Yeah, I know that European history – unless depicted as oppressive domination of people who were just minding their own business (right?) – is old and busted. And the usual answers to this sort of question focus on exciting and violent events: wars, revolutions and the like. Events that lend themselves to narrative storytelling, with beginnings, conflicts, crises, and resolutions. Throw in some fascinating personalities and you’ve got a hit show. We all love narratives, and of course we think that the things we love are also the most important.
Not always so, I say.
Assuming that they were not killed, robbed, raped or enslaved, the life of the average person was changed in no meaningful way by any of the Great Moments of History. By “average”, I mean the 90% of the population who were subsistence farmers from approximately 5000 BCE to 1850 CE.
They were poor and insecure before these conflicts and they were poor and insecure afterwards. They may have acquired new overlords who obliged them to obey commands in a new language or to call God by a different name, but their daily lives changed in no substantial way. Recognizable change occurred on the scale of centuries, not lifetimes.
Until about 1850, when Europeans invented the megacity.
Large cities are where change and innovation occur. Successful ones do this by bringing together people who have different knowledge and skill sets. Although we like to celebrate great scientists and inventors, the reality is that sustained change and innovation requires piecing together many small insights and improvements. Even a towering genius like Isaac Newton (not a man given to modesty) had to admit that if he saw further than others it was because he stood on their shoulders. Cities provide a sufficiency of shoulders for geniuses to stand upon. They allow progress to be continuous and cumulative, rather than spasmodic and episodic.
Cities provide the density of interactions necessary for the growth of wealth and knowledge. Measured as GDP and patent filings, wealth and knowledge increase exponentially as a function of human interactions [1] . It’s this exponential increase that allowed humans to break out of Malthus’ Trap, and increase wealth faster than population – something that had never before happened in human history.
The end of the poverty trap is by far the biggest event in human history, and it started in Europe. That’s a much bigger deal than all the battles in all of history put together.
TL;DR
The graph below shows the sizes of the world’s largest cities over the last 2000 years. European and North American cities are colored red.
Data are from one of the sources (Tertius Chandler) on this Wikipedia page. Other sources give different numbers, but the shape of the graph would not change.
For the first 1800 years of the Common Era, the largest cities in the world ranged in size in a band from 100K to 1M inhabitants, and showed no trend toward getting larger. This despite the fact that world population tripled (from 200M to 600M) over the same period. And European cities were rarely among the world’s largest. Looking at this as a biologist, and looking at cities as though they were organisms, I’d say some extrinsic factor limited their size.
So what was holding back city size? Most likely, infectious disease. Even in 1900, when most cities had clean water systems and public health departments that promoted vaccination, infectious diseases were the leading cause of death.
It turns out that the same equations which describe the spread of ideas in cities also describe the spread of disease. Cities promote innovation but they also promote disease. And diseases – particularly ones like tuberculosis that victimize prime-age adults – disrupt the virtuous cycle of innovation. Plagues and tech incubators are not at all compatible.
Infection control can’t be the whole answer of course. The phenomenon of city growth and its relation to innovation is far too complex for that. But I think it is fair to say that infectious disease control is a necessary condition for the formation and, especially, sustainability of large cities. Without it, we would have to disperse out into the country, just as the wealthy did periodically during plague times. Or just get sick and die. Either way, wealth creation and innovation grind to a halt, and we all go back to being poor and ignorant.
Footnotes
[1] Urban characteristics attributable to density-driven tie formation