I think the development has gone on as people have moved to bigger cities, and increased their exposure to other human beings. In the old days, we only interact

I think the development has gone on as people have moved to bigger cities, and increased their exposure to other human beings. In the old days, we only interacted with 10-20 people on a daily basis(your butcher, your barber, your few co-workers, etc). Now, living in large cities, we have interact/encounter with hundreds of random strangers everyday.