Comments in a recent post, and elsewhere, have raised the issue in relation to child marriages. I'm more recently familiar with the developmental-psych bases for adolescence, but I recall studying its cultural and economic development many years ago, in connection with some Foucault-heavy grad seminars in the early 80s. However, I'm not a current expert.
I'm sure this would be a highly interesting topic, as it affects so many other historical issues, and also because we have many redditors in that age group.
I'll copy and paste my answer from the other thread.
This is a pretty solid article. Adolescence as a well-defined category/life-stage is relatively recent. G. Stanley Hall invents the term to describe a period of sexual maturity without intellectual maturity. Hall is an interesting figure; he had a very controversial worldview which absolutely leaked into his work. That work was very much a part of the psychological zeitgeist for decades, leading to a protectionist attitude towards adolescents instead of a permissive one.
To expand briefly on Hall, he was a staunch believer in the Volk, because he believed the natural state of people was to be uncivilized, and that they needed to be forcibly civilized in order for human society to progress. Freud, another significant contributor to early developmental psych, identified similar ideas but without so much political interest. The movement to remove children from the workforce and the establishment of highschool to move the workforce out of unskilled labor and into skilled labor grafts these ideas, alongside a peculiarly Enlightenment notion, that the child was created a pure being of nature which the world corrupted. So you have childhood concatenated with adolescence, with a wider societal movement to protect the children. This very much suggests our modern treatment of adolescents.
The term adolescence exists prior to Hall, but Hall codified it. While this falls well within the 20 year rule, I think it's worth mentioning that there is a controversial trend to extend adolescence by several years, into the 20s. Due to said rule, we can't discuss it too in-depth, but there is it for you to read.
hi! there have been a few discussions on this question - check out these posts:
What was the concept of childhood before Victorian times?
No. Until the early modern period in Euro-American history, there seems to be little to no concept of adolescence. Here is a chart showing its use over time: http://thesocietypages.org/socimages/2011/02/23/the-invention-of-adolescence/
The most famous criticism of conceptions of adolescence is probably Margaret Mead's work, the popular Coming of Age in Samoa and the technical The Social Organization of Manu'a.
In ancient China, 20 is the age a male becomes an adult. You get a ceremony where you wear a hat, call "weak hat". Age 15-20 is call "dancing elephant" and you can join the military at that age. If you consider the years before you are an adult to be adolescence, then "dancing elephant" would be it.