In the book “A Troublesome Inheritance”, the author makes the case that selection on youthful traits is responsible not only for domestication in animals but civilization in humans. City life forces us to be a lot less territorial and violent towards non-family members than when our ancestors were hunter-gatherers wandering wide open spaces.
That must explain why Chicago is such a happy go lucky place but rural areas are virtual battlegrounds.
Ok, I admit, that was a wee bit snarky.
Sounds like a good theory, but why are cities so high in violent crime as opposed to country towns? Country town folk all know each other, as would a tribe. You can get lost in a city.