The Tipping Point: How Little Things Can Make a Big Difference

by Malcolm Gladwell

Dunbar’s argument is that brains evolve, they get bigger, in order to handle the complexities of larger social groups. If you belong to a group of five people, Dunbar points out, you have to keep track of ten separate relationships: your relationships with the four others in your circle and the six other two-way relationships between the others. That’s what it means to know everyone in the circle. You have to understand the personal dynamics of the group, juggle different personalities, keep people happy, manage the demands on your own time and attention, and so on. If you belong to a group of twenty people, however, there are now 190 two-way relationships to keep track of: 19 involving yourself and 171 involving the rest of the group. That’s a fivefold increase in the size of the group, but a twentyfold increase in the amount of information processing needed to “know” the other members of the group. Even a relatively small increase in the size of a group, in other words, creates a significant additional social and intellectual burden.