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Origins of Life: Molecules and Natural Selection
paper back no dust jacket present. 229 pages. tight binding, although inside second page binding glue is exposed. limited markings or creasing- previous owner's name written on inside second page, and top of pages. limited chipping or tearing to edges.
232 pages, Hardcover
First published January 1, 1973
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January 5, 2025
A WORK FOR NONPROFESSIONALS, INTERESTED IN THESE TOPICS
British chemist Leslie Orgel (1927-2007) wrote in the Preface to this 1973 book, “This book is not written for professional biologists or chemists, but rather for college or advanced high school students and general readers who have a limited background in chemistry or biology… studies of the origin of life have recently progressed to a point at which it is possible to propose plausible mechanisms for most of the steps in the evolution of living organisms from the inorganic constituents of the primitive earth. There are, of course, enormous gaps in our knowledge but I believe that the origins of life can now be discussed fruitfully within the framework of modern chemistry and evolutionary biology. The extension of the discussion to life on other planets is straightforward, but necessarily very speculative.”
He recounts that Pasteur’s work was “very widely believed to have shown that spontaneous generation is not a universal, contemporary process. They helped to raise the question of the origins of life in its modern form for the first time.” (Pg. 11), He continues, “little important work on the origins of life was carried out in the period immediately following the revolutionary publications of Pasteur and Darwin. Experimental work was largely restricted to fruitless attempts to prove that microorganisms can be produced in special environments, for example, in organic material subjected to the influence of radium… A large and influential group did not believe that life could have evolved spontaneously and accepted either explicitly or implicitly the need for supernatural intervention. It may not be an accident that the next major step forward was taken in a society that had deliberately adopted a materialistic philosophy and was actively antireligous… in Russia [by] A.I. Oparin.” (Pg. 14)
He cautions, “Pre-Cambrian fossils and modern algae look very much alike... Chemical fossils … are found in fossil-bearing rocks … that derive from the original organisms… Unfortunately much of the evidence is still very controversial, so while on the whole it supports the idea that biochemistry has changed little since the early Pre-Cambrian, it would be wise to reserve judgment until more evidence is available.” (Pg. 28)
He asserts, “The occurrence of occasional errors in the replication of DNA is the only source of variety in those bacteria for which sexual processes are unimportant… It is interesting to compare mutations with errors made in setting the type for a book… a new and quite unanticipated meaning may result from an error. The change from ‘the comforts of immortality’ to ‘the comforts of immorality’ in a religious tract is a striking example of a deletion.” (Pg. 58)
He explains, “all CLOSED chemical systems ultimately run downhill to equilibrium. Living systems somehow escape this fate. This once led some authors to believe that living systems are guided by some ‘vital force’ that enables them to evade the laws of thermodynamics. The situation is now realized to be much simpler. Living organisms are not CLOSED systems, so the laws of thermodynamics in their standard form do not require that they run downhill to equilibrium.” (Pg. 75)
He asks, “At an early stage in the evolution of life, before the development of protein synthesis, no activating enzymes which [have] highly specific catalytic activity could have existed. How could polynucleotides have directed the synthesis of polypeptides, before the evolution of the activating enzymes? This is one of the great puzzles of evolutionary biology…” (Pg. 85)
He discusses in an Appendix the concept of Panspermia: “according to which life did not evolve from inorganic matter on earth, but reached us fully developed in the form of a bacterial spore that had escaped from a distant planet. The theory, as originally proposed, had mystic overtones, but the idea that life evolved elsewhere in the universe and then infected the earth is not in itself unreasonable… It seems certain that no spores could survive the journey from another solar system to the earth… If a living cell escaped from another planet within a meteorite, there is no reason to doubt that it could have survived the journey to the earth… The assumption that life was brought to the earth from another planet would deserve more attention if it made it easier to understand how life evolved… I think it more likely that a unique [genetic] code evolved on the earth than that life reached us from another planet. However, the latter point of view … should be entertained by students of the origins of life, at least on sleepless nights. Could life have been implanted on the earth, deliberately, by the members of a technological society on another planet?” (Pg. 94-95) (See Francis Crick’s later book, ‘Life Itself,’ for a description of how Orgel became more receptive to the concept of Panspermia later on.)
He analyzes the famous Miller/Urey experiment: “Some features of [Stanley] Miller’s experiments are clearly unrealistic: the oceans, for example, were not boiling at the time when life evolved. Miller chose to work with boiling water rather than a cold ‘ocean’ for technical reasons; otherwise the gases in the apparatus would not have circulated quickly enough… The most striking feature of Miller’s results was the discovery that several of the natural amino acids were formed in substantial amounts… Miller’s work stimulated many further efforts to understand the organic chemistry that occurred on the primitive earth. It was soon discovered that similar sets of organic molecules, including amino acids, are formed whenever a reducing mixture of gases is heated strongly enough… there is little reason to doubt that if the atmosphere was reducing, many of the twenty natural amino acids would have accumulated on the primitive earth.” (Pg. 126-129)
He states, “The genetic code, from a very early stage in its evolution on, must have been a three-letter code. There is no obvious reason why a two-letter or four-letter code should not have evolved on the primitive earth. However, no transition from an advanced two- or four-letter code to a three-letter code would have been possible. Such a transition would have led to a disastrous misinterpretation of all the genetic information that had been accumulated by natural selection. We do not understand much about the later stages in the evolution of the code. Somehow, an inaccurate system must have pulled itself up by its bootstraps…We do not know whether the structure of the genetic code is a historical accident or not… Theories of the later stages in the evolution of the genetic code are not described here since they are all so highly speculative. Experimental work on this problem is beginning in several laboratories. Hopefully, we shall soon be able to report some progress.” (Pg. 157-158)
He suggests, “Consider two models of the evolution of life on the primitive earth. First suppose that the evolution of a self-replicating system was a very improbable event… the first self-replicating system would have had ample time to eat up the prebiotic soup before any competitor could have gotten started. Once the prebiotic soup was used up, there was no longer any possibility of a second, independent origin of life… Next consider…[that] self-replicating systems arose with high probability. Then, roughly equal numbers of… organisms … would have competed with ... each other… [One type] could only have eliminated their competitors by ‘discovering’ one or more new adaptions that gave them a very pronounced selective advantage and allowed them to outgrow their mirror image competitors. Perhaps we shall never know… just what happened three billion or more years ago … The evolution of optimal specificity was just part of the more general process of the establishment of biological order.” (Pg. 167)
He acknowledges, “Why are we tempted to use … ‘loaded’ words when describing what, after all, are only the consequences of errors in the process of nucleic acid replication? One view, the only correct one, points out that when biologists make statements that seem to involve design or purpose they are using convenient abbreviations… Although this is the formally correct answer, it will not satisfy everyone. It is genuinely surprising that an organism that has evolved by random mutation and selection appears to be designed. The idea is contrary to intuition. It is true, but to many it will always remain ridiculous.” (Pg. 182)
He notes, “The evidence available at present does not indicate whether the evolution of biological systems is likely or not. We will not be able to decide until we know much more about the first steps in the evolution of life… Many writers have taken a more optimistic view of this problem, and some have claimed that life is almost certain to evolve in a suitable environment. They believe… it is almost sure to have evolved on other earth-like planets. However, this seems to be an incorrect conclusion, based on a misunderstanding of probability theory.” (Pg. 223)
He admits, “The major intellectual problem presented by the origins of life is concerned with the next stage, the evolution of biological organization. How did a complex and self-replicating organism evolve from an unorganized mixture of polymeric molecules? Little experimental evidence is available, so one is forced to attempt a speculative reconstruction of this phase in the origins of life.” (Pg. 230)
Though fifty years old, this book will still be of interest to those studying the origin of life on earth.
British chemist Leslie Orgel (1927-2007) wrote in the Preface to this 1973 book, “This book is not written for professional biologists or chemists, but rather for college or advanced high school students and general readers who have a limited background in chemistry or biology… studies of the origin of life have recently progressed to a point at which it is possible to propose plausible mechanisms for most of the steps in the evolution of living organisms from the inorganic constituents of the primitive earth. There are, of course, enormous gaps in our knowledge but I believe that the origins of life can now be discussed fruitfully within the framework of modern chemistry and evolutionary biology. The extension of the discussion to life on other planets is straightforward, but necessarily very speculative.”
He recounts that Pasteur’s work was “very widely believed to have shown that spontaneous generation is not a universal, contemporary process. They helped to raise the question of the origins of life in its modern form for the first time.” (Pg. 11), He continues, “little important work on the origins of life was carried out in the period immediately following the revolutionary publications of Pasteur and Darwin. Experimental work was largely restricted to fruitless attempts to prove that microorganisms can be produced in special environments, for example, in organic material subjected to the influence of radium… A large and influential group did not believe that life could have evolved spontaneously and accepted either explicitly or implicitly the need for supernatural intervention. It may not be an accident that the next major step forward was taken in a society that had deliberately adopted a materialistic philosophy and was actively antireligous… in Russia [by] A.I. Oparin.” (Pg. 14)
He cautions, “Pre-Cambrian fossils and modern algae look very much alike... Chemical fossils … are found in fossil-bearing rocks … that derive from the original organisms… Unfortunately much of the evidence is still very controversial, so while on the whole it supports the idea that biochemistry has changed little since the early Pre-Cambrian, it would be wise to reserve judgment until more evidence is available.” (Pg. 28)
He asserts, “The occurrence of occasional errors in the replication of DNA is the only source of variety in those bacteria for which sexual processes are unimportant… It is interesting to compare mutations with errors made in setting the type for a book… a new and quite unanticipated meaning may result from an error. The change from ‘the comforts of immortality’ to ‘the comforts of immorality’ in a religious tract is a striking example of a deletion.” (Pg. 58)
He explains, “all CLOSED chemical systems ultimately run downhill to equilibrium. Living systems somehow escape this fate. This once led some authors to believe that living systems are guided by some ‘vital force’ that enables them to evade the laws of thermodynamics. The situation is now realized to be much simpler. Living organisms are not CLOSED systems, so the laws of thermodynamics in their standard form do not require that they run downhill to equilibrium.” (Pg. 75)
He asks, “At an early stage in the evolution of life, before the development of protein synthesis, no activating enzymes which [have] highly specific catalytic activity could have existed. How could polynucleotides have directed the synthesis of polypeptides, before the evolution of the activating enzymes? This is one of the great puzzles of evolutionary biology…” (Pg. 85)
He discusses in an Appendix the concept of Panspermia: “according to which life did not evolve from inorganic matter on earth, but reached us fully developed in the form of a bacterial spore that had escaped from a distant planet. The theory, as originally proposed, had mystic overtones, but the idea that life evolved elsewhere in the universe and then infected the earth is not in itself unreasonable… It seems certain that no spores could survive the journey from another solar system to the earth… If a living cell escaped from another planet within a meteorite, there is no reason to doubt that it could have survived the journey to the earth… The assumption that life was brought to the earth from another planet would deserve more attention if it made it easier to understand how life evolved… I think it more likely that a unique [genetic] code evolved on the earth than that life reached us from another planet. However, the latter point of view … should be entertained by students of the origins of life, at least on sleepless nights. Could life have been implanted on the earth, deliberately, by the members of a technological society on another planet?” (Pg. 94-95) (See Francis Crick’s later book, ‘Life Itself,’ for a description of how Orgel became more receptive to the concept of Panspermia later on.)
He analyzes the famous Miller/Urey experiment: “Some features of [Stanley] Miller’s experiments are clearly unrealistic: the oceans, for example, were not boiling at the time when life evolved. Miller chose to work with boiling water rather than a cold ‘ocean’ for technical reasons; otherwise the gases in the apparatus would not have circulated quickly enough… The most striking feature of Miller’s results was the discovery that several of the natural amino acids were formed in substantial amounts… Miller’s work stimulated many further efforts to understand the organic chemistry that occurred on the primitive earth. It was soon discovered that similar sets of organic molecules, including amino acids, are formed whenever a reducing mixture of gases is heated strongly enough… there is little reason to doubt that if the atmosphere was reducing, many of the twenty natural amino acids would have accumulated on the primitive earth.” (Pg. 126-129)
He states, “The genetic code, from a very early stage in its evolution on, must have been a three-letter code. There is no obvious reason why a two-letter or four-letter code should not have evolved on the primitive earth. However, no transition from an advanced two- or four-letter code to a three-letter code would have been possible. Such a transition would have led to a disastrous misinterpretation of all the genetic information that had been accumulated by natural selection. We do not understand much about the later stages in the evolution of the code. Somehow, an inaccurate system must have pulled itself up by its bootstraps…We do not know whether the structure of the genetic code is a historical accident or not… Theories of the later stages in the evolution of the genetic code are not described here since they are all so highly speculative. Experimental work on this problem is beginning in several laboratories. Hopefully, we shall soon be able to report some progress.” (Pg. 157-158)
He suggests, “Consider two models of the evolution of life on the primitive earth. First suppose that the evolution of a self-replicating system was a very improbable event… the first self-replicating system would have had ample time to eat up the prebiotic soup before any competitor could have gotten started. Once the prebiotic soup was used up, there was no longer any possibility of a second, independent origin of life… Next consider…[that] self-replicating systems arose with high probability. Then, roughly equal numbers of… organisms … would have competed with ... each other… [One type] could only have eliminated their competitors by ‘discovering’ one or more new adaptions that gave them a very pronounced selective advantage and allowed them to outgrow their mirror image competitors. Perhaps we shall never know… just what happened three billion or more years ago … The evolution of optimal specificity was just part of the more general process of the establishment of biological order.” (Pg. 167)
He acknowledges, “Why are we tempted to use … ‘loaded’ words when describing what, after all, are only the consequences of errors in the process of nucleic acid replication? One view, the only correct one, points out that when biologists make statements that seem to involve design or purpose they are using convenient abbreviations… Although this is the formally correct answer, it will not satisfy everyone. It is genuinely surprising that an organism that has evolved by random mutation and selection appears to be designed. The idea is contrary to intuition. It is true, but to many it will always remain ridiculous.” (Pg. 182)
He notes, “The evidence available at present does not indicate whether the evolution of biological systems is likely or not. We will not be able to decide until we know much more about the first steps in the evolution of life… Many writers have taken a more optimistic view of this problem, and some have claimed that life is almost certain to evolve in a suitable environment. They believe… it is almost sure to have evolved on other earth-like planets. However, this seems to be an incorrect conclusion, based on a misunderstanding of probability theory.” (Pg. 223)
He admits, “The major intellectual problem presented by the origins of life is concerned with the next stage, the evolution of biological organization. How did a complex and self-replicating organism evolve from an unorganized mixture of polymeric molecules? Little experimental evidence is available, so one is forced to attempt a speculative reconstruction of this phase in the origins of life.” (Pg. 230)
Though fifty years old, this book will still be of interest to those studying the origin of life on earth.
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