It’s been a month, but I haven’t forgotten!  For new readers, this is part 6 in my series of posts summarizing Stephen Meyer’s argument for design from his new book, Signature in the Cell.  Past posts can be found here: Parts 1, 2, 3, 4, and 5.

In the last two installments we demonstrated that the OOL cannot be explained by either chance or necessity.  Now we’ll turn our attention to the possibility that the OOL can be explained by a combination of both chance and necessity.  While many models could be examined—and were examined by Meyer—I will only examine the RNA-first, a.k.a. the RNA World hypothesis, since this is the prevailing OOL model today.

The cell presents OOL researchers with a chicken-and-the-egg paradox of which came first: the DNA that makes proteins, or the proteins necessary for replicating DNA?  The paradox was insoluble, so another solution was required.  If neither DNA nor proteins could arise first, what did?

Carl Woese, Francis Crick, and Leslie Orgel proposed an RNA-first model in the late 1960s, followed by Walter Gilbert (Harvard biophysicists) who developed it in the 1980s and gave it its common name.[1]  This model proposes that the first cell consisted of a much simpler self-replicating, self-catalyzing RNA (RNA is similar to DNA, but it is a single strand rather than a double helix, and the nucleotide, thymine, is replaced by uracil).[2]  This model was largely fueled by the discovery of Thomas Cech and Sidney Altman in the early 1980s that sometimes RNA can catalyze chemical reactions like an enzyme does, and thus RNA could serve the dual purpose of information storage (like DNA) and enzymatic functions (like proteins).  “The paradox of the chicken and the egg was thus resolved by the hypothesis that the chicken was the egg.”[3]

Chance is said to have produced the first self-replicating RNA molecule by associating nucleotides, sugars, and phosphates in the pre-biotic soup.  Eventually RNA adapter molecules were produced to bind amino acids together to produce proteins, and eventually through a process of reverse transcription, the information in RNA is transferred to DNA when DNA comes on the scene.[4]

Meyer identifies five problems with this model, but I am including others that I am aware of as well:

1.       Obtaining the raw materials

Three components make up an RNA molecule: a sugar, nucleotides, and a phosphate group.  For an RNA-based life to have arisen by naturalistic means, nature must be capable of producing all three components under the same pre-biotic conditions and in the necessary quantities.  Is there reason to believe this is possible?

Nucleotides

RNA nucleotide bases are difficult to synthesize, and easy to destroy.  No nucleotides have been synthesized in spark-discharge experiments like the ones conducted by Stanley Miller in the 1950s, and none are found on meteorites.  While intelligent agents have been able to artificially synthesize adenine, guanine, and uracil in the lab, the same is not true of cytosine.  As David Berlinski writes:

Not a trace of the stuff [cytosine] has been found in any meteor.  Nothing in comets, either, so far as anyone can tell.  It is not buried in the Antarctic.  Nor can it be produced by any of the common experiments in pre-biotic chemistry.  Beyond the living cell, it has not been found at all.
When, therefore, M.P. Robertson and Stanley Miller announced in Nature in 1995 that they had specified a plausible route for the pre-biotic synthesis of cytosine from cyanoacetaldehyde and urea, the feeling of gratification was very considerable.  But it has also been short-lived.  In a lengthy and influential review published in the 1999 Proceedings of the National Academy of Science, the New York University chemist Robert Shapiro observed that the reaction on which Robertson and Miller had pinned their hopes, although active enough, ultimately went nowhere.  All too quickly, the cytosine that they had synthesized transformed itself into the RNA base uracil (U) by a chemical reaction known as deamination, which is nothing more mysterious than the process of getting rid of one molecule by sending it somewhere else.[5]

Additionally, nucleotides (and amino acids) cannot form in the presence of oxygen, and yet we now know oxygen was present on the early earth.  Furthermore, while adenine and guanine will form in the presence of phosphorous, cytosine and uracil will not.

Even if we could imagine conditions under which all four nucleotides could have been produced naturally in the necessary quantities and geography on the early earth, the extreme temperature conditions would have caused the nucleotides to quickly break down.  At 100 degrees Celsius, adenine and guanine have half-lives of one year, uracil has a half-life of 12 years, and cytosine just 19 days.  Even in cooler temperatures cytosine only has a half-life of 340 years, which means quantities would disintegrate over time, not accumulate.  OOL theorist Robert Shapiro said the notion that “the bases, adenine, cytosine, guanine and uracil were readily available on the early earth” is “not supported by existing knowledge of the basic chemistry of these substances.”[6]

One further problem is the fact that ribose and nucleotides come in left-handed and right-handed varieties.  Life uses only the right-handed varieties, so the presence of right-handed varieties would produce interfering cross-reactions either preventing the formation of an RNA molecule, or prohibiting replication.

Ribose

Ribose is very difficult to synthesize.  It will not form in the presence of nitrogenous substances, such as nucleotides and amino acids.[7]  So if nature solved the problem of producing all four nucleotides, it would prevent the production of ribose necessary to make RNA molecules.  Ironically, then, the RNA-first model creates a chicken-and-the-egg scenario of its own.  It’s like trying to bake an ice-cream cake in one step: The conditions needed to make the cake prohibit making the ice cream and vice-versa.  To make an ice cream cake, each component needs to be made under two separate sets of conditions, and then brought together at some later stage.  That is why Robert Shapiro concluded, “The evidence that is currently available does not support the availability of ribose on the prebiotic earth, except perhaps for brief periods of time, in low concentration as part of a complex mixture, and under conditions unsuitable for nucleotide synthesis.”[8]

Furthermore, ribose is synthesized by enzymes.  What synthesizes enzymes?  RNA!  Again, a chicken-and-the-egg paradox emerges.  RNA is needed to synthesize the enzymes that make the ribose necessary to form RNA in the first place.  While there are other ways to make small amounts of ribose (not enough for life), they yield other products that interfere with life.  As John Horgan wrote for Scientific American:

But as researchers continue to examine the RNA-world concept closely, more problems emerge. How did RNA arise initially? RNA and its components are difficult to synthesize in a laboratory under the best of conditions, much less under plausible prebiotic ones. For example, the process by which one creates the sugar ribose, a key ingredient of RNA, also yields a host of other sugars that would inhibit RNA synthesis.[9]

Phosphorus

The final component of an RNA molecule, phosphorus, is relatively rare in nature.  How, then, did the abundant supply of phosphorous that is necessary for RNA formation form?

 2.       Assembling the raw materials into an RNA molecule

Even if nature was able to produce the right quantities of phosphate, ribose, and nucleotides, and each component existed in the same geographical location, it does not guarantee the formation of an RNA molecule anymore than the mere presence of all the raw materials needed to build a house guarantees the formation of a house.  Since each component is stable on its own, scientists have had a hard time getting the three to bond into an RNA molecule.  It takes the aid of an intelligent agent who can divvy up the sugars and bases, introduce them into the process at different points in time and in specific sequences, and then purify the products at each step in the process.  As OOL researcher, Robert Shapiro wrote:

Walter Gilbert proposed that life began with an “RNA World.” Life started when an RNA molecule that could copy itself was formed, by chance, in a pool of its own building blocks. Unfortunately, a half century of chemical experiments have demonstrated that nature has no inclination to prepare RNA, or even the building blocks (nucleotides) that must be linked together to form RNA. Nucleotides are not formed in Miller-type spark discharges, nor are they found in meteorites. Skilled chemists have prepared nucleotides in well-equipped laboratories, and linked them to form RNA, but neither chemists nor laboratories were present when life began on the early Earth.[10]

3.       Ribozymes are poor substitutes for proteins

Ribozymes can only perform a small number of the thousands of functions performed by modern proteins.  Thinking a cell can function using only ribozymes is like thinking a carpenter can build a house using only a hammer.[11]

4.       Doesn’t explain the origin of genetic information

As discussed in a previous post, the primary problem to be explained is the origin of biological information.  Interestingly, the RNA-first model doesn’t even attempt to explain it.  The model was only intended to explain the interdependence between nucleotides and proteins for the cell’s information processing center.  So it assumes information from the start. 

The first RNA molecule would have to be sequence-specific in order to self-replicate and perform catalytic functions.  A natural, fully self-replicating RNA molecule would require at least 200 properly sequenced nucleotide bases (that’s 10120 different sequence possibilities).  Furthermore, a second RNA molecule virtually identical to the first would be required as a template for self-replication.  The odds of getting two such strands are 1:10240.  The number of strands necessary to get the two required for self-replication exceeds the number of elementary particles in the universe by a factor of 10160!  Even if these incredible odds were met, we would have to weigh the odds of both RNA strands forming at the exact same time, and in the same geographical location.[12]  This would require one miracle on top of another.

5.       RNA does not self-replicate / Requires the presence of intelligence

Experimental data shows that RNA molecules do not self-replicate.  While Tracey Lincoln and Gerald Joyce have recently been able to get 10% of an RNA molecule to supposedly “self-replicate”[13] in the lab, the RNA molecule itself was pre-engineered for the task (and hand-picked out of a pool of 1,000,000,000,000 engineered RNA molecules, almost all of which were incapable of any self-replication whatsoever), required the researchers to provide a complementary copy to act as a template for replication, and required that the researchers remove all competing chemical by-products at each step in the process to avoid interfering cross-reactions in the next step.[14]  This minimal success is entirely the result of intelligent engineering.  As David Berlinski noted of the research, “They began with what they needed and purified what they got until they got what they wanted.”[15]  If scientists hope to demonstrate the possibility of life arising from non-life by purely naturalistic processes rather than by the aid of an intelligent designer, not only do they need to demonstrate a plausible chemical pathway in conditions that actually correspond to those of the early earth, but they also need to demonstrate that this pathway does not require the intervention of intelligent agents! 

Even if a true, fully self-replicating RNA molecule could be synthesized in the lab, it would merely demonstrate the truth of Intelligent Design, not Darwinism.  The eminent Darwinist, Robert Shapiro, has made this same observation:

It is probably only a matter of time, to be measured in years rather than decades, before a self-sustained RNA evolving system can be demonstrated in the laboratory.  This would be a case in which a DNA-and protein-based life form, namely a human biochemist, gives rise to an RNA-based life form, an interesting reversal of the sequence of events that occurred during the early history of life on Earth.  When that event takes place, the media will probably announce it as the demonstration of a crucial step in the origin of life.  I would agree, with one modification.  The concept that the scientists are illustrating is one of intelligent design.  No better term can be applied to a quest in which chemists are attempting to prepare a living system in the laboratory, using all the ingenuity and technical resources at their disposal.  Whether they use synthetic chemicals or materials isolated from nature, we would be justified in calling the living system artificial or human-made life. [16]

It’s no surprise that if you provide all the right components in all the right quantities and in the right location, and if you remove competing reactions, and if you engineer RNA to help it do what you want it to do, that it does so.  These experiments may be interesting achievements in chemistry, but they tell us nothing about the OOL.  As Michael Behe wrote, “You don’t learn much about the fair odds of winning at poker by watching a cardsharp deal himself a royal flush, and you don’t learn much about random mutation by arranging genes in the lab on purpose.”[17]  When an intelligent agent is involved in the process, what is naturally impossible becomes possible.  Take away that intelligent agent, however, and you are still left with the impossible.  For OOL experiments to demonstrate anything about how life originated on earth through naturalistic means, they must put forth a chemically plausible scenario that does not require the intervention of an intelligent agent every step of the way. 

6.       Implausible transition from RNA to DNA

No plausible explanation is provided for how the cell developed a coding and translation system based on RNA, or where the information came to build the proteins that would be needed later on to replace RNA.[18]  Furthermore, no plausible explanation is provided for how a primitive RNA molecule might have evolved into the modern cell complete with DNA and proteins.  Eugene Koonin writes: “Despite considerable experimental and theoretical effort, no compelling scenarios currently exist for the origin of replication and translation, the key processes that together comprise the core of biological systems and the apparent prerequisite of biological evolution.  The RNA World concept might offer the best chance for the resolution of this conundrum, but so far cannot account for the emergence of an efficient RNA replicase or the translation system.”[19]  John Maynard Smith similarly writes:

The origin of the [genetic] code is perhaps the most perplexing problem in evolutionary biology. The existing translational machinery is at the same time so complex, so universal, and so essential that it is hard to see how it could have come into existences or how life could have existed without it. The discovery of ribozymes has made it easier to imagine an answer to the second of these questions, but the transformation of an “RNA world” into one in which catalysis is performed by proteins, and nucleic acids specialize in the transmission of information, remains a formidable problem.[20]

Conclusion

The RNA World has anything but solved the problem of the OOL.  The abundance of challenges facing the RNA World model is why Leslie Orgel, atheist OOL researcher and proponent of the model himself wrote, “It would be a miracle if a strand of RNA ever appeared on the primitive Earth.”  Indeed, Robert Shapiro considers the evidence against the RNA World to be so powerful that he attributes its continued acceptance in the scientific community to closed-minded dogmatism, going so far as to call it mythology:

We shall see that the adherents of the best known theory [soup theory, RNA world] have not responded to increasing adverse evidence by questioning the validity of their beliefs, in the best scientific tradition; rather, they have chosen to hold it as a truth beyond question, thereby enshrining it as mythology.  In response, many alternative explanations have introduced even greater elements of mythology, until finally, science has been abandoned entirely in substance, though retained in name.[21] 

If the OOL and biological information cannot be explained by appeals to chance or necessity, what can explain it?  An intelligent agent.  Our routine experience confirms over and over again that intelligent agents, and only intelligent agents, are capable of creating complex, specified structures that bear functional information.  As Meyer wrote:

[I]ntelligent agents have demonstrated the capacity to produce large amounts of functionally specified information (especially in a digital form).  Second, no undirected chemical process has demonstrated this power.  Hence, intelligent design provides the best – most causally adequate – explanation for the origin of the information necessary to produce the first life from simpler non-living chemicals.  In other words, intelligent design is the only explanation that cites a cause known to have the capacity to produce the key effect in question.[22]

Given our extensive knowledge of what needs to be explained, our knowledge of the limits of naturalistic processes to account for it, and the capabilities of intelligent agents, the most reasonable conclusion is that a designing intelligence is responsible for the origin of life.  To reject this conclusion on the grounds that it is “unscientific” reveals more about one’s philosophical commitments than it does the empirical evidence itself.  The empirical evidence is clear, and it points to the involvement of a designing intelligence.  


[1]Stephen C. Meyer, Signature in the Cell: DNA and the Evidence for Intelligent Design (New York: Harper One, 2009), 281-91.
[2]Such strands of RNA are called “ribozymes.”
[3]David Berlinski, “On the Origins of Life”; available from http://www.discovery.org/a/3209; Internet; accessed 10 June 2006.
[4]Stephen C. Meyer, Signature in the Cell: DNA and the Evidence for Intelligent Design (New York: Harper One, 2009), 298-300.
[5]David Berlinski, “On the Origins of Life”; available from http://www.discovery.org/a/3209; Internet; accessed 10 June 2006.
[6]Robert Shapiro, “Prebiotic Cytosine Synthesis,” 4396, as quoted in Signature in the Cell, 302.
[7]The work of John Sutherland (published May 2009) may be cited as an exception, but his experiment lacks pre-biotic plausibility.  As Meyer explains in “Response to Darrel Falk’s Review of Signature in the Cell” (http://www.signatureinthecell.com/responses/response-to-darrel-falk.php), Sutherland was only able to synthesize two ribonucleotides (uracil and cytosine), and he did so by excluding left-handed ribose sugars that appear in nature but would have interfered with the desired chemical reactions, he had to intervene at several steps in the process to purify the reactions, and he intelligently and strategically introduced different chemicals at different times in the process to get the result he wanted.  In doing so Sutherland demonstrated the indispensable role intelligent agents must play in the process.  It does not represent what is possible in nature.
[8]Robert Shapiro, “Prebiotic Ribose Synthesis,” 91, as quoted in Signature in the Cell, 303.
[9]John Horgan, “In The Beginning…,”, Scientific American, February 1991, p.103.
[10]Robert Shapiro, “We Shall Understand the Origin of Life Within the Next 5 Year”; available from http://www.edge.org/q2006/q06_9.html#shapiro; Internet; accessed 6 January 2006.
[11]Stephen C. Meyer, Signature in the Cell: DNA and the Evidence for Intelligent Design (New York: Harper One, 2009), 304.
[12]Stephen C. Meyer, Signature in the Cell: DNA and the Evidence for Intelligent Design (New York: Harper One, 2009), 312-6.
[13]Meyer says that to even say their research resulted in RNA “self-replication” is a “gimmick,” because all they succeeded in doing was getting two pre-synthesized RNA chains to form a single phosphate bond to produce a longer chain.  They did not succeed in getting an RNA molecule to copy itself using free-standing nucleotides in its environment.  It is the researchers who did the replicating, not the RNA.  See Stephen Meyer, “Response to Darrel Falk’s Review of Signature in the Cell”; available from http://www.signatureinthecell.com/responses/response-to-darrel-falk.php; Internet; accessed 29 January 2010.
[14]Casey Luskin, “Origin of Life Researchers: Intelligent Design of Self-Replicating RNA Molecules Refutes Intelligent Design”; available from http://www.evolutionnews.org/2009/02/origin_of_life_researchers_int.html; Internet; accessed 02 February 2010.
[15]David Berlinski, “The RNA World”, letter to the editor of The Times Literary Supplement; available from http://www.evolutionnews.org/2010/01/responding_to_stephen_flethers.html; Internet; accessed 18 January 2010.
[16]Robert Shapiro, Planetary Dreams: The Quest to Discover Life Beyond Earth (John Wiley & Sons: New York, 1999), pp.102-4.
[17]Michael Behe, The Edge of Evolution: The Search for the Limits of Darwinism (New York, NY: Free Press, 2007), 273.
[18]Stephen C. Meyer, Signature in the Cell: DNA and the Evidence for Intelligent Design (New York: Harper One, 2009), 305-12.
[19]Eugene Koonin, “The Cosmological Model of Eternal Inflation and the Transition from Chance to Biological Evolution in the History of Life”, in Biology Direct, May 2007.
[20]John Maynard Smith and Eors Szathmary, The Major Transitions in Evolution (W.H. Freeman and Co.: Oxford, 1995), 81.
[21]Robert Shapiro, Origins: A Skeptics Guide to the Creation of Life on Earth (Random House, 1986), 32.
[22]Stephen Meyer, “Response to Darrel Falk’s Review of Signature in the Cell”; available from http://www.signatureinthecell.com/responses/response-to-darrel-falk.php; Internet; accessed 29 January 2010.