Abiogenesis & RNA World Part 2

Comment are off

By Jon Covey, BA, CLS(ASCP)

Edited by Anita Millen, MD, MPH, MA

The undirected, prebiotic synthesis of self-reproducing molecules on the hypothetical early Earth is so improbable that it is tantamount to promoting tooth fairies, pink elephants, and magic castles as real. Nevertheless, world class scientists debate the issue of whether life began via “RNA first” or “Metabolism first.”

Robert Shapiro, who died in 2011, discussed this and other problems associated with the RNA World. [1], [2], [3] Opposing him was the late Leslie Orgel,[4] whom the LA Times calls the father of the RNA World theory.[5] Few prebiotic researchers seem to question a purely chemical origin of life. Dean Kenyon, who wrote Biochemical Predestination, is one who did.

In his introduction to “Some Consequences of the RNA World Hypothesis,”[6] Orgel made an interesting remark:

“It now seems very likely that our familiar DNA/RNA/protein world was preceded by an RNA world in which ribosome-catalyzed, genetically-coded protein synthesis took no part. If this is indeed the case, it greatly simplifies the problem of the origin of life, since it suggests that everything that was required to transform the RNA world into the familiar DNA/RNA/protein world can be attributed to the operation of natural selection; RNA ‘learned’ to direct protein synthesis etc., etc. To understand the origin of life, therefore, one has only to understand the origin of the RNA world. I think that this is correct, but I do not believe that the implications of this point of view have been…widely appreciated.”

From this statement, it is easy to see why some evolutionists prefer the RNA World hypothesis. The mention of “natural selection” satisfies the expectation Darwinists have. Creationists have frequently shown that natural selection is not a viable mechanism for the origination of specified, functional biological information. Natural selection tends to conserve DNA sequences in genes. Nearly all mutations tend to diminish, and sometimes destroy, the function of the gene in which they occur.

We’ll put our review of the RNA world hypothesis on hold for a moment to re-examine some critical information we published in 2011 bearing on the issue of whether natural selection is really a viable mechanism for the origination of new functional biological information, since Orgel claims that natural selection was essential in producing an autonomous RNA organism.

Genetics is the most important evidence for or against the theory of evolution. Darwin’s claim was Natural Section is “the main, but not exclusive, means of modification.” In modern terms, natural selection acts upon mutations, either preserving or eradicating them from a species’ genome.

The Neutral Theory of Molecular Evolution

Motoo Kimura (1924-1994) was a Japanese mathematician and biologist who introduced the neutral theory of molecular evolution and became one of the foremost population geneticists. He is famous for showing that almost all mutations are nearly neutral – actually slightly deleterious or harmful.

Kimura discovered that mutations occurred so frequently and rapidly in a given population he was forced to conclude that most mutations were “effectively neutral,” because even at his supposed rate of one nucleotide substitution every two years, the genetic load would become so great that no mammalian species could survive over millions of years.

Effectively neutral mutations are like the tiny rust pits on your car’s undercarriage. They really wouldn’t affect the functioning of your car, but if the entire undercarriage of your car rusted out, it would become a big problem. You could no longer drive the car. Likewise, the long-term, cumulative effects of nearly neutral mutations will lead to big problems.

Population geneticists are concerned about this additive effect because these supposedly nearly neutral mutations spell extinction for our species. Individually, virtually harmless, additively these tiny variations become enormous and will kill all species.

The following graph depicts Kimura’s original figure that has been modified to include the tiny, but overly generous, red curve of a very rare beneficial mutation just to the right of zero. Gerrish and Lenski estimated this may happen once out of every million mutations (Genetica 102/103: 127-144, 1998). The curve to the left of zero on the x axis indicates the distribution of deleterious mutations. Mutations occur with great frequency, but they never reach the neutral zero point. They are never completely neutral as insisted, hence Kimura began describing them as “effectively neutral.” Lethal mutations would be to the extreme left of zero.

As you can see, most mutations are within the “no selection zone,” including the rare beneficial one. This means that natural selection cannot eliminate the slightly deleterious mutations or retain the rare slightly beneficial one, much less the greatly beneficial one. Clearly, any mutation falling outside the zone can be acted upon by natural selection, although in most cases they aren’t. Otherwise, natural selection would have eliminated mutations, such as the potentially lethal Factor V Leiden mutation known to cause deep vein thrombosis, from the human genome. For instance, some genes predispose a person to certain cancers, while other cancers are the result of new mutations during a person’s life.

There are thousands of mutations known to degrade the genome. Most are minor in their effect, but some cause severe medical problems. I was impressed with the 850 mutations James Jandl listed in Blood: Textbook of Hematology for just the beta hemoglobin molecule. That is astounding—850 different mutations that affect the production of beta hemoglobin enough to cause a patient’s physician to order expensive tests. This does not include silent mutations, which produce only very slightly degrading effects formerly undetectable.

How would Kimura have reacted to the much higher mutation rates discovered since scientists have decoded the entire human genome?, The 1000 Genomes Project discovered about 8 million mutations in the genomes of just 800 people. In November 2010, Science reported that the project discovered about 75 variants known to be associated with disease in each individual.

How could natural selection, or even a brilliant genetic engineer, backtrack to clean up the degraded genome with its millions of nearly neutral mutations? Individually, they escape the culling of natural selection because they have almost no perceptible effect on the organism, but together, they could potentially cause extinction the whole species.

With our current genetic knowledge, how should geneticists view Darwin’s ideas? His ideas about genetics are wrong, and so are those of the neo-Darwinian synthesis. On what foundation should evolutionary theory rest? Considering how rapidly mutations occur, current DNA knowledge presents a formidable challenge to the theory of evolution.

In Feb 2017 Evolution News “Putting the RNA World Theory to the Test with ‘Pistol,’”[7] looks at the current thinking on the RNA World hypothesis:

“So far, we learn that only a “handful” of ribozymes are known, they have some jobs to do in living cells, and the RNA World hypothesis ‘speculates.’ We would really like to see some testable science, not speculation.

“Specifically, the RNA World hypothesis needs to satisfy four requirements:

  1. A ribozyme must form spontaneously in plausible prebiotic conditions. No intelligent design allowed.
  2. It must be able to replicate itself before the first cell appears, so that natural selection can kick in.
  3. It must do something useful for a future living organism.
  4. It must store the information on how to do that useful something. (Note: cutting yourself in half is a poor candidate for a useful function.)”

Prebiotic RNA Synthesis Could Not Happen in Water

The National Center for Biotechnology Information (NCBI) website examines the abiotic synthesis of RNA in water. Even the most ardent critics of abiogenesis, mainly panspermia advocates (Crick, Hoyle), believe that life arose from nonlife by entirely natural processes and utterly reject that God or some intelligent agent had anything to do with the origin of life on Earth.

Shapiro, as a leading chemist, takes the RNA World hypothesis to task and offers his own solution to the problems confronting the hypothesis. Some evolutionists believe the RNA World is true, claiming montmorillonite clay served as a template, bonding with RNA nucleotides and protecting them from the kind of destruction Shapiro described. At the same time, they accept Shapiro’s solution that “energy-driven networks of small molecules afford better odds as the initiators of life,”[8] firmly planting their feet in two diverging boats. However, leading origin-of-life investigators, following Leslie Orgel’s lead, champion some form of the RNA World hypothesis. In his 2004 paper,[9] he attempted to show that critical molecules necessary for the advent of RNA molecules capable of enzymatic activity (ribozymes) and carriers of information similar to DNA could arise in Darwin’s warm little pond. One such molecule is ribose, a critical component of RNA and DNA nucleotides. We’ll examine this in more detail in our next issue.

[1] Shapiro R “A simpler origin of life,” Sci Am 296:47–53(2007).

[2] Shapiro, R “Prebiotic cytosine synthesis: A critical analysis and implications for the origin of life,” ProcNatlAcadSci 1999 Apr 13.

[3] Shapiro, R “The improbability of prebiotic nucleic acid synthesis,” Orig Life, 1984;14(1-4):565-70

[4] Orgel, L “Prebiotic Chemistry and the Origin of the RNA World,” Crit Rev Biochem Mol Bio 39:99-123

[5] LA Times, “Leslie Orgel,80; chemist was father of…”

[6] Orgel, L, Origins of Life and Evolution of the Biosphere 33: 211–218, 2003.

[7] https://www.evolutionnews.org/2017/02/putting_the_rna/

[8] Ibid, Shapiro “A simpler…”

[9] Orgel, L., “Prebiotic chemistry and the origin of the RNA World,” Critical Reviews in Biochemistry and Molecular Biology, 39:99-123, 2004

About the Author

Jon Covey and is wife Anita have been long-time members of the South Bay Creation Science Association. Jon and Anita write the monthly Creation in the Crossfire newsletter and have been invaluable in adding great research and insight into the creation articles we send out.