The origin of life and the definition of life

2011 ◽  
pp. 174-186
Author(s):  
Storrs McCall
Keyword(s):  
Origin Of Life ◽  
Definition Of Life ◽  
The Origin Of Life ◽  
Definition Of

What is life?

1997 ◽  
Author(s):  
John Maynard Smith ◽  
Eors Szathmary
Keyword(s):  
Natural Selection ◽  
Origin Of Life ◽  
Definition Of Life ◽  
The Sun ◽  
Physical Processes ◽  
Living Things ◽  
Survival And Reproduction ◽  
The Origin Of Life ◽  
Definition Of ◽  
Life On Earth

Imagine that, when the first spacemen step out of their craft onto the surface of one of the moons of Jupiter, they are confronted by an object the size of a horse, rolling towards them on wheels, and bearing on its back a concave disc pointing towards the Sun. They will at once conclude that the object is alive, or has been made by something alive. If all they find is a purple smear on the surface of the rocks, they will have to work harder to decide. This is the phenotypic approach to the definition of life: a thing is alive if it has parts, or ‘organs’, which perform functions. William Paley explained the machine-like nature of life by the existence of a creator: today, we would invoke natural selection. There are, however, dangers in assuming that any entity with the properties of a self-regulating machine is alive, or an artefact. In section 2.2, we tell the story of a self-regulating atomic reactor, the Oklo reactor, which is neither. This story can be taken in one of three ways. First, it shows the dangers of the phenotypic definition of life: not all complex entities are alive. Second, it illustrates how the accidents of history can give rise spontaneously to surprisingly complex machine-like entities. The relevance of this to the origin of life is obvious. In essence, the problem is the following. How could chemical and physical processes give rise, without natural selection, to entities capable of hereditary replication, which would therefore, from then on, evolve by natural selection? The Oklo reactor is an example of what can happen. Finally, section 2.2 can simply be skipped: the events were interesting, but do not resemble in detail those that led to the origin of life on Earth. There is an alternative to the phenotypic definition of life. It is to define as alive any entities that have the properties of multiplication, variation and heredity. The logic behind this definition, first proposed by Muller (1966), is that a population of entities with these properties will evolve by natural selection, and hence can be expected to acquire the complex adaptations for survival and reproduction that are characteristic of living things.

scholarly journals The Generalized Definition of Life

2021 ◽  
Author(s):  
vivek kumar
Keyword(s):  
Origin Of Life ◽  
Life Forms ◽  
Living Systems ◽  
Definition Of Life ◽  
The Origin Of Life ◽  
Definition Of ◽  
Life On Earth

In this article, I propose and discuss a new definition of life. This new definition considers reproduction and evolution as major aspects of life. It brings into consideration a variety of other life forms like inorganic life, etc. In this study, I aim to present the possibility of various life forms and some of their properties, which might help understand the origin of life on earth and the existence of life in other parts of the cosmos. This new proposed definition of life is independent of the mode of evolution and general enough to consider all potential life forms. This article uses NASA’s definition of life as a structure to derive this generalized definition of life. Finding and exploring new living systems will definitely be very helpful in understanding the aspects of life. In order to explain some complex life forms, a new concept of addition of living systems is introduced in this article. This study underscores the need for further work to understand the origin and properties of living systems.

scholarly journals In Medias Res: A Resolution of Some False Dichotomies in Origins of Life Research

2018 ◽  
Author(s):  
Donald Frohlich ◽  
Richard Austin Choate
Keyword(s):  
Origin Of Life ◽  
Body Problem ◽  
Scientific Research ◽  
Origins Of Life ◽  
Definition Of Life ◽  
First Case ◽  
The Origin Of Life ◽  
Mind Body Problem ◽  
Definition Of ◽  
The Mind

In this paper, we address some of the false dichotomies that pervade contemporary scientific and philosophical research about the origin of life. These dichotomies can be divided into two categories, the methodological and the conceptual. In the first case, we focus on providing an alternative to the problems and paradoxes which arise from trying to eliminate a definition of life from scientific research into life’s origins. In the second case, we illustrate how origin of life research is confined by the same conceptual paradigm which continues to plague the mind-body problem. Based on this analysis, we then offer some general criteria that a definition of life should meet.

Understanding Life: A Bioinformatics Perspective

2016 ◽  
Vol 25 (2) ◽  
pp. 231-245 ◽  
Author(s):  
Natalia Szostak ◽  
Szymon Wasik ◽  
Jacek Blazewicz
Keyword(s):  
Origin Of Life ◽  
Rna World ◽  
Origins Of Life ◽  
Life Itself ◽  
Wet Lab ◽  
The Origin Of Life ◽  
To Come ◽  
World Hypothesis ◽  
Definition Of ◽  
Rna World Hypothesis

According to some hypotheses, from a statistical perspective the origin of life seems to be a highly improbable event. Although there is no rigid definition of life itself, life as it is, is a fact. One of the most recognized hypotheses for the origins of life is the RNA world hypothesis. Laboratory experiments have been conducted to prove some assumptions of the RNA world hypothesis. However, despite some success in the ‘wet-lab’, we are still far from a complete explanation. Bioinformatics, supported by biomathematics, appears to provide the perfect tools to model and test various scenarios of the origins of life where wet-lab experiments cannot reflect the true complexity of the problem. Bioinformatics simulations of early pre-living systems may give us clues to the mechanisms of evolution. Whether or not this approach succeeds is still an open question. However, it seems likely that linking efforts and knowledge from the various fields of science into a holistic bioinformatics perspective offers the opportunity to come one step closer to a solution to the question of the origin of life, which is one of the greatest mysteries of humankind. This paper illustrates some recent advancements in this area and points out possible directions for further research.

scholarly journals Beauty of Life in Dynamical Systems: An Aesthetic Viewpoint of Life

2018 ◽  
Author(s):  
soumya banerjee
Keyword(s):  
Deep Learning ◽  
Dynamical Systems ◽  
Origin Of Life ◽  
Life Forms ◽  
Definition Of Life ◽  
Computational Framework ◽  
Aesthetic Sense ◽  
Forms Of Life ◽  
Definition Of ◽  
Answering Questions

This submission emphasizes the beauty of mathematics and dynamical systems especially in questions around origin of life. Our conception of life is shaped by what we see around us on Earth. What life forms might we expect to see on alien planets? Would they be carbon-based like us or can they be even more exotic? Answering questions like these mean we must come up with an objective definition of life. We have previously hypothesized that an objective definition of life is that it should be capable of information processing.Our work also suggests that we may need an “aesthetic sense” to recognize life we have never seen before. Such aesthetic versions of life-like systems can be generated using the computational framework presented here. Our computational framework combines dynamical systems with deep learning to generate aesthetically appealing forms of life-like systems.

Can stabilization and symmetry breakings give rise to life in the process of the universe evolution?

2018 ◽  
Vol 18 (4) ◽  
pp. 311-315
Author(s):  
Choong Sun Kim
Keyword(s):  
Origin Of Life ◽  
Molecular System ◽  
Planck Scale ◽  
Atomic Scale ◽  
Left Handed ◽  
Scale Down ◽  
The Origin Of Life ◽  
Definition Of ◽  
The Universe ◽  
Universe Evolution

AbstractBiogenesis can be understood as the final process of the Universe's evolution, from Planck scale down to nuclear scale to atomic scale to molecular scale, then finally to bioscale, with the breaking of relevant symmetries at every step. By assuming the simplest definition of life, that life is just a molecular system which can reproduce itself (auto-reproducing molecular system – ARMS) and has such kinetic ability (kineto-molecular system), at least for its microscopic level, as to respond actively to its surrounding environments, we tried to explain the origin of life, taking the final step of the Universe evolution. We found a few clues for the origin of life, such as: (1) As the Universe expands and gets extremely cold, biogenesis can take place by ARMS, new level of stabilization may be achievable only at ‘locally cold places’ (LCPs), such as comets. (2) There must be the parity breaking in the bioscale stabilization process, which can be violated spontaneously, or dynamically by the van der Waals forces possible only at LCPs. (3) The rule of bioparity breaking is universal within the biohorizon. So we will find, e.g. only left-handed amino acids in all living beings dwelling within our Galaxy. (4) The idea of biogenesis through the bioscale stabilization in the evolution of the Universe looks very consistent with Panspermia hypothesis and supports it by providing a viable answer for life's origin at such LCPs.

The Tempo and mode(S) of Prebiotic Evolution

1997 ◽  
Vol 161 ◽  
pp. 419-429 ◽  
Author(s):  
Antonio Lazcano
Keyword(s):  
Origin Of Life ◽  
Organic Compounds ◽  
Biological Evolution ◽  
Current Evidence ◽  
Early Diversification ◽  
Time Period ◽  
The Galaxy ◽  
History Of ◽  
Widespread Phenomenon ◽  
The Origin Of Life

AbstractDifferent current ideas on the origin of life are critically examined. Comparison of the now fashionable FeS/H2S pyrite-based autotrophic theory of the origin of life with the heterotrophic viewpoint suggest that the later is still the most fertile explanation for the emergence of life. However, the theory of chemical evolution and heterotrophic origins of life requires major updating, which should include the abandonment of the idea that the appearance of life was a slow process involving billions of years. Stability of organic compounds and the genetics of bacteria suggest that the origin and early diversification of life took place in a time period of the order of 10 million years. Current evidence suggest that the abiotic synthesis of organic compounds may be a widespread phenomenon in the Galaxy and may have a deterministic nature. However, the history of the biosphere does not exhibits any obvious trend towards greater complexity or «higher» forms of life. Therefore, the role of contingency in biological evolution should not be understimated in the discussions of the possibilities of life in the Universe.

Photochemical Evolution of Interstellar/Precometary Organic Material

1997 ◽  
Vol 161 ◽  
pp. 23-47 ◽  
Author(s):  
Louis J. Allamandola ◽  
Max P. Bernstein ◽  
Scott A. Sandford
Keyword(s):  
Origin Of Life ◽  
Building Blocks ◽  
Complex Species ◽  
Infrared Observations ◽  
Interstellar Ice ◽  
Polycyclic Aromatic ◽  
Ultraviolet Photolysis ◽  
The Origin Of Life ◽  
Simple Molecules ◽  
Complex Organic

AbstractInfrared observations, combined with realistic laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the building blocks of comets. Since comets are thought to be a major source of the volatiles on the primative earth, their organic inventory is of central importance to questions concerning the origin of life. Ices in molecular clouds contain the very simple molecules H2O, CH3OH, CO, CO2, CH4, H2, and probably some NH3and H2CO, as well as more complex species including nitriles, ketones, and esters. The evidence for these, as well as carbonrich materials such as polycyclic aromatic hydrocarbons (PAHs), microdiamonds, and amorphous carbon is briefly reviewed. This is followed by a detailed summary of interstellar/precometary ice photochemical evolution based on laboratory studies of realistic polar ice analogs. Ultraviolet photolysis of these ices produces H2, H2CO, CO2, CO, CH4, HCO, and the moderately complex organic molecules: CH3CH2OH (ethanol), HC(= O)NH2(formamide), CH3C(= O)NH2(acetamide), R-CN (nitriles), and hexamethylenetetramine (HMT, C6H12N4), as well as more complex species including polyoxymethylene and related species (POMs), amides, and ketones. The ready formation of these organic species from simple starting mixtures, the ice chemistry that ensues when these ices are mildly warmed, plus the observation that the more complex refractory photoproducts show lipid-like behavior and readily self organize into droplets upon exposure to liquid water suggest that comets may have played an important role in the origin of life.

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