A new research paper in Science demonstrates yet more evidence for abiogenesis -- finally a 3D map of the chemical structure of a beautiful example of a ribozyme, one which researchers built "from scratch" and could very easily have evolved naturally under the right chemical conditions. See the EurekAlert!, and a perspective on the research:
As the gaps in our knowledge continue to close, the "god of the gaps" continues to shrink along with them. This is as true today of the "Intelligent Design" creationism movement as it was of Young Earth Creationists and their pseudo-scientific arguments against evolutionary biology.No known RNA enzyme in biology catalyzes the polymerase-like joining of RNA. However, the powerful methods of in vitro evolution have made it possible to generate such enzymes from scratch, starting from a large population of RNAs with random sequences (6). The usual approach is first to evolve an RNA enzyme that is an RNA ligase, which can join two oligonucleotides in a template-directed manner. Then, through further evolution, the researcher attempts to coax the ligase to accept NTPs as substrates and to add multiple NTPs in succession.
Bartel and colleagues (7) have used one such in vitro evolved ligase, the class I ligase, and evolved it further to polymerize as many as 14 successive NTPs with high fidelity. Despite valiant efforts, however, it appears unlikely that this particular polymerase enzyme will ever be evolved to the point that it can copy RNA molecules as long as itself (~200 nucleotides). Nonetheless, it is likely that scientists will eventually apply a similar approach to a different set of RNA molecules to achieve more extensive polymerization and ultimately complete replication.
A very recent case-in-point is shown by Dr. Michael Egnor's rejection of evolution on the basis of a half-baked conception of evolution's inability to generate biological "information," which I refuted with peer-reviewed resources here. After reading Orac shredding the fallacies propounded by Dr. Michael Egnor, and especially the, "Duh, I don't know or understand this, so it must not be true!" (classic argumentum ad ignorantium), I wanted to highlight his section on the origin of the genetic code:
I'll agree that how the genetic code evolved is indeed a very good scientific question, but it is a question that in no way poses a threat to current evolutionary theory or requires the postulation of some sort of intelligence to explain. Indeed, it's a hot topic of research for evolutionary biologists, with computer simulations evaluating the plausibility of various explanations and competing hypotheses being tested scientifically. If you search PubMed, you'll find over 5,000 articles about or touching on the evolution of the genetic code, and PubMed doesn't even index many evolutionary biology journals in which such articles would be expected to appear. Indeed, there was a rather interesting paper in PNAS in November about how the universal genetic code may have emerged as determined by studying of transfer RNAs. It also seems to me that Egnor also sounds almost Lamarckian in the way he describes how animals evolve thicker coats in response to cold climate. He also seems not to have considered that the very fact that the genetic code is very nearly universal for all organisms can also be viewed as supporting evolution. If the development of the genetic code appeared very early in the history of life, that would go a long way towards explaining why nearly all life, from bacteria to humans, uses the same code, and even the variants of the genetic code that exist are minor.Indeed. In addition to these papers, I wanted to highlight six other recent reviews that give a great overview of the present scientific thinking towards the origin of the genetic code:
- "Selection, history and chemistry: the three faces of the genetic code.", Trends in Biochemical Sciences, Volume 24, Issue 6, 1 June 1999, Pages 241-247 (full-text .pdf)
- "Genetic code: Lucky chance or fundamental law of nature?", Physics of Life Reviews, Volume 1, Issue 3, Dec 2004, Pages 202-229 (full-text .pdf) [low-quality pub, but expansive overview of the subject]
- "Stepwise Evolution of Nonliving to Living Chemical Systems.", Origins of Life and Evolution of the Biosphere, Volume 34, Issue 4, Aug 2004, Pages 371–389 (full-text .pdf)
- "The Origin of Cellular Life.", Bioessays, Volume 22, Issue 12, Dec 2004, Pages 1160-1170 (full-text .pdf)
- "The Origin of the Genetic Code: Theories and Their Relationships, A Review.", Biosystems, Volume 80, Issue 2, May 2005, Pages 175-184 (full-text .pdf)
- "The Origin and Evolution of the Genetic Code: Statistical and Experimental Investigations.", Robin D. Knight, Ph.D. Dissertation, June 2001.
The bar of evidence would continue to be elevated, just as Behe demonstrated with respect to the immune system (blood clotting cascade = BCC, irreducible complexity = IC):
The BCC arguments can be found throughout IDC websites. One of the most well-informed responders to these arguments is Andrea Bottaro. Last year, as more evidence came in that transposons were involved in the human immune response, Dr. Bottaro put together the pieces and completely refuted the claim of IC as it applies to BCC. How did Prof. Behe respond? By moving the goalposts -- not in any way denying the evidence, but demanding a mutation-by-mutation account of the pathways involved. Thus, he undercuts his own argument by rendering the burden of proof unattainable by any scientific pursuit.Creationists will continue to place ridiculous burdens of proof upon science, while completely refusing to provide positive evidence of their own (because, of course, they have none). Their arguments are, 99.9% of the time, anti-evolutionary in nature, because there are no sound pro-creationism arguments. And, as Judge Jones articulately pointed out, this fallacy of logic is the false dilemma: "If you're wrong, then I'm right."
The court in McLean stated that creation science rested on a "contrived dualism" that recognized only two possible explanations for life, the scientific theory of evolution and biblical creationism, treated the two as mutually exclusive such that "one must either accept the literal interpretation of Genesis or else believe in the godless system of evolution," and accordingly viewed any critiques of evolution as evidence that necessarily supported biblical creationism.Typical creationist stupidity.
What knowledge do they produce? What cures do they offer? What technology have they manufactured? None. Nada. Zilch. They deal only in ignorance. They give nothing in the way of evidence or argument, and ask for the world in return. When mountains of evidence are presented to them, like in the papers above, they ignore them and dodge the facts entirely.
All they offer are bad arguments against evolution, distortions of facts, and philosophical pleas based on unsound premises. Their desperation is evidenced clearly by the depths to which they descend in order to preserve their silly superstitious religious beliefs. And desperate they ought to be, because evolution has irreparably demolished the validity of the ancient creationist myths forever.
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Technorati tags: Intelligent Design, Evolution, Creationism
