Bibliographic record
Abstract
BACKGROUND: Despite great advances in clarifying the family tree of life, it is still not agreed where its root is or what properties the most ancient cells possessed--the most difficult problems in phylogeny. Protein paralogue trees can theoretically place the root, but are contradictory because of tree-reconstruction artefacts or poor resolution; ribosome-related and DNA-handling enzymes suggested one between neomura (eukaryotes plus archaebacteria) and eubacteria, whereas metabolic enzymes often place it within eubacteria but in contradictory places. Palaeontology shows that eubacteria are much more ancient than eukaryotes, and, together with phylogenetic evidence that archaebacteria are sisters not ancestral to eukaryotes, implies that the root is not within the neomura. Transition analysis, involving comparative/developmental and selective arguments, can polarize major transitions and thereby systematically exclude the root from major clades possessing derived characters and thus locate it; previously the 20 shared neomuran characters were thus argued to be derived, but whether the root was within eubacteria or between them and archaebacteria remained controversial. RESULTS: I analyze 13 major transitions within eubacteria, showing how they can all be congruently polarized. I infer the first fully resolved prokaryote tree, with a basal stem comprising the new infrakingdom Glidobacteria (Chlorobacteria, Hadobacteria, Cyanobacteria), which is entirely non-flagellate and probably ancestrally had gliding motility, and two derived branches (Gracilicutes and Unibacteria/Eurybacteria) that diverged immediately following the origin of flagella. Proteasome evolution shows that the universal root is outside a clade comprising neomura and Actinomycetales (proteates), and thus lies within other eubacteria, contrary to a widespread assumption that it is between eubacteria and neomura. Cell wall and flagellar evolution independently locate the root outside Posibacteria (Actinobacteria and Endobacteria), and thus among negibacteria with two membranes. Posibacteria are derived from Eurybacteria and ancestral to neomura. RNA polymerase and other insertions strongly favour the monophyly of Gracilicutes (Proteobacteria, Planctobacteria, Sphingobacteria, Spirochaetes). Evolution of the negibacterial outer membrane places the root within Eobacteria (Hadobacteria and Chlorobacteria, both primitively without lipopolysaccharide): as all phyla possessing the outer membrane beta-barrel protein Omp85 are highly probably derived, the root lies between them and Chlorobacteria, the only negibacteria without Omp85, or possibly within Chlorobacteria. CONCLUSION: Chlorobacteria are probably the oldest and Archaebacteria the youngest bacteria, with Posibacteria of intermediate age, requiring radical reassessment of dominant views of bacterial evolution. The last ancestor of all life was a eubacterium with acyl-ester membrane lipids, large genome, murein peptidoglycan walls, and fully developed eubacterial molecular biology and cell division. It was a non-flagellate negibacterium with two membranes, probably a photosynthetic green non-sulphur bacterium with relatively primitive secretory machinery, not a heterotrophic posibacterium with one membrane.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 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".