[foolmeonce]

I'm not sure I believe this diagnosis. I think communications has made for more formal estrangement since it's pretty hard to find a lifestyle that explains why you can't video chat from anywhere anytime and the cost of even trans-continental travel is rarely a quarter of a year's salary.

The further you go back, the easier it was to have excuses to greatly limit contact and only have contact that is very impersonal. The average American is a decendant of adults who were never going to see their parents again. Most would have felt a great deal of social pressure to treat that as a hardship and disguise if it was their primary motivation.

I think hunter gatherers would have been predisposed to finding new groups at adolescence even if their culture lacked a specific rule for which sex does so, and the priorities of agricultural societies to keep land rights are probably not particularly compatible with our evolutionary past.