Another RNA World ‘Missing Link’ Experiment Misses the Point
Magic droplets overcome one hurdle with help from humans, but so what?
If you add highly improbable ingredients to water droplets, then zap them with 5,000 volts of electricity at 500 °F, you might get some of them to bind together long enough to measure. What does that have to do with the origin of life?
In the latest origin-of-life circus act, three Koreans got their ‘scenario’ published in the Proceedings of the National Academy of Sciences (USA), hoping that it would cheer up the researchers still clinging to the problematic “RNA World” hypothesis.
One hypothesis concerning the origin of life postulates an RNA world that existed on Earth before modern cells arose (1 [a reference to the late Leslie Orgel’s 1998 paper]). According to this hypothesis, RNA stored genetic information and catalyzed chemical reactions in primitive cells (2, 3). However, a major missing link has been how to construct from simpler molecules the ribonucleosides, which are the building blocks of RNA (1–3). This challenge seems quite daunting because the making of ribonucleosides in a water solution from ribose and some suitable nucleobase, such as the purines adenine and guanine, and the pyrimidines uracil and cytosine, is thermodynamically uphill (4, 5). Recently, possible routes for the prebiotic synthesis of purine and pyrimidine ribonucleosides were studied by bypassing the biological synthesis mechanism (5–8). These routes demand different environments, although it might be more favorable if purine and pyrimidine ribonucleosides could be condensed in the same environment for the fabrication of RNA. Moreover, these mechanisms require complex, sequential reactions with reaction times in the range of days, which may make them less relevant for creating a prebiotic chemistry in which RNA could develop. As described below, we present an alternative route for the synthesis of ribonucleosides that seems to be sufficiently mild and general that it might have played a role in turning simpler molecules into biomolecules.
Hoping to make life easier for mindless molecules, these three meditate on possibility thinking (notice the words could, might). Then they ran some experiments that got RNA nucleosides to form in microdroplets, provided they fortified the droplets with ribose and nucleobases, and zapped the droplets with electricity and heat. They got the nucleosides A, C, and U, but not G (guanine), but they were happy to get the fake nucleoside “I” (inosine). Then they envisioned a misty early earth where the magic might happen without the help of prefabricated chemicals, nozzles, mass spectrometers and intelligent human beings.
Because mists, clouds, and sprays are thought to be common on early Earth, these findings provide a possible missing link as to how the RNA world came about.
Apparently these ingredients will bind, in the presence of magnesium ions, if the droplets are small enough. The physics inside microdroplets (which they made by pumping droplets through a syringe), if sufficiently hot and electrified, can overcome the thermodynamic barrier (using Mg2+ as a catalyst) and force the ribose and nucleobases to bind into nucleosides, the “building blocks of RNA.” However, nothing was said about these hurdles:
- They did not get actual RNA to form.
- They did not specify how ribose would form— a major hurdle in OOL, because it falls apart in water.
- They did not specify how single-handed ribose would form (homochirality).
- They did not indicate how nucleobases would form. They assumed the existence of ribose and nucleosides.
- They did not specify how phosphate groups would become associated with the nucleosides to turn them into nucleotides needed for RNA.
- They did not specify the lifetimes of the nucleosides after they somehow escape from their microdroplet cages.
- They did not identify harmful reaction products that would destroy the nucleosides.
- They did not mention the harmful effects of oxygen.
- They did not help the circus acts that postulate building blocks of life forming in deep-sea vents.
Those are just for starters. The fallacy that makes this experiment meaningless is that it ignores the information problem. Even if OOL circus acts could take care of all these challenges, they would be faced with the overwhelming question: what is the source of the information that puts these building blocks into a coded language? RNA has to function somehow. Most RNAs coaxed into existence by intelligent researchers are short, and few “ribozymes” do anything beyond cleaving themselves or other molecules. How would you like to build a house with one tool, a robotic saw that cuts everything it encounters to pieces, including itself?
These circus clowns speak glibly about RNA storing “genetic information” but have no idea where that information comes from. Information is the most important thing in life. If you don’t deal with that problem in your speculating about origins, all your busy work is for nothing! There is your National Academy of Sciences for you, publishing more meaningless nonsense about irrelevant questions.
To be cured of OOL folly, watch the video clips at Illustra’s Origin film site, and read Stephen Meyer’s book, Signature in the Cell. And since the above Korean researchers’ first reference was to Orgel (Stanley Miller’s buddy), we encourage our readers to look at his last will and testament before he died: Pigs don’t fly, and life doesn’t just happen (1/26/08).