Teenage Alcohol Consumption

I'd like to start by saying that I don't believe prohibition is an option.  Alcohol is a fundamental part of our culture, and trying to take it away from people will only cause trouble (just look at the twenties).  Sex and alcohol were the reason humans settled down and developed civilization in the first place, so what kind of sad society would we be living in where those two things weren't readily available.
       Now obviously, there are problems with alcohol, such as drunk driving, the addictive effect it has on certain victims, and excessive teenage consumption.  The reason teenagers are so good at drinking and so bad at stopping (as demonstrated in recent movies like Project X, and TV shows such as Skins), is  because during the vulnerable stage of their life when they are learning how to drink moderately, instead of having guidance they are forced to indulge in secrecy.  They have no mature adults present to suggest when they've had too much.
     Of course, there's a good reason that it's illegal for youth to purchase or possess alcohol.  Until the brain is fully formed I don't doubt that there's a large risk poised by alcohol (although this didn't stop Victorian children from drinking beer three meals a day).  But is the excessive age limit of 21 really a wise decision?  In many countries alcohol is legal to citizens at the age of 18, but only mild alcohols such as beer and wine.  That way they have time to learn moderation before they are introduced to stronger concoctions.
      Anyway, this was a rather neat article I found about global age limits for drinking.      

 http://www2.potsdam.edu/hansondj/LegalDrinkingAge.html