The laws of friendship: do birds of a feather flock together?

Friends are the family you can choose, as the saying goes - and it's very true. But why and how do you choose them, the completely voluntary second family? In other words, according to what criteria? When I look around me, I can't recognise a common thread. Perhaps a shared consensus of values, but that's about it. Because there are no great similarities or even similar life plans, neither among those I have known forever nor among those who have joined over the years. And yet - or perhaps because of this - we enrich each other greatly.

Friendship is suddenly there - even if it can take time to get to know each other. It's the pleasant feeling of being with someone who suits you and understands you. At best, this attraction lasts a lifetime.That's why I find the new findings from friendship research all the more interesting. I'm currently reading a book by Steve Stiehler, professor in the Department of Social Work at the University of Applied Sciences St. Gallen. In it, he addresses a blind spot in his discipline: bromance. His conclusion: "Overall, it is clear that friends act as important supporters and unique resources for men in order to ward off psychosocially threatening situations. Existing male friendships increase the ability to act, as friendly support increases self-esteem and conveys recognition". Bromance is not as superficial and often chummy as portrayed in TV series or Hollywood films.

Social homophily: Birds of a feather flock together

Today I would like to look at the "why", the motives and motivations behind long-term friendships. "Birds of a feather flock together" is an easy saying, simply because it sounds understandable. Good friends are often of a similar age, share common interests or have a similar social background. Science calls this "social homophily". Sociogenetics goes one step further and believes that friends are not only socially affine. In a long-term study, a team of scientists from Stanford University found that friends are apparently also genetically similar - in any case, significantly more so than randomly selected pairs of people of more or less the same age.

Friendship: Perceived similarities and other conveniences

The French psychoanalyst Saverio Tomasella, author of the book "Ces amitiés qui nous transforment" ("Friendships that change us"), svehemently disagrees. He also casts doubt on an old US study among students, which came to the conclusion that birds of a feather flock together. During training, we do tend to get closer to people who are similar to us because they help us to achieve our goals. "However, I have realised that our best friends are very different from ourselves. They may practise a different religion, have different political ideas and even come from a different social milieu," says the author. Do similar interests, character traits and even genes only play a minor role after all?

Friendship research now knows this: Close friends are often not as similar as people think. They just perceive themselves as similar. Psychology professor Jaap Denissen from Humboldt University Berlin has observed the initiation of friendships in a study. The results show that Those who judge other people - compared to themselves - to be similarly accurate, open, agreeable or anxious are more likely to befriend them. "However, this perception often does not correspond with reality," says Denissen, "but this does not harm the quality of the friendship."

However, he did notice a certain calculation: The warmth and extroversion that someone radiates also make them attractive as a friend - because such people are trusted to provide comfort in dark hours.

But back to the (supposedly) same wavelength: American psychologist Paul Eastwick from the University of Texas also says: "If we have the feeling that someone is similar to us, then the likelihood that we will also like them increases. But if we put two people together who are actually similar, do they also like each other? The effects that we can observe are extremely weak." His study on the topic proves this: (perceived) similarity is more of a proof of attraction than a prerequisite for it.

Time and closeness: how we become friends

What other criteria are there? The "mere-exposure" effect is likely to play a major role. This psychological phenomenon states that repeated perception leads to a positive evaluation of something over time - and this also applies to friendships. Our brain can process what we know well more easily and rewards us for it. In other words, the more often you meet people or interact with them, the more likely they are to become your friends. This aspect is crucial because you only consider people who you think know you particularly well to be true friends.

Patial proximity makes it possible to meet each other often and get to know each other much more quickly. How much time does it take for real intimacy? This is what American researcher and Nobel Prize winner Jeffrey Hall found out in several studies on the question of how many hours you need to spend together to get really close. The results, in a nutshell: it takes at least 50 hours together to go from acquaintance to friend, a further 90 hours are needed to move into the "good friend" category and a whole 200 hours together to become "best friends".

So if you are looking for new BFFs (best friends forever), you should spend a lot of time with them and be open with them. And if you already have some, you should cultivate this relationship - even if your job or family take up a lot of your time. Because as the saying goes: "Life is like a train journey. Many people get on, many get off. But only a few will travel with you to your destination."

In part 2 of our friendship series, you will find out why your best friend makes you healthier - and can even extend your life.