I don't think human interaction is necessary at all.  Of course children need to be raised in the context of families, but once 'acculturated' --especially in today's world of electronic media there is no reason for people not to enjoy being alone.  I know many people like myself, who garden, build things, write, and rarely if at all ever interact with other people. For the most part, I find people who think I need their friendship to be a nuisance, and it is problematical how I can get them out of my life without hurting their feelings.  I see such "needy" people as psychologically deficient.