The brain is not interested in learning.
Period.
What the brain is interested in is surviving.
—John Medina
Anyone familiar with my concept of “authentic engagement” knows that I believe one of the pillars of effective teaching (and parenting) is a thorough working knowledge of the neuroscience about the brain, and that absolutely foundational to this knowledge is the reality that the structures and functions of the human brain did NOT evolve in the environment we now currently inhabit as a species. Indeed, it is to the peril of educator and parent alike to forget that our brains evolved under very different circumstances—the Pliocene of East Africa—and that we, correspondingly, have a brain totally fine-tuned for survival in that world, not this one.
Moreover, nowhere is this peril greater than when working with the teenage brain. As I mentioned in my previous essay, adolescents today are fundamentally no different than adolescents at the start of my career (or millennia ago for that matter), and that is why one of my critical tasks as their teacher has been to help my students navigate the massive upheaval going on inside their heads and why I suggested that there are ways to address this need successfully in our always changing world. However, I want to argue that first we must understand what’s actually going on in the adolescent brain and why it evolved to generate the kinds of behaviors we typically associate with teenagers. Only then, I think, can we figure out how to help a teenage Pliocene brain traverse the modern challenges of our digital age.
So let’s get started.
To begin with, we require a short primer on brain development in general. First, from conception to roughly age five, you grow as many possible neurons in as many regions of your brain as your environment demands (which is why Olympic level athletes nearly always start at this age—the brain grows lots of extra motor cortex neurons in response to the demand—and it is also why Head Start programs are so important to future academic success). Then, between roughly age 5 and the onset of puberty, all those new neurons reach out and grow billions of extra synaptic connections, again as your environment demands (which is why learning to read by 3rd grade is so critical).
Next comes puberty and adolescence when some time (usually!) between the ages of 10 and 13, your hypothalamus starts cranking out a hormone called kisspeptin that, to borrow a phrase, “make all hell done break loose!” It initiates the massive upheaval of changes that transform a child into a reproducible adult, and no where does this upheaval have greater impact than in the brain. Massive increases in myelination speed up neural communication rates 3,000-fold while all those earlier extra synaptic links are careful and meticulously pruned—all, as always, dependent on what the environment is telling the brain is important (and which is the neurological justification for a liberal arts education). Indeed, at no other time in our lives does the brain undergo such enormous physical change, continuing well into our early 20s.
Adding fuel to all this fire is the fact that:
Although these changes happen in all teenage brains, there’s no wholesale neurological goose-stepping. Teens go through this at their own individual paces, as diverse as political points of view. To make matters worse, even specific regions inside a single brain go through maturation process on differing schedules. (Medina, p. 63 original emphasis)
The limbic system, for example, reaches its adult form around age 15, with a 7% larger amygdala with all its pesky primary emotions (fear, want, anger, & lust); while meanwhile, the prefrontal cortex with its complex judgment and decision making centers doesn’t’ reach its adult form until as late as age 25. Hence, “teen-brain reward centers are more active than children’s or adult’s, making them experience rewards (and other feelings) more intensely than any other time. When they yell out, ‘I’ve never been so stoked in my life!’ they may be literally telling the truth” (Medina, p. 69).
What, then, are the implications for our understanding of teenage behavior? First, on the mundane level, it explains their incessant appetites for food and why they are always sleepy when they don’t get the 9 or more hours of snoozing they actually need each night. The mature brain is already one of the great energy drains on the body’s resources, accounting for only 2% of our total mass but consuming at least 20% of our caloric intake, and here we have brains under construction demands that makes building the Burj Khalifa tower in Dubai look like an assembly of matchsticks.
Second, on the less mundane, the disconnect in maturation rates between limbic and prefrontal cortex accounts for the general swings in mood and frequent risk-taking teenagers experience. A less-than-fully regulated amygdala and other limbic structures are going to have the potential to generate behaviors resembling those of the “lizard brain” for which this region is often analogized, and while it is actually the struggle to control this part of the brain that directly causes part of the prefrontal cortex maturation, some limbic decisions have resulted in their owner paying a heavy cost…sometimes, regretably, even death.
Third, and finally—and most definitely NOT mundane—the price of all this colossal change taking place in the teenage brain is that adolescence is the peak onset of mental health disorders, with 50% of diagnosable illness occurring by age 14 and 75% by age 24. The simple reality is that with so many “moving parts,” there are so many more potentail ways to have things break, just as they would with an actual mechanical machine, and that leaves the teenage brain at greatest risk for malfunctioning before it even has the chance to transform itself into a healthy fully adult brain.
Which brings me back to the evolution question: why on earth would the human brain evolve to go through what looks like from today’s vantage such a potentially dangerous developmental stage? The answer is two-fold: gene shuffling & energy. Early humans lived in small, hunter-gatherer groups where the potential threat for incest and all its accompanying genetic dangers—especially from a species perspective—was a very real problem. What better way to drive you to separate from your family right about the time you are biologically ready to reproduce and to make the dangerous trek to another tribe than to make you engage in obnoxious and annoying behaviors toward your elders and to employ a brain “cognitively anesthetized” toward taking risks? Furthermore, in a world of small, hunter-gatherer groups, energy would be very hard to come by—especially the excess energy needed to reproduce and rear young—and so what better way to conserve the need for energy than speeding up and pruning huge sections of the most energy intensive organ in the body in as short a time span as possible? Even if that meant that some individuals would not survive that cognitive rearrangement mentally intact.
Hence, what adolescence evolved to do was to ensure the necessary genetic diversity within the human species needed to adapt to an every-changing environment as well as the energy conservation in adulthood needed for individual members of the species to reproduce in a world where daily hunger was the norm. As John Medina puts it, “all of a sudden, you have a seriously powerful label for puberty: species savior” (p. 78); we literally wouldn’t be here today without the teenage brain.
Of course, today, we do not live in the Pliocene. There is more potential gene shuffling in a single American high school than existed on the entire Serengeti plain, and we actually have an obesity crisis in this country because of how much excess energy is available to us. Hence, the challenge for us as educators (and parents) today is how to manage a Pliocene brain in an industrialized digital world. Knowing how that Pliocene brain works, though, can give us clues.
More on that next time.
References
Gazzaley, A. & Rosen, L. D. (2016) The Distracted Mind: Ancient Brains in a High-Tech World. Cambridge: The MIT Press.
McKie, R. (1996) African Exodus: The Origins of Modern Humanity. New York: Henry Holt and Company.
Medina, J. (2018) Attack of the Teenage Brain. Arlington, Va: ASCD Books.
Light a Candle 