I've seen it stated occasionally that pre-modern cities were population sinks; that is, their population was sustained by immigration from the surrounding countryside rather than by birth rates within the city. The explanation given is that before modern medicine and sanitation, in the crowded conditions of the city mortality due to disease was horrifically high (to us).

On the surface it seems plausible, but has anyone collected the necessary demographic data to test this? If so, was it universally true, or were there some cities that had the sanitation and public health measures to escape it? It seems implausible that the disease mortality in, say, Tenochtitlan would be as high as contemporary London.

Further (and I doubt there're data to test this, but in case someone's done it, I'll toss this question up), did pre-modern health and sanitation measures, such as aqueducts or garbage services, influence the rate or level of urbanization? That is, did cultures whose cities were safer also have cities that grew faster and sustained larger populations, resulting in higher urbanization?

I'd be especially interested in any papers on this topic that there might be, because my google scholar fu doesn't seem up to the task.

If it is, was the bridge as chaotic as it looked in the film? I always found the scene haunting and wondered if this was a real bridge that was constantly being fought over. I know the film was based on the book Heart of Darkness, so I'm pretty sure there was no truth to a mission like that.

Often times, when a political candidate refers to history, they warp it tremendously into propaganda to push their points, but what they said has a nugget of truth to it to some degree (with the notable exception of /r/badhistory favorite Ben Carson). Last night in the Republican Debate, Donald Trump said that Eisenhower repeatedly moved immigrants just south of the border, which failed, and then he moved a million illegal immigrants much further south and it was a success. I assume he's talking about Operation Wetback.

I have hear before that some Nazis in South America were found by the architecture of the homes they built. Specifically the pitch of their roofs in countries that don't see much or any snow. Is there any truth to this? I had thought that South America had a pretty strong tradition of German immigration before WWI, so wouldn't there have already been German architecture around?

I'm having a hard time looking for female artists associated with painting, drawing, etc. I've mostly seen female poets based on my research.

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Was a scientific discovery, like fundamental particles attracting to each other, or was it just a general observation that things of different nature tend to draw together?

Edit:

Damn that extra "o" in the title.

I've read that the UK and US shared a few technologies with each other, yet also kept others secret. Would really like to know an answer to this question.

I'm looking for recommendations for a book which can explain the core ideas and differences between Luther, Melanchton and Zwingli. I looked at 'Reformation: Europe's House Divided 1490-1700' but its page count and detail is not what i'm looking for.

I'm writing a paper in which these disputes have a tangential relevance and as such i need a general rather than an in depth understanding of these issues. I'd like the literature to be academic if possible.

Hoping for some great reformation era historians out there!

Thanks for reading.

Later on we see how some families delivered plenty of popes like the Borgia and Medici families. If my suspicion is correct then at the time it wasn't even so odd for a pope to have children from before he entered the pontificate functions. With that suspicion in mind it seems logical that there would have been a certain danger of sons of bishops and popes inheriting the positions of their fathers... right?

Would love to get reading recommendations on how Mediterranean piracy impacted trade and the economy of the region, from the 1500s to the 1600s.

Thanks in advance!

Also the social implications of the music and the nightclubs? Any book recommendations?

Thank you.