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There have been a number of proposals regarding the '''origin of life''' on earth.  However, the various proposals fall into two schools of thought.

There have been a number of proposals regarding the '''origin of life''' on earth.  However, the various proposals fall into two schools of thought.

One, held by [[Creationism|creationists]], is that life originated divinely/[[supernatural]]ly.

One, held by [[Creationism|creationists]], is that life originated divinely/[[supernatural]]ly.

The other school of thought is that non-life became life solely by means of natural processes.  This is commonly referred to as ''abiogenesis'' and "chemical [[evolution]]".<ref name="creationresearch.org">http://www.creationresearch.org/crsq/articles/36/36_4/abiogenesis.html</ref><ref>http://www.creationbc.org/index.php?option=com_content&view=article&id=86&Itemid=85</ref> Abiogenesis is only a hypothesis, not a developed or accepted scientific theory.<ref>Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032. Washington, DC: National Academies Press. 2023. ISBN 0309475783. "Studies of the chemical origins of life start with the hypothesis that mixtures of simple small molecules under the influence of various energy sources and early Earth environments created the building blocks of life and that interactions among these molecules eventually lead to life itself (Figure 12-2)."</ref><ref name="Luisi"/>  

The other school of thought is that non-life became life solely by means of natural processes.  This is commonly referred to as ''abiogenesis'' and "chemical [[evolution]]".<ref name="creationresearch.org">http://www.creationresearch.org/crsq/articles/36/36_4/abiogenesis.html</ref><ref>http://www.creationbc.org/index.php?option=com_content&view=article&id=86&Itemid=85</ref> Abiogenesis is only a hypothesis, not a developed or accepted scientific theory.<ref>Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032. Washington, DC: National Academies Press. 2023. ISBN 0309475783. "Studies of the chemical origins of life start with the hypothesis that mixtures of simple small molecules under the influence of various energy sources and early Earth environments created the building blocks of life and that interactions among these molecules eventually lead to life itself (Figure 12-2)."</ref><ref name="Luisi"/> High-profile evolutionists [[PZ Myers]] and Nick Matzke, agree that the origin of life is part of the evolutionary [[paradigm]], as does [[Richard Dawkins]].<ref name="Origin of life">[https://creation.com/origin-of-life Origin of life]</ref>

High-profile evolutionists [[PZ Myers]] and Nick Matzke, agree that the origin of life is part of the evolutionary [[paradigm]], as does [[Richard Dawkins]].<ref name="Origin of life">[https://creation.com/origin-of-life Origin of life]</ref>

There are two main classes of origin-of-life research: chemical synthesis and molecular assembly.<ref name="Tour"/> The transition from non-living to living has never been observed in the wild or in the laboratory.<ref name="Luisi"/> Nor has self organizing molecules to a living cell have ever been observed in the wild or in a laboratory either.<ref name="Tour"/>

Committees for the National Academies of Science have observed that chemists have held skeptical views of abiogenesis because of extensive laboratory experience indicating that there are numerous chemical problems that inhibit nature, which has no direction or goal, from synthesizing any complex biochemical molecules that are needed for cellular life to even emerge.<ref name="NAS">Committee on the Limits of Organic Life in Planetary Systems; Committee on the Origins and Evolution of Life (2007). The Limits of Organic Life in Planetary Systems. National Academies Press. pp. 58–60. ISBN 978-0309104845. "Chemists’ objection to the notion that life is a natural consequence of organic reactivity is simple and comes from broadly based empirical experience in organic-chemistry laboratories. Addition of energy to mixtures of organic species makes the mixtures more complex and less likely to support life. Shapiro has provided a thoughtful and detailed discussion of the difficulties. Briefly summarized, it suggests that existing prebiotic chemistry experiments do not offer plausible hypotheses for routes to complex biomolecules. In the complex chemical mixtures generated under prebiotic conditions, one may be able to find trace amounts of amino acids and perhaps nucleobases. Some might indeed catalyze reactions that have some utility. But other compounds may well inhibit catalysis or catalyze undesired reactions. For example, Joyce and Orgel pointed out that the clay-catalyzed condensation of nucleotides to yield small chains performed best, under the conditions that they considered, if only one enantiomer of the starting material was present. If both were present, the desired reaction with the desired enantiomer might be inhibited by the other enantiomer. Furthermore, the combination of any bifunctional molecule into an information-bearing polymer would be expected to be terminated at an early stage by the presence of an excess of molecules that bear only one functionality. Even crystallization, a well-documented method of obtaining order through self-organization, is not a particularly powerful way to separate mixtures of organic chemicals into their constituents. Normally, an organic compound must be relatively pure before crystallization occurs. That salts crystallize better may explain why crystals are more common in the mineral world than in the organic world. Even organic salts can have problems in crystallizing from an impure mixture. Those facts generate the central problem in prebiotic chemistry. Spontaneous self-organization is not known to be an intrinsic property of most organic matter, at least as observed in the laboratory. It can be driven only by an external source of free energy that is coupled to the organic system."</ref> Among the most common problems in prebiotic chemistry is the fact that origin of life research and experimentation relies on so much human intervention and fails to provide evidence for abiogenesis as a result of reliance on such frequent intervention.<ref name="Tour">James Tour, Charles B Thaxton, Walter L Bradley. 2020. The Mystery of Life's Origin. Discovery Press. ISBN 1936599740. 13. We're Still Clueless About the Origin of Life</ref><ref name="Richert">Richert, C. Prebiotic chemistry and human intervention. Nature Communications 9, 5177 (2018). https://doi.org/10.1038/s41467-018-07219-5</ref>  

Committees for the National Academies of Science have observed that chemists have held skeptical views of abiogenesis because of extensive laboratory experience indicating that there are numerous chemical problems that inhibit nature, which has no direction or goal, from synthesizing any complex biochemical molecules that are needed for cellular life to even emerge.<ref name="NAS">Committee on the Limits of Organic Life in Planetary Systems; Committee on the Origins and Evolution of Life (2007). The Limits of Organic Life in Planetary Systems. National Academies Press. pp. 58–60. ISBN 978-0309104845. "Chemists’ objection to the notion that life is a natural consequence of organic reactivity is simple and comes from broadly based empirical experience in organic-chemistry laboratories. Addition of energy to mixtures of organic species makes the mixtures more complex and less likely to support life. Shapiro has provided a thoughtful and detailed discussion of the difficulties. Briefly summarized, it suggests that existing prebiotic chemistry experiments do not offer plausible hypotheses for routes to complex biomolecules. In the complex chemical mixtures generated under prebiotic conditions, one may be able to find trace amounts of amino acids and perhaps nucleobases. Some might indeed catalyze reactions that have some utility. But other compounds may well inhibit catalysis or catalyze undesired reactions. For example, Joyce and Orgel pointed out that the clay-catalyzed condensation of nucleotides to yield small chains performed best, under the conditions that they considered, if only one enantiomer of the starting material was present. If both were present, the desired reaction with the desired enantiomer might be inhibited by the other enantiomer. Furthermore, the combination of any bifunctional molecule into an information-bearing polymer would be expected to be terminated at an early stage by the presence of an excess of molecules that bear only one functionality. Even crystallization, a well-documented method of obtaining order through self-organization, is not a particularly powerful way to separate mixtures of organic chemicals into their constituents. Normally, an organic compound must be relatively pure before crystallization occurs. That salts crystallize better may explain why crystals are more common in the mineral world than in the organic world. Even organic salts can have problems in crystallizing from an impure mixture. Those facts generate the central problem in prebiotic chemistry. Spontaneous self-organization is not known to be an intrinsic property of most organic matter, at least as observed in the laboratory. It can be driven only by an external source of free energy that is coupled to the organic system."</ref> Among the most common problems in prebiotic chemistry is the fact that origin of life research and experimentation relies on so much human intervention and fails to provide evidence for abiogenesis as a result of reliance on such frequent intervention.<ref name="Tour">James Tour, Charles B Thaxton, Walter L Bradley. 2020. The Mystery of Life's Origin. Discovery Press. ISBN 1936599740. 13. We're Still Clueless About the Origin of Life</ref><ref name="Richert">Richert, C. Prebiotic chemistry and human intervention. Nature Communications 9, 5177 (2018). https://doi.org/10.1038/s41467-018-07219-5</ref>  

#Laboratory experience from centuries of organic chemistry indicate that cross contamination of impure reactants and products in the natural world inhibit further formation of more complex biomolecules from simple ones, separation of necessary compounds generally does not occur in nature, any functional molecule that could even form would get terminated by the majority of nonfunctional material it emerged from, and self-organization is not a intrinsic property of biological matter.<ref name="NAS" />

#Laboratory experience from centuries of organic chemistry indicate that cross contamination of impure reactants and products in the natural world inhibit further formation of more complex biomolecules from simple ones, separation of necessary compounds generally does not occur in nature, any functional molecule that could even form would get terminated by the majority of nonfunctional material it emerged from, and self-organization is not a intrinsic property of biological matter.<ref name="NAS" />

#The '''water paradox''' is the chemical reality that water is essential for life and yet it destroys cellular components (e.g. proteins, enzymes and nucleic acids such as DNA and RNA).<ref name="water paradox" />

#The '''water paradox''' is the chemical reality that water is essential for life and yet it destroys cellular components (e.g. proteins, enzymes and nucleic acids such as DNA and RNA).<ref name="water paradox" />

#'''Chicken or the Egg problem regarding [[DNA]] and [[protein]]s''': John Horgan wrote: "Many investigators now consider nucleic acids to be much more plausible candidates for the first self-replicating [[molecule]]s. The work of [[James Watson|Watson]] and [[Francis Crick|Crick]] and others has shown that proteins are formed according to the instructions coded in DNA. But there is a hitch. DNA cannot do its work, including forming more DNA, without the help of catalytic proteins, or [[enzyme]]s. In short, proteins cannot form without DNA, but neither can DNA form without proteins. To those pondering the origin of life, it is a classic chicken-and-egg problem: Which came first, proteins or DNA?" - (John Horgan,[science writer], "In The Beginning...," ''[[Scientific American]]'', Vol. 264, No. 2, February 1991, pp.&nbsp;100–109, p.&nbsp;103)"<ref name="members.iinet.net.au"/>

#'''Chicken or the Egg problem regarding [[DNA]] and [[protein]]s''': John Horgan wrote: "Many investigators now consider nucleic acids to be much more plausible candidates for the first self-replicating [[molecule]]s. The work of [[James Watson|Watson]] and [[Francis Crick|Crick]] and others has shown that proteins are formed according to the instructions coded in DNA. But there is a hitch. DNA cannot do its work, including forming more DNA, without the help of catalytic proteins, or [[enzyme]]s. In short, proteins cannot form without DNA, but neither can DNA form without proteins. To those pondering the origin of life, it is a classic chicken-and-egg problem: Which came first, proteins or DNA?" - (John Horgan,[science writer], "In The Beginning...," ''[[Scientific American]]'', Vol. 264, No. 2, February 1991, pp.&nbsp;100–109, p.&nbsp;103)"<ref name="members.iinet.net.au"/>

#Complexity of the [[cell]]: [[Molecule|Molecular]] [[biology|biologist]] Michael Denton wrote regarding the complexity of the cell: "To grasp the reality of life as it has been revealed by [[molecular biology]], we must magnify a [[cell]] a thousand million times until it is twenty [[kilometer]]s in diameter and resembles a giant airship large enough to cover a great city like [[London]] or [[New York City|New York]]. What we would then see would be an object of unparalleled complexity and adaptive design. On the surface of the cell we would see millions of openings, like the port holes of a vast space ship, opening and closing to allow a continual stream of materials to flow in and out. If we were to enter one of these openings we would find ourselves in a world of supreme technology and bewildering complexity... Is it really credible that random processes could have constructed a reality, the smallest element of which-a functional [[protein]] or [[gene]] - is complex beyond our own creative capacities, a reality which is the very antithesis of chance, which excels in every sense anything produced by the intelligence of man?"<ref>Michael Denton, Evolution: A Theory in Crisis, Burnett Books, London, 1985, pages 328 and 342</ref>

#Complexity of the [[cell]]: [[Molecule|Molecular]] [[biology|biologist]] Michael Denton wrote regarding the complexity of the cell: "To grasp the reality of life as it has been revealed by [[molecular biology]], we must magnify a [[cell]] a thousand million times until it is twenty [[kilometer]]s in diameter and resembles a giant airship large enough to cover a great city like [[London]] or [[New York City|New York]]. What we would then see would be an object of unparalleled complexity and adaptive design. On the surface of the cell we would see millions of openings, like the port holes of a vast space ship, opening and closing to allow a continual stream of materials to flow in and out. If we were to enter one of these openings we would find ourselves in a world of supreme technology and bewildering complexity... Is it really credible that random processes could have constructed a reality, the smallest element of which-a functional [[protein]] or [[gene]] - is complex beyond our own creative capacities, a reality which is the very antithesis of chance, which excels in every sense anything produced by the intelligence of man?"<ref>Michael Denton, Evolution: A Theory in Crisis, Burnett Books, London, 1985, pages 328 and 342</ref>