Dunbar number & Web 2.0

Few weeks ago, Jon (webpage, blog) gave a very interesting presentation about his new project “Social Nets“. That talk put me in a rare condition – it made me really think (quite an achievement, given my persistent vegetative state you might say) :) Anyhow, after the talk, I was wondering whether the Dunbar number still holds today

  • ” Several years ago Robin Dunbar concluded that the cognitive power of the brain limits the size of the social network that an individual of any given species can develop. Extrapolating from the brain sizes and social networks of apes, Dr Dunbar suggested that the size of the human brain allows stable networks of about 148. Rounded to 150, this has become famous as “the Dunbar number”.

Is this still true? Web 2.0 tools may have well increased the size of our social circles, right? Probably not! In “Primate on Facebook“, The Economist comments on the analysis done by Cameron Marlow (the “in-house sociologist” at Facebook) and interestingly concludes that:

  • “What mainly goes up, therefore, is not the core network but the number of casual contacts that people track more passively. This corroborates Dr Marsden’s ideas about core networks, since even those Facebook users with the most friends communicate only with a relatively small number of them.”

From  the SOCNET list:


(Charles Ehin says) I’ve used the “Dunbar Number” since its publication in developing many of my social dynamics models. I believe the Dumber Number can only be realistically applied to groups that at least occasionally meet face-to-face. That is because face-to-face interactions also bring into play hormonal and neurological changes in people involved which are minimized/excludes in virtual relationships.  The new field of “social neuroscience” in the past 5 years has made some groundbreaking discoveries (and continues to do so) about our neurological/chemical activities that take place in our face-to-face interactions as summarized below:

  • Hormones: oxytocin and vasopressin promote trust and bonding.
  • Neurotransmitters: dopamine (enhances attention) and serotonin (reduces fear and worry).
  • Mirror cells: reproduces other person’s actions/emotions in our brains.
  • Spindle cells: instantly choose best response among many.
  • Oscillator cells: regulate how and when bodies move together. cortisol production: keeping secrets (even advising someone to keep a secret) increases cortisol production (free salivary), while communicating affection can lower cortisol production…

One Response to “Dunbar number & Web 2.0”

  1. Neal Lathia says:

    There is an interesting comparison (and use of the Dunbar number) in an analysis of facebook user’s activity: http://tinyurl.com/d7cgok