Living beings are here only because their ancestors reproduced in the past. This must be true since all living beings have a finite lifespan. This principle is true to the extent that some people even go as far as defining reproduction as the primary purpose of life, if the word purpose can be used here without controversy.
Adolescence is when the earliest signs of reproductive urges appear, even though in modern times people usually do not reproduce until sometime later. Biological urges, on the other hand, do not care for modern regulations, laws, or social constructs. They only change through a slow evolutionary transformation and this transformation will not take place if the said transformation brings no reproductive or survival related advantages. Therefore, the mere passage of time will not lead to a change in adolescent behavioral patterns.
What are these behavioral patterns? Why do young males and females behave a certain way? Perhaps more importantly, why are these behaviors considered irrational, risky, crude or sometimes even cruel by the rest of the age groups?
Adolescents are generally seen as irrational in many ways. They will perform some wildly dangerous acts only to gain the slightest attention from their peers or potential partners. In a world where people reproduced as early as their teen years and the only way to gain social status was physical acts of superiority, every adolescent behavior is completely rational. We could very well expect modern adolescents to understand this and adjust their behavior accordingly, but this would be an entirely irrational expectation. No matter how rational, every human being is significantly affected by their biological urges.