Communities and the magic 150

I went to school back in the days when schools were small. My junior school had about 100 pupils and my secondary school about 250. I knew everyone in the first school and many in the secondary school -- I recognised everyone and knew most by reputation or family. The school seemed big after my first school but I got used to it. I didn't realise it at the time, but I was subject to the Law of 150.

Man is historically a tribal animal. Evolution has taught that living in cohesive groups works better than trying to survive alone. Cities are relatively recent inventions -- village-sized communities are the living groups that we've been used, and it's interesting how, even today, neighbourhoods are often a more important component of our identity.

The magic number for 'large' groups turns out to be 150 people. Larger than this and we find it increasingly difficult to know everyone. Consequently, there is less interpersonal loyalty and less overall cohesiveness. And it all goes back to the size of the villages in which we lived for so long. When people did not travel much, they would be lucky even to meet more than a few hundred in their entire lifetime.

The implications for modern business is to avoid large units, fragmenting primary groups into units around this size. An example from my history is in Hewlett Packard, where divisions would spin off.larger developments into new divisions. It is no surprise that, from the days of the monolithic behemoth, HP was a nimble player who rose to the top of the computer industry..

Your comments

Interesting numbers.

The thing that amazes me are the huge bird colonies. How these creatures distinguish between thousands of their fellow creatures who appear visually identical.

Birds of a feather may well flock together, as long as they don't return to the wrong nest! I once read that domestic chickens could recognize up to 30 of their fellows. Must be a conservative estimate.

I also heard (wish I could remember where) that human beings will meet up to 10,000 people in a lifetime, yet consistently with only consider less than a dozen close friends.

Then there is the "Six Degrees of Separation" effect. That is, how many people you know by "networking" -less than six nodes.

Having grown up in in a region with a small population, then move to a large city one is often asked: ".....oh, you are from -----, do you know so and so?....". I would reply, don't be ridiculous, there are hundreds of thousands of people there! Then it would turn out that I actually knew, or knew of, the person.

I would never admit it though!

Petty or not, it is always a small world.

-- peter

Dave replies:

They all look the same to us, but I guess to a seagull, that lass over there is strangely attractive...

We do this with out-groups and stereotypes. Long/short-haired kids these days (let along other ethnic groups) do look rather similar. The thing to remember is that we also look similar to them.

I believe I'm right in saying that 150 is also the number at which most growing churches get stuck, unless they create other methods (typically small groups) to preserve feelings of community. Ironically, the larger the church the more lonely a visitor feels. Small groups provide the route into deeper relationships.

-- Roger

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