Don McClintock

“The 15-layer was already spoken for, of course, in its capacity as the sympathy group. The 5-layer seemed to function as the support clique – the small group of people willing to provide unstinting emotional, physical and financial help and advice. I often refer to this layer as the shoulders-to-cry-on friends. The 15-layer is probably where you draw most of your everyday social companions from – the people you invite round for a quiet dinner or an evening out at the pub or theatre. I am inclined to think of the 50-layer as your party friends: the people you would invite round for a weekend BBQ or a celebratory birthday or anniversary party. The 150-layer is what you might call the wedding/bar mitzvah/funeral group – the people that would turn up to your once-in-a-lifetime events. It also probably contains most of the children of your closer friends. Otherwise, our women’s network data suggest that this layer is mainly populated by members of your extended family – people whose friendship does not need much regular reinforcement because it is held in place by the ties of kinship.”
― Robin I.M. Dunbar, Friends: Understanding the Power of our Most Important Relationships