Subscribe now for full access and no adverts
If you want to know how liveable a city is, you can ask the rats. The cosmopolitan rodents will know exactly how resource-rich and wasteful in nutrients their human co-habitants are. Like a warring old couple, ratkind and humankind may find themselves at odds, but one rarely persists for long without the other, and they will keep telling tales on each other, dead or alive. The last point is key – it reminds us how useful faunal facts can be in archaeology.
Some years ago, zooarchaeologist David Orton conceived an ingenious idea to explore the history of trade and urbanism in past societies through their links with rat populations. The way in which these rodents are associated with the ups and downs of trade and settlements of all shades, he reasoned, makes them a perfect agent to rat out the secrets of ancient cities. This idea became the root of the Rattus project, which is now gnawing away at our preconceptions about the urban past at the University of York.
The rodent’s tale
Rats have a successful history of colonising niches around cities and other human settlements in many parts of the world for at least 2,500 years. For about as long, they have also been reviled by their hosts as food pests and agents of disease. Since the Middle Ages, people have blamed them for perpetrating the 14th-century Black Death – though their precise role in transmitting the plague pandemic remains controversial.
Using rats to inform on urban conditions, past and present, is not a new idea. In the early 20th century, the Dane Emil Zuschlag published a book in French: Le Rat migratoire et sa destruction rationelle. This and other works by him led in turn to rat-extermination legislation being enforced in Denmark. In 1909, W R Boelter, inspired by Zuschlag, published The Rat Problem, a work in which he also drew extensively on evidence for the impact of rats in past societies – with plenty of emphasis on their role in urban contexts. In April 1910, R K Dadachanji delivered a paper entitled ‘The Rat Problem and the Ancients’ in the Anthropological Society of Bombay, India. Dadachanji had been influenced by these earlier works, and gave a broad overview of the rat and its consequences, including on past societies, with a scope stretching from the northern European and Classical Mediterranean worlds to the East.
Common to all three works is a willingness by the authors to employ evidence from past urban societies to underline the unsavoury sides of rats at a time when cities were becoming increasingly densely packed with human inhabitants, prompting proliferating populations of their rodent neighbours. Indeed, it was these perceptions of unpalatable past problems that presented one reason why the spotlight of public opinion became trained on these pests. Even so, we now know that the rats attracting the suspicion of early 20th-century city dwellers were of a different kind to those that initially colonised Europe.
The first species of rat to spread beyond its native ranges in southern and eastern Asia was the black rat (Rattus rattus), which had probably reached Europe by the Iron Age. Unlike the Chinese, who still associate rats with wisdom, wealth, and prosperity, the Romans did not have a long-standing familiarity with the creatures, and in fact did not even distinguish between mice and rats as members of a different genus. Numerous coins from the Roman Republic depict images featuring rodents, which some have interpreted as representations of rats. However, while numismatists have studied these scenes, there is no one firm interpretation of what such iconography means, or indeed whether it shows rats or mice. A full study of rodents on ancient Roman coins is still awaited, and would make for an exciting book. Even so, it seemingly illustrates that these creatures were not just associated with plagues in Classical antiquity. Considering rodents more generally, it is clear that they could hold other associations, ranging all of the way from religious symbolism (connected, for example, with the cult of Apollo) to a sought-after delicacy in the form of dormice that were fattened in jars in Roman houses.
Faunal finds bring home the point about the urban inclination of Roman rats. Black rat bones are ubiquitous in Roman cities. In 2023, Gabriel Zuchtriegel, the director of the archaeological park of Pompeii, announced some of the findings from a new excavation investigating a room where slaves were living in the Roman villa of Civita Giuliana. Three rodents were found in the room: two mice in an amphora and a rat in a jug placed under one of the beds. Both these finds and a new way of doing archaeology – at Pompeii and other places – that focuses much more on what Gabriel calls ‘micro-excavations’ are rapidly changing our view of daily life in antiquity. In this case, it sheds fresh light on the co-habitation of humans and rats, even if we do not yet have the full picture of just how voluntary this case of co-habitation was on the human side.
In the early Middle Ages, by contrast, when urban centres either dwindled or were extinguished across much of Europe, rats virtually disappeared from the archaeological record for centuries. When, a few years ago, we excavated one of the busiest and messiest of the Viking harbour towns – Ribe in Denmark – David Orton eagerly peered at the materials caught by the mesh of our sieving station, but not a single rat bone emerged. Perhaps the early trading emporia of the North Sea were scattered too thinly to invite a gnawer reared on Roman excess. Or, more tantalisingly, perhaps the alleged plague propagator had succumbed to the infamous 6th-century Justinianic plague: the bubonic pestilence that anticipated the Black Death.
New rat in town
Tellingly, the rat pack made a swinging return to small towns and big cities alike in the High Middle Ages. Compared to their Roman predecessors, though, this was virtually a new population, as Orton’s team revealed in 2022 in an ancient DNA study in Nature Communications. Black rats declined once again in the wake of the Black Death. When European cities revived substantially in the 18th century, the commensal rodent was a newcomer: the brown rat (Rattus norvegicus), which had arrived via a new migration from Asia.
In a recent paper published in the journal Science, Orton’s team have followed the evolutionary history of this incomer as both a wild species and a hanger-on living alongside humans. They found that the brown rat had adapted to human habitation in Asia at least 850 years ago. Its early arrival in Europe is still barely charted. The first securely dated archaeological specimen comes from a 1796 wreck found off Corsica, by which time we know that naturalists had already been aware of the newcomer for at least half a century.
Contemporaries speculated that this new rat had arrived in Britain and Ireland via Norway, or maybe Russia. Current indications are that it stowed away on boats arriving directly from south Asia, establishing itself courtesy of the surge in shipping that accompanied early colonial commerce. This is one of the many links that remains to be confirmed, as archaeologists and geneticists continue to explore the remains.
Even so, the outline that has appeared from all this research shows how, over millennia, the history of rats can indeed shed new light on that of people. It is not mere fancy that the bare bones of zooarchaeology can reveal trade and urbanism. Instead, there really is nothing like a rodent to rat on the deal.
Rubina Raja is Professor of Classical Archaeology and Art and director of the Centre for Urban Network Evolutions, Aarhus University, Denmark. Together with Søren, she is founding editor of the Journal of Urban Archaeology.
Søren M Sindbæk is Professor of Medieval Archaeology at Aarhus University, Denmark, and co-director of the Centre for Urban Network Evolutions.
