You may feel like you have nothing in common with your family, your co-workers, and the other people at the festivities in your world. It helps to know that this feeling has a real physical cause. You really are different, because your brain wired itself from your unique life experience. They are different because their brains wired from their experiences. We're the same in some ways, of course. We all have the same urge to do things that trigger our happy chemicals and avoid unhappy chemicals. But our triggers vary widely. When you know how your triggers got built, you feel more comfortable with the differences that surround you. Let's look under the hood.
We humans are not born pre-programmed. We're born with a lot of neurons but very few connections between them. Our neurons connect from experience. That doesn't mean experiences you remember, like the time you rescued a starving village on a mountaintop by carrying food up a cliff. It means early experience, because young brains built the neural infrastructure that later experience relies on.
You were born to build your own operating system. Imagine you’re a hunter-gatherer looking for food and you stumble on a delicious berry patch. You feel thrilled, because meeting your needs triggers dopamine. Every time your dopamine was released, it built connections between all the neurons active at that moment. That wired you to find more berries and meet more needs in the future. No conscious effort is needed for dopamine to store information relevant to getting more of the rewards that triggered it.
Now imagine you are a toddler foraging with your mother. She finds berries and reacts with joy. Your mirror neurons trigger joy in you. A circuit that responds joyfully to berries can be created before you really know what berries are. This is how our ancestors learned survival skills before there were curriculum development experts. Chimpanzees learn to distinguish dozens of different leaves to eat without effort or instruction by tagging along with their mothers.
Obviously, we're learning a lot more than just how to find food. Your family's reactions to the world wired you to know what is good and bad for survival by turning your happy chemicals on and off, as well as your icky chemicals. You saw what pleased and pained those around you, and you learned those ways of being pleased and pained.
Now, you are a sophisticated individual who is nothing like your family, of course. That’s because the brain creates another layer of neural circuits during the teen years. Of course you are an erudite adult who is not ruled by teen schemas. But puberty floods the brain with hormones that facilitate new connections between neurons. This makes evolutionary sense because our ancestors often moved to new tribes at puberty. Our animal ancestors moved to new troops at puberty, which prevented in-breeding. In new surroundings, you need to store new survival information, and natural selection created a brain that's ready to do the job.
When you were in puberty, berries are not the reward that got your attention. Social rewards triggered your circuits. When you got the respect of your peers, your brain released serotonin, which fused a pathway for getting more social respect in the future. When you felt the security of social trust, your brain released oxytocin, which connected neurons that help you get more social trust in the future. When you encounter new experiences in the world, your brain channels them through the pathways you already created because that's the most efficient way to make sense of the information overload.
Your teen experiences were stored on top of earlier social experience. You started storing social experience the moment you were born. A gazelle can run with the herd the day after it's born, but a human infant's main survival skill is the ability to seek social support. When you were a baby, you built social bonds as if your life depended on it, because it did. When you enjoyed a moment of social trust, your brain released oxytocin and it wired you to seek social trust in that way in the future. When you enjoyed a moment of social dominance, your brain released serotonin and prepared you to seek social dominance in that way again.
Each life experience is unique. When I was young, my mother was very volatile. I learned that she might explode with rage if I asked for something. So instead of learning to survive by trusting her to do things for me, I developed other survival circuits. When my husband was young, he played games with his father and noticed that his father had to win. My husband learned to let his father dominate. Instead of seeking survival by trying to win, he wired himself to seek social dominance in other ways.
Every early experience has its quirks. Your family may have felt joy in response to things that were bad for survival. Your family may have felt pain in response to things that could have been viewed more positively. You were just a little mass of neurons building connections to survive.
In recent years it has become fashionable to insist that the brain can change at any age. This neuroplasticity fad is being spread by people who are selling something. They are not telling the whole story. While it's true that you can always add new leaves to your neural trees, the brain builds on the limbs it has already established. Evolution makes it clear why early wiring matters.
A species can only survive if each child that is born develops the capacity to survive when its mother is gone. Some species manage to do this with very few neurons. Others use a lot. Extra neurons actually hurt survival prospects because they need so much glucose, oxygen and warmth to stay alive. They only help if a creature really gets its money's worth out of them. Neurons have survival value when you connect them up in ways that give you a survival advantage.
That takes time, which explains why the length of an animal's childhood correlates strongly with the size of its cortex. Reptiles leave their offspring at birth, while apes stay with their mothers for 7-10 years. Learning from your family seems like the engine of evolution. A small-brained creature is born adapted to a particular niche, and it dies outside that niche. A big-brained creature learns about the niche it’s born into instead of just relying on the instructions it was born with. And it can learn a second niche during puberty.
Humans have more neurons at birth than in adulthood. That’s because the brain “prunes” itself at age two. Neurons that have not been used atrophy, which leaves room to build onto the neurons you already started connecting. At age two, you started relying on what you already knew rather than just taking in everything unselectively. By the time you were seven, your years of peak neuroplasticity were over. You started building new branches on the neural trees you had already established. It’s important to see the survival value in this. A child under seven is easy to lie to because they take in everything uncritically. After seven, a child starts relying on the neural circuitry it has already built. It evaluates new inputs in the context of what it already “knows.”
As much as we like the idea of “change,” there’s no survival value in re-learning everything each day. Your brain accumulates experience for the purpose of using it, not for the purpose of throwing it out the next day.
This can be painful for people with bad childhood memories. But it’s better to know this than to believe something is wrong with you for having been shaped by your early experience. If you don’t know how your brain got shaped, you will blame your neurochemical frustrations on your spouse, your boss, your bank and your government. And that will seem perfectly normal to you because everyone else is doing it. We are the first generation to benefit from deep knowledge of our mental equipment. We will pass this knowledge on to the next generation and they will benefit from it.
My book Meet Your Happy Chemicals explains in everyday language how you built your neural network, and how you can tinker with it to trigger more happy chemicals.