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.

And I’ll admit that these social interactions I describe were an unexpected benefit. But the purpose of P.U. was never to turn programmers into artists or artists into belly dancers. Instead, it was to send a signal about how important it is for every one of us to keep learning new things. That, too, is a key part of remaining flexible: keeping our brains nimble by pushing ourselves to try things we haven’t tried before. That’s what P.U. lets our people do, and I believe it makes us stronger.

Learning in community helps us see how our own ideas are shifting over time. Hopefully we develop and change with time, applying life experience to our way of seeing the world. It seems a sign of immaturity to hold fast to one position regardless of new information.

If we accept the wisdom—and more recently the scientific evidence—that our relationships really are among our most valuable tools for sustaining health and happiness, then choosing to invest time and energy in them becomes vitally important. And an investment in our social fitness isn’t only an investment in our lives as they are now. It is an investment that will affect everything about how we live in the future.

Here is where Emmy Werner’s research, our own Harvard Study research, and many other pieces of research from across cultures and populations converge to show that a critical link between childhood experience and positive adult social connections is our ability to process

emotions.

It is from our relationships as children—especially our relationships with our family—that we first learn what to expect from others. This is when we begin to develop the emotional habits, so to speak, that will be with us for the rest of our lives. These habits often define the way we connect to others and our ability to engage others in mutually supportive ways.

A crucial point here is that our ability to process emotions is malleable. In fact, managing emotions is one of the things we actually get better at as we grow old. And there is strong evidence that we don’t have to wait until late in our lives for this to happen. With the right guidance and some practice, we can learn to be better at managing our feelings at any age.