This article, by an obviously intelligent teen, extolls the reasons for lowering the drinking age back to age 18. It shows how even well-meant commentary can fail to consider all sides of an issue.
My response to the article follows.
Recent research has shown that the human brain is not finished developing until around age 22. Up until that time, even occasional overindulgence in alcohol (more that 1 drink a day for women, two for men) can cause abnormalities in the neural connections between the two sides of the brain and within both hemispheres. Even one binge (more than five drinks in two hours) can disrupt this development significantly.
There is a lot of literature on this issue. I suggest beginning with this article: http://www.nytimes.com/2006/07/04/health/04teen.html