The Hills Are Alive with the Sound of Interaction Design
I will cite two bits of circumstantial evidence that humans are physically and socially optimised for small groups.
I mention the first, from Dunbar’s Co-Evolution of Neocortex Size, Group Size and Language in Humans, primarily because I love the word “psycho-physical.”
There is, I quote, “a psycho-physical limit on the size of conversation groups.”
For normal human ears, against a normal ambient noise background, for the normal volume of human speech, and the physics of how noise attenuates through air, the optimum distance for two people to hold a conversation (well, the upper limit) is, nose to nose, 1.7m.
At that distance, standing round in a circle, shoulder to shoulder at a distance of 0.5m, you can fit in five people. Five.
And you can observe this rough upper limit on conversation groups when you go out with a group of friends. See what happens when a sixth person joins the group, and a seventh. The group starts oscillating between single and multiple conversation modes. It’s awkward. You have fractured conversations, or maybe it feels like one person is dominating the group. Keep dropping in more people, an eighth, a ninth. When you get to 12 people, or fewer in a louder place, the group breaks into multiple conversations much more comfortably.
My second piece of circumstantial evidence is an old Anglo-Saxon, and then Norman law, dating from about 1000 years ago. It is frankpledge:
A person, a free person, must be held in a frankpledge. The pledge is of ten people, who are mutually liable to bring a member to justice if they break the law.
So I would be placed in a group of 10 people. If someone in my pledge stole a sheep or didn’t pay their taxes, it would be the responsibility of the other 9 of us to bring them to justice. If we didn’t, we’d all suffer.
This is the roots behind 12 people being in a jury, by the way.
What’s great about the frankpledge is that it’s the right number of people to establish trust and exert social pressure without it being oppressive. You don’t need laws for that small number. You just keep an eye on each other, and check each other before you transgress too far.
In short: With small groups, you don’t need technical fixes to social friction. In fact, sociality solves its problems on its own, because the people are in contact so much. That means we can have technical systems that are way more ambitious and risky, because we don’t need to be so careful about weird social failure modes.