How the black rat colonized Europe in the Roman and Medieval periods

The black rat colonized Europe twice in the Roman and Medieval periods, according to new ancient DNA analysis.

The first ancient genetic study of the Rattus rattus, also known as the ship rat, was led by the University of York.

The researchers used ancient black rat remains found at archaeological sites in Europe and North Africa to piece together a new understanding of how rat populations dispersed following the ebbs and flows of human trade, urbanism, and empires.

Disappearance.

The study shows that the black rat colonized Europe at least twice, once with the Roman expansion and then again in the Medieval period, matching up with archaeological evidence for a decline or even disappearance of rats after the fall of the Roman Empire.

The break-up of the Roman economic system is what the authors of the study say. The Medieval period saw a new wave of black rats.

The black rat, along with the house mouse and brown rat, have become globally distributed as a result of their ability to live around humans by taking advantage of food and transportation.

Competition.

Competition with the newly arrived brown rat is thought to have caused the decline of the black rat population in Europe.

The Department of Archaeology has known for a long time that the spread of rats is linked to human events and that Roman expansion brought them to Europe.

One remarkable result of our study is how much of a single event this seems to have been: all of our Roman rat bones from England to Serbia form a single group in genetic terms.

When rats reappear in the Medieval period, we see a completely different genetic signature, but again all of our samples from England to Hungary to Finland all group together. We couldn't have hoped for clearer evidence of colonization.

A signature.

The history of black rats in Europe has been obscured by the modern dominance of brown rats. Genetic signatures of ancient black rats show how closely black rat and human population dynamics mirror each other.

He Yu, co-author from the Max Planck Institute, says that the study shows how the genetic background of human commensal species, like the black rat, could reflect historical or economic events. More attention should be paid to the neglected small animals.

It's called Flourish.

The researchers say that the study could be used to provide information about human movement.

The results show how the black rat, an animal which thrives around human settlements, can act as an ideal proxy for human historical processes.

The research, published in Nature Communications, was a collaboration between York and partners including Oxford.

More information: He Yu et al, Palaeogenomic analysis of black rat (Rattus rattus) reveals multiple European introductions associated with human economic history, Nature Communications (2022). DOI: 10.1038/s41467-022-30009-z Journal information: Nature Communications Citation: How the black rat colonized Europe in the Roman and Medieval periods (2022, May 3) retrieved 3 May 2022 from https://phys.org/news/2022-05-black-rat-colonized-europe-roman.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.