self-cleaving ribozyme Archives - Astrobiology

Evidence for ribozyme mass extinction. (A) Abundance distribution across all ten known small self-cleaving ribozyme families, showing the hammerhead's 91% dominance, a pattern characteristic of disaster taxa following mass extinction events. (B) Circular phylogeny of 80,548 unique hammerhead sequences colored by host taxonomic group. The star-like topology is consistent with post-bottleneck radiation, and the interspersion of distantly related host phyla around the tree reflects repeated independent colonization events rather than co-speciation, consistent with horizontal transfer of a single dominant survivor lineage. (C) Null distribution tests for Tajima's D (left) and Fu's Fs (right), each based on 10,000 coalescent replicates (n = 200, S = 40). Blue and orange histograms show the null distributions under neutral expectations; red dashed lines indicate the observed values (D = +2.28, upper-tail p = 0.013; Fs = −618.0, p < 0.0001). Observed D falls in the extreme upper tail (98.7% of null replicates below observed), indicating deep hierarchical structure; observed Fs falls far below any null replicate, indicating massive haplotype excess. The discordance between positive D and extremely negative Fs is diagnostic of ancient divergence preserved through a bottleneck followed by rapid within-lineage expansion. Full-sample values (n = 5,036) are D = +3.79, Fs = −690.8. -- biorxiv.org

Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Origin & Evolution of Life, Status Report

A Ribozyme Mass Extinction At The RNA-cellular Boundary And Its Potential Imprint On The Genetic Code

by Keith CowingApril 13, 2026April 13, 2026

The transition from the RNA world to cellular life remains one of the least understood events in the history of biology.