Black Rat - Origin of Rattus Rattus

Origin of Rattus Rattus

Rattus rattus bone remains that date back to the Norman Period have been discovered in Britain. Evidence also suggests that R. rattus existed in prehistoric Europe as well as Levant (eastern Europe) during post-glacial periods. The specific origin of the black rat is uncertain due to the rat's disappearance and reintroduction. Evidence such as DNA and bone fragments also suggests that rats did not originally come from Europe, but migrated from southeast Asia.

Rats are resilient vectors for many diseases because of their ability to hold so many infectious bacteria in their blood. Rats played a primary role in spreading bacteria, such as Yersinia pestis, which is responsible for the Justinianic plague and bubonic plague. According to epidemiological models, Yersinia pestis originated outside of Europe which indicates that Western and central Europe have never had any natural rodent plagues. The modern Roman rat arose from an ancestor that originated in Malaysia. The number of chromosomes these Malaysian rats and the Mediterranean black rats differ by four chromosomes. Therefore, it seems that speciation could have occurred when the rats colonized southwest India, which was a primary country where Romans obtained their spices. Because Rattus rattus is a passive traveler, they could have easily traveled to Europe during the trading between Rome and the southwestern Asian countries. Evidence also suggests that, in 321–331 BC, Egyptian birds were preying on Mediterranean rats, though this is not enough to prove that Egypt was the source of the rats.