Look at the picture above. There are about 150 or so people in a room. But notice how they are interacting. There are many small groups, and a few loners. It’s not 150 people in a room interacting, it’s a series of groups of people who happen to be in the same room. (The room, by the way, was the antechamber at last year’s MapCamp. It’s a blurry enough image that most people’s identities are safe…)

There’s only one way that it would be a group of 150 people interacting, and that would be to dramatically change the nature of the room. Which is what happened later as a few hundred people sat in neat, orderly rows and watched individual speakers. Interactions became transactions.

This is a theme I’ve been plundering recently. And I’m coming to the conclusion that interactions between people can’t scale. You can turn them into transactions, but those are not the same thing at all. And this is important when it comes to thinking about how teams work.

Here’s my reasoning:

7 +/- 2

Apparently, George Miller’s The Magical Number 7 Plus or Minus 2 is one of the most cited papers in psychology. The paper from 1956 argues that the most number of things that the average human brain can hold in working memory is 7, plus or minus 2. (Don’t you love it when an academic paper says exactly what it’s going to do in its title?)

When it comes to working groups, just being able to keep the people you are working with names in your head can be a challenge. Let alone what they are up to. Teams of seven or fewer from my experience can kind of just get along without too much structure or process. I conclude that Miller’s Magic Number is partly at play.


British Anthropologist Robin Dunbar looked at the social activities of various primates and concluded that humans have the cognitive ability to maintain around 148 people connections at any given time.

For a long while I’ve argued that social networks give us the ability to “manage” the rest and then switch people in and out of the 148 at a greater pace than we would have been able to do in the past, but nonetheless the Dunbar number is unchanging.

Keep in mind that figure is for your whole world, not just work or not work. So when I hear of people who have line management responsibility of 20 or 30 people (particularly in self-proclaimed “flat” tech organisations) I fear deeply for both the manager and the managed.

As many people as you can address in a single meeting

This is a quote from Aristotle that I picked up in Tom Standage’s book The Writing on the Wall. Aristotle proposed that the ideal city would consist of no more people than can be addressd in a single meeting.

I reckon that’s probably up to maybe 1,500 people in a good Greek amphitheater with no amplification. Organisations go really weird when they get bigger than around 1,500 people. Amplification won’t help you.

The quest continues…

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