Scurrying Seafarers

Rats are found on every continent where people live. They are despised by some for spreading disease, devouring food, or simply for their appearance and behavior. On the other hand, they are also loved by many as pets and important for use by scientists as laboratory animals. Almost every major city has a rat control project. Take a walk through your local commercial district and you will likely find dozens of black boxes containing poison baits intended to kill rats. But how did rats spread so far? Where did modern western attitudes towards rats come from? Have these attitudes changed over time? And how did rats shape the face of global history? My recent research traces how human attitudes towards rats on board ships changed from the 1850s to the 1950s, and, in turn, how ships themselves were transformed by the presence of rats.

  The expression “like rats fleeing a sinking ship” comes from the long association between rats and ships, from at least the 1500s to the mid-1900s. European ships, bringing colonists to the foreign lands that they violently seized from Indigenous people, also brought black and brown rats – the two most common species. Ships proved an ideal habitat for rats: they offered plentiful food and water (meant for sailors or for trade) and had ample nesting spots in the dark and warm spaces below deck.

  Rats could be major pests on board: they devoured supplies, sprung leaks in water containers, and sometimes even tore apart sails to make nests or gnawed their way through the ship itself. In the 1800s, some sailors developed strategies for exterminating rats. Some strategies included submerging vessels to drown them, filling ship compartments  with poisonous gases (fumigation), or keeping pet cats and dogs to scare them off or to kill them. Other seafarers tamed them and kept them as pets, hunted them for fun on long and dreary voyages, or ate them in times of food shortages. Some even believed that rat-eating could ward off scurvy, a disease caused by poor nutrition. One sailor even claimed that rats kept a crew healthy by consuming waste that might otherwise rot and cause diseases.

  Even if some sailors thought rats improved the overall health of the ship, they often did not enjoy sharing their living spaces with them. Accounts of life on board, often written by wealthy travellers and ship officers who stayed in the best ship living spaces, make for skin-crawling and disgusting reading. Thomas Boteler, a Lieutenant on the HMS Barracouta in 1826, for example, wrote that rats nibbled away at sailors’ fingers, at times gnawing “the skin off for nearly a quarter of an inch square”. While these officials found the animals a terror, those below deck experienced much worse, particularly enslaved people. Chained in the lower decks, and without shoes, they would have been almost defenceless against the rats gnawing at them. Even animals brought on board specifically to control rats, such as cats and dogs, were not safe. Cats were sometimes killed and devoured by rats, while large rats could even terrorise dogs by biting their feet and heels. Rat control measures were often so ineffective that most sailors felt getting rid of them for good was impossible. Their presence simply had to be accepted and tolerated.

  Beginning in the 1890s, relationships with rats became even more hostile. In 1897 and 1898, black and brown rats (as well as their fleas) were blamed by Ogata Masanori, a Japanese scientist, and Paul-Louis Simond, a French doctor, for spreading one of the most dreaded diseases in global history: bubonic plague. Plague is highly fatal if untreated, and treatments at the time only sometimes worked. There were many theories for how plague spread. Some thought it was spread by grain, humans, or numerous other animals including pigs and cats. Others thought it arose from the soil. So the idea that it was spread by rats and fleas was initially controversial. Despite such controversy, governments around the world acted quickly to contain the movements of rats across the oceans. Under international health regulations, plague outbreaks could lead to the quarantine of goods and travellers. This caused disruptions in the flow of commerce, and often spoiled entire cargoes of produce.

  Rats on ships now became almost completely unacceptable. Between the 1890s and 1920s, new measures were rapidly developed to eliminate them. This involved preventing rats from climbing on board, and nesting in the hold. To keep rats from climbing the ship’s ropes or climbing off board and onto shore, disks or cones called “ratguards” were introduced. The idea was to place a barrier on the rope which a rat could not climb over. In theory, this would stop infected animals from circulating between cities. In practice, ratguards usually did not work. Studies conducted in India and South Africa revealed that rats could learn to climb over them. Additionally, politicians in Australia complained that they were often so improperly installed that “not only a rat, but a cow, could get ashore on the mooring ropes”. Despite this, ratguards remain in use in some ports to this day.

  To control shipboard rat populations, ratguards were typically paired with fumigation, which scholars Lukas Engelmann and Christos Lynteris have written about. Fumigating machines flooded ships with poisonous gases to kill rats, fleas, or dangerous microorganisms lurking inside. But in many cases rats learned to flee into the woodwork of the upper parts of the ship, where the gases did not reach.

  In 1924, two New York based experts, surgeon Samuel B. Grubbs and pharmacist Benjamin E. Holsendorf, proposed a new solution: the complete rat-proofing of vessels. Rat-proofing was a strategy of structural interventions on board. To prevent rats from travelling  between rooms in search of food and water, they placed screens over doors and windows. To stop the rats from finding nesting places, they located gaps between furniture and floor, secluded openings of ventilation shafts and spaces between decks, and blocked them with barriers the rats couldn’t gnaw through. 

Rat-proofing was highly effective and reduced the rat population to zero in initial experiments. This success, combined with financial support provided by some governments, such as the United States government, caused rat-proofing to be quickly adopted. In 1931, the United States Public Health Service reported that as many as 75% of the “better-class ships” (more modern, wealthier, or better-constructed ships) coming into New York from 47 companies and 14 nations had been rat-proofed. By the 1950s, so many ships had been rat-proofed that rat killing operations on board were often no longer necessary.

So, why should we care about the history of rats on board ships? Firstly, this case shows how we cannot think of global history as a purely human affair. Rats utilised ships – human technologies of migration, conquest, and trade – for their own reasons. This allowed them to spread to every continent on the globe. In the context of a deadly pandemic, their presence on board also sparked pest control innovations, through the invention of rat killing machines and ratguards. However, rats learned to avoid every obstacle until engineers completely transformed and redesigned ships to make them dangerous for the rats. The story of rats on ships also changed modern ideas of rats from tolerable annoyances to public health enemy number one. However, blaming rats for the spread of plague also conveniently deflected attention away from the roles played by other things like international commerce, colonial settlement, and warfare. It also  provided a way to rationalise continuing trade during a pandemic: kill the rats, and commerce can continue on.

Written By: Dr. Jules Skotnes-Brown

Academic Editor: Chemical Engineer

Non-Academic Editor: Fashion Designer

Original Paper

• Title: Scurrying seafarers: shipboard rats, plague, and the land/sea border

• Journal: Journal of Global History

• Date Published: 05 May 2022

Please remember that research is done by humans and is always changing. A discovery one day could be proven incorrect the next day. It is important to continue to stay informed and keep up with the latest research. We do our best to present current work in an objective and accurate way, but we know that we might make mistakes. If you feel something has been presented incorrectly or inappropriately, please contact us through our website.