scholarly journals Conjecture and hypothesis: The importance of reality checks

2017 ◽  
Vol 13 ◽  
pp. 620-624 ◽  
Author(s):  
David Deamer
Keyword(s):  
Origin Of Life ◽  
Fresh Water ◽  
Hydrothermal Vents ◽  
Origins Of Life ◽  
Weight Of Evidence ◽  
The Earth ◽  
Alternative Hypotheses ◽  
The Origin Of Life ◽  
The Difference ◽  
Hydrothermal Fields

In origins of life research, it is important to understand the difference between conjecture and hypothesis. This commentary explores the difference and recommends alternative hypotheses as a way to advance our understanding of how life can begin on the Earth and other habitable planets. As an example of how this approach can be used, two conditions have been proposed for sites conducive to the origin of life: hydrothermal vents in salty seawater, and fresh water hydrothermal fields associated with volcanic landmasses. These are considered as alternative hypotheses and the accumulating weight of evidence for each site is described and analyzed.

scholarly journals Serpentinite and the dawn of life

2011 ◽  
Vol 366 (1580) ◽  
pp. 2857-2869 ◽  
Author(s):  
Norman H. Sleep ◽  
Dennis K. Bird ◽  
Emily C. Pope
Keyword(s):  
Origin Of Life ◽  
Biological Material ◽  
Hydrothermal Vents ◽  
Chemical Potential ◽  
The Moon ◽  
Weakly Acid ◽  
The Earth ◽  
Potential Gradients ◽  
The Origin Of Life ◽  
Chemical Potential Gradients

Submarine hydrothermal vents above serpentinite produce chemical potential gradients of aqueous and ionic hydrogen, thus providing a very attractive venue for the origin of life. This environment was most favourable before Earth's massive CO 2 atmosphere was subducted into the mantle, which occurred tens to approximately 100 Myr after the moon-forming impact; thermophile to clement conditions persisted for several million years while atmospheric pCO 2 dropped from approximately 25 bar to below 1 bar. The ocean was weakly acid (pH ∼ 6), and a large pH gradient existed for nascent life with pH 9–11 fluids venting from serpentinite on the seafloor. Total CO 2 in water was significant so the vent environment was not carbon limited. Biologically important phosphate and Fe(II) were somewhat soluble during this period, which occurred well before the earliest record of preserved surface rocks approximately 3.8 billion years ago (Ga) when photosynthetic life teemed on the Earth and the oceanic pH was the modern value of approximately 8. Serpentinite existed by 3.9 Ga, but older rocks that might retain evidence of its presence have not been found. Earth's sequesters extensive evidence of Archaean and younger subducted biological material, but has yet to be exploited for the Hadean record.

Hydrothermal Conditions are Conducive for the Origin of Life

2019 ◽  
Author(s):  
David W. Deamer
Keyword(s):  
Physical Properties ◽  
Origin Of Life ◽  
Hydrothermal Vents ◽  
Field Work ◽  
Russian Language ◽  
Mineral Surfaces ◽  
Hydrothermal Conditions ◽  
Initial Field ◽  
The Origin Of Life ◽  
Hydrothermal Fields

Alexander Ivanovich Oparin was first to consider the origin of life in strictly scientific terms. Oparin published The Origin of Life in 1924, in his native Russian language, and was active in the field for the next 50 years. During my initial field work in the volcanic regions of Kamchatka, organized with Vladimir Kompanichenko, we visited the Institute of Volcanology and Seismology in Petropavlovsk, and I happened to see the above quote painted on a wall near the entrance. Oparin’s proposal about how life can begin was intuitive because he had no experimental evidence as a foundation, but as our party rode in helicopters up and down the peninsula from one volcanic site to the next, I began to share his intuition. The focus of this chapter concerns the properties of water in contact with mineral surfaces heated by volcanism, inspired by what we saw in Kamchatka. Four billion years ago, as the global temperature decreased following the condensation of the ocean, there came a point at which the components required for the origin of life could assemble into systems of encapsulated polymers. Two alternative hydrothermal conditions have been proposed as sites where this could have occurred: salty seawater at submarine hydrothermal vents and freshwater circulating in hydrothermal fields associated with volcanic land masses. To weigh the alternatives, this chapter considers the chemical and physical properties of hydrothermal vents and hydrothermal fields and how each could contribute to the origin of cellular life. Questions to be addressed: What are the chemical and physical properties of hydrothermal vents? How do the properties of hydrothermal fields differ from those of vents? How are these properties related to the way that organic solutes can undergo physical and chemical interactions related to the origin of life? Suppose that an organic chemist decides to synthesize a new compound that involves making an ester bond. The chemist is provided with a solution of the two reactants such as acetic acid and ethanol, and then is given a choice: should the reaction be run in an ice bath or instead heated to boiling and refluxed?

scholarly journals Montmorillonite-catalysed formation of RNA oligomers: the possible role of catalysis in the origins of life

2006 ◽  
Vol 361 (1474) ◽  
pp. 1777-1786 ◽  
Author(s):  
James P Ferris
Keyword(s):  
Origin Of Life ◽  
Volcanic Ash ◽  
Origins Of Life ◽  
Reaction Conditions ◽  
The Earth ◽  
Rna Oligomers ◽  
The Origin Of Life ◽  
Large Deposits

Large deposits of montmorillonite are present on the Earth today and it is believed to have been present at the time of the origin of life and has recently been detected on Mars. It is formed by aqueous weathering of volcanic ash. It catalyses the formation of oligomers of RNA that contain monomer units from 2 to 30–50. Oligomers of this length are formed because this catalyst controls the structure of the oligomers formed and does not generate all possible isomers. Evidence of sequence-, regio- and homochiral selectivity in these oligomers has been obtained. Postulates on the role of selective versus specific catalysts on the origins of life are discussed. An introduction to the origin of life is given with an emphasis on reaction conditions based on the recent data obtained from zircons 4.0–4.5 Ga.

Prospects for Life on Other Planets

2019 ◽  
Author(s):  
David W. Deamer
Keyword(s):  
Solar System ◽  
Origin Of Life ◽  
Hydrothermal Vents ◽  
European Space Agency ◽  
Extraterrestrial Life ◽  
Major Question ◽  
Space Agency ◽  
Planetary Bodies ◽  
The Origin Of Life ◽  
Alternative Scenarios

This book describes a hypothetical process in which populations of protocells can spontaneously assemble and begin to grow and proliferate by energy- dependent polymerization. This might seem to be just an academic question pursued by a few dozen researchers as a matter of curiosity, but in the past three decades advances in engineering have reached a point where both NASA and the European Space Agency (ESA) routinely send spacecraft to other planetary objects in our solar system. A major question being pursued is whether life has emerged elsewhere than on Earth. The limited funds available to support such missions require decisions to be made about target priorities that are guided by judgment calls. These in turn depend on plausible scenarios related to the origin of life on habitable planetary surfaces. We know that other planetary bodies in our solar system have had or do have conditions that would permit microbial life to exist and perhaps even to begin. By a remarkable coincidence, the two most promising objects for extraterrestrial life happen to represent the two alternative scenarios described in this book: An origin of life in conditions of hydrothermal vents or an origin in hydrothermal fields. This final chapter will explore how these alternative views can guide our judgment about where to send future space missions designed as life-detection missions. Questions to be addressed: What is meant by habitability? Which planetary bodies are plausible sites for the origin of life? How do the hypotheses described in this book relate to those sites? There is healthy public interest in how life begins and whether it exists elsewhere in our solar system or on the myriad exoplanets now known to orbit other stars. This has fueled a series of films, television programs, and science fiction novels. Most of these feature extrapolations to intelligent life but a few, such as The Andromeda Strain, explore what might happen if a pathogenic organism from space began to spread to the human population. There is a serious and sustained scientific effort—SETI, or Search for Extraterrestrial Intelligence—devoted to finding an answer to this question.

General discussion after session V

1988 ◽  
Vol 325 (1587) ◽  
pp. 611-618 ◽  
Keyword(s):  
Origin Of Life ◽  
Time Perspective ◽  
Applied Mathematics ◽  
Building Blocks ◽  
Living Systems ◽  
Organic Chemical ◽  
General Terms ◽  
The Earth ◽  
The Origin Of Life ◽  
Emergence Of Life

N. C. Wickramasinghe ( Department of Applied Mathematics and Astronomy, University College, Cardiff, U. K. ). The question of the origin of life is, of course, one of the most important scientific questions and it is also one of the most difficult. One is inevitably faced here with a situation where there are very few empirical facts of direct relevance and perhaps no facts relating to the actual transition from organic material to material that can even remotely be described as living. The time perspective of events that relate to this problem has already been presented by Dr Chang. Uncertainty still persists as to the actual first moment of the origin or the emergence of life on the Earth. At some time between 3800 and 3300 Ma BP the first microscopic living systems seem to have emerged. There is a definite moment in time corresponding to a sudden appearance of cellular-type living systems. Now, traditionally the evolution of carbonaceous compounds which led to the emergence of life on Earth could be divided into three principal steps and I shall just remind you what those steps are. The first step is the production of chemical building blocks that lead to the origin of the organic molecules necessary as a prerequisite for the evolution of life. Step two can be described in general terms as prebiotic evolution, the arrangement of these chemical units into some kind of sequence of precursor systems that come almost up to life but not quite; and then stage three is the early biological evolution which actually effects the transition from proto-cellular organic-type forms into truly cellular living systems. The transition is from organic chemistry, prebiotic chemistry to biochemistry. Those are the three principal stages that have been defined by traditional workers in the field, the people who, as Dr Chang said, have had the courage to make these queries and attempt to answer them. Ever since the classic experiments where organic materials were synthesized in the laboratory a few decades back, it was thought that the first step, the production of organic chemical units, is important for the origin of life on the Earth, and that this had to take place in some location on the Earth itself.

How Did It All Begin?: The Self-Assembly of Organic Molecules and the Origin of Cellular Life

2002 ◽  
Vol 11 ◽  
pp. 179-194
Author(s):  
David W. Deamer
Keyword(s):  
Origin Of Life ◽  
20Th Century ◽  
Self Assembly ◽  
Organic Molecules ◽  
Western Culture ◽  
The Self ◽  
Late 20Th Century ◽  
Cellular Life ◽  
The Earth ◽  
The Origin Of Life

Movies are the myths of late-20th century western culture. Because of the power of films likeETto capture our imagination, we are more likely than past generations to accept the possibility that life exists elsewhere in our galaxy. Such a myth can be used to sketch the main themes of this chapter, which concern the origin of life on the Earth.

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 Scum of the Earth: A Hypothesis for Prebiotic Multi-Compartmentalised Environments

Life ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 976
Author(s):  
Craig Robert Walton ◽  
Oliver Shorttle
Keyword(s):  
Origin Of Life ◽  
Prebiotic Chemistry ◽  
Near Surface ◽  
Microbial Biofilms ◽  
The Earth ◽  
Rock Record ◽  
Universal Feature ◽  
The Origin Of Life ◽  
New Hypothesis ◽  
Surface Environment

Compartmentalisation by bioenergetic membranes is a universal feature of life. The eventual compartmentalisation of prebiotic systems is therefore often argued to comprise a key step during the origin of life. Compartments may have been active participants in prebiotic chemistry, concentrating and spatially organising key reactants. However, most prebiotically plausible compartments are leaky or unstable, limiting their utility. Here, we develop a new hypothesis for an origin of life environment that capitalises upon, and mitigates the limitations of, prebiotic compartments: multi-compartmentalised layers in the near surface environment—a ’scum’. Scum-type environments benefit from many of the same ensemble-based advantages as microbial biofilms. In particular, scum layers mediate diffusion with the wider environments, favouring preservation and sharing of early informational molecules, along with the selective concentration of compatible prebiotic compounds. Biofilms are among the earliest traces imprinted by life in the rock record: we contend that prebiotic equivalents of these environments deserve future experimental investigation.

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