Why author James Mackinnon says our perception of rats and their role in the Black Death is wrong
/Dom Robazza loves rats.
The 27-year-old Brisbane veterinarian nurse has had 12 pet rats over the last six years and says "they're like tiny puppies".
She says the rats she keeps — also known as "fancy rats" — are easy to train, very smart and low maintenance.
Plus, she says, "rats are cute".
While Robazza adores her pets, the story of rats and humans is complex.
Certain rat species are considered essential in some native ecosystems, but others are seen as invasive and harmful to the environment. Rats are also viewed by many as disease carriers.
But their negative reputation may not be entirely deserved.
What caused the Black Death?
In the 14th century, the bubonic plague, also known as the Black Death, spread throughout Europe, killing an estimated 25 million people between 1347 and 1352.
The cause of the plague is often attributed to fleas infected with Yersinia pestis — the bacterium that causes the bubonic plague — which spread via the black rat.
"Of course, the Black Death is the origin story for a lot of our loathing [of] rats that has continued to today," journalist and author James Mackinnon, who has written about rats, tells ABC RN's Counterpoint.
But he argues there are problems with blaming rats for the Black Death.
Mackinnon says, for example, there isn't "a lot of evidence, or in some cases, no evidence whatsoever, that there were large populations of black rats … in Europe, north of the Mediterranean".
In 1970, the retired bacteriologist JFD Shrewsbury argued that there had never been enough rats in the UK to explain the spread of the bubonic plague, for example.
Mackinnon says an emerging alternative is the human ectoparasite theory.
According to that theory, it "wasn't fleas jumping off the rats and biting us that was causing the bubonic plague to spread", Mackinnon says.
Instead it was "our own unsanitary habits in that era, and our own tendency as societies to push our poor and marginalised into unclean housing, squalid housing".
"I wouldn't say that [the theory is] uncontested. There's certainly usual scientific process still at work here," Mackinnon adds.
"But there are now multiple threads of scientific pursuit, from genetics to history to archaeology, that are all indicating the same thing, which is that there most likely weren't large populations of rats in Europe at that time."
Smart, playful animal
Mackinnon says that while it's possible for rats to spread disease, that "doesn't mean that every rat that you encounter is going to be carrying disease".
He points to a 2022 study where researchers tested 96 brown rats in Vienna for specific viruses "of zoonotic importance" to the species. The study found that none of the tested rats were actively infected by these viruses.
Mackinnon argues that not only is the rat's disease-carrying reputation potentially undeserved, it also overshadows rats' intelligent nature.
One example Mackinnon discovered in his research is that rats are smart enough to play hide-and-seek.
In 2019 German scientists, attempting to study the playful behaviour in rats, found that five of the rats studied were able to understand and engage in the game.
"It turned out the rats could learn both of those roles very efficiently, but maybe more importantly, they really enjoyed the game. They were really engaged with it," Mackinnon says.
Mackinnon says that scientists rewarded rats during the experiment by tickling them.
"In this case, their only motivation for joining in the game was that they would get tickled when they were found, or when they found their captor," he says.
"So they were motivated not by profit in a rat sense, but simply by the desire to play."
Potential to help
Studies have also shown that some species of rats can have a positive impact on the environment or on the humans living alongside them.
In 2019, for example, it was discovered that Australian water rats had found a way to hunt and safely eat cane toads, an invasive species linked to the extinction of native animals.
African pouched rats have also been trained to sniff out landmines in countries like Cambodia, Mozambique and Azerbaijan.
This same species is also being tested to determine if it can detect tuberculosis and locate trapped disaster survivors.
James Cook University's Tasmin Rymer says rodents, including rats, have great potential to help other animals.
In 2019, Dr Rymer began researching whether native rats could be used to improve the chances of other animals being successfully introduced to new environments.
Dr Rymer says rodents are particularly adaptive and resilient to new and extreme environments. This makes them helpful in understanding how other animals might adapt in rewilding efforts, for example.
"I think one of the big things about rodents that a lot of people miss is that they are unique individuals," she says.
"A lot of our work … is looking at things like problem-solving, and individual levels of cognition and personality, to actually try and get a handle on just what level of variation we can be expecting in some populations."
Dr Rymer hopes this research will correct common misconceptions of native rats, and show how much there is to learn from rodents in general.
"One of the things I would really love to see with people is actually identifying that rodents are unique individuals, unique in and of themselves."
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