In his 2010 book “How Many Friends Does One Person Need?” Robin Dunbar, Director of Cognitive and Evolutionary Anthropology at Oxford University concludes that the cognitive power of the brain limits the size of social networks that any one species can develop. Drawing upon his study of the brain sizes and social networks of primates, Dr Dunbar suggests that the size of the human brain permits the formation of stable networks of 150 people (see page 4).

His argument is that in a context where meaningful relationships require a certain investment of time as well as emotional and psychological capital; there are sociological and anthropological limits to the number of people who we can know personally, trust and feel emotional affinity for. In practice the size of a broad range of social groupings have been shown to conform to the “Dunbar Number”, from Neolithic villages and military units from Roman times to the present (Harvard Magazine 2010) to the average number of friends people have on Facebook (New York Times 2010) and even the average number of Christmas cards households send out every year (Bloomberg Businessweek Technology 2013).

This research has fuelled a trend towards smaller online social networks – Path a mobile social networking application established in 2010 explicitly limits the number of friends users can add to 150 (based on the assumption that people generally have 5 best friends, 15 good friends and 50 close friends and family). As of September 2012 the Path network has expanded to over 3 million users (CNET 2012). In November 2010, South Korean firm VCNC launched a mobile social networking application “Between” which offers a private online space for couples to share photographs, memories and chat in real time. In January 2013 VCNC secured $230 million to grow its business internationally after reaching 2.35 million downloads (The Next Web 2013). Other mobile social networking applications such as Storytree and Familyleaf have been established to provide private online networks for family members. The question remains, will this trend contribute to denser more meaningful online social exchanges, or divide the web into introverted and fragmented social enclaves?