I've heard that medieval European cities were population sinks, but what about Classical cities? It seems that, for wealthy people at least, living in a city was a pretty good way to get by (even if plenty of Romans fled to rural villas whenever they could). But what about poor people (I'm also familiar with the evidence that in at least some areas poor rural people were evidently healthier/more able to feed themselves after the breakdown of Roman government institutions)?
What kind of agricultural, medical and structural (both social and in a material sense) changes occurred in the 1000 years of time between them that could have pushed average health up or down?
Modern scholar Guy Geltner snarks that it was writers in ancient Greece, not medieval Europe, that gave us the idea of the inherently disease-ridden city. Lat medieval medical practitioners, fighting a turf war over who could treat which conditions or dispense which medications, might have preferred a little more disease from time to time. And Richard le Rakiere, who was sitting innocently on his latrine one fine August day in 1326 when the rotted boards snapped under his weight and he splashed into the cesspit below, would probably have welcomed a city less concerned with sanitation.
Characteristics of cities have absolutely been implicated in the high mortality rates of the ancient circum-Mediterranean world as well as medieval. This is true of the basics (disease, famine, violence) and of factors embedded in contemporary culture. Alex Scobie, for example, stresses everything from the medical advice for sick people to seek healing at public baths (take a bunch of people with different diseases or with vulnerable health conditions and put them in the same place; what could go wrong) to the frequent collapse of overcrowded tenement housing.
It's also true that ancient and medieval cities alike took measures to try to deal with some of these problems. And the most striking thing is probably how similar a lot of the challenges and solutions of what we might call "public health" were: slum housing, open sewers, air pollution, sanitation workers, public latrines, and charity for the "deserving poor" whose ulterior motive was to make the donors feel good about themselves. There are a few cases where scholars have done head-to-head comparisons of a specific topic and found that ancient Rome or late medieval (sorry--better evidence than 11C) comes out a tiny bit ahead. But in the balance, which era's cities were the bigger population sink is probably a wash.
I'm going to focus on one particular aspect here: sanitation. Because you can never know enough about shit about shit.
The major reason cities were so unhealthy was disease, and this is primarily the mundane tragedy of infants dying of dysentery rather than the drama and terror of a specific plague. And so we're dealing with germs (before germ theory) and things that spread them, like people in too-close proximity, piles of excrement, and people in too-close proximity to piles of excrement.
Craig Taylor compared ancient Rome and late medieval London's strategies for dealing with waste disposal, and placed them pretty much equal in effectiveness with some slight differences in strategy. He outlines the major problems, including:
Victor Hugo spends six and a half chapters on the history of the Paris sewer system. But we'll just skim through "ancient Rome and medieval western European cities had systems of open sewers, generally flowing towards a river." Taylor argues, however, that cesspit were the preferred dumping ground if possible--ancient Roman buildings were seldom connected directly to the sewers.
There's more evidence for domestic sewer connections in the Middle Ages than he thinks, though, especially in the case of enclosed sewers. The flipside of that is that supposedly freshwater channels were sometimes used as sewers, a neighborly dispute that shows up repeatedly in court records.
To isolate human excrement, Rome did have the benefits of the amphorae system--streetside pots for people (presumably men) to pee in. Medieval cities had...the sides of buildings. But both eras did feature public latrines, such as London's delightfully named "Pixie House." Tenement buildings sometimes had their own latrines, as did private homes. And for the Middle Ages, archaeological studies of formal, commercial inns show a strong tendency to make sure the latrine wasn't next to the kitchen.
Typically, public and private latrines were located over cesspits. That created three challenges: (1) maintaining the cesspit (2) cleaning the cesspit (3) suing your next-door neighbor when they dug their cesspit too close to your property line. I actually don't know how Rome managed the first--probably taxes?--but the late medieval Church and civic organizations hilariously convinced rich people that donating in their will money to maintain a city's latrines was an excellent way to reduce their time in purgatory.
Both eras, too, had sanitation workers. Taylor mentions enslaved men in Rome, along with laborers who charged a sliding scale of fees based on the difficulty of a particular job. Fifteenth-century Nuremberg, on the other hand, made sure its city-employed sanitation workers made some of the highest unskilled-laborer salaries in the city.
Taylor does give the slight edge between Rome and (specifically) London in that late medieval London kept having to create new waste dump sites, and wasn't necessarily able to isolate them enough from surrounding human habitation.
Another problem faced by medieval cities was dirty rivers. Now, contrary to popular belief, medieval people understood perfectly well that some water was safe to drink and some wasn't; they understood perfectly well that boiling water could make some of it safe. (Don't drink the Dead Sea.) But whether it was washing or drinking, sewage-contaminated water was a major problem. One of the people I study, Elisabeth Achler von Reute, was a living saint whose stigmata bled so much that her fellow nuns had to haul her bedsheets to the river to wash every day. The townspeople of Reute started to complain that the blood was making their water unsafe.
So London tried to pass laws regulating where people could dump water into the Thames, rather than "whether." They were not entirely effective. But Rome had the problem of flood season, when river water would back up into the open sewer system and, erm, displace the sewage.
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If you'd like to read more about medieval sewers and haunted (really) toilets, you can check out the chapter "How to Cross the Cursed Swamp" in my book How to Slay a Dragon: A Fantasy Hero's Guide to the Real Middle Ages!