A nineteen-year-old Harvard student is standing perfectly still while a doctor measures the shape of his face. He’s one of a few hundred boys signed up to be tracked for the rest of their lives – some are the university’s golden boys – privileged, athletic and very obviously destined for big things.

The rest come from the poorest streets in Boston.

Over the next sixty years researchers will collect every data point under the sun, from their blood pressure to bank balances, in one of the longest and most detailed studies of humans ever run.

If the secret to a long and healthy life can be measured, it’s sitting somewhere in among these files.

As the men start to grow old, the researchers finally turn to the question they’ve spent six decades waiting to answer.

What separates the ones who age well from the ones who don’t?

Somewhere between the blood tests and brain scans, one thing starts predicting future health even better than cholesterol.

The quality of their relationships.

Blueprints

From the outside, the human body has changed a lot over time. We’re taller than our ancestors, we’ve got longer legs, our skeletons are lighter, even our faces have softened.

But underneath these visible upgrades the brain remains largely the same organ it was tens of thousands of years ago.

Over millions of years, the nervous system learned what kind of world it lived in and wired itself to win – gradually, this became the blueprint it needed to work and feel its best.

Our ancestors lived in close rhythm with the natural world around them. Light arrived in the morning and faded at night, darkness signalled sleep, and movement was built into the basic structure of the day.

But most importantly, proper face-to-face social connection was deeply baked into everyday life.

Evolution built a body that expects to spend long stretches of time with people it trusts.

The modern world handed it a calendar invite instead.