This very long NY Magazine piece meditates on that topic, "Why You Never Truly Leave High School": http://nymag.com/news/features/high-school-2013-1/

I can't remember if the author states any scholarly work to support the idea, but she talks about it at length. One thing that I think is well established is that kids mostly being around other kids all day is a relatively modern phenomenon. It's a long piece, but it resonated with me.

I went searching for a great article I read on this lately but couldn't find it: the gist is that until schools become de rigueur, adolescents never spent time together as a group as they would be at work/apprenticeships whathaveyou with adult 'supervision'. It's a new phenomenon that leaves delicate minds in a Lord of the Flies situation. The study I read showed that even the 'cool' kids thought they weren't cool and the various coping mechanisms have been fodder for hollywood movies and novels since the last decades.

I found this http://www.faqs.org/childhood/So-Th/Teenagers.html that claims that schooling past the age of 14 went from rare to normal between 1901 and 1940.