Did Iron Suppress Eukaryote Emergence and Early Radiation?
Bibliographic record
Abstract
The last eukaryotic common ancestor (LECA) is widely thought to have been an oxygen-respiring organism, arising through endosymbiosis when a free-living bacterium became the mitochondrion. Owing to the mitochondrion s central metabolic task of oxidative phosphorylation, oxygen availability has long been a hypothesized driver of eukaryogenesis. However, this hypothesis is challenged by a temporal disconnect, spanning several hundred million years, between the earliest geochemical evidence for oxygen in the environment (~3.2-2.5 Ga) and the oldest widely accepted eukaryotic fossils (~1.7 Ga). Notably, the earliest candidate eukaryotes appear contemporaneous with the cessation of major iron deposits and rise of sulfide- and sulfate-rich marine sediments in coastal environments. Here, we integrate Proterozoic surface geochemical records with the microbial biochemistry of iron to examine potential environmental constraints on early eukaryotic evolution. Iron bioavailability exerts complex and often antagonistic effects on both aerobic and anaerobic microbial lineages that contributed to LECA. Elevated iron levels likely disrupted cellular homeostasis, particularly by destabilizing labile iron pools and promoting oxidative damage to bacterial lipids. The programmed cell death pathways known as ferroptosis, which is widespread among eukaryotic lineages, may trace its origins to iron-rich conditions in Archaean and Paleoproterozoic seawater and LECA. Our findings challenge oxygen-centered paradigms of eukaryogenesis and reframes the long-recognized temporal gap as a consequence of iron-mediated physiological constraints.
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 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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".