Nellie (our Black Lab that passed in Feb. 2011) was an outdoor dog. Well actually toward the end an indoor and outdoor dog. When I say outdoor, Nellie (and now Fitch and Bella) have a "doggie door" that allows free access into the garage - which is actually their "dog house". Nellie would "follow" us around the house by lying near our sliding doors or window in the rooms where we would sit (she would be outdoors and we would be indoors). It is just instinct to want to be near someone - even if there is no interaction and in the case of Nellie even if you couldn't be directly in the same room.
Today, I am sitting out on our front courtyard enjoying the bubbling fountain, the morning sun rising in my eyes and the sound of birds just after the walk with the puppies. And there they lay - Bella on the chair next to mine and Fitch at my feet. They have the whole yard to pick from to relax - yet they prefer the companionship of being near me. No interaction - just sitting together.
I noticed this with Susan or the kids. There are many evenings that there is very little interaction, yet the comfort of sitting together - each person doing their own personal thing (watching TV, reading, blogging etc.) - is just a part of our instinct also.
I think that is why the social networking sites like Facebook, and Linkedin have some appeal. It is a virtual world of sitting together.
Postscript: Just to prove the point. Susan just joined me. She took Bella's seat and reads the paper silently. Just a hi and then we sit together.