterial. A most challenging question emerges: Can something that is truly immaterial, thus that in the wording of physics has no mass, exist at all? Many will answer: "No, impossible." My answer is that it is very well possible, that no esoteric mechanisms need to be invoked, but that this possibility is inherent to 2 well established but undervalued physiological mechanisms. The first one is electrical in nature. In analogy with "genome," "proteome" etc. "electrome" (a novel term) stands for the totality of all ionic currents of any living entity, from the cellular to the organismal level. Cellular electricity is truly vital. Death of any cell ensues at the very moment that it irreversibly (excluding regeneration) loses its ability to realize its electrical dimension. The second mechanism involves communication activity that is invariably executed by sender-receiver entities that incessantly handle information. Information itself is immaterial (D no mass). Both mechanisms are instrumental to the functioning of all cells, in particular to their still enigmatic cognitive memory system. Ionic/electrical currents associated with the cytoskeleton likely play a key role but have been largely overlooked. This paper aims at initiating a discussion platform from which students with different backgrounds but all interested in the immaterial dimension of life could engage in elaborating an integrating vocabulary and in initiating experimental approaches. [ABSTRACT FROM AUTHOR] more...

Darwin's theory of evolution with focus on the origin of new species was formulated in an era in which the principles of genetics, biochemistry, physiology, communication etc. were not an issue. Numerous revolutionary new insights have since been gained. 1. The 'sender-receiver communicating compartment", a classical but still valuable concept, is better suited than 'the cell' to serve the role of universal unit of structure and function, 'the cell' being the smallest such unit; 2. Not only genetic, but non-genetic mechanisms as well contribute to variability that can be passed onto the next generation; 3. Natural selection, the almost unanimously accepted universal driving force of evolution, is itself the result of preceding problem-solving activity enabled by the principles of communication; 4. A logically deduced, unambiguous definition of 'Life' has been published so that now the key question can shift from Darwin's formulation towards "How does 'Life', with its many aspects, change in the course of time"? Communication activity represents the very heart of being alive, thus of 'Life itself'. In digital-era wording, living entities are hardware-software double continua. This paper advances an easily teachable change in paradigm, namely that evolution concerns ever changing complexes of signalling pathways, chemical and other, that occasionally yield both new species and additional (at least 16) levels of communication. This approach complements the genetic basis of the New Synthesis with several as yet undervalued mechanisms from physiology and development. In particular, 'the universal selfgenerated electrical dimension of cells' and Lamarckism deserve an upgrade. [ABSTRACT FROM AUTHOR] more...

Gánti׳s chemoton model of the minimal chemical organization of living systems and life criteria for the living state and a living world are characterized. It is argued that these are better interpreted as part of a heuristic pursuit of an exact theoretical biology than as a “definition of life.” Several problems with efforts to define life are discussed. Clarifying the proper use of Gánti׳s ideas to serve constructive engineering idealizations helps to show their enduring value. [ABSTRACT FROM AUTHOR] more...

I present a model for the evolution of the genetic code that seems to predict, in a totally natural way, the origin of the first mRNAs. In particular, the model-bestowing to peptidated-RNAs the major catalytic role in the phase that triggered the genetic code origin-suggests that interactions between peptidated-RNAs led to the synthesis of these ancestral catalysts. Within every group of these interactions, a pre-mRNA molecule evolved that was able to direct all interactions between peptidated-RNAs of that particular group. This represented an improvement in the coding of these interactions compared to the interaction groups that did not evolve these pre-mRNAs. This would represent a natural and intrinsic tendency. Therefore, these molecules of pre-mRNAs were positively selected because they improved the synthesis of the catalysts through this first form of coding of interactions among peptidated-RNAs. Thus, according to the model were the pairings-involving a base number greater than three (ennuplet code)-between peptidated-RNAs and pre-mRNAs that would represent the first form of the genetic code. The evolution of this ennuplet code to the triplet code might have been simply triggered by the natural tendency to make the reading module-that is the interactions between peptidated-RNAs and pre-mRNAs-of the different ennuplets to the triplet uniform, because in this way the heterogeneity existing in interactions between the aminoacylated or peptidated-RNAs and pre-mRNAs was eliminated. That is to say, there might have been the natural tendency toward the triplets because these would have made these interactions more efficient, given that the ennuplets were at least more cumbersome and therefore less economic and with an inferior adaptive value; and also because the triplets would represent the simpler choice among that available given that the doublets would have codified too few meanings and quartets instead too many. Therefore, the genetic code would result from a very long era of interactions among peptidated-RNAs under the continuous and fundamental selective pressure for improving catalysts' syntheses and thus catalysis. The model is strongly corroborated by the explanation that the tmRNA molecule (transfer-messenger RNA) would seem to be the very molecule of pre-mRNAs that the model predicts. In other words, the tmRNA would be the molecular fossil of the evolutionary stages that led to the appearance of the first mRNAs. [ABSTRACT FROM AUTHOR] more...