A phone call on a bad day
There are days when everything just goes wrong. A rejection, an argument, a message that pulls the ground out from under your feet. In the evening you sit on the sofa and reach for your phone. At the other end is someone who listens, asks questions and finally says: I'm coming over. The problem is not solved afterwards, but it feels smaller.
For many people, this is a given. For others, it is not. They scroll through their contacts and find no one they would call at a moment like this. The evening is the same, and so is the trouble. And yet their body experiences it completely differently.
This difference has consequences. A large analysis of 148 studies with over 300,000 people came to a remarkable conclusion: those who had good social relationships had a roughly 50 percent higher likelihood of survival. The researchers rated this effect as comparable to that of smoking, around 15 cigarettes a day. That puts relationships among the strongest influences on health and lifespan of all.
What does this have to do with your biological age? Your chronological age counts the years since you were born. Your biological age, on the other hand, describes the actual condition of your body, for example how much permanent tension it is under and how well it recovers from it. But how can a person at the other end of the line change something in your body?
The sentry: How your body reacts when support is missing
Picture a sentry sitting by the campfire at night. As long as others are around, someone eventually takes over and he can sleep. If no one relieves him, he stays awake all night, tense, alert to every sound. He can manage one night like that. Not weeks and months.
Your body carries a very old programme that works exactly like this. For our ancestors, being alone meant danger. Those who belonged to the group were protected. Those who were alone had to stay on guard themselves. This programme still runs today, even though there have long been no predators lurking around us.
If reliable people are missing, the stress system therefore never fully switches off. Stress hormones stay raised, sleep becomes lighter and more restless, and the immune system gears up for defence. Over time, this turns into a mild, persistent inflammation that you cannot feel but that puts a strain on blood vessels and cells. Accordingly, studies find raised inflammation markers in the blood more often in socially isolated people.
Reliable relationships, by contrast, work like relief for the sentry. The body can power down and recover in between. That is exactly what makes them so valuable for your biological age. One of the longest studies ever conducted shows how strong this effect can be over an entire lifetime.
What happens when you follow 724 people for a lifetime?
In 1938, researchers at Harvard University began an unusual project. They wanted to find out what allows people to age healthily and contentedly. To do so, they followed 268 Harvard students and 456 young people from poorer neighbourhoods in Boston. Over decades, the participants were interviewed, examined and visited in their family homes. The study is still running today, now with the children of the original participants.
Almost everything was collected: blood values, income, career paths, habits. When the participants were around 80, the researchers asked a simple question. What in midlife had best predicted who had grown old in good health?
The answer was not cholesterol. It was satisfaction with one's relationships. Those who were most satisfied in their relationships at 50 were the healthiest at 80. Robert Waldinger, who leads the study today, therefore describes close relationships as a protection that carries us through life's hardships and delays physical and mental decline.
This was particularly clear in difficult phases. Participants over 80 who were in a good relationship reported that their mood stayed good even on days with more severe pain.
Good relationships did not make them invulnerable. But they cushioned the strains that life brought with it.
Being alone is not the same as being lonely
Does that mean you need as many friends as possible? No. Research makes a clear distinction between social isolation, meaning few contacts, and loneliness, the feeling that something is missing. Both can be a burden, but they do not always occur together.
Some people spend a lot of time alone and feel fine about it, because they know someone will be there when it matters. Others are constantly surrounded by people and still feel alone. For the sentry, what counts is not the number of contacts in your phone, but the certainty that there is someone you can rely on.
The Harvard researchers also found that the number of relationships mattered less than their quality. Relationships that are full of conflict over long periods can even become a burden themselves. One or two people with whom you can be entirely yourself often do more than a large circle of friends.
That is good news, especially for introverts. You do not have to become the centre of every party. It is enough to look after the relationships that really matter to you.
How to strengthen your social network in everyday life
Relationships cannot be prescribed, but they can be nurtured. The Harvard researchers therefore speak of social fitness. As with physical fitness, the grand gesture counts for less than what happens regularly.
Often it is the small things: the voice message to an old friend, the fixed date for a run with a colleague, the family dinner that does not get cancelled just because the week was busy. If you want to meet new people, the easiest place to find them is where you see each other regularly, such as in a club, a choir, volunteering or a course. Shared activities create closeness almost incidentally.
One simple question can serve as your compass: who could you call if you were having a hard time? If one or two names come to mind, you have something very valuable that deserves looking after. If not, that is not a verdict on you, but a good starting point.
For your biological age, what counts is not how many people you know, but whether you can rely on some of them.
Where the BioAge test helps and where it doesn't
The BioAge test also asks about your social network. It can be a nudge to take an honest look at how supported you feel right now. But it is no more than a first check-in. It can in no way replace an open and honest conversation with someone you trust or with a professional.
Frequently asked questions about social relationships and biological age
How many friends do you need for a long life?
There is no fixed number. What matters is whether there are people you can rely on. Even one or two close relationships can make a noticeable difference.
Do family, partners and colleagues count too?
Yes. It does not matter where a relationship comes from, but whether it gives you support. A trusted colleague can be just as important as a sister or an old school friend.
Is it unhealthy to enjoy being alone?
No. Having time to yourself is not a problem as long as you do not feel cut off. It becomes a burden mainly when being alone is not voluntary or when no one comes to mind in difficult moments.
Do contacts via messaging apps and video calls count?
They can help maintain closeness, especially when people live far apart. But they are hard to substitute for meeting in person. A mix of both works best.
Can you still build new friendships as an adult?
Yes, it mainly takes time and repetition. One study estimates that an acquaintance becomes a casual friendship after around 50 hours spent together, and a close one after more than 200 hours. Meeting regularly in the same place, for example at a club or a course, makes this much easier.