Social exclusion no longer means death for humans, but our brains are wired to feel that it does, and so there is an epidemic of loneliness, disconnection, and fear.

I'm not saying that the old days of completely depending on one's tribe of family and friends for survival was better in objective terms, but it was harmonious with our evolved instincts to be part of a small, mutually-connected group. Economic and social forces in a globalized society tend to act against the sustainability of such groups. So even those who are well-connected aren't as deeply connected, and are always threatened with potential loss of connection for unpredictable, uncontrollable economic or social reasons.

[1]: http://www.npr.org/2016/05/21/478962909/sebastian-junger-s-e...

Only because "society" is too large. For millions of years, "society" meant the same as "others", who were a hundred or so folks in your particular band of primates. You could have a personal understanding with each one of them.

Now that "society" is 7 billion anonymous people, of course you don't matter in that context. Concepts like "universal brotherhood" make no sense, because meaning and belonging don't scale.