This contradicts a theory proposed (separately, as far as I know) by Eliezer Yudkowsky and psychologist Richard Epstein. They argue that the troubles of adolescence are caused by the unnatural situation society places teenagers in - segregated in high schools, denied autonomy, and lacking responsibility.

As Yudkowsky puts it:
"Physiologically adult humans are not meant to spend an additional 10 years in a school system; their brains map that onto "I have been assigned low tribal status". And so, of course, they plot rebellion - accuse the existing tribal overlords of corruption - plot perhaps to split off their own little tribe in the savanna, not realizing that this is impossible in the Modern World. The teenage males map their own fathers onto the role of "tribal chief"..."
http://www.overcomingbias.com/2008/07/rebelling-withi.html

And Epstein:
"Imagine what it would feel like—or think back to what it felt like—when your body and mind are telling you you're an adult while the adults around you keep insisting you're a child. This infantilization makes many young people angry or depressed, with their distress carrying over into their families and contributing to our high divorce rate. It's hard to keep a marriage together when there is constant conflict with teens.
...
In most nonindustrialized societies, young people are integrated into adult society as soon as they are capable, and there is no sign of teen turmoil. Many cultures do not even have a term for adolescence. But we not only created this stage of life: We declared it inevitable. In 1904, American psychologist G. Stanley Hall said it was programmed by evolution. He was wrong.
...
Dumas and I worked out what makes an adult an adult. We came up with 14 areas of competency—such as interpersonal skills, handling responsibility, leadership—and administered tests to adults and teens in several cities around the country. We found that teens were as competent or nearly as competent as adults in all 14 areas. But when adults estimate how teens will score, their estimates are dramatically below what the teens actually score.
...
The adversarial relationship between parents and offspring is terrible; it hurts both parents and young people. It tears some people to shreds; they don't understand why it is happening and can't get out of it. They don't realize they are caught in a machine that's driving them apart from their offspring—and it's unnecessary.
...
I believe that young people should have more options—the option to work, marry, own property, sign contracts, start businesses, make decisions about health care and abortions, live on their own—every right, privilege, or responsibility an adult has. I advocate a competency-based system that focuses on the abilities of the individual. For some it will mean more time in school combined with work, for others it will mean that at age 13 or 15 they can set up an Internet business. Others will enter the workforce and become some sort of apprentice. The exploitative factories are long gone; competent young people deserve the chance to compete where it counts, and many will surprise us."
http://www.psychologytoday.com/articles/index.php?term=pto-2...

Of course, I don't have sufficient information to judge who is right, or whether the two theories can be reconciled. It would be interesting to hear Yudowsky and Epstein respond to Giedd's work, and vice versa.