[Home] [Site map] [Updates] [Projects] [Contents; 1. Introduction; 2. Philosophy (1), (2), (3), (4) & (5); 3. Religion (1) & (2); 4. History (1), (2) & (3); 5. Science; 6. Environment (1), (2) & (3); 7. Origin of life (1) & (3); 8. Cell & Molecular (1), (2) & (3); 9. Mechanisms (1), (2) & (3); 10. Fossil Record; 11. `Fact' of Evolution; 12. Plants; 13. Animals; 14. Man (1) & (2); 15. Social; 16. Conclusion; Notes; Bibliography A-C, D-F, G-I, J-M, N-S, T-Z]
"PROBLEMS OF EVOLUTION": 7. ORIGIN OF LIFE (2) 1. Evolutionists have no explanation for the origin of life 2. Problems of Miller-Urey experiments 3. The problem of the naturalistic origin of life 4. Problems for all naturalistic origin of life theories 5. Problems of origin of life approaches 1. Chance 2. Spontaneous generation 3. Biochemical predestination 4. Natural selection 5. Protein first 1. Proteins cannot form spontaneously in water 6. DNA (deoxyribonucleic acid) first 7. RNA (ribonucleic acid) first 8. PNA (peptide nucleic acid) first 9. Clay first 6. Problems of origin of life locations 7. Life still cannot be synthesised in a laboratory 8. No evidence of extraterrestrial life 9. The more known about life, the harder it is to imagine how it arose
"PROBLEMS OF EVOLUTION": 7. ORIGIN OF LIFE 5. Problems of origin of life approaches 1. Chance The late Harvard biologist, George Wald, used to claim in the 1950's that the spontaneous origin of life could occur by chance, given enough time:"When we consider the spontaneous origin of a living organism, this is not an event that need happen again and again. It is perhaps enough for it to happen once. The probability with which we are concerned is of a special kind; it is the probability that an event occur at least once. To this type of probability a fundamentally important thing happens as one increases the number of trials. However improbable the event in a single trial, it becomes increasingly probable as the trials are multiplied. Eventually the event becomes virtually inevitable. For instance, the chance that a coin will not fall head up in a single toss is 1/2. The chance that no head will appear in a series of tosses is 1/2X 1/2X 1/2...as many times over as the number of tosses. In 10 tosses the chance that no head will appear is therefore 1/2 multiplied by itself 10 times, or 1/1,000. Consequently the chance that a head will appear at least once in 10 tosses is 999/1,000. Ten trials have converted what started as a modest probability to a near certainty. The same effect can be achieved with any probability, however small, by multiplying sufficiently the number of trials. ... The important point is that since the origin of life belongs in the category of at-least-once phenomena, time is on its side. However improbable we regard this event, or any of the steps which it involves, given enough time it will almost certainly happen at least once. And for life as we know it, with its capacity for growth and reproduction, once may be enough. Time is in fact the hero of the plot. The time with which we have to deal is of the order of two billion years. What we regard as impossible on the basis of human experience is meaningless here. Given so much time, the `impossible' becomes possible, the possible probable, and the probable virtually certain. One has only to wait: time itself performs the miracles." (Wald G., "The origin of life," Scientific American, Vol. 191, No. 2, August 1954, pp.45-53, pp.47-48)So Gould criticised Phillip E. Johnson for in his book, Darwin on Trial, raising "the old chestnut against a natural origin of earthly- life by arguing: "the possibility that such a complex entity could assemble itself by chance is fantastically unlikely." Sure, and no scientist has used that argument for 20 years, now that we understand so much more about the self-organizing properties of molecules and other physical systems" (Gould 1992, p.93; Johnson, 1991, pp.103-104). Yet Dawkins only six years earlier in 1986, had argued just that:"So, cumulative selection can manufacture complexity while single-step selection cannot. But cumulative selection cannot work unless there is some minimal machinery of replication and replicator power, and the only machinery of replication that we know seems too complicated to have come into existence by means of anything less than many generations of cumulative selection! ... in this chapter we are asking how improbable, how miraculous, a single event we are allowed to postulate. What is the largest single event of sheer naked coincidence, sheer unadulterated miraculous luck, that we are allowed to get away with in our theories, and still say that we have a satisfactory explanation of life? In order for a monkey to write 'Methinks it is like a weasel' by chance, it needs a very large amount of luck, but it is still measurable. We calculated the odds against it as about 10 thousand million million million million million million (1040) to 1 against. Nobody can really comprehend or imagine such a large number, and we just think of this degree of improbability as synonymous with impossible. ... So, there are some levels of sheer luck, not only too great for puny human imaginations, but too great to be allowed in our hard-headed calculations about the origin of life. ... The answer to our question - of how much luck we are allowed to postulate - depends upon whether our planet is the only one that has life, or whether life abounds all around the universe. The one thing we know for certain is that life has arisen once, here on this very planet. ... There are probably at least 1020 (i.e. 100 billion billion) roughly suitable planets in the universe. ... Let us, for the sake of discussion, entertain the alternative assumption that life has arisen only once, ever, and that was here on Earth. ... if we assume, as we are perfectly entitled to do for the sake of argument, that life has originated only once in the universe, it follows that we are allowed to postulate a very large amount of luck in a theory, because there are so many planets in the universe where life could have originated. ... let us put an upper limit of 1 in 100 billion billion for the maximum amount of luck that this argument entitles us to assume. Think about what this means. We go to a chemist and say: get out your textbooks and your calculating machine; sharpen your pencil and your wits; fill your head with formulae, and your flasks with methane and ammonia and hydrogen and carbon dioxide and all the other gases that a primeval nonliving planet can be expected to have; cook them all up together; pass strokes of lightning through your simulated atmospheres, and strokes of inspiration through your brain; bring all your clever chemist's methods to bear, and give us your best chemist's estimate of the probability that a typical planet will spontaneously generate a self-replicating molecule. Or, to put it another way, how long would we have to wait before random chemical events on the planet, random thermal jostling of atoms and molecules, resulted in a self-replicating molecule? Chemists don't know the answer to this question. Most modern chemists would probably say that we'd have to wait a long time by the standards of a human lifetime, but perhaps not all that long by the standards of cosmological time. The fossil history of earth suggests that we have about a billion years - one 'aeon', to use a convenient modern definition - to play with, for this is roughly the time that elapsed between the origin of the Earth about 4.5 billion years ago and the era of the first fossil organisms. But the point of our 'numbers of planets' argument is that, even if the chemist said that we'd have to wait for a 'miracle', have to wait a billion billion years - far longer than the universe has existed, we can still accept this verdict with equanimity. There are probably more than a billion billion available planets in the universe. If each of them lasts as long as Earth, that gives us about a billion billion billion planet-years to play with. That will do nicely! A miracle is translated into practical politics by a multiplication sum." (Dawkins, 1986b, pp.141-145)But as New York University chemistry professor and origin of life specialist, Robert Shapiro noted, "The Skeptic will want to rewrite Professor Wald's conclusion: Improbability is in fact the villain of the plot" as "The improbability involved in generating even one bacterium is so large that it reduces all considerations of time and space to nothingness" :"We are now ready to handle the chances for the spontaneous generation of a bacterium. ... For our purposes, we will want to overestimate and select the largest number of random trials that might have been attempted on the early earth, as the actual number would be very difficult to determine. We need to know two items, the length of time needed for a single trial and the number of trials that can take place simultaneously. Under the most favorable conditions, an E. coli colony can double in about twenty minutes. In other words, it takes twenty minutes for a bacterium to assemble a replica of itself from simple chemicals. It is unlikely that a bacterium would come together more quickly by random processes. Let us presume, however, that a simpler bacterium than E. coli is involved, and estimate one minute as the time for a trial. If we accept the evidence of the fossils and the usual age cited for the solar system, then a maximum of 1 billion years, or 5 x 1014 minutes, was available for the origin of life on earth. What about available space? As a maximum estimate, we can assume that the entire earth was covered by an ocean 10 kilometers deep, which was available for experiments. Further, we will allow that space to be divided into small compartments (1 micrometer on each side) of bacterial size. We would then have 5 times 1036 separate reaction flasks. If a separate try was made in each flask every minute for 1 billion years, we would have 2.5 times 1051 tries available. ... As a rough rule, we will consider that an event becomes probable when the number of trials available is of the same order of magnitude ... as the adverse odds on a single trial. ... We cannot compute these odds precisely, but approximations will serve our purposes quite well. ... A more realistic estimate has been made by Harold Morowitz, a Yale University physicist. He has calculated the odds for the following case: Suppose we were to heat up a large batch of bacteria in a sealed container to several thousand degrees, so that every chemical bond within them was broken .... We then cooled this mixture slowly, in order to allow the atoms to form new bonds, until everything came to equilibrium. In this state, the most stable chemicals (those with the least energy) would dominate the mixture, while those with higher energy would be present to a lesser extent, in accordance with the laws of statistics. Morowitz asks, what fraction of the final product will consist of living bacteria? Or in other words, if a single bacterium was used to start the experiment (ensuring that the appropriate atoms, in proper amounts, were present), what would be the chances that a living bacterium would result at the end? The answer computed by Morowitz reduces the odds of Hoyle [1 in 1040,000] to utter insignificance: 1 chance in 10100,000,000,000. ... This number is so large that to write it in conventional form we would require several hundred thousand blank books. We would enter "1" on the first page of the first book, and then fill it, and the remainder of the books, with zeros. ... The Skeptic will want to rewrite Professor Wald's conclusion: Improbability is in fact the villain of the plot. The improbability involved in generating even one bacterium is so large that it reduces all considerations of time and space to nothingness. Given such odds, the time until the black holes evaporate and the space to the ends of the universe would make no difference at all. If we were to wait, we would truly be waiting for a miracle." (Shapiro, 1986, pp.125-128)See Holtz, Robert L., "Probing the Chemistry of Creation," Los Angeles Times, May 15, 1997."Now how difficult would it be to put together the replicator at random? The minimal published estimates of its size propose a single strand of RNA of perhaps 20 nucleotides. To build this structure, about 600 atoms would have to be connected in a specific way, much less than the many millions needed for a bacterium. ... But what are the odds? J.B.S. Haldane recognized that the chances of obtaining a self- replicating machine depended on the number of parts to it. If the number was small, there was no problem: "By mere shuffling you will get the letters ACEHIMN to spell 'machine' once in 5040 trials on an average." If you could shuffle at the rate of once per second, it would require only 84 minutes to run that many tries. This analogy suggests that it should not be hard to put together a smallish replicator, so we must look more closely at it. We will stay with the metaphor of language, but set aside the letters on cards in favor of another much-used situation: the monkey at the typewriter. Let's call him Charlie the Chimp. Charlie is special. He never gets tired, and types out one line per second, completely at random. ... Now let us give Charlie a normal keyboard with, say, 45 keys. The odds suddenly escalate to 1 in 457, or 1 in 370 billion tries. It would take Charlie (or his descendants) 11,845 years to run that many attempts. The word "machine" does not arise as readily as Haldane's first analogy would suggest. Things get rapidly worse when we use longer messages. We will let Charlie try for a bit of Hamlet. The phrase "to be or not to be" has 18 characters, if we count the spaces as characters. The chances that our chimp will type this out are 1 in 4518, or 1 in 6 x 109. At one try per second, it will take poor Charlie more than 1022 years to do that number of tries. Should the open model for the universe be correct, Charlie will still be typing away long after the stars have ceased to shine and all the planets have been dispersed into space through stellar near- collisions. But now we have developed a real thirst for Shakespeare. We want our monkey to type out "to be or not to be: that is the question," which has 40 characters. The chances then become 4540, or about 1066, to 1. This is a number 10 million times greater than the number of trials maximally available for the random generation of a replicator on the early earth. There we have it. If the chances of getting the replicator at random from a prebiotic soup are less than that of striking "to be or not to be: that is the question" by chance on a typewriter, we had best forget it. The replicator would have about 600 atoms. The chances of Charlie typing a 600-letter message (twice the size of this paragraph) correctly are 1 in 10992." (Shapiro R., "Origins: A Skeptic's Guide to the Origin of Life," Summit Books: New York NY, 1986, pp.168-169)."The law of chance, as stated by Emile Borel, is that `events whose probability is extremely small never occur.' (Borel E., "Elements of the Theory of Probability," Prentice-Hall: Englewood Cliffs NJ, 1965, p.57). He defined `extremely small' as, on the cosmic scale, a probability of 1050 or smaller. .... In order to make this `single law of chance' more absolute in its certainty, Borel then did some interesting calculating, giving chance some inordinate concessions as we have done. The great French mathematician first considered matter as divided into the smallest possible atomic particles. To pack the universe, he said, would require no more than 10120 of these. Next he divided time into the smallest intervals on the scale of atomic processes and said that 1040 would be the total of these smallest intervals of time that could happen in billions of centuries, aiming at a generous approximation of the life span of the universe, including our solar system. Borel said that, if one considers collisions between these minuscule particles at the tremendous rapidity of such extremely short periods of time, then, by multiplying the two figures together, the total number of these infinitely small elementary phenomena does not exceed 10160 in the entire universe and during the longest period of time we can assign to the duration of our solar system. It is thus impossible to imagine that the simplest event could recur more than 10160 times ... This single law of chance, according to Borel, `carries with it a certainty of another nature than mathematical certainty... it is comparable even to the certainty which we attribute to the existence of the external world. [Borel E., "Probabilities and Life," Dover: New York, 1962, p.6]" (Coppedge J.F.,"Evolution: Possible or Impossible?," Zondervan: Grand Rapids MI, 1973, p.231)."One final point about probabilistic resources is important here to note. In the observable universe, probabilistic resources come in very limited supplies. Within the known physical universe there are estimated around 1080 elementary particles. Moreover, the properties of matter are such that transitions from one physical state to another cannot occur at a rate faster than 1045 times per second. This frequency corresponds to the Planck time, which constitutes the smallest physically meaningful unit of time. Finally, the universe itself is about a billion times younger than 1025 (assuming the universe is between ten and twenty billion years old). seconds assume that If we now any specification of an event within the known physical universe requires at least one elementary particle to specify it and cannot be generated any faster than the Planck time, then these cosmological constraints imply that the total number of specified events throughout cosmic history cannot exceed 1080 x 1045 x 1025 = 10150. It follows that any specified event of probability less than 1 in 10150 will remain improbable even after all conceivable probabilistic resources from the observable universe have been factored in. A probability of 1 in 10150 is therefore a universal probability bound. A universal probability bound is impervious to all available probabilistic resources that may be brought against it. indeed, all the probabilistic resources in the known physical world cannot conspire to render remotely probable an event whose probability is less than this universal probability bound. The universal probability bound of 1 in 10150 is the most conservative in the literature. The French mathematician Emile Borel proposed 1 in 1050 as a universal probability bound below which chance could definitively be precluded (i.e., any specified event as improbable as this could never be attributed to chance). Cryptographers assess the security of cryptosystems in terms of a brute force attack that employs as many probabilistic resources as are available in the universe to break a cryptosystem by chance. In its report on the role of cryptography in securing the information society, the National Research Council set 1 in 1094 as its universal probability bound to ensure the security of cryptosystems against chance-based attacks. As we shall see ... such levels of improbability are easily attained by real physical systems. It follows that if such systems are also specified, then they are designed." (Dembski W.A., "No Free Lunch: Why Specified Complexity Cannot Be Purchased without Intelligence," Rowman & Littlefield: Lanham MD, 2002, pp.21-22. Emphasis in original)."It is clear that the belief that a molecule of iso-1-cytochrome c or any other protein could appear by chance is based on faith. And so we see that even if we believe that the 'building blocks' are available, they do not spontaneously make proteins, at least not by chance. The origin of life by chance in a primeval soup is impossible in probability in the same way that a perpetual motion machine is impossible in probability. The extremely small probabilities calculated in this chapter are not discouraging to true believers (Hoffer, 1951) or to people who live in a universe of infinite extension that has no beginning or end in time. In such a universe all things not streng verboten will happen. In fact we live in a small, young universe generated by an enormous hydrogen bomb explosion some time between 10 x 109 and 20 x 109 years ago. A practical person must conclude that life didn't happen by chance (de Duve, 1991)." (Yockey H.P., "Information Theory and Molecular Biology," Cambridge University Press: Cambridge UK, 1992, p.257)."Even in the simple case of a bacterium, the genome consists of some 4 x 106 nucleotides, and the number of combinatorially possible sequences is 44 million = 102.4 million The expectation probability for the nucleotide sequence of a bacterium is thus so slight that not even the entire space of the universe would be enough to make the random synthesis of a bacterial genome probable. For example, the entire mass of the universe, expressed as a multiple of the mass of the hydrogen atom, amounts to about 1080 units. Even if all the matter in space consisted of DNA molecules of the structural complexity of the bacterial genome, with random sequences, then the chances of finding among them a bacterial genome or something resembling one would still be completely negligible. It can naturally be objected that our statistical arguments are based upon the assumption of an entity with the complexity of a bacterial genome, while the historical process of the origin of life possibly took place by way of simpler forms of life. However, an appropriate analysis, based on probability theory, shows that not even an optimised enzyme molecule can arise in a random synthesis. Even the smallest catalytically active protein molecules of the living cell consist of at least a hundred amino acid residues, and they thus already possess more than 10130 sequence alternatives ... These striking numerical examples allow us to conclude with Monod that the design of a primitive organism has about the same chance of arising by pure chance, in a molecular roulette, as a general textbook of biochemistry has of arising by the random mixing of a sufficient number of letters." (Kuppers B-O., "Information and the Origin of Life," , MIT Press: Cambridge MA, 1990, reprint, p.60)[top] 2. Spontaneous generation"One can ask for nothing better in such a pass than a noisy and stubborn opponent, and this Pasteur had in the naturalist Felix Pouchet, whose arguments before the French Academy of Sciences drove Pasteur to more and more rigorous experiments. When he had finished, nothing remained of the belief in spontaneous generation. We tell this story to beginning students of biology as though it represents a triumph of reason over mysticism. In fact it is very nearly the opposite. The reasonable view was to believe in spontaneous generation; the only alternative, to believe in a single, primary act of supernatural creation. There is no third position. For this reason many scientists a century ago chose to regard the belief in spontaneous generation as a `philosophical necessity.' It is a symptom of the philosophical poverty of our time that this necessity is no longer appreciated. Most modern biologists, having reviewed with satisfaction the downfall of the spontaneous generation hypothesis, yet unwilling to accept the alternative belief in special creation, are left with nothing." (Wald G., "The origin of life," Scientific American, Vol. 191, No. 2, August 1954, pp.45-53, pp.45-46)[top] 3. Biochemical predestination"When most of us think of the controversy over evolution in the public schools, we are likely to think of fundamentalists pulling teachers from their classrooms and placing them in the dock. Images from the infamous Scopes "monkey" trial of 1925 come to mind. Unfortunately, intolerance of this sort has shown itself in California in the 1990s as a result of students complaining about a biology instructor. Unlike the original Scopes case, however, thiscase involves a distinguished biology professor at a major university -- indeed, an acknowledged expert on evolutionary theory. Also unlike Scopes, the teacher was forbidden to teach his course not because he taught evolutionary theory (which he did) but because he offered a critical assessment of it. The controversy first emerged last fall after Dean Kenyon, a biology professor at San Francisco State University, was ordered not to teach "creationism" by John Hafernik, the chairman of his biology department. Mr. Kenyon, who included three lectures in biological origins in his introductory course, had for many years made a practice of exposing students to both evolutionary theory and evidence uncongenial to it. He also discussed the philosophical controversies raised by the issue and his own view that living systems display evidence of intelligent design -- a view not incompatible with some forms of evolutionary thinking. Mr. Hafernik accused Mr. Kenyon of teaching what he characterized as biblical creationism and ordered him to stop. After Mr. Hafernik's decree, Mr. Kenyon asked for clarification. He wrote the dean, Jim Kelley, asking what exactly he could not discuss. Was he "forbidden to mention to students that there are important disputes among scientists about whether or not chemical evolution could have taken place on the ancient earth?" Mr. Kelley replied by insisting that Mr. Kenyon "teach the dominant scientific view," not the religious view of "special creation on a young earth." Mr. Kenyon replied again (I paraphrase): I do teach the dominant view. But I also discuss problems with the dominant view and that some biologists see evidence of intelligent design. He received no reply. Instead, he was yanked from teaching introductory biology and reassigned to labs. There are several disturbing aspects to this story: First, Mr. Kenyon is an authority on chemical evolutionary theory and the scientific study of the origin of life. He has a Ph.D. in biophysics from Stanford and is the co-author of a seminal theoretical work titled "Biochemical Predestination" (1969). The book articulated what was arguably the most plausible evolutionary account of how a living cell might have organized itself from chemicals in the "primordial soup." Mr. Kenyon's subsequent work resulted in numerous scientific publications on the origin-of-life problem. But by the late 1970s, Mr. Kenyon began to question some of his own earlier ideas. Experiments (some performed by Mr. Kenyon himself) increasingly contradicted the dominant view in his field. Laboratory work suggested that simple chemicals do not arrange themselves into complex information- bearing molecules such as DNA -- without, that is, "guidance" from human experimenters. To Mr. Kenyon and others, such results raised important questions about how "naturalistic" the origin of life really was. If undirected chemical processes cannot produce the coded strands of information found in even the simplest cells, could perhaps a directing intelligence have played a role? By the 1980s, Mr. Kenyon had adopted the second view." (Meyer S.C., "Danger: Indoctrination: A Scopes Trial for the '90s," The Wall Street Journal, December 6, 1993. Access Research Network, December 29, 1998. http://www.arn.org/docs/meyer/sm_scopes.htm)[top] 4. Natural selection Natural selection cannot be invoked to explain the origin of life (Maynard Smith, 1975, pp.110-111; Ambrose, 1990, p.95)."One way out of the problem would be to extend the concept of natural selection to the pre-living world of molecules. A number of authors have entertained this possibility, although no reasonable explanation has made the suggestion plausible. Natural selection is a recognized principle of differential reproduction which presupposes the existence of at least two distinct types of self-replicating molecules. Dobzhansky appealed to those doing origin-of-life research not to tamper with the definition of natural selection when he said: `I would like to plead with you, simply, please realize you cannot use the words `natural selection' loosely. Prebiological natural selection is a contradiction in terms.' [Dobzhansky T.G., in Fox S.W., ed., "The Origins of Prebiological Systems and of Their Molecular Matrices," Academic Press: New York NY, 1965, p.310] Bertalanffy made the point even more cogently: `Selection, i.e., favored survival of "better" precursors of life, already presupposes self-maintaining, complex, open systems which may compete; therefore selection cannot account for the origin of such systems' [von Bertalanffy L., "Robots, Men and Minds," George Braziller: New York NY, 1967, p.82]" (Thaxton C.B., Bradley W.L. & Olsen R.L., "The Mystery of Life's Origin: Reassessing Current Theories," , Lewis & Stanley: Dallas TX, 1992, p.147) [top]5. Protein first 1. Proteins cannot form spontaneously in water"Joining amino acids into a growing protein chain requires energy and the removal of a water molecule (the removal of an -OH group from the end of the chain and an -H from the incoming amino acid). Therefore this cannot occur spontaneously in a watery environment, such as a primordial `soup'" (Raven & Johnson, 1995, p.69). [top] ]6. DNA (deoxyribonucleic acid) first"Living cells rely on three things: DNA, to store an accurate copy of protein-making instructions, RNA, to take those instructions to the protein-making parts of the cell, and special proteins called enzymes to get the protein- making process to work (Matthews, 1992, p.60). So which came first: DNA, RNA or proteins (since it would be a miracle for even two of them to arise in the same place at the same time together)? If DNA is opted for by evolutionists, then they encounter "the ultimate chicken-and-egg problem in biology: DNA contains the instructions for building proteins, but it needs certain proteins - enzymes in the first place to carry out its task of passing on that information." (Matthews, 1992, p.60). [top]"The implausibility of prevital nucleic acid. If it is hard to imagine polypeptides or polysaccharides in primordial waters it is harder still to imagine polynucleotides. But so powerful has been the effect of Miller's experiment on the scientific imagination that to read some of the literature on the origin of life (including many elementary texts) you might think that it had been well demonstrated that nucleotides were probable constituents of a primordial soup and hence that prevital nucleic acid replication was a plausible speculation based on the results of experiments. There have indeed been many interesting and detailed experiments in this area. But the importance of this work lies, to my mind, not in demonstrating how nucleotides could have formed on the primitive Earth, but in precisely the opposite: these experiments allow us to see, in much greater detail than would otherwise have been possible, just why prevital nucleic acids are highly implausible. Let us consider some of the difficulties. First, as we have seen, it is not even clear that the primitive Earth would have generated and maintained organic molecules. All that we can say is that there might have been prevital organic chemistry going on, at least in special locations. Second, high- energy precursors of purines and pyrimidines had to be produced in a sufficiently concentrated form (for example at least 0.01 M HCN). Third, the conditions must now have been right for reactions to give perceptible yields of at least two bases that could pair with each other. Fourth, these bases must then have been separated from the confusing jumble of similar molecules that would also have been made, and the solutions must have been sufficiently concentrated. Fifth, in some other location a formaldehyde concentration of above 0.01 M must have built up. Sixth, this accumulated formaldehyde had to oligomerise to sugars. Seventh, somehow the sugars must have been separated and resolved, so as to give a moderately good concentration of, for example, D-ribose. Eighth, bases and sugars must now have come together. Ninth, they must have been induced to react to make nucleosides. (There are no known ways of bringing about this thermodynamically uphill reaction in aqueous solution: purine nucleosides have been made by dry-phase synthesis, but not even this method has been successful for condensing pyrimidine bases and ribose to give nucleosides (Orgel & Lohrmann, 1974).) Tenth, whatever the mode of joining base and sugar it had to be between the correct nitrogen atom of the base and the correct carbon atom of the sugar. This junction will fix the pentose sugar as either the a- or ß-anomer of either the furanose or pyranose forms (see page 29). For nucleic acids it has to be the ß-furanose. (In the dryphase purine nucleoside syntheses referred to above, all four of these isomers were present with never more than 8 % of the correct structure.) Eleventh, phosphate must have been, or must now come to have been, present at reasonable concentrations. (The concentrations in the oceans would have been very low, so we must think about special situations - evaporating lagoons and such things (Ponnamperuma, 1978).) Twelfth, the phosphate must be activated in some way - for example as a linear or cyclic polyphosphate - so that (energetically uphill) phosphorylation of the nucleoside is possible. Thirteenth, to make standard nucleotides only the 5'- hydroxyl of the ribose should be phosphorylated. (In solid-state reactions with urea and inorganic phosphates as a phosphorylating agent, this was the dominant species to begin with (Lohrmann & Orgel, 1971). Longer heating gave the nucleoside cyclic 2',3'-phosphate as the major product although various dinucleotide derivatives and nucleoside polyphosphates are also formed (Osterberg, Orgel & Lohrmann, 1973).) Fourteenth, if not already activated - for example as the cyclic 2',3'- phosphate - the nucleotides must now be activated (for example with polyphosphate; Lohrmann, 1976) and a reasonably pure solution of these species created of reasonable concentration. Alternatively, a suitable coupling agent must now have been fed into the system. Fifteenth, the activated nucleotides (or the nucleotides with coupling agent) must now have polymerised. Initially this must have happened without a pre-existing polynucleotide template (this has proved very difficult to simulate (Orgel & Lohrmann, 1974)); but more important, it must have come to take place on pre-existing polynucleotides if the key function of transmitting information to daughter molecules was to be achieved by abiotic means. This has proved difficult too. Orgel & Lohrmann give three main classes of problem. (i) While it has been shown that adenosine derivatives form stable helical structures with poly(U) - they are in fact triple helixes - and while this enhances the condensation of adenylic acid with either adenosine or another adenylic acid mainly to di(A) - stable helical structures were not formed when either poly(A) or poly(G) were used as templates. (ii) It was difficult to find a suitable means of making the internucleotide bonds. Specially designed watersoluble carbodiimides were used in the experiments described above, but the obvious pre-activated nucleotides - ATP or cyclic 2',3'-phosphates - were unsatisfactory. Nucleoside 5'-phosphorimidazolides, for example ... were more successful, but these now involve further steps and a supply of imidazole, for their synthesis (Lohrmann & Orgel, 1978). (iii) Internucleotide bonds formed on a template are usually a mixture of 2'-5' and the normal 3'-5' types. Often the 2'-5' bonds predominate although it has been found that Zn2+, as well as acting as an efficient catalyst for the template-directed oligomerisation of guanosine 5'-phosphorimidazolide also leads to a preference for the 3'-5' bonds (Lohrmann, Bridson & Orgel, 1980). Sixteenth, the physical and chemical environment must at all times have been suitable - for example the pH, the temperature, the M2+ concentrations. Seventeenth, all reactions must have taken place well out of the ultraviolet sunlight; that is, not only away from its direct, highly destructive effects on nucleic acid-like molecules, but away too from the radicals produced by the sunlight, and from the various longer lived reactive species produced by these radicals. Eighteenth, unlike polypeptides, where you can easily imagine functions for imprecisely made products (for capsules, ion-exchange materials, etc.), a genetic material must work rather well to be any use at all otherwise it will quickly let slip any information that it has managed to accumulate. Nineteenth, what is required here is not some wild one-off freak of an event: it is not true to say `it only had to happen once'. A whole set-up had to be maintained for perhaps millions of years: a reliable means of production of activated nucleotides at the least. Now you may say that there are alternative ways of building up nucleotides, and perhaps there was some geochemical way on the early Earth. But what we know of the experimental difficulties in nucleotide synthesis speaks strongly against any such supposition. However it is to be put together, a nucleotide is too complex and metastable a molecule for there to be any reason to expect an easy synthesis. You might want to argue about the nineteen problems that I chose: and I agree that there is a certain arbitrariness in the sequence of operations chosen. But if in the compounding of improbabilities nineteen is wrong as a number that would be mainly because it is much too small a number. If you were to consider in more detail a process such as the purification of an intermediate you would find many subsidiary operations - washings, pH changes and so on. (Remember Merrifield's machine: for one overall reaction, making one peptide bond, there were about 90 distinct operations required.)" (CairnsSmith A.G., "Genetic Takeover and the Mineral Origins of Life," , Cambridge University Press: Cambridge UK, 1987, reprint, p.56-59. Emphasis in original)"In Genetic Takeover I listed 14 major hurdles that would have to be overcome for primed nucleotides to have been made on the primitive Earth - from the build-up of sufficient and separate concentrations of formaldehyde and cyanide to the final 'winding-up' of the nucleotides. In practice each of these processes would be subdivided into separate unit operations that would have to be suitably sequenced. In carrying out an organic synthesis in the laboratory there are tens or hundreds of little events: lifting, pouring, mixing, stirring, topping-up, decanting, adjusting etc., etc. There may not be much to these unit operations in themselves, but their sequencing has to be right. There is a manufacturing procedure that has to be followed, and when such a procedure is at all prolonged it becomes absurd to imagine it being carried out by chance. That is why simple amino acids are plausible probiotic products, primed nucleotides are not. It is not that one cannot imagine plausible unit processes on the primitive Earth that, taken together, might have yielded primed nucleotides - as one can imagine a coin falling heads a thousand times in a row. Yes, you can imagine the primitive Earth doing the kinds of things that the practical organic chemist does. you can see a pool evaporating in the sun to concentrate a solution, or two solutions happening to mix because a stream overflows, or a catalytic mineral dust being blown in by the wind. you can imagine filtrations, decantations, beatings, acidifications: you can imagine many such operations taking place through little geological and meteorological accidents. But to show that each step in a sequence is plausible is not to show that the sequence itself is plausible. But, you may say, with all the time in the world, and so much world, the right combinations of circumstances would happen some time? Is that not plausible? The answer is no: there was not enough time, and there was not enough world. Let me try to justify this. It would be a safe oversimplification, I think, to say that on average the 14 hurdles that I referred to in the making of primed nucleotides would each take 10 unit operations - that at least 140 little events would have to be appropriately sequenced. (If you doubt this, go and watch an organic chemist at work; look at all the things he actually does in bringing about what he would describe as 'one step' in an organic synthesis.) And it is surely on the optimistic side to suppose that, unguided, the appropriate thing happened at each point on one occasion in six. But if we take this as the kind of chance that we are talking about, then we can say that the odds against a successful unguided synthesis of a batch of primed nucleotide on the primitive Earth are similar to the odds against a six coming up every time with 140 throws of a dice. Is that sort of thing too much of a coincidence or not? There are 6 possible outcomes from throwing a dice once; 6 x 6 from a double throw; 6 x 6 x 6 from a triple throw; and 6 multiplied by itself 140 times from 140 throws. This is a huge number, represented approximately by a 1 followed by 109 zeros (i.e. ~ 10109). This is the sort of number of trials that you would have to make to have a reasonable chance of hitting on the one outcome that represents success. Throwing one dice once a second for the period of the Earth's history would only let you get through about 1015 trials: so you would need about 1094 dice. That is far more than the number of electrons in the observed Universe (estimated at around 1080). Of course you might argue that in practice a synthesis might be carried through in different ways, and that is true, but remember what generous allowances we made in cutting down the actual amount of sheer skill that organic synthesis requires. And remember 48 Seven clues to the origin of life too that a manufacturing procedure is not usually very forgiving about arbitrary modifications: it all too easily goes off the rails never to recover. This is especially true of chemical processes, where it is usually not good enough to add the acid at the wrong time or throw away the wrong solution, or even use an ultraviolet lamp of the wrong sort. Careless organic synthesis only works when the product that is wanted belongs to that inevitably small set of molecules that are especially stable - molecules like carbon dioxide and water, even perhaps glycine and adenine in a much more limited way. But nucleotides are not like that to judge from the price. One's intuition can lead one astray when thinking of the role of vast times and spaces in generating improbable structures. The moral is that vast times and spaces do not make all that much difference to the level of competence that pure chance can simulate. Even to get 14 sixes in a row (with one dice following the rules of our game) you should put aside some tens of thousands of years. But for 7 sixes a few weeks should do, and for 3 sixes a few minutes. This is all an indication of the steepness of that cliff-face that we were thinking about: a three-step process may be easily attributable to chance while a similar thirty-step process is quite absurd." (Cairns-Smith A.G., "Seven Clues to the Origin of Life: A Scientific Detective Story," , Cambridge University Press: Cambridge UK, 1993, reprint, pp.46-48)7. RNA (ribonucleic acid) first It was later discovered that some RNA molecules could perform limited rearrangement of other RNA molecules, act somewhat like an enzymes, hence their name "ribozymes" (Matthews, 1992, p.60). But unfortunately for evolutionists, RNA is an extremely complex molecule, that is hard to construct out of ingredients thought to exist on the early Earth (Matthews, 1992, p.60), and store in the optimal conditions of a modern laboratory, with purified ingredients, using high intelligence and advanced technology (Matthews, 1992, p.60). It is even "harder still to get RNA to copy itself," which after all, is "the key requirement" (Matthews, 1992, p.60)!"`It is probably only a matter of time, to be measured in years rather than decades, before a self-sustained RNA evolving system can be demonstrated in the laboratory. This would be a case in which a DNA-and protein-based life form, namely a human biochemist, gives rise to an RNA-based life form, an interesting reversal of the sequence of events that occurred during the early history of life on Earth.' [Joyce G.F., "The RNA World: Life Before DNA and Protein," in Zuckerman B. & Hart M.H., eds., "Extraterrestrials Where Are They?" Cambridge University Press: Cambridge UK, Second edition.,1995, pp.139-151] When that event takes place, the media will probably announce it as the demonstration of a crucial step in the origin of life. I would agree, with one modification. The concept that the scientists are illustrating is one of intelligent design. No better term can be applied to a quest in which chemists are attempting to prepare a living system in the laboratory, using all the ingenuity and technical resources at their disposal. Whether they use synthetic chemicals or materials isolated from nature, we would be justified in calling the living system artificial or human-made life." (Shapiro R., "Planetary Dreams: The Quest to Discover Life beyond Earth," John Wiley & Sons: New York NY, 1999, pp.102-104. My emphasis)."The search for ribozymes evokes the same feeling of achievement and beauty in me that I get when I see a skilled golfer playing a difficult course at well under par. To imagine that related events could take place on their own appears as likely as the idea that the golf ball could play its own way around the course without the golfer. We can, of course imagine that natural forces would lend a helping hand. A hurricane could move the ball down the course, and occasional floods might "putt" the ball into the hole. A small earthquake could then remove it and place it on the next tee. Perhaps each of these events could be simulated if we tried hard enough. But to insist that all of these events be linked together and move in an appropriate direction puts our origin into the realm of Morowitz's odds [10100,000,000,000 to 1]." (Shapiro R., "Planetary Dreams: The Quest to Discover Life beyond Earth," John Wiley & Sons: New York NY, 1999, p.104. My emphasis)."But one needed nucleotides, not amino acids, to construct DNA or RNA. I knew that nucleotides were far more intricate than the amino acids that Miller had produced. To form a nucleotide, you have to connect three different chemicals in a very specific way: If you wanted a building block for RNA, for example, you had to select one of four information units (bases): adenine, cytosine, guanine, or uracil, and attach it in an unusual way to the sugar, ribose. The product then had to be united with the mineral, phosphate, to form a nucleotide. In spite of these difficulties, RNA world advocates assumed that the early Earth provided an abundant supply of such substances. ... what the basis was for such optimism. Had Miller's experiments produced a bumper harvest of nucleotides in his simulated ocean? Had these substances been found in nonliving sources such as meteorites? ... No, they haven't been found there at all. But many chemists have shown that it's not a problem. They can make these compounds in their labs under `prebiotic conditions,' which mimic those of the early Earth. These scientists have tried to identify candidate chemical reactions that lead to RNA under conditions that may have existed on the early Earth. They run their reactions in water, avoid strong acids and alkalis, and use chemicals that they consider "prebiotic" for their experiments. To qualify as prebiotic, a chemical must appear in a Miller-Urey-type reaction or be produced in another `prebiotic' experiment. The scientists have assembled lists of such reactions, which they feel supports their general position. They admit that problems exist but feel that they can be solved by additional work on their part. As Jim Ferris stated, the pathway must have existed. The scientists' job is to locate the correct one. My own opinion has been very different: These reactions, while well carried out in most cases and often ingenious, have nothing whatsoever to do with the origin of life." (Shapiro R., "Planetary Dreams: The Quest to Discover Life beyond Earth," John Wiley & Sons: New York NY, 1999, pp.108-109. Emphasis in original)."Promising though the RNA world scenario seems, it has many detractors. They point out that, however good the theory may be, test tube experiments are frequently dismal failures. Key reactions stubbornly refuse to proceed without carefully designed procedures and the help of special catalysts. Nucleic acid chains are notoriously fragile, and tend to snap long before they have acquired the 50 or so base pairs needed for them to act as enzymes. Water attacks and breaks up nucleic acid polymers as it does peptides, casting doubt on any soupy version of an RNA world. Even the synthesis of the four bases required as building blocks is not without serious problems. As far as biochemists can see, it is a long and difficult road to produce efficient RNA replicators from scratch. No doubt a way could eventually be found for each step in the chemical sequence to be carried out in the lab without too much drama, but only under highly artificial conditions, using specially prepared and purified chemicals in lust the right proportions. The trouble is, there are very many such steps involved, and each requires different special conditions. It is highly doubtful that all these steps would obligingly happen one after the other 'in the wild', where a chemical soup or scum would just have to take pot luck. The conclusion has to be that without a trained organic chemist on hand to supervise, nature would be struggling to make RNA from a dilute soup under any plausible prebiotic conditions. So whilst an RNA world could conceivably function and evolve towards life if handed to us on a plate (perhaps in a soup bowl would be a better metaphor), getting the RNA world going from a crude chemical mixture is another matter entirely. Added to these diverse difficulties is the problem of chirality - left versus right ... The fact that all life on Earth is based on molecules with the same handedness is not merely a curiosity: RNA replication would be menaced in an environment in which both left- and right-handed versions of the basic molecules are equally present. The crucial lock-and-key templating arrangements, whereby bases pair up with complementary bases according to their shapes, would be compromised as molecules with the 'wrong' handedness locked into the slots. The left hand would mess up what the right hand was doing. Unless a way can be found for nature to create a soup with molecules of only one handedness, spontaneous RNA synthesis would be a lost cause. Proponents of the RNA world scenario have received flak not just from chemists but from biologists too. If life began with RNA replication, you would expect the necessary replication machinery to be very ancient, and therefore common to all extant life. However, genetic analysis reveals that the genes coding for RNA replication differ markedly in the three domains of life, suggesting that RNA replication was refined some time after the common ancestor lived. There has also been criticism on theoretical grounds. The RNA world theory focuses exclusively on replication at the expense of metabolism. As I have stressed already, life is about more than raw reproduction: living organisms also do things, and must do them if they are to survive to reproduce. Doing things costs energy. There has to be a ready source of energy for organisms to metabolize. In test-tube experiments, RNA molecules are lovingly supplied with specialized energetic chemicals to power their activities, but in nature RNA would have to make do with whatever was lying around. No Miller-Urey type experiment has succeeded in fabricating the energizing chemicals used by extant life: they are all manufactured inside cells. Spoon-fed RNA may be a slick replicator, but without an energy-liberating metabolic cycle already in place, these fecund genetic strands would soon become molecular drop-outs. An obvious escape route is to seek a self-replicating molecule far simpler than RNA to start the whole game going. The RNA world would then come only much later. It is conceivable that a relatively small molecule might be found that can replicate faithfully enough. The way would then lie open for molecular evolution to elaborate it, adding information step by step, until a level of complexity comparable to short strands of RNA was achieved. The system could then be 'taken over' by RNA. Is this how biogenesis really happened? Maybe. However, there are many obstacles to that theory, such as doubt over whether small a molecules can be accurate enough replicators to avoid the error catastrophe. In extant life, high- fidelity replication seems to be associated with large, complex systems. It is the larger genomes, with their and error-correcting procedures, that are the best copiers. So if the trend among nucleic acid replicators is followed down to smaller and smaller size, one expects only poor replication accuracy from simple molecules. Moreover, the smaller a molecule is, the more drastic will be the relative effect of any mutational change, and the greater the chance that the mutation won't inherit the property of itself being a replicator. In recent years, attempts have been made to build small and simple replicator molecules in the lab, and to subject them to environmental stresses to see if they evolve into better replicators. Modest success has been claimed. However, these experiments do not demonstrate molecular evolution in nature. They have yet to show that the sort of small replicators that have been painstakingly designed and fabricated in the laboratory will form spontaneously under plausible prebiotic conditions, and if they do, whether they will replicate well enough to evade the error catastrophe. In short, nobody has a clue whether naturally occurring mini-replicators are even possible, let alone whether they have got what it takes to evolve successfully." (Davies P.C.W., "The Fifth Miracle: The Search for the Origin of Life," Penguin: Ringwood Vic, Australia, 1998, pp.99-101. Emphasis in original)."It is this last function, the ability to self-replicate, that Joyce and Orgel call `the molecular biologists' dream:' If a truly self-replicating molecule could be produced in the laboratory, a huge gap in our understanding of the origin of life would be closed. ... Remarkable as the results from test-tube-evolution experiments are, these evolved ribozymes are still a very long way from the full realization of the molecular biologists' dream. Even the cleverest ribozyme yet produced can only copy short stretches of itself. It is very unlikely, we suspect, that a molecule can be selected for that could polymerize a copy of itself along its entire length without some kind of help. ... Let us assume for a moment that Orgel is correct and that sometime in the near future a researcher will tease out, from the large array of random RNA sequences lurking in a test tube, the one that has the ability to catalyze its own replication from simple components of the type found in the primordial soup. At this point, many researchers would argue that life has been created in the laboratory. But would this be a reenactment of the origin of life as it might have taken place on the early Earth? Certainly not! A much larger problem will remain: Even if researchers eventually do create such an astonishing molecule in the laboratory, this is no guarantee that a similar molecule would ever have been synthesized in the primordial soup or on rock surfaces early in the history of our planet." (Wills C.J. & Bada J.I., "The Spark of Life: Darwin and the Primeval Soup," , Oxford University Press: New York NY, 2001, reprint, pp.129-130) The RNA first approach entails that there were living organism(s) whose genetic system was RNA->protein which became today's universal DNA->RNA->protein. However Dawkins' argument against saltationist theories applies:"So far, this is a fine summary of the orthodox neo-Darwinian view. Now. in a bizarre passage, Kauffman goes on: `But this appears to be false. One of the wonderful and puzzling features of the Cambrian explosion is that the chart was filled up from the top down. Nature suddenly sprang forth with many wildly different body plans-the phyla - elaborating on these basic designs to form the classes, orders, families, and genera ... In his book about the Cambrian explosion, Wonderful Life: The Burgess Shale and the Nature of History, Stephen Jay Gould remarks on this top-down quality of the Cambrian with wonder.' [Kauffman S.A., "At Home in the Universe," 1996, p.13] As well he might! You only have to think for one moment about what `top down' filling in would have to mean for the animals on the ground and you immediately see how preposterous it is. 'Body plans' like the mollusc body plan, or the echinoderm body plan, are not ideal essences hanging in the sky, waiting, like designer dresses, to be adopted by real animals. Real animals is all there ever was: living, breathing, walking, eating, excreting, fighting, copulating real animals, who had to survive and who can't have been dramatically different from their real parents and grandparents. For a new body plan-a new phylum-to spring into existence, what actually has to happen on the ground is that a child is born which suddenly, out of the blue, is as different from its parents as a snail is from an earthworm. No zoologist who thinks through the implications, not even the most ardent saltationist, has ever supported any such notion. Ardent saltationists have been content to postulate the sudden bursting into existence of new species, and even that relatively modest idea has been highly controversial. When you spell out the Gouldian rhetoric into real-life practicalities, it stands revealed as the purest of bad poetic science." (Dawkins R., "Unweaving The Rainbow: Science, Delusion and the Appetite for Wonder," , Penguin: London, 1999, reprint, p.203. Emphasis in original)Yet a change from RNA->protein to DNA->RNA->protein would be a greater change than from "a snail" to "an earthworm", since snails and earthworms and bacteria too, all have a DNA->RNA->protein genetic system. Bearing in mind that there is no such thing as a `simple' living organism:"Protozoa are often erroneously referred to as `simple' organisms. There are no simple organisms. Many are exceedingly complex and are the most elaborately organized of all known cells. Protozoa carry on all the basic functions of multicellular animals and are amazingly efficient in the performance of these functions. Each is extremely well adapted to its own environment. They are widespread ecologically and are found in fresh, marine, and brackish water and in moist soils." (Hickman C.P. & Hickman F.M., "Laboratory Studies in Animal Diversity," McGraw-Hill: Boston MA, Third Edition, 1995, p.23)8. PNA (peptide nucleic acid) first"Because RNA is unstable and difficult to synthesize, the first genetic material may have used a simpler backbone than ribose. One candidate is peptide nucleic acid (PNA), in which the backbone is polymeric N- (2aminoethyl)glycine (AEG) and the N-acetic acids of the bases (N9 for purines, N1 for pyrimidines) are linked via amide bonds (Figure 1). This is an attractive scenario because AEG forms in spark-tube experiments that also produce amino acids ( ), and may spontaneously polymerize at 100°. The N-acetic acids of the bases are also accessible in prebiotic syntheses, which suggests that PNA could have been an early genetic material (although the evidence is far from conclusive)." (Knight R.D. & Landweber L.F., "The Early Evolution of the Genetic Code," Cell, Vol. 101, No. 6, 9 June 2000, pp.569-572. http://makeashorterlink.com/?H33C54CEA)"The Peptide-Nucleic Acid Proposal Several years ago, Stanley Miller (of spark-experiment fame) formally acknowledged the intractability of the problem of homochirality's origin. Consequently, he proposed that the first self-replicating molecules were the achiral peptide nucleic acids (PNA) 43 He was attracted to PNA molecules because they contain no sugars or phosphates and because they can form base pairs and helical structures just as DNA can. The nucleobases of PNA are joined together through a molecule of acetic acid and a non-naturally occurring achiral amino acid, 2-aminoethyl glycine (AEG). For a PNA origin-of-life option to be viable, an abundant prelife source of nucleobases, acetic acid, and AEG must be found. So far, a source has been identified only for the simplest of these molecules (acetic acid). AEG has not been detected in outer space sites or in the nonorganic terrestrial realm. Stanley Miller's team has made AEG in the laboratory, but the conditions have questionable relevance for early Earth A source of PNA either on Earth or in outer space at the time of life's origin, or a naturalistic pathway for adequate PNA production, also needs to be demonstrated. Perhaps most troubling, PNA molecules, once assembled, are stable-too stable. Highly reluctant to let go of the daughter molecules they may have duplicated, the reproduction of PNA would have been extremely slow, if it occurred at all. Scientists also have yet to demonstrate that PNAs can perform the variety of enzymatic activities that would drive evolution from a PNA world to an RNA world." (Rana F.R. & Ross H.N., "Origins of Life: Biblical And Evolutionary Models Face Off," Navpress: Colorado Springs CO, 2004 p.133)"A spontaneous origin for RNA can be judged very implausible, but never impossible. . If life started that way, we would expect life to be quite rare in the universe. ... I helped to launch this trend by pointing out the enormous difficulty in obtaining the sugar, ribose, in the prebiotic world. The case for ribose is even worse than the one for cytosine. Stanley Miller has contributed by measuring the stability of ribose. Even if it could be prepared successfully, half of it would decompose in 300 days at room temperature, as compared to 300 years for cytosine. For these reasons, many scientists have headed for the following escape hatch: Abandon ribose, but keep the idea of a replicator, so that natural selection can operate. Life then began with a simpler replicator, which functioned for a time in a pre-RNA world. At a certain point in evolution, it was replaced by RNA. The search for a suitable substitute replicator has become an exciting game, with several entrants in place. Swiss chemist Albert Eschenmoser ... found one surprising candidate. He had wanted to understand why ribose was the sugar of choice for the backbone of RNA, and also why ribose existed in a particular form, a five-membered ring, in RNA. Under other circumstances, ribose generally prefers to form an alternative sixmembered ring. Using enormous energy and ingenuity, Eschenmoser and his co-workers constructed a number of RNA alternatives, including one that contained ribose in a six-membered ring. Surprisingly, the chemical properties of the six-ring version suggested that it would be a better replicator than the natural RNA. But it is hard to see why, once it got installed, it would ever yield to RNA. I would rather think that RNA assumed its present role accidentally, after functioning for some other purpose in an already existing cell. Professor Eschenmoser has been very reluctant to place any such strong interpretation on his results, though he has given his creation a name, p-RNA; I prefer the name `Swiss RNA' because of its greater efficiency. Other alternatives exist. Stanley Miller prefers PNA, a combination of an amino acid backbone with the information units used by RNA. For this reason he has tried to sabotage ribose while rescuing cytosine. Others have suggested that even proteins themselves have an unrecognized ability to serve as the replicator. But I will argue that all replicators of this general type were very unlikely in the origin of life." (Shapiro R., "Planetary Dreams: The Quest to Discover Life beyond Earth," John Wiley & Sons: New York NY, 1999, pp.117-118) [top]9. Clay first"A.G. Cairns-Smith, a biochemist at the University of Glasgow, Scotland, hypothesizes that clays may have formed the first self-replicating structures. Cairns-Smith devised an elaborate theory which proposed that amino acids were concentrated by adsorption on clay. Cairns-Smith reasoned that because clay acts as an industrial catalyst, it served as a primitive catalyst in encouraging flawed crystals to form information content in carbon-chained molecules. He rejected the concept of a prebiotic soup and proposed that the first living organism resulted from the growth of one crystal on the surface of the lattice of another crystal. He called his theory of replicating clays the genetic takeover and proposed RNA as the takeover molecule. [Cairns-Smith A. G., "Genetic Takeover and the Mineral Origins of Life," Cambridge University Press: Cambridge UK, 1982] Cairns-Smith noted that the microcrystals of clay consist of a regular silicate lattice with a routine pattern of ionic locations but with deviated distribution of metals at those locations. He regarded the metal ions as carriers of information similar to the nucleotide basis in an RNA molecule. These ions can form irregular patterns of electrostatic potential which can adsorb molecules to the surfaces, and, as hypothesized by Cairns-Smith, perform the same function as RNA in a crude fashion. According to his theory, one day crystal discovered that RNA is a better genetic substance than clay, and RNA was formed. Cairns-Smith's theory falters in failing to explain complexity and in failing to distinguish between order and complexity. Again, complexity is the sine qua non of living matter. The distinction between living and non- living structures is in their complexity which is represented by the high information content found in living organisms. No experiment has produced anything like this complexity. Crystals are not a viable explanation for the origin of a mechanism which would generate sufficient information content into inert matter to produce the genome necessary for life. Although crystals are ordered with periodic arrangements of atoms, they carry very little information. Nucleic acids and proteins are information macromolecules with aperiodic structures arranged in a specified sequence. The specified sequence of the base sequence of a DNA molecule has an unpredictable pattern with flexibility which allows the conveyance of a vast amount of information. If DNA consisted of the same type of order as a crystal, it would only be capable of repeating a simple message over and over again. [Pearcey N.R. & Thaxton C.B., "The Soul of Science," Crossway Books: Wheaton, IL, 1994, p.238] DNA represents an entirely different type of order than the type of order found in a crystal. Highly ordered crystals are repetitive in structure. They are similar to the old story of a law student who had too little sleep and too much caffeine and wrote the same sentence over and over again on every line of his examination book. His examination essay was very ordered and very redundant. Redundancy is the main characteristic of crystal structure, but complex sequences and information are characteristics of life forms. The distinction between order and complexity is-well delineated in information theory which emphasizes the quantification and measurement of information content. A crystal has a highly ordered structure but low intelligence or information content. The DNA molecule has a high information content with a complicated set of instructions for the assembly of the organism. It has complexity. Crystal structures may be highly ordered, but have a low information content and do not have complexity. In regarding the crystal imperfections as the source of the RNA, DNA and enzyme system, Cairns-Smith is "grossly mistaken" in his hypothesis that the information density in a crystallite is at all similar to the information content in DNA. [Yockey H.P., "Self Organization Origin of Life Scenarios and Information Theory," Journal of Theoretical Biology, Vol. 91, 1981, p.14] Ex arena funiculum nectis. ["You are weaving a rope of sand"] A large chasm exists between the simple instructions required for crystalline order and the vast number of instructions contained in DNA: `To describe a crystal, one would need only specify the substance to be used and the way in which the molecules were packed together. A couple of sentences would suffice, followed by the instructions "and keep on doing the same," since the packing sequence in a crystal is regular .... It would be quite impossible to produce a correspondingly simple set of instructions that would enable a chemist to synthesize the DNA of an E. coli bacterium. In this case, the sequence matters. Only by specifying the sequence letter-by-letter (about 4,000,000 instructions) could we tell a chemist what to make. Our instructions would occupy not a few short sentences, but a large book instead!' [Thaxton C.B., Bradley W.L. & Olsen R.L., "The Mystery of Life's Origin: Reassessing Current Theories," , Lewis & Stanley: Dallas TX, 1992, p.131] Hubert Yockey also rejects the crystal imperfection hypothesis on the basis of information theory: `The transfer of information from clay surfaces to organic macromolecules that is presumed to be a pseudo- DNA/RNA/protein system is mathematically impossible, not just unlikely, if the entropies of the two probability spaces are not equal. To say that crystal life is a modified perfection while molecular life is a tamed chaos is merely a play on words.... The clay scenario is one of the attempts to use the "order" that is characteristic of a crystal as an analogue of the "order" that is supposed to characterize informational biomolecules ... The progression of the sequences derived from clay to proteins is essentially the same process conceived in the origin of life by chance.... Therefore, for this reason also, the clay scenario provides no pathway from the crystal imperfections in clay particles to information biomolecules.' [Yockey H.P., "Information Theory and Molecular Biology," Cambridge University Press: Cambridge UK, 1992, p.236]" (Overman D.L., "A Case Against Accident and Self-Organization," Rowman & Littlefield: Lanham MD, 1997, p.77) [top]
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