John Mazziotta pulled out a neurology textbook with pictures of a woman kneeling and praying next to a man who was also kneeling and praying. The woman, Mazziotta explained, had suffered brain damage and could no longer inhibit certain actions. She had not the slightest interest in kneeling and praying at that moment, but she could not stop herself from doing what brains want to do, imitate the action they see, like a monkey behind the glass at a zoo, making faces back at you.

Another thing to remember, Mazziotta said, is that many of the brain’s systems are running all the time. “Think of an airplane,” said Mazziotta. “Most people think that when it lands it has its engines on low and it’s just floating in. But that’s not always so; in landing, an airplane often has to be at full throttle in case it has to react quickly if something happens.” The brain, too he says, is set up to be whirring all the time. Even when we think of it as resting, its neurons are often firing at a low level, ready and waiting, so it can react in time before, for instance, it’s eaten by a bigger, quicker brain.

The brain is working constantly, and one of the tasks it works at is to inhibit itself from a variety of actions. It is striving to resist the urge to raise the coffee cup like the guy across the table, and striving not to do a number of things that might not be in its best interest. As the brain develops- in children and, science is now learning, in teenagers- it is this very inhibition machinery that is being fine-tuned.

“Development,” says Mazziotta, "is progressive inhibition.”

Barbara Strauch, The Primal Teen