Do you have more than 150 friends?

Do you know more than 150 people? You probably don't. And do you have more than 150 friends on Facebook and followers on Twitter? You probably do. But are they really your friend? Do you really know all 150 of them? I don't think so.

A long time ago I ran into Robert Dunbar's research on social networks. I wrote several posts about Dunbar's number and have been collecting interesting links as well. Just recently Dunbar was interviewed  by Technology Review about his number and social networks.

What is Dunbar's number about? His research basically showed...

...that humans have the cognitive capacity to maintain about 150 stable social relationships. 

The first time I read this I thought: What?! But it's is now my experience this is true. Even for social media friends and followers. I follow way more that 150 people, but I know and truly engage with 150-300 of them.

Of course Technology Review was also wondering if Dunbar himself still thinks his number still hold in the social era. Has the number changed due to social media. This is his response:

Apparently not at all. It is important to remember that the 150 is just one layer in a series of layers of acquaintanceship within which we sit. Beyond the 150 are at least two further layers (one at 500 and one at 1,500), which correspond to acquaintances (people we have a nodding acquaintance with) and faces we recognize.
All that seems to be happening when people add more than 150 friends on Facebook is that they simply dip into these normal higher layers. If you like, Facebook has muddied the waters by calling them all friends, but really they are not.

To me this also has implications for organizations as well. If Dunbar's number is correct companies larger than 150 employees have a problem. Employees simply can't know each other anymore. So, employees can't know what (all) other employees know. Shouldn't this have implications for the size of organizations? And isn't this also a good reason to use internal social tools, as they can make visible what other employees know and support the stream of information in the organization for effectively and quickly?

I don't know if it had to do with Dunbar's numbers, but there is a Dutch entrepreneur, Eckart Wintzen, that split his companies every time they grew larger than 50 employees. And Dave Gray's work on podular organization fits perfectly with this as well.

I'm curious what you think of Dunbar's number. Does it relate to your practice? And what are your thoughts on Dunbar's number and organizational size?

UPDATE (2 hours later): Talk about serendipity! Just hours after I published this post, ReadWriteWeb published a post about the same topic: 'Facebook Friends: How Many are Too Many?'.