The Origin of Life

2014 ◽  
Author(s):  
S. Blair Hedges
Keyword(s):  
Origin Of Life ◽  
Hydrothermal Vents ◽  
Biological Evolution ◽  
Early Time ◽  
Molecular Clocks ◽  
Time Period ◽  
A Cell ◽  
The Origin Of Life ◽  
Successive Generations ◽  
Life On Earth

Biological evolution begins with the origin of life, but the subject is the perhaps the most interdisciplinary of any in science. Understanding how life began on Earth requires knowledge of the astronomical, geological, and atmospheric settings. However, those settings are in turn dependent on knowing the time period when life arose, which comes from the fossil and molecular records, including molecular clocks based on genetic mutations. Interrelated with the setting is the chemistry that generates the organic molecules used to assemble the first cells and carry the genetic information to successive generations of cells. But holding the chemical reactions and products together in a cell requires a membrane, and the assembly of that involves biophysics. Thus, we have all of the fields of science coming together to understand a single event that happened about four billion years ago and initiated the Tree of Life on Earth. Because little evidence of anything has remained from this early time, there have been enormous amounts of published speculation on this subject. Narratives on how life originated can be grouped by location (surface versus submarine hydrothermal vents), temperature (cold versus hot), source of energy (heterotrophic versus autotrophic), and evolutionary order (genetics-first versus metabolism-first). I use the last dichotomy here, only because it has a long history and renewed focus in recent years. Currently there is no consensus on any one theory for the origin of life, but this is an active field that has made great strides in recent decades.

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.

A symbiotic view of the origin of life at hydrothermal impact crater-lakes

2016 ◽  
Vol 18 (30) ◽  
pp. 20033-20046 ◽  
Author(s):  
Sankar Chatterjee
Keyword(s):  
Origin Of Life ◽  
Early Life ◽  
Hydrothermal Vents ◽  
Impact Crater ◽  
Crater Lakes ◽  
Origin And Evolution ◽  
The Origin Of Life ◽  
Life On Earth

Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth.

scholarly journals Origins of Life

2020 ◽  
pp. 2-7
Author(s):  
Hannah Mahoney
Keyword(s):  
Origin Of Life ◽  
Hydrothermal Vents ◽  
Rna World ◽  
Relevant Information ◽  
Future Research ◽  
Specific Chemical ◽  
Scientific Disciplines ◽  
Earth Environment ◽  
The Origin Of Life ◽  
Life On Earth

When, where, and how did life on Earth originate? The origin of life problem involves multiple scientific disciplines and has spanned multiple decades. It can be summarized into three stages: (1) the origin of biological monomers, (2) the origin of biological polymers, and (3) the emergence and evolution of cells. While highly speculative, the connections between these stages are theorized by attempting to determine the geochemical situations which could have driven chemical evolution and allow for the emergence of specific chemical functions of biological systems. This review summarizes reported findings relevant to the early Earth environment and the main theories in the origin of life subject. Specific focus is placed on the metabolism first, RNA world, and compartmentalization first theories as they are involved in the origin of life paradox. The review then discusses submarine hydrothermal vents as a possible location for which life could have occurred. Understanding of information pertaining to the origin of life is important as it allows for advancement and discoveries in other fields of science and medicine. Overall, the aim of this review is to display the relevant information about the origin of life theory and highlight the importance of future research.

scholarly journals ‘Whole Organism’, Systems Biology, and Top-Down Criteria for Evaluating Scenarios for the Origin of Life

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 690
Author(s):  
Clifford F. Brunk ◽  
Charles R. Marshall
Keyword(s):  
Origin Of Life ◽  
Top Down ◽  
Chemical Systems ◽  
Biochemical Pathways ◽  
The Origin Of Life ◽  
Energy And Material Flows ◽  
Complex Scenario ◽  
Life On Earth ◽  
Physical Laws ◽  
Equilibrium Chemical

While most advances in the study of the origin of life on Earth (OoLoE) are piecemeal, tested against the laws of chemistry and physics, ultimately the goal is to develop an overall scenario for life’s origin(s). However, the dimensionality of non-equilibrium chemical systems, from the range of possible boundary conditions and chemical interactions, renders the application of chemical and physical laws difficult. Here we outline a set of simple criteria for evaluating OoLoE scenarios. These include the need for containment, steady energy and material flows, and structured spatial heterogeneity from the outset. The Principle of Continuity, the fact that all life today was derived from first life, suggests favoring scenarios with fewer non-analog (not seen in life today) to analog (seen in life today) transitions in the inferred first biochemical pathways. Top-down data also indicate that a complex metabolism predated ribozymes and enzymes, and that full cellular autonomy and motility occurred post-LUCA. Using these criteria, we find the alkaline hydrothermal vent microchamber complex scenario with a late evolving exploitation of the natural occurring pH (or Na+ gradient) by ATP synthase the most compelling. However, there are as yet so many unknowns, we also advocate for the continued development of as many plausible scenarios as possible.

Comparison of fundamental physical properties of the model cells (protocells) and the living cells reveals the need in protophysiology

2016 ◽  
Vol 16 (1) ◽  
pp. 97-104 ◽  
Author(s):  
V.V. Matveev
Keyword(s):  
Physical Properties ◽  
Origin Of Life ◽  
Sodium Pump ◽  
Molecular Model ◽  
Biological Evolution ◽  
Living Cells ◽  
Real Problem ◽  
The Origin Of Life ◽  
Physical Laws ◽  
Fundamental Physical

AbstractA hypothesis is proposed about potassium ponds being the cradles of life enriches the gamut of ideas about the possible conditions of pre-biological evolution on the primeval Earth, but does not bring us closer to solving the real problem of the origin of life. The gist of the matter lies in the mechanism of making a delimitation between two environments – the intracellular environment and the habitat of protocells. Since the sodium–potassium pump (Na+/K+-ATPase) was discovered, no molecular model has been proposed for a predecessor of the modern sodium pump. This has brought into life the idea of the potassium pond, wherein protocells would not need a sodium pump. However, current notions of the operation of living cells come into conflict with even physical laws when trying to use them to explain the origin and functioning of protocells. Thus, habitual explanations of the physical properties of living cells have become inapplicable to explain the corresponding properties of Sidney Fox's microspheres. Likewise, existing approaches to solving the problem of the origin of life do not see the need for the comparative study of living cells and cell models, assemblies of biological and artificial small molecules and macromolecules under physical conditions conducive to the origin of life. The time has come to conduct comprehensive research into the fundamental physical properties of protocells and create a new discipline – protocell physiology or protophysiology – which should bring us much closer to solving the problem of the origin of life.

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.

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