### Every day during September we will post up an idea for you to vote on. The most popular ideas will become the things that the inaugural Organizing Committee of the Critical Physiotherapy Network focuses on in 2015. So please make sure you **cast your vote** at the bottom of each post.

“*… there is a cognitive limit to the number of individuals with whom any one person can maintain stable relationships, that this limit is a direct function of relative neocortex size, and that this in turn limits group size … the limit imposed by neocortical processing capacity is simply on the number of individuals with whom a stable inter-personal relationship can be maintained.*”

Now I know this isn’t the kind of post you were expecting, but it belies a serious point. Our network has grown very quickly, and we’re soon going to reach a size where it’s going to be increasingly difficult to keep everyone engaged. Dunbar’s number is a famous calculation based on ‘the group size of a variety of different primates’. Dunbar correlated ‘group sizes to the brain sizes of the primates to produce a mathematical formula for how the two correspond. Using his formula, which is based on 36 primates, he predicts that 147.8 is the “mean group size” for humans, which matches census data on various village and tribe sizes in many cultures’ (source).

I confess I have absolutely no idea what this means. And how can you have .8 of a person in a group anyway? This notwithstanding, we should think about limiting the size of the group to a specific number of keen, active participants to keep the group alive. Networks like ours – particularly the ones that are not physically close to each other – can tend to drift into apathy over time, particularly if they’re not being driven by a charismatic, handsome and charming leader. So putting a set limit on the group and making sure only people who are active in the group stay in the group might make sense if we want the group to thrive.

**Post update:** please note that voting closed on 7 October 2014 (results are available here), but please feel free to post your comments in the space below.

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