I was surprised when I learned that adolescence was first described in the early 20th century. That was around the same time children stopped regularly working with their parents in the family business/farm. As a society, parents have abdicated the "final transision" to adulthood to the school systems, but that isn't working, so kids have no clear path to "adulthood" and, instead, wander aimlessly. Personally, I thin…
To me, it seems pretty obvious that all the adolescent tribulations are a cry for independence. The individual feels they're already at the point where they can take off on their own, but everything else around them beats them back down.
But without the experience of that first failure, and overcoming it with the guidance and support of people around them, these teenagers continue to demand their independence and fail to find any proof of their own self-worth long into their twenties and middle age...