New light on

the Black Death

Bruce M. S. CampbellProfessor of Medieval Economic

History,

The Queen’s University of Belfast

b.m.campbell@qub.ac.uk

The plague in TournaiThe plague in Tournai

London plague burialsLondon plague burials

Y. Pestis phylogenetic tree

Fundación Ramón Areces

Today, plague is a global disease with 1,000-2,000 cases a year reported to the World Health Organisation.Plague cases and deaths are both greatest in sub-Saharan Africa.

WORLD NEWS (August 2013):

15-year old herdsman dies of plague in

Krygyzstan.

WORLD NEWS (January 2015):

40 plague deaths in 2014 in

Madagascar!

WORLD NEWS (July 2014): Chinese city of Yumen sealed off after a man contracts plague from an infected marmot and dies.

Today, plague is a global disease with 1,000-2,000 cases a year reported to the World Health Organisation.Plague cases and deaths are both greatest in sub-Saharan Africa.

Fear of plague derives from history’s 3 great pandemics:AD 541: First Pandemic (Justinianic Plague) – devastated the Byzantine Empire.1346: Second Pandemic (Black Death) – spread throughout the Known World and killed 30%-40% of a European population of c.80 million (24-32m.).1855: Third Pandemic – broke out in Yunnan Province of China; spread worldwide; the first to be medically analysed and diagnosed.

The impact of the Black Death and its sequel plagues upon European populations was massive and long lasting:

Economic output also contracted almost everywhere, as plague killed both producers and consumers:

Decades

Indexed GDP per head

In terms of GDP per head, loss of numbers proved to be beneficial for England and Holland, a mixed blessing for Italy, and a significant setback for Spain:

In England the sudden scarcity of labour triggered the single greatest inflation in labourers’ daily wage rates on historical record.

In Siena work on the vast new nave being added

to the cathedral of Santa Maria Assunta was abandoned and

never resumed.

In Siena work on the vast new nave being added

to the cathedral of Santa Maria Assunta was abandoned and

never resumed.

In neighbouringFlorence, work on

Giotto’s new Campanile was

suspended at the second stage and only

resumed after an interval of 10 years.

Irish

English

Across Europe woodland regenerated as:

Construction activity almost ceased.

Farmland was abandoned.

Epidemiologically, demographically, environmentally, economically and culturally, the Black Death was a watershed historical event.

What disease was it?

The list of suspects has included: bubonic plague (Shrewsbury, 1971, and many others)

anthrax (Twigg, 1984)

a viral haemorrhagic fever (Scott & Duncan, 2001)

a now extinct disease (Cohn, 2002)

biological fallout from an extra- terrestrial impact in Jan. 1348 (Baill ie, 2006)

something else entirely . . . . .

PNASProceedings of the National Academy of Sciencesof the United States of America

November 2000, Volume 97, no. 23, pp. 12800-12803.

Claimed to have identified the DNA of Yersinia pestis (bubonic plague) in the dental pulp of medieval plague burials at Montpellier in southern France.

impreciseimprecise contaminatedcontaminated

unrepresentativeunrepresentative

The first forensic evidenc

e

October 7, 2010

STOP PRESSaDNA analysis proves the Black Death was vector-borne Yersinia Pestis after all!

Since 2010 confirmation that the Black confirmation that the Black Death was indeed bubonic plague, i .e.bubonic plague, i .e. Yersinia pestis , has come from aDNA analysis of dental remains from datable 14 th-century plague burials in 5 Western European countries:

1.1. France (France ( Saint Laurent-de-la-CabrerisseSaint Laurent-de-la-Cabrerisse) )

2.2. Italy (Italy ( Parma & VeniceParma & Venice) )

3.3. Southern Germany (Southern Germany ( AugsburgAugsburg) )

4.4. The Netherlands (The Netherlands ( Bergen op ZoomBergen op Zoom) )

5.5. England (England ( Hereford and East Smithfield, LondonHereford and East Smithfield, London).).

A Rapid Diagnostic Test has yielded A Rapid Diagnostic Test has yielded complementary results.complementary results.Crucially,Crucially, these aDNA results have been obtained in separate laboratories by independent teams of scientists.

Meanwhile, a 23-strong team of biologists & geneticists has reconstructed the Yersinia pestis phylogenetic tree:

Giovanna Morelli Giovanna Morelli and 22 others (2010), ‘Yersinia pestis genome sequencingsequencing identifies patterns of global phylogenetic diversity’, Nature Genetics 42 (12), 1140-43.

This has since been amplified and redefined in a key paper by Yujun Cui and 32 others to show where the Black Death genomes fit in:

‘PopulationPopulation structure of Y. pestis revealed by core genome SNP analysis’, PNAS 110 (2), 2013, 577-82.

Genetic reconstruction has yielded the following key conclusions:

1.Y. pestis evolves clonally; small mutations differentiate plague’s different branches (polytomies) and strains.2.Fresh polytomies are prone to emerge during major epizootics/panzootics.3.Almost all strains are capable of infecting and killing humans.4.There is nothing to suggest that the genomes responsible for the Black Death were more dangerous than any others.5.The 1st and 2nd Pandemics arose from different crossovers of the pathogen from animals to humans.

Genetic reconstruction has yielded the following key conclusions:6.The plague genome embodies its own evolutionary history and pattern of spread.7.Individual strains tend to be country-specific.8.Regions where plague has existed longest tend to exhibit the greatest genomic diversity and the presence of the earliest genotypes.

Genetic reconstruction has yielded the following key conclusions:6.The plague genome embodies its own evolutionary history and pattern of spread.7.Individual strains tend to be country-specific.8.Regions where plague has existed longest tend to exhibit the greatest genomic diversity and the presence of the earliest genotypes.

9.Geographically, the semi-arid Qinghai-Tibet Plateau of Western China appears to have been the ultimate origin of the Black Death.

The Qinghai-Tibet Plateau of Western China The Qinghai-Tibet Plateau of Western China

Genetic reconstruction has yielded the following key conclusions:6.The plague genome embodies its own evolutionary history and pattern of spread.7.Individual strains tend to be country-specific.8.Regions where plague has existed longest tend to exhibit the greatest genomic diversity and the presence of the earliest genotypes.

9.Geographically, the semi-arid Qinghai-Tibet Plateau of Western China appears to have been the ultimate origin of the Black Death.10.Temporally, the Black Death genome emerged during a biological ‘big bang’ shortly after 1268 (Cui and others, 2013) or 1282 (Bos and others, 2011).

c.1268/1282

Qinghai-Tibet is one Qinghai-Tibet is one of several regions of several regions where permanent where permanent (enzootic) reservoirs (enzootic) reservoirs of plague exist of plague exist among ground-among ground-burrowing and burrowing and hibernating sylvatic hibernating sylvatic rodents, in this case rodents, in this case great gerbils :great gerbils :

The plague The plague cycle:cycle:The The transformation of transformation of plague from an plague from an enzootic disease enzootic disease among among maintenance maintenance hosts of wild-hosts of wild-rodents to a fast-rodents to a fast-spreading and spreading and deadly human deadly human pandemic pandemic entailed at least entailed at least 4, and possibly 5, 4, and possibly 5, stages:stages:

The plague The plague cycle:cycle:

Stage 1 – Stage 1 – enzootic enzootic plagueplague

1

2

The plague The plague cycle:cycle:

Stage 2 – Stage 2 – epizootic epizootic plagueplague

3

The plague The plague cycle:cycle:

Stage 3 – Stage 3 – panzootic panzootic plagueplague

4

The plague The plague cycle:cycle:

Stage 4 – Stage 4 – Zoonotic Zoonotic plagueplague

Givry (Burgundy), 1348

Penrith (N England), 1597-9

5The plague The plague cycle:cycle:

Stage 5 – Stage 5 – Pandemic Pandemic plagueplague

The plague The plague cycle:cycle:Historically, Historically, climatic climatic conditions in Arid conditions in Arid Central Asia have Central Asia have exercised a exercised a powerful powerful influence upon influence upon the incidence of the incidence of plague, either plague, either lowering or lowering or raising the risks raising the risks of enzootic of enzootic plague becoming plague becoming amplified into amplified into epizootic plague epizootic plague etc.etc.

The Oslo plague team led by Nils Chr. Stenseth The Oslo plague team led by Nils Chr. Stenseth has investigated and established a link between has investigated and established a link between climate, gerbil populations, and outbreaks of climate, gerbil populations, and outbreaks of Yersinia pestis Yersinia pestis in the water-limited steppe in the water-limited steppe grasslands of southern Kazakhstan:grasslands of southern Kazakhstan:

Drought lowered the risks of plague outbreaks by Drought lowered the risks of plague outbreaks by depressing biomass output, food availability, and gerbil depressing biomass output, food availability, and gerbil populations and, at the same time, inhibiting flea activity.populations and, at the same time, inhibiting flea activity.

These were the conditions that prevailed in Arid Central These were the conditions that prevailed in Arid Central Asia throughout the Medieval Solar Maximum between Asia throughout the Medieval Solar Maximum between the end of the 1the end of the 1stst Pandemic in the the 8 Pandemic in the the 8thth century and century and start of the 2start of the 2ndnd Pandemic in the 14 Pandemic in the 14thth century. century.

Drought lowered the risks of plague outbreaks by Drought lowered the risks of plague outbreaks by depressing biomass output, food availability, and gerbil depressing biomass output, food availability, and gerbil populations and, at the same time, inhibiting flea activity.populations and, at the same time, inhibiting flea activity.

These were the conditions that prevailed in Arid Central These were the conditions that prevailed in Arid Central Asia throughout the Medieval Solar Maximum between Asia throughout the Medieval Solar Maximum between the end of the 1the end of the 1stst Pandemic in the the 8 Pandemic in the the 8thth century and century and start of the 2start of the 2ndnd Pandemic in the 14 Pandemic in the 14thth century. century.

Increasing aridityIncreasing aridity

Onset of pluvial conditions increased the risks of plague Onset of pluvial conditions increased the risks of plague outbreaks by raising biomass output, food availability, outbreaks by raising biomass output, food availability, and gerbil populations and, at the same time, stimulating and gerbil populations and, at the same time, stimulating flea activity.flea activity.

These were the conditions that prevailed in Arid Central These were the conditions that prevailed in Arid Central Asia following onset of the Wolf Solar Minimum and Asia following onset of the Wolf Solar Minimum and especially from the 14especially from the 14thth century as part of a global century as part of a global reorganization of atmospheric circulation. reorganization of atmospheric circulation.

Increasing humidity

Increasing humidity

Changes in atmospheric circulation across inner Eurasia

Changes in atmospheric circulation across inner Eurasia

Strong Westerlies

Weak Westerlies

Changes in atmospheric circulation across inner Eurasia

Parallel changes were taking place in the strength of the South Asian Monsoon:

Strong monsoon

Weakening monsoon

Mega drought

Weak Westerlies

Plague’s reactivation from an enzootic to an epizootic state sometime after 1268/1282 coincided with an episode of global climate reorganisation:

Dendrochronologies from Central Asia bring this episode into sharper focus:

Dendrochronologies from Central Asia bring this episode into sharper focus:

Dendrochronologies from Central Asia bring this episode into sharper focus:

Dendrochronologies from Central Asia bring this episode into sharper focus:

Ecological stress in Arid Central Asia, generated by increased climatic instability, appears to have ignited the epizootic that led to the Black Death.

W. EuropeW. EuropeChristakos, Olea & Christakos, Olea & Hwa-Lung (2007) Hwa-Lung (2007) c.c.1½-6 kms per day1½-6 kms per day

Qinghai / Tibet?Qinghai / Tibet?

Kipchak Khanate / Golden Horde

Kipchak Khanate / Golden Horde

Messina, SicilyMessina, Sicily

Issyk-Kul, Kirghizia

Issyk-Kul, Kirghizia

13461346

13471347

1338/91338/9

1290s?1290s?

c.40 yearsc.40 years2,000 kms2,000 kmsc.1 km per weekc.1 km per week

c.7 yearsc.7 years4,000 kms4,000 kmsc.c.1½ kms per day1½ kms per day

The speed of the Black Death’s spread implies that The speed of the Black Death’s spread implies that humans must in some way have been complicit in its humans must in some way have been complicit in its dissemination.dissemination.

The Catalan World Atlas, 1375:The Catalan World Atlas, 1375:

““ the intensification of over-land caravan the intensification of over-land caravan movement across Asia that reached its climax movement across Asia that reached its climax under the Mongol empires ... . . affected both under the Mongol empires ... . . affected both macro- and micro-parasitic patterns in far-macro- and micro-parasitic patterns in far-reaching ways” reaching ways”

The World-system of commerce c.1300 according to Janet Abu-Lughod, 1989.

Traders and travellers were material to the relentless westward Traders and travellers were material to the relentless westward spread of the pathogen, its vectors and hosts, until the Genoese spread of the pathogen, its vectors and hosts, until the Genoese port of Kaffa in the Crimea was reached in 1346.port of Kaffa in the Crimea was reached in 1346.

“In the same year [1346], God’s punishment struck the people in the eastern lands, in the town Ornach [on the estuary of the R. Don], and in Khastorokan, and in Sarai, and in Bezdeh, and in other towns in those lands; the mortality was great . . . . . so that they could not bury them” (Benedictow, 2004)

Gabriele de Mussis, Michele da Piazza, Nicephoros Gregoras, Emperor John VI & Ibn al-Wardi: Spring 1346: plague first surfaced in the lands of the Kipchak Khanate of the Golden Horde.

The Black Death - some fresh insights from recent research:

1. The Black Death WAS Yersinia pestis.

2. Its geographical origin was the semi-arid Qinghai-Tibet Plateau in Western China, where its maintenance hosts were wild gerbils and marmots.

3. Its biological re-activation from a dormant enzootic state to a more virulent epizootic state occurred during the closing decades of the 13th century.

4. This vital biological transformation took place under conditions of mounting ecological stress generated by the alternation of drought and pluvial events, as global patterns of atmospheric circulation de-stabilized and changed.

The Black Death - some fresh insights from recent research: 5. Traders and travellers were instrumental

in aiding and abetting plague’s westwardspread across the interior of Eurasia.

6. Genoese mariners performed the same function once plague reached the Black Sea coast and had crossed over and infected commensal rodents (i.e. black rats).

7. In Europe, poverty, over crowding, high levels of commercial activity, war, harvest failure and unusually humid weather conditions combined to ensure that the Black Death’s spread was rapid and its mortality heavy.

8. Further changes in plague’s hosts and vectors may have added momentum and reach to the disease’s spread.

The Black Death - some fresh insights from recent research:

9. The Black Death was the product of a unique conjuncture of biological, climatic and human developments.

The Black Death - some fresh insights from recent research: 10.The fate of medieval Europeans was

intimately bound up with environ-mental developments taking place 6,000 kilometres to the east, in the semi-arid and sparsely populated interior of Central Asia.

EL FINEL FIN