The web of contingencies

History is really nothing more than one contingency after another.

This leaves fertile ground for the "what-ifs."  What if the Roman Emperor Titus -- who by all accounts was shaping up to be a pretty good leader -- had reigned for more than two years, instead of dying young in 81 C. E. and being succeeded by his cruel, paranoid brother Domitian?  What if King Edward V of England, one of the "Princes in the Tower," had lived, and the Tudor Dynasty never come to power?  What if Mehmed II lost the Battle of Constantinople in 1453, and the Byzantine Empire had survived?  What if the Spanish failed in their attempts to conquer the Aztecs, Incas, and Mayas?  What if the Confederacy won the American Civil War, the Cavaliers the English Civil War, the Republicans the Spanish Civil War, or the Nazis World War II?

Certainly some of these are more likely than others, but the fact remains that the threads of history are pretty fragile.  Speculating about what would have happened otherwise is the realm of fiction writers, and "alternative history" is a popular topic.  I remember reading one of the first stories to use that trope, R. A. Lafferty's brilliant (and hilarious) short story "Thus We Frustrate Charlemagne," when I was in college.  In Lafferty's tale an avatar is sent back in time by some scientists to make sure that Charlemagne is assassinated at Roncevalles in the year 778 (one of the nearest of historical near misses) instead of surviving, winning the day, and eventually becoming Holy Roman Emperor.

The problem, of course, is that when the avatar returns, it appears that nothing has changed, because in altering history it had altered the scientists' knowledge of what happened at the same time.  All it did was create a completely different set of contingencies leading to a different set of circumstances.  So they do it again, and again, changing other seemingly pivotal events in history -- each time with the same results.  Huge alterations, which none of the scientists are aware of, because their own memories shifted every time the past was changed.  It simply became what they always had known.

Ultimately, they conclude that nothing in the past made any difference, because changing past events never has any effect on the present!

In reality, though, we can speculate all we want about the what-ifs, but it will always remain in the realm of speculation.  As C. S. Lewis put it in Prince Caspian:

"You mean," said Lucy rather faintly, "that it would have turned out all right – somehow?  But how?  Please, Aslan!  Am I not to know?"

"To know what would have happened, child?" said Aslan.  "No.  Nobody is ever told that."

Maybe it's because I'm a fiction writer myself, but my mind was bouncing along amongst the what-ifs when I read some recent research about the settlement of Europe.  Back during the Neolithic Period, northwestern Europe had been settled by a culture called the Megalith Builders who had come there from the Balkans, and who were responsible for raising Stonehenge, Avebury, the Carnac Stones of Brittany, and the many other menhirs and stone rings scattered from Portugal to Denmark.  (Contrary to popular misconception, Stonehenge was not built by the "druids" or ancient Celts; when the Celts arrived in the British Isles, Stonehenge was already two thousand years old.)

The Carnac Megaliths of Brittany [Image licensed under the Creative Commons Snjeschok, Carnac megalith alignment 1, CC BY-SA 3.0]

The Megalith Builders thrived for a couple of millennia -- then, around five thousand years ago, the entire culture collapsed.  It was sudden, leading many historians and archaeologists to surmise that they'd been wiped out in a war.  There's a significant flaw in that theory, though.  The Megalith Builders were superseded by the Yamnaya, who came from the Pontic steppe and may have been the first speakers of an Indo-European language in Europe -- but there's at least a five hundred year gap (possibly more) between the sudden disappearance of the Megalith Builders and the first definitive archaeological traces of the Yamnaya.

So the collapse of the Megalith Builders didn't occur because the Yamnaya destroyed them; it seems like when the Yamnaya colonized northwestern Europe, they found the land already strangely depopulated.

A study this week in Nature has found strong evidence of what happened.  DNA evidence from gravesites indicates that of the bones dating from that four-hundred year period between 3,300 and 2,900 B.C.E., during which the Megalith Builders disappeared, one in six showed evidence they'd died of bubonic plague.

"It’s fairly consistent across all of Northern Europe, France and it’s in Sweden, even though there are some quite big differences in the archaeology, we still see the same pattern, they just disappear," said Frederik Seersholm of the University of Copenhagen, who led the study.  "All of a sudden, there’s no people getting buried (at these monuments) anymore.  And the people who were responsible for building these megaliths (are gone)...  These plague cases, they are dated to exactly the time frame where we know the Neolithic decline happened so this is very strong circumstantial evidence that the plague might have been involved in this population collapse."

So the plague seems to have had effects on Europe's history besides the devastating Black Death pandemics in the mid-fourteenth and mid-seventeenth centuries.  And this is where the what-ifs come in; what if the epidemic that struck down the Megalith Builders hadn't happened?  When the Yamnaya came in five centuries later, they would have found a thriving civilization that undoubtedly would have pushed back on their incursions.  And if the historical linguists are right, this would have stopped the progress of Indo-European speakers in their tracks.

What languages would we people of northern European descent now be speaking?

So that's today's ramble through history, alternative and otherwise.  And even if Aslan's right that no one is ever told what might have happened, that doesn't stop us from wondering and speculating how things would have gone if the web of contingencies was rearranged by a little bit.

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The law of whatever works

One common misconception about the evolutionary model and natural selection is that it always leads to greater fitness.

It's fostered by the way the subject is taught; that evolution always works by "survival of the fittest," so over time organisms always get bigger, stronger, faster, and smarter.  There's a kernel of truth there, of course; natural selection does favor the organisms that survive longer and have more offspring.  But there are a number of complicating factors that make this oversimplified impression far wide of the truth.

First, evolution -- in the sense of changes in gene frequencies in populations -- can happen for other reasons besides fitness-based natural selection.  One common example is sexual selection, when a characteristic having little to nothing to do with fitness is the basis for mate choice, such as bright color in the males of many bird species.  This has led to sexual dimorphism -- males and females have dramatically different external appearance, as the females choose ornately-adorned mates who then pass those genes on to their offspring.

Second, the selecting factors can change when the environment does.  What is an advantage today can be a disadvantage tomorrow.  This can lead to what's called an evolutionary misfire -- when some characteristic that was beneficial turns deadly as the conditions change.  A particularly interesting example of this is the way moths navigate.  Moths, like most insects, have compound eyes, hemispherical structures with multiple radially-oriented facets.  They find their way around at night by using distant light sources (such as stars and the Moon), keeping the light from those objects shining into one facet of the eye.  If the light source is distant, this allows the moth to fly in a straight line.  The problem is, moths evolved in a context where there were no nearby light sources at night; and if you try this orientation trick on a close-up light source, you end up flying in circles.

And this is why moths spiral around, and eventually get fried by, candles, lanterns, and streetlights.

Third, many -- probably most -- genes have multiple effects, a phenomenon called pleiotropy.  A single gene that can provide a benefit in one way can provide a serious disadvantage in another.  This is, in fact, why this topic comes up today; scientists at the University of Chicago showed that a gene -- ERAP2 -- that gave people in the fourteenth century a better shot at surviving the bubonic plague also predisposes them (and their descendants) to Crohn's disease.

The link, of course, is the immune system; Crohn's is an autoimmune disease, one where the body's immune system starts fighting against its own tissue, in this case the lining of the digestive tract.  The improvement in survival during the Black Death was significant -- an estimated forty percent increase in the chances of fighting off the disease -- so during the pandemic, the increase in risk for Crohn's was an acceptable tradeoff for near certain death from the plague.

Evolution is, truly, "the law of whatever works at the time."  It's not forward-looking; the forces of selection act on whatever genes the population has currently got, and the set of genes which is able to make more copies of itself is the one that gets passed on to the next generation.  This can happen because of reasons of fitness, but for many other causes including pure random chance (what is called genetic drift).

And because of this, the genetic hand we were dealt can sometimes have untoward consequences -- in a world where the bubonic plague has in most places been eradicated, a gene that had a beneficial effect now turns out to be a significant disadvantage.

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A commerce in death

My novella We All Fall Down is set during some of the most awful years humanity has ever lived through -- the middle of the fourteenth century, when by some estimates between a third and half of the people in Eurasia died of the bubonic plague, or as they called it, the "Black Death."

Back then, of course, no one knew what caused it.  Not only that the disease came from a microscopic organism, but that it was carried by fleas and spread by the rats that carried them.  The superstition of the time meant that people became desperate to find out why this catastrophe had occurred, and the blame was placed on everything from God's wrath to evil magic by witches, warlocks, and (unfortunately for them), the Jews.

It's natural enough to try to figure out ultimate causes, I suppose, even though they can be elusive.  I tried to express this in words of the narrator of We All Fall Down, the young, intelligent, inquisitive guardsman Nick Calladine, who has found himself entangled in a situation completely beyond his comprehension:

I asked Meg if she would be all right alone, and she said she would.  There were one or two other villagers who had survived the plague, and they were helping each other, and for now had enough to eat.  I wondered what would happen when winter came, but I suppose that their plight was no different from that of many in England.  Some would make it, some would not, and that was the way of things.  We are not given to understand much, we poor mortals.  The religious say that after we die we will understand everything, and see the reasons that are dark to us now, but I wonder.  From what I have seen, things simply happen because they happen, and there is no more pattern in the world than in the path a fluttering leaf takes on the wind.  To say so would be considered heresy, I suppose, but so it has always seemed to me.

The proximal cause of the Black Death -- rats, fleas, and the bacterium Yersinia pestis -- doesn't explain why the disease suddenly caught hold and exploded its way through the population.  One of the more plausible explanations I've heard is that climatic changes were the root cause; the Northern Hemisphere was at the time in the beginning of the "Little Ice Age," and the colder, harsher weather caused crop failure and a general shortage of food.  This not only weakened the famine-struck humans, but it drove rats indoors -- and into contact with people.

Seventeenth-century "plague panel" from Augsburg, Germany, hung on the doors of houses to act as a talisman to ward off illness [Image is in the Public Domain]

The reason all this dark stuff comes up is that a new study, by a team led by Maria Spyrou of the Eberhard Karls University of Tübingen and the Max Planck Institute, has added another piece to the puzzle.  Using a genetic analysis of bones from a cemetery in Kyrgyzstan, which lay beneath a stone whose inscription indicated they'd died of the plague, Spyrou et al. found that not only did the DNA from remnants of Y. pestis in the bones match those of European plague victims, it matched extant reservoirs of the bacteria in animals from the nearby Tian Shan Mountains.

The authors write:

The onset of the Black Death has been conventionally associated with outbreaks that occurred around the Black Sea region in 1346, eight years after the Kara-Djigach epidemic [that killed the people whose bones were analyzed in the study].  At present, the exact means through which Y. pestis reached western Eurasia are unknown, primarily due to large pre-existing uncertainties around the historical and ecological contexts of this process.  Previous research suggested that both warfare and/or trade networks were some of the main contributors in the spread of Y. pestis.  Yet, related studies have so far either focused on military expeditions that were arguably unrelated to initial outbreaks or others that occurred long before the mid-fourteenth century.  Moreover, even though preliminary analyses exist to support an involvement of Eurasian-wide trade routes in the spread of the disease, their systematic exploration has so far been conducted only for restricted areas of western Eurasia.  The placement of the Kara-Djigach settlement in proximity to trans-Asian networks, as well as the diverse toponymic evidence and artefacts identified at the site, lend support to scenarios implicating trade in Y. pestis dissemination.

So it looks like the traders using routes along the Silk Road, the main conduit for commerce between Europe and East Asia, may have brought along more than expensive goods for their unwitting customers.

Scary stuff.  I hasten to add that although Yersinia pestis is still endemic in wild animal populations, not only in remote places like Tian Shan but in Africa (there have been recent outbreaks in Madagascar and the Democratic Republic of Congo) and the southwestern United States/northern Mexico, it is now treatable with antibiotics if caught early enough.  So unlike the viral disease epidemics we're currently fighting, at least we have a weapon against this one once you've contracted it, and it's unlikely to wreak the havoc now that it did in the past.

At least we are no longer in the situation of horrified bewilderment that people like Nick Calladine were, as they watched their world shattering right before their eyes.  "My father was one of the first to take ill, in July, when the plague came, and he was dead the same day," Nick says.  "My sister sickened and died two days later, her throat swollen with the black marks that some have said are the devil’s handprints.  They were two of the first, but it didn’t end there.  In three weeks nearly the whole village of Ashbourne was dead, and I left alive to wonder at how quickly things change, and to think about the message in Father Jerome’s last sermon, that the plague was the hand of God striking down the wicked.  I wonder if he thought about his words as he lay dying himself at sundown of the following day."

Although we still don't have the entire causal sequence figured out, we've come a long way from attributing disease to God's wrath.  With Spyrou et al.'s new research, we've added another link to the chain -- identifying the origins of a disease that within ten years, had exploded out of its home in Central Asia to kill millions, and change the course of history forever.

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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.

The Black Death, aliens, and the role of chaos in history

Yesterday's post, about the alien origins of humanity, generated a nice round of "you think that's a crazy belief, wait till you see this one!" from my readers.  The best contender in this game of Wingnut One-Upmanship came from another student, who found out that not only did aliens produce our species, they've been trying to kill us ever since.

I guess it's understandable, really.  Our stewardship of the globe hasn't exactly been praiseworthy.  It's no wonder that our superpowerful alien cousins, who still presumably live on our original homeworld (with its clement temperatures, 30-hour rotational period, and "no geomagnetic storms or glaciers"), would have some second thoughts about sending us here.  So it turns out that they've repeatedly tried to get rid of us.

This conclusion comes from a stellar piece of research entitled "Did Aliens Create the 'Black Death' and Other Diseases During the Middle Ages?  (And Are They Still Creating Diseases Today?)," which not only would win an award for the longest article title ever, but is yet another example of a piece of journalism that should say, in its entirety, "NO."  Unfortunately, the author doesn't take that route.  We're told that the 14th century plague has to be extraterrestrial in origin:

A great many people throughout Europe and other plague-stricken regions of the world were reporting that outbreaks of the plague were caused by foul-smelling “mists” and bright lights were reported far more frequently and in many more locations than were rodent infestations. The plague years were, in fact, a period of heavy UFO activity.

Well, I hate to be unimaginative, but the foul smells during the Middle Ages don't really require UFOs to explain them.  There was a fairly appalling lack of sanitation, particularly in the big cities.  Apparently just the amount of human waste lying around in heavily populated areas was enough to create a smell that would blow your hair back -- even 19th century London was a frightful-smelling place, according to Steven Johnson's wonderful book The Ghost Map (which chronicles the cholera epidemic of the 1850s, and how it led to the creation of an efficient city-wide sewer system).  And the fact that rodents weren't "reported frequently" is pretty certainly because of their ubiquity, not because they were absent.

But of course, it's not just the stinky mist and bright lights that are brought out as evidence:

A second phenomenon was sometimes reported: the appearance of frightening human-like figures dressed in black. Those figures were often seen on the outskirts of a town or village and their presence would signal the outbreak of an epidemic almost immediately. It appears that the “scythes” may have been long instruments designed to spray poison or germ-laden gas. Strange men dressed in black, “demons’ and other terrifying figures were observed in other European communities. The frightening creatures were often observed carrying long “brooms,” “scythes,” or “swords” that were used to “sweep” or “knock” on the doors of people’s homes. The inhabitants of those homes fell ill with plague afterwards. It is from these reports that people created the popular image of “Death” as a skeleton or demon carrying a scythe. In looking at this haunting image of death, we may, in fact, be staring into the face of the UFO.”

Right.  Because we're not talking about a superstitious, credulous bunch of people here.  They can't possibly have made this up to explain a terrifying event that they didn't have the science to understand.

 Maybe it wasn't rats or aliens.  Maybe it was the "saaaalmon mooouuussse."

But then we find out that it wasn't all aliens who were impersonating Death; it was only the crazy homicidal aliens who were responsible:

This Awareness indicates that what in Medieval times were termed demons, and what many of the Christian faith considered to be demons, are in fact what entities refer today to as extraterrestrial aliens. The Greys from Zeta Reticuli today are not precisely the same invaders as those of the Medieval times. The Medieval aliens were both Reptoid and also of the Grey community that now is underground and known as the Deros. The Deros underground are demented forms of Zeta Greys, which have been here for many thousands of years, living underground to avoid sunlight and to avoid communication with humans except on those occasions where they seek to make contact for one reason or another.

Oh.  Okay.  Because that makes sense.

You know, I think that the problem here is that people are uncomfortable with the chaotic, random nature of much of life, especially the bad parts.  If something bad happens, the immediate impulse is to look for someone, or something, to blame.  This explains so much woo-woo thinking, doesn't it?  Without even trying hard, I found three examples that were linked on Reddit in the last two days -- an article on the website of the Institute for Natural Healing that attributes all cancer to eating meat, a claim that the government is covering up how dangerous vaccines are, and an allegation that WiFi in schools is causing headaches in children. 

Somehow, we just can't accept that people get sick, sometimes for no obvious reason.  It's not enough to celebrate the astonishing advances in medical science over the last hundred years, that have generated new records in the healthy human life span -- because, unfortunately, they haven't eliminated all disease and suffering.  The fact that we still get sick, we still grow old and die, must mean that there is some insidious plan behind it all.

It can't just be that we live in a world that's kind of a rough place, a world where bad things happen sometimes.  Not even in the case of the Black Death, where we (1) have identified the bacterium that causes it, (2) know the vector that transmitted it, (3) have evidence from medical records of the time that the symptoms are consistent with subsequent outbreaks, and even (4) have tissue samples (bones) that show evidence of Yersinia pestis infection.  No, that's not enough.  It has to be the evil demented aliens causing it all.

Anyhow, however understandable it is to want there to be some kind of overarching reason why stuff happens, rationality forces us to concede the role that chaos has in human history.  No extraterrestrial epidemics necessary.

And in case any of you were considering trying to one-up this story, I have to request, with all due respect: if you know of anything loonier than this claim, you probably shouldn't tell me about it.  I've done enough facepalms over this one to last me a while.