Victims of the Black Death in the 14th century, whose remains were discovered during excavations for London's new Crossrail railway line. Photo: Crossrail Ltd
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Gerbils and squirrels, not rats, may have been responsible for the Black Death

New research has found that rats alone can't have been responsible for Europe's medieval plague outbreaks - and giant Central Asian gerbils may have been an alternative accessory to the crime.

The political and cultural impact of the Black Death, which is usually seen as beginning in the period 1347-1353, on European life was immense. At least a hundred million people were killed (and possibly more than twice that by some estimates), reshaping the economy of feudalism and influencing the wars and politics that followed for at least the next four centuries, as plague outbreaks struck cities and villages over and over again. The bacteria responsible, Yersinia pestis, has long been believed to have originated in China, and to have been carried from east to west in fleas living on black rats that migrated with the merchants moving along the Silk Road, first by camel across central Asian steppes and deserts, and then across the Black Sea and Mediterranean by ship to major trading ports like Venice.

This distributional jigsaw may be missing some pieces, however - a new study by Norwegian and Swiss bioscientists and climatologists instead points the finger at some different rodents as bearing some of the responsibility for spreading plague: grey marmots, long-tailed squirrels, camels and Mongolian gerbils.

In the paper, published in the Proceedings of the National Academy of Sciences, the authors looked at 4,119 records of historical plague outbreaks across Europe, and cross-referenced them with 15 climate records derived from analysing tree rings within the same regions as the outbreaks. They were testing the hypothesis that the plague, once it arrived in Europe, dug itself in by living among rat populations (or "rat reservoirs" as the authors call them), which then experienced regular population swellings and shrinkings as the climate adjusted to become more or less rat-friendly over the centuries. They expected to see that plague outbreaks correlated neatly with warmer, drier summers, and that periods with fewer outbreaks were wetter and colder - yet it didn't quite work.

Most of the outbreaks in the records could be traced to other outbreaks nearby, but there were a select few - 16 in total, all in port cities like London, Lisbon and Hamburg - which had no connection with other outbreaks nearby, and where brand new imports of Y pestis via trading ships must have been responsible.

This, in itself, isn't too remarkable, but the researchers did notice a strong correlation between the climate records of east Asia and these 16 outlier European plague outbreaks. For each of them, certain climate conditions in east Asia would, 15 years later, be followed by a large outbreak. Something was linking the two sides of the Eurasian continent, and the researchers see a number of different rodents as responsible.

Consistently, a warming climate followed by a sudden cooling seemed to kickstart the transmission of plague bacteria across the Silk Road. The researchers theorise that warmer summer made it easier for fleas to find hosts to live and feed on - but the crash in temperature kills those same hosts, meaning fleas jump to new species, including humans. The model they propose has this happening over the first couple of years after the climate event; then, as those fleas move through the human population, they hitch onto humans on the edge of the Silk Road trading networks of central Asia.

From there, the plague moved slowly over a decade or so along trading routes, surviving in the large populations of rodents that live in those areas. Once the migration hit the eastern edge of the Black Sea, the journey was then sped up thanks to the speed of ships - within two or three more years, the plague will have successfully travelled from one side of the world to the other, to infect those living in European cities. "This association strongly suggests that the bacterium was continuously reimported into Europe during the second plague pandemic," writes lead author Boris Schmid of the University of Oslo, "and offers an alternative explanation to putative European rodent reservoirs for how the disease could have persisted in Europe for so long."

This doesn't get the black rat (Rattus rattus) off the hook - it's still the key vector for plague transmission once the bacteria arrived in Europe with each new wave. But it does mean that other members of the rodent family lose some of their ability to act all cute and innocent.

Ian Steadman is a staff science and technology writer at the New Statesman. He is on Twitter as @iansteadman.

EmpLemon/YouTube
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The art of the YouTube Poop

What are YouTube Poops and why do we need them now, more than ever?

“The world today doesn't make sense, so why should I paint pictures that do?”

So, allegedly, said Pablo Picasso in a shrewd attempt to justify his love of putting noses where noses don’t actually go. It is imperative that you now hold this profound quotation firmly in your mind whilst you watch this four minutes and 57 second long clip of Arthur – the cartoon aardvark – being tormented by squirrels.

What you have just seen is an example of the art form primarily known as “YouTube Poop” (YTP). Beginning in the early Noughties, this cultural movement is characterised by confusing and shocking edits of Saturday-morning cartoons, video games, and viral videos. Though the Tens have seen the genre decline in popularity, the YTP is, nonetheless, one of the defining innovations of our era.

Those in the Poop community don’t actually like being labelled as artists, as one Yale student found out when he attempted to define them as such on the University’s technology blog. Though they have been compared to Dadaism, YTPs are more vile, violent, and most importantly, nonsensical than most artworks, but this is precisely why they are an asset to our age. In a world where – sorry Pablo, you got nothing on us – absolutely zero things makes sense, it is time for the YTP to have a comeback.

Despite its seeming randomness, the world of YTP is not without its rules. “Poopisms” are the common techniques and tricks used in videos to ensure they qualify as a true Poop. They include “stutter loops” (the repetition of clips over and over), “staredowns” (freezing the frame on a particular facial expression), and the questionably-named “ear rape” (suddenly increasing the volume to shock the viewer). One of the most humorous techniques is “sentence mixing”: forcing characters to say new sentences by cutting and splicing things they have said.

There are also firm rules about what not to do. Panning across a clip without adding another Poopism at the same time is considered boring, whilst using your own voice to dub clips is seen as amateur. By far the biggest barrier that Poopers* face in creating their videos, however, is the law.

Despite what many eight-year-olds on YouTube think, declaring that something is a “parody” in the description of a video does not make it exempt from copyright laws. The video below – regarded by at least two commenters as “the best YouTube Poop” ever – is missing audio 20 minutes in, as the creator was hit by a copyright claim.

Yet even the iron fist of the law cannot truly stop Poopers, who are still going (relatively) strong after the first YTP was created in 2004. YouTube Poops now even have their own Wikipedia page, as well as a page on TV Tropes and a WikiHow guide on how to create them, and for good measure, avoid them.

YouTube Poops have therefore undoubtedly secured their place in history, and whilst you might wander into a comment section to declare “What have I just watched?”, remember that Pablo Picasso once said: “The purpose of art is washing the dust of daily life off our souls.” He almost definitely wasn’t talking about “You are a Sad Strange Little Man” by cartoonlover98, but still.

* The term “Poopists” was rejected by the community for being “too arty”.

 

Amelia Tait is a technology and digital culture writer at the New Statesman.