A Question of Life
Now, with a universe coming into existence that just happens to be fit for stars, planets, and complex chemistry, we have the question of how those biochemically complex systems (that we call life) came about. Even if an environment is perfectly suitable for habitation, it does not mean that it will automatically and necessarily produce the inhabitants. The arrival of such inhabitants is a separate marvel to be explained.
The problem of abiogenesis (the origin of the first lifeform) is one of the thorniest and most intractable issues in chemistry. Our increasing knowledge of microbiology and earth history has only added to the complexity of what needs to be explained. The simplest life is equivalent to modern bacteria, which is loaded with complex activity, information, and molecular "machines." The fossil record does not give evidence that there was a "prebiotic soup," or that there were any biological precursors to the first organisms, or that the atmosphere was the ideal mix to yield the necessary molecules, or that there was the expected long period of time between when the Earth could support life and when it actually appeared. Evolutionists regularly segregate the abiogenesis problem from the issue of evolution because (1) it is a challenge they'd rather not be saddled with, or (2) it is the most logical point for possible divine intervention. However, for the atheist there is no escaping this issue; they are obliged to seek out some purely natural explanation.
What hope for an explanation do you have? Are you satisfied to have problems like this that are unanswered, or even unanswerable?
In telling the tale of life on earth science writers often unconsciously use the word "miracle" for the appearance of the first organisms.
What kind of evidence is needed before we are to actually accept that something like this really is a miracle?
Randall starts us off by rejecting the idea that this is even a significant scientific challenge.
I don't know that [abiogenesis] is a thorny issue. Scientists see this as a fascinating issue; it's no thorn in anyone's side.
I think that any scientific issue that has been the victim of 150 years of unrequited investigation has the right to be called something like "thorny"; and if this issue does not qualify for such a label, then all of science must consist of simple and "fascinating" problems.
Faithlessgod thinks that I have overestimated the problem and that solutions are just around the corner.
Now is it the thorniest and most intractable problem, I don't think so. The fact that Pruett asks this is indicative that he really does not comprehend the nature of the work in this field. . . . it is not like we have no idea of the origins of life, indeed it is the opposite, we already have too many theories! . . . Of course we do not know which one is correct and all the current ones have some shortcomings . . . It most certainly is not at all intractable.
I do indeed comprehend the nature of the work in this field. It's not a naïve idea that everyone is just sitting around shrugging their shoulders that makes me call this an "intractable" problem; it's the knowledge of the issues relating to such work that leads me to use the term. The very fact that we have "too many theories" is a case in point. We only have competing theories because there is not a promising candidate bereft of difficulties. Faithlessgod admits that "all the current ones have some shortcomings," but a more accurate word than "shortcomings" would be "showstoppers."
I'll take the time here to review some of the technical roadblocks generally encountered by origin of life researchers. Later we’ll look at more specifics.
- Life requires water, but the very presence of water prevents many of the chemical reactions required to build molecules necessary for life.
- Certain conditions sufficient to form necessary molecules are just as likely to destroy them once created, like heat or UV rays.
- The conditions sufficient to yield certain molecules are hostile to other necessary molecules. But those independent components of life must be able to coexist and survive before they can hope to form into units.
- No matter how interesting a thing might be produced by chance, it is meaningless if it cannot reliably reproduce itself.
- Even if a self-replicating molecule could manage to form by chance it is a quantum leap between that and the next theoretical level, which is something that can produce other molecules (like proteins) for its own functional entourage and also reproduce itself.
- The simplest life that we know of or can even conceive of as a functional package is epitomized by interdependent systems that must come about as a group, with none of the parts serving any isolated function. There is a huge void between independent molecules (of any complexity) and life.
- Any meager gains in theorizing how some part of a cell might come to form are continually outdistanced by the increase in knowledge of what it is that is to be explained.
- Even where some mechanism might be theorized to form essential molecules, the statistical problem of fortuitous assembly of those molecules still remains, e.g., how you build a functional polypeptide chain (protein) from loose amino acids.
- The time for chance to do its work is shrinking. By many estimates, life's appearance is now in the 3.8 to 3.5 billion year range, and this may only be because we have difficulty detecting it prior to these dates (note: Earth is alleged to be 4.5 billion years old, and would not have been suitable for life for hundreds of millions of years after that time).
Randall waxes nostalgic about some work from the 50's, which offered the first real experimental encouragement for origin of life researchers. She responds, "There are hundreds of theories of life's origins. The fact is, since the 50's, we've been improving on the Urey-Miller experiment." She then goes on to give a summary of the Urey-Miller experiment (extended by Carl Sagan), which produced some of the building blocks of life. She concludes by saying, "So we know it can happen."
First, I should point out that it is a long way between making a few building blocks of life to saying that you know that abiogenesis can happen! One might just as well claim that observing that stone can erode in block shapes means we know that the natural formation of Egyptian pyramids can happen by chance alone.
Second, let's go ahead and take a look at this experiment to get an idea of the specific kinds of problems associated with abiogenesis.
- This experiment is dependent upon the assumption that early Earth's atmosphere was "reducing," and could thus form biologically significant molecules. That assumption is debatable (reference, reference, reference).
- It was also important that the experimental environment be free of oxygen, which would be fatal to the formation of the desired molecules. Unfortunately, the date for the existence of free oxygen is being pushed back earlier and earlier in Earth's history, back to the time in which life was thought to have first appeared (reference, reference, reference).
- The primary, significant molecular output of this experiment was amino acids, which are the building blocks of proteins. But only about half of the simpler amino acids used by life were produced.
- All life is comprised of left-hand amino acids, but this experiment (and every other process known) produces both left and right-hand versions without discrimination. Peptide bonding has no preference for linking one form over the other, though advanced functionality depends upon them all being one handedness (known as homochirality).
- Remember that this is a controlled experiment — intelligently designed, if you will. It contains a mechanism (a trap) to preserve the synthesized molecules from being destroyed once again by the two energy points and the water within the system. For this reason, the yield is certainly higher and more persistent than anything that might be found in nature.
- Of the molecules that were produced and captured, the vast majority were biologically meaningless. The largest percentage was a tarry polymer, which would be evidenced in the geological record if amino acids in desirable quantities were produced by similar means on the early earth.
- Given the limitations of the last few points, the overall yield of such an actual process in nature would have produced a very dilute prebiotic "soup." The thinner the broth, the less would be the chances for the right mix of molecules to find each other in order to combine. And remember, the combination of these molecules into meaningful systems is a matter of astronomical chance, which depend upon mass quantities to overcome statistical improbability. This is why oceans full of prebiotic molecules have long been the great hope and assumption of researchers in this field.
Francois doesn't deny that abiogenesis is a tough issue, only that it counts against materialism.
The fact that an issue is intractable does not indicate anything about that issue. It is only a statement about ourselves. We may not have enough evidence to get to the solution. There may even be limits on what human intelligence can comprehend, and a problem may remain intractable forever.
It's not what we don't know about chemistry that leads to the conclusion that this is a problem; it's what we do know. In fact, it was our past ignorance that led some to conclude that it wasn't a problem at all. Darwin's idea of life arising out of some warm little pond sounded plausible when it was thought that the cell was nothing more than a simple blob of protoplasm. And if you were to challenge scientists at that time for a solution they would be far more justified in saying, "Give us some time. We've only just begun to study the protoplasm to know what we're up against."
Today we understand much of the cell all the way down to the molecular makeup. In fact, we understand it and the problem so well that scientists no longer can fathom that the first organism would have been a complete cell; there supposedly must have been a series of proto-cellular entities leading up to even the simplest of the cells that we observe. (Francois affirms this modern adjustment to the theory when he says, "No abiogenesis hypothesis actually states that the simplest life is as complex as modern bacteria, and if it did, it wouldn’t be a very good hypothesis at all.") Never mind that the progression is totally speculative, it includes huge leaps, there is no evidence of such things, and that the existence of complete cells has been pushed so far back in history that the time for chance to build the cell by degree is vanishingly small.
For the committed materialist, this should be an answerable question in principle; chemistry is a fairly straightforward and empirical science. We should at least be able to show the chemical pathways to life even if we have difficulty in connecting those steps to actual geological history. If life indeed formed by natural means, then this has every hope of being experimentally repeatable. Unfortunately, decades of research have offered only a few token victories. I wonder how long we are to wait before applying any skepticism toward the materialist's story. 150 more years? 500 years?
Francois appears to think that we should wait forever; that it is unwarranted to ever plug God into any of our equations:
[This] is merely a modern iteration of the "god of the gaps" argument: "we can't figure out how abiogenesis actually happened, there is no hope to ever explain it, therefore God did it."
It is not as though science is annually filling gaps that Christians have tried to reserve for God. In fact, I'm struggling to think of any such gaps in recent history where God has been banished by science. On the contrary, modern science has revealed many "gaps" for which divine intervention is a neat and consistent fit. This issue of the origin of life and the need of a transcendent cause is a perennial one, which predates Christianity itself. The insistence that the cause is, nay, must be, a materialistic one is a historical newcomer (or at least was the minority report).
Darwin came along and offered us an alternate story. Why must we accept that story by default unless there is compelling reason to do so? Why should we accept "science" of the gaps in all matters? Richard Dawkins has famously said that "biology is the study of complicated things that give the appearance of having been designed for a purpose." If this is so, then it seems reasonable to assume that biology really is designed for a purpose unless and until it is demonstrated not to be. Materialism not only denies the burden of proof but any need at all to prove its own case. Crying "god of the gaps" is a stall tactic that has begun to ring hollow. In its echo I hear only, "we don't know." And “we don’t know” surely does not qualify as proof.
Here is another interesting problem for those who demand a material, unguided cause for life. There have been some who have honestly proposed that life might have come by way of directed panspermia. But how could we ever know if life were seeded by extraterrestrials if we are forced to rule out causal agents? Certainly, that would be a "natural" cause for life (since aliens are part of nature), but detecting the signs (or need) of such an intervention will be ruled out just the same by the prevailing methodology of naturalism.
One thing on which all my critics were united is the belief that I have mistaken what the fossil record is capable of revealing about early life.
The assertion that "the fossil record" does not contain evidence of the origins of life [is extremely problematic]. How in the hell could there be? Fossils form from hard structures like bones or the imprint of organisms in soft soil.
And why exactly would one think the FOSSIL record would say anything about atmospheric conditions or non-organic matter? Only organic matter is fossilized, which means there would be NO fossils until after complex life was formed.
And Faithlessgod says:
Really, how on earth does the fossil record tell us anything about the prebiotic soup? In saying this Pruett displays a deep ignorance of this topic.
To avoid this confusion, perhaps I should have used "geological" in place of "fossil" record. However, it is not at all uncommon to see the word "fossil" actually used in relation to phenomena surrounding life rather than just the remains of life itself. Terms like "molecular fossil," "geochemical fossil," and "fossil biomarkers" can often be found in the scientific literature. Some specific examples of early formations that are considered fossils, but are not themselves the direct remains of life are stromatolites and oncolites.
Beyond the quibble over my use of the word "fossil," the larger issue is whether or not we can detect much evidence for the state of the early earth and the earliest life forms by looking at the geological strata. Judging by the numerous studies and scientific papers, the answer to that question seems to be "yes." Some of the biochemical signatures of life or early life conditions would include banded iron formations, carbon isotope data, and other chemical biomarkers.
Additionally, it is not just bones and hard body structures of life that may be found in the fossil record, but even simple cellular life. Such "microfossils" have helped us to date the appearance of life (in forms that still exists today) to a time shortly after our planet was stable, but have not yet given evidence for the existence of any precursors to life. For instance, if an ocean rich in amino and nucleic acids had existed, which are necessary precursors of life, this would have left large deposits of nitrogen-rich minerals (nitrogenous cokes). Such finds are conspicuously absent from the early geological record.
Anath offers up a popular solution, and one that I, frankly, find to be the least absurd:
My current favorite theory is the RNA world theory but I understand that it is not without its difficulties. The reason I like it primarily has to do with the fact that I can visualize how it might occur and it seems like a logical explanation of how complex life could arise through simple enzymes and inorganic material. However, I also freely admit that my knowledge of biochemistry is pretty weak
That is part of the problem with this whole issue: it is easy to devise and believe just-so stories about how life came into existence. It is when these stories are examined in detail that we find the deep technical problems. Some may easily visualize how we could ultimately travel to the stars by going faster and faster with advanced spacecraft, or using worm holes, but any amateur astronomer or physicist can burst that bubble with a little dose of reality.
Here's a quick rundown of some of the issues with the RNA-first theory:
- The same kinds of problems as with amino acids apply here, e.g., being able to create all necessary components, low yields, assumptions about earth conditions, homochirality issues (left/right-handedness).
- RNA is chemically fragile (especially so at higher temperatures) and difficult to synthesize abiotically.
- The fortuitous assembly of a catalyzing RNA chain is improbable enough, much more so one which could copy itself.
- The known range of RNA's catalytic activities is rather narrow. Self-replicating capabilities are unknown, though a "cross-catalytic system involving two RNA enzymes" has been engineered. But that only compounds the probability issue, since chance would now have to provide two complementary RNA ribozymes at the same time and place.
- Even assuming nature could produce the various necessary molecules in the same locale and in sufficient quantities for chance to do its work, it is no guarantee that other chemicals would not be present to interfere with the assembly of RNA chains.
- If an RNA world actually thrived for the millions of years it would surely take to yield the DNA world, then it is odd that nothing of it remains. We certainly have every other flavor of lower organism still on display in modern times, e.g., when the eukaryotes came on the scene, the prokaryotes did not perish.
- It is still a monstrous, inexplicable leap from RNA to the interdependent DNA-RNA-protein system (among other functions) of cellular life.
In a 2006 article in Commentary magazine, David Berlinski wrote a thorough essay outlining the problems and critiquing the proposed solutions. Organic chemist, Robert Shapiro (himself a supporter of evolutionary theory), says of Berlinski's essay, "the case against an 'RNA world' is even stronger than the one Mr. Berlinski presents. Not only were cytosine and ribose unlikely to have been present in any quantity on the early earth, but the same can also be said of adenine and guanine. Moreover, no adequate explanation of the manner in which these parts (and others) could connect together spontaneously to form RNA has ever been presented."
Long is not to be discouraged by such pesky details. He hangs his hope on a general confidence in the power of nature:
Scientists are constantly discovering new forms of spontaneous order, and I fully expect that trend to continue.
I recently read a sneering article which imagined that it refuted intelligent design by pointing out the "spontaneous order" that can naturally arise in the world of free market economics. I am not at all clear on how a system of conscious agents working in willful synergy serves as a good analog for mindless chemical reactions. On the other hand, there are indeed things in nature that naturally form into orderly chemical arrangements, like crystals, carbon fullerenes, and nanotubes. The problem is that order alone is not enough. Neither is complexity. Life is made up of molecules that contain specified complexity — they are in a specific, meaningful order.
A large crystal is very orderly; however, it is nothing but repeating patterns that form up according to natural, chemical laws — a reliable and reproducible process. On the other hand, the proteins, RNA, and DNA molecules in life are not comprised of repeating patterns. They are also not comprised of patterns that arise due to any natural affinities that one molecule might have for another. They are comprised of unique, specific arrangements of molecules that confer functionality to the system. In the case of DNA it is like hardware and software. Perhaps some natural process could be found that would make DNA strands — the hardware — but the arrangement of the nucleotides upon that strand is the software that drives life, and there are no chemical or electrical laws that cause nucleotides to naturally form into information-laden arrangements.
The arrangement of DNA is often compared to language, so let me end with this analogy. Even if we could find some way of spilling alphabet cereal that caused the letters to form into strings and columns (all right-side up), it still would not mean that they would make meaningful words and sentences. There is a quantum leap difference between discovering order in nature and discovering information.
Several of the responders objected to my use of the word "miracle" to characterize the reaction of scientists to this problem.
Self has this to say:
I cannot help that some writers use the word "miracle" to describe something. Some scientists may, indeed, believe that a miracle did occur; but others do not and may have just used sloppy language to state their case.
DB0 goes further to accuse me of outright dishonesty:
When a Scientist says "Miracle," he may actually mean something with a probability so low, that it's amazing that it even happened. Of course if one considers the sheer size of the universe, the possibility of anything like that not happening is what starts to get low.
However to take a word in general, claim that science writers use it, while not providing a context, and then use that as some kind of subconscious belief is nothing more than equivocation and very intellectually dishonest.
I mention the word "miracle" because it is a testimony to the fact that the scientific community does indeed recognize the scope of the problem and the shortcomings of the proposed theories. This word is seldom employed by science commentators; there is a reason it is used in this case.
Due to the intentional brevity of my original article I was necessarily constrained from offering quotes and detailed context for my questions. It is unfortunate that this should be received as "intellectual dishonesty." My context is that the word "miracle" has been used too many times to count in scientific exhibits and documentaries to which I have been exposed, as well as its direct use by the scientific community. Since my reply is anything but brief, I'll now reference just a few such cases where the word is used by academics in relation to life.
One of the miracles of life, to my mind, is the accuracy with which DNA gets itself replicated in the cell. It has to be that unbelievably accurate, otherwise we'd all die out in no time. (Alexander Graham Cairns-Smith)
As far as we've looked, there's only one place in the entire universe where the miracle of life exists: our own planet Earth. (Carl Sagan)
An honest man, armed with all the knowledge available to us now, could only state that in some sense, the origin 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. (Francis Crick)
The de novo appearance of oligonucleotides [i.e., specifically sequenced RNA bases] on the primitive Earth would have been a near miracle. (Orgel and Joyce)
Even I am willing to forgive these materialists for their "sloppy language," but the fact that there exist such vacuums into which the word "miracle" can readily slip tells us something about the nature of the problem. I can't remember the last time I've heard a mathematician, geologist, or chemical engineer employ the word. It seems that those who study life and its origins must be a particularly "sloppy" group, or there is something else going on here.
Is the appearance of life a "miracle" simply because it is a hard problem to solve, or because it is a matter of vanishingly small probability that it should have appeared? I would argue, and I think I have argued, that it is both. Nobel Laureate Christian de Duve has called for "a rejection of improbabilities so incommensurably high that they can only be called miracles, phenomena that fall outside the scope of scientific inquiry." The chance appearance of functional DNA, RNA, proteins and other elaborate large molecules qualify as such.
Some of my responders think it doesn't really make a difference if this is a problem for materialism that may never be solved. Francois offers this challenge:
If we accept the statement that the origins of life is a "miracle," the question remains unchanged: how did it happen? Even if Christianity was true, the Creationist would be no closer to an answer.
Self adds the following:
I'm very comfortable saying that any given problem can be unanswered. I'm not sure why xians feel that everything they can possibly imagine must be answered and if our current capability doesn't permit an answer then we must posit some sort of god intervention.
The point is not that all questions must be answered. There are some questions that by their very nature may not be answerable because there is a categorical disconnect between the cause and effect, like what caused the Big Bang. This is especially true when involving causal agents. For instance, we may never know the motive for the JFK shooting (why it was done), but we certainly can know how he was killed.
In principle, we should be able to say whether or not abiogenesis is possible. If such processes are part of the flow of the present material, observable world, then there is every reason to think that we could discover them. There is no practical veil between the cause and effect except our current ignorance.
If one is suggesting a natural mechanism or law, then one has something particular which could be exhaustively tested. But how do we know that something happened by natural means unless we can demonstrate that nature is capable of producing such a thing? The devil is entirely in the details in this case. Philosophical materialism seems to get a pass on this, unlike other theories that must offer evidences before warranting conclusions.
On the other hand, if life is the product of divine intervention, then there is a break of continuity with nature that we cannot push past with our theories and experiments. We cannot say precisely how God did it unless He tells us Himself, i.e., did He create from scratch, did He shepherd molecules together with secondary causes, etc. It is more a historical question than an experimental one. The best we can do, in principle, is to observe the evidence that life appeared without precursor and despite insurmountable improbability. We could find the various fingerprints on nature, at particular historical points, but not know the precise means of the handling.
It is not necessary to know the exact means by which an action is taken in order for it to be reasonable to believe that it did happen. If I find a fort standing where I left a pile of wood the night before, then I may not know how it was assembled or who did it, but I will surely be justified in my skepticism toward theories of natural causes.
Christianity is happy to live with open questions since it believes that God has reserved some mysteries to Himself. But some questions are relevant to the debate over His very existence. Materialists assure us that there is no evidence or need of a creator in the biological realm due to alleged natural processes for which they will someday find concrete support. Is it so unusual that theists should require evidence of such a thing before accepting its validity?
Regarding my observation that the issues of evolution and abiogenesis are so commonly segregated, Faithlessgod says this:
Some evolutionary biologists do separate origins from the evolution of life but simply because their specialty is the evolution of life, abiogenesis is not what they study. . . . Pruett seeks to manufacture a problem or an issue which does not really exist here.
Anath adds the following:
"Evolutionists" segregate abiogenesis because abiogenesis is a separate field of study. The Theory of Evolution deals only with the events AFTER abiogenesis, and cannot explain the origin.
Admittedly, it is two parts of a larger puzzle. In fact, it must be, because evolution only acts upon what is already alive and capable of reproducing. This makes it all the more difficult for origin of life researchers, since the gulf to be bridged is between simple chemistry and a complex self-replicating assembly rather than just "simple" mutations on existing DNA molecules. As Lynn Margulis has said, "To go from a bacterium to people is less of a step than to go from a mixture of amino acids to a bacterium."
However, I find it curious that the separation is so often and quickly pointed out in debates I have seen and had myself. It seems less for the sake of technical precision than for the sake of insulating evolution from collateral damage. At a metaphysical level, one may compartmentalize these two issues for distinct explanations. For instance, one could be driven purely by nature and the other require some transcendent involvement. However, the atheist does not have this luxury; He is saddled with a purely natural explanation for both. If one cannot be explained, then the entire atheistic project is failed.
To my question of what kind of evidence is needed to prove that the appearance of life is, in fact, miraculous, Anath replies:
A crocoduck. Something COMPLETELY impossible and unexplainable. Life rising from non-life is NOT a crocoduck. It is unusual and potentially quite improbable, but it is not unexplainable.
How can one dogmatically assert that abiogenesis is not unexplainable when it has for so long defied explanation and suffers all the practical roadblocks that I have presented here and more? This is merely the expression of a dogmatic faith in materialism.
Life from non-life cannot be like a crocoduck, in principle. As affirmed by you previously, evolution, which a crocoduck would supposedly confound, is a physically distinct issue from abiogenesis. Even if a crocoduck were discovered it would, at most, refute the theory of evolution. That is, unless you want to embrace the idea that they are indeed bound as one issue.
It seems to me that there is nothing analogous to this for abiogenesis that could be discovered, or that is not already known. The indisputable data we have is that it is simple chemistry on the one side and complete cellular life on the other. Discoveries of “crocoducks” in between the two might only serve to give confidence in the power of material causes, not refute it.
As it happens, neither the ongoing problems with each theory of essential molecule formation nor the increased understanding of the complexity of what is to be explained have served in any way to dampen the spirits of the committed materialists (with notable exceptions). What more could be discovered to disprove the materialists creation story? It is the incorrigible nature of the lack of supporting evidence for it that has any hope to stand as proof against it. But if “we’re looking into it” may eternally serve as justification for materialism, then any statistical improbability may be put into play.
As to the fate of evolution upon finding a "crocoduck," I am confident that belief in it would soldier on. The model would merely see a descriptive adjustment or make yet another place on its shelf for a future explanation. I have seen it happen many times before. The foundations may shudder and crack, but no one ever seems to question whether they have built their temple upon the wrong frame.
Some examples of “crocoducks”:
- Biological classifications based on various markers (e.g., morphology and specific gene sequences) often do not align as expected. (reference, reference)
- The meager accumulated evidence (since Darwin’s time) for the predicted gradualism as witnessed by 1) events like the Cambrian explosion, and 2) the discovery that the fossil record is most often characterized by patterns of stasis and punctuation.
- The discovery that the fundamental cellular domains of bacteria, archaea, and eukaryotes are found not to fit into the classical tree of life model (i.e., there is no clear line of descent either before them or between them). (reference, reference)
- The discovery that the cell not only contains unfathomably complex molecules, but information-laden molecules.
- The discovery that cells consist predominately of molecular machines, many of which are analogous to macro-scale human-designed machines. (reference, reference)
- Even the genetic approximate of a "crocoduck" does nothing to phase the theory.
After effectively deflating the various theories of abiogenesis in his book, Origins: A Skeptic’s Guide to the Creation of Life in the Universe, Robert Shapiro makes the following interesting statement.
Some future day may yet arrive when all reasonable chemical experiments run to discover a probable origin of life have failed unequivocally. Further, new geological evidence may yet indicate a sudden appearance of life on the earth. Finally, we may have explored the universe and found no trace of life, or processes leading to life, elsewhere. Some scientists might choose to turn to religion for an answer. Others, however, myself included, would attempt to sort out the surviving less probable scientific explanations in the hope of selecting one that was still more likely than the remainder.
The materialist is free to continue seeking his alternative explanations, but it is unfair to demand that all explanations must always be "natural" even if they elude us for eternity. This is tantamount to saying that atheism wins, game over, and no further issues or anomalies will ever be considered as strikes against it. This seems a presumptive stance in a historically god-soaked world that, to use Dawkins' language, is full of "complicated things that give the appearance of having been designed for a purpose." Perhaps it appears that way because it actually turns out to be true. It is certainly consistent with the story that theism has been telling all along. Scientists may determine among themselves that all explanations must be by way of mindless, natural causes, but I am less interested in following the doctrines of "science," as defined by its secular high priests, than I am in discovering truth.