A dna study has shed light on the world's earliest-known plague outbreak, with some reports suggesting it occurred around 5,500 years ago in siberia. The study's findings indicate that the plague was not spread by rats, but the actual carrier is not consistently reported across outlets, with one mentioning marmots as a possible transmitter. The discovery provides insight into the history of the plague, but details about the outbreak and its impact on human populations are still emerging.