From Wiki Gonzalez
The denizens of Baseball Primer were not originally called "Primates." It appears that Jim Furtado first presented the term on August 30, 2002 in the "Fantasy Baseball 2002 - Coorespondents" thread, and it stuck, inspiring later creations like the Primer Chimp.
Well before Jim Furtado published the term "Primates," Rich Rifkin claims to have coined the term. It came about in a series of group emails that were shared by about 10 early members, including Furtado, Sean Forman, Voros McCracken, et al. In those early days, they were trying to create more original content on the site. And in one of Rich's emails to the group, he referred to himself and the others as "Primates."
For more information about small-p primates, you can start with this.
There is a list of known Primates.