Editing Black rat (section)

==Origin==
The black rat was present in prehistoric Europe and in the [[Levant]] during [[postglacial]] periods.<ref name=Rackham>{{cite journal |author=Rackham, J. |title=''Rattus rattus'': The introduction of the black rat into Britain |journal=Antiquity |volume=53 |issue=208 |year=1979 |pmid=11620121|pages=112–120 |doi=10.1017/s0003598x00042319|s2cid=46387899}}</ref> The black rat in the Mediterranean region differs genetically from its South Asian ancestor by having 38 instead of 42 chromosomes.<ref>{{cite journal |last1=Yosida |first1=T. H. |last2=Tsuchiya |first2=K. |last3=Moriwaki |first3=K. |title=Karyotypic differences of black rats, ''Rattus rattus'', collected in various localities of East and Southeast Asia and Oceania |journal=Chromosoma |date=1971 |volume=33 |issue=3 |pages=252–267 |doi=10.1007/BF00284943 |pmid=5088494 |s2cid=12454478}}</ref> Its closest relative is the [[Asian house rat]] (''R. tanezumi'') from Southeast Asia. The two diverged about 120,000 years ago in southwestern Asia. It is unclear how the rat made its way to Europe due to insufficient data, although a land route seems more likely based on the distribution of European haplogroup "A". The black rat spread throughout Europe with the [[Campaign history of the Roman military|Roman conquest]], but declined around the 6th century, possibly due to collapse of the Roman grain trade, climate cooling, or the [[Justinianic Plague]]. A genetically different rat population of haplogroup A replaced the Roman population in the medieval times in Europe.<ref>{{cite journal |last1=Yu |first1=He |last2=Jamieson |first2=Alexandra |last3=Hulme-Beaman |first3=A. |last4=Conroy |first4=C. J. |last5=Knight |first5=B. |last6=Speller |first6=C. |last7=Al-Jarah |first7=H. |last8=Eager |first8=H. |last9=Trinks |first9=A. |last10=Adikari |first10=G. |last11=Baron |first11=H. |last12=Böhlendorf-Arslan |first12=B. |last13=Bohingamuwa |first13=W. |last14=Crowther |first14=A. |last15=Cucchi |first15=T. |last16=Esser |first16=K.|last17=Fleisher |first17=J. |last18=Gidney |first18=L. |last19=Gladilina |first19=E. |last20=Gol’din |first20=Pavel |last21=Goodman |first21=S. M. |last22=Hamilton-Dyer |first22=S. |last23=Helm |first23=R. |last24=Hillman |first24=J. C. |last25=Kallala |first25=N. |last26=Kivikero |first26=H. |last27=Kovács |first27=Zsófia E. |last28=Kunst |first28=G. K. |last29=Kyselý |first29=R. |last30=Linderholm |first30=A. |last31=Maraoui-Telmini |first31=B. |last32=Marković |first32=N. |last33=Morales-Muñiz |first33=A. |last34=Nabais |first34=M. |last35=O’Connor |first35=T. |last36=Oueslati |first36=T. |last37=Quintana Morales |first37=E. M. |last38=Pasda |first38=K. |last39=Perera |first39=J. |last40=Perera |first40=Nimal |last41=Radbauer |first41=S. |last42=Ramon |first42=J. |last43=Rannamäe |first43=E. |last44=Sanmartí Grego |first44=J. |last45=Treasure |first45=E. |last46=Valenzuela-Lamas |first46=S. |last47=van der Jagt |first47=I. |last48=Van Neer |first48=W. |last49=Vigne |first49=J.-D. |last50=Walker |first50=T. |last51=Wynne-Jones |first51=S. |last52=Zeiler |first52=J. |last53=Dobney |first53=K. |last54=Boivin |first54=N. |last55=Searle |first55=J. B. |last56=Krause-Kyora |first56=B. |last57=Krause |first57=J. |last58=Larson |first58=G. |last59=Orton |first59=D. |title=Palaeogenomic analysis of black rat (''Rattus rattus'') reveals multiple European introductions associated with human economic history |journal=Nature Communications |date=2022 |volume=13 |issue=1 |page=2399 |doi=10.1038/s41467-022-30009-z|pmid=35504912 |pmc=9064997 |bibcode=2022NatCo..13.2399Y}}</ref>

It is a resilient [[Vector (epidemiology)|vector]] for many diseases because of its ability to hold so many infectious bacteria in its blood. It was formerly thought to have played a primary role in spreading bacteria contained in fleas on its body, such as the plague bacterium (''[[Yersinia pestis]]'') which is responsible for the [[Plague of Justinian]] and the [[Black Death]].<ref name=McCormick>{{cite journal |author=McCormick, M. |title=Rats, communications, and plague: Toward an ecological history |journal=Journal of Interdisciplinary History |volume=34 |issue=1 |year=2003 |doi=10.1162/002219503322645439 |pages=1–25 |s2cid=128567627 |url=http://dash.harvard.edu/bitstream/handle/1/3208221/McCormick_RatsPlague.pdf}}</ref> However, recent studies have called this theory into question and instead posit humans themselves as the vector, as the movements of the epidemics and the black rat populations do not show historical or geographical correspondence.<ref> url=https://www.history.com/news/rats-didnt-spread-the-black-death-it-was-humans</ref><ref> {{Cite news |date=2018-01-15 |title=Black Death 'spread by humans not rats' |language=en-GB |work=BBC News |url=https://www.bbc.com/news/science-environment-42690577 |access-date=2023-03-06}}</ref> A study published in 2015 indicates that other Asiatic rodents served as plague reservoirs, from which infections spread as far west as Europe via trade routes, both overland and maritime. Although the black rat was certainly a plague vector in European ports, the spread of the plague beyond areas colonized by rats suggests that the plague was also circulated by humans after reaching Europe.<ref>{{cite journal |journal=Proceedings of the National Academy of Sciences of the United States of America |date=2015 |last1=Schmid, B.V. |last2=Büntgen, U. |last3=Easterday, W.R. |last4=Ginzler, C. |last5=Walløe, L.| last6=Bramanti, B. |last7=Stenseth, N.C. |title=Climate-driven introduction of the Black Death and successive plague reintroductions into Europe |doi=10.1073/pnas.1412887112 |pmid=25713390 |volume=112 |issue=10 |pages=3020–3025 |pmc=4364181 |bibcode=2015PNAS..112.3020S|doi-access=free}}</ref>