Origin of Life Theories

11 Key excerpts on "Origin of Life Theories"

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  What is Life? On Earth and Beyond

  On Earth and Beyond

  • Andreas Losch(Author)
  • 2017(Publication Date)
  • Cambridge University Press

    (Publisher)

  Then we will summarize our current understanding of the condi- tions that led from simple, abiotically synthesized monomers to some of the earliest chemical steps from which the basic metabolic steps first originated, and ultimately to macromolecules. A model is presented for the development of replicative sys- tems from random polymers that evolved through mutation and selection. Hence one can say that the origins of life mark the start of biological evolution. We present here a scheme based on simulation experiments and explanations in progress from which one can develop essential concepts of prebiotic synthesis, self- assembly of organic molecules, primeval catalysis and template-directed synthesis that can lead to general epistemological principles in the study of the origins of life. 1.1 The Concept of Origin Over the centuries, various ways of thinking have attempted to answer the question of origins, be they origins of the universe, of the living world or of human beings. The term origin has at least two meanings: (i) that which is located at the origin, at the beginning, (ii) that which is the basis, the foundation on which something is based. The universe and the solar system were formed billions of years ago in the great- est chaos. This is how Hesiode describes the origin of the world (Hesiode, 2001, 1 Reflections on Origins, Life, and the Origins of Life 15 Théogonie, 114–22): “at first arises Beance [the void], and then the Earth (Gaia) with broad sides, forever a robust foundation for all of us”. In the 1970s, Jim Lovelock and Lynn Margulis summarized the Greek myth in an ecological sense, to try to redraw the “basis” and the living tissue written within it. In this “Gaia hypothesis” life is tightly connected to the geochemical environment; it is the main message that has become famous in the climatic evolution of today, on which the survival of numerous species depends. Accordingly, biodiversity draws its origins from the origins of life itself.

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  The Cambridge Encyclopedia of Darwin and Evolutionary Thought

  • Michael Ruse(Author)
  • 2013(Publication Date)
  • Cambridge University Press

    (Publisher)

  Yet, because so far no complete scientific scenario of the ori- gin of life was experimentally demonstrated, the origin-of-life question is often regarded even by adherents to science as the “soft underbelly of evolutionary biology” (Scott 1996). Considering the lack of full empirical validation of origin-of- life theories, some scientists and philosophers of biology prefer at the moment not to make the natural emergence of life “an issue” in debating religious believers (Ruse 2001; De Duve 2002). Indeed, the presence or absence of empirical validation is a crucial issue. It is the aim of scientists to corroborate hypoth- eses and, where possible, to gather supporting empirical evi- dence. Unlike religious claims about the role of a supernatural agent in nature, which in principle are not open to empirical assessment, scientific hypotheses are testable and, at least in the long run, can be refuted or confirmed. But this empiri- cal distinction of science does not fully describe its unique nature. Science today is characterized by the interaction between specific empirical claims and a broader philosophi- cal naturalistic worldview that eschews purposeful explana- tions. This interaction, originating and developing first in the physical sciences in the seventeenth century, is now also the hallmark of biology. The notion that the phenomena of life can be explained naturally on the basis of evolution became a possibility after Darwin’s Origin in 1859. It was subsequently established in the first half of the twentieth century as the framework that gives a unified sense to everything in biology (Dobzhansky 1973). Philosophical conceptions, unlike empirical claims, can- not be refuted or confirmed. However, based to a large extent on the empirical achievements of the natural sciences dur- ing the past few hundred years, the evolutionary naturalis- tic worldview is by now strongly substantiated (Fry 2009, 2012).

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  The Biosphere

  • Natarajan Ishwaran(Author)
  • 2012(Publication Date)
  • IntechOpen

    (Publisher)

  These conceptions ignore the problem of longtime existence and evolution of the earliest forms of life on the Earth. Moreover, they overlook the problem of the origin of the biosphere – unique milieu for early organisms survivorship and reproduction. Therefore we suppose that origin of earthly life and the origin of the biosphere are aspects of a whole indivisible process (Levchenko, 2010, 2011). Hence, we consider the appearance of such conditions on the early planet, which guaranteed the origin and survivorship of organic life. We suppose also that primary organisms should be incorporated in natural geological processes, accelerating them and transforming surroundings in directions favorable for the creation of higher forms of life. The abiogenesis (or biopoiesis) hypothesis claims that life emerged from non-living matter in early terrestrial conditions. This is the traditional approach to the question of life’s origin. Main questions of abiogenesis hypothesis are reduced to an origin of biological membranes via emergence of ionic asymmetry of the cells and chiral asymmetry of biomolecules, and to the problem of the appearance of matrix synthesis and polymer molecules which are able to store hereditary information. Below we will give a brief review of the different hypotheses. In order to find out the regularities of the pre-biosphere development, features of processes of evolution and development for different biological systems were considered and the embryosphere hypothesis (Levchenko, 1993, 2002, 2011) proposed. According to it, the The Biosphere 4 appearance of different sub-systems of primary organisms could happen independently from each other within an united functional system called an embryosphere. This is a system with a self-regulated process of that allows the interchange of substances between its different parts under the influence of external energy flows.

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  Mapping the Origins Debate

  Six Models of the Beginning of Everything

  • Gerald Rau(Author)
  • 2012(Publication Date)
  • IVP Academic

    (Publisher)

  4   Origin of Life

     

  A biogenesis , the scientific name for the origin of life, is a topic many biologists seem to want to dodge, in spite of the fact that their profession would not exist had it not occurred, to say nothing of the professors. It is glossed over in the evolution unit of biology textbooks with a quick obligatory reference to the Miller-Urey experiment. When students ask about it, teachers often repeat the line found in many textbooks and other places that evolution is the study of how life changed, not how it started in the first place. While this may be true, it is also more than a little disingenuous, since it is a valid scientific question, one that obviously is closely related to evolution as shown by the fact that evolutionary scientists now routinely talk about *prebiotic evolution.

  So why is there so much reluctance to talk about the topic? Mostly because there is so little evidence and no good proposed mechanism for how life could have arisen. That may sound like an extreme statement, but it is true.[1] There are several proposals on the table describing how different parts of the process might have occurred, but nothing even vaguely resembling an overall explanation. Ultimately, whether we accept a natural or supernatural explanation is largely based on our philosophical presuppositions, because real evidence is nearly nonexistent.

  4.1 What Is the Evidence?

  One of the biggest problems in discussing the origin of life is there is no record of what happened, and in all likelihood, no direct evidence will ever be found. Molecules do not fossilize, although sometimes we may be able to infer the existence of certain elements or compounds from the presence of certain minerals. Single cells fossilize rarely, and even when they do, they leave few clues that would help us to determine the details of their structure.

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  The Evolution Delusion

  How to Recognize the Unsupported Claims of Darwin's Theory

  • Bart Rask, MD(Authors)
  • 2021(Publication Date)
  • Universal Publishers

    (Publisher)

  Chapter 8

  The Origin of Life

  S ome evolutionists believe that the elements of life, such as its biochemicals and cells, were simply the result of a random conglomeration of molecules, and that “[t]he origin of life is also the origin of evolution” (Nowak and Ohtsuki 2008:14,924). This hypothetical process, known as abiogenesis , is supposed to explain how biological life could have emerged from a lifeless universe. Other evolutionists have reservations about extending the theory of evolution from the origin of species to the origin of life. Richard Dawkins (2009) admits that the spontaneous origin of life from the inanimate is difficult to conceive:

  Evidently, the spontaneous generation of life is a very rare event, but it must have happened once, and this is true whether you think the original spontaneous generation was a natural or supernatural event… We have no evidence about what the first step in making life was, but we do know the kind of step it must have been. It must have been whatever it took to get natural selection started. Before that first step, the sorts of improvement that only natural selection can achieve were impossible. And that means the key step was the arising, by some process yet unknown, of a self-replicating entity. (pp. 418–419)

  Theobald (2012) classifies the origin of life from the inanimate as a separate phenomenon from evolution:

  [A]biogenesis is an independent hypothesis. In evolutionary theory it is taken as axiomatic that an original self-replicating life-form existed in the distant past, regardless of its origin.

  Evolution critics argue that the self-assembly of simple molecules into complex biochemicals is contrary to the second law of thermodynamics which states that the entropy (i.e., disorder) of a closed system (i.e., the Earth) will always increase. Evolutionists counter by claiming that the system (Earth) is not closed, because the energy supplied by the sun could potentially increase molecular complexity (decrease entropy) on Earth while increasing the entropy in the sun. This chapter reviews the explanations in the scientific literature about how the molecules of life—and life per se—may have originated.

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  Planetary Geoscience

  • Harry Y. McSween, Jr, Jeffrey E. Moersch, Devon M. Burr, William M. Dunne, Joshua P. Emery, Linda C. Kah, Molly C. McCanta(Authors)
  • 2019(Publication Date)
  • Cambridge University Press

    (Publisher)

  16 Astrobiology: A Planetary Perspective on Life At its root, the word “astrobiology” means “biology of the stars.” It is the branch of science that concerns the origin and evolution of life on Earth – the only place that, at present, we are certain life exists – and the potential for life to be distributed across the Universe. In this chapter, we explore the evolutionary relationships of life on Earth and review the necessary ingredients and permissible environmental conditions for the origin and evolution of life. We also discuss the characteristics of early life on Earth, and the physical and geochemical evidence for life that might be used to target habitable environments – and potentially to detect evidence of life – elsewhere in the Universe. 16.1 The Diversity of Life In 2003, the Hubble Space Telescope focused its lens at a single, dark and seemingly featureless spot in the Uni- verse. At the end of 11 days, Hubble had gathered enough visible, near-infrared, and UV light to identify thousands of new galaxies, each containing billions of individual stars (Figure 16.1). This astounding image brings to mind an idea first articulated by Metrodorus in 400 BC, that “it is unnatural in a large field to have only one stalk of wheat, and in the infinite universe, only one living world.” This astounding image brought new life to field of astrobiology. Among the many challenges of astrobiology is finding a solution to the seemingly simple question of what is life? Typically, we consider life as a series of observable characteristics: life has an ordered structure (cells), built around a chemical blueprint (genetic material), that responds to its environment; life utilizes energy (metab- olism) and shows growth; life is capable of reproduction. Although these characteristics are helpful in considering what to look for when investigating the potential for life in terrestrial and extraterrestrial environments, none of these characteristics are unique to life.

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  Fundamentals of Geobiology

  • Andrew H. Knoll, Don E. Canfield, Kurt O. Konhauser, Andrew H. Knoll, Don E. Canfield, Kurt O. Konhauser(Authors)
  • 2012(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  17 GEOCHEMICAL ORIGINS OF LIFE

  Robert M. Hazen

  Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC 20015, USA

  17.1 Introduction

  Life’s origins were a sequence of geochemical events, the consequence of interactions among atmosphere, oceans, and rocks in an energetic prebiotic environment. While the details of that ancient transformation from geochemistry to biochemistry remain elusive, the general outlines of life’s origins are gradually emerging through a combination of laboratory experiments, observations of living cells, and theoretical analysis.

  The experimental investigation of the origins of life commenced in earnest more than a half-century ago with the pioneering work of Miller (Miller, 1953, 1955; Wills and Bada, 2000; Lazcano, 2010), who synthesized many of life’s molecular building blocks under what were then thought to be plausible prebiotic conditions. Despite an initial euphoric sense that the origin mystery would be solved quickly, scientists soon realized that the natural transition from rock, water and gas to living cells, though completely consistent with the laws of chemistry and physics, would not quickly be deduced by the scientific method.

  The central challenge of origins research lies in replicating in a laboratory setting the extraordinary increase in complexity that is required to evolve from isolated small molecules to a living cell. This chapter reviews some of the efforts by origins-of-life researchers to induce such increases in complexity. A unifying theme of these studies, and hence a useful organizing framework for this review, is the principle of emergence – the natural process by which complexity arises. We will find repeatedly that geochemical complexities – notably thermal and compositional gradients, fluid fluxes, cycles, and interfaces – are essential attributes of early Earth’s geochemical environment that promote the emergence of chemical complexification (Hazen, 2009; Hazen and Sverjensky, 2010).

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  Investigating Seafloors and Oceans

  From Mud Volcanoes to Giant Squid

  • Antony Joseph(Author)
  • 2016(Publication Date)
  • Elsevier

    (Publisher)

  As noted earlier, some Darwinists suggest that the common ancestor somehow evolved from nonliving matter (which they presume to be some kind of dirty-water soup-like composition as found in submarine hydrothermal vents and volcanoes). In this sense, submarine hydrothermal vents have become important to the “origin of life” studies.

  However, there are researchers who believe that certain chemical constraints make abiogenesis (ie, life arising from nonlife) an impossible event. Perhaps the most radical claim of the theory of evolution through natural selection is that “elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner” evolved from the simplest forms of life by a few simple principles.

  5.4 Chemical Evolution of Life-Supporting Structures

  There is evidence to believe that life originated on Earth about 4.1–3.8 billion years ago; that is, life did not exist on this planet before this “biotic era.” Unlike in religious beliefs, in which no evidence is sought by the believer for what he/she believes in, nothing that unambiguously passes the test of experimental evidence is treated as truth in science. Thus, mere assumption or hypothesis of a “spontaneous origin of life from nonliving matter” at the end of the “prebiotic era” needed to be tested before accepting it as a scientific truth. Essential to the spontaneous origin of life was the availability of organic molecules as building blocks.

  5.4.1 Amino Acids

  The importance of amino acids in the context of origin of life stems from the fact that amino acids are essential to life. Amino acids are biologically important organic compounds composed of amine ( NH2 ) and carboxylic acid ( COOH) functional groups, along with a side chain specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, though other elements are found in the side chains of certain amino acids. About 500 amino acids are known (Wagner and Musso, 1983 ), and can be classified in many ways. Amino acids are natural molecules that form a very large network of molecules, known as proteins, by a process of polymerization; that is, by chemical binding to other molecules. Thus, proteins are simply amino acid polymers. In other words, amino acids are the building blocks of proteins; that is, the structural units (monomers) that make up proteins. They join together to form short polymer chains called peptides or longer chains called either polypeptides or proteins. These polymers are linear and unbranched, with each amino acid within the chain attached to two neighboring amino acids. The process of making proteins is called translation and involves the step-by-step addition of amino acids to a growing protein chain by a ribozyme (Wagner and Musso, 1983

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  Frontiers of Astrobiology

  • Chris Impey, Jonathan Lunine, José Funes(Authors)
  • 2012(Publication Date)
  • Cambridge University Press

    (Publisher)

  Until this paradox is resolved by some appropriate combination of chemistry and environment, the “origins” problem will not be solved. Synthesizing life from scratch Of course, even if a laboratory experiment does generate RNA from plau- sible prebiotic precursors, the result need not offer us a constraint-by-origin view of what forms life might take universally. After all, molecules other than RNA might be able to simultaneously support genetics and catalysis. These too might be able to straddle non-Darwinian and Darwinian chemistry in a way that leads to their own form of life, possibly quite different from the life we know on Earth, and possibly in environments quite different from those found on early Earth. This observation suggests a fourth approach to understanding life as a universal. This approach, represented by the right wedge in Figure 2.1, comes under the title “synthetic biology.” Synthesis, especially in chemistry, reflects first a definition of understanding as an ability to create. If we truly understand chemical systems that support Darwinian evolution, we should be able to construct one of our own in the laboratory. If the NASA definition-theory of life is on point, this artificial system should be able to re-create all of the properties that we value in life. Conversely, if we cannot build life from scratch, then we must not understand completely what life is. Further, de novo synthesis provides us with candidate Darwinian molecules that are different in structure from those found in terran biology. Through syn- thesis, we can ask: What kinds of molecules other than standard DNA and RNA might support Darwinian evolution? This takes us in the direction of universality, at least as far as our imagination and synthetic technology allow. Underlying the famous double helix of Watson and Crick (Watson and Crick 1953) are two simple rules for genetics, rules that describe complementarity between two DNA strands.

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  Foundations for Sustainability

  A Coherent Framework of Life–Environment Relations

  • Daniel A. Fiscus, Brian D. Fath(Authors)
  • 2018(Publication Date)
  • Academic Press

    (Publisher)

  Chapter 4

  Life

  From origins to humans

  Abstract

  With holistic science strategies and framing in mind–intentional modeling and drawing of system boundaries, awareness of how values and assumptions alter science impacts, etc.–in this chapter we apply the holistic and anticipatory approach to study the origin of Life. We also review existing approaches to answering the question “What is Life?” and offer our holistic contribution to this recurring and provocative question. We propose that both of these fundamental Life science topics are relevant and can yield practical results for solving the present day and real-world sustainability challenge.

  Keywords

  Holistic Life science; origin of Life; what is Life?; relational reasoning; unit-model of Life; holons; hexaflexgons

  In the last chapter, we looked at our choices related to drawing system boundaries, how those choices impact the results we get, and how values and assumptions play into our Life science. With these strategies and framing in mind, we next apply the holistic and anticipatory approach to study the origin of Life. After that, we review existing approaches to answering the question “What is Life?” and offer our holistic contribution to this recurring and provocative question.

  Holistic Perspective on the Origin of Life

  How does the holistic Life perspective alter attempts to develop hypotheses, models, scenarios, and narratives for the origin of Life? This is an important question, not only due to the perennial interest in the question, and the potent curiosity and basic science involved, but also due to the possibility that understanding the original and fundamental nature of Life may hold clues and keys to what we need to understand and change to live long and prosper as technologically advanced humans in socially developed nations and civilization. If that link—between the origin of Life and implications for actionable science to steer human progress—seems weak, then we hope you will read this next section with an open mind and consider that it may yield important fruits. This quote may serve for inspiration—a motto that at one time was posted on the Internet as the stated mission of the NASA Institute for Advanced Concepts (NIAC). The mission of NIAC was:

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  Life's Origin

  The Beginnings of Biological Evolution

  • J. William Schopf(Author)
  • 2002(Publication Date)
  • University of California Press

    (Publisher)

  New discoveries notwithstanding, it was the synergistic interaction of concepts proposed by two particularly creative scientists—Mendeleev in chemistry and Charles Darwin ( 1809–1882 ) in biology—that led Oparin to his idea of how life began. Oparin’s final scientific paper (Oparin 1986 ), published six years after his death, critically reviews various hypotheses of the origin of life. And his words still resonate: We can conclude that the different forms of life are not the result of a process having a determined finality developed a priori by a creative plan, nor are they the result of a chance fortuitous act. Life emerged as the result of natural evolutionary processes, as a new form of movement of matter during its process of development. The study of this process allows us to know, with a scientific base, the essence of life and its qualitative difference from the world of inorganic matter. In the late 1920 s, a hypothesis very similar to Oparin’s was developed independently by the English biologist J. B. S. Haldane. He and Oparin proposed that the origin of life on Earth was preceded by a period of nonbiological molecular evolution. The Oparin-Haldane hypothesis as-sumes that, during and after Earth’s formation, simple carbon com-pounds were transformed into increasingly more complex ones by means of heat and solar radiation. In addition, Oparin proposed that, after the production of organic compounds of fairly high molecular weight, a phase separation occurred, resulting in formation of micro-scopic organic droplets (colloidal coacervates ). These coacervates were 16 John Oró able to selectively accumulate simple organic compounds from the environment, thereby giving rise to chemically coupled reactions of in-creasing complexity—reactions that were, in important respects, simi-lar to those of living systems. This phase separation made primitive competition possible and established a type of natural selection among pre-life, protobiont droplets.

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