The Dunbar Number

[Editor note: The following notes were made by @harrison during the “The Dunbar Number”, of OpenVillage Festival (19th October 2017). Quotes are not verbatim but summarize what was said. If you feel something is mis-represented, please tell us in a comment or with the “Flag → Something Else” feature and a mod will fix it. – @anu]

(From New York)

Work done in NYC

“Is it relevant to European context?”

(Nabeel question: cultural context, Western centrism of some numbers?) - Something about people being healers?

Goals (extract):

  • Seeing Crisis as an Opportunity: “Vacuum” when US state agency collapsed. Opportunity for us to fill the void.
  • Actionables of this new framework

First, why scales? what does scale mean?

  • 3 people vs 12 people vs 1k people vs millions (a Nation)
  • How number of people impact effectiveness.
  • Dunbar number

What is the Dunbar number?

  • Public discourse “150 friends is the max number of friends” “men should meet twice a week”
  • Scientific definition: “When a group size exceeds this limit, it becomes unstable and begins to fragment. This then places an upper limit on the size of groups which any given species can maintain as cohesive social units through time.”, Robin Dunbar 1992

Human “Fibonacci sequence” (just an analogy)

  • Corporations, Start-up and military build strategies to counter the “Dunbar number” effect like split the engineering teams (corporation), ideation meeting rooms have only 7 seats (start-ups), build small unit (military)
  • We are more versatile in our belonging circles than in the past (tribe as only and sufficient circle)
  • upper and lower limits….

Size of human groups impacts groups dynamics:

  • Working group (5-17): consensus is possible
  • Judas Number (~13): competing people for power (hierarchy) splitting in two groups
  • Non-exclusive Dunbar Number (25-75): not the only group you belong to
  • Dunbar valley (~90): tends to split
  • Exclusive Dunbar Number (~150): greatest number of known exclusive group (tribe), agile institutions and beliefs

Sizes of “circles”

  • support circle 3-5
  • sympathy circle 10-15, e.g. to talk to in some kind of crisis
  • trust circle, about 150 – for easy socialising, and trusting some things but not so much emotional
  • Emotional circle: about 300 – positive affinity for; you know about them, their name, a little bit about them, but not close friends
  • Familiar strangers: about 1500+ – people whose faces you may recognise but you don’t know their names

5 minutes of “Ramp up time” per person means that you can only could have 15 people in your circle


  • Sums of technological solutions (mobile app for doctors, soylent for food) isn’t a answer to health and moreover to “death anxiety”
  • In the US we’re not good to deal with death, death is put away (old people are far away from the center city, we dress differently for funeral)
  • Fist Medicine is actually Community (Us)

I remember @bilal on Day 1 of the festival saying that we have now chosen families, but he finds it difficult to turn to chosen (non-blood) families for care. This relates back to @aquamammal’s circle of support, but it also suggests that the circle of support is not small because of limits to human cognition (as it is in Dunbar), but because of something deeper related to familial ties.

I, too, would be interested in knowing more about this question by Bilal.

There is a lot of insight in @bilal’s observation. Maybe then family isn’t quite the right word for “chosen family” if it doesn’t include that level of commitment. Deep medical care requires commitment and often a lot of financial resources. Coming together to live for an unspecified time, doing work projects together and other deep involvements still generally do not include the level of commitment that generally comes with one’s blood family, at least not in the long arc of one’s life. Even when members of a blood family don’t get along that well, I think there is still in most cases one’s best chance of getting serious care compared to a circle of support or a chosen family if one doesn’t have the resources to afford it for themselves.

Unless that commitment is stated and agreed to, not unlike a marriage…“in sickness and in health.” I have known that kind of commitment with people not in my blood family. But now, years later, although I am still very close to my “tribe” from that time, I do not assume that I would receive that kind of support from them. That said, there are people in the extended group with similar status who have needed more care than they can afford and have received support via GoFundMe type efforts and benefit events. But past something like that, not so much.