The Origin of Life and the Death of Materialism
The Intercollegiate Review 31, no. 2
April 1, 1996
Alfred North Whitehead once said that "when we consider what religion is for mankind and what science is, it is no exaggeration to say that the future course of history depends upon the decision of this generation as to the relations between them." Whitehead spoke early in this century at a time when most elite intellectuals believed that science contradicted classical theism with its traditional belief in a divine creation, the uniqueness of man and the immortality of the human soul. For many intellectuals a scientifically-informed world view was a materialistic world view in which the mere mention of entities such as God, free will, mind, soul or purpose seemed inherently disreputable. Materialism denied evidence of any intelligent design in nature and any ultimate purpose to human existence. As Whitehead's contemporary Bertrand Russell put it, "man is the product of causes which had no prevision of the end they were achieving" and which predestine him "to extinction in the vast death of the solar system."
It is not hard to see why many intellectuals held this opinion. Despite the now-well documented influence of Christian thinking on the rise of modern science from the time of Ockham to Newton, much of science during the 19th century did take a decidedly materialistic turn. Scientific origins theories in particular seemed to support the materialistic vision of an autonomous and self-creating natural world. For example, at the beginning of the 19th century the French mathematician Laplace offered an ingenious theory known as the nebular hypothesis to account for the origin of the solar system as the outcome of purely natural gravitational forces. In geology, Charles Lyell explained the origin of the earth's most dramatic topographical features--mountain ranges and canyons--as the result of slow, gradual and completely naturalistic processes of change. Most significantly, Darwin's evolutionary theory sought to show that the blind process of natural selection acting on random variations could, and did, account for the origin of new forms of life without any divine intervention or guidance. According to Darwin, living organisms only appeared to be designed by an intelligent creator; nature itself was the real creator. Even in cosmology, a belief in the infinity of space and time obviated any need to consider the question of the ultimate origin of matter. Thus, for scientific materialists at the end of the nineteenth century, the whole history of the universe and life could be told as a seamless‚ or nearly seamless, unfolding of the potentiality of matter and energy. No longer could it be held that a pre-existent mind shaped matter. Rather, modern science showed that matter shaped and created the capacities of mind (and not the reverse). God did not create "the heavens and the earth." The heavens and the earth (i.e., matter) created (via evolution) the minds that created the concept of God.
By the turn of the twentieth century, this once shockingly materialistic approach to science had become the norm. Most twentieth century scientists have assumed no limits to the explanatory power of materialistic forces. Materialistic modes of thought and assumptions have spread from physics and biology to psychology, sociology, criminology, economics, educational theory, and even theology. Thus, Whitehead would in the end attempt to reconcile science and religion by asserting that even God himself evolves.
Yet now at the end of the twentieth century after many wars and genocidal policies pursued in the name of materialistic "science-based" ideologies, the scientific picture of the world is rapidly changing. From the microcosm of the cell and the quantum world, to the macrocosm of an expanding and finely-tuned universe, the materialistic vision of nature now seems incomplete. Even in biology where Darwin's theory, perhaps more than any other, inspired the possibility of a fully materialistic world view, materialism now seems to be failing as scientists have uncovered an awe-inspiring complexity in even the simplest of living cells. Indeed, nowhere is the inadequacy of materialistic science more evident than in the contemporary discussion of how life in its very "simplest" form might have first originated.
The Problem of Life's Origin
After Darwin published the Origin of Species in 1859, many scientists began to think about a problem that Darwin had not addressed, namely, how life had arisen in the first place. While Darwin's theory purported to explain how life could have grown gradually more complex starting from "one or a few simple forms," it did not explain, nor did it attempt to explain, where life had first originated. Indeed, by the 1870s with Darwin's theory of the origin of species, Laplace's nebular hypothesis, and Lyellian geology enjoying widespread support, the origin of life remained as the only salient milestone in cosmic history lacking some materialistic explanation.
Yet, scientists in the 1870s and 1880s assumed that devising an explanation for the origin of life would be fairly easy. For one thing, they assumed that life was essentially a rather simple substance called protoplasm that could be easily constructed by combining and recombining simple chemicals such as carbon dioxide, oxygen and nitrogen. Thus, the German evolutionary biologist Ernst Haeckel would refer to the cell as a simple "homogeneous globule of plasm." To Haeckel a living cell seemed no more complex than a blob of jello. His theory of how life first came into existence reflected this simplistic view. His method likened cell "autogony," as he called it, to the process of inorganic crystallization. Haeckel's English counterpart, T.H. Huxley, proposed a simple two-step method of chemical recombination to explain the origin of the first cell. Just as salt could be produced spontaneously by adding sodium to chloride, so, thought Haeckel and Huxley, could a living cell be produced by adding several chemical constituents together and then allowing spontaneous chemical reactions to produce the simple protoplasmic substance that they assumed to be the essence of life.
Orthodox Chemical Evolutionary Theory: The Oparin Scenario
During the 1920s and 1930s a more sophisticated version of this so-called "chemical evolutionary theory" was proposed by a Russian biochemist named Alexander I. Oparin. Oparin had a much more accurate understanding of the complexity of cellular metabolism, but neither he, nor any one else in the 1930s, fully appreciated the complexity of the molecules such as protein and DNA that make life possible. Oparin, like his nineteenth century predecessors, suggested that life could have first evolved as the result of a series of chemical reactions. Unlike his predecessors, however, he envisioned that this process of chemical evolution would involve many more chemical transformations and reactions and many hundreds of millions (or even billions) of years.
Oparin's theory envisioned a series of chemical reactions (See Figure 1) that he thought would enable a complex cell to assemble itself gradually and naturalistically from simple chemical precursors. Oparin believed that simple gases such as ammonia (NH3), methane (CH4), water (H20), carbon dioxide (CO2) and hydrogen (H2) would have rained down to the early oceans and combined with metallic compounds extruded from the core of the earth. With the aid of ultraviolet radiation from the sun, the ensuing reactions would have produced energy-rich hydrocarbon compounds. These in turn would have combined and recombined with various other compounds to make amino acids, sugars, phosphates and other "building blocks" of the complex molecules (such as proteins) necessary to living cells. These constituents would eventually arrange themselves into simple cell-like enclosures that Oparin called coacervates. Oparin then proposed a kind of Darwinian competition for survival among his coacervates. Those that developed increasingly complex molecules and metabolic processes would have survived and grown more complicated. Those that did not would have dissolved.
Thus, cells would have become gradually more and more complex as they competed for survival over billions of years. Like Darwin, Oparin employed time, chance and natural selection to account for the origin of complexity from initial simplicity. Moreover, nowhere in his scenario did "mind" or "intelligent design" or "a Creator" play any explanatory role. Indeed, for Oparin--a committed Marxist--such notions were explicitly precluded from scientific consideration. Matter interacting chemically with other matter, if given enough time and the right conditions, could produce life. Complex cells could be built from simple chemical precursors without any guiding personal or intelligent agency.
The Miller-Urey Experiment
The first experimental support for Oparin's hypothesis came in December of 1952. While doing graduate work under Harold Urey at the University of Chicago, Stanley Miller conducted the first experimental test of the Oparin chemical evolutionary model. Miller circulated a gaseous mixture of methane (CH4), ammonia (NH3), water vapor (H20) and hydrogen (H2) through a glass vessel containing an electrical discharge chamber. Miller sent a high voltage charge of electricity into the chamber via tungsten filaments in an attempt to simulate the effects of ultraviolet light on prebiotic atmospheric gases. After two days, Miller found a small (2 percent) yield of amino acids in the U-shaped water trap he used to collect reaction products at the bottom of the vessel. While Miller's initial experiment yielded only three of the twenty amino acids that occur naturally in proteins, subsequent experiments performed under similar conditions have produced all but one of the others. Other simulation experiments have produced fatty acids and the nucleotide bases found in DNA and RNA, but not the sugar molecules deoxyribose and ribose necessary to build DNA and RNA molecules.
Miller's success in producing biologically relevant "building blocks" under ostensibly prebiotic conditions was heralded as a great breakthrough. His experiment seemed to provide experimental support for Oparin's chemical evolutionary theory by showing that an important step in Oparin's scenario--the production of biological building blocks from simpler atmospheric gases--was possible on the early earth. Miller's work inspired many similar simulation experiments and an unprecedented optimism about the possibility of developing an adequate naturalistic explanation for the origin of life. Miller's experimental results also received widespread press coverage in popular publications such as Time magazine and gave Oparin's model the status of textbook orthodoxy almost overnight. As one writer put it:
"James Watson and Francis Crick unraveled the chemical basis of life . . . Stanley Miller discovered how matter and energy could create the building blocks of life without a preexisting cell. Unleashed from paralysis and spurred by the Space Age, research on the origin of life was launched by these . . .momentous achievements into an era of discovery and achievement."
Indeed, thanks largely to Miller's experimental work, chemical evolution is now routinely presented in both high school and college biology textbooks as the accepted scientific explanation for the origin of life. Yet as we shall see, chemical evolutionary theory is now known to be riddled with difficulties; and Miller's work is understood by the origin-of-life research community itself to have little, if any, relevance to explaining how amino acids--let alone proteins or livings cells--actually could have arisen on the early earth.
Problems with the Oparin/Miller Hypothesis
Despite its status as textbook orthodoxy, the Oparin chemical evolutionary theory has in recent years encountered severe, even fatal, criticisms on many fronts. First, geochemists have failed to find evidence of the nitrogen-rich "prebiotic soup" required by Oparin's model. Second, the remains of single-celled organisms in the very oldest rocks testify that, however life emerged, it did so relatively quickly--i.e. fossil evidence suggests that chemical evolution had little time to work before life emerged on the early earth. Third, new geological and geochemical evidence suggests that prebiotic atmospheric conditions were hostile, not friendly, to the production of amino acids and other essential building blocks of life. Fourth, the revolution in the field of molecular biology has revealed so great a complexity and specificity of design in even the "simplest" cells and cellular components as to defy materialistic explanation. Even scientists known for a staunch commitment to materialistic philosophy now concede that materialistic science in no way suffices to explain the origin of life. As Francis Crick has written: "An honest man, armed with all the knowledge available to us now, could only state that in some sense, the origin of life appears at the moment to be almost a miracle, so many are the conditions which would have had to have been satisfied to get it going."
To understand the crisis in chemical evolutionary theory, it will be necessary to explain in more detail the latter two difficulties, namely, the problem of hostile pre-biotic conditions and the problem posed by the complexity of the cell and its components.
When Stanley Miller conducted his experiment simulating the production of amino acids on the early earth, he presupposed that the earth's atmosphere was composed of a mixture of what chemists call reducing gases such as methane (CH4), ammonia (NH3) and hydrogen (H2). He also assumed that the earth's atmosphere contained virtually no free oxygen. Miller derived his assumptions about these conditions from Oparin's 1936 book. In the years following Miller's experiment, however, new geochemical evidence made it clear that the assumptions that Oparin and Miller had made about the early atmosphere could not be justified. Instead, evidence strongly suggested that neutral gases such as carbon dioxide, nitrogen and water vapor--not methane, ammonia and hydrogen--predominated in the early atmosphere. Moreover, a number of geochemical studies showed that significant amounts of free oxygen were also present even before the advent of plant life, probably as the result of volcanic outgassing and the photodissociation of water vapor.
This new information about the probable composition of the early atmosphere has forced a serious re-evaluation of the significance and relevance of Miller-type simulation experiments. As had been well know even before Miller's experiment, amino acids will form readily in an appropriate mixture of reducing gases. In a chemically neutral atmosphere, however, reactions among atmospheric gases will not take place readily and those reactions that do take place will produce extremely low yields of biological building blocks. Further, even a small amount of atmospheric oxygen will quench the production of biologically significant building blocks and cause any biomolecules otherwise present to degrade rapidly.
An analogy may help to illustrate. Making amino acids in a reducing atmosphere is like getting vinegar and baking soda to react. Because the reaction releases stored chemical energy as heat (i.e. it is "exothermic"), it occurs easily. Trying to make biological building blocks in a neutral atmosphere, however, is more like trying to get oil and water (or any two inert chemicals) to react.
Stanley Miller's experiment, and others like his, are only relevant to the origin of life if the reducing conditions he assumed actually existed on the early earth. Since independent geochemical evidence now strongly suggests that chemically hostile conditions prevailed, Miller's experiment cannot be said to "simulate" anything. Miller's work was heralded as a positive test of Oparin's chemical evolutionary scenario precisely because he had selected parameters for his experiment in accord with a then-current understanding of early atmospheric conditions. What made Miller's experiment significant was not the production of amino acids per se, but the production of amino acids from presumably plausible prebiotic conditions. As Miller himself stated, "In this apparatus an attempt was made to duplicate a primitive atmosphere of the earth, and not to obtain the optimum conditions for the formation of amino acids." Now, however, the situation has changed. The only reason to continue assuming the existence of a chemically reducing prebiotic atmosphere is that chemical evolutionary theory seems to require it. As Science magazine's Richard Kerr put it, "No geological or geochemical evidence collected in the last 30 years favors a strongly reducing primitive atmosphere. . .Only the success of the laboratory experiments recommends it."
While laboratory simulation experiments have failed to demonstrate the plausibility of chemical evolution, they may have inadvertently demonstrated the necessity of intelligent agency playing an active role in the design of living systems. Ironically, even successful simulation experiments require the intervention of the experimenters to prevent what are known as "interfering cross reactions" and other chemically destructive processes.
Assume for the moment that the reducing gases used by Stanley Miller do actually simulate the conditions on the early earth. Would his experimental results, then, support chemical evolution? Not necessarily. Miller-type simulation experiments have invariably produced non-biological substances in addition to biological building blocks such as amino acids and nucleic acid bases. Without human intervention, these other substances will react readily with biologically relevant building blocks to form a biologically irrelevant compound--a chemically insoluble sludge. To prevent this from happening and to move the simulation of chemical evolution along a biologically promising trajectory, experimenters have often removed those chemicals that degrade or transform amino acids into non-biologically relevant compounds. They must also artificially manipulate the initial conditions in their experiments. Rather than using both short and long-wavelength ultraviolet light which would be present in any realistic atmosphere, they use only short-wavelength UV. Why? The presence of the long-wavelength UV light quickly degrades amino acids. Thus, investigators have routinely manipulated chemical conditions both before and after performing "simulation" experiments in order to protect their experiments from destructive naturally occurring processes. These manipulations constitute what chemist Michael Polanyi called a "profoundly informative intervention."
They seem to simulate, if they simulate anything, the need for an intelligent agent to overcome the randomizing influences of natural chemical processes--processes that lead inexorably, under realistic conditions, to biochemical dead-ends.
The Molecular Biological Revolution and the Origin of Information
Yet a more fundamental problem remains for all chemical evolutionary scenarios. Even if it could be demonstrated that the building blocks of essential molecules could arise in realistic prebiotic conditions, the problem of assembling those building blocks into functioning proteins or DNA chains would remain. This problem of explaining the specific sequencing and thus, the information, within biopolymers, lies at the heart of the current crisis in materialistic evolutionary thinking.
In the early 1950s, the molecular biologist Fred Sanger determined the structure of the protein molecule insulin. Sanger's work made clear for the first time that each protein found in the cell comprises a long and definitely arranged sequence of amino acids. The amino acids in protein molecules are linked together to form a chain, rather like individual railroad cars comprising a long train. Moreover, the function of all such proteins (whether as enzymes or as structural components in the cell) depends upon the specific sequencing of the individual amino acids, just as the meaning of an English text depends upon the sequential arrangement of the letters. The various chemical interactions between amino acids in any given chain will determine the three-dimensional shape or topography that the amino acid chain adopts. This shape in turn determines what function, if any, the amino acid chain can perform within the cell. For a functioning protein, its three-dimensional shape gives it a "hand-in-glove" fit with other molecules in the cell, enabling it to catalyze specific chemical reactions or to build specific structures within the cell. The proteins histone 3 and 4, for example, fold into very well-defined three-dimensional shapes with a precise distribution of positive charges around their exteriors. This shape and charge distribution enables them to form part of the spool-like "nucleosomes" that allow DNA to coil efficiently around itself and to store information. Indeed, the information storage density of DNA, thanks in part to nucleosome spooling, is several trillion times that of our most advance computer chips.
To get a feel for the specificity of the three dimensional charge distribution on these histone proteins, imagine a large wooden spool with grooves on the surface. Next picture a helical cord made of two strands. Then visualize wrapping the cord around the spool so that it lies exactly into perfectly hollowed out grooves. Finally, imagine the grooves to be hollowed so that they exactly fit the shape of the coiled cord--thicker parts nestling into deeper grooves, thinner parts into more shallow ones. In other words, the irregularities in the shape of the cord exactly match irregularities in the hollow grooves. In the case of histone and DNA, there aren't actually grooves, but there is an uncanny distribution of positively charged regions on the surface of the histone proteins that exactly matches the negatively charged regions of the double stranded DNA that coils around it. Proteins that function as enzymes or that assist in the processing of information stored on DNA strands often have an even greater specificity of fit with the molecules to which they must bind. Almost all proteins function as a result of an extreme "hand-in-glove" three-dimensional specificity that derives from the precise sequencing of the amino acid building blocks.
The discovery of the complexity and specificity of protein molecules has raised serious difficulties for chemical evolutionary theory, even if an abundant supply of amino acids is granted for the sake of argument. Amino acids alone do not make proteins, any more than letters alone make words, sentences or poetry. In both cases, the sequencing of the constituent parts determines the function (or lack of function) of the whole. In the case of human languages the sequencing of letters and words is obviously performed by intelligent human agents. In the cell, the sequencing of amino acids is directed by the information--the set of biochemical instructions--encoded on the DNA molecule.
Information Transfer: From DNA to Protein
During the 1950s and 60s, at roughly the same time molecular biologists began to determine the structure and function of many proteins, scientists were able to explicate the structure and function of DNA, the molecule of heredity. After James Watson and Francis Crick elucidated the structure of DNA in 1953, molecular biologists soon discovered how DNA directs the process of protein synthesis within the cell. They discovered that the specificity of amino acids in proteins derives from a prior specificity within the DNA molecule--from information on the DNA molecule stored as millions of specifically arranged chemicals called nucleotides or bases along the spine of DNA's helical strands. (See Figure 2) Chemists represent the four nucleotides with the letters A, T, G, and C (for adenine, thymine, guanine and cytosine). As in the case of protein, the sequence specificity of the DNA molecule strongly resembles the sequence specificity of human codes or languages. Indeed, just as the letters in the alphabet of a written language may convey a particular message depending on their sequence, so too do the sequences of nucleotides or bases in the DNA molecule convey precise biochemical messages that direct protein synthesis within the cell. Whereas the function of the protein molecule derives from the specific arrangement of twenty different amino acids (a twenty-letter alphabet), the function of DNA depends upon the arrangement of just four bases. Thus, it takes a group of three nucleotides (or triplets as they are called) on the DNA molecule to specify the construction of one amino acid. This process proceeds as long chains of nucleotide triplets (the genetic message) are first copied during a process known as DNA replication and then transported (by the molecular messenger m-RNA) to a complex organelle called a ribosome. There at the ribosome site, the genetic message is translated with the aid of an ingenious adaptor molecule called transfer-RNA to produce a growing amino acid chain. (See Figure 3) Thus, the sequence specificity in DNA begets sequence specificity in proteins. Or put differently, the sequence specifity of proteins depends upon a prior specificity--upon information--encoded in DNA.
Naturalistic Approaches to the Problem of the Origin Of Information
The explication of this system by molecular biologists in the 1950s and 1960s, has raised the question of the ultimate origin of the specificity--the information--in both DNA and the proteins it generates. Many scientists now refer to the information problem as the "Holy Grail" of origin-of-life biology. As Bernd-Olaf Kuppers recently stated, "the problem of the origin of life is clearly basically equivalent to the problem of the origin of biological information." As mentioned previously, the information contained or expressed in natural languages and computer codes is the product of intelligent minds. Minds routinely create informative arrangements of matter. Yet since the mid-nineteenth century scientists have sought to explain all phenomena by reference to exclusively material causes. Since the 1950s, three broad types of naturalistic explanation have been proposed by scientists to explain the origin of information.
Biological Information: Beyond the Reach of Chance
After the revolutionary developments within molecular biology in the 1950s and early 1960s made clear that Oparin had underestimated the complexity of life, he revised his initial theory. He sought to account for the sequence specificity of the large protein, DNA and RNA molecules (known collectively as biomacromolecules or biopolymers). In each case, the broad outlines of his theory remained the same, but he invoked the notion of natural selection acting on random variations within the sequences of the biopolymers to account for the emergence of their specificity within these molecules. Others invoked the idea of a chance formation for these large information-bearing molecules by speaking of them as "frozen accidents." While many outside origin-of-life biology may still invoke "chance" as a causal explanation for the origin of biological information, few serious researchers still do.
Since molecular biologists began to appreciate the sequence specificity of proteins and nucleic acids in the 1950s and 1960s, many calculations have been made to determine the probability of formulating functional proteins and nucleic acids at random. Various methods of calculating probabilities have been offered by Morowitz, Hoyle, Cairns-Smith, Prigogine, Yockey and more recently, Robert Sauer. For the sake of argument, these calculations have generally assumed extremely favorable prebiotic conditions (whether realistic or not) and theoretically maximal reaction rates among the constituent monomers (i.e. the constituent parts of the proteins, DNA and RNA). Such calculations have invariably shown that the probability of obtaining functionally sequenced biomacromolecules at random is, in Prigogine's words, "vanishingly small . . .even on the scale of . . .billions of years." As Cairns-Smith wrote in 1971: "Blind chance...is very limited. Low-levels of cooperation he [blind chance] can produce exceedingly easily (the equivalent of letters and small words), but he becomes very quickly incompetent as the amount of organization increases. Very soon indeed long waiting periods and massive material resources become irrelevant."
Consider the probabilistic hurdles that must be overcome to construct even one short protein molecule of about one hundred amino acids in length. (A typical protein consists of about 300 amino acids, and some are very much longer). First, all amino acids must form a chemical bond known as a peptide bond so as to join with other amino acids in the protein chain. Yet in nature many other types of chemical bonds are possible between amino acids; in fact, peptide and non-peptide bonds occur with roughly equal probability. Thus, at any given site along a growing amino acid chain the probability of having a peptide bond is roughly 1/2. The probability of attaining four peptide bonds is: (1/2 x 1/2 x 1/2 x 1/2)=1/16 or (1/2)4. The probability of building a chain of 100 amino acids in which all linkages involve peptide linkages is (1/2)100 or roughly 1 chance in 10^30.
Second, in nature every amino acid has a distinct mirror image of itself, one left-handed version or L-form and one right-handed version or D-form. These mirror-image forms are called optical isomers. Functioning proteins tolerate only left-handed amino acids, yet the right-handed and left-handed isomers occurs in nature with roughly equal frequency. Taking this into consideration compounds the improbability of attaining a biologically functioning protein. The probability of attaining at random only L-amino acids in a hypothetical peptide chain 100 amino acids long is again (1/2)100 or roughly 1 chance in 10^30. The probability of building a 100 amino acid length chain at random in which all bonds are peptide bonds and all amino acids are L-form would be (1/4)100 or roughly 1 chance in 10^60(zero for all practical purposes given the time available on the early earth).
Functioning proteins have a third independent requirement, the most important of all; their amino acids must link up in a specific sequential arrangement just the letters in a meaningful sentence must. In some cases, even changing one amino acid at a given site can result in a loss of protein function. Moreover, because there are twenty biologically occurring amino acids the probability of getting a specific amino acid at a given site is small, i.e. 1/20. (Actually the probability is even lower because there are many non-proteineous amino acids in nature). On the assumption that all sites in a protein chain require one particular amino acid, the probability the probability of attaining a particular protein 100 amino acids long would be (1/20)100 or roughly 1 chance in 10^130. We know now, however, that some sites along the chain do tolerate several of the twenty proteineous amino acids, while others do not. The biochemist Robert Sauer of M.I.T has used a technique known as "cassette mutagenesis" to determine just how much variance among amino acids can be tolerated at any given site in several proteins. His results have shown that, even taking the possibility of variance into account, the probability of achieving a functional sequence of amino acids in several functioning proteins at random is still "vanishingly small," roughly 1 chance in 10^65 an astronomically large number. (There are 1065 atoms in our galaxy).
In light of these results, biochemist Michael Behe has compared the odds of attaining proper sequencing in a 100 amino acid length protein to the odds of a blindfolded man finding a single marked grain of sand hidden in the Sahara Desert, not once, but three times. Moreover, if one also factors in the probability of attaining proper bonding and optical isomers, the probability of constructing a rather short functional protein at random becomes so small as to be effectively zero. All these calculations thus simply reinforce the opinion that has prevailed since the mid-1960s within origin of life biology: chance is not an adequate explanation for the origin of biological specificity. What Mora said in 1963 still holds: “Statistical considerations, probability, complexity, etc., followed to their logical implications suggest that the origin and continuance of life is not controlled by such principles. An admission of this is the use of a period of practically infinite time to obtain the derived result. Using such logic, however, we can prove anything."
Pre-Biotic Natural Selection: A Contradiction in Terms
At nearly the same time that many researchers became disenchanted with "chance" explanations, theories of pre-biotic natural selection also fell out of favor. Such theories allegedly overcome the difficulties attendant pure chance theories by providing a mechanism by which complexity-increasing events in the cell would be preserved and selected. Yet these theories share many of the difficulties that afflict purely chance-based theories. Oparin's revised theory, for example, claimed that a kind of natural selection acted upon random polymers as they formed and changed within his coacervate protocells. As more complex molecules accumulated, they presumably survived and reproduced more prolifically. Nevertheless, to many, Oparin's discussion of differential reproduction seemed to presuppose a pre-existing mechanism of self-replication. Self-replication in all extant cells depends upon functional (and, therefore, to a high degree sequence-specific) proteins and nucleic acids. Yet the origin of these molecules is precisely what Oparin needed to explain.
Thus, many rejected the postulation of prebiotic natural selection as question begging. Functioning nucleic acids and proteins (or molecules approaching their complexity) seemed necessary to self-replication, which in turn seemed necessary to natural selection. Yet Oparin invoked natural selection to explain the origin of proteins and nucleic acids. As the evolutionary biologist Dobzhansky would proclaim, "prebiological natural selection is a contradiction in terms." Or as Pattee put it: ". . . there is no evidence that hereditary evolution occurs except in cells which already have the complete complement of hierarchical constraints, the DNA, the replicating and translating enzymes, and all the control systems and structures necessary to reproduce themselves." In any case, as just discussed, functional sequences of amino acids--i.e. proteins--cannot be counted on to arise via random events, even if some means of selecting them exists after they have been produced. Natural selection can only select what chance has first produced and chance, at least in a prebiotic setting, seems an implausible agent for producing the information present in even a single functioning protein or DNA molecule. Oparin attempted to circumvent this problem by claiming that the first polymers need not have been terribly specific.
But this claim raises doubts about whether self-replication (and thus, natural selection) could have proceeded at all. The mathematician Von Neumann, for example, showed that any system capable of self-replication would need to contain sub-systems that were functionally equivalent to the information storage, replicating and processing systems found in extant cells. His calculations and similar ones by Wigner, Landsberg, and Morowitz, showed that random fluctuations of molecules in all probability would not produce the minimal complexity needed for even a primitive replication system. Indeed, the improbability of developing a replication system vastly exceeds the improbability of developing the protein or DNA components of such system. As P.T. Mora put it:
To invoke statistical concepts, probability and complexity to account for the origin and the continuance of life is not felicitous or sufficient. As the complexity of a molecular aggregate increases, and indeed very complex arrangements and interrelationships of molecules are necessary for the simplest living unit, the probability of its existence under the disruptive and random influence of physico-chemical forces decreases; the probability that it will continue to function in a certain way, for example, to absorb and to repair, will be even lower; and the probability that it will reproduce, [is] still lower.”
For this reason most scientists now dismiss appeals to pre-biotic natural selection as essentially indistinguishable from appeals to chance.
Because of these difficulties, many origin-of-life theorists after the mid-1960s attempted to address the problem of the origin of biological information in a completely new way. Rather than invoking pre-biotic natural selection or "frozen accidents," many theorists suggested that the laws of nature and chemical attraction may themselves be responsible for the information in DNA and proteins. Some have suggested that simple chemicals might possess "self-ordering properties" capable of organizing the constituent parts of proteins, DNA and RNA into the specific arrangements they now possess. Steinman and Cole, for example, suggested that differential bonding affinities or forces of chemical attraction between certain amino acids might account for the origin of the sequence specificity of proteins. Just as electrostatic forces draw sodium ion (Na+) and chloride ions (Cl-) together into a highly-ordered patterns within a crystal of salt (NaCl), so too might amino acids with special affinities for each other arrange themselves to form proteins. This idea was developed in a book called Biochemical Predestination by Kenyon and Steinman in 1969. They argued that the origin of life might have been "biochemically predestined" by the properties of attraction that exist between constituent chemical parts, particularly between amino acids in proteins.
In 1977, another self-organizational theory was proposed by Prigogine and Nicolis based on a thermodynamic characterization of living organisms. In their book Self Organization in Nonequilibrium Systems, Prigogine and Nicolis classified living organisms as open, nonequilibrium systems capable of "dissipating" large quantities of energy and matter into the environment. They observed that open systems driven far from equilibrium often display self-ordering tendencies. For example, gravitational energy will produce highly ordered vortices in a draining bathtub; thermal energy flowing through a heat sink will generate distinctive convection currents or "spiral wave activity." Prigogine and Nicolis then argued that the organized structures observed in living systems might have similarly "self-originated" with the aid of an energy source. In essence, they conceded the improbability of simple building blocks arranging themselves into highly ordered structures under normal equilibrium conditions. But they suggested that, under non-equilibrium conditions, where an external source of energy is supplied, biochemical building blocks might arrange themselves into highly ordered patterns.
Order v. Information
For many current origin-of-life scientists self-organizational models now seem to offer the most promising approach to explaining the origin of biological information. Nevertheless, critics have called into question both the plausibility and the relevance of self-organizational models. Ironically, perhaps the most prominent early advocate of self-organization, Professor Dean Kenyon, has now explicitly repudiated such theories as both incompatible with empirical findings and theoretically incoherent. First, empirical studies have shown that some differential affinities do exist between various amino acids (i.e., particular amino acids do form linkages more readily with some amino acids than others). Nevertheless, these differences do not correlate to actual sequencing in large classes of known proteins. In short, differing chemical affinities do not explain the multiplicity of amino acid sequences that exist in naturally occurring proteins or the sequential ordering of any single protein.
In the case of DNA this point can be made more dramatically. Figure 4 shows the structure of DNA depends upon several chemical bonds. There are bonds, for example, between the sugar and the phosphate molecules that form the two twisting backbones of the DNA molecule. There are bonds fixing individual nucleotide bases to the sugar-phosphate backbones on each side of the molecule. There are also hydrogen bonds stretching horizontally across the molecule between nucleotide bases making so-called complementary pairs. These bonds, which hold two complementary copies of the DNA message text together, make replication of the genetic instructions possible. Most importantly, however, notice that there are no chemical bonds between the nucleotide bases that run along the spine of the helix. Yet it is precisely along this axis of the molecule that the genetic instructions in DNA are encoded. In other words, the chemical constituents that are responsible for the message text in DNA do not interact chemically in any significant way. Just as the letters in a Scrabble game can be combined and recombined in any way to form various sequences, so too can each of the four nucleotide bases attach to any site on the DNA backbone with equal facility, making all sequences equally probable (or improbable). Thus, "self-organizing" bonding affinities cannot explain the sequential ordering of the nucleotide bases along the spine of the DNA because there are no chemical bonds between the nucleotides that make the message text.
Because the same holds for RNA molecules, researchers who speculate that life began in an "RNA world," have also failed to solve the sequencing problem--i.e., the problem of explaining how information present in all functioning RNA molecules could have arisen in the first place. For those who want to explain the origin of life as the result of self-organizing properties intrinsic to the material constituents of living systems, these rather elementary facts of molecular biology have devastating implications. The most logical place to look for self-organizing properties to explain the origin of genetic information is in the constituent parts of the molecules carrying that information. But biochemistry and molecular biology make clear that forces of attraction between the constituents in DNA, RNA and proteins do not explain the sequence specificity of these large information-bearing biomolecules. Significantly, information theorists insist that there is a good reason for this. If chemical affinities between the constituents in the DNA message text determined the arrangement of the text, such affinities would dramatically diminish the capacity of DNA to carry information.
To illustrate, imagine receiving the following incomplete message over the wire. The "q-ick brown fox jumped over the lazy dog." Obviously someone who knew the conventions of English could determine which letter had been rubbed out in the transmission? Because "q" and "u" always go together by grammatical necessity, the presence of one indicates the probable presence of the other in the initial transmission of the message. The "u" in all English communications is an example of what information theorists call "redundancy." Given the grammatical rule "'"u' must always follow 'q'", the addition of the "u" adds no new information, when "q" is already present. It is "redundant" or unnecessary to determining the sense of the message (though not to making it grammatically correct).
Now consider what would happen if the individual nucleotide "letters" (A, T,G, C) in a DNA molecule did interact by chemical necessity with each other. Every time adenine (A) occurred in a growing genetic sequence, it would likely drag thymine (T) along with it. Every time cytosine (C) found a slot, guanine would follow. As a result, the DNA message text would be peppered with repeating sequences of A's followed by T's and C's followed by G's. Rather than having a genetic molecule capable of unlimited novelty with all the unpredictable and aperiodic sequences that characterize informative texts, we would have a highly repetitive text awash in redundant sequences--much as happens in crystals. Indeed, in a crystal the forces of mutual chemical attraction do completely explain the sequential ordering of the constituent parts and consequently crystals cannot convey novel information. Sequencing in crystals is highly ordered or repetitive, but not informative. Once one has seen "Na" followed by "Cl" in a crystal of salt, for example, one has seen the extent of the sequencing possible. In DNA, however, where any nucleotide can follow any other, innumerable novel sequences are possible, and a countless variety of amino acid sequences can be built.
The forces of chemical necessity, like grammatical necessity in our "q-and-u" example above, produce redundancy or monotonous order, but reduce the capacity to convey information and create novelty. As chemist Michael Polanyi has said: "Suppose that the actual structure of a DNA molecule were due to the fact that the bindings of its bases were much stronger than the bindings would be for any other distribution of bases, then such a DNA molecule would have no information content. Its code-like character would be effaced by an overwhelming redundancy. . . .Whatever may be the origin of a DNA configuration, it can function as a code only if its order is not due to the forces of potential energy. It must be as physically indeterminate as the sequence of words is on a printed page." (emphasis added) So, if chemists had found that bonding affinities between the nucleotides in DNA produced nucleotide sequencing, they would have also found that they had been mistaken about DNA's information-bearing properties.
To put the point quantitatively, to the extent that forces of attraction between constituents in a sequence determine the arrangement of the sequence, to that extent, will the information carrying capacity of the system be diminished. Bonding affinities, to the extent they exist, mitigate against the maximization of information. They cannot, therefore, be used to explain the origin of information. Affinities create mantras, not messages. The tendency to conflate the qualitative distinction between "order" and "information" has characterized self-organizational research efforts and calls into question the relevance of such work to the origin of life. As Yockey has argued, the accumulation of structural or chemical order does not explain the origin of biological complexity (i.e., genetic information). He concedes that energy flowing through a system may produce highly ordered patterns. Strong winds form swirling tornados and the "eyes" of hurricanes; Prigogine's thermal baths do develop interesting "convection currents"; and chemical elements do coalesce to form crystals. Self-organizational theorists explain well what doesn't need explaining. What needs explaining is not the origin of order (in the sense of symmetry or repetition), but the origin of information--the highly improbable, aperiodic, and yet specified sequences that make biological function possible.
To illustrate the distinction between order and information compare the sequence "ABABABABABABAB" to the sequence "Help! Our neighbor's house is on fire!" The first sequence is repetitive and ordered, but not complex or informative. The second sequence is not ordered, in the sense of being repetitious, but it is complex and also informative. The second sequence is complex because its characters do not follow a rigidly repeating or predictable pattern--i.e, it is aperiodic. It is also informative because, unlike a merely complex sequence such as "rfsxdcnct
Significantly, the nucleotide sequences in the coding regions of DNA have, by all accounts, a high information content--that is, they are both highly specified and complex, just like meaningful English sentences. Conflating order and information (or specified complexity) has led many to attribute properties to brute matter that it does not possess. While energy in a system can create patterns of symmetric order such as whirling vortices, there is no evidence that energy alone can encode functionally specified sequences--whether biochemical or otherwise. As Yockey warns: "Attempts to relate the idea of order . . . with biological organization or specificity must be regarded as a play on words which cannot stand careful scrutiny. Informational macromolecules can code genetic messages and therefore can carry information because the sequence of bases or residues is affected very little, if at all, by [self-organizing] physico-chemical factors."
The Return of the Intelligent Design Hypothesis
The preceding discussion suggests that the properties of the material constituents of DNA--like those of any information-bearing medium--are not responsible for the information conveyed by the molecule. Indeed, in all informational systems, the information content or message is neither deducible from the properties of the material medium nor attributable to them. The properties of matter do not explain the origin of the information.
To amplify this point consider, first, that many different materials can express the same message. The headline of this morning's New York Times was written with ink on paper. Nevertheless, many other materials could have been used to convey the same message. The information in the headline could have been written with chalk on a board, with neon-filled tubes in a series of signs, or by a sky-writer over New York harbor. Clearly, the peculiar chemical properties of ink are not necessary to convey the message. Neither are the physical properties (i.e., the geometric shapes) of the letters necessary to transmit the information. The same message could have been expressed in Hebrew or Greek using entirely different alphabetic characters. Conversely, the same material medium (and alphabetic characters) can express many different messages--i.e. the medium is not sufficient to determine the message. This November the Times will use ink and English characters to tell the reading public that either a Democrat, a Republican or a third-party candidate has won the Presidential election. Yet the properties of the ink and the 26 letters available to the type-setter will not determine which headline will be broadcast by the Times. Instead, the ink and English characters will permit the transmission of whatever headline the election requires, as well as a vast ensemble of other possible arrangements of text, some meaningful, and many more not. Neither the chemistry of the ink nor the shapes of the letters determine the meaning of the text. In short, the message transcends the properties of the medium.
The information in DNA also transcends the properties of its material medium. Because chemical bonds do not determine the arrangement of nucleotide bases, the nucleotides can assume a vast array of possible sequences and thereby express many different messages. (Conversely, various materials can express the same messages, as happens in variant versions of the genetic code or when laboratory chemists use English instructions to direct the synthesis of naturally occurring proteins). Thus, again, the properties of the constituents do not determine the function--the information transmitted--by the whole. As Michael Polanyi has said: "As the arrangement of a printed page is extraneous to the chemistry of the printed page, so is the base sequence in a DNA molecule extraneous to the chemical forces at work in the DNA molecule."
If the properties of matter (i.e., the medium) do not suffice to explain the origin of information, what does? Blind chance is, of course, a possibility but not, as we have seen in the case of DNA and proteins, where the amount of information (or the improbability of arrangement) gets too immense. The random selection and sequencing of Scrabble pieces out of a grab bag might occasionally produce a few meaningful words such as "cat" or "ran." Nevertheless, undirected selection will inevitably fail as the numbers of letters required to make a text increases. Fairly soon, chance becomes clearly inadequate as origin-of-life biologists have almost universally acknowledged.
Some have suggested that the discovery of some new scientific laws might explain the origin of biological information. But this suggestion betrays confusion on two counts. First, scientific laws don't generally explain or cause natural phenomena, they describe them. For example, Newton's law of gravitation described, but did not explain, the attraction between planetary bodies. Second, scientific laws describe (almost by definition) highly regular phenomena--i.e., order. Thus, to say that any scientific law can describe, or generate, an informational sequence, is essentially a contradiction in terms. The patterns that laws describe are necessarily highly ordered, not complex. Thus, like crystals, all law-like patterns have an extremely limited capacity to convey information. One might, perhaps, find a complex set of material conditions capable of generating high information content on a regular basis, but everything we know suggests that the complexity and information content of such conditions would have to equal or exceed that of any system produced, thus again begging the question about the ultimate origin of information. For example, the chemist J. C. Walton has argued (echoing earlier articles by Mora) that even the self-organization produced in Prigogine-style convection currents does not exceed the organization or information represented by the experimental apparatus used to create the currents. Similarly, Maynard-Smith and Dyson have shown that Manfred Eigen's so-called hypercycle model for generating information naturalistically is subject to the same law of information loss. They show, first, that Eigen's hypercycles presuppose a large initial contribution of information in the form of a long RNA molecule and some forty specific proteins. More significantly, they show that because hypercycles lack an error-free mechanism of self-replication, they become susceptible to various "error-catastrophes" that ultimately diminish, not increase, the information content of the system over time. Instead, our experience with information-intensive systems (especially codes and languages) indicates that such systems always come from an intelligent source--i.e., from mental or personal agents. This generalization holds not only for the information present in languages and codes but also for the non-grammatical information (also describable as specified complexity) inherent in machines or expressed in works of art. Like the text of a newspaper, the parts of a supercomputer and the faces on Mount Rushmore require many instructions to specify their shape or arrangement and consequently, have a high information content. Each of these systems are also, not coincidentally, the result of intelligent design, not chance or material forces.
Our generalization about the cause of information has, ironically, received confirmation from origin-of-life research itself. During the last forty years, every naturalistic model proposed has failed to explain the origin of information. Thus, mind or intelligence or what philosophers call "agent causation," now stands as the only known cause known to be capable of creating an information-rich system, including the coding regions of DNA, functional proteins and the cell as a whole. Because mind or intelligent design is a necessary cause of an informative system, one can detect (or, logically, retrodict) the past action of an intelligent cause from the presence of an information-intensive effect, even if the cause itself cannot be directly observed. Since information requires an intelligent source, the flowers spelling "Welcome to Victoria" in the gardens of Victoria harbor, lead visitors to infer the activity of intelligent agents even if they did not see the flowers planted and arranged. Similarly, the specifically arranged nucleotide sequences--the encoded information--in DNA imply the past action of an intelligent mind, even if such mental agency cannot be directly observed.
Moreover, the logical calculus underlying such inferences follows a valid and well-established method used in all historical and forensic sciences. In historical sciences, knowledge of the present causal powers of various entities and processes enables scientists to make inferences about possible causes in the past. When a thorough study of various possible causes turns up just a single adequate cause for a given effect, historical or forensic scientists can make fairly definitive inferences about the past. Several years ago, for example, one of the forensic pathologists from the original Warren Commission that investigated the assassination of President Kennedy spoke out to quash rumors about a second gunman firing from in front of the motorcade. Apparently, the bullet hole in the back of President Kennedy's skull evidenced a distinctive beveling pattern that clearly indicated its direction of entry. In this case, it revealed definitely that the bullet had entered from the rear. The pathologist called the beveling pattern a "distinctive diagnostic" to indicate a necessary causal relationship between the direction of entry and the presence of the beveling. Inferences based on knowledge of necessary causes ("distinctive diagnostics") are quite common in historical and forensic sciences, and often lead to the detection of intelligent, as well as, natural causes. Since Criminal X's fingers are the only known cause of Criminal X's fingerprints, X's prints on the murder weapon incriminate him with a high degree of certainty. In the same way, since intelligent design is the only known cause of information-rich systems, the presence of information--including the information-rich nucleotide sequences in DNA--implies an intelligent source. Scientists in many fields recognize the connection between intelligence and information and make inferences accordingly. Archaeologists assume a mind produced the inscriptions on the Rosetta Stone. Evolutionary anthropologists try to demonstrate the intelligence of early hominids by arguing that certain chipped flints are too improbably specified to have been produced by natural causes. N.A.S.A.'s search for extra-terrestrial intelligence (S.E.T.I.) presupposed that information imbedded in electromagnetic signals from space would indicate an intelligent source. As yet, however, radio-astronomers have not found information-bearing signals coming from space. But closer to home, molecular biologists have identified encoded information in the cell. Consequently, a growing number of scientists now suggest that the information in DNA justifies making what probability theorist William Dembski and biochemist Michael Behe call "the design inference."
During the last forty years, molecular biology has revealed a complexity and intricacy of design that exceeds anything that was imaginable during the late-nineteenth century. We now know that organisms display any number of distinctive features of intelligently engineered high-tech systems: information storage and transfer capability; functioning codes; sorting and delivery systems; regulatory and feed-back loops; signal transduction circuitry; and everywhere, complex, mutually-interdependent networks of parts. Indeed, the complexity of the biomacromolecules discussed in this essay does not begin to exhaust the full complexity of living systems. As even the staunch materialist Richard Dawkins has allowed, "Biology is the study of complicated things that give the appearance of having been designed for a purpose." Yet the materialistic science we have inherited from the late-nineteenth century, with its exclusive conceptual reliance on matter and energy, could neither envision nor can it now account for the biology of the information age. As Werner Gitt has said, throughout the natural sciences "energy and matter are considered to be basic, universal quantities. But the concept of information has become just as fundamental and far reaching. . . information has rightly become known as the third fundamental quantity." Or as Norbert Weiner put it, "Information is information, neither energy nor matter. No materialism that fails to take account of this can survive the present day." The molecular biology of the cell raises the possibility that "no materialism" will survive the revolution beginning to take root in science. While established journals and institutions continue to propagate the orthodoxies of a generation ago, many scientists, philosophers of science and mathematicians have begun to challenge these views and to formulate alternative approaches. Recent work in probability theory has defined information more precisely and articulated clear mathematical criteria for the identification of intelligently designed systems, thus providing a theoretical framework for a new science based upon the reality of design. A new book on the "irreducible complexity" of biochemical systems explains why gradual undirected evolution cannot produce such systems, and suggests intelligent design as the most viable scientific alternative. A new peer-reviewed journal, Origins & Design, opens this spring with a seminal article by a former chemical evolutionist turned design-advocate. Other work promises to reshape our conception, not only of living things but of our science and ourselves. If the simplest life owes its origin to an intelligent Creator, then perhaps man is not the "cosmic orphan" that twentieth century scientific materialism has taught. Perhaps then, during the twenty first century, the traditional moral and spiritual foundations of the West will find support from the very sciences that once seemed to undermine them.
For helpful comments and criticisms I would like to thank: Ed Olson, Priscilla DeWolf, Dean Kenyon, Jonathan Wells and Paul Nelson. For generous research support, I would like to thank The Pascal Centre, John and Georgia Wiester and C. Davis Weyerhaeuser.
Stephen C. Meyer is a Senior Fellow at the Discovery Institute in Seattle and an Associate Professor of Philosophy at Whitworth College in Spokane, Washington. He received an Ph.D. in the history and philosophy of science from the University of Cambridge in 1991 where he wrote his doctoral thesis about origin-of-life biology. He also holds degrees in physics and geology and has worked as a geophysicist for the Atlantic Richfield Company. In addition to technical articles in the philosophy of science, he has written for newspapers and magazines such as The Wall Street Journal, The Los Angeles Times, The Chicago Tribune, Insight and National Review. He is currently co-authoring one book (Signs of Mind: Detecting Design in Biological Systems) and editing another (Detecting Design in Creation) on the evidence for intelligent design in biology.
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