How the black rat colonized Europe in the Roman and Medieval periods


Date:
May 3, 2022
Source:
University of York
Summary:
New ancient DNA analysis has shed light on how the black rat,
blamed for spreading Black Death, dispersed across Europe --
revealing that the rodent colonized the continent on two occasions
in the Roman and Medieval periods. By analyzing DNA from ancient
black rat remains found at archaeological sites spanning the 1st
to the 17th centuries in Europe and North Africa, researchers have
pieced together a new understanding of how rat populations dispersed
following the ebbs and flows of human trade, urbanism, and empires.



FULL STORY ==========================================================================
New ancient DNA analysis has shed light on how the black rat, blamed
for spreading Black Death, dispersed across Europe -- revealing that
the rodent colonised the continent on two occasions in the Roman and
Medieval periods.


==========================================================================
The study -- led by the University of York along with the University
of Oxford and the Max Planck Institute -- is the first ancient genetic
study of the species (Rattus rattus), often known as the ship rat.

By analysing DNA from ancient black rat remains found at archaeological
sites spanning the 1st to the 17th centuries in Europe and North
Africa, the researchers have pieced together a new understanding of
how rat populations dispersed following the ebbs and flows of human trade,urbanism, and empires.

The study shows that the black rat colonised Europe at least twice,
once with the Roman expansion and then again in the Medieval period
-- matching up with archaeological evidence for a decline or even
disappearance of rats after the fall of the Roman Empire.

The authors of the study say this was likely related to the break-up of
the Roman economic system, though climatic change and the 6th Century Justinianic Plague may have played a role too. When towns and long-range
trade re-emerged in the Medieval period, so too did a new wave of
black rats.

The black rat is one of three rodent species, along with the house mouse
(Mus musculus) and brown rat (Rattus norvegicus), to have become globally distributed as a result of its ability to live around humans by taking advantage of food and transportation.



========================================================================== Black rats were widespread across Europe until at least the 18th century, before their population declined, most likely as a result of competition
with the newly arrived brown rat (Rattus norvegicus), the now dominant
rat species in temperate Europe.

Dr David Orton from the Department of Archaeology said: "We've long known
that the spread of rats is linked to human events, and we suspected that
Roman expansion brought them north into Europe.

"But one remarkable result of our study is quite how much of a single
event this seems to have been: all of our Roman rat bones from England
to Serbia form a single group in genetic terms." "When rats reappear
in the Medieval period we see a completely different genetic signature
-- but again all of our samples from England to Hungary to Finland
all group together. We couldn't have hoped for clearer evidence of
repeated colonisation of Europe." Alex Jamieson, co-author at the
University of Oxford, said "The modern dominance of brown rats has
obscured the fascinating history of black rats in Europe. Generating
genetic signatures of these ancient black rats reveals how closely
black rat and human population dynamics mirror each other." He Yu,
co-author from the Max Planck Institute, said "This study is a great
showcase of how the genetic background of human commensal species,
like the black rat, could reflect historical or economic events. And
more attention should be paid to these often neglected small animals." Researchers said that the study could also be used to provide information
about human movement across continents.

"Our results show how human-commensal species like the black rat, animals
which flourish around human settlements, can act as ideal proxies for
human historical processes," added Dr Orton.

The research was a collaboration between York and partners including
Oxford, the Max Planck Institute, and researchers in over 20 countries.


========================================================================== Story Source: Materials provided by University_of_York. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. He Yu, Alexandra Jamieson, Ardern Hulme-Beaman, Chris J. Conroy,
Becky
Knight, Camilla Speller, Hiba Al-Jarah, Heidi Eager, Alexandra
Trinks, Gamini Adikari, Henriette Baron, Beate Bo"hlendorf-Arslan,
Wijerathne Bohingamuwa, Alison Crowther, Thomas Cucchi, Kinie Esser,
Jeffrey Fleisher, Louisa Gidney, Elena Gladilina, Pavel Gol'din,
Steven M.

Goodman, Sheila Hamilton-Dyer, Richard Helm, Jesse C. Hillman, Nabil
Kallala, Hanna Kivikero, Zso'fia E. Kova'cs, Gu"nther Karl Kunst,
Rene' Kysely', Anna Linderholm, Bouthéina Maraoui-Telmini,
Nemanja Marković, Arturo Morales-Mun~iz, Mariana Nabais,
Terry O'Connor, Tarek Oueslati, Ere'ndira M. Quintana Morales,
Kerstin Pasda, Jude Perera, Nimal Perera, Silvia Radbauer, Joan
Ramon, Eve Rannama"e, Joan Sanmarti' Grego, Edward Treasure, Silvia
Valenzuela-Lamas, Inge van der Jagt, Wim Van Neer, Jean-Denis Vigne,
Thomas Walker, Stephanie Wynne- Jones, Jo/rn Zeiler, Keith Dobney,
Nicole Boivin, Jeremy B. Searle, Ben Krause-Kyora, Johannes Krause,
Greger Larson, David Orton. Palaeogenomic analysis of black rat
(Rattus rattus) reveals multiple European introductions associated
with human economic history. Nature Communications, 2022; 13 (1)
DOI: 10.1038/s41467-022-30009-z ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/05/220503141339.htm

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