
Robin Dunbar pointed out that there are limits to human cognition:
- We can only have a close relationship to about 5 things. 
- We can have a working relationship with about 30 things or people.
- We can only be acquainted with about 150. 

The `Dunbar numbers' are cognitive limits that we have to work around.

http://cfengine.com/markburgess/blog_km.html
