Book - The Psychology of Interpersonal Behaviour by Michael Argyle

I started reading The Psychology of Interpersonal Behaviour by Michael Argyle to help my FMP along. I found this extremely interesting as the part of the book I focused on talked about how communities come to exist.
It explained that communities 'become cohesive' under certain conditions such as:

"Physical proximity, e.g. sharing an office;
similarity of background, values, interest;
rewarding experiences in the group, including success at tasks;
activities which require co-operation;
a skilled leader, who can preserve harmony;
the absence of hostile or disturbed personalities."

I had never really given much thought into how a community would be formed so this really opened my eyes as it was relevant to myself and friendship groups also.