Key Step in Origin of Life Declared
The popular “RNA World” scenario for the origin of life has long suffered from a big hurdle: the implausibility of getting the key components of RNA building blocks, called nucleotides, from joining together. Each nucleotide requires a ribose sugar, a pyrimidine base, and a phosphate group. Now, a team publishing in Nature tried a new approach and got it to work.1 Long-time origin of life researcher Jack Szostak calls it “one of the great advances in prebiotic chemistry.”2 New Scientist announced the success with the headline, “Molecule of life emerges from laboratory slime.”
OK, what really happened? Powner et al bypassed the usual approach of trying to synthesize ribose and pyrimidine separately and then getting them to link up spontaneously – a seemingly insurmountable hurdle (see, for instance, 11/05/2004). Instead, they introduced phosphate early and found that the two building blocks could grow up together from a compound called 2-aminooxazole through a series of “plausible intermediates” (that is, chemicals that might form naturally). Then, they found that a gentle bath of UV radiation preserved the desired products while destroying the zoo of cross-reactions that normally cloud the astrobiologist’s flasks with tarry gunk.
Szostak [Howard Hughes Medical Institute] said that researchers had been about to give up on RNA because its parts fail to link up naturally. “The idea that a molecule as complex as RNA could have assembled spontaneously has therefore been viewed with increasing scepticism,” he wrote for Nature’s review of the paper. “This has led to a search for alternative, simpler genetic polymers that might have preceded RNA in the early history of life.”
But Powner et al. revive the prospects of the ‘RNA first’ model by exploring a pathway for pyrimidine ribonucleotide synthesis in which the sugar and nucleobase emerge from a common precursor (Fig. 1b). In this pathway, the complete ribonucleotide structure forms without using free sugar and nucleobase molecules as intermediates. This central insight, combined with a series of additional innovations, provides a remarkably efficient solution to the problem of prebiotic ribonucleotide synthesis.
Bad luck with tarry gunk by previous researchers led them to keep the synthesis of ribose and pyrimidine separate, else they got a nasty surprise: a “chemical combinatorial explosion: the synthesis of millions of different organic compounds, of which the desired biological precursor molecules would be a vanishingly small fraction.” Many of these competed for resources and linked onto the desired molecules. Powner’s group found that phosphate and UV prevent the gumming up of the works. The UV light acts like a cleaner but doesn’t harm the RNA reactants.
How realistic is this for the early earth? The authors’ diagram includes 13 reaction steps and as many required molecules. Szostak realizes it is only a start:
Of course, much remains to be done. We must now try to determine how the various starting materials could have accumulated in a relatively pure and concentrated form in local environments on early Earth. Furthermore, although Powner and colleagues’ synthetic sequence yields the pyrimidine ribonucleotides, it cannot explain how purine ribonucleotides (which incorporate guanine and adenine) might have formed. But it is precisely because this work opens up so many new directions for research that it will stand for years as one of the great advances in prebiotic chemistry.
Additional questions remain: how did the nucleotide sugars become one-handed? How did they link together into chains? What was the origin of the genetic code? But at least one huge hurdle has been surmounted, it seems. Surprisingly, Astrobiology Magazine said nothing about this (yet). New Scientist was one of the few mentioning it. That article quoted another origin-of-life researcher saying, “It’s a great leap forward that demonstrates how prebiotic RNA molecules may have assembled spontaneously from simple and presumably relatively abundant constituents.”
1. Powner, Gerland and Sutherland, “Synthesis of activated pyrimidine ribonucleotides in prebiotically plausible conditions,” Nature 459, 239-242 (14 May 2009) | doi:10.1038/nature08013.
2. Jack W. Szostak, “Origins of life: Systems chemistry on early Earth,” Nature 459, 171-172 (14 May 2009) | doi:10.1038/459171a.
We do try to be charitable to the evolutionists. We let their own Darwin Party colleagues congratulate each other before turning the lights on. Cornelius Hunter, an intelligent-design scientist with a PhD in biochemistry, was also charitable on his blog Darwin’s God, but had to state that abiogenesis is one of the “silliest of all the icons of evolution.” He said that “The bad news for evolutionists is that this finding does nothing to mitigate enormous problems with the whole idea of abiogenesis,” even though this finding “does improve the picture slightly”. Some of the big problems that remain are chirality (the handedness of the molecules), the implausibility of believing the required molecules could have been concentrated in their pure form, and the ordering of the building blocks into a meaningful sequence (the “configurational entropy” problem described in detail in The Mystery of Life’s Origin by Thaxton, Bradley and Olsen).
In addition, the usual criticisms can be brought to bear about the experimental approach: investigator interference, and the fine-tuning of conditions for a predetermined goal. Is this not really a lesson on intelligent design? “Prebiotic” molecules could not have cared less about forming life, because molecules cannot care at all. Another criticism is that “plausibility” is a subjective criterion. However plausible this sequence appears to the authors, it flies in the face of approaches by others who seek the origin of life at deep sea vents or deep in the earth (e.g., Michael Russell, 12/03/2004). Those researchers are likely to find this paper highly implausible.
More importantly, the building blocks are not the main issue. Give the evolutionists an ocean full of nucleotides and proteins, and they will still not have life. This can be shown by a simple experiment. In The Case for a Creator, Jonathan Wells describes an experiment a high school student could do. Take a living cell in a test tube, poke it, and let the ingredients all leak out. Now, you have a confined space with all the ingredients for life present – because they were once part of a living cell. The situation is far more ideal than the primordial soup the Darwinist chefs keep trying to cook up. In the test tube, the ingredients are all one-handed and in the proportions required. But does anyone believe for a minute that these building blocks will spontaneously reassemble into another living cell? Dr. A. E. Wilder-Smith described another simple home experiment. A sardine can has all the ingredients for life, because the sardines were once alive. If anyone suspected that life would spontaneously re-emerge from the building blocks in a sardine can, he argued, the whole food industry would be cast into a panic. The FDA and the USDA all depend on abiogenesis not being true. If you had to worry that unknown life-forms would spontaneously evolve under perfect conditions in canned goods, even if only once in a million times, you could not trust the cans on your shelf. But insert the information for life into that same sardine can, like one cell of E. coli, and the can will nearly burst with life in a matter of hours. Thank God spontaneous generation is false (as Pasteur proved).
But can’t the evolutionists argue that their “scientific approach” is slowly eroding the gaps in our knowledge? Isn’t intelligent design a “god-of-the-gaps” argument that brings science to a halt? Isn’t it better to keep chipping away at the unknowns by the scientific method? If you are unable to answer this question, you need to do some homework. First, review the arguments of two giants of origin-of-life research whose arguments falsified each other, Robert Shapiro (02/15/2007) and Leslie Orgel (01/26/2008). Then see whether any (if any) of the problems in the RNA World scenario outlined by Gerald Joyce in the 07/11/2002 entry are solved by this announcement (#6, perhaps?). Then read a couple of penetrating articles by creationist writers about filling gaps with stories: one about terms as place-holders for ignorance on BreakPoint by Regis Nicoll, and one on God-of-the-gaps on Creation.com by Lael Weinberger (don’t miss some of the best material in the footnotes). Sorry for the homework assignment, but no good teacher does all the thinking for the student.