Fragmented deoxyribonucleic acid could be extractable from Mars’s surface rocks
Bibliographic record
Abstract
Detecting biomolecules in rocks is vital for understanding life’s evolution on Earth and its possible existence on Mars. The Curiosity rover measured Total Organic Carbon (TOC) levels of 201–273 ppm in 3500 million years (Ma)-old Martian mudstones exposed to radiation for 78 ± 30 Ma. Here we investigate whether deoxyribonucleic acid (DNA), a unique biological polymer, can be recovered under comparable conditions. We extracted and sequenced DNA from terrestrial sedimentary rocks with TOC ranging from 182 to 63,000 ppm, yielding 184,000 to 3.8 million nucleobases from a 0.5 g rock sample. After exposure to 10.45 MGy of gamma radiation, equivalent to 136 Ma on the Martian surface, we measured a radiolytic constant of K = 0.17 MGy⁻¹ in microbialite (2800-year-old) and oxide iron formation (2930 Ma old) samples. Despite fragmentation, 1.48–8.45% of sequences remained taxonomically identifiable, demonstrating that DNA fragments can persist in rocks for over 100 Ma. Taxonomically identifiable DNA can be recovered from terrestrial rocks containing as little as 182 ppm of total organic carbon after exposure to radiation equivalent to 136 million years on Mars, suggesting that biosignatures could remain detectable.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".