A phylogeography of the second plague pandemic revealed through the analysis of historical <i>Y. pestis</i> genomes
Bibliographic record
Abstract
The second plague pandemic (14th - 18th century AD), caused by the bacterium Yersinia pestis , is infamous for its initial wave, the Black Death (1346-1353 AD), and its repeated scourges in Europe and the vicinity until the Early Modern Era. Here, we report 32 ancient Y. pestis genomes spanning the 14th to 17th century AD through the analysis of human remains from nine European archaeological sites. Our data support an initial entry of the bacterium from Eastern Europe and the absence of genetic diversity during the Black Death as well as low diversity during local outbreaks thereafter. Moreover, analysis of post-Black Death genomes shows the diversification of a Y. pestis lineage into multiple genetically distinct clades that may have given rise to more than one disease reservoir in, or close to, Europe. Finally, we show the loss of a genomic region that includes virulence-associated genes in strains associated with late stages of the second plague pandemic (17th - 18th century AD). This deletion could not be detected in extant strains within our modern dataset, though it was identified in a today-extinct lineage associated with the first plague pandemic (6th - 8th century AD), suggesting convergent evolution during both pandemic events.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".