Friendship by the Numbers

Source: Adobe Stock Images

Let’s start off like this: 

Make a list of the top fifteen people in your life, ranked by frequency and intimacy of your contact with them. 

I’ll wait.


Ok, now draw a circle around the top 1.5.

(Yes, I realize it will chop someone dear to you in half. My apologies. It is just a list though, relax.)

These one and a half people likely share a dwelling with you (or have in the past) and probably often see you at your very worst, both physically and emotionally speaking. You don’t put on a mask for them.

They are likely your spouse, your mother, your child, your best friend in the whole world. You probably talk or text with them on a daily basis.

Next draw a second circle that encompasses the top five people in your life — including the original 1.5. These are your intimate life partners. The people who probably can tell just by looking at you when you are stressed. The people you call first when bad news strikes. The people who can most easily make you laugh.

Your “Top Five” are your Scooby Gang

Source: c/o Mutant Enemy Productions

These people you are likely to contact at least weekly in some form. If we were to measure how much of your social time and effort you spend on other people (and yes psychologists do such things), you would probably be spending a full 40% of your “social capital” on just these five people.

The third circle encompasses the entire fifteen. These are your very good friends — you care for them deeply, you know you can rely on them if you were to suddenly need support, and you are probably are in contact at least monthly. These are what some people call “the sympathy circle,” the people whose hearts would rend wide open were you to suddenly die. These fifteen people comprise about 60% of your social capital, and may be the basis of a “childcare exchange” network. In other words, if you chose to have kids, these are the people you could wrangle to babysit sometimes.

We could expand the circles even more — the next thirty-five friends you would definitely sidle up to in a bar uninvited and are likely on your Christmas card list, but you may not talk to them more than once or twice a year and they probably aren’t privy to your innermost fears and desires.

Source: Adobe Stock Images

We’d hit the limit around 150, which based on the best anthropological evidence is the maximum size of a functional social network for human beings. That isn’t to say that you can’t recognize or be familiar with more than one hundred and fifty other human beings, but rather that you wouldn’t be able to maintain relationships in which you contribute your physical and emotional time to the well-being of more than that number.

This number – 150 – is known as Dunbar’s number, for anthropologist and evolutionary psychologist Robin Dunbar.

Dunbar recently released a wonderful article in a journal Trends in Cognitive Science (or, affectionately to those who know it well, TiCS) called The Anatomy of Friendship. He reviewed multiple types of literature — anthropological, comparative (cross-species), psychological, neurobiological — to share how friendship works. On average, of course – he also shares that we each have a social fingerprint, our own peculiarities for how frequently we prefer social contact and how exactly we divvy up our social capital among our fellow life travelers.

Disruptions and Variations

A few more fascinating tidbits from Dunbar’s research…

When we fall in love, our new beloved zooms right up to the top five, often with catastrophic consequences for some of our deepest relationships. On average, during the infatuation period we lose one close family member and one close friend from this inner circle, temporarily shifting it to four instead of five and greatly changing the composition of our inner circle.

These numbers and proportions remain remarkably stable over time, even as membership shifts. If a close friendship dissolves, we tend to slide a new person into their slot, expending strikingly similar amounts of time and emotion on the new person.

Source: Adobe Stock Images

“Kin-keepers” are individual people who tend to shoulder the responsibility for keeping all of the family in close contact with each other — scheduling reunions, nudging people who have fallen out of touch.

While oxytocin tends to get all the press, Dunbar’s review of the evidence suggest that endorphins released during “social grooming” (laughter, singing, dancing, emotional storytelling) play a much greater role in bonding.

Part of friendship is the act of mentalising, or mentally envisioning the landscape of another’s mind. This process is extraordinarily cognitively taxing, and as such, intimate conversations seem to be capped at about four people before they break down and form smaller conversational groups. One exception is that if the conversation involves speculating about an absent person’s mental state (e.g., gossiping), then the cap is three — which is also a ratio that Shakespeare’s plays respect.

And finally, analyses of “reciprocated posting” on Facebook (I post a meme on your Timeline, a few days later you tag me in a Throwback-Thursday post) yields the same layering and numerical limits as all of this face-to-face research.

The internet isn’t changing us that much. Yet.


Follow along the writing of my new book Hivemind: The Perils and Promise of Our Collective Social Selves here on Instagram.


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