Historians and scientists have long debated whether the Justinianic Plague, which hit the Byzantine Empire in 541 AD before reaching Constantinople in 542 AD, was in fact caused by the same bacterium behind the Bubonic Plague.

A new study designed to lay the record straight, however, puts forth evidence that the two were in fact caused by Yersinia pestis.

“For a long time scholars from different disciplines have intensively discussed about the actual etiological agents of the past pandemics,” said Barbara Bramanti of the Palaeogenetics Group at the Institute of Anthropology at Johannes Gutenberg University Mainz.

The only way to come to a decisive, clear answer, scientists figured, was to conduct DNA analyses on skeletal remains of plague victims.

For this reason, researchers led by Michaela Harbeck from the Bavarian State Collection for Anthropology Palaeoanatomy in Munich collected the teeth of 19 individuals from 12 different burials from the 6th century.

Sure enough, analyses conducted in two separate aDNA laboratories independently confirmed that some of the humans buried in the cemetery where the samples were taken from had indeed contracted the notorious bacterium.

Furthermore, the authors write in the study, the discovery resolves the issue regarding the geographic origin of the Plague of Justinian.

“The phylogenetic position of our Y. Pestis samples from the first pandemic suggests all three plague pandemics were caused by Y. pestis strains originated out of Asia,” the authors write, referring to the pandemic of the 19th and 20th centuries in addition to the Justinianic and Black Plague.

However, as Bramanti explained in a press release, there are still questions that have yet to be resolved regarding the Justinianic Plague.

“It remains questionable whether at the time of the Byzantine Emperor Justinian only on strain or more were disseminated in Europe, as it was at the time of the Black Death,” she said.

Update: The study was led by researcher Michaela Harbeck, not Barbara Barmanti as previously stated.