I have been arguing for years - from repeated observation - that smaller communities are kinder and more caring than bigger ones and this, "cooperation can spontaneously break out even among fundamentally selfish agents - provided you assume that people meet each other more than once, and can remember what the other person did last time they tried to strike a bargain," finally gives me a logical reason for it: you can "assume that people meet each other more than once" in a small community but not in a bigger one.
Thanks!!