Everyone looks at the world through a lens built in high school. No one intends to, but neuroplasticity peaks in puberty so our core neural pathways develop at that time.
Humans are not born hard-wired like smaller-brained creatures. We’re designed to wire ourselves from lived experience. Whatever triggered your brain chemicals in youth paved neural pathways that turn them on today.
Early experience builds our core pathways because a young brain is full of myelin, the fatty substance that coats neurons and makes them efficient. Myelinated neurons convey electricity up to 100 times faster than undeveloped neurons. Whatever you do with your myelinated neurons feels natural and normal, from speaking your native language to getting social support in ways that worked when you were young.
Myelin is abundant before age eight and during puberty. Those first seven years lay the foundation of your neural network, and in puberty you get a chance to rework it. Of course we learn throughout life, but we mostly add leaves to existing branches. The deep branches that control your neurochemicals are built from the repeated emotional experiences of your myelin years.
Our adolescent pathways are obvious yet elusive. They’re obvious because they’re what you tell yourself all day every day. They’re elusive because they don’t match your conscious explanations of your impulses. You can penetrate that verbal veneer when you know how adolescence works in animals.
There is no free love in the state of nature. Animals work hard for any reproductive opportunity that comes their way. They persist because their brain rewards them with happy chemicals when they succeed.
Animals leave home at puberty to avoid inbreeding. They are not consciously concerned with genetics, of course, but even plants evolved ways to avoid inbreeding. Most mammals must leave their birth group to get mating opportunity (either the males leave or the females leave, depending on the species). They don’t think conceptually about conception; they just do things that promote their genes because it stimulates happy chemicals. Natural selection built a brain good at rewiring itself during puberty because that promotes survival.
A young mammal suffers when it leaves home. Without the protection of a herd or pack or troop, its cortisol surges. Cortisol feels so bad that it motivates urgent action to relieve it. Joining a new group relieves cortisol, so pubescent animals strive for new bonds. That’s harder than you might expect. Animals typically exclude newcomers to reduce competition for resources. It works without conscious intent because brains that responded to outsiders with cortisol had more surviving children. Mammals evolved brains that make careful decisions about when to accept others.
Survival takes more than just gaining admission into a group because the newcomer is now at the bottom of the hierarchy. A young mammal’s reproductive success depends on raising its status. Mammals who stay home with their birth group confront social hierarchies too. Survival rates are low in the state of nature, and many individuals die without passing on their genes. Our brains are inherited from individuals who prevailed. You might dislike the idea that mammals compete for social status, but knowing the facts helps us manage those impulses instead of yielding to them.
The brain we’ve inherited has a strong sense of urgency about social acceptance and social rivalry. Such feelings in youth pave neural pathways that shape your response to the world today. Conscious memory of those those experiences is not necessary because brain chemicals build pathways without effort or intent.
It’s easy to see the high-school impulses in others, and harder to see in yourself. But you will find your early wiring if you look. Notice the patterns in your ups and downs today and look for adolescent experience that fits the pattern. You will be amazed at the match.