You might like to read this article about an experiment that explains why people behave differently in cities. John B. Calhoun raised many generations of mice in an enclosed "city" to observe how their behavior changed as population density grew to intolerable levels.
The result? The mice began to exhibit many of the same neurotic maladaptations to overpopulation that humans have.
I have heard about the experiment before☺ Sometimes I miss to open my car's door freely without a car near it.