We learn that youths take risks that terrify their parents because - as scientists have discovered through modern brain-scanning technology - the teen brain isn’t fully cooked — it’s still in the process of rewiring and remodeling itself and maturing toward adulthood. Our brains have networks of neurons that weigh the costs and benefits of potential actions, but teens weigh those consequences in peculiar ways.
The first full series of scans of the developing adolescent brain in a National Institutes of Health (NIH) project showed that our brains undergo a massive reorganization between our 12th and 25th years. Physical brain growth is negligible during this period as it has already attained 90 percent of its full size by the time a person is 6 years old. During the process of maturation, physical changes move in a slow wave from the brain's rear to its front, from areas that look after behaviorally basic functions, such as vision, movement, and fundamental processing, to the evolutionarily newer and more complicated thinking areas up front.
The long, slow, back to front developmental wave, completed only in the mid 20s, appears to be a uniquely human adaptation. This delayed completion of the fore brain's myelination — the myelin coating that greatly accelerates a brain's bandwidth, also inhibits the growth of new branches from the axon (the long nerve fibers that neurons use to send signals to other neurons) - is a withholding of readiness that heightens flexibility just as we confront and enter the complicated world of adulthood. Here's the kicker: if we smartened up sooner, we'd end up dumber.
B. J. Casey, a neuroscientist at Weill Cornell Medical College, puts it this way, "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."
The long National Geographic article may explain why some youngster posted a hilarious video while others were bawling their eyes out, but it still does not explain why an adult would want to snip off bits of anatomy.