Cybernetic formulation of the definition of life

A definition of life (a living individual) in cybernetic terms is proposed. In this formulation, life (a living individual) is defined as a network of inferior negative feedbacks (regulatory mechanisms) subordinated to (being at service of) a superior positive feedback (potential of expansion). It is suggested that this definition is the minimal definition, necessary and sufficient, for life to be distinguished from inanimate phenomena and, as such, it describes the essence of life. Subsequently, a quantitative expression for the amount of the biologically relevant ("purposeful") information (as opposed to the amount of information in the thermodynamic sense) is proposed. This is followed by the application of the formulated approach to different phenomena of a dubious status existing presently on the Earth as well as to the process of origination of life on our planet.     

Complexity versus Uncertainty: The Question of Staying Alive

Some real objects show a very particular tendency: that of becomingindependent with regard to the uncertainty of their surroundings. This isachieved by the exchange of three quantities: matter, energy andinformation. A conceptual framework, based on both Non-equilibriumThermodynamic and the Mathematical Theory of Communication is proposedin order to review the concept of change in living individuals. Three mainsituations are discussed in this context: passive independence inconnection with resistant living forms (such as seeds, spores, hibernation,...), active independence in connection with the life span of aliving individual (whether an ant or an ant farm), and the newindependence in connection with the general debate of biological evolution.     

An Open Question on the Origin of Life: The First Forms of Metabolism

The general framework of the origin of life on Earth is outlined, emphasizing that the so‐called prebiotic ‘RNA world’ is as yet on shaky scientific ground, and that one should any way ask the question of the structure of the first protocellular compartments capable of the initial forms of metabolism. This question is the basis of the research project on the minimal cells, containing the minimal and sufficient complexity capable of leading to life. Such research is briefly summarized, highlighting experiments with liposome‐based semisynthetic cells which are capable of ribosomal protein synthesis with a very minimal number of enzymes. The most recent finding in this area of research is the unexpected observation that the formation and closure of liposomes in situ acts as an attractor for the solute molecules in solution, bringing about a very high local concentration in some of the liposomes. It is argued that this spontaneous overcrowding, which permits reactions which are not possible in the original dilute solution, might be the origin of cellular metabolism for the origin of life on Earth.     

Life on Jupiter?

The possibilities of life on Jupiter are discussed from the point view of life as we know it. That is, we assume that any life on Jupiter would not involve new principles foreign to us. Proteins would be a constituent as would fats and the other building blocks of living organisms on Earth. This leads us to a set of limiting parameters, such as pressure. Studies in the laboratory have shown that proteins and other essential molecules are denatured by pressures of 4000 atm and higher. Thus, we must not expect life in the great depths of the Jovian atmosphere. It could exist only at depths of several hundred kilometers in the atmosphere. Since no solid surface could possibly exist at such altitudes, any organisms present must be small enough to be buoyed up by the turbulent atmospheric currents or must fly or both. Such possibilities, however, seem to be real. The necessary nutrients to preserve life and foster growth could be furnished by the Miller-Urey type reactions of lonizing radiation on the reducing atmosphere undoubtedly present. There can, of course, be no possibility of oxygen on Jupiter, and so the life forms, if they exist, must be anaerobic. Such possibilities are real and have often been cited in connection with the origin of life on Earth.     

Towards a General Definition of Life

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.

     

A Universal Definition of Life: Autonomy and Open-Ended Evolution

Life is a complex phenomenon that not only requires individual self-producing and self-sustaining systems but also a historical-collective organization of those individual systems, which brings about characteristic evolutionary dynamics. On these lines, we propose to define universally living beings as autonomous systems with open-ended evolution capacities, and we claim that all such systems must have a semi-permeable active boundary (membrane), an energy transduction apparatus (set of energy currencies) and, at least, two types of functionally interdependent macromolecular components (catalysts and records). The latter is required to articulate a 'phenotype-genotype' decoupling that leads to a scenario where the global network of autonomous systems allows for an open-ended increase in the complexity of the individual agents. Thus, the basic-individual organization of biological systems depends critically on being instructed by patterns (informational records) whose generation and reliable transmission cannot be explained but take into account the complete historical network of relationships among those systems. We conclude that a proper definition of life should consider both levels, individual and collective: living systems cannot be fully constituted without being part of the evolutionary process of a whole ecosystem. Finally, we also discuss a few practical implications of the definition for different programs of research.     

The unbearable heaviness of being Kri: house construction and ethnolinguistic transformation in upland Laos

Kri people in central Laos traditionally engage in ‘heavy’ practices, including a stipulation that houses must be relocated and the flooring discarded upon a death in the family. Such ‘heavy’ practices are considered ‘real Kri’, and they are not adhered to by those who identify as Kri Phòòngq. This article examines the adoption of more enduring housing construction among the Kri, and the dynamics of ethnic identity implied by the dilemmas raised for individuals and families who must choose between (a) maintaining the heavy life of real Kri, (b) innovating new and less heavy solutions, or (c) changing identity entirely.     

Bionics, Biological Systems and the Principle of Optimal Design

The living world is an exciting and inexhaustible source of high performance solutions to the multitude of biological problems, which were attained as a result of a natural selection, during the millions and millions years evolution of life on Earth. This work presents and comments some examples of high performances of living beings, in the light of the universal principle governing the realm of living matter: Optimal Design Principle. At the same time, the transfer of these optimal solutions, from living matter to the technologies, is also discussed. This transfer is offering new and fertile perspectives to future technologies, which must be more efficient, cheaper and in perfect harmony with the biosphere.     

Defining life from death: Problems with the somatic integration definition of life

To determine when the life of a human organism begins, Mark T. Brown has developed the somatic integration definition of life. Derived from diagnostic criteria for human death, Brown’s account requires the presence of a life-regulation internal control system for an entity to be considered a living organism. According to Brown, the earliest point at which a developing human could satisfy this requirement is at the beginning of the fetal stage, and so the embryo is not regarded as a living human organism. This, Brown claims, has significant bioethical implications for both abortion and embryo experimentation. Here, we dispute the cogency of Brown’s derivation. Diagnostic criteria for death are used to determine when an organism irreversibly ceases functioning as an integrated whole, and may vary significantly depending on how developed the organism is. Brown’s definition is derived from a specific definition of death applicable to postnatal human beings, which is insufficient for generating a general definition for human organismal life. We have also examined the bioethical implications of Brown’s view, and have concluded that they are not as significant as he believes. Whether the embryo is classified as a human organism is of peripheral interest—a far more morally relevant question is whether the embryo is a biological individual with an identity that is capable of persisting during development.     

Post-Hoc Pattern-Oriented Testing and Tuning of an Existing Large Model: Lessons from the Field Vole

Pattern-oriented modeling (POM) is a general strategy for modeling complex systems. In POM, multiple patterns observed at different scales and hierarchical levels are used to optimize model structure, to test and select sub-models of key processes, and for calibration. So far, POM has been used for developing new models and for models of low to moderate complexity. It remains unclear, though, whether the basic idea of POM to utilize multiple patterns, could also be used to test and possibly develop existing and established models of high complexity. Here, we use POM to test, calibrate, and further develop an existing agent-based model of the field vole (Microtus agrestis), which was developed and tested within the ALMaSS framework. This framework is complex because it includes a high-resolution representation of the landscape and its dynamics, of the individual’s behavior, and of the interaction between landscape and individual behavior. Results of fitting to the range of patterns chosen were generally very good, but the procedure required to achieve this was long and complicated. To obtain good correspondence between model and the real world it was often necessary to model the real world environment closely. We therefore conclude that post-hoc POM is a useful and viable way to test a highly complex simulation model, but also warn against the dangers of over-fitting to real world patterns that lack details in their explanatory driving factors. To overcome some of these obstacles we suggest the adoption of open-science and open-source approaches to ecological simulation modeling.     

A guide to practical babooning: Historical,social, and cognitive contingency

As ecologically adaptable animals, baboons are distributed widely across Africa, and display a variety of morphological and behavioral differences that reflect both local ecology and a complex evolutionary history. As long‐lived, slowly reproducing animals, baboons face numerous ecological challenges to survival and successful reproduction. As group‐living animals, the social world presents an equally diverse array of challenges that require the negotiation of individual needs within the constraints imposed by others. Understanding how all these facets of baboon evolutionary history, life history, ecology, sociality, and cognition fit together is an enormous but engaging challenge, and despite one hundred years of study, it is clear there is a still much to learn about the various natural histories of baboons. What also is clear, however, is that an appreciation of contingency holds the key to understanding all these facets of baboon evolution and behavior. In what follows, I hope to illustrate exactly what I mean by this, highlighting along the way that history is not to be ignored, variability is information and not merely “noise”, and that behavioral and cognitive complexity can be two very different things.     

The genetic code and the origin of life

The problem of the origin of life understandably counts as one of the most exciting questions in the natural sciences, but in spite of almost endless speculation on this subject, it is still far from its final solution. The complexity of the functional correlation between recent nucleic acids and proteins can e.g. give rise to the assumption that the genetic code (and life) could not originate on the Earth. It was Portelli (1975) who published the hypothesis that the genetic code could not originate during the history of the Earth. In his opinion the recent genetic code represents the informational message transmitted by living systems of the previous cycle of the Universe. Here however, we defend the existence of a certain strategy in the syntheses of the genetic code during the history of the Earth. The strategy of correlation between amino acid and nucleotide polymers made an increasing velocity of the chemical evolution possible, that is, it increased the velocity of formation of the genetic code. Thus, life with the recent genetic code could originate on the Earth within the present cycle of the Universe.Present address: Institute for Pharmacy and Biochemistry, 533 51 Pardubice, Czechoslovakia.     

Origins for Everyone

The origin of life on Earth remains a mystery, but the question can still be approached with scientific rigor. Identifying life??s origins requires the definition of life itself, which has been described as a self-sustaining system capable of Darwinian evolution, although it's also possible that there is no good scientific definition. All known living systems contain linear strings of information based on DNA, a molecule that makes Darwinian evolution possible through replication and mutation. This review explains the scientific concepts and issues underlying the origin of life, possible mechanisms of origins, and the features of living systems that can arguably be viewed as an inevitable consequence of the earliest molecules.     

城市生态系统灵敏度模型评述

系统复杂性是困扰城市生态系统研究和管理的因素之一,成熟的系统分析模型可以帮助研究者及管理者应对这种挑战。德国系统思想大师Vester教授开发的灵敏度模型就是致力于解决城市规划管理中的复杂性问题,并在一系列的实践应用中取得了显著成效。网状思维(Networked Thinking)与生物控制论观点是Vester教授的核心思想,也是灵敏度模型的思想基础。模型主要分为三大层次:最底层是以数据的收集与筛选过程为代表的信息组织层次;随后是系统解释层次,主要是对系统关系网进行控制论解释;最后是系统综合评价层次,采用生物控制论观点对系统结构、行为等进行检验与评价。为方便用户使用,模型被分解为9个标准步骤,每一部分都包含数个实用的数学分析工具。模型还明确提出了4个等级的系统控制论指标(或特征)体系,以帮助使用者更好地进行系统思考。灵敏度模型本身具有众多的原创性贡献,但同时也有一定的局限性。这些经验与教训为未来的城市生态系统建模工作提供了宝贵启示。     

Did life originate from a global chemical reactor?

Many decades of experimental and theoretical research on the origin of life have yielded important discoveries regarding the chemical and physical conditions under which organic compounds can be synthesized and polymerized. However, such conditions often seem mutually exclusive, because they are rarely encountered in a single environmental setting. As such, no convincing models explain how living cells formed from abiotic constituents. Here, we propose a new approach that considers the origin of life within the global context of the Hadean Earth. We review previous ideas and synthesize them in four central hypotheses: (i) Multiple microenvironments contributed to the building blocks of life, and these niches were not necessarily inhabitable by the first organisms; (ii) Mineral catalysts were the backbone of prebiotic reaction networks that led to modern metabolism; (iii) Multiple local and global transport processes were essential for linking reactions occurring in separate locations; (iv) Global diversity and local selection of reactants and products provided mechanisms for the generation of most of the diverse building blocks necessary for life. We conclude that no single environmental setting can offer enough chemical and physical diversity for life to originate. Instead, any plausible model for the origin of life must acknowledge the geological complexity and diversity of the Hadean Earth. Future research may therefore benefit from identifying further linkages between organic precursors, minerals, and fluids in various environmental contexts.     

Understandings of climate change articulated by Swedish secondary school students

This study investigated beliefs about climate change among Swedish secondary school students at the end of their K-12 education. An embedded mixed method approach was used to analyse 51 secondary school students’ written responses to two questions: (1) What implies climate change? (2) What affects climate? A quantitative analysis of the responses revealed that ‘Earth’, ‘human’ and ‘greenhouse effect’ were frequent topics regarding the first question, and ‘pollution’, ‘atmosphere’ and ‘Earth’ were frequent regarding the second. A qualitative analysis, based on a ‘conceptual elements’ framework, focused on three elements within responses: atmosphere (causes and/or consequences), Earth (causes and consequences) and living beings (humans and/or animals and their impacts on climate change). It revealed a predominantly general or societal, rather than individual, perspective underlying students’ responses to the second question. The ability to connect general/societal issues with individual issues relating to climate change could prompt students to reflect on the contributions of individuals towards climate change mitigation, thereby constituting a basis for decision-making to promote a sustainable environment. Although the students did not discuss climate changes from an individual perspective, their statements revealed their understanding of climate change as a system comprising various components affecting the overall situation. They also revealed an understanding of the difference between weather and climate.     

An Answer to Schrödinger’s What Is Life?

That semiosis is specific to the living world is the cornerstone of biosemiotics. For checking an information-theoretic interpretation of this statement already proposed at the 2009 Biosemiotics Gathering in Prague, it is first attempted here to answer a question asked by Kupiec and Sonigo in Ni Dieu ni Gène (2000) on what differentiates living objects and those resulting from a geophysical process. Similar questions were asked by Schr?dinger in his essay What Is Life? where the emphasis was laid on the relationship of the atomic scale of the genes and the macroscopic scale of living beings. This essay was published in 1944, before information was introduced as a scientific entity, at a time when DNA was not yet identified as the vector of heredity. We undertake answering some of these questions, arguing that the living world is made of organisms, i.e., of assemblies possessing in a genome the information needed for their replication and their maintenance while the inanimate world only contains aggregates. In short, a biological process keeps its order through the use of information. For defining order, it is proposed that an orderly object can be produced by a construction (e.g., the copy of a template) using available data within some given context. In other words, replicating an orderly object does not bring new information into its context. Order in this meaning appears as specific to the living world, at variance with the inanimate world which is basically disorderly. A better understanding of what separates the living world from the inanimate world results: the use of information is the distinguishing feature which defines their border. Any living thing contains a symbolic information, referred to as its genome, inscribed into DNA molecules. This genome can indeed be copied but, its support being embedded in the physical world, it incurs disturbances which result in symbol errors. Keeping its order thus needs endowing any genome with error correction ability: it must belong to a redundant code, i.e., a set of sequences separated by some minimum distance. The larger its minimum distance, the more immune to errors are the elements of a code. Then genomes become as distinct as to ensure order. Identity and specificity result. Although conservative according to the above definition of order, the living world actually exhibits an extreme diversity which even tends to increase as evolution proceeds. In sharp contrast, homogeneity and monotony are observed in the inanimate world, assumed however non-conservative. In order to solve this paradox and justify the proposed definition of order, it is argued that the error-correcting means which ensure the conservation of genomes fail with some low, but non-zero, probability. Although very infrequent, regeneration errors result in genomes largely different from the initial ones; and the correction mechanisms conserve the mutated genomes just as the original ones. The operation of life changes scales, since the regeneration errors which originate in atomic events have observable consequences at the macroscopic scale.     

The early atmosphere: a new picture

Over the last several years, many of the fundamental ideas concerning the composition and chemical evolution of the Earth's early atmosphere have changed. While many aspects of this subject are clouded--either uncertain or unknown, a new picture is emerging. We are just beginning to understand how astronomical, geochemical, and atmospheric processes each contributed to the development of the gaseous envelope around the third planet from the sun some 4.6 billion years ago and how that envelope chemically evolved over the history of our planet. Simple compounds in that gaseous envelope, energized by atmospheric lightning and/or solar ultraviolet radiation, formed molecules of increasing complexity that eventually evolved into the first living systems on our planet. This process is called "chemical evolution" and immediately preceded biological evolution; once life developed and evolved, it began to alter the chemical composition of the atmosphere that provided the very essence of its creation. Photosynthetic organisms which have the ability to biochemically transform carbon dioxide and water to carbohydrates, which they use for food, produce large amounts of molecular oxygen (O2) as a by-product of the reaction. Atmospheric oxygen photochemically formed ozone, which absorbs ultraviolet radiation from the sun and shields the Earth's surface from this biologically lethal radiation. Once atmospheric ozone levels increased sufficiently, life could leave the safety of the oceans and go ashore for the first time. Throughout the history of our planet, there has been strong interaction between life and the atmosphere. Understanding our cosmic roots is particularly relevant as we embark on a search for life outside the Earth. At this very moment, several radio telescopes around the world are searching for extraterrestrial intelligence (SETI).     

A general definition of the heritable variation that determines the potential of a population to respond to selection

Genetic selection is a major force shaping life on earth. In classical genetic theory, response to selection is the product of the strength of selection and the additive genetic variance in a trait. The additive genetic variance reflects a population's intrinsic potential to respond to selection. The ordinary additive genetic variance, however, ignores the social organization of life. With social interactions among individuals, individual trait values may depend on genes in others, a phenomenon known as indirect genetic effects. Models accounting for indirect genetic effects, however, lack a general definition of heritable variation. Here I propose a general definition of the heritable variation that determines the potential of a population to respond to selection. This generalizes the concept of heritable variance to any inheritance model and level of organization. The result shows that heritable variance determining potential response to selection is the variance among individuals in the heritable quantity that determines the population mean trait value, rather than the usual additive genetic component of phenotypic variance. It follows, therefore, that heritable variance may exceed phenotypic variance among individuals, which is impossible in classical theory. This work also provides a measure of the utilization of heritable variation for response to selection and integrates two well-known models of maternal genetic effects. The result shows that relatedness between the focal individual and the individuals affecting its fitness is a key determinant of the utilization of heritable variance for response to selection.