David Dobbs' cover story about teen brains in The National Geographic nicely captures the state of research on teen brain development. ( See his blog Neuron Culture on Wired for a list of sources for the article). You probably remember some version of this story: hey, don't blame teens for that impulsive, crazy behavior...their brains aren't finished yet. Dobbs looks at it from an evolutionary point of view and reaches a different conclusion:
The story you're reading right now, however, tells a different scientific tale about the teen brain. Over the past five years or so, even as the work-in-progress story spread into our culture, the discipline of adolescent brain studies learned to do some more-complex thinking of its own. A few researchers began to view recent brain and genetic findings in a brighter, more flattering light, one distinctly colored by evolutionary theory. The resulting account of the adolescent braincall it the adaptive-adolescent storycasts the teen less as a rough draft than as an exquisitely sensitive, highly adaptable creature wired almost perfectly for the job of moving from the safety of home into the complicated world outside.
This view will likely sit better with teens. More important, it sits better with biology's most fundamental principle, that of natural selection. Selection is hell on dysfunctional traits. If adolescence is essentially a collection of themangst, idiocy, and haste; impulsiveness, selfishness, and reckless bumblingthen how did those traits survive selection? They couldn'tnot if they were the period's most fundamental or consequential features.
The answer is that those troublesome traits don't really characterize adolescence; they're just what we notice most because they annoy us or put our children in danger. As B. J. Casey, a neuroscientist at Weill Cornell Medical College who has spent nearly a decade applying brain and genetic studies to our understanding of adolescence, puts it, "We're so used to seeing adolescence as a problem. But the more we learn about what really makes this period unique, the more adolescence starts to seem like a highly functional, even adaptive period. It's exactly what you'd need to do the things you have to do then."