Do a little dance

One of the unfortunate things about having a skeptical approach is that sometimes, you have to admit you simply don't have an explanation.

I get that it's frustrating.  I used to run into this sometimes with students, and have conversations like the following:

Student: Do you think there's intelligent life elsewhere in the galaxy?

Me:  I don't know.

Student: But what do you think?

Me:  I don't think anything.  I simply don't know.  We have one example of a planet with intelligent life, and only vague guesses about how likely the conditions are that would select for intelligence.  It might be extremely common, or it might be extraordinarily rare.  We just don't know.

Student:  Doesn't that drive you crazy?

Yes, sometimes it does drive me crazy.  But if you're approaching the world scientifically, you better get used to it, because you're going to be spending a lot of time standing right up against what astrophysicist Neil deGrasse Tyson calls "the perimeter of our own ignorance."

And you don't have to go to the outer reaches of the galaxy to find phenomena that we've yet to explain -- ones for which, if you consider them honestly, you have to admit you may never have a good explanation.  The universe is big and weird and chaotic and complex, and frankly, we're lucky we've been able to explain as much of it as we have.

Which brings us to the Dancing Plague of 1518.

In July of the year 1518, in the town of Strasbourg, Alsace, a woman known to us only as Frau Troffea suddenly felt compelled to dance.  Unable to stop herself, she left her house and began to dance on the street, resisting all attempts to get her to stop.

Keep in mind that this was a highly superstitious time, when such behavior wouldn't have been considered comical; the early sixteenth century was the era of witch burnings and the heresy-hunters of the Inquisition.  To the onlookers of the time, Frau Troffea didn't seem funny, she looked as if she'd been possessed by a demon.

Worse, several other people joined her over the hours that followed.  During the next week, three dozen people were dancing; by mid-August, the numbers had risen to four hundred, and the illness -- whatever it was -- had spread to nearby towns.  At first, both the doctors and religious authorities suggested the victims be encouraged to dance themselves to exhaustion, to "dance free of it," and even hired musicians to keep them going.  But as the "dancing plague" spread through the countryside, panic ensued.  The powers-that-be reversed course, and forbade musicians from egging the dancers on.  The priests and bishops declared that the dancers were being punished by Saint Vitus, the patron saint of dancing, but what they'd done to merit that was never clear, as the dancers came from all walks of life.  Despite that, and probably driven by a desperation to do something, the religious authorities forced the dancers to wear shoes blessed with Holy Water, which had crosses embroidered on them, in the hopes that this might make the saint happy and stop the strange affliction.

Unsurprisingly, this had no effect whatsoever.

A depiction of some of the dancers in an engraving by Hendrik Hondius (1564) [Image is in the Public Domain]

By September, the whole thing began to die down.  Some contemporaneous sources say a few of the dancers danced themselves to death, but the number of fatalities (if any) are uncertain.  In the third week of September, the afflicted (now over their bad case of Boogie Fever) were sent to the shrine of Saint Vitus to receive absolution, and the whole episode ended.

So, what caused this bizarre outbreak?

If you're discounting the Demonic Possession Hypothesis and the Pissing Off Saint Vitus Hypothesis, there are two explanations that are most commonly proffered to account for the Dancing Plague, but both of them are not without their problems.

The first is that it was ergotism -- a condition caused by eating ergot-infected wheat and rye.  Ergot is a fungus that produces a chemical analog to LSD, and when consumed, it can cause bizarre hallucinations.  While this is a possibility, there are two main arguments against it.  First, an LSD trip doesn't last for weeks, and some of the people affected danced through most of July and August.  Second, severe ergotism -- consumption of large quantities of the fungus-infected grain -- triggers another effect of the chemical, which is vasoconstriction.  People with severe ergotism can have blood vessel constriction bad enough to cause gangrene in their extremities.  Considering how long the Dancing Plague went on, it's odd that if it was ergot, no one showed the other symptoms that usually come along with it.

The second is that it was an example of mass psychogenic illness.  This occurs when groups of people start exhibiting similar symptoms because of being part of a cohesive group and sharing similar biases and living conditions.  Put simply, it was superstition, hysteria, and the power of suggestion at work.  Examples of other illness thought to be caused by this phenomenon are the Tanganyika Laughter Epidemic of Tanzania and the "June Bug" incident in the southern United States, both of which (coincidentally) happened in 1962.  More controversially, some have explained Havana syndrome and Morgellons disease as psychogenic in origin -- but there are plenty of people who dispute both of those.

But as far as the Dancing Plague goes, there is one odd fact that argues against it being psychogenic in origin.  Almost every victim of the outbreak lived near water -- particularly along the Rhine and Moselle Rivers.  The farther away you were from the rivers, the less likely you were to be affected.  This gives the appearance of some sort of water-borne disease, but there's no known germ that has these effects.

Whatever caused the Dancing Plague -- and we still don't have an explanation that accounts for all of the known facts -- at least the authorities of the time didn't do what you might expect, which is to turn against the victims.  Considering the medieval tendency to see Satan hiding in every dark corner, it's kind of surprising they didn't.  There's no indication that, even after having spent a few weeks gettin' down, the victims were treated any differently afterward.

Maybe it was the trip to Saint Vitus's shrine that did the trick.

In any case, we really don't know what caused it.  Frustrating, but -- to come back around to my initial point -- given how weird and complicated the world is, that's gonna happen.  And as good skeptics, we have to be okay with it.  We can't explain everything, and even given all the facts at hand, there will still be times we have to shrug our shoulders and admit we don't know.

Even if it does drive us crazy.

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Tales of contagion

I have to admit to a morbid fascination with things that can kill you in nasty ways.

Tornadoes, hurricanes, earthquakes, mass extinctions from giant meteorite collisions -- and epidemics.  I remember first reading Daniel Defoe's A Journal of the Plague Year, about an outbreak of the Black Death in London in 1664 and 1665, when I was in college, and being simultaneously horrified and mesmerized at the scale of it.  An estimated 100,000 people died in two years -- a quarter of London's population.

But even that is dwarfed by two other epidemics.  First, there's the infamous outbreak of bubonic plague that started in 1347 and, by some estimates, killed one-third of the human population of the Earth -- something on the order of fifty million people.  The worst, though, was the "Spanish flu" epidemic of 1918 and 1919.  Odd that an event only a hundred years ago, and that killed an estimated 75 million people worldwide -- twice as many as World War I, which was happening at the same time -- is much less known.  Mention the Black Death, and almost everyone has an idea of what it is; mention the Spanish flu, and often all you get is a puzzled look.

Danse Macabre by Michael Wolgemut [image is in the Public Domain]

This all comes up because of a paper by Maria Spyrou et al. that appeared in Nature: Communications last week.  In it, the researchers describe looking for evidence of pathogens in the Bronze-Age burial sites -- and finding evidence that the bubonic plague has been with us for a long, long time.  The authors write:

The origin of Yersinia pestis and the early stages of its evolution are fundamental subjects of investigation given its high virulence and mortality that resulted from past pandemics.  Although the earliest evidence of Y. pestis infections in humans has been identified in Late Neolithic/Bronze Age Eurasia (LNBA 5000–3500y BP), these strains lack key genetic components required for flea adaptation, thus making their mode of transmission and disease presentation in humans unclear.  Here, we reconstruct ancient Y. pestis genomes from individuals associated with the Late Bronze Age period (~3800 BP) in the Samara region of modern-day Russia.  We show clear distinctions between our new strains and the LNBA lineage, and suggest that the full ability for flea-mediated transmission causing bubonic plague evolved more than 1000 years earlier than previously suggested.  Finally, we propose that several Y. pestis lineages were established during the Bronze Age, some of which persist to the present day.

Which is fascinating enough, but it bears mention that there are still a number of epidemics that scientists have no clear explanation for.  Here are three of the most puzzling:

1. "Sweating sickness."  In the late 15th and early 16th centuries, several waves of contagious illness swept through western Europe.  It killed fast -- starting with disorientation, fever, chills, aching joints, and finally progressing to delirium and copious sweating.  Most of the victims died within 36 hours of the onset.  It claimed a number of well-known victims, including Prince Arthur of England -- the son of King Henry VII, and brother of King Henry VIII.  Arthur's death at the age of fifteen put Henry in line for the throne, and set into motion events that would change the world -- such as the English Reformation and the founding of the Anglican Church.  Sweating sickness went as quickly as it started -- the last outbreak was in 1551, and it hasn't been seen since.  Scientists are still mystified as to the cause, but the speculation is it might have been a hantavirus, carried by mice.
2. The Dancing Plague of 1518.  In eastern France and western Germany, people were stricken by a disorder that caused shaking, mania, and... a desperation to dance.  People took to the streets, dancing desperately, many of them until they died of hunger, exposure, heat exhaustion, or stroke.  In Strasbourg alone, at the height of the plague, it was killing fifteen people a day.  It, like the sweating sickness, vanished as soon as it appeared, leaving everyone mystified as to its cause -- although some researchers suspect it might have been caused by ergot, a fungus that grows on wheat and rye and produces lysergic acid diethylamide -- LSD.
3. "Nodding syndrome."  This one is much more recent, having first emerged in the 1960s in Sudan.  It affects children, causing listlessness, stunting of growth (especially of the brain), and a peculiar symptom called a "nodding seizure," often triggered by eating or becoming cold.  The child's head bobs, and (s)he becomes unresponsive, the seizures lasting for up to ten or fifteen minutes.  It's progressive and fatal -- the usual duration being about three years.  To this day no one knows the cause, although some suspect it might be connected to parasitism by the roundworm Onchocercus volvulus, which is endemic in the area and also causes "river blindness."

So this combines my love of horrible things that can kill you with my love of unsolved mysteries.

Anyhow, I realize this is all kind of morbid, and I have no desire to ruin your mood.  After all, we live in an age where most of the worst diseases of antiquity have been vanished; even bubonic plague, if it's caught quickly, can be cured with antibiotics (and yes, there are still cases of it today).  Thankfully, we seem to have gotten rid of sweating sickness and the dancing plague, even if we've replaced them with Ebola fever and chikungunya and West Nile virus.  I'll still take what we've got today over life in the past, which was (accurately) described by Thomas Hobbes as "solitary, nasty, poor, brutish, and short."

Have a nice day.

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This week's recommended read is Wait, What? And Life's Other Essential Questions by James E. Ryan.  Ryan frames the whole of critical thinking in a fascinating way.  He says we can avoid most of the pitfalls in logic by asking five questions: "What?"  "I wonder..." "Couldn't we at least...?" "How can I help?" and "What truly matters?"  Along the way, he considers examples from history, politics, and science, and encourages you to think about the deep issues -- and not to take anything for granted.