I have often observed chaotic meetings or been frustrated by group discussions that seem to lose the plot. I had never really thought about why this happens other than to complain under my breath about a weak chairperson or facilitator or to mutter “stick to the point” now and then. Now, at least, I have found a partial explanation: Christopher Allen has an interesting article, “The Dunbar Number as a Limit to Group Sizes” where he provides some evidence and relates to more fundamental anthopological research.