Origin Stories RNA, DNA, and a Dose of Imagination – Discovery Institute

Editors note: Eric Anderson is an attorney, software company executive, and co-author of the recently released book, Evolution and Intelligent Design in a Nutshell.

A new paper in Nature seeks to shed light on lifes origins from non-life on the early Earth, that is, on abiogenesis. Several outlets have picked up the story, including New Scientist. Phys.org explains that the research, led by Cambridge scientists, shows for the first time how some of the building blocks of both DNA and RNA could have spontaneously formed and co-existed in the primordial soup on Earth.

My purpose is not to question the research protocol or the results. No doubt the work is impeccable and the results as described. I am willing to assume that the researchers recreated early Earth conditions and demonstrated realistic prebiotic synthesis of deoxyadenosine, deoxyinosine, cytidine, and uridine. (Of course, early Earth conditions continue to be debated.)

This is fascinating, and it contributes to our understanding of these potential building blocks of RNA and DNA. What we do have to watch out for is how research results get interpreted within a naturalistic framework and sometimes get presented without the critical context.

The paper mentions the ongoing debate about whether abiogenesis began with RNA as the first carrier of information, giving rise to DNA (the RNA World hypothesis), or with RNA and DNA together at the same time. One of the challenges with the RNA World has been the lack of a plausible scenario to produce DNA from RNA under realistic prebiotic conditions. In addition, the genetic systems we are familiar with in biology today use both DNA and RNA, prompting some to suggest that a contemporaneous rise of DNA and RNA simplifies the abiogenesis scenario and, as the authors argue, streamlines the eventual genetic takeover of homogeneous DNA from RNA as the principal information-storage molecule.

On the other hand, one of the challenges facing this RNA/DNA World scenario is that it would have required the abiotic synthesis of building blocks of both DNA and RNA in close proximity and, preferably, under the same geochemical scenario. It is in this area that the researchers seek to make a contribution, demonstrating that certain building blocks of both RNA and DNA can be synthesized with prebiotically plausible reactions and substrates.

They conclude that RNA and DNA building blocks may have coexisted on the early Earth before the emergence of life. This is notable and seems, under the assumptions granted above, a reasonable conclusion.

However, the mere existence of RNA and DNA building blocks tells us little about the formation of life, with all its interrelated systems, including the information required to build and maintain and self-replicate that life.

The ultimate goal of abiogenesis researchers is to explain the emergence of life from non-life. John Sutherland, leader of the Cambridge group and one of the most accomplished origin-of-life researchers, observes, Our work suggests that in conditions consistent with shallow primordial ponds and rivulets there was a mixed genetic system with RNA and DNA building blocks co-existing at the dawn of life. This fulfills what many people think is a key precondition for the spontaneous emergence of life on Earth.

This is an impressive statement, and if we are not careful we might get the impression that in fact there was a mixed genetic system with RNA and DNA building blocks under early Earth conditions. We might get the further impression that because a key precondition had been fulfilled, we are moving steadily closer to explaining the spontaneous emergence of life on Earth. However, a closer look is warranted.

First, there was no mixed genetic system. In fact, there wasnt any kind of functional system, just molecules interacting under the normal tug-and-pull of physics and chemistry. Furthermore, a genetic system requires a special kind of functional capability. It requires not just DNA and RNA, but the information content that ebbs and flows between them. Meaning, a symbolic code, pursuant to which a string of nucleotides in the primordial DNA would be interpreted and translated into another state the symbolic and the immaterial being coaxed into the concrete and the material. Such a system necessarily involves information processing, with not just bare DNA storage at hand, but also retrieval and translation mechanisms. Such a system arising through unguided natural processes has never been observed, and we have theoretical and practical reasons to conclude it never will be.

Sutherland does not claim that their research demonstrates the existence of a primitive genetic system. He is more thoughtful in his wording, talking about how the authors work suggests a mixed genetic system. But that suggestion gains traction only in the context of an a priori story that has been assumed. Namely, that there must have been some kind of simple, naturally occurring system that eventually gave rise to the spontaneous emergence of life on Earth. Take away that assumption, and the suggestion of an early primitive genetic system, arising through unguided natural processes, evaporates.

The authors demonstrated the production of potential building blocks. Not all the building blocks needed for RNA and DNA as we know them, mind you, but some of the building blocks. They then suggest that this reduced number of building blocks could have served as a kind of alternative genetic alphabet. The headline from Cambridge teases us with this very possibility: Primitive genetic alphabet based on RNA and DNA.

Yet from an information-theoretic standpoint, having building blocks for a potential alphabet is unremarkable. I can build an information storage system out of sticks and stones.

There are multiple elephants in this room: What is the functional context of that system? Where does the information come from? How it is retrieved? How is it interpreted and acted upon? What is the overall meaning and purpose of that information? How does it become directed toward a comprehensive, integrated, cohesive end producing a living organism? The mere existence of molecules that could hypothetically serve as physical carriers of hypothetical symbols as part of a hypothetical primordial alphabet tells us nothing in response to these questions.

The researchers understand this, no doubt. The problem comes when we fail to appreciate that there is a fundamental difference in kind between having some building blocks on the one hand, and putting those building blocks to use in constructing a sophisticated functional system on the other. It is a critical distinction, and we might begin to suspect that no amount of research into the former can solve the latter. These are fundamentally different kinds of issues.

Are, then, research efforts toward forming the building blocks of RNA and DNA putting us on the path to a naturalistic abiogenesis explanation? Ill do you one better than building blocks. Lets stack the deck heavily in favor of the naturalistic story.

Ill give you all the nucleotides you want, formed and activated and ready to line up into nice polynucleotide chains. Ill even give them to you in just the right proportions for optimum effect. Ill give you the most hospitable environment for your fledgling structures to form. Ill throw in whatever type of energy source you want: just the right amount to facilitate the chemical reactions; not too much to destroy the nascent formations. Ill spot you that all these critical conditions occur in the same location and at the same time. Shoot, Ill even step in to prevent the inevitable interfering cross-reactions. Ill also miraculously make your fledgling chemical structures immune from both their natural rate of breakdown and from breakdown by other reagents in the environment.

Every one of the foregoing gifts represents an open question and a challenge to the abiogenesis account. Now, what do you think the next step is? What is your theory about how life forms?

There is no naturalistic answer. But taking time to at least think through the myriad problems with abiogenesis should be a required exercise for anyone proposing a naturalistic scenario.

Sutherland mentions that the groups research fulfills a key precondition for the spontaneous emergence of life on Earth. What was fulfilled? His point is that many people believe life had to start with both DNA and RNA together, not the traditional RNA World scenario that slowly gave rise to DNA.

He is right. There are good reasons for thinking life started with both DNA and RNA. Thats both because (as noted above) no one has been able to propose a plausible scenario that would produce DNA from RNA under real-world conditions, and also because the genetic systems we are familiar with in biology indeed include both DNA and RNA.

Yet the recent research did not demonstrate that such a genetic system can realistically arise by itself. Nor did it bring us closer to demonstrating the spontaneous emergence of life on Earth.

After all, beyond a genetic system, to keep life going on the early Earth another capability is required: self-replication. Many origin-of-life researchers view self-replication as the key goal, relying on the Darwinian process of mutation and natural selection to build the rest of the systems for the first organism. (See, for example, here and here.) Yet as I demonstrate in my engineering analysis in Evolution and Intelligent Design in a Nutshell, self-replication is not the starting point for the origin of life. Instead, it lies at the end of an extremely complicated, sophisticated, and specified engineering process. (p.84)

When we analyze what is required for the emergence of the simplest form of life No, when we step back further and analyze what is required for that oft-imagined precursor to life a single self-replicating molecule we find that the abiogenesis story has set forth on the wrong path from square one.

Make no mistake. This impressive work was performed by some of the most capable researchers in this field. The authors deserve recognition for it. Origin-of-life research doesnt get any better.

Yet for anyone tempted to think we are on our way to explaining the origin of life in naturalistic terms, what do we really have? Well, we now have building blocks on the early Earth that, potentially, could be used in some later process as part of the production of DNA and RNA. Alternatively, as the authors suggest, perhaps the building blocks could have served as the initial information carrier and then later turned into modern RNA and DNA.

Either way, these would then need to be carefully strung together into information-rich molecules, based on a symbolic code. That in turn would require multiple machines and interrelated systems to access, interpret, and utilize the information, which would further require a suite of hundreds of genes, components, and systems to survive in a prebiotic environment and self-replicate. None of these steps is plausible by purely natural means. All of them speak to the need for intelligent input.

Turning from the first life to a wonder of contemporary technology, consider a self-driving car. A marvel of engineering, a self-driving car has copious systems and sub-systems and components, made of numerous materials, organized in just the right way, and humming along under the control of sophisticated software dancing through carefully designed circuit boards and integrated circuit chips made from silicon. Yet, based on the engineering analysis I lay out in our book, we know that a self-replicating system requires much more than even all this.

Discovering how building blocks of RNA and DNA may have formed has about as much relevance to the spontaneous emergence of life on Earth as the discovery of naturally occurring silicon does to the spontaneous emergence of a self-driving car.

These building blocks have no interest in turning into an organism nor any tendency to do so. Instead, they will do what they always do, drifting in the primordial soup, suffering their normal rate of breakdown and unwilling to control their natural urges to cross-react with other interfering chemicals. All the while they are unaware of and indifferent to the fact that they might have, in the right hands, served as carriers for a simple genetic alphabet.

The modesty of the result of producing building blocks is due to the fact that this is all we can get from unguided natural processes. The result kind of, perhaps, with some imagination, might look like something that could be a precursor to life.

Forever lacking are the key elements required for life: coordinated activity, coherent function, regulated control, meaningful information, purposeful intent. These things require intelligence.

See original here:

Origin Stories RNA, DNA, and a Dose of Imagination - Discovery Institute