Tuesday, 9 August 2022

God of the Gaps News - Creationism's Little Skrinking God Just Got a Lot Smaller

Olivine basalt
Scientists announce a breakthrough in determining life's origin on Earth—and maybe Mars

The basic problem with Creationism's favourite 'argument' - 'the God of the Gaps' - is not only that it is based on two fallacies - the argument from ignorant incredulity and the false dichotomy fallacies, but also that it tends to disappear every time the gap is subjected to scientific scrutiny.

That's exactly what has just happened with one of their favourite gaps - the origin of living organisms, which they always conflate with the theory of evolution of which it is not and never was a part. Evolution is what happened after ‘life’, or more precisely, self-replication, got started.

Essentially, living organisms can trace their origins back to a self-replicating molecule because once that had arisen, everything else follows naturally by Darwinian natural selection acting on small variations in the copies (the sieve of natural selection acting on each generation to filter out the best at producing copies of themselves and remove those least able to). Just such a molecule known to exist is a short length of RNA which has been shown to self-catalyse copies of itself in a mixture of nucleotides, by nothing more complex than the operation of the basic laws of chemistry.

But the question is, how did such a molecule first assemble?

That question has now been answered by a team led by Elisa Biondi of the Foundation for Applied Molecular Evolution, Alachua, FL, USA with colleagues from Firebird Biomolecular Sciences LLC, Alachua, FL, USA and the Department of Geological Sciences, University of Colorado, Boulder, CO, USA. The team published their findings open access, in the journal Astrobiology recently.

They have shown that chains of RNA will form on the glass-like basalt, that would have been abundant on the young Earth due to impacts by meteorites and volcanic activity. Meteorites would also have delivered nickel, which catalyses an early stage of the reactions and iron, which would have reduced the atmosphere and removed potentially destructive oxygen, creating exactly the conditions which a simple experiment can show, will produce short chains of RNA. Since there are only 4 nucleotides involved in RNA, the probability of a chain which can self-replicate tends towards certainty in conditions in which a very large number of RNA chains are being produced.

Read more:
The strange thing about Basalt - Geoscience Education & Outreach.

An article in Phys.Org. explains the significance of this finding:
Led by Elisa Biondi, the study [Foundation] shows that long RNA molecules, 100-200 nucleotides in length, form when nucleoside triphosphates do nothing more than percolate through basaltic glass.

Basaltic glass was everywhere on Earth at the time. For several hundred million years after the Moon formed, frequent impacts coupled with abundant volcanism on the young planet formed molten basaltic lava, the source of the basalt glass. Impacts also evaporated water to give dry land, providing aquifers where RNA could have formed.

Stephen Mojzsis, co-author Earth scientis
Department of Geological Sciences
University of Colorado, Boulder, Colorado, USA.
The same impacts also delivered nickel, which the team showed gives nucleoside triphosphates from nucleosides and activated phosphate, also found in lava glass. Borate (as in borax), also from the basalt, controls the formation of those triphosphates.

The beauty of this model is its simplicity. It can be tested by highschoolers in chemistry class,. Mix the ingredients, wait for a few days and detect the RNA.

Jan Špaček, not involved with the study
Deve loper of instruments to detect alien genetic polymers on Mars
The same impactors that formed the glass also transiently reduced the atmosphere with their metal iron-nickel cores. RNA bases, whose sequences store genetic information, are formed in such atmospheres. The team had previously showed that nucleosides are formed by a simple reaction between ribose phosphate and RNA bases.

For example, borate manages the formation of ribose, the 'R' in RNA.

Stephen A. Benner, co-author
Foundation for Applied Molecular Evolution
Alachua, Florida, USA.
The same rocks resolve the other paradoxes in making RNA in a path that moves all of the way from simple organic molecules to the first RNA. This path starts from simple carbohydrates that could "not not" have formed in the atmosphere above primitive Earth. These were stabilized by volcanic sulfur dioxide, and then rained to the surface to create reservoirs of organic minerals.

Thus, this work completes a path that creates RNA from small organic molecules that were almost certainly present on the early Earth. A single geological model moves from one and two carbon molecules to give RNA molecules long enough to support Darwinian evolution.

The team give more detail in the abstract to their open access paper in Astrobiology:

Reported here are experiments that show that ribonucleoside triphosphates are converted to polyribonucleic acid when incubated with rock glasses similar to those likely present 4.3–4.4 billion years ago on the Hadean Earth surface, where they were formed by impacts and volcanism. This polyribonucleic acid averages 100–300 nucleotides in length, with a substantial fraction of 3′,-5′-dinucleotide linkages. Chemical analyses, including classical methods that were used to prove the structure of natural RNA, establish a polyribonucleic acid structure for these products. The polyribonucleic acid accumulated and was stable for months, with a synthesis rate of 2 × 10−3 pmoles of triphosphate polymerized each hour per gram of glass (25°C, pH 7.5). These results suggest that polyribonucleotides were available to Hadean environments if triphosphates were. As many proposals are emerging describing how triphosphates might have been made on the Hadean Earth, the process observed here offers an important missing step in models for the prebiotic synthesis of RNA.

Of course, there is still much work to be done to show how self-replicating molecules became enclosed in membranes, but this work shows that the beginnings of 'life' on Earth require no more than the operation of physics and chemistry followed by the inevitable process of evolution by natural selection which would have slowly improved on the basic model, to produce whatever gave the most copies by being best able to exploit the limited natural resources available. The result, several billion years later, is the amazing biodiversity we now have on the planet, all tracing its origins back to these earliest self-replicating molecules.

Thank you for sharing!

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