The teenage brain: Why some years are (a lot) crazier than others
Neurobiologist Robert Sapolsky explains how your first 25 years will shape the next 50.
Robert M. Sapolsky holds degrees from Harvard and Rockefeller Universities and is currently a Professor of Biology and Neurology at Stanford University and a Research Associate with the Institute of Primate Research, National Museums of Kenya. His most recent book is Behave: The Biology of Humans at Our Best and Worst.
ROBERT SAPOLSKY: 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, a jargon-y 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 that 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; the highs are higher and the lows are lower, because the steadying frontal cortical hand there isn't fully up to speed yet, and everything else is a gyroscope out of control. And that's where the impulsivity is from. And that's where the extremes of behavior, and that's 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 the frontal cortex that's fully in gear yet either, and it's not in a position to convince them yet, 'Ah, that's somebody else's problem. Look the other way.'
That's why young adults are exactly how they are. Because the frontal cortex isn't quite there yet, and what you have as a result is more adventurousness and more openness to novelty and more likelihood of seeing somebody who's very different as, in fact, not being that different after all. And more likely to grab a cudgel and smash in somebody's skull who happens to seem like a "Them". And everything, just the tone of everything, is pushed up.
One incredibly important implication of that is that if the frontal cortex is the last part of the brain to fully mature it means it's the part of the brain that is most sculpted by environment and experience—and least constrained by genes. And 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 are a 60-year-old human, or say a rat equivalent of a 60-year-old, you are far more closed to novelty than a 20-year-old, than an adolescent rat is. Take a rat, for example, and see at what points in life is it willing to try a new food. At exactly the equivalent of late teenage years, early adulthood, and then you're closed to novelty. Any species out there shows that pattern including humans. So a 60-year-old is resistant to change, is 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, and 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 intelligence is mostly about is crystallized, fact-based knowledge and crystallized strategies for dealing with that knowledge.
What a 20-year-old intelligence is about is fluid, improvising, changing of set, reversing of orders. All of that is a very, very different sort of picture. So 20- and 60-year-old brains and 20- and 60-year-old social worlds are remarkably different.
- The human brain isn't fully developed until 25 years of age. Everything is there except for the frontal cortex, which is the last thing to mature.
- An immature frontal cortex explains the spectrum of teenage behaviors: it's what makes adolescents adolescent, says Sapolsky. "The sensation-seeking and the risk-taking; the highs are higher and the lows are lower," he says. Teenagers are more adventurous and more heroic during this time—but can also be more violent and impulsive.
- Because your frontal cortex is the last part to develop "it's the part of the brain that is most sculpted by environment and experience—and least constrained by genes," Sapolsky says. That's great news! Your adventure levels, openness, experience, and influences at 25 years old will shape who you are when you're 60.
We all know sleeping with your ex is a bad idea, or is it?
- In the first study of its kind, researchers have found sex with an ex didn't prevent people from getting over their relationship.
- Instead of feeling worse about their breakup after a hookup, the new singles who attempted sexual contact with their ex reported feeling better afterwards.
- The findings suggest that not every piece of relationship advice is to be taken at face value.
Want a happy, satisfying relationship? Psychologists say the best way is to learn to take a joke.
- New research looks at how partners' attitudes toward humor affects the overall quality of a relationship.
- Out of the three basic types of people, people who love to be laughed at made for better partners.
- Fine-tuning your sense of humor might be the secret to a healthy, happy, and committed relationship.
Tiny and efficient, these biodegradable single cells show promise as a way to target hard-to-reach cancers.
- Scientists in Germany have found a potential improvement on the idea of bacteria delivering medicine.
- This kind of microtargeting could be useful in cancer treatments.
- The microswimmers are biodegradable and easy to produce.
Metin Sitti and colleagues at the Max Planck Institute in Germany recently demonstrated that tiny drugs could be attached to individual algae cells and that those algae cells could then be directed through body-like fluid by a magnetic field.
The results were recently published in Advanced Materials, and the paper as a whole offers up a striking portrait of precision and usefulness, perhaps loosely comparable in overall quality to recent work done by The Yale Quantum Institute. It begins by noting that medicine has been attached to bacteria cells before, but bacteria can multiply and end up causing more harm than good.
A potential solution to the problem seems to have been found in an algal cell: the intended object of delivery is given a different electrical charge than the algal cell, which helps attach the object to the cell. The movement of the algae was then tested in 2D and 3D. (The study calls this cell a 'microswimmer.') It would later be found that "3D mean swimming speed of the algal microswimmers increased more than twofold compared to their 2D mean swimming speed." The study continues —
More interestingly, 3D mean swimming speed of the algal microswimmers in the presence of a uniform magnetic field in the x-direction was approximately threefolds higher than their 2D mean swimming speed.
After the 2D and 3D speed of the algal was examined, it was then tested in something made to approximate human fluid, including what they call 'human tubal fluid' (think of the fallopian tubes), plasma, and blood. They then moved to test the compatibility of the microswimmer with cervical cancer cells, ovarian cancer cells, and healthy cells. They found that the microswimmer didn't follow the path of bacteria cells and create something toxic.
The next logical steps from the study include testing this inside a living organism in order to assess the safety of the procedure. Potential future research could include examining how effective this method of drug delivery could be in targeting "diseases in deep body locations," as in, the reproductive and gastrointestinal tracts.
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