This means that Brian is starting
puberty. Puberty usually starts between
ages 12-16 for boys. Armpit hair, along with body odor and mild acne are a
result of DHEA hormone production. This ordinary body process during teenage
years that is related to puberty is
called adrenarche.
I believe the answer is: Giving them back.
With current development of technology and social media, we could read from various different sources and easily provided the new knowledge for other people with one single touch.
One positive thing about this is that it make the flow of information become much more easier, but one negative thing about it is that it is really hard to separate which knowledge are true and which are not.
Although there is no exact date for this, generally speaking it would be the period of the "late-1700s" that saw the beginning of the Industrial Age in the United States, since this is when machinery started played a larger role in the economy.