Relationships are a Limited Numbers Game

Relationships are a Limited Numbers Game

Yesterday I was staring at the 1,400 or so connections on one of my social media accounts. It got me thinking about the impacts of being able to so easily connect and stay linked to large numbers of people using technology. It’s long been understood that larger and effective social groups let us gain evolutionary advantages from the richer cultures. The relationships and social networks we form may be the most significant factor affecting happiness, wellbeing and even mortality. Well-formed relationships let us live longer, healthier and happier lives. Does this mean that technology is letting us soar to new heights of social connectivity? 

Unlikely, because there is a catch, and it relates to a theory known as “Dunbar’s number”. Robin Dunbar, a insightful and impactful anthropologist, believed that there is an upper limit to the number of meaningful relationships that we can form, topping out at an average of 150 people. Dunbar’s theory starts with the observation that primates (a genus which includes humans) have unusually large brains for their body size. 

Our large brains could be owed to ecological reasons, like helping us forage more effectively for varied food, or for social reasons. Once we show that brain size doesn’t corrolate to effectiveness in food gathering, then we are left with the correlation between brain size and size of our social groups. 

An analysis of primate social groups, as well as human societies, suggests that our social fabric is formed into layers. Our first and closest layer starts with just five people. Dunbar theorises that each social layer holds three times the number of relationships than the layer preceeding it. The layers progress from 5, through 15 to 50, 150, 500 and 1500. The number of deeper relationships stops at about 150, with a varience from 100 to 200. The varience accounts for the differences between naturally introverted and extraverted people. 

A visual depiction of Dunbar’s number theory (image inspired by    brainpickings.org  )

A visual depiction of Dunbar’s number theory (image inspired by brainpickings.org)

Crucially, our interactions with people in different layers is not equal. We feel less close to and naturally invest less time and effort in those people in our outer social layers. Friendships are not free. Creating and maintaining friendships costs time, effort, attention and emotion. As new people are added to our inner circles, older, less intimate relationships on the outer layers are dropped or changed. For this reason we are inclined to invest heavily in those closest to us. We tend to invest nearly 40% of our socially-oriented efforts in the five most important people to us. We then dedicate a further 20% to the next ten closest people. This is a cumulative total of 60% committed to emotional connections for just fifteen people. 

Beyond our closest 150 relationships, we begin to struggle. We have less time to dedicate to individuals and less capacity to remember the state of our relationship. Unlike other primates, we also have interesting physical limits around who touches us and how. In the physical world we’ve hacked these limitations through the use of shared activities such as talking, singing and dancing. These allow us to connect, albeit less intimately, with larger numbers of people we don’t know well. 

You might be forgiven for thinking that these insights only apply to primates in the wild or primitive human societies. You would be wrong. More recent research suggests that these same constraints can be seen in patterns of our calls, chats and our social media groups. Think about it for a moment. Meaningful social groups are defined by a trust that the person on the other side of the relationship will act prosocially, just as they are trusting we will do the same. This trust is built by consistent shared experiences, information, emotion and favours. The more people we attempt to add to our group, then the less time we can spend on any of them. The quality of our social fabric then decays. 

So what does this mean? Well, it means it doesn’t matter that Facebook lets us have 5,000 friends because we can only form close relationships with a few of them. It also doesn’t matter that our mobile phones seamlessly allow us to contact the thousands of people in our contact list. A review of real phone contact data suggests that people focus their time on a limited number of contacts, just as they did before the introduction of such technology. This points to something very deep. Fundamentally, our psychology did not evolve to handle a number of unlimited interactions simultaneously, despite technologies that allow us to do so.

The problem is that technology doesn’t just allow us to interact with the hundreds or thousands of people in our online social networks, it pushes us to attempt to do so.  The digital platforms we use are built to encourage us to grow our networks and to do our best to maintain them. Emails show up in our inbox saying things like, “Your friends haven’t heard from you for a while. Share something new.” Our technologies are being designed to encourage us to grow our networks, to seemingly unsustainable levels. After all, there is a deeper incentive here, more people in a relationship platform typically points to larger valuations, stock offerings, potential to sell advertising or usable  intelligence about the people and their connections. 

These are poor design choices. I am not saying that all digital means of communication are destructive; quite the opposite, because in many cases digital methods of communication can allow widely seperated people to connect deeply and consistently, as long as it is a small set. What I am saying is that it is a numbers game. The more you have, the lower quality the aggregate becomes. Try to dedicate time and effort to hundreds of your social contacts, and you might soon find the intimacy of even your closest relationships fading.

In a world where loneliness is fast becoming a genuine social and emotional epidemic, it makes me think twice about how I choose to invest my own time, how I interact with modern platforms and what part they play in my life. It seems to challenge the orthodoxy of trying to use relationship platforms to gain more social connections. A better solution seems to build or use whatever you can to form smaller groups with deeper relationships.


“Reclaiming Friendship: A Visual Taxonomy of Platonic Relationships to Counter the Commodification of the Word “Friend”; Maria Popova: www.brainpickings.org/2016/08/16/friendship/.

Dunbar, R.I.M. (2018) The anatomy of friendship, Trends in Cognitive Sciences, January 2018, Vol. 22, No. 1 https://doi.org/10.1016/j.tics.2017.10.004.

Dunbar, R.I.M. (1993), Neocortex size as a constraint on group size in primates, Journal of Human Evolution, Vol. 20, p. 469 - 493

Carron, Mac P. Kaski, K. Dunbar, R. (2016) Calling Dunbar’s numbers, Social Networks 47 (2016) 151–155.

Miritello, Giovanna. Moro, Esteban. Laraa, Rubén. Martínez-Lópeza, Rocío. Belchambera, John. Robertse, Sam G.B. Dunbar, Robin I.M. (2013) Time as a limited resoruce: Communication strategy in mobile phone networks, Social Networks Vol. 35, p. 89-95.

Group of Photo by Dane Deaner on Unsplash.

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