Significance of the age of 21

[violaine]

Why, in the past, was the age of 21 considered the age when a person officially became an adult, as opposed to, say, the age of 20? And these days, what legal rights do you gain at 21 that you don't get at 18?

[rja211077]

can't answer first part of question but for 2nd part...you can't be an MP until 21

[Ewood27]

It was believed (sorry, I don't know by whom) that the body renewed itself over the course of every seven years and that it had to go through three complete stages before it could be called adult.