section_path: 14th-century plague/Causes/DNA evidence
section_name: DNA evidence
paragraph_text: DNA evidence
  
  Definitive confirmation of the role of Y. pestis arrived in 2010 with a publication in PLOS Pathogens by Haensch et al. They assessed the presence of DNA / RNA with polymerase chain reaction (PCR) techniques for Y. pestis from the tooth sockets in human skeletons from mass graves in northern, central and southern Europe that were associated archaeologically with the Black Death and subsequent resurgences. The authors concluded that this new research, together with prior analyses from the south of France and Germany, "ends the debate about the cause of the Black Death, and unambiguously demonstrates that Y. pestis was the causative agent of the epidemic plague that devastated Europe during the Middle Ages". In 2011 these results were further confirmed with genetic evidence derived from Black Death victims in the East Smithfield burial site in England. Schuenemann et al. concluded in 2011 "that the Black Death in medieval Europe was caused by a variant of Y. pestis that may no longer exist".
  
  Later in 2011, Bos et al. reported in Nature the first draft genome of Y. pestis from plague victims from the same East Smithfield cemetery and indicated that the strain that caused the Black Death is ancestral to most modern strains of Y. pestis.
  
  Later genomic papers have further confirmed the phylogenetic placement of the Y. pestis strain responsible for the Black Death as both the ancestor of later plague epidemics—including the third plague pandemic —and the descendant of the strain responsible for the Plague of Justinian. In addition, plague genomes from prehistory have been recovered.
  
  DNA taken from 25 skeletons from 14th-century London showed that plague is a strain of Y. pestis almost identical to that which hit Madagascar in 2013. Further DNA evidence also proves the role of Y. pestis and traces the source to the Tian Shan mountains in Kyrgyzstan.