In 1856, the Norwegian ethnologist Eilert Sundt described the rural social structures of Norwegian peasants (and their farms) called “bedelags” (Google translates this as “prayer teams”). These “bedelags” became visible at certain social events (like funerals) when people from different farms came together.
Sundt noted that, if visualised, the rural social network would look like a set of “nonconcentric circles, each with one farm at the center and a number of others at the periphery” where “each circle always intersects several others” (both paragraphs and direct quotes cited from Caulkins 1981: 28-29).
According to Caulkins (1981: 30), these observation were a largely unnoticed predecessor of what became social network analysis in the 20th century.
Now, 155 years later, Google introduces an online social network called Google+ that has “circles” as one of the central innovations. I suppose the copyright belongs to Norwegian farmers and a 19th century ethnologist.
Note: For my academic research, I study political networks. I’ve discovered the text by Caulkins (1981) this January.