Dunbarian reflections

Dunbar's number is an hypothesized limit to the number of social relationships one can process.  Dunbar figured our tiny brains could only handle so much social interaction (about 150, he thought), but I wonder if this isn't somehow an equilibrium problem between the individual and the network.  Looking at my own engagements:

• I've been on Linkedin since 2004, and have about 600 connections.  I don't personally know some of these people, due to accepting links for other information reasons, or as a favor to people I do know.  I'd estimate the "real" network at about 300.
• I've been on Twitter for maybe six months, and follow about 300 people.  The number's been stable for a while - I follow and un-follow, but that seems to around the limit.
• I snuck onto my wife's Facebook account, and there are, again, about 300 relationships.

So all of these network relationships are falling into this one order of magnitude.  There seems to be some asymptotic thing working here...it's not our ability to form relationships because these are distinct networks with very little overlap.  It seems more to do with getting what we want from a particular network and reaching satiation once a certain number of contacts is established.

Which helps explain why new ones keep springing up - each new platform is a chance to start fresh, with new people (?) and new priorities.  If you use Facebook to argue religion with your relatives maybe you can use Twitter to set up concerts with your college friends.

But I do think Dunbar is onto something.