Accumulating over minutes and months and decades, the innumerable brain changes tally up to what we call you.
Or at least the you right now. Yesterday you were marginally different. And tomorrow you’ll be someone else again.
LIFE’S OTHER SECRET
In 1953, Francis Crick burst into the Eagle and Child pub. He announced to the startled swillers that he and James Watson had just discovered the secret of life: they had deciphered the double-helical structure of DNA. It was one of the great pub-crashing moments of science.
But it turns out that Crick and Watson had discovered only half the secret. The other half you won’t find written in a sequence of DNA base pairs, and you won’t find it written in a textbook. Not now, not ever.
Because the other half is all around you. It is every bit of experience you have with the world: the textures and tastes, the caresses and car accidents, the languages and love stories.4
To appreciate this, imagine you were born thirty thousand years ago. You have exactly your same DNA, but you slide out of the womb and open your eyes onto a different time period. What would you be like? Would you relish dancing in pelts around the fire while marveling at stars? Would you bellow from a treetop to warn of approaching saber-toothed tigers? Would you be anxious about sleeping outdoors when rain clouds bloomed overhead?
Whatever you think you’d be like, you’re wrong. It’s a trick question.
Because you wouldn’t be you. Not even vaguely. This caveman with identical DNA might look a bit like you, as a result of having the same genomic recipe book. But the caveman wouldn’t think like you. Nor would the caveman strategize, imagine, love, or simulate the past and future quite as you do.
Why? Because the caveman’s experiences are different from yours. Although DNA is a part of the story of your life, it is only a small part. The rest of the story involves the rich details of your experiences and your environment, all of which sculpt the vast, microscopic tapestry of your brain cells and their connections. What we think of as you is a vessel of experience into which is poured a small sample of space and time. You imbibe your local culture and technology through your senses. Who you are owes as much to your surroundings as it does to the DNA inside you.
Contrast this story with a Komodo dragon born today and a Komodo dragon born thirty thousand years ago. Presumably it would be more difficult to tell them apart by any measure of their behavior.
What’s the difference?
Komodo dragons come to the table with a brain that unpacks to approximately the same outcome each time. The skills on their résumé are mostly hardwired (eat! mate! swim!), and these allow them to fill a stable niche in the ecosystem. But they’re inflexible workers. If they were airlifted from their home in southeastern Indonesia and relocated to snowy Canada, there would soon be no more Komodo dragons.
In contrast, humans thrive in ecologies around the globe, and soon enough we’ll be off the globe. What’s the trick? It’s not that we’re tougher, more robust, or more rugged than other creatures: along any of these measures, we lose to almost every other animal. Instead, it’s that we drop into the world with a brain that’s largely incomplete. As a result, we have a uniquely long period of helplessness in our infancy. But that cost pays off, because our brains invite the world to shape them—and this is how we thirstily absorb our local languages, cultures, fashions, politics, religions, and moralities.
Dropping into the world with a half-baked brain has proven a winning strategy for humans. We have outcompeted every species on the planet: covering the landmass, conquering the seas, and bounding onto the moon. We have tripled our life spans. We compose symphonies, erect skyscrapers, and measure with ever-increasing precision the details of our own brains. None of those enterprises were genetically encoded.
At least they weren’t encoded directly. Instead, our genetics bring about a simple principle: don’t build inflexible hardware; build a system that adapts to the world around it. Our DNA is not a fixed schematic for building an organism; rather, it sets up a dynamic system that continually rewrites its circuitry to reflect the world around it and to optimize its efficacy within it.
Think about the way a schoolchild will look at a globe of the earth and assume there is something fundamental and unchanging about the country borders. In contrast, a professional historian understands that country borders are functions of happenstance and that our story could have been run with slight variations: a would-be king dies in infancy, or a corn pestilence is avoided, or a warship sinks and a battle tips the other way. Small changes would cascade to yield different maps of the world.
And so it goes with the brain. Although a traditional textbook drawing suggests that neurons in the brain are happily packed next to one another like jelly beans in a jar, don’t let the cartoon fool you: neurons are locked in competition for survival. Just like neighboring nations, neurons stake out their territories and chronically defend them. They fight for territory and survival at every level of the system: each neuron and each connection between neurons fights for resources. As the border wars rage through the lifetime of a brain, maps are redrawn in such a way that the experiences and goals of a person are always reflected in the brain’s structure. If an accountant drops her career to become a pianist, the neural territory devoted to her fingers will expand; if she becomes a microscopist, her visual cortex will develop higher resolution for the small details she seeks; if she becomes a perfumer, her brain regions assigned to smell will enlarge.
It is only from a dispassionate distance that the brain gives the illusion of a globe with predestined and definitive borders.
The brain distributes its resources according to what’s important, and it does so by implementing do-or-die competition among all the parts that make it up. This basic principle will illuminate several questions we’ll encounter shortly: Why do you sometimes feel as though your cell phone just buzzed in your pocket, only to discover it’s on the table? Why does the Austrian-born actor Arnold Schwarzenegger have a thick accent when he speaks American English, while the Ukrainian-born actress Mila Kunis has none? Why is a child with autistic savant syndrome able to solve a Rubik’s Cube in forty-nine seconds but unable to hold a normal conversation with a peer? Can humans leverage technology to build new senses, thus gaining a direct perception of infrared light, global weather patterns, or the stock market?
IF YOU’RE MISSING THE TOOL, CREATE IT
At the end of 1945, Tokyo found itself in a bind. Through the period that spanned the Russo-Japanese War and two world wars, Tokyo had devoted forty years of intellectual resources to military thinking. This had equipped the nation with talents best suited for only one thing: more warfare. But atomic bombs and the fatigue of combat had abated its appetite for conquest in Asia and the Pacific. War was over. The world had changed, and the Japanese nation was going to have to change with it.
But change invited a difficult question: What would they do with their vast numbers of military engineers who, since the dawn of the century, had been trained to produce better weaponry? These engineers simply didn’t mesh with Japan’s newly discovered desire for tranquility.
Or so it seemed. But over the next few years, Tokyo shifted its social and economic landscape by redeploying its engineers toward new assignments. Thousands were tasked with building the high-speed bullet train known as the Shinkansen.5 Those who had previously designed aerodynamic navy aircraft now crafted streamlined railcars. Those who had worked on the Mitsubishi Zero fighter plane now devised wheels, axles, and railing to ensure the bullet train could operate safely at high speeds.
Tokyo
