That's a good point, and definitely operates over the long term (i.e., in this case, more than one generation). Also, overpopulation usually creates conditions

That's a good point, and definitely operates over the long term (i.e., in this case, more than one generation). Also, overpopulation usually creates conditions that change the community and affect individuals and subgroups differently (prompting some to leave), so I don't think we are disagreeing about anything. My purpose was to respond to the original comment that the desire to leave community is not as strange and abnormal as it seemed to state. I think there is an equally strong claim that human history is of us leaving community as it is building community.