What’s the difference between a male friend and a female one?

We’re in the middle of a pandemic which Robin Dunbar says has created a “plague of loneliness”: an enforced isolation that reminds us that we need other people; we need our friends. In fact, Dunbar says that what has really surprised researchers over the last decade is just how dramatic the effects of having friendships are – for our health, our wellbeing, and even our longevity. We do not cope well with isolation and friends are good for us.

So what exactly is a friend, and how many should we have? Dunbar defines a friend as someone you wouldn’t feel embarrassed about borrowing a tenner from. “It’s the expectation that they would go ‘yeah here you are’ without a hassle,” he says. “Acquaintances would be thinking ‘well, are you going to pay me back?’ or ‘I’ll do it if you do something for me.’ It’s much more explicitly reciprocal whereas real friends will go ‘Oh God, not again Jim, but here you go’.” Dunbar does emphasise, however, that there are limits – if a friend keeps on asking, or abusing the privilege, it’s likely the friendship will reach breaking point.

Dunbar says there are also limits to the number of friends we can have – in fact, he’s worked out precisely how many and it’s become known as Dunbar’s Number. What he found is that we have circles of friends beginning with an inner circle of five intimate friends, which can include a partner or a relative, then a wider circle with around 15 close but less intimate friends, and so on, in a series of bigger and bigger circles. The innermost circle corresponds to people we contact at least once a week, the next circle is people we would contact at least once a month, then every six months, and so on, out to the outer circle of people we would make an effort to contact once a year and feel least close to. The total limit on the number of people in the network is 150 and this holds remarkably true in all kinds of cultures and societies, online and offline.

What is the basis of a good friendship?

Dunbar says that we all, unconsciously, use the same broad criteria for judging whether someone is a good candidate to become a friend and he calls them the Seven Pillars of Friendship. They are: having the same language or dialect, growing up in the same location, having the same educational and career experiences, having the same hobbies and interests, having the same world view, having the same sense of humour, and finally, having the same musical tastes. You won’t necessarily share all of the pillars with all of your friends, but the more of the boxes you tick with someone, the more time you’ll be prepared to invest in them; you tend to gravitate towards people with whom you have more in common. You tend to like people who are most like you.

Dunbar says that, much to his surprise, a similar taste in music is particularly important. “That completely left-fielded us,” he says. “It wasn’t even in our original list of things you might have in common with a friend because we just didn’t even consider it. We’re not sure what’s going on. We were astonished how strong it came out as a factor – we still have no idea why it should be so strong except that music is a central bonding mechanism for small communities – think of a ceilidh at a wedding, there is nothing like that to turn a bunch of complete strangers into people who seem to have known each other since birth.”

What do you need to do to make a new friend (and keep them)?

Making friends, and keeping them, requires a great deal of effort and time, says Dunbar. The research suggests that it takes around 45 hours spent in someone’s company for them to progress from being an acquaintance to a friend and to move from being a casual friend to a meaningful friend requires another 50 hours over three months and best friends takes another 100 hours. In effect, he says, to make it into the most intimate category of friendship requires something close to an average of two hours a day, day after day, for a considerable time. Friendship does not come cheap.

“Two hours a day sounds like a lot of time,” says Dunbar, “but you have to put that into the context that a decent social interaction actually occupies about half an hour on average. Some may be all evening. It’s doing all the kind of things like telling jokes, singing, all these kind of things that are very time-consuming - you can’t sort of just nip in, do it for two minutes, and then nip out again, you have to build up to it, otherwise it’s not right and it doesn’t work. Bearing that in mind, if each interaction minimally is half an hour, you’re only going to see five people a day and you have to keep doing that – you can’t just do it once and then it’s hunky dory from then on. It’s like vaccination - you have to keep reinforcing it over and over again for that relationship to provide you with what you need.”

What this means is that friendship can be hard-work and time-consuming and it’s this that puts a limit on the number of meaningful friends we can have. In effect, says Dunbar, we decide who is important to us and allocate time to them in ways that reflect their value to us. Sixty per cent of our total social effort is devoted to just 15 people. The remaining 135 people in our social network have to make do with what’s left over.

Dunbar says the way we live now has also made the process of keeping and maintaining friends harder than it used to be. “What’s happened really only in the last 50 years or so since the rise of cheap transport, you have people being able to move around a lot more and the consequence of that is your extended family stays the same - they don’t change – but your friends consist of little clusters of people you’ve picked up on the way through life. School, or university, first job, the year in Thailand, etc, etc. and these little groups don’t know eachother and they don’t know your family. That creates very fragmented friendship networks which means they’re not nearly as supportive and because they’re scattered, it’s much harder work. You just can’t walk round the corner and knock on Jimmy’s door and say let’s go for a beer.”

What is the difference between male and female friendships?

Dunbar says the difference between male and female friendships has, in many ways, been the most surprising feature of his 25 years of research into the subject. He believes that the two sexes effectively live in two different social worlds and approach relationships in very different ways.

For a start, as a general rule, we tend to prefer friends of our own sex – around 70% of women’s social networks consist of women and around 70% of men’s consist of men. Male friendships tend to be more casual and women’s closer and more intense. Women also tend to have much higher expectations of friendships than men do.

“If you want a simple summary,” says Dunbar, “it’s that women’s friendships are very intense and focused and very dyadic – if one of them lets you down, it’s a crisis. Whereas the blokes – friendships are much more casual – it’s not to say that they don’t have the same elements, they’re just much more casual. If somebody disappears to the rigs or something for six months, it’s just ‘ok, we’ll find somebody else to go drinking with’ and that’s perfectly ok. Boys’ friendships tend not to break up catastrophically.”

These sex differences hold remarkably true right through the generations, says Dunbar. “They hardly change, it’s extraordinary. I think a lot of it has to do with there’s a kind of riskiness because of the sexual element creeping in over the horizon between men and women.” But he says it’s also because the style of friendships can be very different between men and women – the conversation between a group of male friends is much more likely to be banterish and raucous, for example, whereas a group of female friends is likely to prefer something more intimate. “It goes back to the fact that it’s just easier for girls to talk to girls and boys to talk to boys,” he says. “The nature and style of the conversations is very different.”

Are online friends the same as offline ones?

On Facebook, we can have hundreds of friends, thousands even, certainly more than the 150 limit Dunbar suggests, but he says we need to ask an important question: how many of your online friends are meaningful friends? As it happens, the research shows most people have been 50 and 300 friends on Facebook, with an average of 169, which is pretty close to Dunbar’s Number.

Dunbar also believes that online friendships cannot replicate or replace real-life ones because all friendships, he says, depend ultimately on seeing people – and getting the boost we get from physical contact or closeness. Brain scans show that the touch of someone close to us – a hug, a kiss on the check, a supporting hand on the shoulder, or pat on the back - boosts endorphins and other activities we do with friends can have the same effect: laughing, singing, dancing, eating, and (you’ll be pleased to hear) drinking alcohol.

Dunbar calls it “virtual grooming”. “The nature of friendships is operating at two levels because we’re primates basically and this is how primates create their friendships,” he says. “It’s the underlying subconscious deep brain that is not directly accessible – the endorphin system. All the things we do in a social context, clapping on the shoulders and hugs and laughter, they all trigger the endorphin system in the most amazing way and that provides the sense of warmth and trust and bonhomie with the person you’re engaged with.” And try as you might, Facebook and Twitter and Zoom cannot replace it.

Why do some friendships end?

Most of us lose friends at some point, but then you probably didn’t need the research to tell you that one. Dunbar says a turnover in friends is normal – in fact, his data suggests that, on average, you can expect to have one terminal relationship breakdown every 2 to 3 years, roughly equivalent to losing 30 friends across your adult life.

Partly, he says, we lose friends because some friends are just a matter of convenience – someone to party with or go on day trips with who will do for the moment until someone better comes along. And if a friendship does break down, it tends to happen in one of two ways – by gradually dying out or by cataclysmic collapse (it’s more likely to be the first).

Dunbar says there are six key rules to maintaining a stable relationship and breaking several or all of them is likely to end the friendship. They are: standing up for the friend in their absence, sharing important news with the friend, providing emotional support when it’s needed, trusting and confiding in each other, volunteering help when it is required, and making an effort to make the other person happy. Breaking any of these rules is likely to weaken the relationship, he says, and breaking many of them is likely to lead to the end of the friendship.

“The baseline is that the moment you stop seeing somebody at the rate appropriate to where they sit in your social network, the quality of that relationship starts slowly to fade,” he says. “Our data suggests you probably won’t pick anything up in the first three months or so - the digital world does a good imitation of a sticking plaster in this context – it slows down the rate of decay a little bit but it doesn’t solve the problem. It probably takes six months of not seeing somebody before it starts to show a big shift in the quality of that relationship and it probably takes in the order of 3-5 years of not seeing somebody for them to slide from being a friend to an acquaintance.”

How has the pandemic affected friendships?

Dunbar says one of the ironies of a pandemic that has isolated us from friends is that the research shows being with your friends is good for your immune system. The endorphins triggered by the presence of friends tunes the immune response and gives us enhanced resistance to bugs – in other words, just when our immune systems could do with the boost that our friends provide, we can’t see them.

Dunbar believes the enforced isolation will be particularly hard for older people. Persistent loneliness and lack of friends is correlated with an increased risk of Alzheimer’s, depression and dementia, and older people tend to have smaller friendship networks anyway.

“Your social network increases in size from zero at birth, hits a peak of 250 when you’re 18-25-years-old, then settles down by the mid-30s to about 150, after it stays very stable at that until you reach 65 and then it starts to decline,” says Dunbar. “If you live long enough, you end up back at zero again, but that’s because you can’t go anywhere. If you’re 20something and your friends disappear, you know where to go to replace them and the problem for the elderly is it’s much more difficult for them to replace friends because they no longer have the energy or the motivation to do it and secondly they don’t know where to go anymore. You can’t go to the Glasgow clubs and stick your nose in. You wouldn’t know where to start a conversation.”

Dunbar is particularly concerned about the effect of the pandemic on people’s physical and mental health. “If a prolonged period of lockdown causes the elderly’s social network to contract faster than it would have done, that will increase their risk of things like Alzheimer’s or other diseases,” he says. But he says the upside is that people will be even more keen to see their friends when it’s all over. “One of the things we’ll see is exactly what we saw after the Spanish Flu in 1920 – everyone was just as terrified then, far worse than now, they were trying to avoid contact, but as soon as it all cleared through the system, what happened after that? The Roaring 20s. Everybody went out and had a big party!”

Friends: Understanding the Power of our Most Important Relationships by Robin Dunbar is published by Little, Brown at £18.99