Another factor I'd mention is, ironically enough, government social programs. Humans were always social because they needed each other. If you don't depend on your community or your family, you'll be much less inclined to invest in those relationships. It used to be if you fell on hard times you might rely on your community to help you out, which would however require you to take part in it, and contribute to it in some way. If instead you just automatically get money or housing from some faceless govt institution, that incentive is removed. Black children growing up in one-parent households was 9% in the 1950s. Today it's 65%. It's controversial what the causes are of course, but it makes sense: Make it easier for people to replace their relationships with government assistance, and it removes any need for taking responsibility for your peers. I'm not saying government-provided social safety nets should be abandoned, but the devaluing of human connection – even if transactional – is an unintended social consequence that isn't talked about nearly enough.