Christopher Allen
In many discussions on social networks the number 150 comes up as a ‘natural’ limit to how much social interaction a person on average can handle.
Intuitively I always felt uneasy with this number, and have on several occasions suggested that this could only be a limit in a specific context on a specific point in time, as this fits much better with personal experience and anecdotal evidence. (See references further down this post)
Christopher Allan, author of Life with Alacrity now comes with a thorough analysis and origins of the ‘magical’ 150.
The anthropologist Dunbar predicted the 150 as group size, based on brain-size, as the number of relations we can keep up by grooming. Language disrupted that barrier, being a much cheaper way (in brain usage) for ‘social grooming’. So taking 150 as an optimum or limit would be false. By coincidence this concept of language as a cheap solution to grooming came up last week during a dinner preparing for BlogWalk. I think it was Janine Swaak who mentioned it. Check out her blog on ‘Knowledge Animals’.
Chris then goes on the apply Dunbar to on-line communities. It wouldn’t do to try and summarize it here. Go read Chris’s posting, as he also links to several other postings e.g. by Ross Mayfield that hold relevance to this.
Also read these comments by Martin Dugage (Mopsos) and Lee Bryant (Headshift moments).

Primates without language, at Emmen zoo, spring 2003

Previous comments I made about the 150 threshold:
Lurking and Social Networks
Taking it one step further, maybe the ‘magic numbers’ we see in networks of humans relate these meshing concepts to our mental capacity to juggle social data.

  • 12 being the average capacity to track nodes in a totally meshed network
  • 50 being the average capacity to track nodes in an optimally meshed network
  • 150 being the average capacity to track nodes in a sub-optimally meshed network.
  • above 150 being the sparsely meshed social network where anonymity and getting lost becomes possible.
    Networking Stagnation Fatigue or Growing Pains? II:
    I can come up with a little over 170 names of people I am in regular contact with. So the limit seems about correct at first glance. Thing is, I don’t feel my network is full. […] If I’d adhere to the 150, my guess would be that 150 is more likely to be a mental limit for any one of the contexts [ I move around in].
    The Tipping Point (book review):
    For an idea to become epidemic you will have to keep this threshold of 150 in mind. It will not do to convince a whole stadium with 15.000 of something; the mass will go home not remembering you. But reach a 100 of those groups of 150 and you�re rocking. Now the book seems to imply that each of us functions in a context of about 150 people.
    That does not sound right to my ears, especially if I look at the examples given. For instance a company is mentioned that is organised in independent business units of 150 people. But each of those 150 employees will have a life outside of the company as well, so even if those workers indeed know 150 people, they won�t be all colleagues. Is Malcolm Gladwell implying we can only keep track of a group of 150 people at any one time, but can easily switch groups, because that is what seems to fit my own experience more?