← Back

Because of your genetic inheritance and the oddities of your early childhood environment, your brain’s wiring is utterly unique—no one has ever had a brain wired just like yours, and given the brain’s complexity, no one ever will. Some parts of your brain have tight thickets of synaptic connections, while other parts are far less dense. And when we examine your brain’s growth—when we count the new neurons and their connections—it turns out that you grow far more neurons and synaptic connections where you already have the most pre-existing neurons and synaptic connections. Perhaps this is caused by nature’s harshly efficient use-it-or-lose-it design, or perhaps, with so much pre-existing biological infrastructure supporting your densest synaptic regions, it is simply easier to forge new connections where you already have lots. Either way, we now know that, though every brain grows, each grows most where it’s already strongest. The arrow of brain development points toward specialization. As the neuroscientist Joseph LeDoux memorably described it, “Brain growth is like new buds on an existing branch, rather than new branches.