The evolutionary advantage of the teenage brain

December 7, 2017 by Andy Murdock, University of California, Los Angeles
The evolutionary advantage of the teenage brain
Compared to children and adults, teens show greater levels of activation in the brain's reward center. Credit: University of California

The mood swings, the fiery emotions, the delusions of immortality, all the things that make a teenager a teenager might just seem like a phase we all have to put up with. However, research increasingly shows that the behaviors of teenagers aren't just there to annoy parents, they serve a real evolutionary purpose.

Changing minds

What is a teenager? Our standard definition is arbitrary: If your age ends in "-teen," you're a teenager. The brain, however, follows a different set of rules.

"From a neuroscience perspective, we know that the brain keeps growing and developing," said Adriana Galván, associate professor of psychology at UCLA and director of the UCLA Developmental Neuroscience Lab. "Current literature suggests that it's around age 25 or so when the brain finishes the period of adolescence."

It's not that the brain stops changing—every time we learn something new, our brain changes—but by around 25, our brain has finished its long process of structural development. For , not only is the brain still very much in development, but different regions of the brain are changing at different rates, with important consequences.

"What that means is the regions in these different parts of the brain keep refining themselves," said Galván. "In particular, there's greater activation in emotion centers deep in the brain, and there's also continued development of the , which is found right above the eyes."

The prefrontal cortex is what allows us to think about the future, to understand consequences, and generally make better decisions. Not surprisingly, the prefrontal cortex of teens still has a lot of work to do to grow into adulthood.

One way to think about it is that brain has two sides, an impulsive side, and a cautious side, that balance one another.

Before we reach adulthood, the impulsive side of the brain is charging ahead, while the cautious side of the brain is still playing catchup. The result is a .

"The analogy is that these two are kind of going head-to-head. And then eventually, as individuals become adults, the prefrontal cortex will win out, and have more influence over than the impulsive part of the brain," said Galván.

The game of risk

Credit: University of California

The delayed development of the prefrontal cortex might not be a simple side-effect of human development. Teen behaviors that grownups often dismiss as mere annoyances are actually adaptive traits that help teens learn and succeed, Galván and others have found.

Teenage behaviors aren't unique to humans: adolescent chimpanzees, for example, begin courtship behaviors, play less, and increase their grooming of other, among other changes.

While some teens can appear chimp-like at times, humans have their own unique set of adolescent behaviors, including increased risk-taking and the onset of powerful emotions that weren't present in childhood.

"Risky behavior, regardless of what the risk is, taps into the very same neural regions that process reward," explained Galván. "So when you experience a risk in a positive way, the activation is the same as if you experienced a reward."

Galván's research has found that not only are teens more sensitive to rewards than adults, this makes them better learners.

"Compared to adults, adolescents have more [reward center] activation when they're learning a new task, and this greater activation helps them learn from the environment in a more adaptive and efficient way than the adults," said Galván. "It's kind of a surprising result."

High emotions may also benefit teens in ways that even the teens themselves likely don't appreciate.

"There is probably an evolutionary reason for why teenagers are more . One reason is that emotions help us connect with other people," said Galván. "Emotions also serve as an important learning tool. When you feel a particular emotion, you're more likely to remember the event."

If something negative happens, the emotions you experience will help you steer clear of those events in the future. Positive emotions will reinforce a behavior, making you more likely to repeat it.

If Galván could bust one myth about teenagers, it's that teenagers should be quieted down until adulthood.

"The idea that the adolescent years don't serve a purpose other than annoying parents or hanging out with friends, is, I think, misguided," said Galván. "All of the experiences that happen during adolescence are important for the individual's growth."

Explore further: Why teens take risks: It's not a deficit in brain development

Related Stories

Why teens take risks: It's not a deficit in brain development

August 16, 2017
A popular theory in recent neuroscience proposes that slow development of the prefrontal cortex - and its weak connectivity with brain reward regions - explains teenagers' seemingly impulsive and risky behavior. But an extensive ...

Why it's time to lay the stereotype of the 'teen brain' to rest

October 30, 2017
A deficit in the development of the teenage brain has been blamed for teens' behavior in recent years, but it may be time to lay the stereotype of the wild teenage brain to rest. Brain deficits don't make teens do risky things; ...

Brain study reveals how teens learn differently than adults

October 5, 2016
Scientists have uncovered a unique feature of the adolescent brain that enriches teens' ability to learn and form memories: the coordinated activity of two distinct brain regions. This observation, which stands in contrast ...

Study suggests risky aspects of teen brains can be tamed by circumstances

March 10, 2017
An international team of researchers has found that despite having brains that make them more risk-prone, recklessness by teens is not an inevitable part of adolescence. In their paper published in the journal Developmental ...

Decisions and stress and adolescents

June 21, 2011
Stressing out about a boyfriend or girlfriend or history test is part of a typical day for a teenager. But what is making these insignificant events seem like the end of the world?

Study charts development of emotional control in teens

June 7, 2016
In the midst of all the apparent tumult, intense emotion, and occasional reckless behavior characterizing the teenage years, the brain is, in fact, evolving and developing the neural circuits needed to keep emotions in check. ...

Recommended for you

Precision neuroengineering enables reproduction of complex brain-like functions in vitro

November 14, 2018
One of the most important and surprising traits of the brain is its ability to dynamically reconfigure the connections to process and respond properly to stimuli. Researchers from Tohoku University (Sendai, Japan) and the ...

A 15-minute scan could help diagnose brain damage in newborns

November 14, 2018
A 15-minute scan could help diagnose brain damage in babies up to two years earlier than current methods.

Older adults' abstract reasoning ability predicts depressive symptoms over time

November 14, 2018
Age-related declines in abstract reasoning ability predict increasing depressive symptoms in subsequent years, according to data from a longitudinal study of older adults in Scotland. The research is published in Psychological ...

New research has revealed we are actually better at remembering names than faces

November 14, 2018
With the Christmas party season fast approaching, there will be plenty of opportunity to re-live the familiar, and excruciatingly-awkward, social situation of not being able to remember an acquaintance's name.

New brain imaging research shows that when we expect something to hurt it does, even if the stimulus isn't so painful

November 14, 2018
Expect a shot to hurt and it probably will, even if the needle poke isn't really so painful. Brace for a second shot and you'll likely flinch again, even though—second time around—you should know better.

The illusion of multitasking boosts performance

November 13, 2018
Our ability to do things well suffers when we try to complete several tasks at once, but a series of experiments suggests that merely believing that we're multitasking may boost our performance by making us more engaged in ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Dec 07, 2017
I hold to the opinion that the evolutionary advantage of adolescent risky behavior is two-fold. First, the young males are forced to the outskirts of their tribe.

Many communities refused to feed their young males. That meant they had to clever enough to steal food or get a good beating. Toughens them up, don'tcha know?

And has them spread out hunting. An unofficial perimeter guard against human and animal predators. Their limited intellect concentrated on filling their stomachs and running down careless females.

Pay more attention to their environment and fending off competing hunters. Cause when you hunt the lion? He's hunting you, right back. As much as you want to get your spear into the lion? He wants to get you into his belly! Reflexes are what makes the difference between becoming a lion's meal or becoming an ancestor!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.