People are strange, when you're a stranger
We're born into a world submerged in strangers. They - the strangers - are everywhere, doing so many different things, and we know almost nothing about them. Looking around, we realize that we live between the cogs of an impersonal, gigantic clock work; and yet, we're social creatures, charged with the prime directive to interact with others. We go so far as to categorize those we've no intention of ever meeting; as we gaze at strangers we measure their appearance, and their role in our society.
Evaluating others is our species' raison d'etre. But even though we've evolved for sociability, the very scale of modern institutions and governments, strains our capacities. Our various circles - friends, family, sports, work, and others - form centres for social networks of dizzying complexities, and which we consider so important to traverse properly.
Given the scale of the modern social phenomenon, it's no surprise that those raised in cities experience increased stress; increased social stress that permanently affects the brain. It's as if the developing neural circuitry of areas associated with social stress, are vulnerable to an overload that scars for life. Cities may be a psycho-neurological analogue to foot binding.
City living is well known to be a causative factor in a host of psychological conditions, including especially schizophrenia. This effect is limited to development, specifically effecting people as they grow up in cities, but not as adults living in cities. The specific factor which underlies this effect is suspected to be "social evaluative stress", that is, the stress we feel at being judged . To be a social being is to be aware that others think of us, and this evokes almost universally some element of stress which we use to navigate our lives amongst the reefs of expectations.
Evolutionary tinkering has developed a system for determining how others think of us, using those expectations as stressors for conditioning our own behaviours. Presumably this system is correlative: the more important others' expectations are, the more the brain will adapt to being responsive to those expectations. This system would allow for various important conditioning patterns which would encourage our capacity to operate in groups, and allow groups to form meta-priorities which filter through the population by implicit expectations.
In cities this capacity is overworked, teaching the brain to either overdo or overcompensate for the conditioning patterns we associate with others. As a consequence, cities produce a new breed of people. Whether or not this new population is overall better or worse, and what other benefits or handicaps are caused by city living, remains to be discovered
Every change in our social structures is another step in a long road that began in a fading prehistory and that heads towards an unknown strange new world. From agriculture to cities to internet to whatever comes next: the traveller is the journey.
Reference: Yates, D Psychiatric disorders: the stress of city life (2011) Nat Rev Neuro: In this study the atuhors gave volunteers arithmetic tests during which they received negative feedback. Brain imaging (fMRI) was used to establish different neuronal responses which could then be correlated for urbanicity. Only the brain areas mentioned above showed any signficant urbanicity-dependent effect. A few follow up experiments were used to confirm various conclusions.