Why we need face to face contact


How many friends does a person need?

This is the question which evolutionary psychologist Professor Robin Dunbar at Oxford University has set out to address[i]. And the answer is consistent across time and space: 150.

The figure – known as Dunbar’s Number – is predicted by the Social Brain Hypothesis. This states that in primates, group size is related to brain size[ii]. Specifically, the neocortex: the outermost layer of our mammal brains most recently evolved.

Of course, we can ‘know’ many more people than this: acquaintances about whom we could say a few things (500 or so), or people whose face we just recognize because we met them once or twice (about 1,500).

Dunbar’s Number is not equally distributed – we reserve most time and ‘social capital’[iii] (trust, reciprocity, emotional bonds) for those we are closest to, typically spending 40% of our time with just three to five individuals[iv]. The diagram below illustrates these ‘orbits’ around a person. Where do people sit in your solar system?


Why 150? Because two factors limit our social circles.

Firstly, the brain power needed to ‘mentalise’ (understand others’ states of mind[v]) across complex chains of relationships. For example, person A believes that B thinks that C knows that D doesn’t trust E to be faithful to them (read that again starting at D if you need to!) Even the brightest people struggle to follow five orders of mentalising.[vi]

Secondly, time. We need to spend time with each other to make bonds and, crucially, to maintain them. While our family bonds need less maintenance than friendship bonds, even they will decay without contact.[vii]

For most of human history, we’ve had to be physically with someone to be in contact. Innovations like the telephone removed this need, and today some have argued that the technologies of the Internet will enable us to break Dunbar’s Number and expand our social circles indefinitely[viii]. One main way to do this is by communicating simultaneously with many people[ix], as Social Networking Sites (SNS) in particular allow.


However, this seems not to have occurred. Before SNS existed, Stanford academic Norman Nie found that people who use the Internet more tend to socialize less in real life.[x] This is particularly true for those who ‘surf’ a lot. By contrast, people who use the Internet for social purposes have more social ties than non-Internet users.[xi] Nie argued that these individuals were already more sociable before they got online. Obviously, some connections established online do transition to real-world contact and become strong relationships, for example with successful Internet dating.[xii] But the key phrase here is ‘real-world contact’.

More recently, despite ten thousand Facebook friends or a hundred thousand Twitter followers, Dunbar’s research reveals that our ‘real’ social groups have not expanded beyond 150, and within that our core bonds remain at five and fifteen people.[xiii] These findings are based on large-scale surveys of SNS users asked to sort contacts into groups depending on how close they feel to them (how much ‘social capital’ is invested in them).

Why has technology not defeated the Social Brain Hypothesis?

Answer: because we need face-to-face contact to maintain relationships. There is evidence that SNS can stop relationships decaying as quickly as they would without a poke, a like or a Tweet, but ultimately we need to be face to face at least once in a while to stay friends. Without time spent in physical contact, we simply don’t feel as close to those in our network and they drop away to the periphery of our personal solar systems.

What does this mean for me?

Anthropological research is fine, but how does it relate to the individual? This question is particularly important when many of us are spending up to seven hours a day[xiv] using technology, and much of our social connection takes place online.

It means we need to use that tech – at least some of the time – to get out and meet people. Connecting socially in real life is great for our wellbeing[xv]. Social activity apps are a key way to achieve this, though the market is relatively small and still developing.

While our brain size might constrain the number of people we can know well, there’s no limit to the quality of connection we can have with them, so long as we’re face to face.



[i] Dunbar, R. I. M. (2010). How Many Friends Does One Person Need? London: Faber and Faber.

[ii] Dunbar, R. I. M. (2016). Do online social media cut through the constraints that limit the size of offline social networks? Royal Society Open Science, 3: 150292.

[iii] OECD (2007). What is social capital? OECD Insights: Human Capital, pp.102-105. Retrieved August 21, 2016, from: https://www.oecd.org/insights/37966934.pdf

[iv] Dunbar, R. I. M. (2014). The social brain: Psychological underpinnings and implications for the structure of organizations. Current Directions in Psychological Science, 23(2), 109-114.

[v] Fonagy, P., & Luyten, P. (2009). A developmental, mentalization-based approach to the understanding and treatment of borderline personality disorder. Development and Psychopathology, 21(4), 1355-1381.

[vi] Dunbar, R. I. M., Launay, J., & Curry, O. (2016). The complexity of jokes is limited by cognitive constraints on mentalizing. Human Nature, 27, 130-140.

[vii] Dunbar, R. I. M., Arnaboldi, V., Conti, M., & Passarella, A. (2015). The structure of online social networks mirrors those in the offline world. Social Networks, 43, 39-47.

[viii] Wellman, B., Haase, A. Q., Witte, J., & Hampton, K. (2001). Does the Internet increase, decrease or supplement social capital? Social networks, participation and community commitment. American Behavioural Scientist, 45(3), 436-455.

[ix] Bargh, J. A., & McKenna, K. Y. A. (2004). The Internet and social life. Annual Review of Psychology, 55, 573-590.

[x] Nie, N. (2001). Sociability, interpersonal relations, and the Internet: Reconciling conflicting findings. American Behavioural Scientist, 45(3), 420-435.

[xi] Zhao, S. (2006). Do Internet users have more social ties? A call for differentiated analyses of Internet use. Journal of Computer-Mediated Communication, 11, 844-862.

[xii] Bargh & McKenna (2004). Ibid.

[xiii] Dunbar et al. (2015) Ibid.

[xiv] Rideout, V. J., Foher, U. G., & Roberts, D. F. (2010). Generation M2: Media in the Lives of 8- to 18-Year-Olds: A Kaiser Family Foundation Study. Retrieved June 15, 2016 from: https://kaiserfamilyfoundation.files.wordpress.com/2013/01/8010.pdf

[xv] Aked, J., Marks, N., Cordon, C., & Thompson, S. (2008). Five Ways to Wellbeing. New Economics Foundation report. Retrieved June 23, 2016 from: http://b.3cdn.net/nefoundation/8984c5089d5c2285ee_t4m6bhqq5.pdf