child to adult

So, the book we are studying at the moment, The Adventures of Huckleberry Finn, has a lot to do with the theme "coming of age".  Huck is becoming an adult and through our contrasts, we can see how Huck is changing into more of a mature person than he was in the beginning of the book.  My question is, what has occurred to mark his transition into manhood, if anything? Was it the death of his friend Buck? Or has he found maturity through his relationship with Jim? Is there a clear place in the book where it is visible that Huck has begun his transition into being a man?  I think that when he first went out in the canoe and was on his own, that marked the beginning of his transition into adulthood.  What do you think?

In real life, when does a child lose their innocence?  I know i wrote a blogpost earlier in the year about children believing in Santa Clause.  Is it when they stop believing in the tooth fairy?  Or when they realize that magic isn't real?  Is there a specific ritual they have to experience, such as a bar/bat mitzvah or confirmation? Is it when you finally decide that you don't need your blanket or stuffed animal or the night light?

For me, a death in the family was the first time I saw my mom and dad cry.  That was a pivotal point in my life when I first noticed that people pass on and can not be with us forever.  I saw my parents (who I thought were the toughest two people in the whole wide world) become vulnerable and scared, and that is when I began to look at things differently, my world was changed forever.  

What marks the transition into adulthood in a child's life? Is it the loss of their innocence?  What has happened in your lives that you think made you begin your transition into adulthood?