# Facebook, Dunbar’s Number and current killer apps

By Murray Bourne, 20 Dec 2007

British anthropologist Robin Dunbar conducted research in the 1990s on the optimum social network size for primates. It turns out that there is a correlation with neocortex volume - the bigger the brain, the bigger the possible social network. This stands to reason, since being able to recognise faces and to know the pecking order for everyone in the group takes brain power.

For humans, Dunbar's Number is approximately 150. This means that to be able to know each member in a community and to know where they fit in that community, we are limited to about 150 as the community size. Throughout history, 150 has appeared as a fairly common social grouping size in cases like villages and army units where there has been a strong reason (like war) to stay in close physical proximity and work together.

Read more in The Dunbar Number as a Limit to Group Sizes (which has some interesting info on the size of online mutliplayer game groups) and Wikipedia's article, Dunbar's Number.

Now to Facebook (and MySpace, Flickr, countless blogs, wikis, Del.icio.us, StumbleUpon, etc). How many friends do you have on Facebook? If you have 300 friends, do you really know them all and can you claim that you are all 'close'? Does it matter? Why has social networking (and collaborating and commenting and tagging) taken off in such a big way? And how big is a 'meaningful community' in each of these sites?

More importantly, marketers have recognised the power of social networking and have realised it will be more effective than traditional advertising. If one person in the community has bought a product and liked it, it is more likely that others in that community will buy that product on one recommendation. Word of mouth advertising has always been powerful, but with the Web, there is greater potential for the spread of 'believable' recommendations.

Also, viral marketing is an extraordinary phenomenon. One of my favourites: Will it Blend. The nature of advertising budgets is changing rapidly.

For another interesting article on Dunbar's Number and marketing, see Relationships are the Killer App and Marketing Rules.

And what's it all got to do with education? For years I have been listening to lecturers moaning that online learning can never be as good as face to face teaching because students would rather interact with humans than with computers. But the explosion of online social networking indicates that this is a flawed argument. People can - and do - form strong communities online. When it comes to online learning, the 'community' issue is a vital one. If there is no sense of community it usually means the student has no desire to come back.

There are lessons in all of this...

See the 1 Comment below.

### One Comment on “Facebook, Dunbar’s Number and current killer apps”

1. Itay Hazan says:

Dunbar illuminated on the human brain capacity to form meaningful relationships, also limited by geographics and the psycho-evolutionary tendency to create meaningful communities.
Yet in the Information age, where online dating, numerous business connections and random-serendipitous connections are found daily these correlations are not a limiting factor when creating social metadata.
That is to say, the facebook average friend list is usually larger than Dunbar's, and if not it will soon.

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