Proponents assert that numbers larger than this generally require more restrictive rules, laws, and enforced norms to maintain a stable, cohesive group. Dunbar theorized that “this limit is a direct function of relative neocortex size, and that this in turn limits group size the limit imposed by cortical processing capacity is simply on the number of individuals with whom a stable inter-personal relationship can be maintained”.
On the periphery, the number also includes past colleagues, such as high school friends, with whom a person would want to reacquaint himself or herself if they met again. The number of social group members a primate can track appears to be limited by the volume of the neocortex.
This suggests that there is a species-specific index of the social group size, computable from the species' mean cortical volume. In 1992, Dunbar used the correlation observed for non-human primates to predict a social group size for humans.
Using a regression equation on data for 38 primate genera, Dunbar predicted a human “mean group size” of 148 (casually rounded to 150), a result he considered exploratory due to the large error measure (a 95% confidence interval of 100 to 230). Dunbar then compared this prediction with observable group sizes for humans.
Dunbar's surveys of village and tribe sizes also appeared to approximate this predicted value, including 150 as the estimated size of a Neolithic farming village; 150 as the splitting point of Hübnerite settlements; 200 as the upper bound on the number of academics in a discipline's sub-specialisation; 150 as the basic unit size of professional armies in Roman antiquity and in modern times since the 16th century; and notions of appropriate company size. Dunbar has argued that 150 would be the mean group size only for communities with a very high incentive to remain together.
Correspondingly, only groups under intense survival pressure, such as subsistence villages, nomadic tribes, and historical military groupings, have, on average, achieved the 150-member mark. Moreover, Dunbar noted that such groups are almost always physically close: “ we might expect the upper limit on group size to depend on the degree of social dispersal.
Dunbar, in Grooming, Gossip, and the Evolution of Language, proposes furthermore that language may have arisen as a “cheap” means of social grooming, allowing early humans to maintain social cohesion efficiently. Without language, Dunbar speculates, humans would have to expend nearly half their time on social grooming, which would have made productive, cooperative effort nearly impossible.
Language may have allowed societies to remain cohesive, while reducing the need for physical and social intimacy. This result is confirmed by the mathematical formulation of the social brain hypothesis, that showed that it is unlikely that increased brain size would have led to large groups without the kind of complex communication that only language allows.
Dunbar's number has become of interest in anthropology, evolutionary psychology, statistics, and business management. For example, developers of social software are interested in it, as they need to know the size of social networks their software needs to take into account; and in the modern military, operational psychologists seek such data to support or refute policies related to maintaining or improving unit cohesion and morale.
A recent study has suggested that Dunbar's number is applicable to online social networks and communication networks (mobile phone). Participants of the European career-oriented online social network XING who have about 157 contacts reported the highest level of job offer success, which also supports Dunbar’s number of about 150.
Anthropologist H. Russell Bernard, Peter Kill worth and associates have done a variety of field studies in the United States that came up with an estimated mean number of ties, 290, which is roughly double Dunbar's estimate. The Bernard–Kill worth median of 231 is lower, due to an upward skew in the distribution, but still appreciably larger than Dunbar's estimate.
The Bernard–Kill worth estimate of the maximum likelihood of the size of a person's social network is based on a number of field studies using different methods in various populations. Philip Lieberman argues that since band societies of approximately 30–50 people are bounded by nutritional limitations to what group sizes can be fed without at least rudimentary agriculture, big human brains consuming more nutrients than ape brains, group sizes of approximately 150 cannot have been selected for in paleolithic humans.
Brains much smaller than human or even mammalian brains are also known to be able to support social relationships, including social insects with hierarchies where each individual “knows” its place (such as the paper wasp with its societies of approximately 80 individuals ) and computer -simulated virtual autonomous agents with simple reaction programming emulating what is referred to in climatology as “ape politics”. Comparisons of primate species show that what appears to be a link between group size and brain size, and also what species do not fit such a correlation, is explainable by diet.
Many primates that eat specialized diets that rely on scarce food have evolved small brains to conserve nutrients and are limited to living in small groups or even alone, and they lower average brain size for solitary or small group primates. Small-brained species of primate that are living in large groups are successfully predicted by diet theory to be the species that eat food that is abundant but not very nutritious.
Along with the existence of complex deception in small-brained primates in large groups with the opportunity (both abundant food eaters in their natural environments and originally solitary species that adopted social lifestyles under artificial food abundances), this is cited as evidence against the model of social groups selecting for large brains and/or intelligence. Malcolm Gladwell discusses the Dunbar number in his popular 2000 book The Tipping Point.
Gladwell describes the company W. L. Gore and Associates, now known for the Gore-Tex brand. By trial and error, the leadership in the company discovered that if more than 150 employees were working together in one building, different social problems could occur.
The number has been used in the study of virtual communities, especially MMORPGs, such as Ultimo Online, and social networking websites, such as Facebook (Dunbar himself did a study on Facebook in 2010) and MySpace. The Swedish tax authority planned to reorganize its functions in 2007 with a maximum 150 employees per office, referring to Dunbar's research.
In 2007, Cracked.com editor David Wong wrote a humor piece titled “What is the Monkey sphere?” In the 2012 novel This Book Is Full of Spiders, also by David Wong, the character Marconi explains to David the impact Dunbar's number has on human society.
In Marconi's explanation, the limit Dunbar's number imposes on the individual explains phenomena such as racism and xenophobia, as well as apathy towards the suffering of peoples outside an individual's community. In a piece for the Financial Times (10 Aug 2018), titled 'Why drink is the secret to humanity’s success' Dunbar mentioned two more numbers: an inner core of about 5 people to whom we devote about 40 percent of our available social time and 10 more people to whom we devote another 20 percent.
Dunbar has now decided to shift focus to see whether Facebook has changed the number. Grooming, gossip, and the evolution of language (1st Harvard University Press paperback ed.).
“Unraveling the size distribution of social groups with information theory on complex networks”. ^ Dunbar, Robin (2004), “Gossip in Evolutionary Perspective” (PDF), Review of General Psychology, 8 (2): 100–110, Cutesier 10.1.1.530.9865, DOI : 10.1037/1089-26126.96.36.199, S2CID 51785001, retrieved 24 January 2013 Dávid-Barrett, T.; Dunbar, R. I. M. (22 August 2013).
“Virtual Resistance: Internet-mediated Networks (Dot causes) and Collective Action Against Neoliberalism” (PDF). ^ Gonçalves, Bruno; Perry, Nicola; Perpignan, Alessandro (3 August 2011).
“Modeling Users' Activity on Twitter Networks: Validation of Dunbar's Number”. ^ Giovanna Murillo; Esteban Moro; Ruben Lara; Rocco Martínez-López; John Bedchamber; Sam G.B.
“Time as a limited resource: Communication strategy in mobile phone networks”. “Getting a job via career-oriented social networking markets: The weakness of too many ties”.
Pirates, Terrorists, and Warlords: The History, Influence, and Future of Armed Groups Around the World. ^ McCarty, C.; Kill worth, P. D.; Bernard, H. R.; Johnson, E.; Shelley, G. (2000).
Paper presented to the University of Southampton, 28 September 2006. http://nersp.osg.ufl.edu/~ufruss/ ^ Lieberman, Philip (2013). The Unpredictable Species: What Makes Humans Unique.
There was a time when Groups a user was a member of would appear on their own personal page. Now, however, those types of open forums are known as Pages, created by companies, celebrities, and brands to engage with their audience and post interesting content.
So, if someone were to visit the NFL on CBS Facebook Page, they could see anyone who was commenting on a photo or discussing an article. This could cause some privacy concerns, especially if you do not have a solid understanding of how to protect your personal profile.
A Group can be more private than a Page since the creator has the option to make it closed. An example of a Group might be team members who are working on a project together and want to communicate with one another more efficiently.
By creating a Group, the team is given a private forum to share ideas on the project and post updates, just like with a Page. These Groups could be used if you are planning an event that you do not want somebody to know about, or if you just want a secure platform to talk with friends.
Also, while a Page can accumulate as many likes as possible, a group must be kept at 250 members or lower. Once inside the Group, Facebook works only slightly different from your profile.
A Group does not use the timeline but rather displays posts in direct chronological order, similar to the pre-timeline manner. Another difference between joining a Group and liking a Page is the number of notifications that you receive.
This is just one of the many ways Facebook Pages allow you to monitor the audience and how well your product or message is being received. These analytics are not offered, or needed, in Groups because they're meant to communicate with a small, select number of people rather than a wide-scale audience.