This is because our human brain can only handle around 150 meaningful relationships – that is, you know how the 150 people fit into your life, and they know how they fit into yours.
Apparently, this is a “direct function of the relative neocortex size” meaning the brain can only process a certain amount of information on stable friendships. This includes all close friends, family, colleagues and acquaintances, as well as past colleagues, school friends and people you might want to reacquaint with should you meet them again.
For some, his theory has become a “Law”. 150, that’s it.
We see the 150 number cropping up throughout history. In his original 1992 paper, Dunbar showed how early non-human primates grouped into clusters of 148. Later, neolithic farming villages tended to contain no more than 150 people (the ‘DoomsDay’ Book showed this too), and the basic size of Roman armies topped off at 150. Property managements max out at 150 per manager don’t they? Realestate.com.au account managers look after no more than 150 accounts. [So you see, it must be law!]
Dunbar further showed that for a group to have cohesion, it should have no more than 150 members. Companies or groups that grow beyond that size need to be physically broken up into smaller units in order to retain cohesion with that organisation.
Think about your own lives and its implications.
How many people do you have a meaningful stable relationship with at the moment (in real estate, technology and beyond)? Even for those with hundreds and thousands of ‘Facebook friends’ and ‘Twitter followers’, how many do you think they/we actively engage with? What does this mean for client relationship management (CRM) activities and software? For those real estate professionals with thousands of contacts that receive their regular blasted enewsletters, ebrochures and the like, what sort of meaningful interaction is going on?
Lots of business can be done by being the local real estate expert forged through solid, meaningful and trusted long term relationships. Maybe in our rush for technology, we over complicate matters, and rush to seek short cuts to contact loads of people, shotgun style? Should we just be happy with our 150 ‘meaningful relationships’ and make the most out of these contacts?
Disclosure: our company has 150 clients. Now I know why…
For More:
Dunbar, Robin. (1992) Neocortex size as a constraint on group size in primates, Journal of Human Evolution 22: 469-493.
Dunbar, Robin (1998). Grooming, Gossip, and the Evolution of Language. Harvard University Press
Gladwell, Malcolm (2000) ‘The Tipping Point’ . (Dunbar’s Law forms a central part of Gladwell’s argument and probably first made him famous)