Towards RNA life on Early Earth: From atmospheric HCN to biomolecule production in warm little ponds
Bibliographic record
Abstract
<p><span>The origin of life on Earth involves the early appearance of an information-containing molecule such as RNA. Warm little ponds are ideal sites for the emergence of RNA, as their periodic wet-dry cycles provide conditions favorable for polymerization </span><span>(e.g. Da Silva et al. 2015, Ross & Dea</span><span>mer 2016</span><span>)</span><span>.</span></p><p><span> How did the</span><span> building blocks of </span><span>RNA</span> <span>come to be in warm little ponds </span><span>on early Earth? Is it necessary that they were delivered by meteorites or interplanetary dust? Or was early Earth capable of producing </span><span>them</span><span> on its own? In the latter case, </span><span>the process </span><span>can begin</span><span> with the production of HCN in the atmosphere, which </span><span>reacts in aqueous solution to produce several </span><span>key</span><span> RNA </span><span>precursors such as nucleobases, ribose, and 2-aminooxazole</span> <span>(e.g. Yi et al. 2020, Hill & Orgel 2002, Becker et al. 2018, Powner et al. 2009).</span></p><p><span> Here, we construct a robust physical and non-equilibrium chemical model of the early Earth atmosphere in which lightning and external UV-driven chemistry produce HCN. The atmosphere is supplied with hydrogen from impact degassing of meteorites, sourced with water evaporated from the oceans, carbon dioxide from volcanoes, and methane from undersea hydrothermal vents. This </span><span>model </span><span>allows us to calculate the rain-out of HCN into warm little ponds (WLPs). We then use a comprehensive sources and sinks numerical model to compute the resulting abundances of nucleobases, ribose, and nucleotide precursors such as 2-aminooxazole resulting from aqueous and UV-driven chemistry within them. We find that at 4.4 bya (billion years ago) peak adenine concentrations in ponds can be maintained at ∼2.8μM for more than 100 Myr. Meteorite delivery of adenine to WLPs produce similar peaks </span><span>in concentration, but are destroyed within months by UV photodissociation, seepage, and hydrolysis. The early evolution of the atmosphere is dominated by the decrease of hydrogen due to falling impact rates and atmospheric escape, and the rise of oxygenated species such as OH from H<sub>2</sub>O photolysis. Our work points to an early origin of RNA on Earth within ~200 Myr of the Moon-forming impact.</span></p>
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".