I have long suspected that large population densities are bad for humans. How bad? Look at the resulting population of every major city in the world, and you come to the conclusion, Very Bad.
What is bad? Bad is families breaking down. People turning their back on social norms that promote harmony and peace of society. Crime, sloth, and acceptance of the perversion of social norms eventually becoming common place.
I ran into this study showing what happens to rodents in a simulated urban center.
The summary is that males lose their purpose and eventually become asexual. Females lose mothering instincts and eventually become infertile. The population literally dies out completely, not because of disease or violence, but because it turns its back on all its social norms that originally led to reproduction of the species.
This leads to an insight and a question.
First, if you want to have descendants for as long as there are people on this earth, teach your children to live in the countryside away from urban centers.
Second, the question. Should dense urban centers be banned for the good of culture, society, and the existence of our species? Should there be a legal limit to population density? Honestly, I don’t know, but I think this study says, “Yes.”
(source: “Death Squared: The Explosive Growth and Demise of a Mouse Population” by John B Calhoun MD, Proc. roy. Soc. Med. Vol 66 Jan 1973)