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Evidence record

How old is the plague?

Every sentence on the exploration belongs to at least one claim below. Each says what kind of statement it is, what it rests on, what the evidence does not establish, and how far it was checked. Nothing here is a score, and none of it is a verdict on a belief or a theory.

Last checked 24 September 2026.

  • Source checked: 31
  • A judgement, not a fact: 10
  • Partly checked: 4

If something here is wrong, misquoted, out of date or unfair, write to support@unknownoceans.com and give the claim number, which does not change.

What the question takes for granted

A dating question answered by molecular archaeology rather than by texts. The page rests on four ancient DNA studies and on one inference drawn from them: that the age of a lineage, read off sequenced genomes, is the age of the disease. The Bronze Age strains lack a gene the later ones have, so what was old is the bacterium rather than the illness history records.

  • DNA in a tooth records the infection its owner had when they died

    Established

    Dental pulp is sterile in life and durable after death, which is why it is the material every study here works from. Drancourt and others proposed it in 1998 and recovered plague DNA from sixteenth-century teeth; Bos and others sequenced the Black Death from the same tissue.

  • The Bronze Age bacterium and the medieval one are the same disease

    Contested

    They are the same species by genome, but Rasmussen and others find the early strains lack ymt and conclude they could not cause bubonic plague. The page says so: what is five thousand years old is the lineage, not the illness that history remembers.

  • The first plague epidemic anyone recorded is the sixth-century one

    Established

    Rasmussen and others take the First Pandemic, beginning with the Plague of Justinian in 541 AD, as the earliest documented one, and note that earlier outbreaks such as the Plague of Athens cannot be confidently attributed to Y. pestis.

How the question is labelled

Claim: Reading a pandemic out of teeth

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: Plague

Kind
Framing. Signposting. It asserts nothing a source could check.

The question

Claim: The bacterium behind the Black Death was in human bodies three thousand years before the first plague pandemic anyone recorded.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoSummary

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: we report the oldest direct evidence of Yersinia pestis identified by ancient DNA in human teeth from Asia and Europe dating from 2,800 to 5,000 years ago ... plague infection was endemic in the human populations of Eurasia at least 3,000 years before any historical recordings of pandemics

    The oldest positive graves, about 2800 BC, to the Plague of Justinian in 541 AD is about 3,330 years, which the paper rounds down to at least 3,000.

What this does not establish

The Bronze Age strains are basal to every later one, and Rasmussen and others conclude they could not cause bubonic plague. The species is the same; the disease was not.

Later work looked for

Crossref and Europe PMC, 2016 on, "ancient Yersinia pestis genome": Susat and others 2021 report an older genome still, from a burial in Latvia dated 5,300 to 5,050 years before the present. The three thousand year gap widens rather than closes.

Corrected

24 September 2026. Previously: “The bacterium behind the Black Death was in human bodies three thousand years before the first epidemic anyone recorded.” Rasmussen and others measure the gap to “any historical recordings of pandemics”, the first being Justinian’s in 541. The same paper says earlier outbreaks such as the Plague of Athens were recorded but cannot be confidently attributed to Y. pestis, so “the first epidemic” named the wrong thing.

Claim 3 · checked 24 September 2026 · AI-assisted audit

Claim: DNA recovered from the teeth of Bronze Age skeletons carries Yersinia pestis, five thousand years old and lacking the gene that lets the later strains spread through fleas.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoSummary; Highlights; Results

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: ancient DNA in human teeth from Asia and Europe dating from 2,800 to 5,000 years ago ... The ymt gene was acquired before 951 cal BC, giving rise to transmission via fleas

What this does not establish

Five thousand years is the paper’s own rounding, and its title. The oldest bodies it sequenced are two Afanasievo burials dated 2794 and 2782 cal BC; the 5,783 year figure belongs to the estimated common ancestor of all Y. pestis rather than to any skeleton.

Later work looked for

Crossref and Europe PMC, 2016 on, "ancient Yersinia pestis genome": Susat and others 2021 reconstruct a genome from a hunter-fisher-gatherer dated 5300 to 5050 cal BP, which is older than anything in the 2015 sample and also lacks the later virulence profile.

Claim 4 · checked 24 September 2026 · AI-assisted audit

Claim: The history of a disease can now be read directly rather than inferred from descriptions of symptoms.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page’s reading of what the four studies below have in common. Each identifies a pathogen from its own DNA rather than from a chronicle.

What this does not establish

It holds for infections that reach the blood and leave DNA in bone or teeth, which the page says later on.

Claim 5 · checked 24 September 2026 · AI-assisted audit

Claim: Historical epidemics used to be identified from written descriptions of symptoms, which is unreliable

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

Only the abstract of Drancourt and others was served to this environment; the body of the paper was not read. The abstract states the point about historical clinical observations directly.

Claim 6 · checked 24 September 2026 · AI-assisted audit

Claim: many diseases produce fever and death, and chroniclers were not diagnosticians

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page’s own gloss on why a written description is weak evidence. The cited source states the conclusion, not this reasoning for it.

Claim 7 · checked 24 September 2026 · AI-assisted audit

Claim: Ancient DNA changed that.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

A transition, carrying the page’s judgement that the method settled what texts could not. The Justinianic case below is the worked example.

Claim 8 · checked 24 September 2026 · AI-assisted audit

Claim: The pathogen itself can be recovered, sequenced and placed on a family tree.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    A draft genome of Yersinia pestis from victims of the Black DeathAbstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: Here we report a reconstructed ancient genome of Yersinia pestis at 30-fold average coverage from Black Death victims securely dated to episodes of pestilence-associated mortality in London, England, 1348–1350. Genetic architecture and phylogenetic analysis indicate that the ancient organism is ancestral to most extant strains

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoResults

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: the two ancient strains (RISE505 and RISE509) falling basal to all other known strains of Y. pestis (100% bootstrap support)

What this does not establish

Recovery depends on preservation and on the pathogen having been in the blood. Coverage of the ancient genomes here ranges from a fraction of the genome to nearly all of it.

Later work looked for

Crossref, 2012 on, "ancient pathogen genome": capture and sequencing of ancient pathogen DNA has become routine since; nothing that changes the statement.

Claim 9 · checked 24 September 2026 · AI-assisted audit

What was recovered

Claim: What was recovered

Kind
Framing. Signposting. It asserts nothing a source could check.

Five thousand years of it

Claim: Five thousand years of it

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoTitle; Summary

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years Ago ... human teeth from Asia and Europe dating from 2,800 to 5,000 years ago

What this does not establish

The round figure is the paper’s. The oldest sequenced individuals date to 2794 and 2782 cal BC, which is nearer 4,800 years.

Later work looked for

Crossref and Europe PMC, 2016 on: Susat and others 2021 report a genome dated 5300 to 5050 cal BP, so five thousand years is now a floor rather than a ceiling.

Claim 11 · checked 24 September 2026 · AI-assisted audit

Claim: A 2015 study screened the teeth of over a hundred Bronze Age individuals from Eurasia and found Yersinia pestis in seven of them, the oldest from graves dated to about 2800 BC.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoResults, first paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: We screened c. 89 billion raw DNA sequence reads obtained from teeth of 101 Bronze Age individuals from Europe and Asia ... and found that seven individuals carried sequences resembling Y. pestis ... the Afanasievo culture in Altai, Siberia (2782 cal BC, 2794 cal BC, n = 2)

What this does not establish

Seven of 101 screened. Genome coverage across the seven runs from 0.14 to 29.5 times, so not all seven carry the same weight of evidence.

Later work looked for

Crossref and Europe PMC, 2016 on, "prehistoric Yersinia pestis": further Neolithic and Bronze Age genomes have been published since, including Susat and others 2021; none revises these seven.

Claim 12 · checked 24 September 2026 · AI-assisted audit

Claim: That is three thousand years before the first historically recorded plague pandemic.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoSummary; Introduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Texts · Review of the field

    The source reads: plague infection was endemic in the human populations of Eurasia at least 3,000 years before any historical recordings of pandemics ... the First Pandemic, which started with the Plague of Justinian (541–544 AD)

    The oldest positive graves, about 2800 BC, to the Plague of Justinian in 541 AD is about 3,330 years, which the paper rounds down to at least 3,000.

What this does not establish

The gap is counted to the first documented pandemic. Earlier outbreaks such as the Plague of Athens are recorded, but the same paper says they cannot be confidently attributed to Y. pestis.

Corrected

24 September 2026. Previously: “That is three thousand years before the first historically recorded plague epidemic.” Rasmussen and others measure the gap to “any historical recordings of pandemics”, the first being Justinian’s in 541. The same paper says earlier outbreaks such as the Plague of Athens were recorded but cannot be confidently attributed to Y. pestis, so “the first epidemic” named the wrong thing.

Claim 13 · checked 24 September 2026 · AI-assisted audit

Claim: The bacterium was infecting people across Eurasia during the period of the great steppe migrations.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: the ancestor of extant Y. pestis strains was present by the end of the 4th millennium BC and was widely spread across Eurasia from at least the early 3rd millennium BC ... the Bronze Age in Europe and Asia was characterized by large-scale population movements, admixture, and replacements

  • Qualifies

    A 5,000-year-old hunter-gatherer already plagued by Yersinia pestisSummary

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026

    The source reads: The geographical and temporal distribution of the few prehistoric Y. pestis cases reported so far is more in agreement with single zoonotic events.

What this does not establish

The spread is read off seven infections from Siberia, Estonia, Russia, Poland and Armenia. Whether those add up to an epidemic or to scattered infections is the disagreement the page reports later.

Later work looked for

Europe PMC, 2016 on, "prehistoric plague Eurasia": Susat and others 2021 argue the prehistoric cases look like separate spillovers from animals. That reading is now on the page.

Claim 14 · checked 24 September 2026 · AI-assisted audit

Claim: Teeth are used because the pulp inside them is sterile and durable, a lasting refuge for a bacterium that was in the blood when its host died.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

Read from the abstract only; the body of Drancourt and others was not served to this environment. A lasting refuge was their hypothesis in 1998, and the recoveries since are what bore it out.

Claim 15 · checked 24 September 2026 · AI-assisted audit

And it could not yet be spread by fleas

Claim: And it could not yet be spread by fleas

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoResults; Highlights

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: In combination with the absence of ymt, these results strongly suggest that the ancestral Y. pestis bacteria in these early Bronze Age individuals were not transmitted by fleas.

What this does not establish

An inference from which genes are present in the sequenced genomes, not from any observation of transmission. The authors say larger samples are needed.

Later work looked for

Europe PMC, 2016 on, "ymt flea transmission Yersinia pestis": Susat and others 2021 report the same absence in an older genome and reach the same conclusion about transmissibility.

Claim 16 · checked 24 September 2026 · AI-assisted audit

Claim: The early strains lack a gene that later strains have.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoResults, virulence genes

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: We found all virulence genes to be present, except the Yersinia murine toxin (ymt) gene ... we identified a 19 kb region ... to be missing except in the youngest sample (RISE397, 951 cal BC)

What this does not establish

The gene is missing in six of the seven ancient samples. The seventh, and youngest, has it.

Later work looked for

Europe PMC, 2016 on, "ymt Yersinia pestis ancient genome": later genomes fill in the same picture; nothing that reverses it.

Claim 17 · checked 24 September 2026 · AI-assisted audit

Claim: It makes a protein that protects the bacterium inside a flea’s gut, which is what lets a flea carry it from one animal to the next.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoResults, virulence genes

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Research in microbes · Review of the field

    The source reads: The ymt gene encodes a phospholipase D that protects Y. pestis inside the flea gut, thus enabling this enteric bacteria to use an arthropod as vector; it further allows for higher titers of Y. pestis and higher transmission rates

What this does not establish

Rasmussen and others state the mechanism citing earlier work on ymt rather than testing it themselves. The classic blocked-flea story, where a biofilm plugs the insect’s gut, is a different mechanism that they attribute to other genes.

Claim 18 · checked 24 September 2026 · AI-assisted audit

Claim: Without it, flea transmission does not work.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

The gene is necessary, not sufficient. The same paper reports that flea transmission also depends on losses of function in pde2, pde3 and rcsA, and that the oldest sequenced strain carries only one of those.

Claim 19 · checked 24 September 2026 · AI-assisted audit

Claim: So these ancient infections spread another way, probably by breathing or by direct contact, and caused a different kind of disease.

Kind
Hypothesis. A proposed explanation, not an established one.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: based on the absence of crucial virulence genes ... these ancient ancestral Y. pestis strains likely did not have the ability to cause bubonic plague, only pneumonic and septicemic plague

What this does not establish

Proposed from the genes the strains carry, not from any record of how anyone caught it. The page’s "probably" is the paper’s "likely".

Other readings

Susat and others read the scattered prehistoric cases as separate infections caught from animals, which would make the route the same and the spread much smaller.

Claim 20 · checked 24 September 2026 · AI-assisted audit

Claim: The gene appears in strains from about a thousand BC onward.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoResults, virulence genes

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: our data indicate that the ymt gene was not present in Y. pestis before 1686 cal BC (n = 6), while after 951 cal BC, it is found in 97.8% of the strains (n = 140), suggesting a late and very rapid spread of ymt

What this does not establish

The bracket is set by two dated samples: absent at 1686 cal BC, present at 951 cal BC. Nothing between those dates has been sequenced.

Later work looked for

Europe PMC, 2016 on, "ymt acquisition date Yersinia pestis": later genomes have not moved the bracket in a way that changes "about a thousand BC".

Claim 21 · checked 24 September 2026 · AI-assisted audit

Claim: A sequence of genetic changes, dated, that turned one disease into another.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page closing the passage on what the gene did. The paper describes a sequence of changes, of which the acquisition of ymt is one: a mutation in pla and a loss of flagellin genes are others.

What this does not establish

Dated by the calibrated dates of the bodies the strains came from, which is a handful of points on a three thousand year line.

Corrected

24 September 2026. Previously: “A specific evolutionary step, dated, that turned one disease into another.” The page made the acquisition of ymt the single switch. Rasmussen and others report a temporal sequence of changes, and say flea transmission also depends on losses of function in pde2, pde3 and rcsA.

Claim 22 · checked 24 September 2026 · AI-assisted audit

Claim: What the genomes show

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: ~2800 BC

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

Two calibrated radiocarbon dates on the two oldest individuals.

Later work looked for

Europe PMC, 2016 on: older individuals have since been sequenced elsewhere, which does not alter this date.

Claim 24 · checked 24 September 2026 · AI-assisted audit

Claim: Yersinia pestis in human teeth in Eurasia, in a form that cannot be carried by fleas.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoResults

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: seven individuals carried sequences resembling Y. pestis ... In combination with the absence of ymt, these results strongly suggest that the ancestral Y. pestis bacteria in these early Bronze Age individuals were not transmitted by fleas.

What this does not establish

The flea conclusion is drawn from missing genes in the sequenced genomes, and the authors ask for larger samples before it is taken as confirmed.

Later work looked for

Europe PMC, 2016 on, "prehistoric Yersinia pestis ymt": Susat and others 2021 find the same in an older genome.

Claim 25 · checked 24 September 2026 · AI-assisted audit

Claim: ~1000 BC

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoResults, virulence genes

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: the ymt gene was not present in Y. pestis before 1686 cal BC (n = 6), while after 951 cal BC, it is found in 97.8% of the strains (n = 140)

What this does not establish

The rounded form of 951 cal BC, the date of the one ancient sample that carries the gene.

Later work looked for

Europe PMC, 2016 on: the bracket around the acquisition of ymt has not moved enough to change the rounding.

Claim 26 · checked 24 September 2026 · AI-assisted audit

Claim: The gene enabling flea transmission appears, and with it the possibility of the disease as later history knows it.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoHighlights; Discussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: The ymt gene was acquired before 951 cal BC, giving rise to transmission via fleas ... our data suggest that Y. pestis did not fully adapt as a flea-borne mammalian pathogen until the beginning of the 1st millennium BC, which precipitated the historically recorded plagues

What this does not establish

A possibility rather than an outbreak: the first epidemic anyone recorded is fifteen hundred years later.

Later work looked for

Europe PMC, 2016 on, "flea-borne transmission Yersinia pestis evolution": nothing that changes the dating of the acquisition.

Claim 27 · checked 24 September 2026 · AI-assisted audit

Claim: 541 AD

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

Claim 28 · checked 24 September 2026 · AI-assisted audit

Claim: The first recorded pandemic, under Justinian, confirmed by DNA from burials rather than from descriptions.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

The confirmation is that Y. pestis was present in these sixth-century burials in Bavaria. How far the pandemic reached, and how many it killed, is not settled by that.

Claim 29 · checked 24 September 2026 · AI-assisted audit

Claim: 1347 onward

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    A draft genome of Yersinia pestis from victims of the Black DeathIntroduction

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Texts · Review of the field

    The source reads: The Black Death of 1347–1351, caused by the bacterium Yersinia pestis ... provides one of the best historical examples of an emerging infection with rapid dissemination and high mortality

Claim 30 · checked 24 September 2026 · AI-assisted audit

Claim: The Black Death, whose strain has been sequenced from London burial grounds.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    A draft genome of Yersinia pestis from victims of the Black DeathAbstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: a reconstructed ancient genome of Yersinia pestis at 30-fold average coverage from Black Death victims securely dated to episodes of pestilence-associated mortality in London, England, 1348–1350

What this does not establish

One burial ground, East Smithfield, and four individuals. A draft genome rather than a complete one.

Later work looked for

Crossref, 2012 on, "Black Death Yersinia pestis genome": Spyrou and others 2022 trace the source of the pandemic to burials at Kara-Djigach and Burana in Kyrgyzstan dated 1338 to 1339. That extends the story backwards and leaves the London sequencing as it stands.

Claim 31 · checked 24 September 2026 · AI-assisted audit

The Black Death itself was sequenced

Claim: The Black Death itself was sequenced

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    A draft genome of Yersinia pestis from victims of the Black DeathAbstract

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: Here we report a reconstructed ancient genome of Yersinia pestis at 30-fold average coverage from Black Death victims

What this does not establish

A draft genome, from four victims of one London cemetery.

Later work looked for

Crossref, 2012 on: further medieval genomes have been sequenced since, including from the pandemic’s central Asian source; the 2011 draft is not superseded.

Claim 32 · checked 24 September 2026 · AI-assisted audit

Claim: In 2011 a draft genome was recovered from the teeth of victims buried in a London plague cemetery between 1348 and 1350, which identified the organism behind the Black Death directly rather than from chronicles.

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    A draft genome of Yersinia pestis from victims of the Black DeathAbstract; Results; Methods summary

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: Historical data indicate that the East Smithfield burial ground was established in late 1348 or early 1349 specifically for interment of Black Death victims ... A secure date for the East Smithfield site of 1348–1350 ... DNA from dental pulp was extracted

What this does not establish

The cemetery’s date is historical and archaeological; the identification is genetic. Four individuals carried enough DNA to sequence.

Later work looked for

Crossref, 2012 on, "East Smithfield Yersinia pestis": the identification has been confirmed and extended by later medieval genomes.

Claim 33 · checked 24 September 2026 · AI-assisted audit

Claim: The strain turned out to sit close to the ancestor of most plague lineages circulating today

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    A draft genome of Yersinia pestis from victims of the Black DeathResults, phylogenetics

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: The trees place the East Smithfield sequence close to the ancestral node of all extant human pathogenic Y. pestis strains (only two differences in 1,694 positions) and at the base of branch 1

What this does not establish

Close to the ancestor of the strains that infect people, which is not all Y. pestis: the Bronze Age strains sit further back still.

Later work looked for

Crossref, 2012 on, "Yersinia pestis phylogeny medieval": Rasmussen and others 2015 place older strains basal to all of these, which is what the rest of this page reports.

Claim 34 · checked 24 September 2026 · AI-assisted audit

Claim: and it carries no distinctive mutation that would explain the severity of that pandemic

Kind
Observation. Something measured or seen, as the named source reports it.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    A draft genome of Yersinia pestis from victims of the Black DeathAbstract; Results

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: Comparisons against modern genomes reveal no unique derived positions in the medieval organism, indicating that the perceived increased virulence of the disease during the Black Death may not have been due to bacterial phenotype

What this does not establish

Nothing found is not nothing there. The authors put it as no novel fixed point mutations detectable by the method they used, and note that gene loss, gene gain and rearrangement were not ruled out.

Later work looked for

Crossref, 2012 on, "Black Death virulence bacterial genome": no later work reports a distinctive medieval virulence mutation.

Claim 35 · checked 24 September 2026 · AI-assisted audit

Claim: So the virulence of the Black Death is probably not explained by the pathogen being different.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    A draft genome of Yersinia pestis from victims of the Black DeathAbstract; Discussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: the perceived increased virulence of the disease during the Black Death may not have been due to bacterial phenotype ... may not be due to novel fixed point mutations detectable via the analytical approach described here

What this does not establish

A negative result at one resolution. The page’s "probably" carries the paper’s "may not", and the authors are careful to say what their method could and could not see.

Claim 36 · checked 24 September 2026 · AI-assisted audit

Claim: Whatever made it what it was involved the people, the climate, the fleas and the conditions they all lived in

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    A draft genome of Yersinia pestis from victims of the Black DeathDiscussion, final paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: molecular changes in pathogens are but one component of a constellation of factors contributing to changing infectious disease prevalence and severity, where genetics of the host population ... climate ... vector dynamics ... social conditions ... and synergistic interactions with concurrent diseases ... should be foremost

What this does not establish

A list of where the authors think the explanation lies, not a finding about which of them mattered.

Corrected

24 September 2026. Previously: “Whatever made it what it was involved the people, the rats, the climate or the fleas, and that is still being worked on.” Rats are not in the list Bos and others give. Theirs is host genetics, climate, vector dynamics, social conditions and other diseases, and the page now follows it.

Claim 37 · checked 24 September 2026 · AI-assisted audit

Claim: and that is still being worked on

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page saying the question is open. The cited discussion sets out what should be looked at rather than what has been settled.

  • Context

    A draft genome of Yersinia pestis from victims of the Black DeathDiscussion, final paragraph

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: molecular changes in pathogens are but one component of a constellation of factors contributing to changing infectious disease prevalence and severity

Claim 38 · checked 24 September 2026 · AI-assisted audit

What it implies

Claim: What it implies

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: A gene arrives, and a disease becomes the one history remembers.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The interlude compressing the passage above it. The gene is one of a sequence of changes, which the page says where it matters.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: our data suggest that Y. pestis did not fully adapt as a flea-borne mammalian pathogen until the beginning of the 1st millennium BC, which precipitated the historically recorded plagues

Claim 40 · checked 24 September 2026 · AI-assisted audit

What it did to those societies

Claim: What it did to those societies

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: The Bronze Age strains coincide with large population movements across the steppe and with turnover in the genetic ancestry of Europe.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Review of the field

    The source reads: It has recently been demonstrated by ancient genomics that the Bronze Age in Europe and Asia was characterized by large-scale population movements, admixture, and replacements

What this does not establish

The movements are established by other studies, which this one cites. What is new here is that seven infections fall in the same centuries.

Claim 42 · checked 24 September 2026 · AI-assisted audit

Claim: The 2015 authors call it plausible that outbreaks helped drive those movements, or were driven by them.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

  • Supports

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: In light of our findings, it is plausible that plague outbreaks could have facilitated–or have been facilitated by–these highly dynamic demographic events.

What this does not establish

Plausible is the authors’ own word, and they leave the direction open in both senses. The page keeps both.

Claim 43 · checked 24 September 2026 · AI-assisted audit

Claim: That is a coincidence in time, not a demonstration.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page refusing to read the overlap as cause. The paper runs no test of the association; it notes that its infections fall in the same centuries as movements documented elsewhere.

Claim 44 · checked 24 September 2026 · AI-assisted audit

Claim: The team that sequenced a five-thousand-year-old strain from a hunter-gatherer burial in Latvia reads it the other way: the few prehistoric cases found so far look to them like separate jumps from animals rather than an epidemic.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

  • Supports

    A 5,000-year-old hunter-gatherer already plagued by Yersinia pestisSummary

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: A 5,000-year-old Yersinia pestis genome (RV 2039) is reconstructed from a hunter-fisher-gatherer (5300-5050 cal BP) buried at Riņņukalns, Latvia ... Our data do not support the scenario of a prehistoric pneumonic plague pandemic

  • Supports

    A 5,000-year-old hunter-gatherer already plagued by Yersinia pestisSummary

    Cited · Link answered, 19 October 2026 · Abstract only, 24 September 2026 · Artefacts and sites · Measurement

    The source reads: The geographical and temporal distribution of the few prehistoric Y. pestis cases reported so far is more in agreement with single zoonotic events.

  • Context

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoDiscussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: The occurrence of plague in the Bronze Age Eurasian individuals we sampled (7 of 101) indicates that plague infections were common at least 3,000 years earlier than recorded historically.

What this does not establish

Only the published summary of Susat and others was readable here; the body of the paper was not. The disagreement is about how to read a scatter of cases, and both teams are working from very few of them.

Corrected

24 September 2026. Previously: “” The passage gave only the 2015 reading of what the Bronze Age infections mean. Later work reading the same scatter as separate spillovers from animals is a live disagreement, and the page now reports both sides.

Claim 45 · checked 24 September 2026 · AI-assisted audit

Claim: Seven positive individuals is a small sample from a vast region, and prevalence cannot be estimated from it.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page’s caution about what seven infections can support. The individuals were sampled for a study of ancient human genomes rather than for plague, from graves spread across Siberia, Estonia, Russia, Poland and Armenia.

  • Context

    Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years AgoResults; Discussion

    Cited · Link answered, 19 October 2026 · Read in full, 24 September 2026

    The source reads: we screened ... teeth of 101 Bronze Age individuals from Europe and Asia ... and found that seven individuals carried sequences resembling Y. pestis ... Although larger sample sizes are needed for confirmation

Other readings

The authors read seven of 101 as showing that plague infections were common. The page does not follow them that far.

Claim 46 · checked 24 September 2026 · AI-assisted audit

How much of history this can rewrite

Claim: How much of history this can rewrite

Kind
Framing. Signposting. It asserts nothing a source could check.

Claim: The same methods have settled arguments that descriptions could not.

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

One argument, settled by one kind of evidence. Should end the controversy is the authors’ phrase for their own result.

Claim 48 · checked 24 September 2026 · AI-assisted audit

Claim: Whether the plague of Justinian was plague at all was disputed for decades, until the bacterium was recovered from teeth in a sixth-century Bavarian cemetery.

Kind
Historical claim. A statement about the past that historical evidence can test.
Review
Source checked. The cited passage was read, and it says this.

What this does not establish

Aschheim is one cemetery in Bavaria, and not every tooth tested was positive. The result identifies the organism; it does not measure the pandemic.

Claim 49 · checked 24 September 2026 · AI-assisted audit

Claim: The limit is preservation.

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page naming what bounds the method, before saying what falls outside it.

Claim 50 · checked 24 September 2026 · AI-assisted audit

Claim: Diseases that do not enter the bloodstream, or that leave no DNA in bone, remain invisible

Kind
What scholars argue. A report of what specialists argue, or where they disagree.
Review
Partly checked. Only part of the source could be read. What was not read is listed.

What this does not establish

Read from the abstract only. It establishes that the method targets infections that reach the blood, which is the page’s point; it does not survey what other methods can reach.

Claim 51 · checked 24 September 2026 · AI-assisted audit

Claim: so the record that is being built is biased towards a particular kind of infection

Kind
This page’s reading. A judgement the page makes from the evidence. Others read it differently.
Review
A judgement, not a fact. Reviewed for whether it is fairly put and follows from the checked claims. No source can confirm it.

The page’s conclusion from the sentence before it: every study on this page recovered a blood-borne bacterium from teeth, so that is the kind of disease the growing record holds.

Claim 52 · checked 24 September 2026 · AI-assisted audit

What was read