The Great Transition

Well, I found the history of the medieval world I was looking for.  Bruce M. S. Campbell's central focus isn't Ghengis Khan and the Mongols, but since The Great Transition sets out to explain just why the Black Death happened when and where it did, he is forced to write a comprehensive ecological, political, and economic history of the age of the great Khan.  One component of this history is the westward spread of plague from its ancient native habitat in Qinghai and Tibet.  The unification of the Mongol empire is discussed in the book because it played a key facilitating role in that movement.  But of course, the full story is extremely complicated.

The fact that The Great Transition explores so many aspects of the full complexity of this era is exactly what makes the book itself great.  Campbell begins by reviewing a mountain of climatological evidence like tree ring widths, harvest records, solar radiation charts, etc ... to give us an overview of the way the climate shifted from the MCA (medieval climate anomaly) regime to the LIA (little ice age) regime right around the time of the first major plague outbreak in Northern Europe (1348).  This was a really major shift in temperature and precipitation patterns whose effect on humanity was compounded by the often observed volatility that accompanies a regime shift in dynamic systems.  One effect was increased rainfall in Qinghai, which resulted in increased grasslands, increased rodent populations, increased fleas, and increased spread of the plague bacterium within rodents.  A severe drought that followed this exceptionally rainy period seems to have been the trigger for desperate infected fleas to begin biting their next favorite host -- Mongolians.    In lesser hands, particularly in today's political environment, "the plague was caused by climate change" might have been the entire thesis.  But Campbell is that rare interdisciplinary thinker who resists reducing a complicated story to one that is neat, plausible, and wrong.  

He goes on to explore the many factors that went into the development of Northern Europe from a fallen Roman backwater to its 1100- 1300 CE efflorescece.  These range from the surprisingly positive effect of Christianity as a unifying force at this time, to the establishment of extensive trade fairs that added a significant market economy on top the existing feudal subsistence economy, to the integration of Europe into a global trading network that linked Genoa and Venice through the Middle East to the (at the time) more developed areas of China and India.  The composite picture he builds completely changed my image of late-medieval Europe.  In fact, he estimates that at its height in 1250, Venice was as rich per capita as anywhere in the world ever got before industrialization.  That is to say that it was pushing the technological frontier of trade specialization in a mostly agricultural economy.  His focus, however, is on the significantly less wealthy finge economy of England, simply because the English kept the best records.  With this data -- demographic, agricultural, economic, even the number of monasteries founded in 1200 -- he is able to go deeply into the details of what makes the European economy as a whole tick.  The complex of factors that led to a relatively wealthy and interconnected Europe are exactly the factors that made it vulnerable to the plague's spread.  

It's only from these heights that you can understand how Europe was brought low by the combination of climate, political, and economic changes that accelerated to a tipping point with the Black Death.  The weather got worse, causing harvest failures and undermining the economic viability of specialization and trade.  Cash rich european potentates made war on one another, which also increased transaction costs and reduced the radius of economic activity.  The Mamluks monopolized the traditional links between Europe and the East, which forced trade over the more expensive silk road routes and exposed Europe to the plague.  All these factors working in tandem are necessary to explain why the plague hit when and where it did and why it had such dramatic impact.  And Campbell doesn't shy away from exploring their individual complexity or their sometimes counterintuitive interactions.  

But he isn't done yet.  In the final chapter of the book he goes on to explore why it took Europe 150 years to recover from the plague, and how it's society had changed by the time economies and populations started growing again around 1500.  After the initial wave of plague that wiped out roughly 40% of the European population, there were a number of smaller waves that kept the population below replacement rate for generations.  While this reduction in population obviously led to a dramatic recession, it turns out that life for many of the survivors was actually much improved on average.  The reduction in labor force led to a doubling of the real wage rate over the next century or so, and since the plague destroys people but not farmland or equipment there was more capital to go around and a consequent halving of interest rates.  To top it off, Europe's silver mines (that had paid for much of the lopsided trade with Asia) were tapped out at this point, leading to widespread bullion famine and the deflationary spiral that happens when a market economy demonetizes.   All these factors locked Europe into a new post-plague equilibrium that prevented economic growth, trade, and populations from rebounding quickly.  These also account for some of the concerns that dominated Europe on the eve of the birth of colonialism.  Blocked from going Eastward, the continent reoriented towards the West, resulting in the great voyages of "discovery" to the West Indies and around the horn of Africa.  The significance of the fact that new stashes of gold lay in both these directions was not also lost on a bullion starved European economy.  And finally, there's nothing as great for incentivizing long-term productivity growth through technological investment as high real wage rates.  Let's hear it for the fight for $15, late medieval style!