The teenage brain: Why some years are (a lot) crazier than others | Robert Sapolsky | Big Think
[Music] Neurobiologically, the single most important fact about, say, a 20-year-old brain is the fact that almost all of it is already matured, fully wired up—myelinated, jargony term for it. The reward dopamine system has been going full blast since somewhere around like early puberty. All of the brain is totally up to speed, except for the frontal cortex.
Probably the most interesting fact about human development is the frontal cortex is the last part of the brain to fully mature. It is not completely online until you're about 25 years old, which is mind-boggling to think about. What does that explain? That explains why adolescents are adolescent in their behavior. The sensation-seeking and the risk-taking, and the highs are higher and the lows are lower because the steadying frontal cortical hand isn’t fully up to speed yet.
Everything else is a gyroscope out of control, and that's where the impulsivity is from. That's where the extremes of behavior come from. That is why most crime is committed by people at a stage whose frontal cortex is not fully developed yet. That is why most people who do astonishing, wondrously self-sacrificial things don’t have a frontal cortex that's fully in gear yet either and are not in a position to convince themselves yet that it’s somebody else's problem and look the other way.
That's why young adults are exactly how they are—because the frontal cortex isn't quite there yet. What you have as a result is more adventurousness, more openness to novelty, and more likelihood of seeing somebody who is very different as, in fact, not so being that different after all. It also leads to a greater likelihood of grabbing a cudgel and smashing in somebody's skull who happens to seem like them. The tone of everything is pushed up.
One incredibly important implication of that is if the frontal cortex is the last part of the brain to fully mature, that means it’s the part of the brain that is most sculpted by experience and least constrained by genes. It's the most interesting part of the brain. Meanwhile, look at the other end of it—look at 60-year-olds and what's going on there. If you were a 60-year-old human or, say, a rat equivalent of a 60-year-old, you were far more closed to novelty than a 20-year-old or an adolescent rat.
Take a rat for example and see at what points in life it is willing to try a new food. It’s exactly the equivalent of late teenage years to early adulthood. Then, you can close the novelty; any species out there shows that pattern, including humans. A 60-year-old is resistant to change, resistant to somebody else's novelty.
A 60-year-old, unlike a 20-year-old, deals with stress in a very particular way. If you're 20, what stress management is about is trying to overcome the stressor and defeat it. If you're 60, what stress management is about is learning to accommodate what things you're not going to be able to change. There’s nothing you can do about the fact that your knees hurt like hell.
It’s accommodating—it’s learning the difference between what you can change and what you can't. If you're 20, there's nothing in the world you can't change. By the time you're 60, what knowledge, which intelligence is mostly about, is crystallized fact-based knowledge and crystallized strategies for dealing with that knowledge.
What a 20-year-old's intelligence is about is fluid improvising, changing of set, reversing of orders—all of that is a very, very different sort of picture. 20 and 60-year-old brains, as well as 20 and 60-year-old social norms, are remarkably different.
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