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Les McKeown's Predictable Success Blog

  • February 20, 2022
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What's Your Magic (Dunbar) Number? 

Listen to Les McKeown read this blog post:

In the 1990s a British anthropologist, Robin Dunbar, postulated something that many growth leaders had viscerally intuited: once a group grows larger than around 150 people, social constructs dilute to the point where dysfunctions begin to occur. 

Several organizations have used this so-called ‘Dunbar Number‘ as a limit for the size of individual operating units. Gore-Tex, for example, constructed company buildings with room for only 150 people

The Dunbar Number is something I see fast-growing organizations bumping up against all the time – in fact, it’s one of the major contributing factors to pushing them into the stressful growth stage I call Whitewater.

"Once a group grows larger than around 150 people, social constructs dilute to the point where dysfunctions begin to occur". - Les McKeown, Founder and CEO, Predictable Success 

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Broaching the Dunbar Number amplifies silo-ization, contributes to the breakdown of cross-functionality and dilutes alignment – three of the clearest symptoms that you’ve left Fun and have indeed fallen into Whitewater.

Here’s the kicker:

Unlike in the field of anthropology (Professor Dunbar’s area of study), an organization’s Dunbar Number isn’t so easily narrowed to 150.

A virtual company’s Dunbar Number, for example, will be much lower (it can be as low as 20 people) than say, a manufacturing company (where 150 is typically pretty accurate) - and a highly Synergistic business will have a higher Dunbar number than say, an Operator-dominant company.

So how can you tell you’re reaching your Dunbar number, and what should you do about it when you do? Here’s my personal Predictable Success finger-in-the-air test: 

The first time you see someone walking down the corridor and you can’t remember their name, you’ve entered the Dunbar Zone…and the first time you see someone and can’t recall even hiring them – you’ve hit your number.

And if so, what should you do? Obviously not everyone can simply go find another office building, like Gore-Tex, so here are some other tools you can use: 

1. Amp up the communication.

Start water cooler sessions, increase the frequency of all-company meetings, start an internal company blog – anything to force non-siloed interactions. 

2. Carve out a ‘commons‘.

Create a place or places where your people can mix in a relaxed, non-work environment, both physical and virtual. (The classic ping-pong table is a great start, but in this era of hybrid work environments is not nearly enough.) 

3. Start walking around.

Don’t just meet with your peers and direct reports – get out into the corridors, offices, cubicle farms, factory floors, Slack channels and Zoom Rooms and talk. Talk. Talk. Engage with your people as people, be open and accessible.

One thing is guaranteed: unless you want a dysfunctional, siloed, increasingly ineffective business, once you’re in the Dunbar Zone, inaction is not an option.

What about you? What's your Magic Number? 

Let Me Know In The Comments Below!


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